Today’s Technician: Automotive Engine Repair & Rebuilding, Classroom Manual and Shop Manual, Spiral bound Version [6 ed.] 2017930371, 9781305958111, 9781305958135

Table of contents :
Classroom Manual
Cover
Contents
Preface
Chapter 1: Automotive Engines
Terms to Know
Introduction
Basic Engine Operation
Cooling System
Lubrication System
Engine Breathing
Engine Performance
Cylinder Head
Timing Mechanism
Engine Block
Summary
Review Questions
Chapter 2: Engine Repair and Rebuilding Industry
Terms to Know
Introduction
Full-Service Repair Facilities
Machine Shop and Engine Rebuild Facilities
Engine Repair and Replacement Specialty Facilities
Engine and Component Remanufacturing Facilities
Summary
Review Questions
Chapter 3: Theory of Engine Operation
Terms to Know
Introduction
Major Engine Components
Engine Operating Principles
Behavior of Liquids and Gases
Pressure and Vacuum
Boyle's Law
Engine Operation
Engine Classifications
Engine Vibration
Engine Displacement
Direction of Crankshaft Rotation
Engine Measurements
Other Engine Designs
Engine Identification
Summary
Review Questions
Chapter 4: Engine Operating Systems
Terms to Know
Introduction
The Starting System
Lubrication Systems
Cooling Systems
Cooling Fans
Lubrication and Cooling Warning Systems and Indicators
Fuel System
Automotive Fuels
Summary
Review Questions
Chapter 5: Factors Affecting Engine Performance
Terms to Know
Introduction
Spark Plugs
Combustion Chamber Sealing
Fuel and Combustion
Engine Noises
Summary
Review Questions
Chapter 6: Engine Materials, Fasteners, Gaskets, and Seals
Terms to Know
Introduction
Engine Materials
Manufacturing Processes
Fasteners
Gaskets, Seals, Sealants, and Adhesives
Summary
Review Questions
Chapter 7: Intake and Exhaust Systems
Terms to Know
Introduction
Air Induction System
Air Intake Ductwork
Air Cleaner/Filter
Intake Manifold
Intake Manifold Tuning
Vacuum Basics
Vacuum Controls
Turbochargers
Superchargers
Exhaust System Components
Mufflers
Summary
Review Questions
Chapter 8: Engine Configurations, Mounts, and Remanufactured Engines
Terms to Know
Introduction
Engine Configurations
Engine Mounts
Remanufactured Engines
Summary
Review Questions
Chapter 9: Cylinder Heads
Terms to Know
Introduction
Cylinder Heads
Cylinder Head Component Relationships
Combustion Chamber Designs
The Combustion Process
Multivalve Engines
Summary
Review Questions
Chapter 10: Camshafts and Valvetrains
Terms to Know
Introduction
Summary
Review Questions
Chapter 11: Timing Mechanisms
Terms to Know
Introduction
Valve Timing Systems
Chain-Driven Systems
Belt-Driven Systems
Gear-Driven Systems
Variable Valve Timing Systems
Variable Valve Lift (Cam-Shifting)
Variable Valve Timing and Lift Systems
Summary
Review Questions
Chapter 12: Engine Block Construction
Terms to Know
Introduction
Block Construction
Crankshaft
Camshaft
Lifter Bores
Harmonic Balancing
Flywheel
Short Blocks, Long Blocks, and Crate Engines
Summary
Review Questions
Chapter 13: Pistons, Rings, Connecting Rods, and Bearings
Terms to Know
Introduction
Bearings
Camshaft and Balance Shaft Bearings
Balance Shafts
Pistons
Piston Designs and Construction
Piston Rings
Connecting Rods
Summary
Review Questions
Chapter 14: Alternative Fuel and Advanced Technology Vehicles
Terms to Know
Introduction
Alternative Fuel Vehicle Use
Propane Vehicles
E85 and Flexible Fuel Vehicles
Compressed Natural Gas Vehicles
The Honda Civic GX CNG Vehicle
Electric Vehicles
Hybrid Electric Vehicles
HEV Operation
Plug-In Hybrid Electric Vehicles
Fuel Cell Vehicles
Summary
Review Questions
Glossary
Index
Shop Manual
Cover
Contents
Preface
Chapter 1: Safety and Shop Practices
Terms to Know
Introduction
Personal Safety
Lifting and Carrying
Hand Tool Safety
Power Tool Safety
Compressed Air Equipment Safety
Lift Safety
Jack and Jack Stand Safety
Engine Lift Safety
Cleaning Equipment Safety
Hazardous Waste
Vehicle Operation
Work Area Safety
Hybrid Vehicle High-Voltage Safety
ASE-Style Review Questions
ASE Challenge Questions
Chapter 2: Engine Rebuilding Tools and Skills
Terms to Know
Introduction
Units of Measure
Engine Diagnostic Tools
Exhaust Gas Analyzers
Engine Analyzer
Engine Measuring Tools
Special Hand Tools
Engine and Chassis Dynamometers
Special Reconditioning Tools and Equipment
Working as a Professional Technician
Service Information
ASE-Style Review Questions
Chapter 3: Basic Testing, Initial Inspection, and Service Procedures
Terms to Know
Introduction
Proper Vehicle Care
Writing a Service Repair Order
Test-Driving for Engine Concerns
Identifying the Area of Concern
ASE-Style Review Questions
ASE Challenge Questions
Chapter 4: Diagnosing and Servicing Engine Operating Systems
Terms to Know
Introduction
Battery Safety
Battery Testing
Battery Testing Series
Starting System Tests and Service
Lubrication System Testing and Service
Cooling System Testing and Service
Gallery and Casting Plugs
Leak Diagnosis
Warning Systems Diagnosis
ASE-Style Review Questions
ASE Challenge Questions
Chapter 5: Diagnosing Engine Performance Concerns
Terms to Know
Introduction
Spark Plug Evaluation and Power Balance Testing
Spark Plugs
Power Balance Testing
Exhaust Gas Analyzers
Engine Smoking
Improper Combustion
Compression Testing
Wet Compression Test
Running Compression Test
Cylinder Leakage Testing
Engine Noise Diagnosis
ASE-Style Review Questions
ASE Challenge Questions
Chapter 6: Repair and Replacement of Engine Fasteners, Gaskets, and Seals
Terms to Know
Introduction
Thread Repair
Gasket Installation
Cylinder Head Gasket Installation
Oil Pan Gasket Installation
Valve Cover Gasket Replacement
Seal Installation
Using Adhesives, Sealants, and Liquid Gasket Makers
ASE-Style Review Questions
ASE Challenge Questions
Chapter 7: Intake and Exhaust System Diagnosis and Service
Terms to Know
Introduction
Air Cleaner Service
Vacuum System Diagnosis and Troubleshooting
Vacuum Tests
Intake Manifold Service
Exhaust System Service
Turbocharger Diagnosis
Supercharger Diagnosis and Service
ASE-Style Review Questions
ASE Challenge Questions
Chapter 8: Engine Removal, Engine Swap, and Engine Installation
Terms to Know
Introduction
Preparing the Engine for Removal
Removing the Engine
Typical Procedure for RWD Engine Removal
Installing a Remanufactured Engine
Installing the Engine
Engine Start-Up and Break-In
ASE-Style Review Questions
ASE Challenge Questions
Chapter 9: Cylinder Head Disassembly, Inspection, and Service
Terms to Know
Introduction
Disassembling the Cylinder Head
Valve Inspection
Cylinder Head Inspection
Machine Shop Services
Straightening Aluminum Cylinder Heads
Resurfacing Cylinder Heads
Valve Guide Repair
Replacing Valve Seats
Refinishing Valves and Valve Seats
ASE-Style Review Questions
ASE Challenge Questions
Chapter 10: Valvetrain Service
Terms to Know
Introduction
Inspecting and Servicing the Valvetrain
Inspecting and Servicing Valvetrain Components, OHV Engine
Replacing Rocker ARM Studs
Cylinder Head Reassembly
Valve Adjustment
Adjusting Mechanical Followers with Shims
Adjusting Valve Clearance Using Adjustable Rocker Arms
On-Car Service
Valve Spring Replacement
ASE-Style Review Questions
ASE Challenge Questions
Chapter 11: Timing Mechanism Service
Terms to Know
Introduction
Symptoms of a Worn Timing Mechanism
Symptoms of a Jumped or Broken Timing Mechanism
Timing Chain Inspection
Timing Belt Inspection
Timing Gear Inspection
Sprocket Inspection
Tensioner Inspection
Timing Chain Guide Inspection
Reuse versus Replacement Decisions
Timing Mechanism Replacement
Timing Chain Replacement on OHC Engines
Timing Belt Replacement
Timing Chain or Gear Replacement on Camshaft-in-the-Block Engines
Timing Chain Replacement on Engines with OHC and Balance Shafts
Timing Chain Replacement on Engines with VVT Systems
ASE-Style Review Questions
ASE Challenge Questions
Chapter 12: Inspecting, Disassembling, and Servicing the Cylinder Block Assembly
Terms to Know
Introduction
Engine Preparation
Cylinder Head Removal
Timing Mechanism Disassembly
Engine Block Disassembly
Inspecting the Cylinder Block
Inspecting the Crankshaft
Inspecting the Harmonic Balancer and Flywheel
Servicing the Cylinder Block Assembly
Camshaft and Balance Shaft Bearing Service
Reconditioning Crankshafts
Installing Oil Gallery Plugs and Core Plugs
ASE-Style Review Questions
ASE Challenge Questions
Chapter 13: Short Block Component Service and Engine Assembly
Terms to Know
Introduction
Inspecting Crankshaft Bearings
Inspecting the Pistons and Connecting Rods
Piston Assembly Service
Engine Block Preparation
Installing the Main Bearings and Crankshaft
Installing the Pistons and the Connecting Rods
Completing the Block Assembly
Valve Timing and Installing Valvetrain Components
Checking and Adjusting Valve Clearance
Completing the Engine Assembly
ASE-Style Review Questions
ASE Challenge Questions
Chapter 14: Alternative Fuel and Advanced Technology Vehicle Service
Terms to Know
Introduction
Servicing Propane-Fueled Engines
Servicing CNG Vehicles
Servicing Hybrid Electric Vehicles
Servicing the Toyota Prius
Cooling System Service
Servicing the Honda Civic Hybrid
HEV Warranties
ASE-Style Review Questions
ASE Challenge Questions
Appendix A: ASE Practice Exam
Appendix B: Special Tools Suppliers
Appendix C: Manufacturers' Service Information Centers
Appendix D: Metric Conversion Charts
Appendix E: Engine Specifications Chart
Glossary
Index

Citation preview

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CLASSROOM MANUAL For Automotive Engine Repair & Rebuilding

SIXTH EDITION

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CLASSROOM MANUAL For Automotive Engine Repair & Rebuilding

SIXTH EDITION Chris Hadfield Director, Minnesota Transportation Center of Excellence

Randy Nussler South Puget Sound Community College & New Market Skills Center

Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Today’s Technician: Automotive Engine Repair & Rebuilding, Sixth Edition Chris Hadfield Randy Nussler SVP, GM Skills & Global Product Management: Jonathan Lau Product Director: Matthew Seeley Senior Product Manager: Katie McGuire Senior Director, Development: Marah Bellegarde Senior Product Development Manager: Larry Main

© 2018, 2014 Cengage Learning ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced or distributed in any form or by any means, except as permitted by U.S. copyright law, without the prior written permission of the copyright owner. For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, 1-800-354-9706

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Library of Congress Control Number: 2017930371

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Classroom Manual ISBN: 978-1-305-95811-1 Package ISBN: 978-1-305-95813-5

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Notice to the Reader Publisher does not warrant or guarantee any of the products described herein or perform any independent analysis in connection with any of the product information contained herein. Publisher does not assume, and expressly disclaims, any obligation to obtain and include information other than that provided to it by the manufacturer. The reader is expressly warned to consider and adopt all safety precautions that might be indicated by the activities described herein and to avoid all potential hazards. By following the instructions contained herein, the reader willingly assumes all risks in connection with such instructions. The publisher makes no representations or warranties of any kind, including but not limited to, the warranties of fitness for particular purpose or merchantability, nor are any such representations implied with respect to the material set forth herein, and the publisher takes no responsibility with respect to such material. The publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or part, from the readers’ use of, or reliance upon, this material.

Printed in the United States of America Print Number: 01

Print Year: 2017

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii CHAPTER 1 Automotive Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Terms to Know 1 • Introduction 1 • Basic Engine Operation 2 • Cooling System 6 • Lubrication System 6 • Engine Breathing 6 • Engine Performance 7 • Cylinder Head 9 • Timing Mechanism 10 • Engine Block 11 • Summary 12 • Review Questions 13 CHAPTER 2 Engine Repair and Rebuilding Industry . . . . . . . . . . . . . 15 Terms to Know 15 • Introduction 15 • Full-Service Repair Facilities 15 • Machine Shop and Engine Rebuild Facilities 17 • Engine Repair and Replacement Specialty Facilities 18 • Engine and Component Remanufacturing Facilities 19 • Summary 20 • Review Questions 20 CHAPTER 3 Theory of Engine Operation . . . . . . . . . . . . . . . . . . . . . 22 Terms to Know 22 • Introduction 23 • Major Engine Components 23 • Engine Operating Principles 27 • Behavior of Liquids and Gases 30 • Pressure and Vacuum 30 • Boyle’s Law 31 • Engine Operation 31 • Engine Classifications 34 • Engine Vibration 38 • Engine Displacement 40 • Direction of Crankshaft Rotation 42 • Engine Measurements 42 • Other Engine Designs 49 • Engine Identification 52 • Summary 56 • Review Questions 56 CHAPTER 4 Engine Operating Systems . . . . . . . . . . . . . . . . . . . . . . 59 Terms to Know 59 • Introduction 60 • The Starting System 60 • Lubrication Systems 65 • Cooling Systems 76 • Cooling Fans 88 • Lubrication and Cooling Warning Systems and Indicators 90 • Fuel System 94 • Automotive Fuels 98 • Summary 102 • Review Questions 103 CHAPTER 5 Factors Affecting Engine Performance . . . . . . . . . . . . 105 Terms to Know 105 • Introduction 105 • Spark Plugs 106 • Combustion Chamber Sealing 107 • Fuel and Combustion 111 • Engine Noises 115 • Summary 116 • Review Questions 116 CHAPTER 6 Engine Materials, Fasteners, Gaskets, and Seals . . . . . 118 Terms to Know 118 • Introduction 118 • Engine Materials 119 • Manufacturing Processes 122 • Fasteners 126 • Gaskets, Seals, Sealants, and Adhesives 131 • Summary 139 • Review Questions 139 CHAPTER 7 Intake and Exhaust Systems. . . . . . . . . . . . . . . . . . . . . 141 Terms to Know 141 • Introduction 141 • Air Induction System 142 • Air Intake Ductwork 143 • Air Cleaner/Filter 143 • Intake Manifold 146 • Intake Manifold Tuning 147 • Vacuum Basics 149 • Vacuum Controls 149 • Turbochargers 150 • Superchargers 155 • Exhaust System Components 159 • Mufflers 163 • Summary 165 • Review Questions 166 Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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CHAPTER 8 Engine Configurations, Mounts,

and Remanufactured Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Terms to Know 168 • Introduction 168 • Engine Configurations 168 • Engine Mounts 170 • Remanufactured Engines 172 • Summary 175 • Review Questions 175 CHAPTER 9 Cylinder Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 Terms to Know 177 • Introduction 177 • Cylinder Heads 178 • Cylinder Head Component Relationships 189 • Combustion Chamber Designs 190 • The Combustion Process 194 • Multivalve Engines 197 • Summary 198 • Review Questions 198 CHAPTER 10 Camshafts and Valvetrains . . . . . . . . . . . . . . . . . . . . . 200 Terms to Know 200 • Introduction 200 • Summary 214 • Review Questions 215 CHAPTER 11 Timing Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . 217 Terms to Know 217 • Introduction 217 • Valve Timing Systems 217 • Chain-Driven Systems 220 • Belt-Driven Systems 221 • Gear-Driven Systems 223 • Variable Valve Timing Systems 224 • Variable Valve Lift (Cam-Shifting) 226 • Variable Valve Timing and Lift Systems 226 • Summary 231 • Review Questions 231 CHAPTER 12 Engine Block Construction . . . . . . . . . . . . . . . . . . . . . 233 Terms to Know 233 • Introduction 233 • Block Construction 235 • Crankshaft 240 • Camshaft 245 • Lifter Bores 245 • Harmonic Balancing 245 • Flywheel 246 • Short Blocks, Long Blocks, and Crate Engines 247 • Summary 248 • Review Questions 248 CHAPTER 13 Pistons, Rings, Connecting Rods, and Bearings . . . . . 250 Terms to Know 250 • Introduction 250 • Bearings 250 • Camshaft and Balance Shaft Bearings 257 • Balance Shafts 257 • Pistons 257 • Piston Designs and Construction 263 • Piston Rings 266 • Connecting Rods 268 • Summary 270 • Review Questions 270 CHAPTER 14 Alternative Fuel and Advanced

Technology Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272 Terms to Know 272 • Introduction 272 • Alternative Fuel Vehicle Use 273 • Propane Vehicles 273 • E85 and Flexible Fuel Vehicles 276 • Compressed Natural Gas Vehicles 278 • The Honda Civic GX CNG Vehicle 283 • Electric Vehicles 284 • Hybrid Electric Vehicles 286 • Hev Operation 287 • Plug-In Hybrid Electric Vehicles 294 • Fuel Cell Vehicles 295 • Summary 295 • Review Questions 296

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

PREFACE

Thanks to the support the Today’s TechnicianTM series has received from those who teach automotive technology, Cengage Learning, the leader in automotive-related textbooks, is able to live up to its promise to provide new editions of the series every few years. By revising this series on a regular basis, we can respond to changes in the industry, changes in technology, changes in the certification process, and to the ever-changing needs of those who teach automotive technology. The Today’s TechnicianTM series features textbooks and digital learning solutions that cover all mechanical and electrical systems of automobiles and light trucks. The individual titles correspond to the ASE (National Institute for Automotive Service Excellence) certification areas and are specifically correlated to the 2016 standards for Automotive Service Technicians (AST), Master Automotive Service Technicians (MAST), and Maintenance and Light Repair (MLR). Additional titles include remedial skills and theories common to all of the certification areas and advanced or specific subject areas that reflect the latest technological trends, such as this updated title on engine repair. Today’s Technician: Automotive Engine Repair and Rebuilding, 6th edition, is designed to give students a chance to develop the same skills and gain the same knowledge that today’s successful technicians have. This edition also reflects the changes in the guidelines established by the National Automotive Technicians Education Foundation (NATEF). The purpose of NATEF is to evaluate technician training programs against standards developed by the automotive industry and recommend qualifying programs for certification (accreditation) by ASE. Programs can earn ASE certification upon NATEF’s recommendation. NATEF’s national standards reflect the skills that students must master. ASE certification through NATEF evaluation ensures that certified training programs meet or exceed industry-recognized, uniform standards of excellence. The technician of today and for the future must know the underlying theory of all automotive systems and be able to service and maintain those systems. Dividing the material into two volumes, a Classroom Manual and a Shop Manual, provides the reader with the information needed to begin a successful career as an automotive technician without interrupting the learning process by mixing cognitive and performance learning objectives into one volume. The design of Cengage’s Today’s TechnicianTM series was based on features that are known to promote improved student learning. The design was further enhanced by a careful study of survey results, in which the respondents were asked to value particular features. Some of these features can be found in other textbooks, while others are unique to this series. Each Classroom Manual contains the principles of operation for each system and subsystem. The Classroom Manual also contains discussions on design variations of key components used by the different vehicle manufacturers. It also looks into emerging technologies that will be standard or optional features in the near future. This volume is organized to build upon basic facts and theories. The primary objective of this volume is to allow the reader to gain an understanding of how each system and subsystem operates. This understanding is necessary to diagnose the complex automobiles of today and tomorrow. Although the basics contained in the Classroom Manual provide the knowledge needed for diagnostics, diagnostic procedures appear only in the Shop Manual. An

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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understanding of the underlying theories is also a requirement for competence in the skill areas covered in the Shop Manual. A spiral-bound Shop Manual delivers hands-on learning experiences with step-bystep instructions for diagnostic and repair procedures. Photo Sequences are used to illustrate some of the common service procedures. Other common procedures are listed and are accompanied with fine line drawings and photos that allow the reader to visualize and conceptualize the finest details of the procedure. This volume also contains the reasons for performing the procedures, as well as when that particular service is appropriate. The two volumes are designed to be used together and are arranged in corresponding chapters. Not only are the chapters in the volumes linked together, the contents of the chapters are also linked. The linked content is indicated by marginal callouts that refer the reader to the chapter and page where the same topic is addressed in the companion volume. This valuable feature saves users the time and trouble of searching the index or table of contents to locate supporting information in the other volume. Instructors will find this feature especially helpful when planning the presentation of material and when making reading assignments. Both volumes contain clear and thoughtfully selected illustrations, many of which are original drawings or photos specially prepared for inclusion in this series. This means that the art is a vital part of each textbook and not merely inserted to increase the number of illustrations. The layout of Automotive Engine Repair & Rebuilding, 6th edition, is easy to follow and consistent with the Today’s TechnicianTM series. Complex systems are broken into easier-to-understand explanations. Industry standardized terms and vernacular are used and explained in the text. Jack Erjavec

HIGHLIGHTS OF THE NEW EDITION—CLASSROOM MANUAL The Classroom Manual for this edition of Today’s Technician: Automotive Engine Repair and Rebuilding includes updated coverage of the NATEF AST, MAST, and MLR tasks for engine repair and rebuilding. In addition to updated coverage of industry trends, new information has been added on the following: ■ 0w16 oil ■ Engine design changes for gas direct injection (GDI) ■ EPDM belts ■ Stretch belts ■ Wet timing belts ■ Flat plane crankshafts ■ Cam-phaser design, operation, and service ■ Variable valve timing ■ Variable lift ■ Active fuel management ■ Variable cylinder displacement

HIGHLIGHTS OF THE NEW EDITION—SHOP MANUAL Like all textbooks in the Today’s TechnicianTM series, the understanding acquired by reading the Classroom Manual is required for competence in the skill areas covered in the Shop Manual. Service information related to the topics covered in the Classroom Manual Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

ix

is included in this manual. In addition, several photo sequences are used to highlight typical service procedures and provide the student the opportunity to get a realistic idea of a procedure. The purpose of these detailed photo sequences is to show students what to expect when they perform the same procedure. They can also provide a student with familiarity of a system or type of equipment they may not be able to perform at their school. To stress the importance of safe work habits, Chapter 1 covers safety issues and has been updated to include hybrid vehicle high-voltage safety. Included in this chapter are common shop hazards, safe shop practices, safety equipment, and the legislation concerning and the safe handling of hazardous materials and wastes. Chapter 2 covers special tools and procedures. Procedures include the use of engine condition and diagnostic test equipment, precision engine measuring tools and specialty measuring tools, along with engine reconditioning tools and equipment. The subsequent Shop Manual chapters synch up with those in the Classroom Manual, and the related content of each manual’s chapters is linked by use of page references in the margins. This allows the student to quickly cross-reference the theory with the practical. Redundancy between the Classroom Manual and the Shop Manual has been kept to a minimum; the only time theory is discussed again is if it is necessary to explain the diagnostic results or as an explanation of the symptom. Currently accepted service procedures are used as examples throughout the text. These procedures also served as the basis for the job sheets that are included in the textbook at the end of each chapter. Updated coverage in the Shop Manual addresses: ■ Engine pre-oiling ■ Engine break-in ■ 500-mile service for newly rebuilt engines ■ HEV service and safety ■ Concerns related to improper oil service on hydraulically controlled systems

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

x

CLASSROOM MANUAL Features of the Classroom Manual include the following:

CH AP TE R

3

THEORY O F ENGINE OPERATIO

N

Cognitive Objectives Upon comple tion

and review of this chapte r, you should Major engine understand component and be able s. Basic engine to describe: operation. compressio n ratio, eng ■ Basic ine efficiency laws of phy horsepower sics involved , and torque, engine ope wit horsepower h los ses ration. , mechanic al efficiency ■ Eng the , and ine classific rmal efficie ations accord ncy. the number ing to ■ The relationship of cycles, the between com cylinders, cyli number of ratio and eng nder arrange ine power out pression and valvetrai ment, ■ Mecha put. n type. nical, volum ■ The etric, and the four-stroke efficiencies, rmal cycle theory and factors ■ The . that affect each. different cyli nde r arrangeme and the adv ■ The nts antages of basic operati each. on of alterna ■ The engine des different valv tive igns, includ etrains used ing two-stroke modern eng diesel, and in ines. , stratified cha rge. ■ Eng ■ The ine measurem internal com ent terms suc ponents of bore and stro engine and a diesel h as how they diff ke, displacem er from tho of a gas eng ent, se ine. Terms To Kn ow

These objectives outline the chapter’s contents and identify what students should know and be able to do upon completion of the chapter. Each topic is divided into small units to promote easier understanding and learning.

■

■

Terms to Know List

Autoignition temperature Engine bea Bore rings Potential ene Friction Bottom dea rgy d center (BD C) Preignition Fuel injectio Boyle’s law n Reciprocating Glow plugs Brake horsep ower Reed valve Gross horsep Coil ower Rotary valv Horsepower Compressio e n-ignition (CI) engines Spark-ignition Hybrid electri (SI) engine c vehicle Compressio (HEV) Stroke n ratio Indicated hor Connecting Thermal effi sepower rods ciency Internal com Crankshaft Thermodyn bustion eng amics ine Kinetic ene Cycle Top dead cen rgy ter (TDC) Law of con Detonation Torque servation of energy Displacement Transmission Me cha nical efficie Dual overhe Transverse-m ncy ad cam ounted eng Net horsep (DOHC) ine ower Vacuum Overhead cam Engine Valve overlap (OHC) face Oving Efficiency erh Part ead valve (OH Volumetric V) efficiency (VE Piston rings ) Wrist pin

A list of key terms appears immediately after the Objectives. Students will see these terms discussed in the chapter. Definitions can also be found in the Glossary at the end of the manual.

256

Chapter 13

22

11_ch03_hr_02 2-058.indd 22

Cross-References to the Shop Manual References to the appropriate page in the Shop Manual appear whenever necessary. Although the chapters of the two manuals are synchronized, material covered in other chapters of the Shop Manual may be fundamental to the topic discussed in the Classroom Manual.

Margin Notes The most important terms to know are highlighted and defined in the margin. Common trade jargon also appears in the margin and gives some of the common terms used for components. This helps students understand and speak the language of the trade, especially when conversing with an experienced technician.

Bearing crown

A multipleFigure 13-10 ing. piece thrust bear

at the top e clearances ied. maintains clos Bearing crown re most of the loads are appl Figure 13-11 the bearing, whe and bottom of

inch mm) to 0.002 ons inch (0.0203 cificati ge of 0.0008 acturer’s spe within the ran ck the manuf clearances fall ical clearances; always che g rin bea oil typ haft or t the cranks These are just g on. r and protec (0.0508 mm). en the you are workin They are designed to wea to contaminated oil. Wh . rings. for the engine osure item bea r exp cam wea and a e and , eag main, rod Bearings are is after high mil to replace the rance to ensure that it y do wear out is customary it clea , airs the Shop camshaft. The rep ck the ssembled for l have to che apter 13 of wil disa Ch is in you ine ure gs, eng new bearin s this proced ing cus fitt dis l en wil Wh We cified range. within the spe Shop Manual e 588 Manual. Chapter 13, pag t are 0.001 and Bearings ize , bearings tha ers air serious to be usable and Ov ground to rep and polished Undersize haft has been generally available in worn lightly nks is t cra haf the nks If le. are When a cra e 0.050, often availab ese bearings lud are Th inc ize y ed. ers fitt ma 0.002 inch und ersize bearings can be tric undersized bearings of the bearings is und Me meter journal wear, h undersize. the inside dia ings and 0.030 inc means that 20, size 0.0 Undersize bear ls. der 10, rna Un 0.0 . jou e outside an oversized and 0.750 mm meter of the crankshaft have the sam dard line bored to 0.250, 0.500, dia 40 inch. ck has been diameter as stan bearthe reduced 0.030, and 0.0 These when the blo the smaller, to fit 0.010, 0.020, may be used bearings, but mm. in gs 00 le to rin er 1.0 ilab bea thick often ava 0.750, and e Oversize ing material is crankbearings are ly 0.250, 0.500, ring. The use of oversiz fit an undersize ter. Oversize gs are typical bea me rin d dia bea dar become ed al. stan shaft journ than the tric oversiz lacement has ped Available me side diameter tically as component rep rings are stam e a larger out ma bea e dra hav gs Som sed . rin in ons bea decrea rently ings are chining operati bearings has g that is cur Oversize bear dard and undersize ive than many complex ma ck the size of the bearin on it. Some thicker than stan ide che fect size correlation size bearouts more cost-ef technician to to increase the beartor y with the what that allows the from the fac cian indicate ped hni with a code tec type of diameter of the size stam e the this t helps rings com talled in ing to fit an over inside g on them tha rings are ins use. New bea The have a stampin erent sized bea it. bearing bore. same as engine blocks engine originally. If diff or remove diameter is the . rk ma the this on e ings change ing cam standard bear hnician should engine, the tec main ting rod and en most connec rication. Oft erience that or lack of lub been my exp ntaminated ted engine oil NOTE It has t-co ina ’S lan OR tam coo TH con AU the failure if it are caused by the oil pan, s in the ure ge of fail se g slud the cau bearin y r by the to determine failure is clea days, that ma the cause of crankcase. Try life of the engine; these the of oil in the the e to discuss oil, or the lack st bearings should last 0 km). Be sur Mo 02 to 321,87 . 1,4 ers (24 tom es is premature. cus mil r 0 to 200,000 nges with you reach 150,00 and filter cha of regular oil importance

Author’s Note This feature includes simple explanations, stories, or examples of complex topics. These are included to help students understand difficult concepts. PM 4/3/17 8:29

71.indd 256 h13 hr 250-2

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xi

110

Chapte

r5

Figure 5-8 cause the A pitted valve fac e allows valve to bu leakage tha rn. t wil

l eventually

Misadj tightly, it usted valves can also caus will be he e valve lea perform ld open an lo kage and strokes. ce through poor nger than it was burning. In designed If a valve se sive tem extreme cases, it aling of the co to. This is adjuste perature m ca can also d s. cause th bustion chambe n cause a reduct too e valves r during io to burn the appr n in if they ar opriate e expose d to exce s-

A Bit of History

A BIT O

FH

As recently ISTORY as early as as the mid-1980s , today’s en 60,000 or 75,00 it was not uncomm 0 mi gines can on for en gines to req run at lea les. Now due to adva st 150,000 uir miles befor nces in materials e valve recondition and ing e requiring valve servi machining, most of ce.

This feature gives the student a sense of the evolution of the automobile. This feature not only contains nice-to-know information, but also should spark some interest in the subject matter.

Head G

aske

58111_ ch05_h r_105-117 .indd 110

116

t Damag When a e head ga sket leaks context of , it can pr adjoinin combustion ch amber se esent a whole g cylinde host of aling , a rs. This significan different failu will tly sym also leak . This will caus lower the com re usually resu lts in a lea ptoms. In the pression e ou an to release t into the cool rough running and a lac d combustion k between two ing syste pressure of k m coolant leaking in and coolant. Th . This can caus of power. Combu both cylinders e the co e most co to the co stion ga ket failu oling sy ses can re m m stem pr mixing wi is the presence of bustion chambe mon symptom essure ca of a blow r. Anothe th coolant p n r in the oi situations the oil, and it will look l. The oi common sympt head gasket is , a compl l fo om dipstick of white ete engin amy and of head wi , sweet-s gasmelling e rebuild may be brownish, like a ll show signs of There is ex re co co ha qu ol ffe ust ant ire em a signific problem ant diffe to exit the tailpip d. This burning co ilkshake. In thes s ex rence in e e olant caus sible caus ist with combu cost, lab (Figure 5-9). es cloud sti es of low s with a re perform on chamber seali or, and techni qu ance, in alistic es ng e, . It de wi pending order to timate. on what offer the ll be your job to reco customer responsib gnize the posle repair options Chapter 5

2/13/17

er underlayer;

the copp worn down to on the left are om end. The bearings from the bott Figure 5-17 engine knocking these created

SUMMARY

Review Questions Short-answer essays, fill-in-the-blanks, and multiplechoice questions follow each chapter. These questions are designed to accurately assess the student’s competence in the stated objectives at the beginning of the chapter.

s that the mance require t its support engine perfor nd and tha ■ Proper chanically sou igned. engine is me des as g nin functio perly sealed systems are er must be pro bustion chamb formance. ■ The com d engine per ket seal to provide goo and head gas gs, rin g, es, spark plu ■ The valv chamber. tion ability to bus its es com crib the gasoline des the greater ane rating of the number, ■ The oct ng; the higher resist knocki ng. cki to kno the resistance

winter be used in the ity fuel should l should be Higher volatil volatility fue HC emisstarts; lower d ive col ess ist exc ass t to mer to preven used in the sum lock. es or are three typ sions and vap and detonation se serious preignition, ■ Misfire, that can cau combustion of abnormal . s can engine damage ling or lubrication system defects. ine in the coo or serious eng abnor■ Failures al combustion lead to cause abnorm l eventually wil r wea engine formance. ■ Normal reduced per mal noises and

■

ESTIONS REVIEW QU er Essays

Short-Answ

Summary Each chapter concludes with summary statements that contain the important topics of the chapter. These are designed to help the reader review the contents.

lanks ket can cause _________ gas t the ______ mance. 1. A leak pas engine perfor mis compro ed ___, ___ ___ ___ _________ ___ 2. The ______ ___ _______________, and plug rk ____________ ition to the spa mber. add in ___ ____________ l seal the combustion cha wal and cylinder system and ____________ engine ns in the ___ 3. Malfunctio ______ system can cause the _________ problems. mechanical are tion bus com al es of abnorm ______, and 4. Three typ ___,_________ occurs when a n ____________ ___. Preignitio spark. ____________ _________ the ___ ___ ts star flame front hole in the top ly to burn a like is ___ ___ 5. _________ of the piston.

Fill-in-the-B er? bustion chamb

l the com ponents sea 1. What com roper ur from imp blems can occ 2. What pro sealing? er mb cha combustion on engine e ned valve hav ct will a bur 3. What effe ? performance describe? ng octane rati s a gasoline’s an 4. What doe en fuel with can occur wh ms ble pro d? 5. What volatility is use inappropriate ignition. 6. Define pre onation. . 7. Define det combustion of abnormal some causes lead to? 8. Describe can detonation ms ble pro ine 9. What eng ? engine noises ses abnormal 10. What cau

PM 2/13/17 12:11

7.indd 116 _hr_105-11 58111 ch05

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

xii

SHOP MANUAL To stress the importance of safe work habits, the Shop Manual dedicates one full chapter to safety. Other important features of this manual include:

CHA PTE R 10

VALVETRAIN SERVIC E

Performance-Based Objectives

Basic Tools Lists

Upon completion and

review of this chapter, you should understand and be able to describ How to inspect the camsh e: aft for ■ How to recond straightness. Basic Tools ition rocker arms and replace studs. How to measure the camsh Basic mechanic’s aft lobes ■ How to evaluate and measu and journals and determ tool set re valve ine needed springs. repairs. Service manual ■ How to adjust ■ How to inspec the valvetrain during t solid and hydraulic installation of hydraulic lifters and determine neede lifters. d repairs. ■ ■ How to perfor How to adjust valve cleara m the leak-down test nces on on engines using mechanical hydraulic lifters and accura lifters. tely interpret the results. ■ How to prope rly reassemble the ■ How to inspec cylind er head. t the pushrods and determine needed repairs ■ How to install a cylinder head. . ■ How to descri ■ How to replac be the methods used e valve seals with the to correct rocker arm geom cylinder head installed etry. on the engine. 7 er Chapt that Terms To Know that there are no DTCs and harging system, be sure ■

These objectives define the contents of the chapter and what the student should have learned upon completion of the chapter.

Terms to Know List Terms in this list are also defined in the Glossary at the end of the manual.

Special Tools Lists Whenever a special tool is required to complete a task, it is listed in the margin next to the procedure.

■

322

Base circle Camshaft Duration Heel Leak-down Lifter

Each chapter begins with a list of the basic tools needed to perform the tasks included in the chapter.

intake air temperaOn a PCM-controlled turboc properly. A fault in the n systems are functioning re. Repair all related Lobe lift the fuel and ignitio PCM to limitreboost pressu example, could cause the Seat pressu Nose ture sensor, for . harger Spring mning the turboc free length malfunctions before conde Open pressure

Overlap er Removal Turbocharg Pushro

Spring shims

Spring squareness engine; for example, varies depending on the engine be erdsremoval procedure The turbocharg facturer recommends the Rocker arm Nissan 300 ZX, the manu a as such the turbocharger may , cars, ations some on other applic to the turbocharger. On removal proceremoved to gain access s follow the turbocharger Alway e. vehicl the in l turbocharger removed with the engine INTRODUCTIO be N The following is a typica facturer’s service manual. dure in the vehicle manu The valvetrain works to al procedure: remov open and close the valves cooling system. at the propeand run, the components of drain r time. Asthe the engine is batter y cable, the valvet negati rainthe wear nnect andvestretch 1. Disco . altered. , causin the valve harger openin pipe from thegturboc gand to the be engine block. Disconnect the exhaust This chapter discus2.ses t between the turbocharger the bracke metho rt suppo ds used the ve to inspect and repair housin 3. Remo semble the cylinder head, g on the turbocharger. adjust thevalves the oil drain back the valvetrain, reasremove bolts from , diagno se a failed thead at the block outlet, and worn valve stem seals on4. Removethe nut tube gasket inlet , and coolan the car.nnect replac harger e turboc theber, before deciding to rebuild compo as camshafts and lifters,5. Disco Remem nents such the cost of rebuil t. t bracke components. ding uppor compo related and t, nents must of replacing them. These the tube-s bracke be compa r box,red to the cost nt, air cleane components air usuall m eleme cleaneyrbe purchased cal connector, and vacuu rebuilding; however, there 6. Remove thecan electri new at bodyexpen le less se than linkage, thrott may be instan cesaccele the whenrator rebuilding is a viable option 7. Disconnect . e the three hoses. hose clamps, and remov inlet harger urboc y-to-t 8. Loosen the throttle-bod s. Remove the throttle body. manifold attaching screw throttle-body-to-intake on the compressor wheel harger discharge hose clamp 9. Loosen the lower turboc screw. Remove housing. and the fuel line bracket 441 screws anifold take-m pull the fuel rail and injec10. Remove the fuel-rail-to-in shield-retaining clips, and of wire. piece a two fuel-rail-bracket-to-heatwith the n 58128_ch10_hr_441-494.indd positio this 441 Tie the fuel rail in g. tors upward out of the way. housin line from the turbocharger 11. Disconnect the oil supply heat shield. old 12. Remove the intake manif harger and the water box. return line from the turboc line. Disconnect the coolant 13. er head and remove the 256 Chapter 13 bracket from the cylind Remove the line-support the exhaust manifold, and to retaining the turbocharger Special Tools turbocharger down14. Remove the four nuts manifold studs. Move the the from out of harger and up gauge turboc unit Pressure remove the vehicle, and then lift the ger side of the Parting face Hand pressure pump ward toward the passen t. Dial indicator the engine compartmen

ers after a turbocharger returning vehicles to custom e with them. Remind CUSTOMER CARE When maintenanc discuss proper care and shutting the vehicle replacement, be sure to before down wind the turbo to them that they should allow idle for a minute after drivthey should let the engine them that regular oil off. This simply means that You should also remind off. n ignitio the customer g Figureing turnin 13-10 before A multip can help ensure that the lepiece thrust bearinare turbocharger life. They changes g. essential to Bearing for turbocharger service. won’t be back anytime soon

crown Figure 13-11 Bearin g crown maintains close and bottom of the bearin clearances at the top g, where most of the loads are applied.

Shop Manual Chapter 13, page 588

oil bearingcharg ponent Inspection s er sCom Turbo clearance fall within the rang s turbocharger disassembly, inspect the wheel (0.0508 mm). Thes e of 0.0008 inch (0.02 er recommend with confactur are just lubric 03 or typic mm) If the vehicle emanu al clearance to ation Lack of lubricant 0.002 inch gs. for the s; alwaed. remov engine you ys chec housings are k the ending thework the end housin ons spec ufact rub urer’ wheel and shaft afterare on. g failure, which leads to man ificat ions Bear ings areoil s in .bearin a wear resultitem taminated They are designed camshaft. to wear and prote They do wear out after ct the crankshaft high mileage and expo engine is disassemb or sure to contaminated led for repairs, it is oil. When the customary to repla When fitting new ce the main, rod, and bearings, you will cam bearings. have to check the within the specified clearance to ensure range. We will discu that it is Manual. ss this procedure in Chapter 13 of the Shop

4/4/17 6:18

Undersize and Ove

Margin Note

rsize Bearings

The most important terms to know are highlighted and defined in the margin. Common trade jargon also appears in the margins and gives some of the common terms used for components. This feature helps students understand and speak the language of the trade, especially when conversing with an experienced technician.

Undersize bearings have the same outsid e diameter as standard bearings, but the bearing material is thicke r to fit an undersize crankshaft journal. Oversize bearings are thicker than standard to increase the outsid e diameter of the bearing to fit an oversize bearing bore. The inside diameter is the same as standard bearings.

When a cranksha ft is worn lightly and polished to be usab 0.002 inch undersize le, bearings that are are often available. 0.001 and If the crankshaft has journal wear, unde been ground to repa rsize bearings can ir serious be fitted. These bear 0.010, 0.020, and ings are generally 0.030 inch undersize available in . Metric undersize 0.250, 0.500, and 0.750 d bearings mm. Undersize mean smaller, to fit the redu s that the inside diam may include 0.050, ced diameter of the eter of the bear ings is crankshaft journals. Oversize bearings may be used when diameter. Oversize the block has been bearings are often line bored to an over available in 0.010 Available metric over sized , 0.020 sized bearings are , 0.030, and 0.040 typically 0.250, 0.500 bearings have a large inch. , 0.750, and 1.000 mm. r outside diameter than the standard These and undersize bear bearing. The use ings has decreased of dram over more cost-effective atically as compone size than nt replacement has become with a code that allow many complex machining operation s. Some bearings are s the technician to stamped check the size of the use. New bearings come stamped from bearing that is curre the factory with the ntly in engine blocks have size correlation on a stam it. Some ing came on the engin ping on them that helps the technicia n indicate what size e originally. If diffe engine, the technicia rent sized bearings bearare installed in this n should change this type of mark or remove it. AUTHOR’S NOT E It has been my experience that most bearing failures are connecting rod and caused by contamin main ated engine oil or the cause of failure lack of lubrication. is clear by the sludg Often e in the oil pan, the oil, or the lack of oil coolant-contaminate in the crankcase. Try d is premature. Mos to determine the caus t bear e of the failure if it reach 150,000 to 200,0 ings should last the life of the engin e; these days, that 00 miles (241,402 may to importance of regu lar oil and filter chan 321,870 km). Be sure to discuss the ges with your custo mers.

58111_ch13_hr_250-2 71.indd 256

Author’s Note This feature includes simple explanations, stories, or examples of complex topics. These are included to help students understand difficult concepts.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

xiii

Photo Sequences Many procedures are illustrated in detailed Photo Sequences. These photographs show the students what to expect when they perform particular procedures. They also familiarize students with a system or type of equipment that the school might not have.

14

Chapter 1

PHOTO SEQUENCE

2

Typical Procedure for

Lifting a Vehicle on a

P2-1 Drive the vehicle onto the sure your wheels are centered hoist. Make , and drive slow. If needed, stick your head out of the window or have an assistant help guide you. Never stand in front of a moving vehicle.

P2-4 Make sure that the locks are set and the hoist is level. Always rest the hoist on the locks. Most drive-on lifts are hydrauli cally lifted, but their locks are air operated .

Drive-On Hoist

P2-2 Place a wheel chock behind the other end of the vehicle to ensure it doesn’t roll when being lifted.

P2-5 Position the rolling jacks on a suitable location. Check the service manual for correct locations.

P2-3 Raise the vehicle to a comfortable height.

P2-6 Once the axle is to a height want it, lower it and rest it on the locks.s you151 ting System Most rolling era jacks are Opair operated and have manual locks.

vicing Engine

and Ser Diagnosing

NTINUED)

UENCE 5 (CO

PHOTO SEQ

References to the Classroom Manual t the P5-10 Reconnec

starter operates that the new king P5-11 Verify noise by cran without excess properly and a few times. the engine over

battery.

duce a highstarter will pro the starter Figure 1-12the essive, Typical jack stands. rs is exc too small, the two gea rned clearance is ce between n switch is retu cranked. If the itio ng ign bei is If the clearan the ine starts and while the eng r the engine pitched whine ed whine afte itch h-p hig will make a position. to the RUN a is too small 58128_ch01_hr_001-038.indd sing breakage have a little 14 se of drive hou ter to The major cau g gears. It is always bet SERVICE TIP ion and rin pin the n wee ce. clearance bet than too small a clearan ce more clearan Figure 1-11 Typical hydrauli c floor jack.

Service Tips Whenever a shortcut or special procedure is appropriate, it is described in the text. Generally, these tips describe common procedures used by experienced technicians.

LUBRICAT

ual Classroom Man e 60 Chapter 4, pag

D SERVICE TESTING AN ION SYSTEM

used to clearances Bearings are ent upon oil s created re is depend es excesTesting carr y the load ring becom life. Oil pressu forces. g ial to engine l and the bea by rotational ult of bearin ssure is essent rance between a journa r, are the res eve r. how wea Proper oil pre , clea p ons the deliver y. If ssure conditi de, and oil pum perapre gra oil oil er low and proper tem level, improp is lost. Not all of excessive sive, pressure ses include improper oil g oil as a result 632 cau er 13 re is thinnin wear. OtherChapt el will low oil pressu Too low a lev due mon cause of the oil level. Another com tion. ng y be cki ma it che h, dilu ted, begin by level is too hig tures or gas n misfire, e. If the oil ssure is suspec l pump, ignitio y, check 5 fue If low oil pre to aerate and lose volum d age pump result of a dam condition are satisfactor 3 nkcase as a cause the oil 1 testing is oil level and ering the cra Oil pressure e the to gasoline ent or engine flooding. If the t from the 4 rmin 2 8 used 6to dete r, bear re 7sending uni gauge to leaking injecto ssure gauge. pre condition of the re oil the oil pressu an nal using t the oil pressu test, remove and other inter nec re the ings oil pressure ssu con tch rs, pre an oil ine idles. Wa t size adapte ne components. eng rec engi cor the To perform as the the ge ng Increase Pulley erve the gau e 4-20). Usi temperature. engine (Figur Start the engine, and obs drops due to h the manuive wit ess e. ults exc sag res h the the oil pas are the test s to note any gauge. Comp cifications wit engine warm After gauge as the observing the provide oil pressure spe Bolt y warmed up. rs to 2,000 while engine rpm Manufacture be sure the engine is full confirm cifications. engine, and re; the rt sta t, facturers’ spe l operating temperatu sending uni re Water ma ssu nor pre at oil engine ll the pump plete, reinsta Intake the test is com

Oil Pressure

References to the appropriate page in the Classroom Manual appear whenever necessary. Although the chapters of the two manuals are synchronized, material covered in other chapters of the Classroom Manual may be fundamental to the topic discussed in the Shop Manual.

manifold

PM 4/4/17 4:49

Timing cover

indd 151 r_135-226. 58128_ch04_h

Front cover gasket Cylinder block

Figure 13-77 Water pump, pulley, and timing

Caution

Warnings and Cautions

Do not install the damper by striking it with a hammer. The damper or crankshaft may be damaged.

Cautions appear throughout the text to alert readers to potentially hazardous materials or unsafe conditions. Warnings advise the student of things that can go wrong if instructions are not followed or if an incorrect part or tool is used.

cover installation.

Figure 13-78 Intake manifold and typical

torque sequence.

(Figure 13-79). Most gasket s are marked to indicate proper direction for install After testing the fit, remov ation. e the intake gasket. Apply sealer at any locations direct the service manual. On V-type engines, the four ed in intersection points of the and the engine block usuall cylinder heads y require sealer. On V-typ e engines, locate the front end seals onto the block and rear . In addition, the intake manifold gasket may have tabs that must fit into the alignment head gasket for proper installation (Figure 13-80 The studs will hold the gasket ). in place while the manif engines. On V-type engine old is installed on most in-line s, the gasket may slip as the manifold is lowered prevent this, use an adhes into place. To ive to hold the gasket in place. position. Then install the Carefully lower the manif old into fasteners and torque to specifications. WARNING If the cylind er heads on a V-type engin intake manifold must be e have been machined, machined accordingly the so. Failure to machine manifold before reasse the intake mbly may cause oil and coolant leaks or consu well as reduced performan mption as ce. Refer to Chapter 9 for more information. On fuel-injected engines, install the fuel rail and the intake plenum and gasket the fasteners to the specif ied value. Next, install the . Torque throttle body assembly (Figur Make sure to replace e 13-81). the high-pressure (2,000 psi) fuel lines when instal camshaft-driven high-p ressure pump onto the ling the cylinder head of GDI (gasol injection) systems. ine direct Next, install the exhaust manifold and gasket. Replac with the exhaust manifold. e all mounting hardware The old fasteners may have used been weakened as a result of the

58128_ch13_hr_587-658.indd 632

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

xiv

Case Studies

570

Chapter 12

CASE STUDY

Each chapter ends with a Case Study describing a particular vehicle problem and the logical steps a technician might use to solve the problem. These studies focus on system diagnosis skills and help students gain familiarity with the process.

damr was excessively scuffed and block indicated that one cylinde customer. Inspection of a V8 engine and discussed them with the hed the options available to bore each cylinder having and e aged. The technician researc feasibl not of a new block was most It was decided that the cost e, it was decided that the ting of new pistons. In this instanc tion of a sleeve. After comple would require the purchase g the block was the installa to turn cost-effective method of repairin ons on the engine block, the technician was ready operati maining the of machin one all the required notes taken indicated that tion inspec s The haft. journal her attention to the cranks finish. All other main-bearing ian grinding to restore its surface fail in this manner, the technic bearing journals required l to have only one bearing l bearing was undersize origina the were good. Realizing it is unusua that red discove noise very closely and inspected the old bearing attempted to remove an engine not ground. Someone had the journal even though the journal was ce. The extra friction caused bearing to take up clearan all main-bearing journals were by simply installing a thicker haft position in the block, cranks were ces proper in clearan oil mainta to score. To were installed, and rd undersize, new bearings reputation ground to the next standa interest of the customer, your to find what is in the best checked. By taking the time grow. as an honest technician will

ASE-Style Review Questions

QUESTIONS ASE-STYLE REVIEW

the pistons should come 4. Technician A says that e the tightening out the top of the block. 1. Technician A says to revers cylinder head. the ing on the edge of the loosen drive to sequence when Technician B says to remove the pistons. the main caps starting piston skirt with a punch Technician B says to loosen and moving toward the t? correc at the front of the engine is Who C. Both A and B rear. A. A only D. Neither A nor B Who is correct? B. B only C. Both A and B only A. A removed for inspection. 5. The crankshaft has been D. Neither A nor B B. B only d the fillet is a aroun area the Technician A says cracks. you can pry most common location for stress 2. Technician A says that the number 1 with two big pry bars. ician B says a crack near harmonic balancers off Techn l may indicate a can damage the piston connecting-rod journa Technician B says that you protect the threads while faulty vibration damper. crankshaft if you do not using a puller. Who is correct? C. Both A and B Who is correct? A. A only C. Both A and B D. Neither A nor B A. A only B. B only Neither A nor B D. B. B only ready for inspection. 6. The cylinder block is warpage can be checked the engine to Technician A says that deck 3. Technician A says to rotate ing the timing and feeler gauge. using a precision straightedge TDC number 1 before remov bearing saddle ician B says that the main mechanism. Techn l or written ed with a precision menta a check be make to can ent says B alignm Technician . . marks gauge timing feeler a the of and n Name straightedge of the note ____locatio ________ ________ Who is correct? ________ Who is correct? ____B____ PERFORM C. Both A and B C. Both A and __ only A. ADa A. A only ING AN B te ______ er A nor B nor A OIL Neith Upon comp D. AN ________ D. Neith DerFILTER B. B only only letion of B B. ____ change. this job sh CH AN G eet, you sh E ould be ab JO B SH EE NATEF Co le to prope T rrelation rly perform an oil and This job filter sheet addre sses the fol lowing AS D.10. T/ MAST tas Perform engine oil k for Engin This job and filter e Repair: sheet addre change. sses the fol lowing M D.5. LR task for Perform Engine Re engine oil pair: and filter Tools an change. d Materia ls • Technic ian’s tool set • Shop rag • Correct type of en gine oil • Service manual • Oil filt er wrench • Used oil container • Torqu e wrench Describe the vehic le being worked on Year ____ ________ 189 : Systems ________ ing Engine Operating _ Make __ VIN ____ Diagnosing and Servic ________ ________ ________ ________ ___ Mod ________ Procedur el _ __ En ________ gine type e ________ and size __ ___ ________ Follow the NS ________ insLLEN tructionsGE QUESTIO ________ ASE CHA below to __ heater core may be complete 1. Pull the Technician B says that the es the engag it oil oil fill lev and filter ng noise when grindi a el g. r makes ch ind leakin an 1. A__starte ica ge tor (dipstic . Task Comp ________ k), __ teeth. leted an eel __ t? flywh d __ correc the ________ ednote the level andWho is __ ____ shimm ______ician co ition C. Both A and B ________ says that it could__be A __ ______ Techn A only of the oil. ________ A. nd ________ ______ ________ A nor B er Neith perly. __ D. impro __ __ __ __ ________ ________ ____gear could B only ______ __ says _____ starter drive ________ B. ____that ____the ician B__ ng ________ ________ 2. WTechn that his oil pressure warni ______ ________ hat are the says er__ 4. A custom ged. _______ ________ be dama oil AP An . I idling an is ma car d __ nual for the SAE rat ______light s on while the come ______ cot? rrect infor ings for the oil yo ________ Who is correc ____ _____low oil pressure. matio uBare going test shows ________ re and A pressu n)? Both C. to use (co may be A. A only ______________ nsult that the engine bearings says theAser ician __D. Techn ____ ________ er A nor B Neith vice ______ ________ ________ B. B only ________ ________ worn. ________ ________ 3. Warm t draw ____curren the oil pressure relief valve ______ that the engin starter says a B __ ming ician __ perfor __ Techn __ is ___ ________ e to opera technician plu2.g A is rem ________ be stuck closed tingwill . turn over. The test ovedse temnot perat ________ . the engine may ure. Ththe test becau _______ e starter 4. Properl flow faster Who is correct? te that the current draw on oil willthe: y raiseindica results when the the vehicl ication. This means that drain C. Both A and B on a lift 5. Place is higher than theespecif . A. A only h the used oilrco D. Neither A nor B plug, anA. nta id is bad. soleno d letstarte B. B only the oil flo iner (or catch basin container w intcharg ) un ing. o de move from be the r needs y cause the the h gauge does not engine. B. batter t temperature flow rate container. You ma drain plug. Re5.mo coolan A and posit y ve the drain the vehicle is driven. n switch is bad. ion will ch have to adjust the its lowest reading when 6. Now remC. ignitio an posit h . ge as more ion of the rature locked tempe lly t statica ove engin coolan the hydro oil may be flows A says that panels. MD. the oile filt Techn out ician of the ake sure all er. You may ha nected. of the oil pressuve to uswith pressure sensor wires may be discon e a spaec ws intrized ial wrench ostat could be 3. A cooling system isflo therm o theminut the that the says B es, us or ed oil conta removTechn 15 e someician iner. tester to locate a leak. After stuck open. from 15 psi to 5 psi, h tester gauge has dropped leaks in the engine Who is correct? and there are no visible C. Both A and B A. A only compartment. engine may have an D. Neither A nor B 197 Technician A says that the B. B only leak. t gaske 197 internal head

Each chapter contains ASE-Style Review Questions that reflect the performance objectives listed at the beginning of the chapter. These questions can be used to review the chapter as well as to prepare for the ASE certification exam.

Job Sheets

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ASE Challenge Questions Each technical chapter ends with five ASE challenge questions. These are not more review questions; rather, they test the students’ ability to apply general knowledge to the contents of the chapter. 8128_ch04 _hr_135 -226.ind d

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Located at the end of each chapter, the Job Sheets provide a format for students to perform procedures covered in the chapter. A reference to the NATEF Tasks addressed by the procedure is included on the Job Sheet.

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SUPPLEMENTS Instructor Resources The Today’s TechnicianTM series offers a robust set of instructor resources, available online at Cengage’s Instructor Resource Center and on DVD. The following tools have been provided to meet any instructor’s classroom preparation needs: ■ An Instructor’s Guide including lecture outlines, teaching tips, and complete answers to end-of-chapter questions. ■ PowerPoint presentations with images and animations that coincide with each chapter’s content coverage. ■ Cengage Learning Testing Powered by Cognero® provides hundreds of test questions in a flexible, online system. You can choose to author, edit, and manage Test Bank content from multiple Cengage Learning solutions and deliver tests from your LMS, or you can simply download editable Word documents from the DVD or Instructor Resource Center. ■ An Image Gallery includes photos and illustrations from the text. ■ The Job Sheets from the Shop Manual are provided in Word format. ■ End-of-chapter Review Questions are provided in Word format, with a separate set of text rejoinders available for instructors’ reference. ■ To complete this powerful suite of planning tools, correlation guides are provided to the NATEF tasks and to the previous edition.

REVIEWERS The author and publisher would like to extend special thanks to the following instructors for reviewing this material: Matthew Bockenfeld Vatterott College—Joplin Joplin, MO David Chavez Austin Community College Austin, TX Joseph Cortez Reynolds Community College Richmond, VA Jason S. Grice Black Hawk College Galva, IL

Todd Mikonis Manchester Community College Manchester, NH Vincenzo Rigaglia Bronx Community College Bronx, NY Ronald Strzalkowski Baker College of Flint Flint, MI Michael White The University of Northwestern Ohio Lima, OH

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 1

AUTOMOTIVE ENGINES

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■

The purpose of the automotive engine. The basic operation of the internal combustion four-stroke engine. The basic function of the cooling and lubrication systems. The basic function of the intake and exhaust systems.

■ ■ ■

The basics of the cylinder head and its related components. The engine block and its related components. Many of the major components of the engine.

Terms To Know Camshaft Combustion Combustion chamber Cylinder Cylinder head Engine block Exhaust manifold

Intake manifold Internal combustion engine (ICE) Journals Overhead camshaft (OHC) engine Piston

Powertrain Powertrain control module (PCM) Pushrod Thermostat Valve timing Valvetrain

INTRODUCTION The automotive engine is the power source that drives the automobile. Today’s engines are capable of providing good performance and smooth operation in a variety of ambient pressures and temperatures while accelerating, decelerating, cruising at high speeds, or at idle. They also achieve good fuel economy and low toxic emissions. While the basic operation of the four-stroke gasoline internal combustion engine (ICE) has not changed in more than 100 years, efficiency and power ratings have increased more than 1,000 percent. Henry Ford’s Model T sported a 2.7-L engine producing about 20 horsepower (hp). Today we commonly see more than 300 hp out of the same size engine. Refinements to the base engine and its support systems have allowed the gains in performance, control of fuel consumption, and emissions. Lighter materials within the engine have allowed weight reductions. The precision and accuracy of the manufacturing process of modern engines have increased, allowing tighter engine internal clearances. The durability of engines has increased also due to improvements in the process of manufacturing materials and metals. With proper maintenance, most engines should provide more than 150,000 miles of trouble-free service. Improved parts, new component designs, advanced fluids, and electronic controls have allowed for fewer maintenance

Internal combustion engine (ICE) burns its fuels within the engine. The power that is used as a result of burning that fuel is also developed inside the engine. In comparison, in an external combustion engine the burning of fuel occurs in an external source, or tank. The heat is then transferred to a separate component where it can be used to power the engine and move parts. Examples of external combustion engines would be steam locomotives and the Stirling engine.

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Figure 1-1 Today’s smaller engines can produce some hefty horsepower. A powertrain includes the engine and all the components that deliver that force to the road, including the transmission and axles. The combustion chamber is a sealed area in the engine where the burning (combustion) of the air and fuel mixture takes place. The piston is a roundshaped part that is driven up and down in the engine cylinder bore. An engine cylinder is a round hole bored into the cylinder block. The pistons are housed in the cylinders. The powertrain control module (PCM) is an onboard computer that controls functions related to the powertrain, such as fuel delivery, spark timing, temperature, and shift points. Combustion is the controlled burn created by the spark igniting the hot, compressed air and fuel mixture in the combustion chamber.

requirements. Powertrains are now more than 95 percent cleaner in terms of toxic emissions than those of the 1960s, while the number of vehicles on the road has more than doubled. This text will focus on the operation and service of these powerful and efficient new gasoline engines (Figure 1-1). You must thoroughly understand the operation of the engine and the functions of its components to become a skilled automotive diagnostic and repair technician. To provide good customer service and ensure proper engine performance, you must accurately diagnose faults and perform precise repairs of the engine and its supporting systems. This chapter will highlight the contents of the classroom and shop manuals. Each chapter in the classroom manual will explain the theory and operation of a system. The corresponding shop manual chapter will describe the diagnostic and repair procedures and strategies for those systems.

BASIC ENGINE OPERATION The gas engine is often described as an air pump because it uses a tremendous amount of air. But to make power, it also uses a small percentage of gasoline. The engine pulls air into a sealed combustion chamber through the intake system. The combustion chamber is sealed on the bottom by the piston and its rings (Figure 1-2) and on the top by the combustion chamber formed in the cylinder head (Figure 1-3). Air enters into the cylinders as the pistons move downward. This creates a difference in pressure between the cylinder and the atmosphere. The lower pressure area is in the cylinder. When the intake valve opens, the atmospheric pressurized (fresh) air rushes into the cylinder via the intake manifold. Fuel is injected into the airstream near (or sometimes in) the combustion chambers. The timing and quantity of fuel delivery are precisely controlled by the powertrain control module (PCM). The air and fuel mixture is then compressed to make it more combustible as the piston moves toward the top of its travel. At the optimum instant, the PCM initiates ignition that will deliver a spark to the spark plug. When the spark jumps across the gap of the spark plug, the air and fuel mixture is ignited and burns rapidly, and the engine harnesses some of the heat energy available in the fuel. This rapid, but controlled, burning is called combustion. The power of the expanding gases pushes down with a force comparable to an elephant standing on top of the piston. The piston is connected to the crankshaft by a

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Automotive Engines

Figure 1-3 The bottom of this cylinder head (shown) shows the four combustion chambers sealed by the valves.

Figure 1-2 This piston and rings, with the connecting rod attached, fit closely in the engine cylinder to seal the bottom of the combustion chamber.

connecting rod (Figure 1-4). The crankshaft causes the engine to turn. Then the spent gases are allowed to exit the combustion chamber through the exhaust system. This process is repeated in each of the engine cylinders to keep the crankshaft spinning. The engine valves allow airflow into and out of the combustion chamber. There are typically one or two intake valves per cylinder and one or two exhaust valves per cylinder (Figure 1-5). Refer to Figure 1-3 to see the heads of the valves within the combustion chamber. The valves are opened by the camshaft (Figure 1-6). The camshaft is a gear, belt, or chain driven by the crankshaft. The relationship between the camshaft and crankshaft rotation creates the proper valve timing. It is carefully timed to ensure that the valves open at the correct time. The camshaft has egg-shaped (or cam-shaped) lobes on it to force the opening of the valves. Valve springs close the valves.

The camshaft is a shaft with eccentrically shaped lobes on it to force the opening of the valves. Valve timing refers to the relationship between the rotation of the crankshaft and camshaft. That correct relationship ensures that the valves open at the correct time.

Connecting rod

Figure 1-4 The connecting rod connects the piston to the crankshaft.

The crankshaft and connecting rod work together to change the reciprocating and linear motion of the piston into the rotary motion of the crankshaft.

Figure 1-5 An engine valve.

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Figure 1-6 The camshaft has large, round journals that fit into bearings in the block and small, eccentrically shaped lobes that open and close the valves.

Figure 1-7 This transversely mounted engine sits sideways in the engine compartment with the transaxle bolted on its end.

Engine Location Most engines are installed in the front of the vehicle. They may be installed longitudinally, with the front of the engine toward the bumper and the rear toward the passenger compartment, or transversely, with the engine placed in the engine compartment sideways. Trucks and rear-wheel drive (RWD) vehicles most commonly use a longitudinally mounted engine. Many passenger vehicles and most front-wheel drive (FWD) vehicles use a transversely mounted engine (Figure 1-7). This design allows a shorter hood line, desired in today’s vehicles to provide greater passenger space. A few vehicles use a mid-engine design, where the engine is placed between the rear axle and the driver. Often, this well-balanced configuration is associated with modern sports cars. Engines are held in place by motor mounts. These are attaching pieces with a flexible rubber portion that isolates much of the engine vibration from the automobile frame and passenger compartment. The mounts connect the engine to the vehicle chassis (Figure 1-8).

Engine Function The engine is attached to the transmission through the flywheel and clutch on a manual transmission (Figure 1-9) or through the flexplate and torque converter on an automatic transmission. The engine delivers rotational speed and a twisting force Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Automotive Engines

Rubber bushing Engine mount

Figure 1-8 The engine mount has a rubber bushing to isolate the vibration of the engine from the chassis.

Figure 1-9 The flywheel bolts to the crankshaft and is attached to the transmission through the clutch on a manual transmission.

to spin the transmission components. The twisting force is called torque, and the speed that develops is called horsepower. The transmission uses this torque and horsepower and manipulates them to provide the appropriate level of torque and speed to drive the wheels and propel the vehicle. The transmission multiplies the torque of the engine through gear sets in the transmission and differential to allow for good acceleration. In higher gear(s), torque is reduced and speed is increased to improve fuel economy. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 1-11 The head gasket seals between the block and the cylinder head. Figure 1-10 A thermostat.

COOLING SYSTEM

A thermostat is a mechanical component that blocks or allows coolant flow to the radiator.

Combustion develops a tremendous amount of heat in the engine. The expansion of gases from the heat pushes the piston down, but some of the heat is absorbed in the engine components. A liquid cooling system is used on all current gas automobile engines to remove excess heat from the engine. An engine belt or gear drives a water pump that circulates coolant throughout the engine to keep all areas at an acceptable temperature, around 200°F (110°C). When the coolant reaches a certain temperature, a thermostat (Figure 1-10) opens to allow coolant to flow through the radiator to cool it down. Air flowing across the radiator lowers the temperature of the coolant; then the water pump pulls the coolant back into the engine and recirculates it. The cooling system must retain heat to speed the warmup period to enhance combustion and lower emissions after cold starts. It must also maintain an even engine operating temperature for better engine efficiency. To prevent the meltdown of components, the cooling system must remove excess heat. Cooling system problems can cause very serious damage to an engine. Heat expansion of parts can cause the engine to seize. When an engine overheats, it is likely to blow the seal between the cylinder head and the cylinder block. That seal is the head gasket, and replacement can cost several hundred dollars or more and many hours of work (Figure 1-11).

LUBRICATION SYSTEM The lubrication system is critical to reduce the tremendous friction created between the moving components in the engine. This also reduces engine heat and wear. The oil pump is mounted on the bottom of the engine or on the crankshaft to circulate engine oil under pressure to all friction areas in the engine (Figure 1-12). The oil is then filtered to remove particles of metal or debris that could damage finely machined engine components. The oil travels through oil passages drilled throughout the engine to reach the crankshaft, the camshaft, the cylinder walls, and other key friction areas. Just a few minutes of engine operation without adequate lubrication can turn an engine into irreparable scrap metal. Proper lubrication system maintenance is essential to the longevity of any engine.

The intake manifold connects the air inlet tubes to the cylinder head ports to equally distribute air to each cylinder.

ENGINE BREATHING Engine power is dependent on how well the engine can breathe. The intake and exhaust systems provide the breathing tubes for the engine. The intake manifold connects the air intake ductwork to the cylinder head (Figure 1-13). The intake manifold distributes an equal amount of air to each cylinder. Ports into the combustion chamber allow fresh Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Automotive Engines

Figure 1-12 This oil pump is driven off of the front of the crankshaft.

Figure 1-13 The intake manifold distributes air equally to the cylinders. Note that this is for an eight-cylinder engine.

air to flow past the intake valves when they are open. The exhaust manifold connects the exhaust ports on the cylinder head to the rest of the exhaust system. To a major degree, the more air an engine can take in, the more power it can put out. The intake and exhaust systems must flow freely to allow good airflow. Turbocharging and supercharging are systems that increase airflow by forcing air under pressure into the intake. These systems dramatically increase engine power (Figure 1-14). Problems with the engine’s ability to breathe significantly affect engine performance. Something as simple as a restricted air filter can cause the engine to barely run or even to not start. You will learn simple maintenance procedures for the intake and exhaust systems, as well as more sophisticated tests to diagnose tricky problems.

The exhaust manifold connects to the cylinder head and acts as a chamber to let exhaust gases exit the engine in an efficient and safe manner.

ENGINE PERFORMANCE An engine has many required conditions to function as designed and deliver good performance. An engine needs to have the combustion chamber well sealed to develop compression of the air and fuel mixture. The engine and intake system must be large enough to Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 1-14 This supercharger creates powerful boost and acceleration.

accommodate and sealed tightly enough to maintain the low pressure needed for the exchange of exhaust gases and fresh air in each cylinder for the engine’s given displacement. The lubrication and cooling systems must be operating properly. Each engine component must be within its operating tolerance to allow the engine as a whole to hold together and run well (Figure 1-15). Problems in how the engine performs will keep you busy as an engine technician. To recommend repairs, you will need to learn how to evaluate the engine’s mechanical condition. Vacuum tests and compression tests as well as listening and smelling will be some of the weapons in your arsenal to correctly diagnose the cause of engine problems (Figure 1-16). You must test and cross-check before you recommend major engine repairs, trying to gather as much information as possible. You’ll need a detailed diagnosis to be able to offer the customer an accurate estimate and to

Figure 1-15 This severely worn lifter would cause poor engine performance.

Figure 1-16 You will learn many different ways to analyze the engine.

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Automotive Engines

be sure you correct the problem on the first try. Engine repairs can become very costly; therefore, it is crucial that the diagnosis and repairs are performed with care and attention to detail.

A cylinder head is the large object that houses most of the valve train and covers the combustion chamber.

CYLINDER HEAD If a cylinder head contains the camshaft, it is called an overhead camshaft (OHC) engine. The camshaft can also be located in the cylinder block.

The cylinder head houses the valves and often the camshaft. In this case it is called an overhead camshaft (OHC) engine (Figure 1-17). In cases where the camshaft is in the block, the cylinder head still holds many of the valvetrain components. The pushrods, lifters, rocker arms, and springs are all parts of the valvetrain because they work to open and close the valves. When the camshaft is in the block, as the high point of the camshaft lobe comes up, it pushes on a lifter, which acts like a plunger, to move the pushrod. The pushrod is a simple, hollow rod that transfers the motion from the lifter to the rocker arm. The rocker arm rides on a pivot. When the pushrod raises one end of the rocker, the other end pushes down on the tip of the valve to open it, much like a typical first-class lever (Figure 1-18). In later chapters you will discover there are many different combinations that the camshaft can be used in. Problems within the cylinder head and valvetrain can be quite serious. A valve that is not adjusted properly, for example, can cause that cylinder to drop in performance, become noisy, and cause the engine to run rough. During an engine overhaul, it is typical to perform a valve job. This involves refinishing all the valves and their seats and replacing the valve seals. This requires complete disassembly of the cylinder head and some precision machining and repair (Figure 1-19).

The valvetrain is made up of the components that open and close the valves. A pushrod is a long tube that connects that camshaft to the valve train components in the cylinder head. This is typically not used on an OHC engine.

Fulcrum (Pivot point)

Rocker arm Valve spring

Valve guide

Valve

Pushrod

Lifter

Camshaft Rocker arms

Figure 1-17 This OHC engine uses rocker arms to open the valves.

Figure 1-18 The valvetrain components open the valve in response to the camshaft lobe.

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Figure 1-19 You will learn to use specialized equipment used in engine overhauling, such as this valve grinder.

TIMING MECHANISM As discussed earlier, proper valve timing is necessary to keep the valves opening and closing at the correct times. This is achieved by the timing mechanism. A sprocket or gear on the crankshaft is attached by a gear, belt, or chain to a sprocket or gear on the camshaft (Figure 1-20). Timing belts require periodic maintenance. When that is neglected, the timing belt can snap, and serious engine damage can result. In some cases, the valves contact the top of the pistons and bend, and a new set of valves is required (Figure 1-21).

Figure 1-20 The lower crankshaft gear turns at twice the speed of the larger camshaft gear.

Figure 1-21 Valve timing failures can be catastrophic.

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Automotive Engines

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In the worst cases, those valves damage the piston tops, and the whole engine needs to be overhauled. Timing chains also wear out over time, and replacing them requires skill and attention to detail. Variable valve timing systems increase performance and minimize emissions. More and more vehicles employ these systems to vary the times when the valves can be opened. This makes timing mechanism theory and service a new and more complex challenge.

ENGINE BLOCK The engine block is the main supporting structure of the engine (Figure 1-22). It holds the pistons, connecting rods, crankshaft, and sometimes the camshaft. The cylinder head bolts to the top of the block. The block is bored (drilled) to create cylinders. An eight-cylinder engine has eight-cylinder bores (Figure 1-23). The pistons are pushed up and down in the cylinders by the crankshaft. On the power stroke, the piston is actually pushed down by the force of combustion to turn the crankshaft. Rings on the pistons seal the small clearance between the cylinder walls. This prevents the hot, expanding gases from combustion within the combustion chamber, which lets all the force act to push the piston down. The rings also scrape excess oil from the cylinder walls so the oil does not burn inside the combustion chamber. When oil is allowed to burn during combustion, it forms blue smoke that exits the tailpipe. The block also holds the crankshaft in its main bore. The soft main bearings are placed within the main bore to provide a place for the finely machined crankshaft journals to ride. The journals are the machined round areas of the crankshaft that allow the bearings and bearing caps to bolt around them and hold the crankshaft in the engine block. The clearance between the journals and the bearings must be just right: enough to allow adequate oil, but not so much that precious oil pressure leaks through excessive clearances. Crankshaft bearings of the friction type are softer than the metal they support. Bearings protect the crankshaft from damage, but they also wear. When they wear excessively, they cause low oil pressure and engine knocking.

Figure 1-22 An eight-cylinder engine block.

The engine block is the main structure of the engine that forms the combustion chamber and houses the pistons, crankshaft, and connecting rods.

Main journals are round machined portions on the centerline of the crankshaft where the crankshaft is held in the main bore.

Figure 1-23 The cylinder bores are finely finished to provide a good sealing surface for the rings.

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Figure 1-24 This carriage is powered by one of Daimler’s first engines.

A BIT OF HISTORY Jean-Joseph Lenoir created the first workable internal combustion engine in 1860. Nicholas Otto was credited with creating the first four-stroke internal combustion engine back in 1876. All previous internal combustion engines did not compress the air-fuel mixture. They attempted to draw the air-fuel mixture in during a downward movement of the piston and then ignite the mixture. The expansion of gases would force the piston down the rest of its travel. This design was used to make the piston forceful on each downward stroke. The four-stroke engine, however, proved much more efficient and powerful. Gottlieb Daimler received the first patent for the internal combustion engine in 1885. The basic operation of today’s engines is still similar to those first four-stroke engines. Figure 1-24 shows an early working model from Daimler’s workshop, which is now a museum.

An engine overhaul involves rebuilding the engine to nearly new condition. Each step of engine repair requires careful inspection, measurement, and judgment. Together the Today’s Technician Engine Repair & Rebuilding Classroom and Shop Manuals provide the information needed to learn about component theory, operation, diagnosis, and the repair procedures of modern engines. The text covers information on principles, safety, the engine repair industry, ancillary systems, diagnosis, measuring and testing, removal, service, installation, along with alternative fuel vehicle operation and service.

SUMMARY ■

■ ■

Today’s smaller engines make more power with longer life, fewer emissions, and better fuel economy than their older counterparts. The powertrain control module controls the engine’s operation. The engine ignites a compressed air and fuel mixture in a confined chamber to harness the heat energy of expanding gases.

■

■

■

The power of combustion pushes down on the piston. The piston is connected to the crankshaft by the connecting rod. The intake and exhaust systems allow the engine to take in and expel the great quantity of air that the engine needs to make power. The cooling system prevents the meltdown of engine components.

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Automotive Engines ■ ■ ■

The lubrication system reduces temperature and friction in the engine. The cylinder head houses the valvetrain that opens and closes the engine valves. The camshaft controls the operation and timing of the valves. It can be used in different configurations.

■

■

13

The cylinder block holds the pistons, connecting rods, and crankshaft and provides the main structure of the engine. All of the engine systems and components must work together as designed to create a smoothrunning engine that has sufficient power and produces low emissions.

REVIEW QUESTIONS Short-Answer Essays 1. Explain the benefits of today’s modern engines. 2. Explain what the combustion chamber is. 3. How does fresh air enter the cylinders?

8. The _______________ and _______________ are compressed in the combustion chamber. 9. The _______________ both opens and closes the valves.

4. What controls fuel injection and spark timing?

10. The _______________ _______________ holds the crankshaft in its main bore.

5. What is the function of the intake manifold?

Multiple Choice

6. Where can an oil pump be mounted? 7. How does a turbocharger create more power? 8. What is valve timing? 9. Name three components located in the engine block. 10. What forces the crankshaft to turn?

Fill-in-the-Blanks 1. The _______________ of modern engines have decreased more than 90 percent from earlier models. 2. A difference in air pressure produces the movement of fresh air into the _______________ through the intake system. 3. The PCM controls _______________, _______________, and _______________, _______________ among other functions. 4. The _______________ _______________ distributes air equally to each cylinder. 5. The oil pump may be driven off the front of the _______________. 6. When the thermostat opens, coolant flows through the _______________. 7. The _______________ _______________ connects the cylinder head to the exhaust system.

1. Today’s powertrains require: A. more maintenance. C. more fuel. B. bigger engine sizes. D. less fuel. 2. The engine is often described as a(n): A. water pump. C. impeller. B. air pump. D. gear driver. 3. Technician A says that the more air an engine can take in, the more power it can put out. Technician B says that the exhaust can affect how well an engine can breathe. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. Technician A says that the piston is connected to the crankshaft by the rocker arm. Technician B says that the connecting rod converts the reciprocating motion of the piston to the rotary motion of the crankshaft. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. The cylinder head forms the top of the: A. cylinder. B. combustion chamber. C. intake manifold. D. throttle bore.

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Chapter 1

6. When a spark ignites the air and fuel mixture, _______________ occurs. A. an explosion C. conflagration B. a blast D. combustion 7. The _______________ is the main supporting structure of the engine. A. motor C. cylinder head B. block D. main bore 8. Technician A says that the main bearings protect the crankshaft journals. Technician B says that the camshaft lobes lift the pistons. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

9. Which of the following is true? A. The crankshaft rotates at the same speed as the camshaft. B. The camshaft rotates twice as fast as the crankshaft. C. The camshaft rotates three times as fast as the crankshaft. D. The crankshaft rotates twice as fast as the camshaft. 10. Valve timing is: A. when the spark occurs. B. when the pistons rotate. C. when the valves open and close. D. how long combustion takes.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 2

ENGINE REPAIR AND REBUILDING INDUSTRY

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■

What types of repair are performed at a full-service repair facility. The reasons for the existence of specialty shops and repair facilities. What changes are occurring in the engine repair and rebuilding industry.

■ ■ ■

The skills needed for employment in various settings. How specialized repair facilities operate. The basic engine rebuilding process at a remanufacturing facility.

Terms To Know Computer numerically controlled (CNC) Core engine

INTRODUCTION The engine repair and rebuilding industry has changed significantly in the past decade. This chapter was designed to give you a brief introduction to the current industry and the changes that have been made to machining equipment, repair facilities, and the daily operations. In the past, engines and vehicles were not built to the high standards they are now. If an engine and vehicle drove past 100,000 miles without a major repair, you were considered lucky and running on borrowed time. Today, consumers expect their engines and vehicles to give them reliable service for many more miles and years. The engines in the past were not built to today’s high standards and repairs such as valve jobs and rebuilds were common. Today, things have changed significantly. There are very few shops that will rebuild an engine in-house. When you are employed in the field, one of your jobs may be to help the customers choose what option is best for them. The information in this book, your experiences, and the shop you work in will all help you inform the customer as to what action should be taken. If repairing and rebuilding engines is what you have chosen to do as your career, you will have to know what options you will have and what types of operations the particular places of employment may do.

FULL-SERVICE REPAIR FACILITIES There are a lot of full-service repair shops across the nation. The full-service repair shops include independently owned, franchised, and new and used dealership facilities. The majority of these shops are willing to work on anything that comes in the door. Full-service Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 2

repair shops will typically perform oil changes and other small repairs at a lower advertised cost to drive customers to their door. This technique is common and allows the customer to become aware of the amount and type of work that is performed there. It also allows the shop to inspect the vehicle and make the customer aware of any problems with the vehicle. Once the customer’s trust is earned, there is a good chance that they will come back for a different repair and become long-term customers. The average full-service repair facility will have several bays and hoists to work with, along with computer terminals to write repair orders and look up service information. Rebuilding an engine in this type of repair facility is not nearly as common as it once was. Many independent shops used to own their own machine equipment, such as valve grinding machines. Since today’s engines need rebuilding less often, those same machines collect more dust and the shop owner or manager has to consider whether it is worth still keeping those machines around (and paying to maintain them) or to sell them (Figure 2-1). The space that a machine takes up on a floor must be usable if a shop is to remain profitable and stay open. New shops often do not purchase engine machining equipment unless they plan on specializing in engine work. If a shop does specialize in engine work, they often have a relationship with many neighboring repair facilities that send engine work to them. When an extensive engine repair is determined to be the course of action, many shops will subcontract the job to a specialist. Today, most independent shops perform engine repairs instead of rebuilds. These repairs may include, but are not limited to, head gaskets, engine seals, timing belts and chains, and oil leaks. When a major engine repair is needed, they may often choose to either install a crate engine or component, or send the engine parts out to an engine machine shop to be machined and then put the engine back together at the independent shop. One example is if an engine were to overheat, blow a cylinder head gasket, and crack the cylinder head. If this were to happen, the full-service repair shop will estimate the costs of replacing the head versus sending it out to a machine shop for machining and head reassembly. The shop in turn will charge the customer for the sublet service. Depending on the vehicle and engine, it may be more cost-effective to purchase crate components, especially if it is a popular component where there is a lot of supply and the cost is low. Most shops now prefer to install remanufactured components and engines because the company they purchase from is mostly responsible for the warranty of their product. But their preferred installation choice may be limited by the customer choosing a lower cost alternative.

Figure 2-1 This valve machine has not been used for the last few years. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Repair and Rebuilding Industry

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Engine repair work at a full-service shop does not usually require a technician to obtain training beyond what this book provides, but some shops prefer to have the lead technician or a specialized technician perform the work. Sometimes this technician is chosen because of the technician’s interest, experience, background, or specialized training.

MACHINE SHOP AND ENGINE REBUILD FACILITIES One-third of the full-service shops surveyed in the past few years indicate that they still own engine machining equipment, but most of them are now planning on selling them. Machine shops and engine rebuild facilities have been around for a long time. They exist as part of another facility, independent, or connected to a parts supply store. Many high-performance facilities will also perform repairs and rebuilding of normal engines. Most of these repair facilities have not changed their type of business much over the years but have found themselves focusing on the changes in technology and how it affects their business model. Machine shops will take in either complete engine repair and rebuilding or component repairs and rebuilding. Most machine shops survive and exist because they have a relationship with the local surrounding independent shops, franchises, and dealers. These supporters will send work out to the machine shop. Often the vehicle will not be housed at the machine shop, but there are a few exceptions. Some of the most common repairs at a machine shop are cylinder head remanufacturing and repairs, cylinder block remanufacturing, repairs and resizing, piston pressing, and component assembly. The extent of these repairs will vary. Machine shops have a significant advantage over purchasing crate engines. Both shipping costs and local support are two things that machine shops offer to distinguish themselves from large nationwide rebuilders. Often, machine shops will come across a repair for an older, antique, or highperformance engine. Each of these cases is handled separately, and the shop foreman or manager usually talks directly with the customer. Some machine shops have started to accept more high-performance work because of the instability of other work. Machine shops used to rely on cylinder heads and internal components failing at high enough rates to keep them in business. Modern engines have lower failure rates that keep them from needing extensive service frequently. Machine shops usually have a very costly inventory of machines and equipment (Figure 2-2). These machines not only have a high initial purchase, but also must be periodically maintained, calibrated, cleaned, and updated. Computer numerically controlled (CNC) equipment is sometimes used in a machine shop (Figure 2-3). This type of equipment requires special training, as do many of the machines and equipment

A computer numerically controlled (CNC) machine uses special computer software to machine close tolerances.

Figure 2-2 This milling machine can be used to resurface cylinder heads, block decks, or flywheels. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 2

Figure 2-3 A CNC machine is one of the many pieces of expensive equipment at a machine shop.

Figure 2-4 Machinists need to be able to understand and apply math.

in a machine shop. A CNC machine can cut and mill engine components to a smaller tolerance (more accuracy) than most human-operated and controlled machines. This is desirable because the smaller tolerances usually mean less comebacks and a higher-quality product. Machine shop technicians are required to have a good working knowledge of engine components, precision measuring tools, math, and the ability to locate resources quickly (Figure 2-4). There are a few specialized schools across the United States that specialize in teaching automotive machining.

ENGINE REPAIR AND REPLACEMENT SPECIALTY FACILITIES Engine repair and replacement has almost become a separate industry in itself. In the past, the transmission repair and rebuilding industry had separated itself from the rest of the industry by having shops offer complete transmission work at one facility. Transmissions are very complicated and can require extensive testing and highly skilled technicians to work on them. The growing complexity of modern engines requires similarly skilled technicians and extensive testing. Today’s engines are designed with tighter clearances for more efficiency. Replacing or rebuilding the engine in a modern vehicle requires a higher level of knowledge and skill. Technicians must also be able to transfer that knowledge over to a different vehicle and a different setup. The facility must be well-equipped if a profit is to be made. The amount and cost of the equipment and technician training are significant factors to consider when offering engine rebuilding and repair at a facility. It is for these reasons that specialized shops exist. These shops offer engine and related work. They can usually diagnose and repair the cause in-house, saving money for the customer and keeping the profit in one place. Sometimes, a component replacement is all that is needed. Specialized shops rely on a good source of parts and equipment to operate. If cost is a strong customer consideration, then installing a good, used engine may be an option to consider with the customer. Some of the specialized shops offer and advertise high-performance and restoration work. This may account for a significant amount of their business in some cases. Specialized shops may also perform custom machining, cylinder porting, and engine tuning. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Repair and Rebuilding Industry

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ENGINE AND COMPONENT REMANUFACTURING FACILITIES As mentioned earlier, today’s engines are lasting longer, and repairs are less frequent. Because the bodies and other mechanical components do not rust and wear out as frequently either, many consumers are repairing their high-mileage engines that need replacement, because it costs less than purchasing another vehicle. For many years, manufacturers have been placing the same engine in several models. For example, the Chevrolet 5.7 L (350 cubic inch displacement) engine was used in many light truck and car applications for decades. Many of the components are interchangeable from one to the next. Because of the volume and number of components out there, the cost of the parts and crate components (and engines) is significantly lower than many other engine families. This is because of the volume of parts and components produced for this engine. Many manufacturers beside General Motors have adapted this strategy. Many domestic vehicles are being built on a “global” platform. An example of engine production in volume is the Global Engine Manufacturing Alliance LLC (GEMA) World Engine, which until 2012 had a joint venture with Chrysler. The World Engine had five factories worldwide and produced about 2 million engines per year. Approximately 20 different vehicles by Chrysler, Mitsubishi, Hyundai, and Fiat used the 1.8 L, 2.0 L, and 2.4 L World Engines, each slightly different for its own application. The World Engine was used in vehicles all over the globe. With more manufacturers producing similar products, another segment of engine rebuilding and remanufacturing was created because of the volume. There are only a few engine and component remanufacturing facilities in the United States. Their products can be purchased directly from them, a parts store, or an authorized dealer/installer. These facilities are large and have the capability of “assembly line production style” engine remanufacturing because of their volume. Remanufacturing starts out with a core engine. The core engine is an old, used, or discarded engine that was received from a variety of sources. These sources include salvage yards and a customer’s old engine that was returned. A core charge is usually placed on a new engine when it is ordered. This is an extra charge that the customer (or repair facility) must pay until the old engine that was removed is sent back in the same shipping crate. The old engine is then inventoried and completely stripped down to the bare components. The major components, such as the cylinder head, block, and crankshaft, are checked for cracks (Figure 2-5) and are machined, repaired, or discarded as needed. They are then

A core engine is a used engine that is disassembled for purposes of rebuilding in large volumes.

Figure 2-5 Machine shops and engine remanufacturing plants usually have expensive equipment. This crankshaft is being inspected for cracks using a magnet. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 2

inventoried and stored for later use. The major components are then thoroughly cleaned and ready for reassembly. These engine components are also often sold as individual remanufactured components. During reassembly, new parts are installed, and everything is measured, tested, and torqued to specification. The engines are then started and tested to ensure that the customer receives a high-quality product. Some of the main advantages of purchasing an engine from a remanufacturer are the warranty, quality control, and lower cost.

SUMMARY ■

■ ■

Automotive and light truck engines last longer today than they did in the past. This has led to changes in the engine repair and rebuilding industry. Machine shops perform the majority of engine machining and repairs today. A CNC machine uses special computer software to machine close tolerances.

■ ■ ■

Specialized shops sometimes offer highperformance engine work. Engine remanufacturing in large volumes helps lower the price. A core engine is a used engine that is disassembled for purposes of rebuilding in large volumes.

REVIEW QUESTIONS Short-Answer Essays

Fill-in-the-Blanks

1. Describe why an engine remanufacturer receives core engines.

1. A new car dealership is considered a _______________ service repair facility.

2. Describe what a CNC machine is.

2. Technicians who work at a machine shop have to use _______________ measuring tools as part of their daily job.

3. Explain why full-service repair shops perform more engine repairs and component replacements than engine rebuilding. 4. Mention where engine remanufacturers receive their core engines from. 5. Describe the relationship between a full-service repair facility and a machine shop. 6. Explain why engine repair and rebuilding specialty shops exist. 7. Describe the type of repairs an engine repair and rebuilding specialty shop may perform. 8. List where you can purchase a remanufactured engine. 9. Explain why a shop sometimes prefers to install a remanufactured engine or component instead of rebuilding. 10. List the advantages and disadvantages of a fullservice repair facility owning engine machining equipment.

3. When an installer purchases a remanufactured engine, a _______________ _______________ must be paid until the old engine is returned. 4. A CNC is a_______________ _______________ _______________ machine. 5. Engine remanufacturing in large volumes helps lower the _______________. 6. Rebuilding a modern engine requires a _______________ technician due to their growing complexity. 7. A machine shop’s inventory or machines and equipment cost is usually very _______________. 8. High-performance and restoration engine work is usually performed at a _______________ repair facility. 9. A crate remanufactured engine offers a _______________ with its purchase.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Repair and Rebuilding Industry

10. Modern engines have _______________ failure rates that keep them from needing extensive service frequently.

Multiple Choice 1. Where would you typically find an “assembly line” for engine rebuilding? A. Specialty shop B. Full-service shop C. New car dealership D. Remanufacturing facility 2. The World Engine can be found in what vehicles? A. Chrysler C. Chevrolet B. Ford D. Both B and C 3. Specialized engine rebuilding shops usually work on: A. high-performance engines. B. restoration engines. C. race engines. D. all of the above. 4. Technician A says that a remanufactured engine that comes from an engine remanufacture facility typically has a warranty. Technician B says that an engine remanufacture facility will charge you a core charge if you do not send the old engine back to them. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. Technician A says that a machine shop’s inventory is high compared to other automotive repair shops. Technician B says that there are very few machines at new car dealerships. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

21

6. Technician A says that a CNC machine can cut and mill engine components. Technician B says that a CNC machine is computer controlled. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. Technician A says that a CNC machine can mill an engine part with more accuracy than a regular machine. Technician B says that using a CNC will usually result in more customer comebacks. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that a remanufacturing facility may receive its core engines from salvage yards. Technician B says that a remanufacturing facility may receive its core engines from customers who purchased engines from them. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. The failure rate on a modern engine is A. lower than an older engine. B. higher than an older engine. C. similar to that of an older engine. D. none of the above. 10. Technician A says that an engine-rebuilding technician at a machine shop must be able to make precision measurements. Technician B says that not much math is involved when you are working as an engine rebuilding technician at a machine shop. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 3

THEORY OF ENGINE OPERATION

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■

■ ■ ■ ■

Major engine components. Basic engine operation. Basic laws of physics involved with engine operation. Engine classifications according to the number of cycles, the number of cylinders, cylinder arrangement, and valvetrain type. The four-stroke cycle theory. The different cylinder arrangements and the advantages of each. The different valvetrains used in modern engines. Engine measurement terms such as bore and stroke, displacement,

■ ■

■

■

compression ratio, engine efficiency, horsepower and torque, horsepower losses, mechanical efficiency, and thermal efficiency. The relationship between compression ratio and engine power output. Mechanical, volumetric, and thermal efficiencies, and factors that affect each. The basic operation of alternative engine designs, including two-stroke, diesel, and stratified charge. The internal components of a diesel engine and how they differ from those of a gas engine.

Terms To Know Autoignition temperature Bore Bottom dead center (BDC) Boyle’s law Brake horsepower Coil Compression-ignition (CI) engines Compression ratio Connecting rods Crankshaft Cycle Detonation Displacement Dual overhead cam (DOHC) Engine Efficiency 22

Engine bearings Friction Fuel injection Glow plugs Gross horsepower Horsepower Hybrid electric vehicle (HEV) Indicated horsepower Internal combustion engine Kinetic energy Law of conservation of energy Mechanical efficiency Net horsepower Overhead cam (OHC) Overhead valve (OHV) Piston rings

Potential energy Preignition Reciprocating Reed valve Rotary valve Spark-ignition (SI) engine Stroke Thermal efficiency Thermodynamics Top dead center (TDC) Torque Transmission Transverse-mounted engine Vacuum Valve overlap Volumetric efficiency (VE) Wrist pin

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

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INTRODUCTION Today’s engines are designed to meet the demands of the automobile-buying public and many government-mandated emissions and fuel economy regulations. High performance, fuel economy, reduced emissions, low noise level, smooth operation, and reliability are demanded from consumers. To fulfill these consumer needs, manufacturers are producing engines using lightweight blocks and cylinder heads, and nontraditional materials such as powdered metals and composites. In the past, engines were made from heavier and lowercost raw materials such as iron and steel. While many of the engine’s mechanical components are similar to those of over 100 years ago, refinements in design, materials, and machining help the manufacturers improve engine performance and reliability. Many engine and support system functions are now closely controlled by the powertrain control module (PCM). Fuel delivery, spark timing, and often valve timing are managed so precisely that the PCM can make adjustments within milliseconds; a millisecond is one-thousandth of a second. Today’s technician is called upon to diagnose and service these advanced engines properly. The internal combustion engine used in automotive applications uses several laws of physics and chemistry to operate. Although engine sizes, designs, and construction vary greatly, they all operate on the same basic principles. This chapter discusses these basic principles and engine designs.

MAJOR ENGINE COMPONENTS The engine’s cylinder block is the structure that the rest of the engine is built upon (Figure 3-1). The block has precisely machined holes, known as cylinder bores, in which the pistons are moved up and down. The number of cylinder bores describes the engine: a three-, four-, five-, six-, eight-, ten-, or twelve-cylinder engine. These bores are typically between 2.5 and 4.25 inches (6.35 and 10.795 cm) on common production vehicles and light duty trucks. Lengthwise across the bottom of the block is another bore that supports the crankshaft. The downward linear movement of the pistons rotates the crankshaft. The pistons are connected to the crankshaft by the connecting rods.

Internal combustion engines burn their fuels within the engine.

A crankshaft is a shaft held in the engine block that converts the linear and reciprocating motion of the pistons into a nonreversing rotary motion used to turn the transmission. The crankshaft rotates in only one direction. It is not reversible.

The connecting rod forms a link between the piston and the crankshaft.

Figure 3-1 This engine block is an eight cylinder. It is a V-style engine with four cylinders on each bank of the V. This photo shows four cylinders on one bank of the V. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3

Figure 3-2 This engine cutaway shows the major components of the engine.

The crankshaft connects to the transmission and provides the rotary motion to turn the wheels. In many cases the transmission rotates in the same direction as the engine, except when it is in the reverse gear. On top of the block covering the cylinders is the cylinder head. It houses valves that open and close to allow fresh air and fuel into the cylinders and burnt exhaust gases out. Look at Figure 3-2 to identify these components in the engine. The cylinder block also has oil and coolant passages drilled throughout it to circulate these vital fluids to key areas in the block and the cylinder head. The water and oil pumps are mounted directly to the block in several different ways. Sometimes these components are internal and behind a cover. In other cases they are external and visible without removing any components. Both the water and oil pumps are moving objects. They are usually driven by the movement of the crankshaft via a belt, gear, or chair, but they are sometimes electrically driven. The crankshaft is a long iron or steel fabrication with round bearing surfaces machined onto it called journals (Figure 3-3). The crankshaft must be made to be very strong. The

Figure 3-3 A crankshaft for an eight-cylinder engine. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

main journals form the centerline of the crankshaft. Main engine bearings fit into the main bores of the engine block, and the crankshaft can spin freely in this mounting. There is just enough clearance (or space) between the bearings and the journals to allow a thin film of pressurized oil to keep the journals from actually riding on the bearings. Half of the main bore is integral to the block. Main caps form the other half of the bore; these can be removed to service the crankshaft, bearings, pistons, and other components. The crankshaft also has journals that are offset from the centerline. These are called rod journals because the connecting rods, fitted with rod bearings, bolt around these journals to attach to the crankshaft. The rod bearings are very similar to the main bearings. When the piston pushes the connecting rod down on the offset journal of the crankshaft, it forces the crankshaft to rotate. The continued motion of the crankshaft in the same direction is caused by the piston moving in the opposite direction (in the cylinder bore). The crankshaft also has counterweights or crankshaft throws that are offset around the shaft. The weight of these throws helps offset the crankshaft speed fluctuations and vibrations as the different cylinders produce power. The pistons are slightly smaller than the cylinders, to allow them to move up and down with minimal friction. They are fitted with piston rings that seal the area between the piston and the cylinder wall. The piston connects to the small end of the connecting rod through a wrist pin (sometimes called a piston or gudgeon pin) and a bushing. The force of combustion (which is the explosion of fuel and air) on the top of the piston forces it to move with power. It is transferred to the crankshaft through the connecting rod. As the piston moves up and down in the cylinder, it rotates the crankshaft. This process converts the reciprocating motion of the piston into rotary motion (Figure 3-4). This rotary motion is what is needed to turn the tires and wheels after the energy is transferred through the transmission and differential. A flywheel or flexplate at the rear of

Engine bearings are two bearing halves that form a circle to fit around the crankshaft journals. Piston rings are hard cut rings that fit around the piston to form a seal between the piston and the cylinder wall. A wrist pin is a hardened steel pin that connects the piston to the connecting rod and allows the rod to rock back and forth as it travels with the crankshaft. The transmission is a device that uses the rotary motion and power of the crankshaft to turn the differential and driveshafts. The transmission multiplies the power output and changes the speed of the driveshaft using different gear ratios.

Cylinder head

Valve

Valve Piston rings

Combustion

Piston

Piston pin

Cylinder Up and Down motion

25

Connecting rod

Thrust (Rotary motion)

Crankshaft

Figure 3-4 The engine components at work. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3

the crankshaft, along with a balancer pulley at the front, provides a large, stable mass for smoothing out the rotation and dampening the pulsations of the power stroke. Automatic transmissions use flexplates, and manual transmissions use flywheels. The cylinder head forms a tight cover for the top of the cylinders and contains machined chambers into which the air-fuel mixture is forced and ignited (Figure 3-5). The void area of the cylinder head located above the cylinder bore is called the combustion chamber. It is sealed on the top by the cylinder head and valves and on the bottom by the pistons and rings. The cylinder head also has threaded holes for the spark plugs that screw right into the head so their tips protrude into the combustion chambers. Some cylinder heads have threaded holes for fuel injectors (such as diesel and gasoline direct injection engines). The valves in each cylinder are opened and closed by the action of the camshaft and related valvetrain. The camshaft is connected to the crankshaft by a gear, chain, or belt and is reduced to drive at one-half of the crankshaft’s speed. In other words, for every complete revolution the crankshaft makes, the camshaft makes one-half of a revolution. This makes the speed of the crankshaft exactly half of the crankshaft. The camshaft may be mounted in the engine block itself or in the cylinder head, depending on design. Some engines use two camshafts in the head; these are called dual overhead cam engines. The camshaft has lobes that are used to open the valves (Figure 3-6). A camshaft mounted in the block operates the valves remotely through pushrods and rocker arms; others act on followers placed directly on top of the valves. In some overhead camshaft (OHC) engines, the camshaft lobes contact the rocker arms that may be mounted on a rocker arm shaft. Lubricating oil for the engine is normally stored in the oil pan (sometimes called a sump) mounted to the bottom of the engine. The oil is force-fed under pressure to almost all parts of the engine by the oil pump.

Journals

Lobes

Figure 3-6 A camshaft.

Figure 3-5 The cylinder head and valves seal the top of the combustion chamber. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

27

ENGINE OPERATING PRINCIPLES One of the many laws of physics used within the automotive engine is thermodynamics. The driving force of the engine is the expansion of gases. Gasoline (a liquid fuel) will change its state to a gas if it is heated or burned. Gasoline must be mixed with oxygen before it can burn. In addition, the air-fuel mixture must be burned in a confined area to produce power. Gasoline that is burned in an open container produces very little power, but if the same amount of fuel is burned in a closed container, it will expand producing usable force. When the air-fuel mixture changes states, it also expands as the gas molecules collide with each other and bounce apart. Increasing the temperature of the gasoline molecules increases their speed of travel, causing more collisions and expansion. Heat is generated by compressing the air-fuel mixture within the combustion chamber. Igniting the compressed mixture causes the heat, pressure, and expansion to multiply. This process releases the energy of the gasoline so it can produce work. The igniting of the mixture is more of a controlled burn, rather than an explosion. The controlled combustion releases the fuel energy at a controlled rate in the form of heat energy. The heat, and consequential expansion of molecules, dramatically increases the pressure inside the combustion chamber. Typically, the pressure works on top of a piston that is connected to the connecting rod and crankshaft. The expanding gases push the piston down with tremendous force and speed. As the piston is forced down, it causes the crankshaft to rotate. This rotation is a twisting force. This twisting force on the crankshaft is called torque. Torque is applied to the drive wheels through the transmission and differential. As the engine drives the wheels to move the vehicle, a certain amount of work is done. The rate of work being performed in a certain amount of time is measured in horsepower.

Thermodynamics is the study of the relationship and efficiency between heat energy and mechanical energy.

Torque is a rotating force around a pivot point. Horsepower is a measure of the rate of work.

Energy and Work In engineering terms, in order to have work, there must be motion. Using this definition, work can be measured by combining distance and weight and is expressed as foot-pound (ft.-lb.) or newton meter (Nm). These terms describe how much weight can be moved a certain distance. A foot-pound is the amount of energy required to lift and move 1-pound of weight 1 foot in distance. The amount of work required to move a 500-pound weight 5 feet is 2,500 foot-pounds (3,390 Nm). In the metric system, the unit used to measure force is called a newton meter (Nm). A Newton is a unit measure of force, similar to a pound. Torque is measured as the amount of force in Newtons multiplied by the distance that the force acts in meters. One foot-pound is equal to 1.355 Nm. It is important to understand both systems because manufacturers will use both systems. Energy produces work that can be measured in units, such as torque. Basically, energy is anything that is capable of resulting in motion. Common forms of energy include electrical, chemical, heat, radiant, mechanical, and thermal. The law of conservation of energy states that the total amount of energy in an isolated system remains constant. Energy cannot be created nor destroyed; however, it can be stored, controlled, and changed into other forms of energy. For example, the vehicle’s battery stores chemical energy that is changed into electrical energy when a load is applied. An automotive engine converts thermal (heat) energy into mechanical energy or power to produce force and motion. During combustion, when the gasoline burns, thermal energy is released. The engine converts this thermal energy into mechanical energy. Mechanical energy provides movement. The heat, expansion, and pressure during combustion all supply thermal energy within the combustion chamber. This thermal energy is converted to mechanical energy as the piston is pushed downward in the cylinder with great force. Often the engine under the hood is referred to as a motor. In automotive

The law of conservation of energy is a principal law of physics that states that the total energy of an isolated system remains constant despite any internal changes. An engine is defined as a device or machine that converts thermal energy into mechanical energy.

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terms, a motor is referred to as a driving and moving device that is electrically or vacuum controlled.

Types of Energy Potential energy is energy that is not being used at a given time, but which can be used. Kinetic energy is the amount of energy that is currently being used or is currently working.

There are two types of energy: potential and kinetic. Potential energy is available to be used but is not being used. An example of this in the automobile is the chemical energy of the battery when the engine and ignition are turned off. Most of the chemical energy is stored as potential energy. (A very small percentage of the available energy is actually being used to keep computer memories alive.) When the ignition key is turned to start and the starter begins to crank the engine over, kinetic energy is being used. Kinetic energy is energy that is being used or working. The battery is now providing significant chemical energy to the starter so it can do work.

Energy Conversion In our example of the battery starting the engine, several energy conversions occur. Energy cannot be destroyed or eliminated, but it can be converted from one state or form to another. The starter converts the chemical energy from the battery into electrical energy to engage the starter. The starter converts this electrical energy into mechanical energy to crank the engine over. At the same time, chemical energy from the battery is being converted to electrical energy to provide power to the fuel, ignition, and computercontrolled systems so they will have the needed fuel and spark to start and run the engine. When combustion is in a rapid enough sequence, the starter is disengaged and the engine is kept running without the starter’s assistance. The speed of the engine when it is running and idling is faster than its speed when it is starting. Combustion uses the potential energy in gasoline and converts it into kinetic energy by burning it. The chemical energy of the fuel is converted to thermal energy by the heat produced during combustion. The thermal energy is converted to mechanical energy by the movement of the pistons and the crankshaft. The following energy conversions are all common automotive applications: Chemical Energy Conversion to Thermal Energy. As fuel is burned in the combustion chambers, the chemical energy in the fuel is converted to thermal energy. Thermal Energy Conversion to Mechanical Energy. As the heat, pressure, and expansion of gases develop during combustion, thermal energy increases. This thermal energy is converted to mechanical energy to drive the vehicle through energy exerted on top of the pistons, which turns the crankshaft to drive the transmission and drive wheels. Chemical Energy Conversion to Electrical Energy. The battery stores chemical energy and converts it to electrical energy as electrical loads such as the starter, the powertrain control module, the fuel injectors, and the radio demand electricity.

A hybrid electric vehicle (HEV) uses an electric motor in combination with a gas, diesel, or alternate fuel engine to power the vehicle.

Electrical Energy Conversion to Mechanical Energy. The starter, fuel injectors, electric cooling fan, and windshield wiper motor are just a few of the many automotive applications of conversion of electrical energy into mechanical motion. A hybrid electric vehicle (HEV) uses electricity to power an electric motor, which then turns the transmission with or without the engine running. Mechanical Energy Conversion to Electrical Energy. The generator provides electrical energy to recharge the battery by using the mechanical energy of rotation through a belt connected to the rotating crankshaft. HEVs use regenerative braking during deceleration to recharge the high-voltage battery pack. Mechanical Energy Conversion to Thermal Energy. The braking system on a traditional internal combustion engine vehicle is a fine example of this form of energy conversion. The mechanical energy of the rotating wheels is changed into thermal energy

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Theory of Engine Operation

through the friction created between the rotating brake discs or drums and the stationary friction surfaces of the brake pads or shoes. The thermal energy is dissipated to the atmosphere.

Newton’s Laws of Motion First Law. A body in motion tends to stay in motion. A body at rest tends to stay at rest. Forces applied to the body at rest can overcome this tendency and make it move. Examples of some of the opposition forces that act on a body in motion are gravity and friction. Certainly the crankshaft, transmission, and drive wheels will not propel the car forward from a rest position unless significant force is applied to the pistons to rotate the crankshaft and overcome the opposition forces.

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Friction is resistance to motion when one object moves across another object. Friction generates heat and is an excellent method of controlling mechanical action.

Second Law. A body’s acceleration is directly proportional to the force applied to it. The greater the force applied to the drive wheels, the greater the acceleration of the vehicle. The greater the friction on a braking system, the greater the deceleration of the vehicle. Third Law. For every action, there is an equal and opposite reaction. A simple application of this law on the automobile involves the suspension system. When the tire travels over a bump, the wheel moves upward with a force that opposes the spring’s tension. When the wheel passes the bump, the spring exerts its opposite reaction to force the wheel back down toward the road and return it to its original position.

Inertia Inertia is the tendency of an object at rest (static inertia) to stay at rest or an object in motion (dynamic inertia) to stay in motion. The heavy flywheel attached to the end of the crankshaft on manual transmission vehicles uses the inertia of the rotating crankshaft to help it continue to spin smoothly between the combustion events in the cylinders. The engine would not run as smooth if it had a lighter weight flywheel.

Momentum Momentum is when force overcomes static inertia and causes movement of an object. As the object moves, it gains momentum. Momentum is calculated by multiplying the object’s weight times its speed. An opposing force will reduce momentum. The larger the mass of an object, the more momentum it will have. A large truck has more momentum than a small car.

Friction In the engine, the piston rings generate friction against the cylinder walls. Friction opposes momentum and mechanical energy. Friction creates heat and reduces the mechanical energy of the piston as it is pushed downward to turn the crankshaft. This is an example of how part of an engine’s efficiency is decreased. Friction may occur in solids, liquids, and gases. The airflow over a vehicle causes friction. The manufacturers carefully engineer their vehicles to be aerodynamic. This means that the resistance to motion from friction between the vehicle and the air is minimized. This is carefully calculated and measured as the coefficient of drag (Cd). Unfortunately, there are certain external conditions and factors that can cause a vehicle to lose up to half of its mechanical energy. Examples of some of these factors are aerodynamic drag, excessive rolling resistance, and the environment the vehicle drives in. Manufacturers spend a lot of time and focus on trying to reduce a vehicle’s coefficient of drag so that the engine does not have to produce much power to keep it moving on the road. This will help a vehicle get better fuel mileage.

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BEHAVIOR OF LIQUIDS AND GASES Molecular Energy Electrons are in constant motion around the nucleus of atoms or molecules. Kinetic energy is always occurring. The kinetic energy of liquids, gases, and solids changes in response to temperature. When temperature decreases, so does kinetic energy. As temperature increases, so does kinetic energy. Solids have the slowest reaction to temperature, while gases have the quickest response to changes in temperature. We know this theory already through our discussion of combustion. As temperature increases within the combustion chamber, the gases rapidly expand and the increasing kinetic energy is used to create thermal energy that is converted into mechanical energy.

Temperature The volume of liquids, gases, and solids increases with temperature. It is the increased volume of gases on top of the pistons that produces the force to push the piston downward. When filling engine fluids, such as tire air pressure and coolant, we must be aware of the effects of temperature on volume. It is easy to overfill a coolant reservoir if the coolant is at ambient temperature and you top the fluid off to the maximum level. As the fluid heats up, it may expand beyond the capacity of the reservoir and develop enough pressure to blow the cap’s pressure relief valve. The same is true for checking air pressure in a tire. After driving for some time, the friction of the tires will raise the temperature of the tires and then raise the temperature of the air inside the tires. This results in raising the pressure inside the tires. Manufacturers suggest that you check and adjust tire pressure when it is cold or be aware of the difference that may occur when doing it at higher temperatures.

Pressure and Compressibility Pressure is always applied equally to all surfaces of a closed container. If there is a leak in the container, the pressure will leak out and equalize with the pressure that is outside the container. Gases and liquids both flow, so they are classified as fluids. But there are distinct and significant differences between the characteristics of gases and liquids. Gases can be compressed; the molecules squeeze tighter together and form greater pressure. You can easily fill a tire with excess pressure. Further compression of the gases in a combustion chamber will produce more power. Liquids, on the other hand, are difficult to compress. A liquid fills a chamber, and you cannot add more liquid; you can only increase pressure. Brake and clutch hydraulic systems work with liquids. When you depress the clutch or brake pedals, you move the liquid, under pressure, to exert force on a piston. This force produces mechanical work from the brake caliper piston or the clutch hydraulic lever. If there is a leak in the system, air can enter. Air is a gas and is compressible. Air in a hydraulic system will cause a lack of pressure and force.

PRESSURE AND VACUUM Air is a gas with weight and mass. It is layered high above the surface of the earth and exerts a pressure on the earth’s surface. This pressure is called atmospheric pressure. A 1-square-inch column of air extending from the earth’s surface at sea level to the outer edge of the earth’s atmosphere weighs 14.7 pounds. We say that atmospheric pressure is 14.7 pounds per square inch at sea level. This pressure changes as we climb in altitude. If we are 14,000 feet above sea level in the mountains, that column of air no longer weighs 14.7 pounds because the distance to the edge of the earth’s outer atmosphere is less; Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

atmospheric pressure therefore decreases. Also, as temperature decreases, the molecules become less dense and therefore weigh less; atmospheric pressure decreases. These changes in atmospheric pressure caused by altitude and temperature are important for the PCM to know about to deliver the correct amount of fuel for the actual amount of air in the cylinder. When air pressure is greater than atmospheric pressure, it is a positive pressure. When air pressure is lower than atmospheric pressure, it is a negative pressure, or vacuum. The engine creates a vacuum when the intake valves are open and the pistons move from the top of the cylinder to the bottom As the pistons reaches BDC the difference in pressure between the low pressure area created above the piston in the cylinder and the outside air cause a rush of air until the pressure has equalized Vacuum is typically not measured in pounds per square inch. It is typically measured in inches of mercury vacuum (in. Hg) or bar. When working on a vehicle, you will use a vacuum/pressure gauge. At atmospheric pressure, a vacuum gauge will read 0 in. Hg. It will also read 1 bar, 14.7 psi atmospheric, or 0 psi gauge. When there is a total absence of air or 0 absolute pressure (no atmospheric pressure at all), a perfect vacuum exists. It is measured at 29.9 in. Hg vacuum, 0 bar, or 0 psi atmospheric. An engine develops significant vacuum during its intake stroke as the pistons move downward and the valves begin to close. Liquids, solids, and gases move from an area of high pressure to an area of low pressure because of the force caused by the state of vacuum. Automotive engines rely on engine vacuum and this principle to fill the combustion chambers with air to support combustion. When the throttle is opened, atmospheric pressure flows rapidly into the low pressure area of the cylinder to fill it with air. An engine that cannot develop adequate vacuum will not pull in enough air to make maximum power. A modern, good-running engine will typically develop about 16–18 in. Hg vacuum at idle. It is important to understand that a vacuum does not mean that air is sucked into the space with a lower pressure. When a vacuum is created, air is forced from the area of higher pressure (typically atmospheric pressure outside of the engine and near the intake) to the area of lower pressure (typically the combustion chambers). Vacuum is also dependent on volume and temperature. Turbocharged and supercharged engines increase this pressure difference before or after the throttle plate to help fill the combustion chambers fully under all conditions.

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A vacuum is a space in which the pressure is significantly lower than the pressure around it. In an engine, we define this as the pressure inside the engine being less than atmospheric and therefore a vacuum exists. Vacuum is considered a force and can move fluids from their rest position.

BOYLE’S LAW Boyle’s law states that if the temperature remains constant, the volume of a given mass of gas is inversely proportional to the absolute pressure. Boyle’s law is a summary of the relationships between pressure, temperature, and volume. The fuel and air mixture enters the combustion chamber because of a vacuum. The combustion chamber still has pressure, but it is less than atmospheric pressure. This lower pressure is a direct result of the increasing volume in the combustion chamber.

ENGINE OPERATION Most automotive and truck engines are four-stroke cycle engines. A stroke is the movement of the piston from one end of its travel to the other; for example, if the piston is at the top of its travel and then is moved to the bottom of its travel, one stroke has occurred. Another stroke occurs when the piston is moved from the bottom of its travel to the top again. A cycle is a sequence that is repeated. In the four-stroke engine, four strokes are required to complete one power-producing cycle.

The stroke is the amount of piston travel from TDC to BDC measured in inches or millimeters. A cycle is a complete sequence of events.

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Top dead center (TDC) is a term used to indicate that the piston is at the very top of its stroke. Bottom dead center (BDC) is a term used to indicate that the piston is at the very bottom of its stroke.

The autoignition temperature is the minimum temperature required to ignite a gas in air without a spark or flame to assist.

Valve overlap is the length of time, measured in degrees of crankshaft revolution, that the intake and exhaust valves of the same combustion chamber are open simultaneously. In some engines, valve timing and overlap are variable. Reciprocating is an up-and-down or back-and-forth repetitive motion.

The internal combustion engine must draw in an air-fuel mixture, compress the mixture, ignite the mixture, and then expel the exhaust. This is accomplished in fourpiston strokes (Figure 3-7). Diesel and gasoline direct injection engines draw only air into the combustion chamber; fuel is then injected directly into the combustion chamber and mixed. The first stroke of the cycle is the intake stroke (see Figure 3-7A). As the piston moves down from top dead center (TDC), the intake valve is opened so the vaporized air-fuel mixture can be pushed into the cylinder by atmospheric pressure. As the piston moves downward in its stroke, a vacuum is created (low pressure). Since high-pressure air is forced to move toward low pressure, the air-fuel mixture is pushed past the open intake valve and into the cylinder. After the piston reaches bottom dead center (BDC), the intake valve is closed, and the stroke is completed. Closing the intake valve after BDC allows an additional amount of air-fuel mixture to enter the cylinder. Even though the piston is at the end of its stroke and no more vacuum is created, the additional mixture enters the cylinder because it weighs more than air alone. The momentum of air flowing into the cylinder also helps pull more air in after the piston has reached BDC. The compression stroke begins as the piston starts its travel back to TDC (see Figure  3-7B). The intake and exhaust valves are both closed, trapping the air-fuel mixture in the combustion chamber. The movement of the piston toward TDC compresses the mixture. When the piston reaches TDC, the mixture is fully compressed and is highly combustible because the mixture is close to its autoignition temperature. The ignition system induces a spark at exactly the right time to produce maximum power The actual timing of the spark on a modern engine is controlled by the PCM (powertrain control module), also referred to as ECM (engine control module) by some manufacturers, and it varies based on temperature, speed, fuel content, load, and other operating factors. This ensures that peak pressure will act on the piston when it is just headed downward and before the volume of the chamber has increased significantly. When the spark occurs in the compressed mixture, the rapid burning causes the molecules to expand, beginning the power stroke (see Figure 3-7C). The expanding molecules create a pressure above the piston and push it downward. The downward movement of the piston in this stroke is the only time the engine is productive concerning power output. During the power stroke, the intake and exhaust valves remain closed. Just prior to the piston reaching BDC, the exhaust valve is opened and the exhaust stroke of the cycle begins (see Figure 3-7D). The upward movement of the piston back toward TDC pushes out the exhaust gases from the cylinder past the exhaust valve and into the vehicle’s exhaust system. As the piston approaches TDC, the intake valve opens and the exhaust valve is closed a few degrees after TDC. The degrees of crankshaft rotation when both the intake and exhaust valves are open are called valve overlap. Valve overlap uses the movement and momentum of air to help fully clean out the spent gases and fill the chamber with a fresh charge of air and fuel. The cycle is then repeated again as the piston begins the intake stroke. This cycle is occurring simultaneously in the other cylinders of the engine, though the individual strokes do not occur at the same time. For example, cylinder number one will produce its power stroke; then while its exhaust stroke occurs, cylinder number three will be on its power stroke. This keeps rotating the crankshaft around with regular impulses. Most engines in use today are referred to as reciprocating. Power is produced by the up-and-down movement of the piston in the cylinder. This linear motion is then converted to rotary motion by a crankshaft.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation Intake valve closing

Both valves closed

Air/fuel mixture

A

Ignition

B Compression stroke 51°BTDC

Compression stroke 20°BTDC

Both valves closed

C

Exhaust valve opening

D Power stroke

Power stroke 57°BBDC

Figure 3-7 The four strokes of an automotive engine: (A) intake stroke, (B) compression stroke, (C) power stroke, (D) exhaust stroke.

A BIT OF HISTORY License plates made their first appearance on vehicles in the United States in 1901. In 1905, California began licensing and registering motor vehicles. By the end of 1905, California had registered 17,015 vehicles. Owners had to conspicuously display the circular or octagonal tags in the vehicle. To register the vehicle, it had to have working lamps, satisfactory brakes, and a bell or a horn.

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ENGINE CLASSIFICATIONS Engine classification is usually based on the number of cycles, the number of cylinders, cylinder arrangement, and valvetrain type. Additional descriptors include the location and number of camshafts and the type of fuel and ignition systems. Engine displacement is commonly used to identify engine size. Sometimes different methods may be used to identify the same engine. For example, a Chrysler 2.0-liter DOHC is also identified as a 420A and D4FE. In this case, the engine has a displacement of 2.0 liters and uses dual overhead camshafts. The 420A is derived from four valves per cylinder, has 2.0 liters displacement, and is American built. The D4FE means the engine uses dual overhead camshafts with four valves per cylinder and has front exhaust (the exhaust manifold is mounted facing the front of the vehicle). This section will define many of the terms used by automotive manufacturers to classify their engines.

Number of Cylinders One cylinder would not be able to produce sufficient power to meet the demands of today’s vehicles. Most automotive and truck engines use three, four, five, six, eight, ten, or twelve cylinders. The number of cylinders used by the manufacturer is determined by the amount of work required from the engine. Generally, the greater the number of cylinders, the more power the engine can produce. Also, the more cylinders, the greater number of power pulses in one complete 720-degree cycle. This produces a smoother running engine because the vibration of power stroke pulses cancel out each other. Many Jaguars have V12 engines not just because they are powerful but because they are inherently smooth. Vehicle manufacturers attempt to achieve a balance among power, economy, weight, and operating characteristics. An engine having more cylinders generally runs and idles more smoothly than those having three or four cylinders. This is because there is less crankshaft rotation between power strokes. There is less time between the combustion chamber explosions that cause the sudden acceleration of the piston, which is the source of vibrations. However, adding more cylinders to the engine design usually increases the weight of the assembly, the complexity of the design, and the cost of production. Over the years, manufacturers have changed their cylinder number, size, and arrangement designs to meet the ever-changing consumer demands, fuel mileage, and emissions laws.

Cylinder Arrangement Engines are also classified by the arrangement of the cylinders. The cylinder arrangement used is determined by vehicle design and purpose. The most common engine designs are in-line and V-type. The in-line engine places all of its cylinders in a single row (Figure 3-8). Advantages of this engine design include ease of manufacturing and serviceability. The disadvantage

4 cylinder 6 cylinder

Figure 3-8 In-line engines are designed for ease of construction and service. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

of this engine design is the block height. This causes higher hood lines on rear wheel drive vehicles resulting in less than optimum front aerodynamics. Many manufacturers overcome this disadvantage by installing a transverse-mounted engine in the engine compartment of front-wheel-drive vehicles. A modification of the in-line design is the slant cylinder (Figure 3-9). By tilting the engine slightly, the manufacturer can lower the height of the hood line for improvement in the vehicle’s aerodynamics. The V-type engine has two rows of cylinders set 60 to 90 degrees from each other (Figure 3-10). The V-type design allows for a shorter block height, thus easier vehicle aerodynamics. The length of the block is also shorter than in-line engines with the same number of cylinders. Another common engine design is the horizontally opposed cylinder engine, sometimes called a “boxer” engine (Figure 3-11). This engine design has two rows of cylinders directly across from each other. The main advantage of this engine design is the very low vertical height. Boxer engines are commonly used by Porsche, Volkswagen, and Subaru.

8 cylinder

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A transverse-mounted engine faces from side to side instead of front to back. The opposed cylinder engine may be called a pancake engine.

6 cylinder

Figure 3-10 The V-type engine design allows for lower and shorter hood lines.

Figure 3-9 Slant cylinder design lowers the overall height of the engine.

Figure 3-11 Opposed cylinder engine design. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Valvetrain Type

An overhead valve (OHV) engine has the valves mounted in the cylinder head and the camshaft mounted in the block.

Engines can also be classified by their valvetrain types. The three most commonly used valvetrains are the following:

A dual overhead cam (DOHC) engine has two camshafts mounted above each cylinder head.

1. Overhead valve (OHV). The intake and exhaust valves are located in the cylinder head, while the camshaft and lifters are located in the engine block (Figure 3-12). Valvetrain components of this design include lifters, pushrods, and rocker arms. 2. Overhead cam (OHC). The intake and exhaust valves are located in the cylinder head along with the camshaft. The valves are operated directly by the camshaft and a follower, eliminating many of the moving parts required in the OHV engine. If a single camshaft is used in each cylinder head, the engine is classified as a single overhead cam (SOHC) engine. This designation is used even if the engine has two-cylinder heads with one camshaft each. 3. Dual overhead cam (DOHC). The DOHC uses separate camshafts for the intake and exhaust valves. A DOHC V-8 engine is equipped with a total of four camshafts (Figure 3-13).

Ignition Types A spark-ignition (SI) engine ignites the airfuel ratio in the combustion chamber by a spark across the spark plug electrodes (this engine is often fueled by gasoline, propane, ethanol, or natural gas). A compression-ignition (CI) engine ignites the air-fuel mixture in the cylinders from the heat of compression (this engine is often fueled by diesel fuel).

Most automotive engines use a mixture of gasoline and air, which is compressed and then ignited with a spark plug. This type of engine is referred to as a spark-ignition (SI) engine. Diesel engines, on the other hand, do not use spark plugs. The air-fuel mixture is ignited by the heat created during the compression stroke. These engines are referred to as compression-ignition (CI) engines. Spark-ignition engines may be further identified by the type of ignition system used. The older, less common design is called a distributor ignition (DI). This form of ignition uses a mechanical device to distribute the spark from one coil to the correct cylinder. Newer ignition systems tend to use multiple coils to deliver the spark to the cylinders. These systems are termed electronic-ignition (EI) systems. A form of EI is the coil on plug (COP) ignition system, where one coil sits on top of each spark plug to deliver the spark directly (Figure 3-14). Another type of EI is called a waste spark-ignition system, where one coil provides the spark to two cylinders.

Rocker arm

A coil is an electrical device that converts low voltage from the battery into a very high voltage that is able to push a spark across the gap of the spark plug.

Fulcrum (pivot point)

Pushrod Valve spring

Lifter

Valve

Camshaft

Figure 3-12 The overhead valve engine has been one of the most popular valve designs. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

Exhaust camshaft Hydraulic lash adjuster

Rocker arm

Intake camshaft

Fulcrum (pivot point)

Valve spring

Exhaust port

Intake port

Exhaust valve

Intake valve

Figure 3-13 The dual overhead camshaft engine places two camshafts in the cylinder head.

Figure 3-14 This late-model V-6 engine has a coil on top of each spark plug (this is the forward cylinder head).

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Fuel Injection Types Fuel injection systems use the PCM to control electromechanical devices, fuel injectors that deliver a closely controlled amount of fuel to the cylinders.

All new vehicles currently sold in the United States and Canada use a form of fuel  injection to deliver fuel to the engine. Fuel injectors spray just the right amount of fuel for each combustion event. The required amount of fuel injected is controlled and determined by the PCM, based on inputs on air, engine speed, and temperature, and other inputs that will be affected by how much fuel is injected. Most fuel injection systems deliver fuel into the intake system very close to the intake valve. These systems use one injector per cylinder and are termed multipoint fuel injection (MPFI). The fuel injector is located in the intake manifold. Many manufacturers refine this system to make sure that the injectors each fire on each cylinder’s intake stroke for excellent mixing of the air and fuel. These systems are called sequential fuel injection (SFI) systems because the injectors fire in the same sequence as the cylinders. A few newer gas engines use fuel injectors that spray fuel directly into the combustion chamber and are located in the cylinder head. These are called gasoline direct injection (GDI) systems. This type of fuel injection improves combustion and reduces fuel consumption and emissions. Most compression-ignition diesel engines use a similar fuel injection method as the GDI system.

ENGINE VIBRATION Balance Shafts Many engine designs have inherent vibrations. The in-line four-cylinder engine is an example of this problem. Some engine manufacturers use balance shafts to counteract engine vibration. Four-cylinder engine vibration occurs at two positions of piston travel. The first is when a piston reaches TDC. The inertia of the piston moving upward creates an upward force in the engine. The second vibration occurs when all pistons are level. At this point, the downward-moving pistons have accelerated and have traveled more than half their travel distance. The engine forces are downward because the pistons have been accelerating since they have to travel a greater distance than the upward-moving pistons to reach the point at which all pistons are level. Piston travel is farther at the top 90 degrees versus the bottom 90 degrees of crankshaft rotation. First, determine the total length. This is rod length, from the center of the big end to the center of the small end, and the crankshaft throw (stroke divided by 2). Next, determine the amount the piston drops in the first 90 degrees of crankshaft rotation (TDC to 90 degrees). Once this is known, the final amount of piston travel can be determined. The balance shafts rotate at twice the speed of the crankshaft. This creates a force that counteracts crankshaft vibrations. At TDC, the force of the piston will exert upward; to offset the vibration, the crankshaft and the balance shaft(s) lobes have a downward force (Figure 3-15). At 90 degrees of crankshaft rotation, all pistons are level. Remember, the pistons traveling downward have traveled more than half of their travel distance to reach this point. The engine forces are in a downward direction since these pistons have been accelerated to reach the midpoint at the same time as the upward-moving pistons, which need to travel a lesser distance. Since the balance shaft(s) rotates at twice the crankshaft speed, the lobes of the balance shaft(s) are facing up, exerting an upward force to counteract the downward force of the pistons (Figure 3-16). At 180 degrees of crankshaft rotation, the upward-moving pistons reach TDC and again exert an upward force. The balance shaft(s) have their lobes facing downward to exert a downward force to counteract the upward force (Figure 3-15). Finally, at 270 degrees of crankshaft rotation, the pistons are level again. At this point, the lobes of the balance shaft(s) are exerting an upward force Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

to counteract the downward force of the pistons (Figure 3-16). Some modern diesel engines use a pulsing fuel injection as part of a strategy to smooth out the vibrations of the engine. Diesel engines generally produce more power on the power stroke and therefore have more inherent vibration problems. Balance shafts may also be used in V-type engines (Figure 3-17). Some balance shafts on OHV engines are mounted in the block V above the camshaft (Figure 3-18). Bearing journals on the balance shaft are mounted on bushings in the block. Some engines use two gears mounted on the front end of the camshaft to drive the balance shaft. The inner camshaft gear is meshed with the gear on the balance shaft, and the timing chain surrounds the outer camshaft gear and the crankshaft gear to drive the camshaft. On some DOHC engines, the balance shaft is mounted in the block above the crankshaft (Figure 3-19). Upward force

Downward force

Crankshaft Upward force

Balance shafts

Figure 3-16 Balance shaft operation with piston moving downward.

Downward force

Figure 3-15 Balance shaft operation with piston moving upward. Retainer

Plug Balance shaft

Gear

Figure 3-17 A balance shaft used in an OHV engine. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3 Bore (inches) TDC

Counter balance shaft

Stroke (inches)

BDC

Cubic inches, cubic centimeters, or liters

FRT

Figure 3-18 A balance shaft used in a DOHC V-6 engine.

Figure 3-19 Displacement is the volume of the cylinder between TDC and BDC.

AUTHOR’S NOTE One time a student drove his freshly rebuilt engine into the shop to have me look at why it “shook” so badly. The student said the engine ran well and had plenty of power but had a very significant vibration throughout the engine rpm (revolutions per minute) range. We took a test drive to verify the concern and tested the engine and transmission mounts. During further discussion, I realized the engine had balance shafts and asked the student if he had lined them up according to the marks described in the service information. Unfortunately, he was unaware of that necessary step. Once he successfully timed his balance shafts, his “new” engine ran beautifully.

ENGINE DISPLACEMENT Displacement is the measure of engine volume. The larger the displacement, the greater the power output.

A bore is the diameter of a hole. If the bore is larger than its stroke, the engine is referred to as oversquare. If the bore is smaller than the stroke, the engine is referred to as undersquare. A square engine has the same bore size as it does stroke. Stroke is the distance that the piston travels from TDC to BDC or vice versa. Some engine enthusiasts say “there is no replacement for displacement.”

Displacement is the volume of the cylinder between TDC and BDC measured in cubic inches, cubic centimeters, or liters (Figure 3-19). Most engines today are identified by their displacement in liters. Engine displacement is an indicator of engine size and power output. The more fuel (mixed with air) that can be burned, the greater the amount of energy that can be produced. For more fuel to burn, more air must also enter the cylinders. Engine displacement measurements are an indicator of the amount or mass of air that can enter the engine. The mass of air allowed to enter the cylinders is controlled by a throttle plate. If the throttle plate is closed, a smaller mass of air is allowed to enter the cylinder, and the power output is reduced. As the throttle plate is opened, the mass of air allowed to enter the cylinders is increased, resulting in greater power output. The more air that is allowed, the more fuel that can be added to it. As engine speed increases, it will eventually reach a point at which no more air can enter. Any increase in speed beyond this point causes a loss in power output. The major factor in determining the maximum mass of air that can enter the cylinders is engine displacement. The amount of displacement is determined by the number of cylinders, cylinder bore, and length of the piston stroke (Figure 3-20). Bore and Stroke. The bore of the cylinder is its diameter measured in inches (in.) or millimeters (mm). The stroke is the amount of piston travel from TDC to BDC measured in inches or millimeters. An oversquare engine is used when high rpm (revolutions per minute) output is required. This meets the requirements of many automotive engines. Most truck engines are designed as undersquare since they deliver more lowend torque.

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Theory of Engine Operation

Bore

Stroke

CL Crank

Piston at BDC (bottom dead center)

Piston at TDC (top dead center)

Figure 3-20 The bore and stroke determine the amount of displacement of the cylinder.

Calculating Engine Displacement Mathematical formulas can be used to determine the displacement of an engine. As with many mathematical formulas, more than one method can be used. The first is as follows: Engine displacement 5 0.785 3 B 2 3 S 3 N where 0.785 is a constant B 5 bore S 5 stroke N 5 number of cylinders The second formula is: Engine displacement 5 p 3 R 2 3 S 3 N where p 5 3.1416 R 5 bore radius (diameter/2) S 5 stroke length N 5 number of cylinders Pi times the radius squared is equal to the area of the cylinder cross section. This area is then multiplied by the stroke, and this product is multiplied by the number of cylinders. The calculation for total cubic inch displacement (CID) of a V-6 engine with a bore size of 3.800 inches (9.65 cm) and stroke length of 3.400 inches (8.64 cm) would be as follows: Engine displacement 5 0.785 3 3.800 2 3 3.400 3 6 5 231.24 CID or Engine displacement 5 3.1416 3 1.9 2 3 3.400 3 6 5 231.35 CID The difference in decimal values is due to rounding pi to four digits. Round the  product  to the nearest whole number. In this case, the CID would be expressed as 231. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Crank throw

CL Journal CL Crank

Figure 3-21 An alternate method of determining the piston stroke is to double the crankshaft throw.

Most engine manufacturers designate engine size by metric displacement. To calculate engine displacement in cubic centimeters or liters, simply use the metric measurements in the displacement formula. In the preceding example, the result would be 3,789.56 cc, which would be rounded off to 3.8 liters. Another way to convert to metric measurements is to use the CID and multiply it by .01639 to find the size of the engine in liters. For example, 231 3 .01639 5 3.79, or 3.8 liters. Use a service manual to determine the bore and stroke of the engine. An alternate method of determining the stroke is to measure the amount of crankshaft throw (Figure 3-21). The stroke of the engine is twice the crankshaft throw. You can measure the diameter of the cylinder to find the bore size. If the engine is machined or modified during the engine rebuild process, the engine displacement will change. For example, during the inspection process, an engine rebuild technician may find that the cylinders need to be bored out 0.060 inch (0.1524 cm). This new cylinder size would have to be included in the new displacement calculation.

DIRECTION OF CRANKSHAFT ROTATION The Society of Automotive Engineers (SAE) standard for engine rotation is counterclockwise when viewed from the rear of the engine (flywheel side). When viewing the engine from the front, the rotation of the crankshaft is clockwise. Most automotive engines rotate in this direction, but a few engines rotate the opposite direction. Some marine, older Volkswagen, and Honda engines are known as reverse rotation engines.

ENGINE MEASUREMENTS

The compression ratio is a comparison between the volume above the piston at BDC and the volume above the piston at TDC. Compression ratio is the measure used to indicate the amount the piston compresses each intake charge.

As discussed previously, engine displacement is a measurement used to determine the output of the engine and can be used to identify the engine. Other engine measurements include compression ratio, horsepower, torque, and engine efficiency. Some of these are also used to identify the engine; for example, an engine with 3.8 liters displacement may be available in different horsepower and torque ratings.

Compression Ratio The compression ratio expresses a comparison between the volume the air-fuel mixture is compressed into at TDC and the total volume of the cylinder (piston at BDC). The ratio is the result of dividing the total volume of the cylinder by the volume with the piston at TDC (Figure 3-22).

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Theory of Engine Operation Volume before compression: 480 cc

43

Volume after compression: 60 cc TDC

BDC

Compression ratio: 8 to 1

Figure 3-22 The compression ratio is a measurement of the amount the air-fuel mixture will be compressed. Torque 5 1 foot 3 10 pounds 5 10 foot-pounds Torque 5 2 feet 3 10 pounds 5 20 foot-pounds

Compression ratios affect engine efficiency. Higher compression ratios result in increased cylinder pressures, which compress the air-fuel molecules tighter. This is desirable because it causes the flame to travel faster. A higher compression ratio may be desirable because the mechanical efficiency is higher and typically more power will be produced from the same displacement. There are some drawbacks to just having higher compression ratios, such as a higher octane fuel requirement and increased emissions. These are unwanted outcomes of higher compression ratio engines. However, some modern engines have been able to increase the compression ratio while still allowing for the use of regular octane fuel and having similar emission levels. The use of a VVT system or a variable length manifold, along with alternative fuels and advanced computer programs, have given design engineers more flexibility when designing higher compression ratio engines. Theoretically, more power can be produced from a higher compression ratio. An increase in the compression ratio results in a higher degree of compression. Combustion occurs at a faster rate because the molecules of the air-fuel mixture are packed tighter. It is possible to change the compression ratio of an engine by performing some machining operations or changing piston designs. Increasing the compression ratio may increase the power output of the engine, but the higher compression ratio increases the compression temperature. This can cause preignition and detonation. To counteract this tendency, higher octane gasoline must be used. A higher octane fuel will burn slower than a lower octane fuel. The octane number of a fuel is also known as the antiknock index; the higher the number, the more resistant to knock, or detonation, the fuel is. Most gas automotive engines have a compression ratio between 8:1 (expressed as “eight to one”) and 10:1 and develop dry cylinder pressures during compression of between 125 and 200 psi. Diesel engines typically have compression ratios between 17:1 and 22:1. They can produce up to 600 psi of dry compression pressure. The usable compression ratio of an engine is determined by the following factors: ■ The temperature at which the fuel will ignite ■ The temperature of the air charge entering the engine ■ The density of the air charge ■ Combustion chamber design

Preignition is an explosion in the combustion chamber resulting from the air-fuel mixture igniting prior to the spark being delivered from the ignition system. Detonation is different from preignition. It is characterized as abnormal combustion. Detonation occurs when pressure and temperature build in gas chambers outside of the normal spark flame. This may be caused by improper octane, high engine loads, or improper combustion. Detonation is often known as “spark knock” or “pinging.”

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Calculating Compression Ratio When calculating the total volume above the piston, the combustion chamber in the  cylinder head must also be considered. The formula for calculating compression ratio is: CR 5 (VBDC 1 VCH)/(VTDC 1 VCH) where CR 5 compression ratio VBDC 5 volume above the piston at BDC VCH 5 combustion chamber volume in the cylinder head VTDC 5 volume above the piston at TDC Example : VBDC 5 56 cubic inches VCH 5 4.5 cubic inches VTDC 5 1.5 cubic inches The compression ratio would be: 56 1 4 : 5 1 : 5 1 4 : 5 5 10 : 1 During an engine rebuild, certain machining procedures may affect the compression ratio. Some examples of this would be resurfacing the cylinder head, resizing or boring the cylinders, and installing a different crankshaft. The compression ratio should always be considered when making choices during an engine rebuild.

Horsepower and Torque Torque is a mathematical expression for rotating or twisting force around a pivot point. As the pistons are forced downward, this pressure is applied to a crankshaft that rotates. The crankshaft transmits this torque to the drivetrain and ultimately to the drive wheels. Horsepower is the rate at which an engine produces torque. To convert terms of force applied in a straight line to force applied rotationally, the formula is: torque 5 force 3 radius If a 10-pound force is applied to a wrench 1 foot in length, 10 foot-pounds (ft.-lb.) of torque is produced. If the same 10-pound force is applied to a wrench 2 feet in length, the torque produced is 20 ft.-lb. (Figure 3-23).

Force 10 pounds Torque exerted on bolt 1 foot radius Torque = 1 foot 3 10 pounds = 10 foot-pounds

Force 10 pounds

2 feet radius Torque = 2 feet 3 10 pounds = 20 foot-pounds

Figure 3-23 Example of how torque can be increased. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

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Power is the rate at which work is done. The power an engine produces is rated in horsepower. Horsepower is a term that can be used to measure many mechanical actions. When discussing engines, we are measuring mechanical horsepower. One horsepower is equal to 33,000 foot-pounds per minute. The horsepower of an engine can be measured on a dynamometer, which places a load on the engine and measures torque. Knowing the torque of an engine and the rpm (engine speed) at which it was measured, you can calculate horsepower by using the following equation. Horsepower 5

torque 3 rpm 5,252

Torque and horsepower will peak at some point in the rpm range (Figure 3-24). This graph is a mathematical representation of the relationship between torque and horsepower in one engine. The graph indicates that this engine’s torque peaks at about 1,700 rpm, while brake horsepower peaks at about 3,500 rpm. The third line in the graph represents the amount of horsepower required to overcome internal resistances or friction in the engine. The amount of brake horsepower is less than indicated horsepower due to this and other factors. The SAE standards for measuring horsepower include ratings for gross and net horsepower. Gross horsepower expresses the maximum power developed by the engine without additional accessories operating. These accessories include the air cleaner and filter, cooling fan, charging system, and exhaust system. Net horsepower expresses the amount of horsepower the engine develops as installed in the vehicle. Net horsepower is about 20 percent lower than gross horsepower. Most manufacturers express horsepower as SAE net horsepower. For example, if the torque of the engine is measured at the following values, a graph can be plotted to show the relationship between torque and horsepower (Figure 3-25):

Indicated horsepower is the amount of horsepower the engine can theoretically produce. Gross horsepower is the maximum power that an engine can develop. It is measured without additional accessories installed (such as belt-driven items and the transmission).

300

100

250

80

200

60

150

40

100

20

50

1

2

3

4

5

Net horsepower is the amount of horsepower an engine has when it is installed in the vehicle. Foot-pounds of torque

Horsepower

120

Brake horsepower is the usable power produced by an engine. It is measured on a dynamometer using a brake to load the engine.

6

Engine rpm (x 1000) Brake horsepower Torque Friction horsepower

Figure 3-24 Example of torque and horsepower curves. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3 300

Horsepower foot-pounds of torque

250

200

150

100

50

1

2

3 4 5 Engine rpm (x1000)

6

7

Horsepower Torque

Figure 3-25 It is possible to graph the relationship between torque and horsepower. Highest torque output is usually at lower engine speeds, while peak horsepower is at higher engine speeds.

Torque output @ 1,500 rpm 5 105 lb.-ft. Torque output @ 2,800 rpm 5 110 lb.-ft. Torque output @ 3,500 rpm 5 115 lb.-ft. Torque output @ 5,000 rpm 5 130 lb.-ft. Torque output @ 6,000 rpm 5 125 lb.-ft. Torque output @ 6,500 rpm 5 100 lb.-ft. In this instance, the horsepower is as follows: Horsepower @ 1,500 rpm Horsepower @ 2,800 rpm Horsepower @ 3,500 rpm Horsepower @ 5,000 rpm Horsepower @ 6,000 rpm Horsepower @ 6,500 rpm Efficiency is a measure of a device’s ability to convert energy into work. The mechanical efficiency of an engine is the comparison between actual power measured at the crankshaft and the actual power developed within the cylinders. There will always be frictional losses in the crankshaft, cylinders, and connecting rods.

5 5 5 5 5 5

30 59 77 124 143 124

Engine Efficiency Several different measurements are used to describe the efficiency. Efficiency is mathematically expressed as output divided by input. The terms used to define the input and output must be the same. Some of the most common efficiencies of concern are mechanical, volumetric, and thermal efficiencies. Mechanical efficiency is a comparison between brake horsepower and indicated horsepower; in other words, it is a ratio of the power actually delivered by the crankshaft to the power developed within the cylinders at the same rpm. The formula used to calculate mechanical efficiency is: Mechanical efficiency 5 brake horsepower/indicated horsepower Ideally, mechanical efficiency would be 100 percent. However, the power delivered will always be less due to power lost in overcoming friction between moving parts in the engine. The mechanical efficiency of an internal combustion four-stroke engine is

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Theory of Engine Operation

approximately 90 percent. If the engine’s brake horsepower is 120 hp and the indicated horsepower is 140 hp, the mechanical efficiency of the engine is 85.7 percent. Mechanical efficiency is a top concern for engine developers. Increasing the mechanical efficiency can increase the power output and allow for a smaller, more efficient engine to be installed into a larger vehicle. Low-friction lubricants, small manufacturing tolerances, and precision manufacturing are just a few examples of the techniques of how engine developers are increasing engine efficiency. Volumetric efficiency (VE) is a measurement of the amount of air-fuel mixture that actually enters the combustion chamber compared to the amount that could be ingested at that speed. Volumetric efficiency describes how well an engine can breathe. The more air an engine can take in, the more power the engine will put out. As the volumetric efficiency increases, the power developed by the engine increases proportionately. The formula for determining volumetric efficiency is:

47

Volumetric efficiency is the comparison between the amount of air that could enter the engine and the amount of air that actually enters the engine.

Actual volume of air in cylinder Maximum volume of air in cylinder An example of a calculation for volumetric efficiency is an engine with a 350 CID displacement that actually has an air-fuel volume of 341 cubic inches at a particular rpm. The actual amount of air taken in is less than the available space; this engine is 97 percent volumetrically efficient at this rpm.

A BIT OF HISTORY The term horsepower was coined by James Watt (1736–1819). Mr. Watt was working with the first practical steam-powered engines. Steam engines were on the verge of replacing horses for doing some of the work. At the time, miners, farmers, and other industries were using horses to do most of their work. Mr. Watt was working with mine ponies who were used to lift coal out of a mine. He figured that on average a pony could pull 220 pounds a distance of 100 feet in one minute. He then judged that horses were 50 percent stronger than ponies, and thus he arrived at the equation 1 horsepower = 33,000 foot pounds of work per minute. James Watt and Matthew Boulton standardized this measurement in 1783.

Ideally, 100 percent volumetric efficiency is desired, but actual efficiency is reduced due to pumping losses. It must be realized that a given mass of air-fuel mixture occupies different volumes under different conditions. Atmospheric pressures and temperatures will affect the volume of the mixture. Pumping losses are the result of restrictions to the flow of air-fuel mixture into the engine. These restrictions are the result of intake manifold passages, throttle plate opening, valves, and cylinder head passages. There are some machining techniques used by builders of performance engines that will reduce these restrictions. Pumping losses are influenced by engine speed; for example, an engine may have a volumetric efficiency of 75 percent at 1,000 rpm and increase to an efficiency of 85 percent at 2,000 rpm, then drop to 60 percent at 3,000 rpm. As engine speed increases, volumetric efficiency may drop to 50 percent. If the airflow is drawn in at a low engine speed, the cylinders can be filled close to capacity. A required amount of time is needed for the airflow to pass through the intake manifold and pass the intake valve to fill the cylinder. As engine speed increases, the amount of time the intake valve is open is not long enough to allow the cylinder to be filled. Because of the effect of engine speed on volumetric efficiency, engine manufacturers use intake manifold design, valve port design, valve size, multiple valves, valve overlap, camshaft timing, exhaust tuning, variable length manifolds, and computer control to improve the engine’s breathing. Current production models have fast computers that can calculate the volumetric efficiency by using computer data. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3

Thermal efficiency is the difference between potential and actual energy developed in a fuel measured in Btus per pound or gallon.

The VE of a typical modern spark ignition internal combustion normally aspirated engine is 75 to 95 percent. There are some examples of naturally aspirated engines having more than 100 percent VE. Older engines were limited in their designs and did not employ the same criteria of their modern counterparts. Today, many engines have four valves per cylinder, whereas an engine made in 1970 typically has only two valves per cylinder. A turbocharger or supercharger will force air into the engine (called forced induction). This process will also give the engine a VE of over 100 percent. Other factors of VE are elevation, temperature, fuel type, and humidity. A higher VE is desired because it means less pumping and parasitic losses and greater power output of the engine. Volumetric efficiency should not be confused with the total engine efficiency, although it does have a great influence on it. Thermal efficiency is a measurement comparing the amount of energy present in a fuel and the actual energy output of the engine. Thermal efficiency is the measurement of how much energy is actually used to turn the wheels as compared to the total energy available. Heat is a form of energy just like electricity. Heat energy can be measured using two terms: intensity and quantity. The measurement of the intensity of heat energy is measured in the temperature scale (Celsius or Fahrenheit). Temperature is the measurement of an object’s internal energy. Something that is hot has more heat intensity than something that is cold; therefore, it has more heat intensity and more heat energy. For example, we may say that a liquid is hot because it is 2008F. This just means that it has a higher temperature than another familiar object. Heat quantity (often referred to as heat value or heat’s power) is the amount of heat energy a piece of matter has. The most commonly used units for measuring heat quantity are the Btu, the calorie (c), and the joule (J). One Btu is the amount of heat required to raise the temperature of 1 pound of pure liquid water by 18F. The temperature at which water has its greatest density is 398F. Testing for a Btu is done at this temperature. One Btu is equal to 1,055 J or 252 C. Some of the different fuels used for internal combustion engines and their energy content are in the following list. Keep in mind that each of these values will vary with different mixtures, seasons, manufacturers, retailers, and geographic location. 1 gallon of midgrade gasoline 5 108,500 2 117,000 Btus 1 gallon of ethanol fuel 5 76,100 Btus 1 gallon of no. 2 diesel 5 139,000 Btus 1 gallon of propane 5 91,600 Btus The formula used to determine a gasoline engine’s thermal efficiency has a couple of constants. First, 1 hp equals 42.4 Btus per minute. Second, gasoline has approximately 110,000 Btus per gallon. Knowing this, the formula is as follows: Thermal efficiency 5 ( bhp 2 42.4 Bpmin ) / (110,000 Bpg 2 gpmin ) where bhp 5 brake horsepower Bpmin 5 Btu per minute Bpg 5 Btu per gallon gpmin 5 gallons used per minute As a whole, gasoline engines waste about two-thirds of the heat energy available in gasoline. Approximately one-third of the heat energy is carried away by the engine’s cooling system. This is required to prevent the engine from overheating. Another third is lost in hot exhaust gases. The remaining third of heat energy is reduced by about 5 percent due to friction inside of the engine. Another 10 percent is lost due to friction in drivetrain components. Due to all of the losses of heat energy, only about 19 percent is actually applied to the driving wheels. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

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Of the 19 percent applied to the driving wheels, an additional amount is lost due to the rolling resistance of the tires against the road. Resistance to the vehicle moving through the air requires more of this energy. By the time the vehicle is actually moving, the overall vehicle efficiency is about 15 percent. Manufacturers are continuing to increase the thermal efficiency of the engine in hopes that it will help increase fuel economy. As you begin to work with engines, you will be able to compare older engines to modern engines and identify different parts and computermanagement strategies that have been employed to increase thermal efficiency.

OTHER ENGINE DESIGNS Two-Stroke Engines Throughout the history of the automobile, the gasoline four-stroke internal combustion engine has been the standard. As technology has improved, other engine designs have been used. This section of the chapter provides an overview of some of these other engine designs. Two-stroke engines are capable of producing a power stroke every revolution. Valves are not used in most two-stroke engines; instead, the piston movement covers and uncovers intake and exhaust ports. The air-fuel mixture enters the crankcase through a reed valve or rotary valve (Figure 3-26). Upward movement of the piston causes pressure to increase in the cylinder above the piston and creates a slight vacuum below the piston. Atmospheric pressure pushes the air-fuel mixture into the low-pressure area below the piston. At the same time, a previously ingested air-fuel mixture is being compressed above the piston. This action combines the compression stroke and intake stroke. When the compressed air-fuel mixture is ignited, the piston moves down the cylinder. This slightly compresses the air-fuel mixture in the crankcase. The air-fuel mixture in the crankcase is directed to the top of the piston through the transfer port to the intake port. The reed valve or rotary valve closes to prevent the mixture from escaping from the crankcase. The downward piston movement opens the exhaust port, and the pressure of the expanding gases pushes out the spent emissions. Continued downward movement of the piston uncovers the intake port and allows the air-fuel mixture to enter above the piston. This action combines the power and exhaust strokes. Most gasoline two-stroke engines do not use the crankcase as a sump for oil, since it is used for air-fuel intake. To provide lubrication to the engine, the oil must be mixed with

A reed value is a oneway check valve. The reed opens to allow the air-fuel mixture to enter from one direction, while closing to prevent movement in the other direction. A rotary valve is a valve that rotates to cover and uncover the intake port.

Transfer port

Transfer port Exhaust port

Exhaust port

Air-fuel mixture

Air-fuel mixture

Reed valve

Reed valve

Figure 3-26 Two-stroke cycle engine design. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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the fuel or injected into the crankcase. This results in excessive exhaust emissions. Dieseldesign two-stroke engines may have a sump. Many automotive engine manufacturers are trying to find ways to reduce the emission levels of the two-stroke engine to allow for its use in automobiles. The advantage of the two-stroke engine is that it produces more power per cubic inch of displacement than the four-stroke engine. Today, two-stroke engines are mostly used in small applications, such as lawn and garden equipment, and recreational and sports applications (snowmobiles, ATVs, watercraft, etc.). Although they are being quickly phased out by four-stroke diesel engines because of their greater efficiency and lower emissions. There have been a few automobiles, light trucks, and heavy trucks produced in the past that used two-stroke engines. One very famous example of this comes from the Detroit Diesel Company, which produced many two-stroke diesel engines for many military and on-highway commercial applications.

Diesel Engines

Glow plugs are threaded into the combustion chamber and use electrical current to heat the intake air on diesel engines.

The first diesel engine was operated and invented by Rudolf Diesel in 1897. Since then, diesel engines have been mainly used in heavy-duty applications, including light-, medium-, and heavy-duty trucks, vans, tractors, and semis. Diesels used in marine and standby generator applications are desirable for their power output, low fuel consumption, and longevity. Diesel engines tend to be built heavier and often cost more to manufacture. Domestic automobiles had a few diesel engine options for a few years, but the engine option in small cars has not sold very well over the past few decades with American consumers. Within recent years, the domestic pickup truck market has more widely accepted the diesel engine option. The more powerful and fuel-efficient diesel engine designs are suited well in pickups where the noise, vibration, and harshness level expectations are lower than they are for cars. By contrast, European automobiles are mostly powered by diesel engines and have been for many years. Within the last few years of the publish date of this book, the number of diesel engines in cars and light trucks has been increasing significantly. Examples of such vehicles with popular diesel engine options are Volkswagen cars and domestic light-duty trucks. The diesel engine in these vehicles is also popular in the North American market as well. Diesel and gasoline engines have many similar components; however, the diesel engine does not use an ignition system consisting of spark plugs and coils. Instead of using a spark initiated and developed by the ignition system, the diesel engine uses the heat produced by compressing air in the combustion chamber to raise the temperature of the air (not the fuel) closer to (and sometimes above) the autoignition temperature of the fuel. Once the fuel is injected under high pressure, it instantly increases in temperature because of its contact with the high temperature air in the combustion chamber. This begins the combustion process of the diesel fuel in the power stroke (Figure 3-27). This explains why diesel engines have a higher compression ratio when compared to gasoline engines. Diesel engines are also categorized as CI (compression ignition) engines. Because starting the diesel engine is dependent on heating the intake air to a high enough level to ignite the fuel, a method of preheating the intake air is required to start a cold engine. Some manufacturers use glow plugs to accomplish this. Another method includes using a heater grid in the air intake system. In addition to ignition methods, there are other differences between gasoline and diesel engines (Figure 3-28). The combustion chambers of the diesel engine are designed to accommodate the different burning characteristics of diesel fuel. There are three common combustion chamber designs: 1. An open-type combustion chamber is located directly inside of the piston. The fuel is injected directly into the center of the chamber. Turbulence is produced by the shape of the chamber.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

Intake

Compression

Power

Exhaust

Figure 3-27 The four strokes of a diesel engine.

2. A precombustion chamber is a smaller second chamber connected to the main combustion chamber. Fuel is injected into the precombustion chamber, where the combustion process is started. Combustion then spreads to the main chamber. Since the fuel is not injected directly on top of the piston, this type of diesel injection may be called indirect injection. 3. A turbulence combustion chamber is a chamber designed to create turbulence as the piston compresses the air. When the fuel is injected into the turbulent air, a more efficient burn is achieved. Diesel engines can be either four-stroke or two-stroke designs, although like gas engines, production automotive applications currently use four-stroke engines. Twostroke engines complete all cycles in two strokes of the piston, much like a gasoline twostroke engine. Diesel engines typically have lower fuel consumption rates and a high-power output (compared to a same displacement gasoline engine). Many manufacturers are considering diesel engines as options for their line of cars. Diesel engines operate similarly to gasoline engines and have extra operating components to support clean and efficient operation. It is very common to rebuild a diesel engine in heavy commercial applications because the cost of total engine replacement is very high and the cost of vehicle replacement is even higher.

Gasoline

Diesel

Intake

Air-fuel

Air

Compression

8–10 to 1, 130 psi 5458F

13–25 to 1, 400–600 psi 1,0008F

Air-fuel mixing point

Carburetor or before intake valve with fuel injection

Near TDC by injection

Combustion

Spark ignition

Compression ignition

Power

464 psi

1,200 psi

Exhaust

1,30021,8008F CO 5 3%

70029008F CO 5 0.5%

Efficiency

22%–28%

32%–38%

Figure 3-28 Comparisons between gasoline and diesel engines. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Intake valve rich mixture Intake valve lean mixture

Precombustion chamber

Combustion chamber

Figure 3-29 Stratified engine design.

Stratified Charge Engine The stratified charge engine uses a precombustion chamber to ignite the main combustion chamber (Figure 3-29). The advantage of this system is increased fuel economy and reduced emission levels. In this engine type, the air-fuel mixture is stratified to produce a small, rich mixture at the spark plug while providing a lean mixture to the main chamber. During the intake stroke, a very lean air-fuel mixture enters the main combustion chamber. At the same time, a very rich mixture is pushed past the auxiliary intake valve and into the precombustion chamber (Figure 3-30). At the completion of the compression stroke, the spark plug fires to ignite the rich mixture in the precombustion chamber. The burning rich mixture then ignites the lean mixture in the main combustion chamber. A stratified charge engine is in some ways similar to a diesel engine. The rich air-fuel mixture ignites easily in the precombustion chamber, which allows the excessively lean air-fuel mixture from the intake to ignite without detonation or preignition. This design has not been terribly successful in automobiles over the years, but manufacturers are still working toward a solution. One primary example of a stratified charge engine was the Honda CVCC engine produced in the 1970s. Honda’s CVCC engine lead to the development of other successful and efficient engines produced by other manufacturers, such as lean burn and direct injection designs.

ENGINE IDENTIFICATION Proper engine identification is required for the technician or machinist to obtain correct specifications, service procedures, and parts. The vehicle identification number (VIN) is one source for information concerning the engine. The VIN is located on a metal tag that is visible through the vehicle’s windshield (Figure 3-31). The VIN provides the technician with a variety of information concerning the vehicle (Figure 3-32). The eighth digit represents the engine code. The service information provides details for interpretation of the engine code. The VIN is also stamped in a number of other locations around the vehicle to make falsification more difficult. It is always important to make sure you get the correct engine code. Several vehicles have the same size engine but were available with different VIN codes. Not representing the eighth digit of the VIN correctly can cause issues with ordering parts, regular maintenance, specifications, and more. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

A

B

C

D

Figure 3-30 The stratified engine design uses a rich mixture in the precombustion chamber to ignite the lean mixture in the main chamber.

A vehicle code plate is also located on the vehicle body, usually inside the driver’s side door or under the hood. This plate provides information concerning paint codes, transmission codes, and so forth (Figure 3-33). The engine sales code is also stamped on the vehicle code plate. The engine itself may have different forms of identification tags or stamped numbers (Figure 3-34). In addition, color coding of engine labels may be used to indicate transitional low emission vehicles (TLEVs) and flex fuel vehicles (FFVs). These numbers may

Figure 3-31 The VIN number can be seen through the windshield. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3

1G2FS32P8RE100000 1 2

SEQUENCE NO.

ORIGIN USA CANADA

LAST 6 DIGITS PLANT CODE

MANUFACTURER G

E

4 5

MAKE CHEVROLET PONTIAC

2

FIREBIRD

N/E

GRAND AM

YEAR 2004 2005

CHECK DIGIT 9 TH DIGIT

VEHICLE LINE F/S

1 3

PONTIAC EAST

GENERAL MOTORS

ENGINE CODE L P

BODY 2 DR COUPE CONVERTIBLE

ENGINE V8 V8

RPO L27 LT1

FUEL SYS. MFI MFI

DISP. 3.8L 5.7L

RESTRAINT MANUAL BELTS WITH DRV / PASS INFLATABLE RESTRAINTS

Figure 3-32 The VIN number is used to provide the required information about the vehicle and engine.

AUTHOR’S NOTE One day I was working on an older import vehicle, and a police officer walked up to the car and explained that he had reason to believe this was a stolen vehicle. To check it out, he lifted the rear carpet in the trunk and compared the VIN with the VIN located on the dashboard. Neither appeared to have been tampered with, and the number did not match the VIN of the stolen vehicle. He left me to my work and went on his way to search for the real stolen vehicle.

provide build date codes required to order proper parts. Use the service information to determine the location of any engine identification tags or stamps and the methods to interpret them; for example, a Jeep engine with the build date code of *401HX23* identifies a 2.5-liter engine with a multipoint fuel injection system, 9:1 compression ratio, built on January 23, 1994. This is determined by the first digit representing the year of manufacture (4 5 1994). The second and third digits represent the month of manufacture (01 5 January). The fourth and fifth digits represent the engine type, fuel system, and compression ratio (HX 5 2.52liter engine with a multipoint fuel injection system, 9 : 1 compression ratio). The sixth and seventh digits represent the day of manufacture (23). Some engines are manufactured with oversized or undersized components. This occurs due to mass production of the engines. Components that may be different sizes than nominal include: ■ Cylinder bores ■ Camshaft bearing bores Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Theory of Engine Operation

VINYL ROOF CODE ORDER NUMBER VEH. MODEL NUMBER

XXX XXXXXXXXX

XXX

XXXXXX ENGINE CODE

XXX

XXXX

XXXX

XXXX

XX

PAINT PROCEDURE

INTERIOR CODE

PRIMARY PAINT

SECONDARY PAINT

XXX X

XXXXXXXXXXXXXXXXX

TRANSMISSION CODE

VIN

MARKET U-C-B-M CODE

Figure 3-33 Vehicle code plates provide sales code information about the vehicle. NOTE: VIN is stamped on the bedplate

Label located on valve cover 5.0 2355 743 2235

1234

743

DATE

SEQ NUM

B/CODE

3 PLT

Block foundry ID and date Engine number

Figure 3-34 The engine may have identification numbers stamped on it.

Crankshaft main bearing journals Connecting rod journals Engines with oversize or undersize components (from the factory) are usually identified by a letter code stamped on the engine block (Figure 3-35). This information is helpful when ordering parts and measuring for wear. ■ ■

Distributor

Letter code

Oil filter boss

Figure 3-35 Additional markings indicate if components are undersize or oversize. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 3

SUMMARY ■

■

■

■

One of the many laws of physics used within the automotive engine is thermodynamics. The driving force of the engine is the expansion of gases. Heat is generated by compressing the air-fuel mixture within the engine. Igniting the compressed mixture causes the heat, pressure, and expansion to multiply. Engine classification is usually based on the number of cycles, the number of cylinders, cylinder arrangement, and valvetrain type. In addition, engine displacement is used to identify the size of the engine. Most automotive and truck engines are four-stroke cycle engines. A stroke is the movement of the piston from BDC to TDC of the cylinder and is usually measured in inches or millimeters. The first stroke of the cycle is the intake stroke. The compression stroke begins as the piston starts its travel back to TDC. When the spark is introduced to the compressed mixture, the rapid burning causes the molecules to expand, and this is the beginning of the power stroke. The exhaust stroke

■

■

■

■

■

of the cycle begins with the upward movement of the piston back toward TDC and pushes out the exhaust gases from the cylinder past the exhaust valve and into the vehicle’s exhaust system. The three most commonly used valvetrains are the overhead valve (OHV), overhead cam (OHC), and dual overhead cam (DOHC). Other engine designs and features include twostroke, diesel, stratified charge, gasoline direct injection. Displacement is the total volume of the cylinder between BDC and TDC measured in cubic inches, cubic centimeters, or liters. Engine displacement is usually an indicator of the engine’s capability of producing power. Torque is a turning or twisting force. As the pistons are forced downward, this pressure is applied to a crankshaft that rotates. The crankshaft transmits this torque to the drivetrain and ultimately to the drive wheels. Horsepower is the rate at which an engine produces torque in a given amount of time.

REVIEW QUESTIONS Short-Answer Essays 1. Describe how the basic laws of thermodynamics are used to operate the automotive engine. 2. List and describe the four strokes of the fourstroke cycle engine. 3. Describe the different cylinder arrangements and the advantages of each. 4. Describe the different valvetrains used in modern engines. 5. What is engine displacement and how is it determined?

9. Explain the basic operation of the two-stroke engine. 10. Describe a situation where incorrectly identifying the eighth digit of the VIN may cause problems.

Fill-in-the-Blanks 1. Most automotive and truck engines are _______________ cycle engines. 2. During the intake stroke, the intake valve is _______________, while the exhaust valve is _______________.

6. Describe how the compression stroke of a gasoline four-stroke engine raises the temperature of the air-fuel mixture and why this step is so important.

3. The _______________ engine places all of the cylinders in a single row.

7. Define the term stroke, as used as part of the operation of an engine.

4. An _______________ _______________ engine has the valve mechanisms in the cylinder head, while the camshaft is located in the engine block.

8. Describe the differences of how the fuel and air are mixed and injected in a four-stroke diesel engine when compared to a four-stroke gasoline engine.

5. _______________ occurs when pressure and temperature build in gas chambers outside of the normal spark flame.

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Theory of Engine Operation

6. In a four-stroke engine, four strokes are required to complete one _______________. 7. Instead of using a spark produced by the ignition system, the diesel engine uses the _______________ produced by compressing air in the combustion chamber to ignite the fuel. 8. A _______________ _______________ engine has a power stroke every revolution. 9. In a two-cycle engine the air-fuel mixture enters the crankcase through a _______________ _______________ or _______________ _______________. 10. _______________ is an explosion in the combustion chamber resulting from the air-fuel mixture igniting prior to the spark being delivered from the ignition system.

Multiple Choice 1. Increasing the compression ratio of an engine is being discussed. Technician A says increased compression ratios result in a reduction of power produced. Technician B says higher compression ratio engines require higher octane gasoline. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Engine measurement is being discussed. Technician A says the bore is the distance the piston moves within the cylinder. Technician B says the stroke is the diameter of the cylinder. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. Technician A says to determine horsepower, torque must be known first. Technician B says horsepower will usually peak at a lower engine speed than torque. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

57

4. Technician A says mechanical efficiency is a comparison between brake horsepower and indicated horsepower. Technician B says volumetric efficiency is a measurement of the amount of air-fuel mixture that actually enters the combustion chamber compared to the amount that could be drawn in. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. During the compression stroke in a four-cycle engine A. the intake valve is open, and the exhaust valve is closed. B. the exhaust valve is open, and the intake valve is closed. C. both valves are open. D. both valves are closed. 6. All of these statements about diesel engines are true except: A. The air-fuel mixture is ignited by the heat of compression. B. Glow plugs may be used to heat the air-fuel mixture during cold starting. C. Spark plugs are located in each combustion chamber. D. Diesel engines may be two cycle or four cycle. 7. While discussing volumetric efficiency, Technician A says volumetric efficiency is not affected by intake manifold design. Technician B says volumetric efficiency decreases at high engine speeds. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. In a two-stroke cycle engine, A. a power stroke is produced every crankshaft revolution. B. intake and exhaust valves are located in the cylinder head. C. the lubricating oil is usually contained in the crankcase. D. the crankcase is not pressurized.

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Chapter 3

9. A vehicle with sequential fuel injection will A. inject fuel only once per engine cycle. B. inject fuel on every stroke of a four-stroke cycle. C. have one fuel injector that is used for all of the cylinders in a multicylinder engine. D. inject fuel all of the time when an engine is running.

10. While discussing engine identification, Technician A says that the tenth character of the VIN defines the vehicle model year. Technician B says that an engine identification tag may identify the date on which the engine was built. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 4

ENGINE OPERATING SYSTEMS

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■ ■ ■ ■

■ ■

The purpose of the starting system. The components of the starting system. The purpose of the battery. The purposes of the engine’s lubrication system. The operation of the lubrication system and its major components. The basic types and purposes of additives formulated into engine oil. The purpose of the Society of Automotive Engineers’ (SAE) classifications of oil. The purpose of the American Petroleum Institute’s (API) classifications of oil. The purpose of the International Lubricant Standardization and Approval Committee’s (ILSAC) classifications of oil.

■ ■ ■ ■ ■ ■ ■ ■

The two basic types of oil pumps: rotary and gear. The purpose of the cooling system. The operation of the cooling system and its major components. The advantages of a reverse-flow cooling system. The purpose of antifreeze and its characteristics. The purpose and basic operation of the fuel system. The purpose and basic operation of the ignition system. The purpose of the emission control systems.

Terms To Know Armature Battery terminals Body control module (BCM) Burn time C-class oil Cetane number Coolant recovery system Cooling system Detergents Diesel Distributor-ignition (DI) Electrolysis Electronic ignition (EI) Emission control system Ethanol Flexplate Flywheel Fuel system Full-filtration system

Gasoline Head gasket Heater core Ignition system Inlet check valve Jet valve Knock sensor Lubrication system Micron Motor Octane Number (MON) Multipoint fuel injection Nucleate boiling Octane Oil breakdown Oil cooler Oil pump Oil sludge Oxidation

Oxidation inhibitors Piezoresistive sensor Pole shoes Positive displacement pump Prove-out circuit Radiator Reverse-flow cooling system Ring gear Research Octane Number (RON) Saddle S-class oil Tetraethyl (TEL) lead Thermistor Thermostat Viscosity Viscosity index Warning light

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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INTRODUCTION There are five basic requirements for the engine to run: ■ The intake and exhaust systems must allow the engine to take air in and exhaust air out. ■ The fuel system must supply the correct amount of fuel to mix with the air. ■ The ignition system must deliver a spark to the cylinder at the correct time. ■ The engine must develop adequate compression to allow ignition of the air and fuel. ■ The electrical system must supply adequate electrical energy to start the engine and keep the auxiliary systems operating. To maintain engine operation, the lubrication system must reduce friction in the engine and provide cooling. The cooling system must regulate engine temperature and remove excess heat. The emissions control systems reduce the environmentally damaging evaporative and exhaust emissions from the vehicle. The proper operation of these supporting systems helps ensure the engine’s good performance, low emission output, efficiency, and longevity. In this chapter, we will discuss the purpose and operation of these systems and their components. The engine cannot run properly without fully functional supporting systems. Failures in the lubrication system, as an example, can cause very serious engine problems. As a professional technician, you will need to understand the operation of all the systems and components that keep the engine running properly. You will use this knowledge to help you provide excellent maintenance and perform expert diagnosis and repairs on the engine and its supporting systems.

THE STARTING SYSTEM The ring gear around the circumference of a flywheel or flexplate allows the starter motor drive gear to turn the engine. Some flexplates and flywheels are used as part of a sensor to determine the speed of the engine. The flywheel is a heavy disk mounted at the end of the crankshaft to make the engine power pulses and vibrations more stable. It has a smooth surface to which the clutch assembly of a manual transmission is attached. This smooth surface is similar to the surface of a brake rotor. A flexplate is a lighter version of a flywheel and is bolted to the torque converter of an automatic transmission.

The internal combustion engine must be rotated before it will run under its own power. It will need to build up speed and momentum before the ignition and fuel system can successfully take over and run the engine. The starting system is a combination of mechanical and electrical parts working together to start the engine. The starting system is designed to change the electrical energy that is being stored in the battery into mechanical energy. For this conversion to be accomplished, a starter or cranking motor is used. The conventional starting system includes the following components (Figure 4-1): 1. 2. 3. 4. 5. 6. 7.

Battery Cable and wires Ignition switch Starter solenoid or relay Starter motor Starter drive and flywheel ring gear Starting safety switch

The battery delivers electrical power to the starter solenoid when the driver turns the ignition key to the crank position. The solenoid delivers battery power to the starter motor. The starter motor drive gear is engaged with the ring gear on the flywheel or flexplate; the flywheel (or flexplate) is bolted to the engine’s crankshaft. When the starter motor spins, it rotates the engine at about 200–250 rpm (Figure 4-2). This is fast enough to allow the four-stroke cycle to produce sustainable combustion and begin running under its own power. Many newer vehicles have computer modules and antitheft systems installed on them. These computers are used to help control the engine’s starting procedures.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems Start switch

Neutral safety switch

Battery

Solenoid

B S

Flywheel Cranking motor

Figure 4-1 The major components of a typical starting system.

Figure 4-2 A typical permanent magnet starter; it is more compact than a starter with pole shoes and field windings.

The starting system of a hybrid electric vehicle (HEV) is different from the normal starting system. The high-voltage battery pack is typically used to start the gasoline engine. The same set of electric motors that are used for propulsion are used in conjunction with a gear set to start the gasoline engine. Special care must be taken when servicing these vehicles. This is explained in Chapter 14 of the Shop Manual.

A BIT OF HISTORY In the early days of the automobile, the vehicle did not have a starter motor. The operator had to use a starting crank to turn the engine by hand. Charles F. Kettering invented the first electric “self-starter,” which was developed and built by Delco Electric. The self-starter first appeared on the 1912 Cadillac and was actually a combination starter and generator.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

The Battery

Battery terminals provide a means of connecting the battery plates to the vehicle’s electrical system.

An automotive battery is an electrochemical device that provides for and stores potential electrical energy. When the battery is connected to an external load such as a starter motor, an energy conversion occurs, causing an electric current to flow through the circuit. Electrical energy is produced in the battery by the chemical reaction that occurs between two dissimilar plates that are immersed in an electrolyte solution. When discharging the battery (current flowing away from the battery), the battery changes chemical energy into electrical energy. It is through this change that the battery releases stored energy. During charging (current flowing from the charging system to the battery), electrical energy is converted into chemical energy. Because of this, the battery can store energy until it is needed. The largest demand is placed on the battery when it must supply current to operate the starter motor. The amperage requirements of a starter motor may be over 200 amperes. This requirement is also affected by temperature, engine size, and starter and engine condition. A typical 12-volt automotive battery is made up of six cells connected in series (Figure 4-3). The six cells produce 2.1 volts each. Wiring the cells in series produces the 12.6 volts required by the automotive electrical system. A fully charged battery has 12.6 volts. The cell elements are submerged in a cell case that is filled with electrolyte solution. All automotive batteries have two terminals. One terminal is a positive connection; the other is a negative connection. The battery terminals extend through the cover or the side of the battery case. Following are the most common types of battery terminals (Figure 4-4): 1. Post or top terminals. Used on most automotive batteries. The positive post is larger than the negative post to prevent connecting the battery in reverse polarity. 2. Side terminals. Positioned in the side of the container near the top. These terminals are threaded and require a special bolt to connect the cables. Polarity identification is by positive and negative symbols. 3. L-terminals. Used on specialty batteries and some imports.

12 Volts

Figure 4-3 The 12-volt battery consists of six 2-volt cells connected together.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

Side terminal

Post or top terminal

“L” terminal

Figure 4-4 The most common types of automotive battery terminals.

Temperature

% of Cranking Power

80°F (26.7°C) 32°F (0°C) 0°F (–17.8°C)

100 65 40

Figure 4-5 As temperature decreases, so does the power available from the battery.

The condition of the battery is critical for proper operation of the starting system and all other vehicle electrical systems. The battery is often overlooked during diagnosis of poor starting or no-start problems. Many problems encountered within the starting system may be attributed to poor battery condition. In addition, the proper battery selection for the vehicle is important. Some of the aspects that determine the battery rating required for a vehicle include engine size, engine type, climatic conditions, vehicle options, and so on. The requirements for electrical energy to crank the engine increase as the temperature decreases. Battery power drops drastically as temperatures drop below freezing (Figure 4-5). The engine also becomes harder to crank due to some oil’s tendencies to thicken when cold, resulting in increased friction. The battery’s ability to deliver power to crank the engine is described by the cold cranking amperage (CCA). A battery with a CCA rating of 600 is able to deliver 600 amperes of electrical current for 30 seconds when the battery is at 08F. A bigger engine will require a battery with a higher CCA than a small engine. The CCA requirement also increases in the northern regions of the continent, where temperatures regularly fall below freezing. The battery that is selected must also fit the battery-holding fixture, and the hold down must be able to be installed. It is also important that the height of the battery not allow the terminals to short across the vehicle hood when it is shut. Battery Council International (BCI) group numbers are used to indicate the physical size and other features of the battery. This group number does not indicate the current capacity of the battery. All batteries must be secured in the vehicle to prevent damage and the possibility of shorting across the terminals if the battery tips. Normal vibrations cause the plates to shed their active materials. Hold downs reduce the amount of vibration and help increase the life of the battery. The battery’s location may vary with different vehicles. Typically, the 12-volt battery is located under the hood and close to the front of the vehicle, in an area that is easy to get to for testing and replacement. Some vehicles may put the battery farther into the engine compartment, near the transaxle, in the trunk, or under the rear seat. These are known as remote location batteries (see Figure 4-6). There are many reasons for placing the battery

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Remote battery location

Figure 4-6 Some batteries are located remotely.

in these areas, which include weight distribution, temperature and insulation, and hood height and length. The batteries that are located inside the vehicle will have a vent tube that allows the battery to vent the gas during normal operation. It is important to refer to the manufacturer’s service manual if you cannot locate the battery.

The Starter Motor The armature is the movable component of the motor that consists of a conductor wound around a laminated iron core and is used to create a magnetic field. Pole shoes are made of high-magnetic permeability material to help concentrate and direct the lines of force in the field assembly.

Starter motors use the interaction of magnetic fields to convert electrical energy into mechanical energy. Figure 4-7 illustrates a simple electromagnet style of starter motor. The inside windings are called the armature. The armature rotates within the stationary outside windings, called the field, which has windings coiled around pole shoes. Some starters use stationary permanent magnets rather than the electromagnets created by the pole shoe windings. When current is applied to the field and the armature, both produce magnetic flux lines. The direction of the windings places the left pole at a south polarity and the right pole at a north polarity. The lines of force move from north to south in the field. In the armature, the flux lines circle in one direction on one side of the loop and in the opposite direction on the other side. Current now sets up a magnetic field around the loop of wire, interacting with the north and south fields and causing a turning force on the loop. This force causes the loop to turn in the direction of the weaker field (Figure 4-8).

Armature winding

Field winding

Pole shoe N

S Pole shoe Brush Spring ring commutator

Brush

Battery

Figure 4-7 Simple electromagnetic motor. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

S

65

N

Figure 4-8 Rotation of the conductor is in the direction of the weaker field.

Problems within the starter or in the wiring to the starter can prevent it from turning the engine over fast enough to start. Engine mechanical problems can also cause this symptom. You must evaluate the starting system before condemning the engine.

LUBRICATION SYSTEMS When the engine is operating, the moving parts generate heat due to friction. If this heat and friction were not controlled, the components would suffer severe damage and even weld together. In addition, heat is created from the combustion process. It is the function of the engine’s lubrication system to supply oil to the high-friction and high-wear locations and to dissipate heat away from them (Figure 4-9). It is impossible to eliminate all of the friction within an engine, but a properly operating lubrication system will work to reduce it. Lubrication systems provide an oil film to prevent moving parts from coming in direct contact with each other (Figure 4-10). Oil molecules work as small bearings rolling over each other to eliminate friction (Figure 4-11). Another function of the lubrication system is to act as a shock absorber between the connecting rod and the crankshaft. Besides reducing friction, engine oil absorbs heat and transfers it to another area for cooling. As the oil flows through the engine, it conducts heat from the parts it comes in contact with. When the oil is returned to the oil pan, it is cooled by the air passing over the pan. Other purposes of the oil include improving the seal between the piston rings and Camshafts

The engine’s lubrication system supplies oil to high friction and high wear locations.

Main oil gallery

Camshaft bearings Crankshaft bearings

Anti-drain back valve

Lash adjuster Oil pressure sending unit Connecting rod Oil filter

Spit hole

Oil pump

Oil pump Oil cooler

Pressure relief valve

Connecting rod journal

Filter Oil pickup

Figure 4-9 Oil flow diagram indicates the areas where oil is delivered by the lubrication system. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

66

Chapter 4 Most of slipping occurs near the center of oil film

Oil tends to resist movement on bearing and journal surfaces

Shaft

Stationary bearing

Figure 4-10 The oil develops a film to prevent metal-to-metal contact.

Moving components Oil molecules Stationary component

Figure 4-11 Oil molecules work as small bearings to reduce friction. An oil cooler is a heat exchanger that looks much like a small radiator.

the cylinder walls, and washing away abrasive metal and dirt. To perform these functions, the engine lubrication system includes the following components: ■ Engine oil ■ Oil pan or sump ■ Oil filter ■ Oil pump ■ Oil galleries ■ Oil coolers (heavy-duty applications)

Engine Oil Engine oil must provide a variety of functions under all of the extreme conditions of engine operation. To perform these tasks, additives are mixed with natural oil. A brief description of the types of additives used is as follows:

Oxidation occurs when hot engine oil combines with oxygen and forms carbon.

1. Antifoaming agents. These additives are included to prevent aeration of the oil. Aeration will result in the oil pump not providing sufficient lubrication to the parts and will cause low oil pressure. 2. Antioxidation agents. Heat and oil agitation result in oxidation. These additives work to prevent the buildup of varnish and to prevent the oil from breaking down into harmful substances that can damage engine bearings. 3. Detergents and dispersants. These are added to prevent deposit buildup resulting from carbon, metal particles, and dirt. Detergents break up larger deposits and prevent smaller ones from grouping together. A dispersant is added to prevent carbon particles from grouping together. 4. Viscosity index improver. As the oil increases in temperature, it has a tendency to thin out. These additives prevent oil thinning. 5. Pour point depressants. Prevent oil from becoming too thick to pour at low temperatures. 6. Corrosion and rust inhibitors. Displace water from the metal surfaces and neutralize acid.

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Engine Operating Systems

7. Cohesion agents. Maintain a film of oil in high-pressure points to prevent wear. Cohesion agents are deposited on the parts as the oil flows over them and remain on the parts as the oil is pressed out. Oil has traditionally been rated by two organizations: the Society of Automotive Engineers (SAE) and the American Petroleum Institute (API). The SAE has standardized oil viscosity ratings, while the API rates oil to classify its service or quality limits. Engine oil containers have markings on them indicating the qualities defined by these two organizations (Figure 4-12). The API and SAE ratings are written in the “doughnut” on oil containers (Figure 4-13). These rating systems were developed to allow proper selection of engine oil. Indicates use in spark ignition gas engine The latest revision of oil quality standards

American Petroleum Institute

M Society of Automotive Engineers

Cold viscosity, “W” stands for winter

Viscosity at normal engine operating temperature

Figure 4-12 Definition of the ratings shown on an oil container.

The API doughnut

Figure 4-13 The engine oil “doughnut” displays oil rating information such as the quality and viscosity of an oil. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

S-class oil is used for automotive gasoline engines. C-class oil is designed for commercial or diesel engines. The S stands for spark ignition, and the C stands for compression ignition. In some areas, the S stands for service engines, and the C stands for commercial engines.

The API classifies engine oils by a two-letter system. The prefix letter is either listed as S-class or C-class to classify the oil’s intended usage. S-class oil is designated for use in spark ignition engines; C-class oil should be used in compression ignition diesel engines. The second letter denotes various grades of oil within each classification and denotes the oil’s ability to meet the engine manufacturers’ warranty requirements. Each category of oil that meets the qualifications has been tested and approved by the API under set conditions. As new oil standards are developed, the next letter in the alphabet is used to designate the latest revision. As vehicles, engines, and driving habits continue to change, the oil formula must change along with it. This system began many years ago and has developed since then. The sequence started with an SA-approved oil. The SA oil is a plain mineral oil that doesn’t contain any additives. It was primarily used in the 1920s. Currently, the SN rating is used for all automotive engines in use. It provides improved oxidation resistance, improved deposit protection, better low-temperature performance, and better wear protection over the life of the oil. All newer API oils have a limitation on the amount of phosphorus that can be used. Phosphorus can be harmful to a catalytic converter. Newer engines are developed using the new oil standards. This means that you can use an SN grade oil in any vehicle, but you cannot use an SM or older oil in a newer vehicle that requires an SN grade oil. Diesel engine oils are much more complicated. The most current oil ratings for compression ignition engines are CJ-4, CI-4, CH-4, CG-4, CF-2, and CF. Some smaller stationary compression ignition engines (e.g., generators, pumps, and other commercial applications) use an older CC rating. The exhaust on these engines are regulated differently. Figure 4-14 charts the current production oil classifications for gasoline and diesel engines. The API intentionally omits the SI and SK from the sequence of categories. SA through SH are now obsolete. At present, many manufacturers of gasoline engines demand an SM or SN oil classification for warranty requirements. Most gasoline engine manufacturers also demand an engine oil with the API Starburst symbol displayed on the oil container (Figure 4-15). In addition to the SAE and API ratings, other ratings are common. The International Lubricant Standardization and Approval Committee (ILSAC) was formed to approve

0W16

Figure 4-14 SAE 0W-16, designed for greater fuel economy, came from the SAE 16 oil classification for oils having lower than 20 viscosity. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems API Categories Category

Service Recommendations

SN

Introduced in October 2010, the SN oil will work for all automotive gasoline engines currently in use.

SM

For use in 2010 and older automotive gasoline engines currently in use.

SL

For use in 2004 and older automotive gasoline engines currently in use.

SJ

For use in 2001 and older automotive gasoline engines currently in use.

CJ-4

Introduced in 2006, CJ-4 was designed to meet the requirements of 2007 model year on-highway exhaust emission standards.

CI-4

For use in high-speed, four-stroke diesel engines designed to meet the 2004 exhaust emission standards.

CH-4

For use in high-speed, four-stroke diesel engines designed to meet the 1998 exhaust emission standards.

CG-4

For use in severe-duty, high-speed, four-stroke diesel engines designed to meet the 1994 exhaust emission standards.

CF-4

For use in high-speed, four-stroke diesel engines designed to meet the 1990 exhaust emission standards.

CF-2

For use in severe-duty, two-stroke diesel engines.

CF

For use in off-road indirect-injected diesel engines, including those that use a 0.5% or greater sulfur content fuel.

AMERICA

PE

TROLEUM FOR

GASOLINE ENGINES

CE

TUTE STI IN

N

motor oils for use across domestic and import lines and to help speed up the certifying process. SAE, API, the Japanese Automobile Standards Organization (JASO) and DaimlerChrysler, General Motors, and Ford have all been involved in the development of the latest ILSAC standard oil GF-5 introduced late 2010. GF-4 oils are no longer available. Only oils with an SAE viscosity rating of 0W, 5W, or 10W may carry the GF rating. Other oil ratings that you may encounter include ACEA (common with European manufacturers) and JASO (Japanese Automotive Standards Organization). Some manufacturers have their own specific oil rating systems. One example of this is GM’s Dexos system. GM recommends the Dexos oil classification for its vehicles. According to GM it is designed to reduce emissions, provide for better fuel economy, last longer, and prolong the life of the emissions system. Many oil brands meet the Dexos specification. Dexos 1 is designed for gasoline engines, and Dexos 2 is designed for compression ignition engines. Different oils are being developed and tested for GDI systems because of soot accumulation in the oil.

RTIFIED

Figure 4-15 The API Starburst symbol is displayed on oil containers. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Viscosity is the measure of the resistance of the oil when placed under shear and extensional stress (the same stresses placed on oil by the crankshaft and connecting rod bearings). It is used to describe an oil’s internal resistance to flow. Technicians often use viscosity to describe an oil’s thickness or weight. All oils will break down their additives over time. Oil breakdown usually refers to the results from prolonged high temperatures and pressures that quickly degrade the oil and do not allow it to perform its duties. The viscosity index of an oil is a measure of the change in viscosity an oil will have with changes in temperature.

SAE ratings provide a numeric system of determining the oil’s viscosity. The higher the viscosity number, the thicker or heavier the weight of the oil. For example, oil classified as SAE 50 is thicker than SAE 20 oil. The thicker the oil, the slower it will pour. Thicker oils should be used when engine temperatures are high, but they can cause lubrication problems in cooler climates. Using an engine oil with a thicker viscosity than is recommended can cause premature engine wear. The thicker oil will not reach high-friction areas fast enough during the critical start-up and warm-up periods. Viscosity recommendations have become lighter over the years, as engine machining improvements produce engines with closer clearances. The thinner oils are needed to circulate between the closefitting components. Thinner oils will flow through the engine faster and easier at colder temperatures, but oil breakdown may occur under higher temperatures or heavy engine loads. Oil also has to be thick enough to seal piston rings, yet if it is too thin, the engine will not develop enough oil pressure. The oil viscosity will also change with temperature. The higher the temperature, the lower the viscosity, and vice versa. A compromise is needed. Multigrade oils were developed for this reason. Multigrade oils contain two viscosities and are designated by their label. For example, an SAE 5W30 oil is a multigrade oil. The W stands for winter. SAE has established a standard for testing these oils. The lower number (5 in this case) is the viscosity of the oil at 08C , and the higher number (30 in this case) is the viscosity of the oil at 1008C (328F and 2128F, respectively). The manufacturing of multigrade oil starts out with a base oil. This base oil is typically the lower number (5 in our case). Viscosity index modifiers are then added to change the viscosity of the oil by changing its behavior at higher temperatures. A single-grade oil is different than a multigrade oil because it cannot pass the low temperature SAE standard. Oils have been developed that may be labeled “energy conserving.” These oils use friction modifiers to reduce friction and increase fuel economy. The energy-conserving designation is displayed in the lower portion of the “doughnut.” Selection of oil is based upon the type of engine and the conditions it will be running in. The API ratings must meet the requirements of the engine and provide protection under the normal expected running conditions. One consideration in selecting SAE ratings is ambient temperatures. Some manufacturers will recommend an oil viscosity rating for normal driving and suggest thicker oil while driving at high sustained speeds in a hot climate. A motorist may request that you refill the engine with higher-viscosity oil before a summer vacation while pulling a camper, for example. Many consumers run the standard oil in the vehicle year-round. Always select oil that meets or exceeds the manufacturer’s recommendations. To a great degree it is the improvement in the quality of oils that has allowed the tighter clearances and improvements in piston fit and ring selection. The incredible gains in oil technology are a significant part of the reason that engines now often last 150,000 miles or longer before needing major service. Use a high-quality oil with the viscosity rating specified by the manufacturer, and change it regularly to get the most life out of an engine. SL, GF-4 oil is able to meet the extreme demands of late-model, precisely machined engines.

Synthetic Oils Synthetic oils are oils primarily composed of chemical compounds that are synthetically made in a laboratory. Synthetic oils are manufactured as a substitute for and generally provide superior properties when compared to conventional petroleum oils. Most synthetic oil ratings not only meet but exceed the API and ILSAC ratings for their given SAE viscosity. Synthetic engine oils have been in use for a long time, but it hasn’t been until recently that their use as an automotive engine oil has been widely accepted. Synthetic oils are chemically more stable, have extended oil change intervals, have better viscosity performance at extreme temperatures, increase fuel mileage, provide better lubrication on cold starts, and are very resistive to oil breakdown, sludge, and oxidation. In some cases, using synthetic engine oils are a part of the initial engine designs to help lower emissions. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

Today’s modern engines are built to provide more power from a smaller engine. Engine compartments are typically smaller and have less wind movement and heat dissipation than the previous older, larger vehicles. Combustion chamber temperatures are typically higher as well. For these reasons, all modern engines are under more stress to perform. Overall, engine temperatures are warmer, and if the cooling system is neglected, they are more susceptible to overheating and damage. In a modern engine, one of the major problems with oil is sludge buildup. Oil sludge buildup is when the oil gels or solidifies after it has been broken down due to high stresses in the engine. Oil sludge is a preventable disaster. Regular maintenance and inspections can prevent major buildup. When oil additives break down the oil, it oxidizes (mixes with oxygen) and begins to gel. When the oil gels, it flows slower and sticks to the walls of the oil galleries. Often, this gel will stick to oil return galleries and cause low oil levels in the oil sump. This, of course, leads to oil starvation and engine damage. Oil sludge problems, emissions standards, fuel mileage standards, and customer demand have led many manufacturers to install synthetic oils in brand new vehicles. Manufacturers that choose to add synthetic oils to their vehicles may even suggest that synthetic oil continue to be used during regular oil changes. The manufacturers of these vehicles are also using synthetic engine oils because of their superior qualities to regular oil. If a customer already has synthetic engine oil in his or her engine from the factory, it is recommended to continue to use synthetic oil. Synthetic oils do not gel as much as traditional oils do in colder temperatures. An engine may start easier and fully lubricate faster in extreme cold temperatures with synthetic oils. Synthetic oils are mainly used for their superior engine protection, especially during cold starts when most engine damage occurs. Synthetic oils also have more stability over time, better lubricity, and better resistance to thermal breakdown. Some customers claim increased fuel mileage, but the increase in mileage by just changing the type of oil alone is very small and difficult to measure. If customers want to switch to synthetic oil during a routine oil change, try to advise them with the knowledge you have and the written material the synthetic oil manufacturer provides. Also check with the manufacturer’s service literature and technical service bulletins for information about the warranty. Most warranties are not voided when using synthetic oils at recommended intervals, but you should still check. Synthetic oils can be used in gas or diesel engines. Some engine rebuilders do not recommend using synthetic oils during the engine break-in period (typically the first 500 miles after a rebuild). Other sources may point to the fact that some new vehicles are using synthetic oils as a factory fill. New engines from the manufacturer are machined to a lower tolerance than most rebuilt engines and are manufactured in very controlled environments. The decision to use a synthetic oil during engine break-in should be made after considering the extent of the rebuild, the type, and the quality of any machining performed, and the type and quality of the parts that were installed.

Oil Pumps The oil pump is the heart of the lubrication system. It develops oil pressure to pump oil throughout the engine. There are two basic types of oil pumps: rotor and gear. Both types are positive displacement pumps. The rotary pump generally has a four-lobe inner rotor with a five-lobe outer rotor (Figure 4-16). The outer rotor is driven by the inner rotor. As the lobes come out of mesh, a vacuum is created, and atmospheric pressure on the oil pushes it into the pickup tube. The oil is trapped between the lobes as it is directed to the outlet. As the lobes come back into mesh, the oil is expelled under pressure from the pump. Gear pumps can use two gears riding in mesh with each other or use two gears and a crescent design (Figure 4-17). Both types operate in the same manner as the rotor-type pump. The advantage of the rotor-type pump is its capability to deliver a greater volume of oil since the cavities are larger.

71

Oil sludge buildup occurs when the oil gels and thickens due to oxidizing.

The oil pump creates a vacuum so atmospheric pressures can push oil from the sump. The pump then pressurizes the oil and delivers it throughout the engine by use of galleries. Positive displacement pumps deliver the same amount of oil with every revolution, regardless of speed.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4 Outer rotor

Oil Inner rotor

Oil

Inlet

Outlet

Pump gears

Figure 4-16 Typical rotor-type oil pump.

Figure 4-17 Typical gear-type oil pump.

Oil Pump

Figure 4-18 This crankshaft-driven oil pump sits under the timing cover.

Many of today’s engines drive the oil pump by the front of the crankshaft (Figure 4-18). In the past, most oil pumps were driven off of the camshaft by a drive shaft fitting into the bottom of the distributor shaft, but not many engines still use an ignition distributor (Figure 4-19). Most lubrication systems use oil pressures between 10 and 80 psi, depending on engine speed and temperature. A general rule of thumb is that an engine should develop a minimum of 10 psi of oil pressure for each 1,000 rpm of engine speed once the engine is at operating temperature. Since oil pumps are positive displacement types, output pressures must be regulated to prevent excessive pressure buildup. A pressure relief valve opens to return oil to the sump or pump inlet if the specified pressure is exceeded (Figure 4-20). A calibrated spring holds the valve closed, allowing pressure to increase. Once the oil pressure is great enough to overcome the spring pressure, the valve opens and returns the oil to the sump or pump inlet.

Oil Filter As the oil flows through the engine, it works to clean dirt and deposits from the internal parts. These contaminants are deposited into the oil pan or sump with the oil. Since the oil pump pickup tube syphons the oil from the sump, it can also pick up these contaminants. The pickup tube has a screen mesh to prevent larger contaminants from being picked up Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems Camshaft

Oil relief valve

73

Main oil gallery

Spring Distributor gear

Drive shaft

Mechanical-style fuel pump

Oil pump

Oil overflow return to pan

Figure 4-20 The oil pressure relief valve opens to return the oil to the sump if oil pressures are excessive.

Figure 4-19 Some oil pumps are driven by a gear on the camshaft.

and sent back into the engine. The finer contaminants must be filtered from the oil to prevent them from being sent with the oil through the engine. Oil filter elements have a pleated paper or fibrous material designed to filter out particles between 20 and 30 microns (Figure 4-21). Most oil filters use a full-filtration system. Under pressure from the pump, oil enters the filter on the outer areas of the element and works its way toward the center. In the event the filter becomes plugged, a bypass valve will open and allow the oil to enter the oil galleries. If this occurs, the oil will no longer be filtered (Figure 4-22).

A micron is a thousandth of a millimeter or about 0.0008 inch. A full-filtration system means all of the oil is filtered before it enters the oil galleries.

Inlet check valve Inlet check valve

Filter element

Bypass valve open Bypass valve

Figure 4-21 Oil flow through the oil filter.

Figure 4-22 If the oil filter becomes plugged, the bypass valve opens to protect the engine.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

The inlet check valve keeps the oil filter filled at all times, so when the engine is started, an instantaneous supply of oil is available.

An oil cooler is a heat exchanger that looks much like a small radiator.

An inlet check valve is used to prevent oil draining back from the oil pump when the engine is shut off. The check valve is a rubber flap covering the inside of the inlet holes. When the engine is started and the pump begins to operate, the valve opens and allows oil to flow to the filter.

Oil Coolers Turbocharged, supercharged, and other high-performance engines or engines in vehicles designed to haul or tow frequently use an oil cooler to help keep oil temperatures at a safe level. Oil temperature should generally run between 2008F and 2508F. Excess heat will prematurely break down the oil and allow premature engine wear. Oil coolers look like small radiators and are usually mounted near the radiator. Some designs exchange their heat with cooler incoming air, similar to how a radiator works. Others use engine coolant to remove the heat. Some manufacturers have the oil filter located remotely (not directly mounted on the engine). This also acts like a small oil cooler because cooler air will flow over hoses and the filter.

Oil Flow The saddle is the portion of the crankcase bore that holds the bearing half in place. Jet valves are used to help cool pistons.

The connecting rod journal is also referred to as the crank pin.

The oil pump sends pressurized oil to the oil filter. After the oil leaves the filter, it is directed through galleries to various parts of the engine. A main oil gallery is usually drilled through the length of the block. From the main gallery, pressurized oil branches off to upper and lower portions of the engine (Figure 4-23). Oil is directed to the crankshaft main bearings through the main bearing saddles. Passages drilled in the crankshaft then direct the oil to the rod bearings (Figure 4-24). Some manufacturers drill a small spit or squirt hole in the connecting rod to spray pressurized oil delivered to the bearings out and onto the cylinder walls (Figure 4-25). When the spit hole aligns with the oil passage in the rod journal, it squirts the oil onto the cylinder wall. Some engines use jet valves to spray oil into the underside of the piston to cool it (Figure 4-26). Each camshaft bearing (on OHV engines) also receives oil from passages drilled in the block (Figure 4-26). The valvetrain can receive oil through passages drilled in the

A BIT OF HISTORY Ernest Sweetland and George H. Greenhalgh patented the first oil filter in 1923. It was a device that was designed to trap particles in the oil and allow clean oil to pass through. Their patent was named “Purolator,” which was short for “pure oil later.” You can find Purolator oil filters still sold today.

Figure 4-23 Some oil filters do not have a housing around the filter media. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

75

block and then through a hollow rocker-arm shaft. Engines using pushrods usually pump oil from the lifters through the pushrods to the valvetrain (Figure 4-27). Oil sent to the cylinder head is returned to the sump through drain passages cast into the head and block. Oil passages

Drive belt end

Flywheel end Counterweights

Oil passages

Figure 4-24 Oil passages drilled into the crankshaft provide lubrication to the main bearings.

Squirt hole

Connecting rod

Piston Cam bearing Crank bearing

Figure 4-26 OHV engines have branches from the main oil gallery to direct pressurized oil to the camshaft journals.

Figure 4-25 A squirt hole is used to lubricate the cylinder walls and remove excess heat from the piston head.

Pushrod

Lifter

Camshaft

Oil return

Figure 4-27 OHV engines often use hollow pushrods to deliver oil pressure to the cylinder head and valvetrain. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Not all areas of the engine are lubricated by pressurized oil. The crankshaft rotates in the oil sump, creating some splash-and-throw effects. Oil that is picked up in this manner is thrown throughout the crankcase. This oil splashes onto the cylinder walls below the pistons. This provides lubrication and cooling to the piston pin and piston rings. In addition, oil that is forced out of the connecting rod bearings is thrown to lubricate parts that are not fed pressurized oil. Valve timing chains are often lubricated by oil draining from the cylinder head being dumped onto the chain and gears.

AUTHOR’S NOTE During my experience as an automotive technician and instructor, I encountered a significant number of vehicle owners who attempted to save money on car maintenance by extending engine oil and filter changes beyond the manufacturer’s recommended interval. Unfortunately, they spent a lot more on premature and expensive engine repairs than they saved on maintenance costs. Proper lubrication system maintenance is extremely important to provide long engine life; explain this to your customers. In some cases, the engine damage will cause excessive exhaust emissions. A vehicle with this situation will likely not pass the required emissions testing found in some states and regions of the United States.

COOLING SYSTEMS A cooling system controls the temperature of an engine by allowing it to heat up quickly, operate at the correct temperature, and remove excess heat.

The heat created during the combustion process could quickly increase to a point where engine damage would occur. The cooling system is used to disperse the heat to the atmosphere. The cooling system also allows the engine to warm up quickly and provides an even operating temperature. This is important for minimizing emissions and providing efficient engine operation. The cooling system also provides heat for the passenger compartment. The components of the cooling system include the following: ■ Coolant ■ Radiator ■ Radiator cap ■ Recovery system ■ Coolant jackets ■ Hoses ■ Water pump ■ Thermostat ■ Cooling fan ■ Heater system ■ Transmission cooler ■ Temperature warning system

Coolant Electrolysis is the chemical and electrical process of decomposition that occurs when two dissimilar metals are joined with the presence of moisture. The lesser of the two metals is eaten away.

Water by itself does not provide the proper characteristics needed to protect an engine. It works quite well to transfer heat, but does not protect the engine in colder climates. The boiling point of water is 2128F (1008C), and it freezes at 328F (08C). Temperatures around the cylinders and in the cylinder head can reach above 5008F (2508C), and the engine will often be exposed to ambient temperatures below 328F (08C). In addition, water reacts with metals to produce rust, corrosion, and electrolysis. Coolant must protect against freezing, reduce rust and corrosion in the cooling system, and lubricate the water pump and seals. Most manufacturers use a glycol-based engine coolant. In older engines, there was only

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

one type of coolant. Today there are several types of coolants and many different applications for each. Traditional green ethylene glycol (EG) coolant has been used for many years. It uses inorganic borate salts, silicate, and phosphate to minimize rust and corrosion. These additives break down over time, and the coolant becomes acidic. The acidity accelerates corrosion. The newer extended-life, EG-based coolants have a different additive package designed to lengthen the effective life of the coolant. These coolants use a new type of corrosion inhibitor called Organic Additive Technology (OAT) corrosion inhibitors. Many manufacturers using extended-life coolant now specify flushing the cooling system every 5–10 years or 100,000–150,000 miles rather than the traditional coolant flush recommendation of two years or 30,000 miles. Many European manufacturers specify coolants with no phosphates to reduce sediment and scale buildup when mixed with hard water. Asian manufacturers may specify a coolant with little or no silicates. These different coolants may be blue, pink, yellow, orange, or red. Propylene glycol (PG) coolant is manufactured because it is less toxic than EG coolant. Less than half a cup of EG coolant is potentially fatal to pets and humans. Animals are attracted to coolant because it is sweet. Some consumers may choose to fill their cooling systems with these environmentally friendly coolants. If EG and PG are mixed, it is more difficult to detect the antifreeze protection level. Propylene glycol is not recommended by any vehicle manufacturers and, if used, could possibly void the vehicle’s warranty. Each manufacturer installs its own type of coolant from the factory for specific reasons. Different types and brands of coolant protect engine parts in different ways. Since each manufacturer uses different types and blends of metals, runs different temperatures, and uses different computer programs to control the engine and the emissions, it is important to recognize that you should be using the type of coolant that is recommended by the manufacturer. Not surprisingly, cooling system failures are the leading cause of other mechanical breakdowns. One of the most common problems related to coolant degradation is electrolysis. When two or more dissimilar metals are used in the parts of the engine that touch the coolant, a small electrical charge will occur. This electrical charge is similar to the electrical charge produced by the vehicle’s lead acid battery. A battery uses two different metal plates to create and hold its charge. An engine is similar in that some parts are aluminum, iron, copper, or brass. Electrolysis can damage the cooling system walls and make them thinner. Having the proper coolant in the engine protects the metals in the engine and cooling-heating system from electrolysis damage. Excessive electrolysis can lead to overheating, leaking, seal damage, hose damage, and gasket damage. In some cases, it will make component removal difficult. Air should not be trapped in the coolant. If air is trapped in the coolant, the engine may not cool properly, and the heater system may not heat properly. Air may get into the system for several reasons: component replacement, coolant leakage, or improper refill. Air pockets can explode in the coolant and cause metal cavitation. Trapped air can also cause the coolant to become acidic. It is important to keep the system bled properly. Some vehicles have a coolant bleed screw to remove the air from the system, while others may need special tools or procedures to remove the air. Removing the air from the cooling system is covered in the Shop Manual. Use the proper coolant and water mixture to protect the engine under most conditions. Water expands as it freezes. If the coolant in the engine block freezes, the expansion could cause the block or cylinder head to crack. If the coolant boils, liquid is no longer in contact with the cylinder walls and combustion chamber. The vapors are not capable of removing the heat, and the pistons may collapse, or the head may warp or crack from the excessive heat. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Nucleate boiling is the process of maintaining the overall temperature of a coolant to a level below its boiling point, but allowing the portions of the coolant actually contacting the surfaces (the nuclei) to boil into a gas. The radiator is a heat exchanger used to transfer heat from the engine to the air passing through it.

For every pound of pressure increase, boiling point of water is raised about 3 1 4 8F.

Radiator The radiator contains a series of tubes and fins that transfer the heat in the coolant to the air. As the coolant is circulated throughout the engine, it attracts and absorbs the heat within the engine, and then flows into the radiator intake tank. The coolant then flows 40 30

236

20

234

10

232

0

230

−10

228

−20

226

−30

224

Freezing −40

222

−50

220

−60

Boiling point °F, 0 PSIG

Freezing point °F, 0 PSIG

Many vehicles that experience difficulty with air entering the cooling system during service add a bleeder valve at the high point of the cooling system to allow the technician to bleed the system of air.

Ethylene glycol by itself has a boiling point of 3308F (1658C), but it does not transfer heat very well. The freezing point of EG is 88F (2138C). To improve the transfer of heat and lower the freezing point, water is added in a mix of about 50/50. At a 50/50 mix, the boiling point is 2268F (1088C), and the freezing point is 348F (18C). In some very cold climates, coolant is mixed with water in a 60/40 ratio to prevent freezing to at least 408F. These characteristics can be altered by changing the mixture (Figure 4-28). It may appear that lowering the boiling point by adding water is not desirable. In fact, this is required for proper engine cooling. Under pressure, the boiling point of the coolant mix is about 2638F (1288C). As was stated earlier, the temperature next to the cylinder or cylinder head may be in excess of 5008F (2608C). As coolant droplets touch the metal walls, they boil and are turned into a gas. The superheated gas bubbles are quickly carried away into the middle of the coolant flow, where they cool and condense back into a liquid. If this nucleate boiling did not occur, the coolant would not be capable of removing heat fast enough to protect the engine. Over time, all coolant can become slightly acidic because of the metals and minerals in the cooling system. All vehicle manufacturers provide a maintenance schedule recommending cooling system flushing and refill based on time and mileage.

218

Boiling −70

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−80

214

−90

212

−100 0

10

20

30

40

50

60

70

80

90

100

Antifreeze/coolant

Figure 4-28 Changing the strength of the coolant mixture affects its boiling and freezing points. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems

through the tubes to the outlet tank. As the heated coolant flows through the radiator tubes, the heat is dissipated into the air through the fins. There are two basic radiator designs: downflow and crossflow. Downflow radiators have vertical fins that direct coolant flow from the top inlet tank to the bottom outlet tank (Figure 4-29). Crossflow radiators use horizontal fins to direct coolant flow across the core (Figure 4-30). The core of the radiator can be constructed using a tube-and-fin or a cellular-type design (Figure 4-31). The material used for the core is usually copper, brass, or aluminum. Aluminum-core radiators generally use nylon-constructed tanks. For heat to be transferred to the air effectively, there must be a significant difference in temperature between the coolant and the air. The greater the temperature difference, the more effectively heat is transferred. Manufacturers increase the temperature and boiling Top tank Inlet from engine Filler cap

Cooling fins (horizontal)

Core tubes

Transmission oil cooler Bottom tank

Figure 4-29 A typical downflow radiator.

Filler cap

Outlet tank

Inlet tank

Inlet

Overflow

Cooler fittings (optional)

Drain Outlet Cooling fins (vertical)

Core tube

Figure 4-30 A typical crossflow radiator. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4 Water passage tubes

Water passage tubes Top header

Top header

(A)

(B)

Figure 4-31 (A) Construction of a cellular radiator core. (B) Construction of a tube and fin radiator.

point of the coolant by pressurizing the radiator. The radiator cap allows for an increase of pressure within the cooling system, increasing the boiling point of the coolant; for example, if the pressure is increased to 15 psi (103 kPa), the boiling point of the 50/50 mix would be increased to 2668F (1308C). Because the boiling point is increased, the operating temperature of the engine can also be increased.

A BIT OF HISTORY In the early years of the automobile, water was used as engine coolant. This is where some of the engine parts got their name, like the water pump. The water worked well to remove heat from the engines, but it would freeze, resulting in cracked blocks. Motorists used several different substances to prevent the water from freezing. Most of these substances prevented freezing but had other adverse effects to the engine. Some of these early substances included salt, calcium chloride, soda, sugar, honey, engine oil, and coal oil. The first successful antifreeze was made from wood or grain alcohol. However, these substances lowered the boiling point of the water and evaporated at higher engine temperatures. The first permanent antifreeze (meaning it would not evaporate) was made with a glycerin base.

The coolant recovery system prevents loss of coolant if the engine overheats, and it keeps air from entering the system.

The radiator cap uses a pressure valve to pressurize the radiator to between 14 and 18 pounds per square inch (Figure 4-32). If the pressure increases over the setting of the cap, the cap’s seal will lift against a spring and release the pressure into a recovery tank (Figure 4-33). The cap also has a vacuum valve that will release any vacuum from the system as the coolant temperature decreases after the engine is turned off. If a vacuum is developed in the cooling system, the radiator could collapse. The coolant recovery system contains a reservoir that is connected to the radiator by a small hose. The coolant expelled from the radiator during a high-pressure condition is sent to this reservoir. When the engine cools, a void is created in the radiator, and the vacuum valve in the radiator cap opens (Figure 4-34). Under this condition, atmospheric pressure on the coolant in the overflow reservoir pushes it back into the radiator. Due to lower hood lines, many vehicles now use a remote pressure tank. There is no cap on the radiator; the system is filled and checked at the remote pressure tank, sometimes called the reservoir. These are used because the top of the radiator is lower than the highest point on the cooling system. During filling, the system would collect air pockets in the higher spots of the engine cooling systems. These reservoirs are not the same as coolant recovery tanks; they contain coolant under pressure, and the top should never be removed while the coolant is hot.

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Figure 4-32 The radiator cap seals the radiator or reservoir and regulates system pressure. Radiator pressure cap Spring

Rubber seal

Full hot

Full cold

Radiator tank

To recovery tank

Coolant recovery tank

Figure 4-33 A typical coolant recovery system holds coolant released from the radiator.

Vacuum relief

Figure 4-34 When the radiator cap vacuum valve opens, coolant from the recovery reservoir enters the radiator.

Whenever an engine is rebuilt, the radiator should be thoroughly cleaned and then inspected by pressure testing it. The radiator cap should be replaced with a new one.

Heater Core The heater core is similar to a small version of the radiator. The heater core is located in a housing, usually in the passenger compartment of the vehicle (Figure 4-35). Some of the hot engine coolant is routed to the heater core by hoses. The heat is dispersed to the air inside the vehicle, thus warming the passenger compartment. To aid in quicker heating of the compartment, a heater fan blows the radiated heat into the compartment.

The heater core dissipates heat like a radiator. The radiated heat is used to warm the passenger compartment.

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Heater core

Figure 4-35 The heater core is shown in this cutaway of a heater distribution box.

Hoses Hoses are used to direct the coolant from the engine into the radiator and back to the engine. In addition, hoses are used to direct coolant from the engine into the heater core and (on some engines) to bypass the thermostat. Since radiator and heater hoses deteriorate from the inside out, most manufacturers recommend periodic replacement of the hoses as preventive maintenance. Whenever the engine is rebuilt, the hoses should always be replaced. It is true that newer and higherquality hoses are built to last longer and stand up better to electrolysis degradation.

Water Pump The water pump is the heart of the engine’s cooling system. It forces the coolant through the engine block and into the radiator and heater core (Figure 4-36). The water pump is driven by an accessory belt, by the timing belt, or directly from the camshaft. Some hybrids drive the water pump using an electric motor. Most water pumps have a centrifugal design, using a rotating impeller to move the coolant (Figure 4-37). When the engine is running, the impeller rotates, forcing coolant from the inside of the cavity outward toward the tips by centrifugal force. Once inside the block, the coolant flows around the cylinders and into the cylinder heads, absorbing the heat from these components. If the thermostat is open, the coolant will then enter the radiator. The void created by the empty impeller cavity allows the pressurized coolant to be pushed from the radiator to fill the cavity and repeat the cycle. When the thermostat is closed because coolant temperatures are too cold, the coolant is circulated through a bypass. This keeps the coolant circling through the engine block until it gets warm enough to open the thermostat.

Thermostat The thermostat allows the engine to quickly reach normal operating temperatures and maintains the desired temperature.

Control of engine temperature is the function of the thermostat (Figure 4-38). The thermostat is usually located at the outlet passage from the engine block to the radiator. When the coolant is below normal operating temperatures, the thermostat is closed, preventing coolant from entering the radiator. In this case, the coolant flows through a bypass passage and returns directly to the water pump (Figure 4-39). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems Radiator cap

Overflow recovery tank

Radiator hose Thermostat

Heater control

Heater core

AIR FLOW Heater hoses

Radiator Water pump

Water jacket

Combustion chamber

Figure 4-36 Coolant flow through the engine.

Body

Fan hub Seal

Impeller

Bearing and shaft assembly Drain

Figure 4-37 Most water pumps use an impeller to move coolant through the system. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-38 The thermostat controls the temperature of the coolant.

Thermostat housing

Bypass hose

Water pump Fan hub

Figure 4-39 The bypass hose lets coolant return to the water pump.

The thermostat is rated at the temperature it opens in degrees Fahrenheit. If the rating is 1958F , this is the temperature at which the thermostat begins to open. When the temperature exceeds the rating of the thermostat by 208F, the thermostat will be totally open. Once the thermostat is open, it allows the coolant to enter the radiator to be cooled. The thermostat cycles open and closed to maintain proper engine temperature. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems This end toward radiator

Vent closed

Piston

85

Piston

Vent open

Wax pellet Coolant flow restricted Wax pellet Case end rests in coolant

Coolant flow Rubber

Figure 4-40 The temperature-sensitive wax pellet controls the valve in the thermostat.

Case and valve assembly are forced down, causing the valve to open

Rubber is compressed

Figure 4-41 When the pellet expands, the thermostat opens and allows the coolant to flow through the radiator.

Operation of the thermostat is performed by a specially formulated wax and powdered metal pellet located in a heat-conducting copper cup (Figure 4-40). When the wax pellet is exposed to heat, it begins to expand. This causes the piston to move outward, opening the valve (Figure 4-41). Thermostats have a high failure rate and are a very common cause of cooling system concerns. Do not install a thermostat with a lower opening temperature or run the engine without a thermostat. Allowing the engine to run cooler than designed accelerates engine wear and increases emissions and fuel consumption.

Coolant Flow Coolant flow through the engine can be one of two ways: parallel or series. In a parallel flow system, the coolant flows into the engine block and into the cylinder head through passages beside each cylinder. In a series flow system, the coolant enters the engine block and flows around each cylinder (Figure 4-42). It then flows to the rear of the block and through passages to the cylinder head (Figure 4-43). The coolant then flows through the head to the front of the engine (usually the highest point of the cooling system) and out to the radiator.

Top hose

Cylinder heads

Radiator

Lower hose

Figure 4-42 The parallel flow sends the coolant around each cylinder and up to the cylinder head. There is more than one path for coolant to flow to the head. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4 Upper radiator hose Cylinder head

Lower radiator hose

Water jackets in engine block

Figure 4-43 A series flow directs the coolant around all of the cylinders before sending it up through the cylinder head.

The head gasket is used to prevent compression pressures, gases, and fluids from leaking. It is located on the connection between the cylinder head and engine block.

The cooling system passages are more than hollow portions in a casting. They are designed and located so no steam pockets can develop. Any steam will go to the top of the radiator. This is accomplished by bleed holes among the cylinder block, head gasket, and cylinder head. Corrosion or contaminants can plug the coolant passages. This results in reduced heat transfer from the cylinder to the coolant. Deposits can build up in small corners around the valve seats, causing hot spots in the cylinder head. This can allow the cylinder head to crack or the valves to burn.

Reverse-Flow Cooling Systems In a reverse-flow cooling system, coolant flows from the water pump through the cylinder heads and then through the engine block.

A reverse-flow cooling system was used in some engines, such as the General Motors LT1 5.7 L V8 engine in some model years of Camaro, Firebird, and Corvette. In these engines, the water pump forces coolant through the cylinder heads first and then through the block passages (Figure 4-44). The water pump is driven from a gear and shaft mounted on the front of the engine. The water pump drive gear is rotated by gear teeth on the back of the camshaft sprocket (Figure 4-45). Coolant flows from the block through other water pump passages and through the upper radiator hose to the radiator. Coolant returns through the lower radiator hose to the inlet side of the water pump. On a conventional flow cooling system, the coolant flows through the block first and then through the cylinder heads. When the engine is running, the hottest part is the exhaust valve seat. Circulating coolant through the cylinder head first means that the exhaust valve seats (and the entire cylinder head) will operate at cooler temperatures because they have cooler coolant flowing through them versus warmer coolant that picked up the heat from the cylinder block. This allows the combustion chamber to operate at a higher temperature. The higher temperature is a result of a higher compression ratio. The compression ratio in the LT1 engine is 10.25:1. Improved combustion chamber cooling also allows the engine to operate with increased spark advance without encountering detonation problems. This action improves fuel economy and engine performance.

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Engine Operating Systems

Many manufacturers now have systems in which the coolant leaves the radiator through the top radiator hose and then enters the engine through the intake manifold or head. It then passes through the head or heads and engine block to the thermostat located in or near the lower radiator hose. As the coolant heats up, the thermostat opens, allowing the hot coolant back into the lower end of the radiator to release its heat.

Radiator vent

Hi-fill reservoir Heater core

Thermostat

Cylinder head

Engine block

Figure 4-44 Reverse-flow cooling system.

Figure 4-45 Water pump drive. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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COOLING FANS To increase the efficiency of the cooling system, a fan is mounted to direct flow of air through the radiator core or past the radiator tubes. In the past, at high vehicle speeds airflow through the grill and past the radiator core was sufficient to remove the heat. The cooling fan was really only needed for low-speed conditions when airflow was reduced. As modern cars have become more aerodynamic, airflow through the grill has declined; thus proper operation of the cooling fan has become more critical. The cooling fan can be driven either mechanically by the engine or by an electric motor. Electric drive fans are common on today’s vehicles because they operate only when needed, thus reducing engine loads. Some of the earlier designs of electric cooling fans use a temperature switch in the radiator or engine block that closes when the temperature of the coolant reaches a predetermined value. With the switch closed, the electrical circuit is completed for the fan motor relay control circuit and the fan turns on (Figure 4-46). The power feed to the relay is supplied through the ignition switch or directly from the battery. If it is supplied directly from the battery, the cooling fans can come on, even though the engine is not running. Now, most cooling fans are controlled by the powertrain control module (PCM). The PCM receives engine coolant temperature input signals from the thermistor-type engine coolant temperature (ECT) sensor. When the ECT sensor indicates that the temperature is hot enough to turn on the fans, usually around 2008F–2308F, the PCM activates the fan control relay (Figure 4-47). In this diagram, the relay has power from the fuse waiting at pins number 2 and number 3. When the PCM decides to turn the fan on, it provides a ground to pin number 1 of the relay. This allows current to flow from the 10-amp fuse, through pin number 2 and the relay coil, and to ground through the PCM. Current flowing through the coil inside the relay creates a magnetic field that pulls the contacts between pins number 3 and number 4 closed. Now power can flow from the 40-amp fuse, to pin number 3 and through the closed relay contact points, out through pin number 4 and to the cooling fan. The cooling fan already has a ground supply, so it begins to spin. On some vehicles, the PCM also turns on the fans whenever air-conditioning is turned on, regardless of the engine temperature. In some cases, the electric cooling fan may turn on because the engine is hot, even if the ignition is off and the key is out. Belt-driven fans usually attach to the water pump pulley (Figure 4-48). Some beltdriven fans use a viscous-drive fan clutch to enhance performance (Figure 4-49). The clutch operates the fan in relation to the engine temperature using silicone oil (Figure 4-50). If the engine is hot, the silicone oil in the clutch expands and locks the fan to the pump hub. The fan now rotates at the same speed as the water pump. When the engine is cold, the silicone oil contracts and the fan rotates at a reduced speed. Some fan clutches Fan control relay

Temperature sensor switch

Battery

Jumper wire

Fan motor

Figure 4-46 Simplified electric fan circuit. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Operating Systems Hot in run

89

Hot at all times

Fuse block

Fan/TCC 10 a

Maxi 40 a

Low-speed fan relay 3

2

1

Right side cooling fan

4

High-speed fan relay 3

2

1

LH maxifuse center

Left side cooling fan

4

Fan 2 (high)

Fan 1 (low)

5V

PCM A/C pressure signal Engine 5V coolant Temperature signal

T

Figure 4-47 The PCM looks at the ECT and A/C inputs to decide when to turn the fans on.

Water pump pulley Water pump pulley spacer

Fan attachment bolt Fan Engine-cooling fan assembly

Figure 4-48 Belt-driven cooling fans are usually mounted to the water pump pulley.

Clutch

Figure 4-49 Most mechanical fans use a clutch to minimize noise and load on the engine when the engine is cooler.

use a thermostatic coil that winds and unwinds in response to the engine temperatures (Figure 4-51). The coil operates a valve that prevents or allows silicone to leave the reservoir and flow into the working chamber. Some performance engines use a clutch fan that is electronically operated (Figure 4-52). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4 Working chamber

Silicone oil Shaft

Clutch plate

Fan hub

Figure 4-50 The viscous-drive clutch uses silicone oil to lock the fan to the hub.

Figure 4-51 As temperature increases, the bimetallic spring expands to operate the clutch and lock the fan on.

Figure 4-52 This clutch fan is electronically controlled by the PCM.

LUBRICATION AND COOLING WARNING SYSTEMS AND INDICATORS Vehicle manufacturers provide some method of indicating problems with the lubrication or cooling system to the driver. This is done by the use of an indicating gauge or by the illumination of a light. Some manufacturers control the operation of the gauge or light by computers. Regardless of the type of control, sensors or switches provide the needed input. The thermistor is a resistor whose resistance changes in relation to changes in temperature. It is often used as a coolant temperature sensor.

Gauge Sending Units The most common sensor type used for monitoring the cooling system is a thermistor. The lubrication system uses piezoresistive sensors to measure oil pressure. In a simple coolant temperature-sensing circuit, current is sent from the gauge unit into the top terminal of the sending unit, through the variable resistor (thermistor), and to the engine block (ground). The resistance value of the thermistor changes in proportion

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91

Terminal Contact arm Variable resistor

Insulation Spring Resistor disk

Diaphragm

Figure 4-53 A thermistor used to sense engine temperature.

Oil pressure is applied to this area

Figure 4-54 A piezoresistive sensor used to sense oil pressure.

to the coolant temperature (Figure 4-53). As the temperature rises, the resistance decreases, and the current flow through the gauge increases. As the coolant temperature lowers, the resistance value increases, and the current flow decreases. Modern instrument panels are operated by an internal computer, a body control module (BCM), or an instrument panel (IP) module. The coolant temperature sensor is still a thermistor, but its signal serves as an input to the IP or to the BCM. The computer then drives an electronic gauge assembly to display the coolant temperature. The piezoresistive sensor sending unit is threaded into the oil delivery passage of the engine, and the pressure that is exerted by the oil causes the flexible diaphragm to move (Figure 4-54). The diaphragm movement is transferred to a contact arm that slides along the resistor. The position of the sliding contacts on the arm in relation to the resistance coil determines the resistance value and the amount of current flow through the gauge to ground. Again, the oil pressure sending unit may not be wired directly to the gauge; it may deliver its signal to the instrument panel cluster or the BCM. See the diagram showing this circuit (Figure 4-55).

A body control module (BCM) is a computer used to control many systems such as the instrument panel, radio, interior lighting, climate control, and driver information. A piezoresistive sensor is sensitive to pressure changes. The most common use of this type of sensor is to measure the engine oil pressure.

Warning Lamps A warning light may be used to warn of low oil pressure or high coolant temperature. Unlike gauge sending units, the sending unit for a warning light is nothing more than a simple switch. The style of switch can be either normally open or normally closed, depending on the monitored system. Most oil pressure warning circuits use a normally closed switch (Figure 4-56). A diaphragm in the sending unit is exposed to the oil pressure. The switch contacts are controlled by the movement of the diaphragm. When the ignition switch is turned to the on position with the engine not running, the oil warning light turns on. Since there is no pressure to the diaphragm, the contacts remain closed, and the circuit is complete to ground. When the engine is started, oil pressure builds and the diaphragm moves the contacts apart. This opens the circuit, and the warning light goes off. The amount of oil pressure required to move the diaphragm is about 3 psi. If the oil warning light comes on while the engine is running, it indicates that the oil pressure has dropped below the 3-psi limit. Most coolant temperature warning light circuits use a normally open switch (Figure 4-57). The temperature sending unit consists of a fixed contact and a contact on a bimetallic strip. As the coolant temperature increases, the bimetallic strip bends. As the strip bends, the contacts move closer to each other. Once a predetermined temperature level has been exceeded, the contacts are closed, and the circuit to ground is closed. When this happens, the warning light is turned on.

A warning light is a lamp that is illuminated to warn the driver of a possible problem or hazardous condition.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Chapter 4 Electronic instrument cluster SERVICE ENGINE SOON

195°F

45

1,700 rpm

BCM data line

km/h mph

ABS

Body control module (BCM)

Vehicle speed sensor (VSS)

IGN Data in Engine oil pressure switch

S

N

VSS input

VSS output

Data line

VSS input

Engine control module (ECM) Coolant temperature sensor

Figure 4-55 An electronic instrument panel with an internal integrated circuit.

Terminal +12 V

Spring

Contact points

Oil pressure warning lamp Oil pressure switch

Diaphragm

Oil pressure applied here (A)

(B)

Figure 4-56 (A) Oil pressure sending unit. (B) Oil pressure warning light circuit.

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B

BCM data line A

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93

+12 V Coolant temperature light Bimetallic strip

Contact points

Figure 4-57 Temperature warning light circuit.

Coolant temperature warning lights

+ –

Ignition switch in start position

Coolant temperature switch

Figure 4-58 A prove-out circuit included in the normally open (NO) coolant warning light circuit. Engine warning light

Ignition switch

Coolant temperature switch

Oil temperature switch

+ –

Figure 4-59 One warning light used with two sensors.

With normally open switches, the contacts are not closed when the ignition switch is turned to the on position. To perform a bulb check on normally open switches, a prove-out circuit is included (Figure 4-58). It is possible to have more than one sender unit connected to a single bulb (Figure 4-59). The light will come on whenever oil pressure is low or coolant temperature is too high.

Message Center Some vehicles have a message center that displays a number of warning messages to alert the driver regarding dangerous vehicle-operating conditions. Warning messages related to the lubrication and cooling system include low coolant, check coolant temperature, engine overheated, check engine oil pressure, check engine oil level, and change engine oil. The messages are displayed in the message center by

A prove-out circuit completes the warning light circuit to ground through the ignition switch when it is in the start position. The warning light will be on during engine cranking to indicate to the driver that the bulb is working properly.

Refer to Today’s Technician: Automotive Engine Performance for a detailed explanation of fuel system operation.

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the PCM. The PCM receives input signals from the ECT sensor. If the engine coolant reaches a specific temperature above the normal operating temperature, the PCM illuminates the check coolant temperature. If the engine coolant temperature increases a specific number of degrees, the PCM turns on the engine overheated message. Fluid level sensors are required to send a low coolant signal or a low engine oil signal to the PCM. The PCM looks at several different engine operating parameters to illuminate the change engine oil message. If the engine operating parameters such as engine temperature, engine on time, and rpm are continually in the normal operating range, the PCM will probably turn on the change engine oil message at the approximate interval recommended by the vehicle manufacturer for oil change intervals. However, under severe vehicle-operating conditions such as trailer towing, the engine temperature and load may be above normal, and the PCM may illuminate the change engine oil message at a lower mileage interval. As an example, on some vehicles, the change engine oil message comes on for 10 to 25 seconds each time the engine is started. After this time period, the message is turned off. After the oil is changed, the change engine oil message must be reset. As an example, on some vehicles, this is done by pushing the accelerator pedal wide open three times in a 5-second interval with the ignition switch on and the engine not running. Some vehicles may have a small button that can be pushed only by a pen tip, and others may require a scan tool to reset. Always consult the vehicle manufacturer’s service manual for the proper procedure.

FUEL SYSTEM The fuel system includes the intake system that is used to bring air into the engine and the components used to deliver the fuel to the engine. Multipoint fuel injection systems uses one injector for each cylinder to deliver fuel.

The fuel system is designed to deliver the correct amount of fuel to each of the cylinders for any engine operating condition. In this way, the engine can perform well while minimizing toxic emissions and increasing fuel economy. The PCM precisely controls the fuel delivery through its operation of fuel injectors. Air is brought into the engine through the intake system. A fuel injector is placed in the intake manifold near the opening to the cylinder. Most modern vehicles use one fuel injector for each cylinder; this is called multipoint fuel injection (MPFI). A few newer vehicles inject the fuel directly into the cylinder; this is called gasoline direct injection (GDI). Another system called the central port fuel injection (CPFI) uses poppet valves underneath the intake plenum. The fuel delivery system includes the fuel tank to store fuel, an electric fuel pump mounted in the tank to deliver fuel under pressure to the injectors, a fuel filter, a fuel-pressure regulator, and fuel injectors (Figure 4-60). The fuel control system includes the PCM and several inputs used to provide the PCM with enough information to determine how much fuel is required. The primary input for fuel delivery calculations is either a mass airflow (MAF) sensor or a manifold absolute pressure (MAP) sensor. The MAF sensor measures the mass of air flowing into the engine so the computer can calculate the proper amount of fuel to mix with it (Figure 4-61). A vehicle may use a MAP sensor instead to provide input for the PCM. The MAP sensor measures the pressure in the intake system to infer the amount of load on the engine. When the driver has the accelerator pedal all the way to the floor, the throttle opens the passage into the intake manifold and the pressure increases to atmospheric pressure. The PCM interprets this as a very heavy engine load and demand and delivers more fuel. The PCM also receives information about engine temperature, intake air temperature, air pressure, engine speed, throttle position, the level of oxygen in the exhaust, and more depending on the vehicle. When the PCM looks at all the data, it decides how much fuel should be injected and it opens the injector for exactly the right amount of time to deliver that quantity. The theoretically perfect air-to-fuel ratio is 14.7 parts of air to 1 part of fuel. During acceleration, the mixture must be “richer” (have more fuel). During deceleration, the PCM will “lean” out the mixture (give the engine less fuel

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to improve fuel economy). On many hybrids the engine will completely shut off when decelerating to save fuel. The injector has power applied all the time, and the PCM provides a ground pulse that times the injector opening; while the engine is idling, the injector on time may be 1 to 2 milliseconds. The injector has very small openings at its base to atomize the fuel. This means that it breaks the fuel into extremely small particles that can easily mix with the air to help support complete burning and powerful combustion (Figure 4-62). In-tank pump

Pressure regulator

Return fuel line

Supply fuel line

Fuel filter Engine vacuum line

Fuel rail

Injector

Figure 4-60 Fuel delivery system components.

Mass airflow sensor

Figure 4-61 The MAF sensor sits in the incoming airstream and senses the mass of airflow.

Figure 4-62 The fuel injector has a small pinhole-sized opening for fuel to be sprayed out under pressure.

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Chapter 4

Ignition System

Refer to Today’s Technician: Automotive Engine Performance for a detailed explanation of ignition system operation. The delivery of the spark used to ignite the compressed air-fuel mixture is the function of the ignition system. Burn time is the amount of time from the instant the mixture is ignited until the combustion is complete. An electronic-ignition system uses an electronic module to turn the coils on and off.

A distributor-ignition (DI) system has a distributor that distributes spark to each spark plug.

The compressed air-fuel mixture must be ignited at the correct time. The delivery of the spark is the function of the ignition system. If the spark is not delivered at the correct time, poor engine performance and fuel economy will result. Remember that fuel will burn inside the cylinder (called combustion), and so it does not explode. Burn time of the fuel plays into the calculation of spark delivery. Combustion should be completed by the time the piston is at 10 degrees after top dead center (ATDC) during the power stroke. If the spark occurs too early, when the piston is moving up during the compression stroke, the piston will have to overcome the combustion pressures. If the spark occurs too late, the combustion pressures are not as effective in pushing the piston down during the power stroke. In either case, power output is reduced. Engine speed is another consideration in spark delivery. As engine speed increases, the amount of piston movement also increases for the same amount of time. Burn time of the gasoline remains constant, but the piston will travel more as engine speed increases. To compensate for this, the spark must be delivered at an earlier time in the piston movement. The PCM controls the spark timing. It uses a crankshaft position sensor to determine the precise position of each piston. It may also use a camshaft position sensor to help identify each cylinder. The PCM also looks at many of the same inputs it uses for fuel delivery and then sends an output that allows the ignition coils to fire. The majority of modern ignition systems use multiple coils to fire the spark plugs. These systems are called electronic-ignition (EI) systems. Some EI systems use one coil to provide spark for two cylinders; these are called waste spark systems (Figure 4-63). Each coil fires two spark plugs at the same instant. One of the spark plugs is in the cylinder that is near TDC on the compression stroke; this spark will begin combustion on the power stroke. The other spark plug’s cylinder is on the exhaust stroke. The spark has no effect on engine operation, hence the term waste spark. Other EI systems place a coil on top of each spark plug; this eliminates sensitive high-voltage wiring. These are called coil-on-plug (COP) systems (Figure 4-64). Other ignition systems use one coil to fire all the spark plugs. These systems use a mechanical distributor to deliver the spark to the correct cylinder; these are termed distributor-ignition (DI) systems. EI systems use coils to deliver high voltage to the spark plug. The high voltage forms a spark as it jumps across the gap of the spark plug electrodes. The coils have power available to them whenever the engine is running. The PCM provides a ground to turn

Figure 4-63 This coil pack is for a four-cylinder engine; it has two coils, each with two outputs. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Ignition coils

Figure 4-64 These coils sit directly on top of the spark plugs.

PCM V Bat

Gnd

Ignition coils 1

+

Coil 1 Ignition module

5 3

Coil 2

4 2

Coil 3

Camshaft sensor

6

Crankshaft sensor

Figure 4-65 This EI system uses an ignition module to provide a ground for the coils.

the coils on and off. In some cases, the PCM provides the ground directly to the coils; in other cases, the PCM provides inputs to an ignition module and it provides the ground to the coils (Figure 4-65).

Emission Control System The emission control system helps reduce the harmful emissions resulting from the combustion process. The PCM and its engine management system are integral parts of controlling emissions. The PCM is part of a complex system that controls many aspects of how the vehicle operates. It is often paired up and coordinated with other computers in the vehicle to make the vehicle operate smoothly. Spark timing, fuel injection, and several other systems are controlled by the PCM to minimize the output of toxic emissions. Modern engine management systems do an excellent job of cleaning up tailpipe and evaporative emissions. One study showed that driving a two-stroke snowmobile for 7 hours produced more emissions than a 2000 model year vehicle driven 100,000 miles.

The emission control system includes various devices connected to the engine or exhaust system to reduce harmful emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NO x ).

Refer to Today’s Technician: Automotive Engine Performance for a detailed explanation of emission system operation.

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Chapter 4

Gasoline has many ingredients and compounds. It is refined from crude oil and is the most common fuel used in today’s engines.

The octane number is the ratio of two test fuels that match the knock characteristic of the test fuel. The advertised octane number at a gas station is an average of RON and MON and is an indicator of the fuel’s antiknock quality. Lower octane fuels will burn faster. Higher octane fuels will burn slower. RON (research octane number) and MON (motor octane number) are octane testing numbers that are averaged together to get the advertised octane number. Each uses a different test procedure that represents different realworld driving situations.

While modern engines release less than 10 percent of the toxic pollutants that they did in the 1970s, the automobile is still a primary source of air pollution in the United States, Canada, and other industrialized countries. Hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NO x ) are all formed during the combustion process. When an engine is running poorly, the emissions greatly increase. Emission control devices minimize the pollutants by affecting combustion, cleaning up the post-combustion emissions, and controlling the evaporative emissions that occur when a vehicle is not being driven or when it is being refueled. The actual controls on an engine depend upon the design of the engine. Many vehicles use the following emission control systems: ■ Catalytic converter ■ Secondary air injection system ■ Positive crankcase ventilation valve (PCV) system ■ Exhaust gas recirculation (EGR) system ■ Evaporative emissions system ■ Variable valve timing (VVT) system

AUTOMOTIVE FUELS Gasoline Gasoline is a mixture of many ingredients, such as hydrocarbons and various other chemicals and additives. Hydrocarbon compounds are refined from crude oil that is removed from the earth. Crude oil is refined into many products, including gasoline, diesel fuel, plastics, soaps, fertilizers, and asphalts. The refining process separates the light liquids from the heavy liquids. The lighter liquids are typically used for producing gasoline, and the heavier liquids are used for producing waxes and asphalts.

Octane The antiknock quality of gasoline is rated with the term octane. The advertised octane number on the gas station pump is the average of two methods of measuring a fuel’s octane. Both RON (research octane number) and MON (motor octane number) are laboratory test methods of measuring a fuel’s octane (Figure 4-66). The octane rating of a fuel is used by manufacturers to determine which fuel is appropriate to use for a specific engine.

Figure 4-66 These are the most common octane ratings available. Note the (R 1 M/2) method. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-67 Detonation can cause severe damage.

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Figure 4-68 Knock sensor

Higher-performance engines with higher compression ratios typically use a premium gas that has a higher octane number. More normal engines with normal compression ratios will most likely use a regular or mid-grade fuel. The compression ratio is the main determining factor in the octane choice of a fuel, but other factors such as fuel delivery method, intake manifold design, and combustion chamber design are also considered. The minimum octane rating must always be observed and used for several reasons. The main reason is to protect the engine from detonation (also known as spark knock). Detonation occurs when two flame fronts collide in the combustion chamber (Figure 4-67). The first flame front is normal and created by the spark plug. The second flame front is created because of high temperatures. The collision could cause serious damage to the piston if it is not corrected immediately. Fuels with a lower octane number will burn faster than those with a higher octane number. A higher octane fuel will slow down the flame speed and give less of a chance for detonation to occur. Modern engines and computer systems use a knock sensor to detect if there is an abnormal explosion in the combustion chamber (Figure 4-68). If an abnormal explosion is detected, the PCM will usually retard the ignition timing, which lowers the temperature of the combustion chamber and usually stops the detonation. The octane number itself does not have any effect on fuel efficiency or economy; however, if a lower-than-recommended octane number is used, the PCM may change the spark timing to compensate and the fuel economy may suffer. Using a higher-thanrecommended octane will not directly affect the engine’s performance or the fuel economy. After an engine rebuild, the octane requirement may change due to the excessive machining and possible exchange of parts, such as pistons, crankshaft, or cylinder heads, especially if you rebuild an engine to have more performance or a higher compression ratio. During an engine rebuild, you should always remain aware of how machining and upgrading components will affect the compression ratio. The octane requirement can also be affected by the air-fuel mixture, valve timing, coolant temperature, carbon deposits, and turbo-/supercharging.

A knock sensor is used to detect abnormal combustion. Its data is used by the PCM to change the ignition timing.

Volatility Gasoline has to be very volatile so it can easily evaporate and readily mix with air to support combustion. Vaporized fuel and air will support combustion, and volatility describes how easily the gasoline evaporates. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Gasoline blended in the summertime (or year-round in very warm climates) is less volatile than winter blends. The more volatile a fuel is, the more vapor pressure it will create in the fuel line and system components at a given temperature. Different pressures are required because engines need to operate in a variety of conditions. During hot temperatures, a fuel that vaporizes too quickly can develop vapor bubbles in the fuel line and block the flow of liquid to the engine. This is called vapor lock. During cold temperatures, the fuel needs to vaporize quickly so that it can mix with the cold incoming air in the combustion chamber.

Ethanol Ethanol is an alcohol that can be used as an automotive fuel.

Ethanol is an alcohol that can be used as an automotive fuel. Ethanol (ethyl alcohol) behaves similarly to gasoline and is commonly blended with gasoline as an additive. Ethanol is a noncorrosive, low-toxic-level alcohol that is made from renewable biological sources. In the United States, ethanol is typically made from corn. The starch and sugars from the corn are processed in a fermenting tank at an ethanol-producing plant. Distillation towers are then used to separate water from the alcohol. Ethanol is typically blended in with gasoline and is used as an additive and octane improver. Ethanol is an oxygenated fuel that helps reduce the toxicity of burning regular gasoline. Ethanol also helps keep the fuel system cleaner and less subject to corrosion. Ethanol, like other alcohols, absorbs water readily. Water is formed in the fuel system by condensation. If it is not absorbed, it will rust out system components and possibly “freeze” the fuel line in the winter. Currently, ethanol blends of up to 10 percent are approved by all manufacturers and do not void their warranty. Ethanol’s volatility is significantly lower to gasoline, the only condition that makes it unsuitable for cold weather use. Ethanol burns cooler than gasoline does. This reduces the risk of valve burning and detonation, two common side effects of excessive heat. Ethanol also has an octane rating of over 100, which makes it a suitable fuel for advancing the ignition timing and running a higher compression ratio. Ethanol has a lower energy rating than gasoline does. One hundred percent ethanol has about 76,000 Btus/gallon, and 100 percent gasoline has about 125,000 Btus/gallon. The traditional gasoline that you would find at a gas station is mixed with ethanol, which reduces the amount of energy in the fuel because of the mixture rate. Ethanol is typically found blended at a rate of 85 percent ethanol and 15 percent gasoline. This blend is called E85. Flex fuel vehicles are specifically set up to operate on E85, gasoline, or any blend in between. Vehicles that are not designed by the manufacturer to operate on E85 should not be operated with E85 without extensive modifications, as it could cause engine or fuel system damage. More about ethanol and flex fuel vehicles is found in Chapter 14.

Additives

TEL is not used as an additive in gasoline anymore. Unleaded gasoline is readily available and is less toxic.

Gasoline by itself does not properly serve the needs of the modern engine. Gasoline additives have changed over the years to meet the demands of different engine types and driving patterns. Tetraethyl (TEL) lead was added to gasoline in the 1920s. Originally, lead was added to gasoline to improve the antiknock quality. After lead was added to gasoline, engines started to have higher compression ratios, and vehicles went faster and farther on a tank of fuel. On vehicles that were driven hard, the added lead also helped to lubricate hot exhaust valves to lower the chances of valve recession. Years later, it was found that the lead was contaminating the drinking water and causing a few cases of lead poisoning. Lead also poisons the catalytic converter. The practice of using lead as an additive was stopped. Unleaded fuels were commonly used as early as the mid-1970s. Leaded fuel is no longer used or available for on-road automotive use. Lead also poisons catalytic convertors by coating its active precious metals. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Oxidation inhibitors prevent the formation of gum and varnish on components. When gasoline is not used for a prolonged period of time, its evaporates can mix with oxygen and form a residue on system components. Detergents are designed to clean fuel systems and components. Gasoline can sometimes contain microscopic particles of dirt that can, with time, cause fuel filter or fuel injector clogging. The amount of detergents varies greatly between different manufacturers. The amount of detergent necessary may also be dependent on the design of the fuel system.

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The formation of gum and varnish is prevented by oxidation inhibitors. Detergents are gasoline additives that clean the fuel system.

Diesel Fuel Diesel fuel acts very different than gasoline or ethanol and has very different characteristics. A diesel engine does not use spark plugs for the ignition of the fuel-air mixture (Figure 4-69). It uses the heat developed by the compression stroke. It is very important that diesel fuel is clean and able to flow at low temperatures for good engine longevity and performance. Diesel is typically a product of crude oil at a distillation station, similar to gasoline. But there are other ways to produce diesel fuel. Some examples are biodiesel, which can be produced from crop and renewable products. Another example is biomass-to-liquid (BTL), which uses waste, garbage, sewage, and used cooking oils. Recently, gas-to-liquid (GTL) technology has proven successful. GTL is a diesel fuel that is produced from natural gas reserves found in the earth. Diesel fuel is not rated by the octane scale, but rather it uses a different scale called the cetane scale. The cetane number is a measure of how easily the fuel can be ignited. The cetane number is an indicator of the fuel’s ability to start the engine in low temperatures and smoothly warm up the engine. Typically, the cetane rating for automotive and light truck diesel fuel is between 40 and 50. Diesel fuel is denser than regular gasoline. Diesel fuel weighs about 7.09 lbs/gallon, while gasoline weighs about 6.01 lbs/gallon. Diesel fuel contains significantly more energy than gasoline or ethanol. At approximately 138,000 BTU’s per gallon, it gives diesel engines that extra energy to make more power and get better fuel economy. Diesel engines are also more efficient because of the

Diesel fuel is any fuel that will operate in a diesel (compression ignition) engine. It is named after its inventor, Rudolf Diesel. Diesel fuel has a lower volatility rating than gasoline. It can be derived from petroleum or alternative sources such as biomass, natural gas, or soy beans. The cetane number of a fuel is the measurement of how easily a diesel fuel can be ignited.

Figure 4-69 Diesel engines use high-pressure injectors to inject the fuel directly into the cylinder. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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higher compression ratio, average lower operating speeds, and a slower, more complete burn inside the cylinder. Diesel fuel inherently has high sulfur content. The sulfur was traditionally used for lubrication in the cylinder. Recent ultra-low sulfur diesel (ULSD) laws have forced the sulfur level to decrease, and additives are now being used. Biodiesel is becoming a common additive because of its good lubricity properties. Sulfur in the exhaust and the atmosphere are major components of acid rain. Ultra-low sulfur diesel standards have been in place in the United States since 2007. These new fuels allow for the use of new technology emissions devices that significantly clean up the exhaust. Diesel fuel quickly increases its viscosity as the temperature decreases. Two grades of diesel fuel are commonly available. Diesel number 1 is a less dense fuel with lower heat content. Diesel number 2 is more popular and is more common during summer months and for on-road vehicles. It is common to blend a little bit of number 1 into number 2 in colder temperatures to keep the fuel from gelling. Off-road diesel (non-highway commercial use) is also available in the United States. This fuel is untaxed and does not meet the emissions levels for on-road use. It is primarily used for agriculture applications and is dyed red in color. Diesel fuel is also immiscible with water—meaning it does not mix with water. Small microbes can grow where the water and fuel come in contact. These microbes feed off the fuel and cause filter clogging, injection problems, and engine problems. Diesel engines have filters and water separators that need to be maintained. Biodiesel fuels are blends of organically made fuel and regular fuel. Biodiesel itself burns cleaner and does not contain any petroleum. Biodiesel blends with regular fuel are very common. Common blends are B20 and B5. Many manufacturers have approved their engines to operate on a small mixture of biodiesel.

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The starting system is a combination of mechanical and electrical parts that work together to start the engine. The starting system components include the battery, cable and wires, the ignition switch, the starter solenoid or relay, the starter motor, the starter drive and flywheel ring gear, and the starting safety switch. An automotive battery is an electrochemical device that provides for and stores electrical energy. Electrical energy is produced in the battery by the chemical reaction that occurs between two dissimilar plates that are immersed in an electrolyte solution. The lubrication system provides an oil film to prevent moving parts from coming in direct contact with each other. Oil molecules work as small bearings rolling over each other to eliminate friction. Another function is to act as a shock absorber between the connecting rod and the crankshaft. Many different types of additives are used in engine oils to formulate a lubricant that will meet all of the demands of today’s engines. Synthetic oils are superior to conventional oils because they provide better protection from engine wear. Oil is rated by two organizations: the Society of Automotive Engineers (SAE) and the American

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Petroleum Institute (API). The SAE has standardized oil viscosity ratings, while the API rates oil to classify its service or quality limits. Oil filter elements have a pleated paper or fibrous material designed to filter out particles between 20 and 30 microns. There are two basic types of oil pumps: rotor and gear. Both types are positive displacement pumps. The radiator is a series of tubes and fins that transfer heat from the coolant to the air. The radiator cap allows for an increase of pressure within the cooling system, increasing the boiling point of the coolant. The water pump is the heart of the engine’s cooling system. It forces the coolant through the engine block and into the radiator and heater core. Control of engine temperatures is the function of the thermostat. When the coolant is below normal operating temperature, the thermostat is closed, preventing coolant from entering the radiator. When normal operating temperature is obtained, the thermostat opens, allowing the coolant to enter the radiator to be cooled. In a reverse-flow cooling system, coolant flows from the water pump through the cylinder heads and then through the engine block.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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In some instrument panels, a message center displays specific warning messages to alert the driver regarding dangerous vehicle operating conditions. Modern vehicles use multipoint fuel injection systems that provide precise control of fuel delivery. Some engines have electronic distributor-ignition (DI) systems, while most engines manufactured at present have electronic-ignition (EI) systems, which do not have a distributor. Emission control systems minimize emission of toxic pollutants NO, CO, and NO x . Gasoline is a mixture of many ingredients, such as hydrocarbons and various other chemicals and additives.

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Gasoline has to be very volatile so that it can easily evaporate and readily mix with air to support combustion. Ethanol (ethyl alcohol) is a noncorrosive, lowtoxic-level alcohol that is made from renewable biological sources. It behaves similarly to gasoline and can be mixed with 15 percent gasoline to form E85, which is used in flex fuel vehicles. Detergents are designed to clean fuel systems and components. Diesel fuel contains significantly more energy than gasoline or ethanol and is rated by its cetane number.

REVIEW QUESTIONS Short-Answer Essays 1. What are the purposes of the engine’s lubrication system?

4. A pressure relief valve opens to return oil to the sump if the pressure is _______________.

2. Explain the purpose of the Society of Automotive Engineers’ (SAE) classifications of oil.

5. If the oil filter becomes plugged, a _______________, _______________ will open and allow the oil to enter the galleries.

3. List the three most recent API’s classifications of oil. 4. Describe the two basic types of oil pumps: rotary and gear. 5. What is the purpose of the starting system? 6. Explain the operation of the thermostat.

6. Coolant can become slightly acidic because of the minerals and metals in the cooling system. A small _______________ may flow between metals through the acid and have a corrosive effect on the metals.

8. Explain the function of the water pump.

7. For heat to be effectively transferred to the air, there must be a_______________ in temperature between the coolant and the air.

9. Explain the purpose of the pressure and vacuum valves used in the radiator cap.

8. E85 is composed of _______________ percent ethanol and _______________ percent gasoline.

7. Describe the function of the radiator.

10. Describe the purpose of antifreeze, and explain its characteristics.

Fill-in-the-Blanks 1. It is the function of the engine’s lubrication system to supply oil to the _______________ and _______________ locations and to remove heat from them. 2. The Society of Automotive Engineers has standardized oil _______________ ratings, while the American Petroleum Institute rates oil to classify its service or quality limits. 3. Oil pumps are _______________ displacement pumps.

9. Diesel contains significantly _______________ energy than gasoline or ethanol. 10. The fuel system uses a _______________ sensor or a _______________ sensor as its primary input for fuel calculations.

Multiple Choice 1. Each of the following is a function of the lubrication system, except: A. Provides oil pressure to the crankshaft journals B. Cushions the shock between the connecting rod and the crankshaft C. Splashes lubricate the cylinder walls D. Provides oil pressure to the piston pins

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2. Technician A says that the oil pressure increases as the temperature increases. Technician B says that the oil pressure decreases as the engine speed increases. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. A likely cause of low oil pressure is A. the oil pressure relief valve sticking open. B. a defective inlet check valve. C. the oil filter bypass valve opening. D. dirty oil galleries. 4. Coolant and water should be mixed in the ratio of A. 70/30. C. 40/60. B. 50/50. D. 100/1. 5. Each of the following is a function of the radiator cap, except: A. Holds pressure on the system to raise the boiling point B. Releases excess pressure to prevent damage C. Seals the radiator to prevent toxic leaks D. Holds a vacuum on the system to maintain a proper seal

7. Technician A says that electric cooling fans reduce the load on the engine, saving horsepower. Technician B says that a clutch-type fan slips on the pump hub when the engine is hot. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Each of the following is an input to the PCM for fuel delivery, except: A. Engine coolant temperature B. Engine speed C. Exhaust oxygen content D. Thermostat position 9. The type of ignition system that uses one coil to fire two cylinders. A. DI C. Distributor B. Coil-on-plug D. Waste spark 10. Each of the following is a toxic pollutant created by the automobile, except: A. NO x C. N 2 B. CO D. HC

6. Technician A says that when the thermostat opens the coolant flows through the radiator. Technician B says that thermostats usually last the life of the engine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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CHAPTER 5

FACTORS AFFECTING ENGINE PERFORMANCE

Upon completion and review of this chapter, you should understand and be able to describe: ■

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The common engine mechanical causes of improper engine performance. The components that seal the combustion chamber. The effects of combustion chamber sealing problems on engine performance.

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Fuel volatility and its effect on engine performance. The octane rating and explain its effects on combustion. The different forms of abnormal combustion. The potential causes and effects of abnormal combustion.

Terms To Know Autoignite Detonation Knock sensor (KS)

Misfire Octane rating Preignition

Reid vapor pressure (RVP) Volatility

INTRODUCTION Proper engine performance requires that the engine is mechanically sound and that its support systems are functioning as designed. One of the most important tasks in engine repair is determining the precise cause of the concern. Before you make engine mechanical repairs, you must gather as much information as possible. There are many different reasons why an engine can perform poorly. You will need to understand the requirements for proper engine performance before you can successfully diagnose the reasons for performance failures. In this chapter, we will look at the areas of the engine that can affect performance and create a need for mechanical repairs. Components as common as spark plugs can cause an engine to perform as though it has a “dead” cylinder(s). Problems that occur related to the combustion chamber may require special test procedures. Smoke coming from the tailpipe is never a good sign (Figure 5-1). Some causes may be relatively simple and inexpensive to rectify, while others may require a complete engine overhaul or replacement. You will need to understand the possible causes of engine smoking to correctly diagnose the cause of the unwanted emission of smoke. As engine components wear, clearances become greater, parts break, and noises develop in the engine. These can be warning signs that a component is wearing, or they can predict imminent engine failure. Training, experience, and careful listening can help you narrow down the possible causes of unusual noises and recommend effective repairs (Figure 5-2).

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Figure 5-1 A lot of thick blue smoke can require serious engine mechanical repairs or relatively inexpensive and simple cures. Your task will be to properly diagnose the cause to make an effective repair.

Figure 5-2 You will listen in different engine areas to identify unusual noises.

Figure 5-3 The spark plugs must be functioning well for the engine to provide good performance.

SPARK PLUGS Spark plugs are the workhorses of the ignition system. All the buildup of electrical energy of the coil(s) comes to a head at the spark plug gap (Figure 5-3). The electrodes of the spark plug must provide an adequate electrical path. If the spark is well timed and strong Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Factors Affecting Engine Performance

enough, it jumps the gap with a powerful burst. Then the conditions within the combustion chamber determine whether the spark will ignite the air-fuel mixture well enough to foster good combustion. Inspecting the spark plugs is a method you will use to gather information about how the engine is operating. You may use this during a routine tune-up, when there is a drivability concern, and as part of gathering information about an engine mechanical failure. Spark plugs can give you tremendous insight into what has been occurring within the combustion chambers. When you have a drivability concern, one of the first areas to begin investigating is the spark plugs. This can help identify if one or more cylinders are acting up or if all cylinders are affected. Spark plugs can also help guide your diagnosis toward a fuel, ignition, or mechanical issue, for example.

AUTHOR’S NOTE Many technicians will use nothing but OEM (original equipment from the manufacturer) spark plugs on late-model vehicles. Today’s PCMs and their monitoring systems are very sensitive; using aftermarket spark plugs is a very common cause of drivability problems and customer complaints. Vehicle manufacturers work closely with spark plug manufacturers, and both spend a lot of time and money designing the spark plug that will deliver the perfect spark for the individual combustion chamber. Many aftermarket companies produce excellent spark plugs. Unfortunately, they are usually designed to fit several applications. This does not guarantee that they will operate exactly like original equipment in each vehicle. In some cases you will find that aftermarket spark plugs will not cause major issues. If you do find quality aftermarket spark plugs that perform properly in an engine, it is appropriate to use them. Many technicians have a spark plug brand they have come to trust and use it on many, if not all, applications successfully. You will have to make this judgment call as a professional technician.

COMBUSTION CHAMBER SEALING Proper combustion is the key to the engine’s power production. Fuel must be delivered in the correct quantity; a strong spark must be ignited at precisely the right instant, and the combustion chamber must be full of a fresh charge of air. Then the combustion chamber must be properly sealed for the engine to be able to harness the power of combustion. The spark plug, the engine valves, the head gasket, as well as the piston, rings, and cylinder walls seal the combustion chamber (Figure 5-4). Each of those components must be functioning properly, or the piston strokes cannot achieve their optimum result and engine performance will deteriorate. On the intake stroke, the engine creates a vacuum so a charge of fresh air can enter into the cylinder. If any of the components that form a seal for the combustion chamber are leaking, adequate vacuum level will not develop. Reduced vacuum levels can affect the ratio of air and fuel, causing the cylinder not to contribute its share of power (Figure 5-5). The more air an engine can take in, the more power it can put out. If an exhaust valve is leaking, residual pressure will be present in the cylinder when the piston moves down on the intake stroke. Exhaust from the exhaust manifold will join with the fresh air from the intake manifold and dilute the charge. These effects will create significantly rough engine operation and a loss of engine power. Any other combustion chamber leaks would have a similar effect on the intake stroke. The compression stroke should develop somewhere between 125 and 200 psi of pressure while the engine is cranking. This is a widely generalized estimate; always refer to the Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Throttle body Spark plug gasket or seat

Exhaust valve

Intake valve

Intake manifold runner

Head gasket

Piston rings

Figure 5-4 A leak through any of these combustion chamber sealing points will lead to engine performance problems.

A misfire means that combustion is either incomplete or does not occur at all.

Variable valve timing (VVT) can be used to lower the emission of NO X . It does this by closing the exhaust valve later and opening the intake valve earlier, thereby increasing a valve overlap, and causing exhaust gas to dilute the incoming intake charge.

Figure 5-5 The engine needs a strong vacuum from the cylinder to pull air through the intake runners and into the cylinder.

manufacturer’s specifications when evaluating a specific engine. Compression of the airfuel mixture adds heat and pressure to the mix to make it more combustible. If compression is low, the spark may not be able to develop a strong flame front. Or the flame may start but sputter out as it hits loosely held areas of cooler air and fuel. This would cause incomplete combustion or even a total misfire. A misfire is when combustion does not take place. Any leaks past the valves, head gasket, piston, rings, and cylinder walls would lower the amount of compression a cylinder can develop. Leaks in the combustion chamber reduce the power of combustion. All the force of the expanding gases should be exerted on the top of the piston. This pushes the piston down and turns the crankshaft through the connecting rod. A cylinder has the potential to develop roughly 2,000 lbs. of force on top of the piston. If one quarter of that force leaks past worn piston rings and cylinder walls, the driver will definitely notice that lack of power. This is a typical scenario of a worn, high-mileage engine. The engine could also leak those forces past a burned intake or exhaust valve (Figure 5-6). The power loss would be evident, but the consumer would also likely notice a popping noise in the intake or exhaust, depending on which valve(s) had failed.

Ring and Cylinder Wall Wear Piston rings will normally develop wear as the engine accumulates miles. Out of the box they have very sharp edges; these wear down over time and compromise their ability to seal against the cylinder walls (Figure 5-7). When piston rings wear, they may allow combustion gases to leak down into the crankcase. They may also let oil track up the cylinder walls into the combustion chamber, where they are burned. This is one of the primary causes of bluish smoke exiting the tailpipe. It is called oil consumption when oil is burning in the combustion chamber. It is important to remember that some oil consumption is considered normal. The piston’s rings will not completely seal all of the oil from the combustion chamber. The amount of oil consumption (oil burning) varies with engine load, driving style, type of oil, and amount of wear of the engine. One of the primary processes of an engine overhaul is replacing the piston rings and refurbishing the cylinder walls.

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Figure 5-6 A burned valve will significantly reduce the power output of an engine and cause rough running.

Figure 5-7 The cylinder walls must be in excellent condition to allow the rings to seal the combustion chamber properly.

Valve Wear Intake and exhaust valves can wear in a few different ways. The most dramatic problem they encounter is when they burn. Valves generally burn when they are open during combustion and exposed to the extreme combustion temperatures. This can happen when the valve springs become weak and cannot close the valves at the proper time, particularly when the engine is spinning at high speeds. When the engine is revving high, the momentum of the valve opening is greater and a slightly weak spring may not be able to close the valve at the proper time. With the valve face and margin exposed to combustion temperatures, the valve will rapidly burn. The valve faces and seats can also become pitted from the corrosive by-products of combustion or can develop carbon buildup on the seats (Figure 5-8). In either case, leakage past the valve face and the seat can occur. Again, once combustion temperatures can leak past parts of a valve, the parts tend to burn rapidly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-8 A pitted valve face allows leakage that will eventually cause the valve to burn.

Misadjusted valves can also cause valve leakage and burning. If a valve is adjusted too tightly, it will be held open longer than it was designed to. This can cause a reduction in performance through poor sealing of the combustion chamber during the appropriate strokes. In extreme cases, it can also cause the valves to burn if they are exposed to excessive temperatures.

A BIT OF HISTORY As recently as the mid-1980s, it was not uncommon for engines to require valve reconditioning as early as 60,000 or 75,000 miles. Now due to advances in materials and machining, most of today’s engines can run at least 150,000 miles before requiring valve service.

Head Gasket Damage When a head gasket leaks, it can present a whole host of different symptoms. In the context of combustion chamber sealing, a failure usually results in a leak between two adjoining cylinders. This will lower the compression and combustion of both cylinders significantly. This will cause rough running and a lack of power. Combustion gases can also leak out into the cooling system. This can cause the cooling system pressure cap to release pressure and coolant. The most common symptom of a blown head gasket is coolant leaking into the combustion chamber. Another common symptom of head gasket failure is the presence of coolant in the oil. The oil dipstick will show signs of coolant mixing with the oil, and it will look foamy and brownish, like a coffee milkshake. In these situations, a complete engine rebuild may be required. This burning coolant causes clouds of white, sweet-smelling exhaust to exit the tailpipe (Figure 5-9). There is a significant difference in cost, labor, and technique, depending on what problems exist with combustion chamber sealing. It will be your job to recognize the possible causes of low performance, in order to offer the customer responsible repair options with a realistic estimate. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-9 A blown head gasket often results in a cloud of white smoke.

FUEL AND COMBUSTION When combustion does not occur normally, severe engine damage can result. It is important that you are aware of the causes of abnormal combustion. When you repair or replace an engine with a catastrophic failure, you need to find the source of the problem so it doesn’t happen again (Figure 5-10). The fuel that customers use can have a significant impact on their engine performance and durability. Your customers may ask your advice about what type of fuel to use and why. You will also see drivability problems caused by fuel issues affecting combustion.

Octane Rating The octane rating of a fuel describes its ability to resist spontaneous ignition or engine knock. Engine knocking (detonation) or pinging (preignition) results when combustion occurs at the wrong time or at the wrong speed. Low octane fuel can be a cause of

A octane rating of a fuel describes its ability to resist detonation (also known as spark knock).

Figure 5-10 This diesel head gasket has multiple steel layers; yet it did not hold up to the pressures and stresses of the combustion chamber and engine when it overheated due to a cooling system malfunction. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-11 Make sure your customer is using the correct octane fuel to prevent abnormal combustion.

preignition and detonation. If combustion begins before the spark, for example, combustion pressures may try to push the piston backward at the end of the compression stroke. This results in a rattling noise from the piston. This is called preignition, and the sound is often described as pinging. Fuel is generally available for automobiles as regular, 87 octane; mid-range, 89 octane; or as premium, 92 octane or 93 octane (Figure 5-11). The higher the octane number, the greater its resistance to knock. Octane is tested in two ways, by the research method and by the motor method. The advertised octane rating is the average of the two ratings. You will often see this described on the pumps as: Octane 5

RON 1 MON 2

Volatility Fuel volatility is the ability of the fuel to vaporize. The higher the volatility, the easier it is for the fuel to evaporate; this allows easier cold starts. Reid vapor pressure (RVP) is a method of describing the volatility of the fuel. You can test the RVP to rate the fuel’s volatility.

Fuel volatility is the ability of the fuel to vaporize (evaporate). The Reid vapor pressure (RVP) defines the volatility of the fuel. The RVP is the pressure of the vapor above the fuel in a sealed container heated to 1008F . The higher the pressure of the vapor, the greater the volatility of the fuel. This means that the fuel will more readily vaporize. Fuel volatility is adjusted seasonally in many parts of North America. A higher volatility fuel is allowed in the winter to help the engine start when it is cold. The fuel vaporizes more easily during compression rather than puddling along the cool walls of the combustion chamber. A fuel with very low volatility will cause hard starting and rough running at start-up. A lower volatility fuel is used in the summer to reduce the amount of evaporative emissions and to prevent vapor lock in the fuel lines. A fuel with very high volatility used in the summer months can cause extended cranking times. This occurs because the fuel actually boils in the fuel lines, allowing air in the fuel stream after the vehicle is shut off. When the vehicle is restarted, it takes a significant time for the pump to develop fuel pressure.

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Factors Affecting Engine Performance

Figure 5-12 Normal combustion allows a flame front to travel rapidly across the cylinder and develop the peak force of combustion at about 10 degrees after top dead center.

Combustion Issues Combustion is the chemical reaction between fuel and oxygen that creates heat. It is a closely controlled burning of the air and fuel. Spark ignition occurs before top dead center on the compression stroke. The hot, compressed, air-fuel mixture is ignited, and a flame front develops. For normal combustion to occur, the air-fuel mixture must be delivered in the proper proportions and mixed well, the spark must be timed precisely, and the temperatures inside the combustion chamber must be controlled. The flame can then move quickly and evenly (propagate) across the combustion chamber, harnessing the power of the fuel as heat. Pressure builds steadily as the gases expand from heat. The peak of this pressure develops around 108 ATDC to push the piston down on the power stroke (Figure 5-12).

Abnormal Combustion Normal combustion takes about 3 milliseconds (3/1,000 of a second). One form of abnormal combustion, detonation, is more like an explosion, occurring as fast as 2 millionths of a second (2/100,000 of a second). The explosive nature of detonation can potentially cause engine damage. Preignition is a form of abnormal combustion when part of the compressed air-fuel mixture ignites before the spark. Engine misfire is another form of abnormal combustion; it causes the engine to run poorly and lack power.

Preignition Preignition means that a flame starts before intended spark time. This premature ignition can happen when a hot spot in the combustion chamber autoignites the fuel. A flame front develops and starts moving across the chamber (Figure 5-13). Then the spark occurs, and the normal flame front develops. When these two flame fronts collide, a pinging or knocking is heard. Preignition causing pinging can lead to the more damaging detonation by overheating the cylinder. Hot spots in the combustion chamber, the wrong spark plug, cooling system problems, lean air-fuel ratio, low octane fuel, over-advanced timing or metal edges sticking out from the head gasket are some of the reasons preignition can occur. Preignition can lead to engine damage such as melting the center of pistons. But preignition is less likely to cause major engine damage than detonation. It is also less likely than detonation to cause loud spark knock before it causes engine damage. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Hot carbon deposit

A

B

C

Figure 5-13 The preignition process is started when an uncontrolled flame front is started too soon. (A) An uncontrolled flame front is started before the spark by a hot carbon deposit. (B) The spark plug is fired. (C) The flame fronts collide.

Detonation Detonation occurs when combustion pressures develop so fast that the heat and pressure will “explode” the unburned fuel in the rest of the combustion chamber. Before the primary flame front (ignited by the spark plug) can sweep across the cylinder, the end gases ignite in an uncontrolled burst (Figure 5-14). The dangerous knocking results from the violent explosion that rapidly increases the pressure and temperature in a cylinder. This can be caused by engine overheating, over-advanced timing, low EGR system flow, low octane fuel, and other factors affecting the combustion chamber. In a short period of time detonation can cause serious engine damage, such as bent connecting rods and badly damaged pistons and ring lands (Figure 5-15).

Knock Sensor A knock sensor (KS) screws into the engine and creates an electrical input for the PCM when abnormal knocking is detected.

Most modern engines are equipped with a knock sensor (KS). The knock sensor creates an electrical signal when it senses a particular frequency of knocking or detonation. This signal serves as an input to the engine computer, the powertrain control module (PCM). When knocking is detected, the PCM modifies the spark timing to reduce the potentially dangerous knocking (Figure 5-16).

Preignition damage

Detonation damage A

B

C

Figure 5-14 Detonation results from an uncontrolled flame front that is started after the spark plug is fired. (A) Combustion begins. (B) Detonation or postspark begins a second flame front. (C) The two flame fronts collide to create a knocking sound.

Figure 5-15 Results of the extra stress placed on the piston due to detonation or preignition.

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Factors Affecting Engine Performance

Figure 5-16 The knock sensor screws into the engine to detect abnormal engine knocking.

Misfire Misfire is another type of abnormal combustion. When an engine misfires, it means that one or more of the cylinders are not producing their normal amount of power. The cylinder(s) is (are) unable to burn the air-fuel mixture properly and extract adequate energy from the fuel. The misfire may be total, meaning that a flame never develops and the air and fuel are exhausted out of the cylinder unburned. Hydrocarbon emissions increase dramatically. Misfire may also be partial when a flame starts but sputters out before producing adequate power (due to a lack of fuel, compression, or good spark). When an engine is misfiring, the engine bucks and hesitates; it is often more pronounced under acceleration. Technicians normally call this a miss or a skip. On modern vehicles (1996 and newer) equipped with the OBD II system, a misfire DTC will be set when the PCM detects a single- or multiple-cylinder misfire. This can help guide your diagnosis. A P0300 DTC means that the PCM has detected a multiple-cylinder misfire. A DTC P0301 means the PCM has detected a misfire on cylinder number 1, and right up to DTC P0312, a misfire on cylinder number 12.

Support Systems’ Contribution to Abnormal Combustion When the cooling, lubrication, intake, exhaust, or fuel system is not functioning properly, it can cause or contribute to improper combustion. If the engine is running too hot due to a malfunctioning cooling system, detonation and preignition are much more likely to occur. A buildup of deposits in a corner of a cooling passage near the combustion chamber can have devastating effects on the engine due to detonation and preignition. The lubrication system must also reduce engine friction and heat to keep the cylinders cool enough to allow normal combustion. A restriction in the intake or exhaust system can cause the engine to misfire from a lack of air in the cylinders. If an engine cannot breathe, it cannot produce normal combustion. When the fuel system is failing to deliver adequate fuel, the engine can suffer misfire and preignition from running too hot. A lean air-fuel mixture causes hot engine temperatures; the fuel actually helps cool the mixture. If the compressed air-fuel mixture is too hot, a portion of it can autoignite either before or after the spark begins.

ENGINE NOISES The engine can create a wide variety of noises due to worn or damaged parts. It will be your job to diagnose the causes of these noises and to correct them. Most noises occur because of worn components causing excessive clearances. A typical wear item is crankshaft bearings, which cause expensive damage heard as a deep lower-end knock (Figure 5-17). Valve lifters also commonly wear with higher mileage and cause a higher pitch clatter. These are just a couple of examples of possible noises; in the Shop Manual, you will learn to isolate noises and their causes. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-17 The bearings on the left are worn down to the copper underlayer; these created engine knocking from the bottom end.

SUMMARY ■

Proper engine performance requires that the engine is mechanically sound and that its support systems are functioning as designed.

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The combustion chamber must be properly sealed to provide good engine performance. The valves, spark plug, rings, and head gasket seal the combustion chamber. The octane rating of gasoline describes its ability to resist knocking; the higher the number, the greater the resistance to knocking.

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■

■

■ ■

Higher volatility fuel should be used in the winter to assist cold starts; lower volatility fuel should be used in the summer to prevent excessive HC emissions and vapor lock. Misfire, preignition, and detonation are three types of abnormal combustion that can cause serious engine damage. Failures in the cooling or lubrication systems can cause abnormal combustion or serious engine defects. Normal engine wear will eventually lead to abnormal noises and reduced performance.

REVIEW QUESTIONS Short-Answer Essays 1. What components seal the combustion chamber? 2. What problems can occur from improper combustion chamber sealing? 3. What effect will a burned valve have on engine performance? 4. What does a gasoline’s octane rating describe? 5. What problems can occur when fuel with an inappropriate volatility is used? 6. Define preignition. 7. Define detonation. 8. Describe some causes of abnormal combustion. 9. What engine problems can detonation lead to? 10. What causes abnormal engine noises?

Fill-in-the-Blanks 1. A leak past the _______________ gasket can cause compromised engine performance. 2. The _______________ _______________, _______________ _______________, and _______________ in addition to the spark plug and cylinder wall seal the combustion chamber. 3. Malfunctions in the _______________ system and the _______________ system can cause engine mechanical problems. 4. Three types of abnormal combustion are _______________,_______________, and _______________. 5. Preignition occurs when a flame front starts _______________ the spark. 6. _______________ is likely to damage the piston.

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Factors Affecting Engine Performance

7. _______________ describes a fuel’s ability to vaporize. 8. Over _______________ timing, low _______________, and _______________ octane fuel can lead to detonation. 9. A common cause of clatter from the top end of a high-mileage engine is worn _______________. 10. Causes of engine misfire are lack of _______________ and good _______________, _______________ and _______________.

Multiple Choice 1. Fuel is generally available in octane ratings of all of the following except: C. 92 octane A. 87 octane B. 89 octane D. 99 octane 2. Normal combustion takes approximately: A. 3 milliseconds C. 2 nanoseconds B. 30 milliseconds D. 20 nanoseconds 3. Misfire means. A. the cylinder fires at the wrong time. B. the cylinder does not fire. C. two sparks occur. D. the wrong spark plug is installed. 4. Each of the following is a likely cause of detonation except: A. Carbon buildup in the combustion chamber B. Engine overheating C. A lean air-fuel mixture D. Fuel with too high of an octane rating

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6. Technician A says that worn piston rings can cause a lack of power. Technician B says that a burned valve can cause a popping noise out of the intake or exhaust. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. Spark ignition occurs: A. ATDC on the power stroke B. ATDC on the compression stroke C. ATDC on the intake stroke D. BTDC on the compression stroke 8. Technician A says that hydrocarbon emissions typically increase when an engine misfires. Technician B says that low compression can cause misfire. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. Too low a fuel volatility used in the winter will cause. A. excessive evaporative emissions. B. hard starting and rough running when cold. C. extended cranking times when the engine is hot. D. detonation. 10. A burned intake valve will cause. A. weak engine vacuum. B. lower compression pressures. C. reduced engine power. D. all of the above.

5. A _______________ informs the PCM about unusual frequency vibrations in the engine. A. coolant temperature sensor B. vibrator actuator C. knock sensor D. PCM mounting sensor

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CHAPTER 6

ENGINE MATERIALS, FASTENERS, GASKETS, AND SEALS

Upon completion and review of this chapter, you should understand and be able to describe: ■

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■

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The various types of materials used in engine construction, including iron, steel, aluminum, plastics, ceramics, and composites. The common usages of aluminum alloys in engine construction. The different manufacturing processes, including casting, forging, machining, stamping, and powdered metal. The various treatment methods, including heat treating, tempering, annealing, case hardening, and shot peening. The methods used to locate cracks in castings.

■

■ ■ ■ ■ ■ ■

How to properly identify, inspect, and select the correct fasteners required to assemble engine components to the block. The purposes of engine gaskets. The purpose of engine seals. The requirements and construction of a head gasket. The different gasket materials. The proper application of roomtemperature vulcanizing (RTV) sealant. The proper application of anaerobic sealant.

Terms To Know Aerobic sealant Alloys Anaerobic sealant Annealing Bolt diameter Bolt length Carbon steel Case hardening Ceramics Coke Composites Exhaust manifold gasket Ferrous metals Fire ring Front main seal

Gaskets Grade Grade marks Gray cast iron Intake manifold gasket Lip seal Metallurgy Nodular iron Nonferrous metals Oil pan gaskets Pitch Plastic Rear main seal Room-temperature vulcanizing (RTV)

Sealants Seals Service sleeve Shot peening Sintering Stainless steel Steel Strip seal Tempering Tensile strength Thread depth Torque-to-yield Valley pan Valve cover gasket

INTRODUCTION This chapter covers the materials and machining processes used to construct the components of the engine. Today’s technician should be able to identify these characteristics properly in order to perform repairs or machining operations on the components. 118

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Engine Materials, Fasteners, Gaskets, and Seals

The mating surfaces of the engine require proper sealing to prevent leakage and for proper engine performance. Gaskets are used to prevent gas, coolant, oil, or pressure from escaping between two stationary parts. In addition, gaskets are used as spacers, shims, wear indicators, and vibration dampers. In recent years, many gaskets have been replaced with the use of sealants. The sealant is less expensive and easy to apply. Seals are used to prevent leakage of fluids around a rotating part.

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Gaskets are used to prevent engine fluids or pressure from leaking between two stationary parts.

Seals are used to prevent leakage of fluids around a rotating part.

ENGINE MATERIALS Today’s engines are constructed with the use of several different types of materials. The same engine can have iron, steel, aluminum, plastic, ceramic, and composite components. Although a complete understanding of metallurgy is not a prerequisite for performing engine repairs, today’s technician is challenged to perform repairs requiring the proper handling, machining, and service of these materials. Metals are divided into two basic groups: ferrous metals and nonferrous metals. All metals have a grain structure that can be seen if the metal is fractured (Figure 6-1). Grain size and position determine the strength and other characteristics of the metal.

Iron Iron is a very common metal used to produce engine components. It comes from iron ore, which is retrieved from the earth. The ore is heated in blast furnaces to burn off impurities. Coke is used to fuel the furnaces, resulting in some of the carbon from the coke being deposited into the iron. When the liquid iron is poured from the coke furnace, the resultant billet (called pig iron) will have about a 5 percent carbon content. This makes the iron brittle.

Cast Iron Once the iron cools, it can be shipped for several uses. When shipped to an engine manufacturing plant, the pig iron is remelted and poured into a cast or mold. The resultant form, when the iron cools, is referred to as cast iron. During the process of remelting the iron, the amount of carbon content can be controlled, alloys can be added, or special heat treatments can be performed to achieve the desired strength and characteristics of the cast iron. The most common type of cast iron used in automotive engine construction is gray cast iron. Gray cast is easy to cast and machine. It also absorbs vibrations and resists corrosion.

Metallurgy is the science of extracting metals from their ores and refining them for various uses.

Ferrous metals contain iron. Cast iron and steel are examples of ferrous metals. These metals are easy to identify because they will naturally attract a magnet.

Nonferrous metals contain no iron. Aluminum, magnesium, and titanium are examples of nonferrous metals. These metals will not attract a magnet.

Coke is a very hotburning fuel formed when coal is heated in the absence of air. Coal becomes coke at temperatures above 1,0228F (5508C). It is produced in special coke furnaces.

Alloys are mixtures of two or more metals. For example, brass is an alloy of copper and zinc.

Figure 6-1 The properties and strength of a metal can be seen in its grain.

Gray cast iron is a type of cast iron that has a graphitic microstructure. It is a widely used material because of its tensile strength to weight ratio. A common consideration for engines because of their high-strength and lowweight requirements.

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Nodular iron, also known as ductile iron, is a version of gray cast iron but is more flexible and elastic.

Some engine applications require additional strength above that provided by gray cast. Nodular iron is used in some engines for the construction of crankshafts, camshafts, and flywheels. Nodular iron contains between 2 and 2.65 percent carbon, with small amounts of magnesium and other additives. It is also heat treated, causing the carbon to form as small balls or nodules. The result is a cast iron with reduced brittleness.

Steel

Iron containing very low carbon (between 0.05 and 1.7 percent) is called steel.

Carbon steel has a specific carbon content.

Stainless steel is an alloy that is highly resistant to rust and corrosion.

Tensile strength is the metal’s resistance to being pulled apart.

Steel is produced by heating the iron at a controlled temperature to burn off most of the carbon, phosphorus, sulfur, silicon, and manganese. As the process continues, the correct amount of carbon is then readded. This type of steel is referred to as carbon steel. Low-carbon steel (carbon content between 0.05 and 0.30 percent) can be easily bent and formed. As the carbon content of the steel increases, so does its resistance to denting and penetration. However, the higher the carbon content, the more brittle the steel. Medium-carbon steel (carbon content between 0.30 and 0.60 percent) is used for connecting rods, crankshafts, and camshafts in some engines. It is commonly used in highperformance and race engines. High-carbon steel (carbon content between 0.70 and 1.70 percent) has limited use in engine applications but is used to make drill bits, files, hammers, and other tools. The quality of steel can be improved through the addition of alloys. Some of the most common alloys include nickel, molybdenum, tungsten, vanadium, silicon, manganese, and chromium. Steel with 11 to 26 percent content of chromium is referred to as stainless steel. Nickel is often added to make the steel able to withstand sudden shock loads. If increased tensile strength is required, vanadium can be added. The addition of chromium and molybdenum (sometimes called chrome-moly) produces a very strong steel. This alloy is often used to make crankshafts in high-performance engines. Chrome-moly is also used in the construction of tube frames used in racing cars.

Magnesium Magnesium is a very lightweight metal, about two-thirds the weight of aluminum. Pure magnesium is expensive and has a low tensile strength; however, it can be alloyed with other metals (such as aluminum). Magnesium alloy is used in some engine valve, covers, or in the case of the Porsche 911, the engine block.

Aluminum Aluminum is a silver-white ductile metallic element. It is the most abundant metal in the earth’s crust. There is no pure aluminum found in the earth, though. It is always mixed with other elements. The aluminum we use comes from an ore called bauxite, containing 50 percent alumina (aluminum oxide). The bauxite is crushed and then ground into a fine powder. Then the impurities are separated from the powdered ore by mixing it with a hot caustic soda solution. It is then pumped into large pressure tanks called digesters. The temperature in the tanks, which is maintained at 3008F (1498C), dissolves the alumina, but the impurities remain solid. The impurities can then be filtered out. The remaining liquid is pumped into precipitator tanks, where it is allowed to cool slowly. The alumina comes out of the liquid as crystals when it cools. The crystals are then heated until white hot to remove any water. The result is a dry, white powder. To complete the process of turning alumina into aluminum, it is dissolved in a substance called cryolite. An electric current is passed through the pot containing the mixture from carbon anodes that hang in the liquid from overhead bars. The current flows through the liquid and causes the liquid to break up. Pure aluminum then falls to the bottom of the pot. Although aluminum is not as strong as steel, it weighs about one-third less than steel. Pure aluminum is not strong enough to be used for most engine applications, but the Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 6-2 This is a lightweight piston used in a racing engine.

attractiveness of weight reduction has led to the development of many types of aluminum alloys that are proving acceptable. Today, most pistons used in automotive engines are constructed of aluminum alloys. The light weight of aluminum pistons allows for higher engine speed and increased engine responsiveness. The lighter pistons also reduce the amount of load on the connecting rods and crankshaft (Figure 6-2). A few racing applications use aluminum connecting rods to reduce the amount of reciprocating weight. This allows the engine to accelerate faster, operate smoother, last longer, and have an increased maximum speed (also known as the red line on the tachometer). Many manufacturers are now using aluminum alloys for engine block construction. Aluminum is too soft to be used by itself and is unable to withstand the wear caused by the piston rings traveling in the cylinder. Most aluminum blocks of today’s engines are either fitted with special cylinder liners (made of iron, steel, or composite) or special casting. A few engines have used plated aluminum cylinders in the past. Most manufacturers use an aluminum alloy to construct cylinder heads, engine mounts, water pump housings, air-conditioning generator housings, intake manifolds, and valve covers. The Audi A8 was the first production vehicle to use an all-aluminum body. The higher cost of making components with aluminum has increased the basic cost of a vehicle, but has made it more fuel efficient.

Titanium Titanium alloys offer the benefits of light weight and high strength. Titanium alloys are almost as strong as steel, at about half the weight. The most common use for titanium is in racing applications for the construction of connecting rods and valves. The high cost of titanium alloys, coupled with their difficulty in being welded and machined, have limited titanium use in production vehicles. However, the NSX from Acura was introduced in 1990 with titanium connecting rods.

Plastics Plastic is a substance made from petroleum by a special method that joins atoms together to make long chains of atoms. The word plastic means something that can be pressed into a new shape. After pure plastic is made, it can be improved by adding other materials to give it additional strength, stiffness, or density.

Plastics are made from petroleum and are used in several engine components because of their light weight and heat transfer properties.

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Figure 6-3 A plastic intake manifold used on a late-model engine.

Composites are humanmade materials using two or more different components tightly bound together. The result is a material that has characteristics that neither component possesses on its own.

Plastics were first introduced in the automotive engine when American Motors used plastic to make valve covers on their 258 CID 6-cylinder engine. In subsequent years, other manufacturers have used plastics to help reduce the overall weight of the engine. Today some manufacturers are using forms of plastics to make intake manifolds, pulleys, oil pans, and valve timing train covers. Plastic intake manifolds transfer less heat to the intake air compared to cast iron or aluminum intake manifolds (Figure 6-3). This action reduces intake air temperature and engine detonation. In many cases, plastic components are easier to make production modifications in the middle of a production year. Plastics also do not transfer noise and vibration as much as metals making them quieter.

Composites Manufacturers are experimenting with increased use of composite materials. These human-made materials are showing great promise in engine applications. Graphitereinforced fiber or nylon materials have been successfully used as connecting rods, pushrods, rocker arms, intake manifolds, and cylinder liners.

Ceramics Ceramics is a combination of nonmetallic powdered materials fired in special kilns. The end product is a new product.

Ceramics also show good promise in automotive engine uses. They are lightweight, provide good frictional reduction, are heat resistant, isolate sound and vibrations, and are brittle. Engine components constructed from ceramics require special handling due to being so brittle. Ceramic components that are in use today include the compressor and turbine wheels of some General Motors turbochargers and the rocker arm pads on some Mitsubishi engines. In addition, the aftermarket parts suppliers are making ceramic valves, valve seats, valve spring retainers, and wrist pins available. Typical uses of ceramics today also include the rotor of some turbochargers, the liner for exhaust ports, intake and exhaust valves, valve seats, and piston pins.

MANUFACTURING PROCESSES Not only do different types of irons, steels, and aluminum have different qualities, the manufacturing process also determines their strength and properties. The most common processes are casting, forging, machining, and stamping. In addition to the manufacturing process, the material may be specially treated to increase strength.

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Engine Materials, Fasteners, Gaskets, and Seals

Casting As discussed earlier, casting requires heating the metal to a liquid and then pouring it into a mold. When the metal cools, it returns to a solid state. The molds can be made of foundry sand. After the metal cools, the sand is broken away to expose the part. The mold is made by packing the foundry sand around a wooden pattern. The pattern is removed prior to the liquid metal being poured in. This type of casting usually leaves a rough, grainy appearance. The lost foam casting method incorporates the use of a polystyrene foam pattern. This pattern is left in the mold when the molten metal is poured in. The heat of the molten metal vaporizes the foam. This method leaves the casting with a surface texture similar to Styrofoam (Figure 6-4). Cast iron is commonly used for engine block, camshaft, connecting rod, and crankshaft construction. Aluminum is usually cast into permanent, reusable molds. The molten aluminum alloys are forced into the mold under pressure or through the use of centrifugal force. The pressure is used to help eliminate any air pockets that may affect the machining process. Cast aluminum is commonly used for cylinder head, bell housing, piston, and intake manifold construction.

Forging Forging heats the metal to a state in which it can be worked and reshaped. It is not heated until it becomes a liquid, as it is when casting. When the metal is hot enough to be worked, a forging die is forced onto the metal under great pressure. The metal then assumes the shape of the forging die. If the metal must be worked into complex shapes, several forging dies may be used. Each die will alter the shape until the desired results are obtained. When the forging die is closed around the hot metal, some of the metal is forced into the parting lines of the die. This excess metal is called flash and is usually removed after the part is removed from the die.

Figure 6-4 This engine is formed by lost foam casting and has a surface appearance similar to Styrofoam.

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Forged parts are very strong because the high pressure used to force the die onto the component causes the grain structure to follow the shape of the part. The pressure also causes the molecules of the metal to become very compact and tightly bound. Most engines equipped with turbochargers use forged pistons, and some use forged connecting rods and crankshafts. High-performance engines often use a forged crankshaft and camshaft to increase the endurance of the engine.

Machining To construct a component from a piece of steel or iron billet is very time consuming and very expensive. Despite this, many engine components are constructed in this manner. Machined components are stronger than cast, but not as strong as forged. Machined components used in today’s engines include rocker arms, piston pins, lifters, and followers. High-performance engines use machined steel crankshafts and camshafts.

Stamping Some engine components of simple design, and not requiring much thickness, can be stamped out of a sheet of metal. The metal is not heated during this process. Depending on the final design of the component, it can be stamped on a press punch. This process is used if the piece is to remain flat. The punch is in the shape of the piece to be cut. The press forces the punch through the sheet of metal, much like a cookie cutter through dough. If the finished product must have some bends to it, it is bent by the stamping process and then trimmed to final specifications. Common components made from stamped steel include oil pans, valve covers, timing train covers, and heat shields.

Powder Metallurgy

Powder metallurgy is the manufacturing of metal parts by compacting and sintering metal powders. Sintering is done by heating the metal to a temperature below its melting point in a controlled atmosphere. The metal is then pressed to increase its density.

In tempering, metal is heated to a specific temperature to reduce the brittleness of hardened carbon steel.

Metal powder may be derived by cooling melted metal very quickly. Other methods include reducing the metal oxide, electrolysis, and crushing. The powder can then be blended with other metals to produce an alloy. The powder is then poured into a die and compacted by a cold press. Next a process of sintering is used to make the powder bond together. This process is currently being used to construct some connecting rods and valve seats. After the connecting rod is removed from the die, it is forged into final shape and then shot peened to increase its strength. This process provides a strong component at a light weight. It also eliminates many of the machining processes forged or machined connecting rods must undergo.

Treatment Methods To obtain the desired result of the component, engine manufacturers may have the component treated by heat, chemical, or shot-peening processes. Heating the metal will change its grain structure. By heat treating a metal component, its properties can be altered. To heat treat a metal properly, it is heated to a desired temperature, depending on the metal used and the desired results. Once the temperature is reached, it is maintained for a specific amount of time. The last step is to cool the metal at a controlled rate. To harden carbon steel, it is heated to 1, 4008F (7608C) and then quickly cooled. Heating the steel causes its grain structure to become finer. When it is cooled very fast, the grain structure does not have time to change and it remains very fine. The harder the steel becomes, the more brittle it becomes. To counteract the effects of hardening steel, tempering of the metal may be the next step. The steel is heated to a temperature between 3008F and 1,1008F (1508C and 6008C) and then cooled slowly. The higher the temperature used to temper the steel, the more hardening is lost, yet the toughness of the metal is increased.

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Engine Materials, Fasteners, Gaskets, and Seals

Hard metals must be softened to be machined. This process is called annealing. Annealing is much like tempering except the temperatures are increased to above 1,0008F (5508C). The metal is then allowed to cool at a slower rate than used for tempering. This makes the grain structure of the metal coarse. If desired, the metal can be hardened and tempered again after the machining process is completed. To help protect the shell or outer surfaces of a component, the manufacturer may require it to be case hardened. This process does not alter the core structure of the metal. Case hardening is performed after all machining processes are completed. Case hardening of crankshafts protects the journals from wear and fractures. Most manufacturers now use a process called ion nitriding to case harden their components. The component is placed into a pressurized chamber filled with hydrogen and nitrogen gases. An electrical current is then applied through the component. This changes the molecular structure and allows the induction of gases onto the surface area of the component. Another form of metal treatment is shot peening. Shot peening is performed by blasting the component’s surface with steel or glass shot. When the balls hit the component, a small dent is made. Thousands of these dents are applied to the component’s surface. The dents overlap each other and compress the component’s surface. This process of prestressing means any tension forces applied to the part must overcome the compression forces before the part will crack.

125

Annealing is a heattreatment process to reduce metal hardness or brittleness, relieve stresses, improve machinability, or facilitate cold working of the metal.

Case hardening is a heating and cooling process for hardening metal. Because the case hardening is only on the surface of the component, it is usually removed during machining procedures performed at the time the engine is being rebuilt. It is not necessary to replace the case hardening in most applications.

Cracks Cracks are the result of stress in the casting. A crack can cause fluid or compression leakage. When performing engine service requiring the removal of the intake manifold, exhaust manifold, cylinder heads, and so on, check the component for cracks. The following is a list of some of the most common causes for this stress: 1. 2. 3. 4. 5. 6. 7. 8.

Shot peening is a cold-working process used to make the outer layers of a metal more compressive.

Fatigue Excessive flexing Impact damage Extreme temperature changes in a very short time Freezing of the engine coolant Excessive overheating Detonation Defects during the casting process

AUTHOR’S NOTE It has been my experience that one of the common causes of cracked cylinder heads is adding cold water to the cooling system on an overheated engine. This action subjects the cylinder head to a very sudden change in temperature, resulting in a cracked head. If the engine overheats, do not loosen the radiator cap, and do not add cold water or antifreeze to the cooling system until the engine cools down.

Detecting Cracks Many cracks are detected by a thorough visual inspection. However, very small stress cracks may not be detected in this manner. There are several different methods of crack detection. Following is a sample of the four most common methods: 1. Magnetic particle inspection (MPI). Uses an electromagnet to create a magnetic field in the casting (Figure 6-5). Because all magnets have north and south poles, the magnetic field runs from one pole to the other through the casting. A crack in Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 6

N

Figure 6-5 This damaged racing crankshaft is being magnafluxed to check for cracks.

Magnaflux is another name for magnetic particle inspection.

S

N

S

Figure 6-6 A crack causes a break in the magnetic field, creating opposite magnetic poles.

the casting causes a break in the field, creating opposite poles (Figure 6-6). The magnetic powder is attracted to this area. Magnetic particle inspection cannot be used to detect cracks in aluminum parts because they cannot be magnetized. 2. Magnetic fluorescent. This method uses a fluorescent paste dripped onto the casting. The casting is then placed in a magnetic field and observed under a black light. Cracks are visible by white, gray, or yellow streaks. 3. Penetrant dye. Using dye penetrant is a three-step process. First, the special dye is sprayed onto the casting surface and allowed to dry. The excess dye is then wiped away. Next, a special remover is sprayed over the surface and the casting is rinsed with water. Third, the developer is sprayed onto the casting. As it dries, any dye left in the cracks seeps through the developer. The crack shows as a red line against a white background. 4. Pressurizing the block or head. The casting can be pressurized with air or water. When air is used, the casting is attached to a special fixture and 40–60 psi of air pressure is applied. A soapy solution is then sprayed onto the casting so the technician can look for bubbles, indicating a leak. Water pressure testing uses hot water to cause casting expansion. If the casting is leaking, water will be found on the outside of it.

FASTENERS There are many different types of fasteners used throughout the engine. The most common are threaded fasteners, including bolts, studs, screws, and nuts. These fasteners must be inspected for thread damage, fillet damage, and stretch before they can be reused (Figure 6-7). Some bolts stretch in different areas than that shown in Figure 6-7. Some manufacturers require that you measure the diameter of the bolt’s shank to determine if it can be reused. Other manufacturers may call for the measurement of bolt length to inspect for excessive bolt stretch. In addition, many threaded fasteners are not designed for reuse; the service manual should be referenced for the manufacturer’s recommendations. If a threaded fastener requires replacement, there are some concerns the technician must be aware of: ■ Select a fastener of the same diameter, thread pitch, strength, and shank length as well as overall length as the original. ■ Note that all bolts in the same connection must be of the same grade. ■ Use nut grades that match their respective bolts. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Materials, Fasteners, Gaskets, and Seals

127

Unstretched bolt Wrench pad

Shank

Threads

Threads are straight on line

Stretched bolt

Fillet Threads are not straight on line

Figure 6-7 Check all bolts for stretch and other damage before reusing them.

Washer face

Figure 6-8 A typical bolt.

Use the correct washers and pins as originally equipped. Torque the fasteners to the specified value. ■ Use torque-to-yield bolts where specified. Standard threaded fasteners used in automotive applications are classified by the Unified National Series using four basic categories: ■ ■

1. 2. 3. 4.

Unified National Coarse (UNC or NC) Unified National Fine (UNF or NF) Unified National Extrafine (UNEF or NEF) Unified National Pipe Thread (UNPT or NPT)

In recent years, the automotive industry has switched to the use of metric fasteners. Metric threads are classified as coarse or fine, as denoted by an SI or ISO lettering. The most common type of threaded fastener used on the engine is the bolt (Figure 6-8). To understand proper selection of a fastener, terminology must be defined (Figure 6-9). The head of the bolt is used to torque the fastener. Several head designs are used, including hex, torx, slot, and spline. Bolt diameter is the measure across the threaded area or shank. The pitch (used in the English system) is the number of threads per inch. In the metric system, thread pitch is a measure of the distance (in millimeters) between two adjacent threads. Bolt length is the distance from the bottom of the head to the end of the bolt. The grade of the bolt denotes its strength and is used to designate the amount of stress the bolt can withstand. The grade of the bolt depends upon the material it is constructed from, bolt diameter, and thread depth. Grade marks are placed on the top of the head (in the English system) to identify the bolt’s strength (Figure 6-10). In the metric system, the strength of the bolt is identified by a property class number on the head (Figure 6-11): the larger the number, the greater the tensile strength. Like bolts, nuts are graded according to their tensile strength (Figure 6-12). As discussed earlier, the nut grade must be matched to the bolt grade. The strength of the connection is only as strong as the lowest grade used; for example, if a grade 8 bolt is used with a grade 5 nut, the connection is only a grade 5. Proper fastener torque is important to prevent thread damage and to provide the correct clamping forces. The service manual provides the manufacturer’s recommended torque value and tightening sequence for most fasteners used in the engine. The amount of torque a fastener can withstand is based on its tensile strength (Figure 6-13). To obtain proper torque, the fastener’s threads must be cleaned and may require light lubrication. Always clean out bolt holes before installing the bolts. Parts can crack from hydrostatic pressure if a bolt is installed in a threaded hole with fluid in it.

Unified National Fine-thread or Unified National Course thread bolts may be referred to as fine-thread or coarsethread bolts.

Bolt diameter indicates the diameter of an imaginary line running through the center of the bolt threaded area. Pitch is the number of threads per inch on a bolt in the USC system.

Bolt length indicates the distance from the underside of the bolt head to the tip of the bolt threaded end.

The grade of a bolt is the classification of its strength.

Thread depth is the height of the thread from its base to the top of its peak.

Grade marks are radial lines on the bolt head.

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128

Chapter 6 T H D

G

L H = HEAD G = GRADE MARKETING (BOLT STRENGTH) L = LENGTH (INCHES) T = THREAD PITCH (THREAD/INCH) D = NORMAL DIAMETER (INCHES) A T H D

P

L H = HEAD G = PROPERTY CLASS (BOLT STRENGTH) L = LENGTH (MILLIMETERS) T = THREAD PITCH (THREAD/MILLIMETER) D = NORMAL DIAMETER (MILLIMETER)

−9.8

B

Figure 6-9 Bolt terminology.

SAE grade markings Definition

No lines: unmarked indeterminate quality SAE grades 0-1-2

3 lines: common commercial quality Automotive and AN bolts SAE grade 5

4 lines: medium commercial quality Automotive and AN bolts SAE grade 6

5 lines: rarely used SAE grade 7

6 lines: best commercial quality NAS and aircraft screws SAE grade 8

Material

Low-carbon steel

Medium-carbon steel tempered

Medium-carbon steel quenched and tempered

Medium-carbon alloy steel

Medium-carbon alloy steel quenched and tempered

Tensile strength

65,000 psi

120,000 psi

140,000 psi

140,000 psi

150,000 psi

Figure 6-10 Bolt-grade identification marks.

Torque-to-Yield Modern engines are designed with very close tolerances. These tolerances require an equal amount of clamping forces at mating surfaces. Normal head bolt torque values have a calculated 25 percent safety factor; that is, they are torqued to only 75 percent of the bolt’s Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Materials, Fasteners, Gaskets, and Seals

4.6

4.8

5.8

Class 10.9

8.8

9.8

Class 9.8

10.9

Class 8.8

Figure 6-11 Property class numbers.

Inch system Grade

Metric system Identification

Class

Identification

Hex nut property grade 9

Hex nut grade 5

9 Arabic 9

3 dots Hex nut property grade 10

Hex nut grade 8

10

6 dots

Arabic 10

Increasing dots represent increasing strength.

Can also have blue finish or paint dab on hex flat. Increasing numbers represent increasing strength.

Figure 6-12 Nut grade markings.

STANDARD BOLT AND NUT TORQUE SPECIFICATIONS Size Nut or Bolt

Torque ft-Ib

Size Nut or Bolt

Torque ft-Ib

Size Nut or Bolt

Torque ft-Ib

1/4–20 1/4–28 5/16–18 5/16–24 3/8–16 3/8–24 7/16–14

7–9 8–10 13–17 15–19 30–35 35–39 46–50

7/16–20 1/2–13 1/2–20 9/16–12 9/16–18 5/8–11 5/8–18

57–61 71–75 83–93 90–100 107–117 137–147 168–178

3/4–10 3/4–16 7/8–9 7/8–14 1–8 1–14

240–250 290–300 410–420 475–485 580–590 685–695

Figure 6-13 Standard bolt and nut torque specifications.

maximum proof load (Figure 6-14). Using the chart, it can be seen that a small difference between torque values at the bolt head can result in a large difference in clamping forces. Because torque is actually force used to turn a fastener against friction, the actual clamping forces can vary even at the same torque value. Up to about 25 ft-lb (35 Nm) of torque, the clamping force is fairly constant; however, above this point, variation of actual Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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130

Chapter 6

Grade of Bolt

SD

Minimum Tensile Strength (Psi)

71,160

Grade Marking on Head

SD

BC

10K

12K

113,800 142,000 170,674

BC

10K

12K

Socket or Wrench Size Metric

Metric

TORQUE (In Foot Pounds)

Bolt Diameter (mm)

Bolt Head (mm)

Nut (mm)

6

5

6

8

10

10

10

8

10

16

22

27

14

14

10

19

31

40

49

17

17

12

34

54

70

86

19

19

14

55

89

117

137

22

22

16

83

132

175

208

24

24

18

111

182

236

283

27

27

22

182

284

394

464

32

32

24

261

419

570

689

36

36

Figure 6-14 Metric bolt and nut torque specifications.

Torque-to-yield is a stretch-type bolt that must be tightened to a specific torque and then rotated a certain number of degrees.

clamping forces at the same torque value can be as high as 200 percent. This is due to variations in thread conditions or dirt and oil in some threads. Up to 90 percent of the torque is used up by friction, leaving 10 percent for the actual clamping. The result could be that some bolts have to provide more clamping force than others, distorting the cylinder bores. For this reason only lubricate a fastener’s threads if the vehicle manufacturer recommends doing so. To compensate and correct for these factors, many manufacturers use torque-toyield bolts. The yield point of identical bolts does not vary much. A bolt that has been torqued to its yield point can be rotated an additional amount without any increase in clamping force. When a set of torque-to-yield fasteners is used, the torque is actually set to a point above the yield point of the bolt. This ensures that the set of fasteners will have an even clamping force. Manufacturers vary on specifications and procedures for securing torque-to-yield bolts. Always refer to the service manual for exact procedures. In most instances, first a torque wrench is used to tighten the bolts to their yield point. Next, the bolt is turned an additional amount as specified in the service manual. The graph in Figure 6-15 indicates that a bolt can be elongated considerably at its yield point before it reaches its failure point. Also notice that the clamp load is consistent between the proof load and the failure point of the bolt. Bolts that are torqued to their yield points have been stretched beyond their elastic limit and require replacement whenever they are removed or loosened.

Liquid Thread Lockers Thread lockers are used to keep fasteners from loosening due to vibration or torsional twisting. They are commonly anaerobic, meaning they won’t cure in the outside air but will cure between fastener threads in the absence of air. Liquid thread lockers come in Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Materials, Fasteners, Gaskets, and Seals

Elastic range

Caution

Plastic range

Ultimate tensile strength

Proof load Clamp load (lbs)

131

Yield point

Failure point

Normal torque (75% of proof load)

Bolt elongation (in.)

Figure 6-15 Relationship between proper clamp load and bolt failure.

If a torque procedure includes rotation of the bolt a certain number of degrees after the final torque, it is a torque-to-yield bolt. Most manufacturers require replacement of torque-to-yield bolts after one use, although some manufacturers allow a specified number of reuses. Always check the service information specific to the vehicle you are working on.

different grades or strengths. “High strength” means heat is needed to break the “lock” on the fastener to take it back apart. Common engine bolts using thread locker are crankshaft pulley, flywheel, and camshaft bolts. See service information to determine which fasteners require locking compound.

GASKETS, SEALS, SEALANTS, AND ADHESIVES Gaskets There are three basic engine gasket classifications (Figure 6-16): 1. Hard gaskets. These include gaskets made of metals or metals covering a layer of clay/fiber compound. Head gaskets, exhaust manifold, intake manifold, and exhaust gas recirculation (EGR) valve gaskets are examples of this type of gasket. 2. Soft gaskets. These gaskets are made of rubber, cork, paper, and rubber-covered metal. Common usages include valve covers, oil pans, thermostat housings, water pumps, timing covers, and some intake manifolds. 3. Liquid gasket makers. These are usually a type of liquid material used to form gaskets. Silicones and anaerobics are examples of liquid gasket makers. Cylinder Head Gaskets. Perhaps the cylinder head gasket is subjected to the greatest demands. It must be capable of sealing combustion pressures up to 2,700 psi (18,616 kPa) and withstanding temperatures over 2,0008F (1,1008 C). In addition, it must be able to seal coolant and oil under pressure. To complicate the matter further, the head gasket must be able to perform these functions while accommodating a shearing action resulting from expansion rates of the metals. Shearing results from the difference in thermal expansion between the cylinder head and the block. As the two metals expand and contract at different rates and amounts, a scrubbing stress is created (Figure 6-17). The head gasket cannot move during these times. A large factor in determining what type of head gasket to use in a specific engine is the metals the head and the block are constructed from. The head and the block deck surface finish is mostly determined by what type of head gasket is being used. Changing the head gasket design without surface finish consideration can lead to early gasket failure. The head gasket consists of a core, facing, and coating. The core is usually made from solid or clinched steel. The facing is usually constructed of graphite and rubber fiber. These materials allow sufficient compression to conform to minor surface irregularities. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 6 Intake manifold

Gasket

Gasket Gasket

Gasket Delivery pipe

Cold start injector pipe

Adjusting shim Valve filter Valve keepers Valve spring retainer

Cylinder head cover

Valve spring

Gasket

Valve stem oil seal Spring seat Spark plug tube seal Valve guide bushing Camshaft subgear Exhaust camshaft

Camshaft bearing cap

Valve

Snap ring

Water inlet housing Intake camshaft

Distributor

Cylinder head

Wave ring Camshaft gear spring

Oil seal

Water outer pipe

Fan belt adjusting bar

Gasket Gasket

Manifold heat insulator (upper)

Exhaust manifold Manifold heat insulator (lower)

Figure 6-16 Seals and gaskets are located at critical seal points within the engine.

The coating may be Teflon or silicone based and works with the facing to seal minor surface irregularities and resist shearing. Some head gaskets use an elastomeric sealing bead to increase clamping forces around fluid passages (Figure 6-18). One of the most recent developments in head gaskets is rubber-coated embossed (RCE) steel shim gaskets. A rubber coating is bonded to a steel shim gasket. The coating protects the shim from corrosive elements in the cooling and lubrication systems and Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Materials, Fasteners, Gaskets, and Seals

Aluminum head expands more

Aluminum head expands more Typical gasket

Cast-iron block expands less

133

Soft, thick gasket moves with both

Coated gasket

Cast-iron block expands less

Anti-stick coating allows different movement

Figure 6-17 The coating on the gasket material allows for different expansion rates between metals and still provides a good seal without distorting the gasket.

Composite facing material Elastomeric sealing bead Stainless steel fire ring Solid steel core

Figure 6-18 Sealing beads work to prevent fluid leakage.

provides good friction reduction. Because of their construction, RCE gaskets are also referred to as multilayer steel (MLS) gaskets. There are many advantages to the multilayer design. First, it has a uniform thickness that prevents bore distortion during cylinder head installation. Also, the MLS gasket is very resilient in that once compressed, it “bounces” back for a good seal. Most cylinder head gaskets have a metal fire ring around the combustion chamber opening (Figure 6-19). The fire ring protects the gasket material from the high temperature it is exposed to. Also, the fire ring increases the gasket thickness around the cylinder bore so that it uses up to 75 percent of the clamping force to form a tight seal against combustion pressure losses. Intake Manifold Gaskets. A leak in the connection of the intake manifold and cylinder head creates a vacuum leak that allows unmeasured air into the engine. This can cause the mixture entering the combustion chamber to be too lean (not enough fuel), resulting in rough idle, detonation, or both. The intake manifold gasket is designed to provide a good seal under the changing temperatures it will be subject to (Figure 6-20). Many intake manifold gaskets are constructed of a solid or perforated steel core with a fiber facing. Some manufacturers use gaskets made from a rubber silicone bonded to steel or high-temperature plastic. On this style, the silicone provides the actual sealing. Some V-type engines use a valley pan style of intake manifold gasket. In addition, V-type engines use end strip seals to seal the connection between the ends of the manifold and the block. Strip seals are generally made from molded rubber or cork-rubber. Many fuelinjected engines use a plenum that requires a gasket between it and the intake manifold (Figure 6-21). With the advancement of plastics and composites, some manufacturers are designing intake manifolds from these products. Some of these do not use the typical intake manifold gasket; instead, they use a series of O-rings to seal each port (Figure 6-22).

A fire ring is a metal ring surrounding the cylinder opening in a head gasket.

The intake manifold gasket fits between the manifold and cylinder head to seal the air-fuel mixture or intake air.

Valley pans prevent the formation of deposits on the underside of the intake manifold.

A strip seal provides a seal between the flat surfaces on the front and back of the engine block and the intake manifold.

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Chapter 6

Figure 6-19 This head gasket has a sealing bead and fire rings around the cylinders.

Sealer

Intake plenum

Intake manifold gaskets

Gasket Engine manifold

Figure 6-20 Intake manifold gasket location.

Figure 6-21 Intake plenum gasket location.

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Engine Materials, Fasteners, Gaskets, and Seals

135

Intake manifold

Captive O-ring seals

Figure 6-22 Some intake manifolds use captive O-rings to seal against the cylinder head.

Exhaust Manifold Gaskets. The exhaust manifold gasket must prevent leakage under extreme temperatures (Figure 6-23). Leaks in this connection disrupt the flow of exhaust gases and can result in poor engine performance. In addition, exhaust leaks can lead to burned valves and objectionable noises. The use of exhaust manifold gaskets by engine manufacturers has declined in recent years with improved machining processes and better materials; however, when the exhaust manifold is removed, it may become warped and require the use of a gasket. Most technicians opt to install an exhaust manifold gasket even if the engine was not originally equipped with one. Valve Cover Gaskets. Valve cover gaskets are common locations for external oil leakage. This is largely due to the wide spacing between the attaching bolts. The wide spacing allows the stamped steel cover to distort easily and provides less clamping forces (Figure 6-24). To seal properly, the valve cover gasket must be highly compressible yet have good torque retention. To perform these tasks, a variety of materials are used to construct valve cover gaskets. Some of the most common are synthetic rubber, cork-rubber, and molded rubber. Synthetic rubber gaskets seal by deforming instead of compressing. The synthetic rubber has a tendency to “remember” its original shape and will attempt to return to it. When the valve cover is tightened against the gasket, the gasket deforms. The gasket attempts to return to its original shape and pushes back against the valve cover, creating a

The exhaust manifold gasket seals the connection between the cylinder head and the exhaust manifold.

Valve cover gaskets seal the connection between the valve cover and the cylinder head. The gasket is not subject to pressures, but must be able to seal hot, thinning oil.

Valve covers may be called rocker arm covers.

Exhaust manifold gasket Exhaust manifold

Area of less clamping force

Valve cover flange

Valve cover gasket Cylinder head

Figure 6-23 Exhaust manifold gasket location.

Figure 6-24 The valve cover gasket can easily be deformed.

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Chapter 6

tight seal. One drawback to this gasket is it can be difficult to install. Cork-rubber gaskets compress very well and provide good sealing. Molded rubber gaskets are the easiest to install and provide the best sealing. Sealers or adhesives should not be used on molded rubber gaskets. In addition to the valve cover gasket, many overhead camshaft engines use molded rubber semicircular plugs (Figure 6-25). Oil pan gaskets are used to prevent leakage from the crankcase at the connection between the oil pan and the engine block.

Oil Pan Gaskets. Oil pan gaskets can be multipiece or a single-unit molded gasket, depending on the crankcase design. The most common type of multipiece gasket uses two side pieces made of cork and rubber and two end pieces made of synthetic rubber (Figure 6-26). Many modern engines use a single-unit molded gasket (Figure 6-27). Miscellaneous Gaskets. Many additional gaskets are used on the engine. Each of these must be replaced during the assembling process. Additional gasket applications include the following: ■ Exhaust gas recirculation (EGR) valve ■ Water pump

Semicircular plugs Oil pan gasket

Figure 6-25 Camshaft plugs work with the valve cover gasket to seal oil.

Oil pan

Figure 6-26 Multipiece oil pan gasket.

Figure 6-27 A one-piece oil pan gasket. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Materials, Fasteners, Gaskets, and Seals

Air cleaner Fuel injector mounting ■ Timing cover ■ Exhaust pipe Each of these gaskets is designed for a particular purpose. The materials used must perform many of the tasks previously discussed, but under unique circumstances. Always refer to the service manual for the proper torque and sequence when installing these gaskets. ■

A front main seal is a lip-type seal that prevents leaks between the timing gear cover and the front of the crankshaft.

■

The rear main seal is a seal installed behind the rear main bearing on the rear main bearing journal to prevent oil leaks.

Seals The most common seals in the engine are the front main seal (also called the timing cover seal) and the rear main seal. The front main seal seals around the harmonic balancer to prevent oil leakage from the front of the crankshaft, while the rear main seal prevents leakage from the rear of the crankshaft. Most modern engines use a type of lip seal to perform these functions. The lip seal is generally constructed of butyl rubber or Neoprene. The rubber seal is attached to a metal case that is driven into the bore (Figure 6-28). The seal lip will use the pressure of the fluid between the seal and the case to force the lip tight against the shaft. To assist in providing a tighter seal, some lip seals use a garter spring behind the lip. If the seal is installed in a location where the front of the seal may be exposed to dirt, a dust lip may be formed into the seal to deflect dirt away from the outside of the seal. When installing a new lip seal, the lip always faces the hydraulic pressure side or the fluid side. The front main and oil pump housing oil seals are generally one-pipe lip seals with a steel outer ring (Figure 6-29). To aid in sealing during installation, apply silicone sealer to the outer diameter of the metal shell. Neoprene seals should always be lubricated prior to installation. This will prevent seal damage from overheating during initial startup. If the surface of the harmonic balancer is damaged, a service sleeve can be installed to provide a new sealing surface. There are three common seal designs for rear main seals: rope-type, two-piece molded synthetic rubber, and one-piece rubber with steel ring. The rope-type rear main seal is found on many older engines. These are difficult to replace without removing the crankshaft. They were replaced with molded two-piece seals. Rope-type seals are also two pieces. The lower piece is installed into the bearing cap, while the upper piece is installed into the block.

Lip seals are formed from synthetic rubber and have a slight raise (lip) that is the actual sealing point. The lip provides a positive seal while allowing for some lateral movement of the shaft.

Service sleeves (sometimes referred to as speedy-sleeves) press over the damaged sealing area to provide a new, smooth surface for the seal lip.

Spring Oil Dust lip

Lip seal Figure 6-28 The common lip seal has an outer case, rubber sealing lips, and a gator spring. Hydraulic pressure works to cause the lip seal to ride tight against the shaft.

137

Front main seal

Figure 6-29 The front main seal fits into the timing cover.

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138

Chapter 6

A BIT OF HISTORY In the year 2000, sales of light trucks surpassed car sales. The light truck market consists of these vehicles. 1. 2. 3. 4. 5. 6. 7.

Minivans—17.9 percent Full-sized vans—5.5 percent Full-sized pickups—26.6 percent Compact pickups—14.7 percent Full-sized sport-utility vehicles (SUVs)—8 percent Compact SUVs—23.3 percent Small SUVs—3.9 percent

Adhesives, Sealants, and Liquid Gasket Maker

Sealants are commonly used to fill irregularities between the gasket and its mating surface. Some sealants are designed to be used in place of a gasket.

Aerobic sealants require the presence of oxygen to cure.

Anaerobic sealants will only cure in the absence of oxygen.

Room-temperature vulcanizing (RTV) compound is a type of engine sealer that may be used in place of a gasket on some applications.

A number of chemical sealing materials are available, which are designed to reduce parts ordered or inventoried and increase the probability of a good seal. Proper use of these chemical materials is required to ensure good results. To assist in gasket material removal, spray or brush-on gasket remover solvent is available. Adhesives are designed to bond different types of gasket materials in place prior to installation. These would be used to hold the gasket in place during installation of parts that may require a lot of wiggling into place. Some gaskets must be coated with a sealer prior to installation. This is true of a few MLS cylinder head gaskets. Some sealants can damage gasket coatings: Be sure to check the instructions for the gasket you are installing. In the 1980s, many manufacturers began switching to sealants and liquid gasket makers instead of molded gaskets at many joint connections throughout the engine. When applying these materials, care must be taken to ensure proper application. Bead size, continuity, surface prep, and location are factors affecting proper sealing. If the bead is too thin, a leak can result. A bead that is too wide can result in spillover and clog the oil pump or oil galleries. Also, the manufacturer may require different types of sealers at specified locations in the engine. For this reason, always refer to the service manual for the correct type and usage of sealers. There are two basic types of sealants: ■ Aerobic ■ Anaerobic Most aerobic sealants and liquid gasket makers are silicone compounds and work well with metals and plastics. The most common type of liquid gasket maker is roomtemperature vulcanizing (RTV) compound. This type of gasket maker forms a seal by absorbing moisture from the air. RTV gasket makers are capable of filling gaps up to 0.25 in. Before attempting to use RTV, the sealing surfaces must be thoroughly cleaned. RTV begins to set in about 10 minutes, requiring the components to be assembled quickly. Some RTV suppliers use different colors to denote the temperature range the RTV is capable of withstanding. Use the correct RTC for the expected temperature. RTV cannot be used on high-temperature exhaust system components. Before using any adhesives, sealants, or liquid gasket makers on engine components, make sure the package label states “Sensor Safe.” Otherwise the O 2 sensors could end up failing and needing replacement due to silicon contamination. Anaerobic sealants and liquid gasket makers are best used between machine metal parts like transmission case halves. These liquids cure after the components have been assembled. Anaerobic gasket makers are capable of filling gaps up to 0.015 in. (0.4 mm) and withstand temperatures up to 3508F (1778C). Some engines using a one-piece main

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bearing require the use of special anaerobic sealants that do not cure until a specified temperature is reached. This ensures proper maintenance of oil clearances as the main bearing bolts are torqued, without fear of the sealant setting too soon. Liquid gasket makers can also be made from elastomeric rubber. They do an excellent job of sealing for many miles. Parts that use this type of gasket maker can be a challenge to disassemble.

SUMMARY ■

■ ■ ■

■ ■

Metals are divided into two basic groups: ferrous and nonferrous. Ferrous metals are those containing iron. Nonferrous metals contain no iron. Alloys are mixtures of two or more metals. Iron containing very low carbon (between 0.05 and 1.7 percent) is called steel. Composites are human-made materials using two or more different components tightly bound together. The result is a material consisting of characteristics that neither component possesses on its own. Powder metallurgy is the manufacturing of metal parts by compacting and sintering metal powders. Metric and standard bolts are used on today’s automobiles.

■ ■ ■ ■ ■ ■

■

Gaskets are used to prevent gas, coolant, oil, or pressures from escaping between two mating parts. Seals are used to seal between a stationary part and a moving one. Sealants are used to seal parts and gaskets. Liquid gasket makers have replaced many of the gaskets on engines. Examples of sealants and liquid gasket makers are anaerobics and aerobic (RTV). Cylinder head gaskets must seal cylinder pressures up to 2,700 psi (18,616 kPa) and withstand temperatures over 2,0008F (1,1008C). Aerobic sealants require the presence of oxygen to cure. Anaerobic sealants will only cure in the absence of oxygen.

REVIEW QUESTIONS Short-Answer Essays 1. Describe the advantage of aluminum alloy engine components compared to cast iron or steel components.

10. List three different types of valve cover gaskets.

Fill-in-the-Blanks

2. List the methods available to locate cracks in castings.

1. _______________ metals are those containing iron. _______________ metals contain no iron.

3. Describe the purpose of torque-to-yield bolts.

2. _______________ _______________ is the metal’s resistance to being pulled apart.

4. Explain the bolt grade marking system. 5. Define the following terms used with bolts: Head Diameter Pitch Length Grade 6. Describe what an anaerobic sealant is. 7. What is the function of a seal?

3. _______________ is the process of heating the metal to remove its hardness. 4. Most aluminum blocks are fitted with cylinder _______________. 5. Bolt diameter is the measure across the _______________ area. 6. _______________ sealants require the presence of oxygen to cure.

8. Describe the demands that a head gasket is subjected to.

7. When installing a lip seal, the lip always faces the _______________ _______________ or _______________ side.

9. Explain the advantages of rubber-coated embossed or multilayer steel head gaskets.

8. Neoprene seals should always be _______________ before installation.

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9. Head gaskets must be able to seal _______________ and _______________ from the combustion chamber under pressure. 10. The most common lip seals used on a typical engine are the _______________ _______________ and the _______________ _______________.

Multiple Choice 1. Ceramic engine components have all these characteristics except: A. Light weight B. Heat resistance C. Non-brittleness D. Ability to isolate sound and vibration 2. Forged engine components have these advantages and applications: A. Intake manifolds may be forged. B. Crankshafts may be forged. C. Rocker arm covers may be forged. D. They provide a softer metal that is more easily machined. 3. Engine components may be cracked by: A. extreme temperature changes in a very short time. B. extremely low, uniform temperatures. C. an excessive amount of antifreeze in the coolant. D. engine operating temperature below normal. 4. The manufacturing process that yields the strongest finished part is: C. machining. A. casting. B. forging. D. stamping. 5. Each of the following statements is true except: A. Tempering increases the toughness of the metal. B. Annealing makes a metal easier to be machined. C. Sintering bonds the metal powder together. D. Case hardening makes the metal’s grain coarser.

6. When installing intake manifold gaskets: A. End strips are used to seal the ends of an OHV intake manifold to the block. B. A valley pan–type intake gasket is used on in-line engines. C. A leaking intake manifold gasket will cause a rich air-fuel mixture. D. Silicone sealer should be placed on both sides of the intake manifold gasket before installation. 7. All of these statements about head gaskets are true except: A. A conventional head gasket contains a core, facing, and coating. B. The core is usually made from silicone. C. The facing is usually made from graphite or rubber fiber. D. The coating may be made from Teflon. 8. The fire ring in a head gasket A. compensates for movement between metals with different expansion rates. B. increases heat transfer to the cooling system. C. protects the gasket material from high combustion temperatures. D. seals coolant passages through the head gasket. 9. Which of the following statements is true for replacing valve cover gaskets? A. A sealant should be used with molded rubber valve cover gaskets. B. An anaerobic sealant should be used with cork valve cover gaskets. C. The exhaust manifold and the valve cover gasket are usually made of the same material. D. Some valve cover gaskets are made from a synthetic rubber. 10. When discussing exhaust manifold connections, each of the following statements is true except: A. Some engines do not use an exhaust manifold gasket. B. Some exhaust manifolds are sealed with RTV. C. A damaged gasket can result in poor engine performance. D. An exhaust manifold gasket is a hard gasket.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 7

INTAKE AND EXHAUST SYSTEMS

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■ ■ ■ ■

The purpose of the air filter. The design of the air filter. The three different materials used to manufacture intake manifolds. The purpose of the intake manifold. The advantages of aluminum and plastic intake manifolds compared to cast iron. The operation and advantages of intake manifolds with dual runners. Two different methods for operating the valves that open and close the intake manifold runners.

■

How the engine creates vacuum.

■

How vacuum is used to operate and control many automotive devices.

■

The operation of exhaust system components, including exhaust manifold, gaskets, exhaust pipe and seal, muffler, resonator, and tailpipe, and clamps, brackets, and hangers.

■

The benefits and operation of turbochargers and superchargers.

■

The purpose and operation of the catalytic converter.

Terms To Know Air filter Airflow restriction indicator Back pressure Catalytic converter Compressor wheel Exhaust manifold Intake air temperature (IAT) sensor

Intake manifold Intercooler Mass airflow (MAF) sensor Muffler Oil coking Resonator Roots-type supercharger Supercharger

Tailpipe Turbine wheel Turbo boost Turbo lag Turbocharger Variable-length intake manifold Wastegate

INTRODUCTION It’s very simple—the better an engine can breathe, the more power it will make. The intake and exhaust system is the breathing apparatus for the engine. To maximize volumetric efficiency, the intake and exhaust manifolds must be carefully designed. Both must allow adequate airflow to provide strong engine operation. A plugged air filter can seriously restrict airflow, causing the engine to run with reduced power or even not to start. A restricted exhaust system can cause the same symptoms. The engine must be able to freely take air in and easily push air out to breathe well. The intake system must be well sealed so that a strong vacuum is formed. This ensures that air will flow into the cylinder when the throttle and intake valves are open.

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Some engines used a forced induction system to increase airflow into the engine. A turbocharger or supercharger pressurizes the air above atmospheric pressure to force more air in when the intake valves open. This improvement in volumetric efficiency can increase engine power dramatically.

AIR INDUCTION SYSTEM The intake system consists of the air inlet tube, an air filter, ducting, a throttle bore, and the intake manifold (Figure 7-1). The opening and closing of the throttle plate in the throttle bore controls airflow into the engine. Think of the throttle plate in a gasoline engine as a restrictive device that limits and controls the amount of air that will enter the engine. Some systems use a throttle cable to open and close the throttle plate, while others employ “drive by wire” technology. In these systems, the Powertrain Control Module (PCM) responds to an input from the apps (accelerator pedal position sensors) and controls a motor at the throttle plate to open it to the correct angle. The intake system should provide airflow at a high velocity and low volume when the engine is operating at low rpms. This ensures good fuel atomization and mixing when the injector sprays into the airstream in the manifold near the intake valve. The intake system should deliver a high volume of air when the engine is running at high rpms, to fill the combustion chamber as much as possible in a short time. This keeps power output high even at higher engine speeds. Volumetric efficiency will naturally fall at higher rpms, but the design of the intake and exhaust systems can reduce the losses. The intake system pulls in fresh air from outside the engine compartment. Ducts direct this air through the air filter and into the throttle body assembly to power the engine. The air filter is placed below the top of the engine to allow for aerodynamic body designs. Electronic sensors measure airflow, temperature, and density. The air induction system performs the following functions: ■ Filters the air to protect the engine from wear ■ Silences air intake noise ■ Heats or cools the air as required ■ Provides the air the engine needs to operate ■ Monitors airflow temperature and density for more efficient combustion and a reduction of hydrocarbon (HC) and carbon monoxide (CO) emissions ■ Operates with the positive crankcase ventilation (PCV) system to burn the crankcase fumes in the engine

Throttle body

Intake duct

Throttle position sensor

Air-flow sensor

Air cleaner assembly Resonator

Air temperature sensor

Figure 7-1 A late-model intake air distribution system. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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AIR INTAKE DUCTWORK Ductwork is used to direct the air into the throttle body. Cool outside air is drawn into the air cleaner assembly, and on some engines, warm air from around the exhaust is also brought in for cold engine operation. Many air ducts include a resonator chamber that looks like an irregularly shaped protrusion on the side of an intake duct. This is used to reduce the rumble of intake air as it rushes through the ductwork. Air then flows through the air filter, where particulate matter that could damage the engine is removed. Another leg of ducting connects the air filter housing to the throttle bore. Many vehicles have a mass airflow (MAF) sensor in this ducting to measure the mass of air flowing into the engine. Most engines also use an intake air temperature (IAT) sensor in the air cleaner housing of intake ductwork (Figure 7-2). As the air temperature increases, the air density decreases. The PCM will reduce the amount of fuel delivered, as needed to ensure excellent fuel economy and low emissions. Be sure that the intake ductwork is properly installed and all connections are airtight, especially those between the MAF sensor or remote air cleaner and the throttle plate assembly. If outside air can sneak in through a leak in the ductwork, it is not filtered. Vehicles that use a MAF sensor measure the air coming into the engine from the air filter. The PCM uses this input as the primary indicator of how much fuel should be injected. If air is drawn into the engine beyond the MAF sensor through a leak in the duct, it will not be measured. The PCM will deliver less fuel, and the engine will run too lean. Generally, metal or plastic air ducts are used when engine heat is not a problem. Special paper/metal ducts are used when they will be exposed to high engine temperatures.

The mass airflow (MAF) sensor measures the mass of airflow entering the engine and sends an input to the PCM reflecting this value. This is a primary input for the PCM’s control of fuel delivery.

AIR CLEANER/FILTER The primary function of the air filter is to prevent airborne contaminants and abrasives from entering the engine. Without proper filtration, these contaminants can cause serious damage and appreciably shorten engine life. All incoming air should pass through the filter element before entering the engine (Figure 7-3).

The air filter prevents dirt from entering the engine.

Intake Air Temperature Sensor

Figure 7-2 The intake air temperature sensor helps the PCM determine the correct fuel delivery and spark timing. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Mass airflow sensor Air filter restriction indicator

Air filter

Figure 7-3 The air filter is located in the air filter housing within the intake ductwork.

Air Filter Design

An airflow restriction indicator is a meter that shows the amount of air flow past a port. This gives the technician an indicator that the air filter may be not flowing as well as it could because it is dirty.

The intake air temperature (IAT) sensor sends an analog voltage signal to the PCM in relation to air intake temperature.

Air filters are basically assemblies of pleated paper supported by a layer of fine mesh wire screen. The screen gives the paper some strength and also filters out large particles of dirt. A thick plastic-like gasket material normally surrounds the ends of the filter. This gasket adds strength to the filter and serves to seal the filter in its housing. If the filter does not seal well in the housing, dirt and dust can be pulled into the airstream to the cylinders. In most air filters, the air flows from the outside of the element to the inside as it enters the intake system. The shape and size of the air filter element depends on its housing; the filter must be the correct size for the housing or dirt will be drawn into the engine (Figure 7-4). On today’s engines, air filters are either flat (Figure 7-5) or round (Figure 7-6). Air filters must be properly aligned and closed around the filter to ensure good airflow of clean air. Some air cleaners have an airflow restriction indicator mounted in the air cleaner housing (refer to Figure 7-7). If the air filter element is not restricted, a window in the side of the restriction indicator shows a green color (or it may be clear). When the air filter element is restricted, the window in the airflow restriction indicator is orange and the words “Change Air Filter” appears. The air filter must then be replaced. After the air filter is replaced, a reset button on top of the airflow restriction indicator must be pressed to reset the indicator so it displays green in the window. Some air cleaners have a combined MAF sensor and intake air temperature (IAT) sensor attached to the air outlet on the air cleaner housing. A duct is connected from the MAF sensor to the throttle body. The MAF sensor must be attached to the air cleaner so air flows through this sensor in the direction of the arrow on the sensor housing (Figure 7-8).

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Sensor Air duct

Resonator Air cleaner assembly

Figure 7-4 The air cleaner assembly is shaped to fit in the crowded engine compartment.

Figure 7-6 Typical round air filter for a late-model vehicle.

Figure 7-5 Typical flat air cleaner element. Reset button

Window

Change air filter

SERVICE LEVEL Figure 7-7 Airflow restriction indicator.

If the airflow is reversed through the MAF sensor, the powertrain control module (PCM) supplies a rich air-fuel ratio and increased fuel consumption. Other air cleaners contain a separated IAT sensor (Figure 7-9). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Air cleaner case

MAF Sensor airflow direction arrow

Intake air temperature sensor

Figure 7-8 The mass airflow sensor must be installed in the proper direction.

Figure 7-9 The intake air temperature sensor may be mounted in the air cleaner housing.

INTAKE MANIFOLD An intake manifold is a cast iron, aluminum, or plastic component with internal passages that distributes air or an air-fuel mixture from the throttle body or carburetor to the cylinder head intake ports.

The intake manifold distributes the clean air as evenly as possible to each cylinder of the engine. Fuel is injected at the very end of the intake manifold runners near the combustion chamber. Modern intake manifolds for engines with port fuel injection are typically made of die-cast aluminum or plastic (Figure 7-10). These materials are used to reduce engine weight. A plastic manifold transfers less heat to the intake air, and this results in a denser air-fuel mixture. Plastic manifolds are also lower in cost to produce and transfer less vibration, making them quieter. Because intake manifolds for port-injected engines only deliver air to the cylinders, fuel vaporization and condensation are not design considerations. These intake manifolds deliver air to the intake ports, where it is mixed with the fuel delivered by the injectors (Figure 7-11). A primary consideration of these manifolds is the delivery of equal amounts of air to each cylinder.

Figure 7-10 This die-cast aluminum manifold feeds the five-cylinder engine through short runners off of the plenum.

Figure 7-11 In a port fuel injection engine, the intake manifold delivers air to the intake ports.

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Intake manifolds also serve as the mounting point for many intake-related accessories and sensors. Some include a provision for mounting the thermostat and thermostat housing. In addition, connections to the intake manifold can provide a vacuum source for the exhaust gas recirculation (EGR) system, automatic transmission vacuum modulators, power brakes, and/or heater and air-conditioning airflow control doors. Many of these vacuum-operated devices are found only on older vehicles. On modern vehicles they are electronically controlled. When you compare an older engine to a modern one, one of the first things you will notice is the absence of many vacuum-controlled components that would operate from the intake manifold’s vacuum. Other devices located on or connected to the intake manifold include the manifold absolute pressure (MAP) sensor, knock sensor, various temperature sensors, and EGR passages. Most engines cannot produce the amount of power they should at high speeds, because they do not receive enough air. This is the reason why many race cars have hood scoops. With today’s body styles, hood scoops are not desirable, because they increase aerodynamic drag. However, to get high performance out of high-performance engines, more air must be delivered to the cylinders at high engine speeds. There are a number of ways to do this; increasing the air delivered by the intake manifold is one of them.

INTAKE MANIFOLD TUNING Intake manifolds can be designed to improve the volumetric efficiency of the engine. This process is called intake manifold tuning. As the air rushes through the intake manifold into the cylinders, the opening and closing of the intake valves cause the airflow to pulse. If the intake manifold is divided into individual runners for each cylinder, the pulsing effect of the airflow pushes or rams more air into the cylinder. By adjusting or tuning the length of the individual runners, the manufacturer can design an intake manifold to supply the amount of air required by the particular engine. Smaller diameter, longer intake manifold runners ram more air into the cylinders at lower engine rpm. To push more air into the cylinders at higher rpm when air pulsing is faster, the intake manifold runners are designed larger in diameter and shorter. Runners must be curved to avoid sharp bends that create more airflow restriction. Manufacturers have also developed manifolds that deliver more air only at high engine speeds. The design of manifolds is intended to keep air moving quickly. At low rpm, narrower diameter, longer runners keep the smaller volume of air moving quicker. At high rpm, shorter, wider runners offer less restriction and allow the air to keep moving quickly. One such system (Figure 7-12) uses a variable-length intake manifold. At low speeds, the air travels through only part of the manifold on its way to the cylinders. When the engine speed reaches about 3,700 rpm, two butterfly valves open, forcing the air to take a longer route to the intake port. This increases the speed of the airflow, as well as increasing the amount of air available for the cylinders. As a result, more power is available at high speeds without decreasing low-speed torque and fuel economy and without increased exhaust emissions. Another approach is the use of two large intake manifold runners for each cylinder (Figure 7-13). Separating the intake runners from the intake ports is an assembly that has two bores for each cylinder. There is one bore for each runner. Both bores are open when the engine is running at high speeds. However, a butterfly valve in one set of the runners is closed by the PCM when the engine is operating at lower speeds. This action decreases airflow speed and volume at lower engine speeds and allows for greater airflow at high engine speeds. The butterfly valves in the intake manifold runners may be operated by a vacuum actuator, and the PCM operates an electric/vacuum solenoid that turns the vacuum on and off to the actuator. In other intake manifolds, the valves that open and close some of the runners are operated electrically by the PCM, much like a solenoid (Figure 7-14).

A PCM-operated electric solenoid-type valve that opens and closes some of the intake manifold runners may be called an intake manifold tuning valve (IMTV).

The variable-length intake manifold has two runners of different lengths connected to each cylinder head intake port.

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Runner valve open

Runner valve closed

Figure 7-12 A variable-length intake manifold.

Figure 7-13 This manifold provides a short and a long runner for each cylinder. Both are opened at higher engine rpms to improve engine breathing.

Long runner Short runner

Butterfly valves

Vacuum actuator intake manifold runner controls (IMRC)

Figure 7-14 The butterfly valves are controlled by the PCM through a vacuum actuator to open the second set of runners at high rpms.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Intake and Exhaust Systems

Combining a variable intake manifold with a variable valve timing system will increase the power output of a vehicle significantly. In many cases it will also reduce the emissions output and make the engine more efficient. Many vehicles produced today have such a combination of systems.

VACUUM BASICS Vacuum refers to any pressure that is lower than the earth’s atmospheric pressure at any given altitude. Atmospheric pressure appears as zero on most pressure gauges. This does not mean there is no pressure; rather, it means the gauge is designed to read pressures greater than atmospheric pressure. All measurements taken on this type of gauge are given in pounds per square inch and should be referred to as psig (pounds per square inch gauge). Gauges and other measuring devices that include atmospheric pressure in their readings also display their measurements in psi; however, these should be referred to as psia (pounds per square inch absolute). There is a big difference between 12 psia and 12 psig. A reading of 12 psia is less than atmospheric pressure and therefore would represent a vacuum, whereas 12 psig would be approximately 26.7 psia. When referring to the pressure in the intake manifold, we use manifold absolute pressure (MAP) as the measure. MAP is a reading of absolute pressure in the manifold. The MAP reading at idle is typically 7–9 psi. Because vacuum is defined as any pressure less than atmospheric, vacuum is any pressure less than 0 psig or 14.7 psia. Remember that vacuum is simply a difference in the pressures of two areas. Vacuum is not normally measured using negative psi numbers. Vacuum had to originally be measured in a tube filled with mercury, a metal that is in its liquid state at room temperatures. The mercury would then be drawn by the vacuum up a tube, and the amount drawn up was measured in inches. Today, we do not use mercury tubes but rather a calibrated gauge that reads in inches (or millimeters) of mercury (in. Hg or mm Hg). Other units of measurement for vacuum are kilopascals and bars. Normal atmospheric pressure at sea level is about 1 bar or 100 kilopascals. An engine in good condition should develop 16–18 in. Hg vacuum at idle. The amount of low pressure produced by the piston during its intake stroke depends on a number of things. Basically it depends on the cylinder’s ability to form a vacuum and the intake system’s ability to fill the cylinder. When there is high vacuum (16–18 Hg [381 to 559 mm Hg]), we know the cylinder is well sealed and not enough air is entering the cylinder to fill it. At idle, the throttle plate is almost closed and nearly all airflow to the cylinders is stopped. This is why vacuum is high during idle. Because there is a correlation between throttle position and engine load, it can be said that load directly affects engine manifold vacuum. Therefore, vacuum will be high whenever there is no, or low, load on the engine.

VACUUM CONTROLS Engine manifold vacuum is used to operate and control several devices on an engine. Prior to the mid-1960s, vacuum was used only to operate the windshield wipers and a distributor vacuum advance unit. Since then, the use of vacuum has become extensive. Some emission control output devices operate on a vacuum. This vacuum is usually controlled by solenoids that are opened or closed, depending on electrical signals received from the PCM. Engine vacuum is used to control operation of certain accessories, such as air conditioner/ heater systems, power brake boosters, speed-control components, automatic transmission vacuum modulators, and so on. A vacuum solenoid either blocks or flows vacuum to actuate components or control the flow of vacuum. The evaporative emissions control system and the EGR system often use electrically controlled vacuum solenoids (Figure 7-15).

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Figure 7-15 This vacuum solenoid is controlled by the PCM and uses the pull of vacuum to draw fuel vapors into the intake manifold.

TURBOCHARGERS

A turbocharger uses the expansion of exhaust gases to rotate a fan-type wheel, which increases the pressure inside the intake manifold.

A turbine wheel is a vaned wheel in a turbocharger to which exhaust pressure is supplied to provide shaft rotation.

Another method of improving volumetric efficiency and engine performance is to compress the intake air before it enters the combustion chamber. This can be accomplished through the use of a turbocharger or a supercharger. While at idle the engine still develops the same amount of vacuum; under boost the supercharger or turbocharger delivers roughly 8–15 psi of pressure above atmospheric pressure. When the throttle opens, the greater pressure difference increases airflow into the cylinders. This increases the density of the air charge in the cylinder producing more power. A turbocharger or supercharger changes the effective compression ratio of an engine, simply by packing in air at a pressure that is greater than atmospheric; for example, an engine that has a compression ratio of 8:1 and receives 10 pounds (69 kPa) of boost will have an effective compression ratio of 10.5:1. A turbocharger is a blower or special fan assembly that uses the expansion of hot exhaust gases to turn a turbine and compress incoming air. In a typical car engine, a turbocharger may increase the horsepower approximately 20 percent. A typical turbocharger consists of the following components: ■ Turbine wheel ■ Shaft ■ Compressor wheel ■ Wastegate valve ■ Actuator ■ Center housing and rotating assembly (CHRA)

Basic Operation The turbine wheel and the compressor wheel are mounted on a common shaft. Both wheels have fins or blades, and each wheel is encased in its own spiral-shaped housing.

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Compressed air Exhaust gas

Turbine wheel

Inlet air

Compressor wheel

Exhaust

Figure 7-16 Exhaust gases spin the turbine wheel. The compressor wheel is connected to the turbine through a shaft and spins at the same rate to pressurize the intake charge.

The shape of the housing works to control and direct the flow of the gases. The shaft is supported on bearings in the turbocharger housing. The expelled exhaust gases from the cylinders are directed through a nozzle against the blades of the turbine wheel. When engine load is high enough, there is enough exhaust gas flow to cause the turbine wheel and shaft to rotate at a high speed. This action creates a vortex flow. Since the compressor wheel is positioned on the opposite end of the shaft, the compressor wheel must rotate with the turbine wheel (Figure 7-16). The compressor wheel is mounted in the air intake system. As the compressor wheel rotates, air is forced into the center of the wheel, where it is caught by the spinning blades and thrown outward by centrifugal force. The air leaves the turbocharger housing and enters into the intake manifold. Since most turbocharged engines are port injected, the fuel is injected into the intake ports. The rotation of the compressor wheel compresses the air and fuel in the intake manifold, creating a denser air-fuel mixture. This increased intake manifold pressure forces more air-fuel mixture into the cylinders to provide increased engine power. The turbocharger must reach a certain rpm before it begins to pressurize the intake manifold. Some turbochargers begin to pressurize the intake manifold at 1,250 engine rpm and reach full boost pressure in the intake manifold at 2,250 rpm. In a normally aspirated engine, air is drawn into the cylinders by the difference in pressure between the atmosphere and engine vacuum. A turbocharger pressurizes the intake charge to a point above normal atmospheric pressure. Turbo boost is the positive pressure increase created by the turbocharger.

A compressor wheel is a vaned wheel mounted on the turbocharger shaft that forces air into the intake manifold. Turbo boost is a term used to describe the amount of positive pressure increase of the turbocharger; for example, 10 psi (69 kPa) of boost means the air is being induced into the engine at 24.7 psi (170 kPa). Normal atmospheric pressure is 14.7 psi (101 kPa); add the 10 psi (69 kPa) to get 24.7 psi (170 kPa).

A BIT OF HISTORY Turbochargers have been common in heavy-duty applications for many years, but they were not widely used in the automotive industry until the 1980s. Turbochargers had two traditional problems that prevented their wide acceptance in automotive applications. Older turbochargers had a lag, or hesitation, on low-speed acceleration, and there was the problem of bearing cooling. Engineers greatly reduced the low-speed lag by designing lighter turbine and compressor wheels with improved blade design. Water cooling combined with oil cooling provided improved bearing life. These changes made the turbocharger more suitable for automotive applications.

Turbocharger wheels rotate at very high speeds, in excess of 100,000 rpm. Engineers design and balance the turbocharger to run in excess of 150,000 rpm, about 25 times the maximum rpm of most engines. Due to this high-speed operation, turbocharger wheel balance and bearing lubrication are very important. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Boost Pressure Control. If the turbocharger boost pressure is not limited, excessive intake manifold and combustion pressure can destroy engine components. Also, if the amount of boost is too high, detonation knock can occur and decrease engine output. To control the amount of boost developed in the turbocharger, most turbochargers have a wastegate diaphragm mounted on the turbocharger. A linkage is connected from this diaphragm to a wastegate valve in the turbine wheel housing (Figure 7-17). Under low to partial load conditions, the diaphragm spring holds the wastegate valve closed. This routes all of the exhaust gases through the turbine housing. Boost pressure from the intake manifold is also supplied to the wastegate diaphragm. Under full load, when the boost pressure in the intake manifold reaches the maximum safe limit, the boost pressure pushes the wastegate diaphragm and opens the wastegate valve. This action allows some exhaust to bypass the turbine wheel, which limits turbocharger shaft rpm and boost pressure (Figure 7-18). On some engines, the boost pressure supplied to the wastegate diaphragm is controlled by a computer-operated solenoid. In many systems, the PCM pulses the wastegate solenoid on and off to control boost pressure. Some computers are programed to momentarily allow a higher boost pressure on sudden acceleration to improve engine performance.

A wastegate limits the maximum amount of turbocharger boost by directing the exhaust gases away from the turbine wheel. The wastegate valve is also referred to as a bypass valve.

Wastegate diaphragm

Figure 7-17 The wastegate diaphragm is operated by a PCM-controlled solenoid to protect the engine from dangerous overboosting. Manifold pressure Boost pressure

Exhaust gas

Wastegate (open) Intake manifold

Compressor Turbine

Exhaust

Figure 7-18 As boost pressure increases toward the safe limit, the wastegate opens to divert exhaust gases away from the turbine wheel. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Turbo Lag Turbo lag occurs when the turbocharger compressor and turbine wheels are not spinning fast enough to create boost. It takes time to get the exhaust gases to bring the turbocharger wheels up to operating speed. The size and weight of the turbine and compression wheels, along with housing design, are factors that affect the amount of turbo lag. Smaller, lighter turbochargers result in less lag time but lower boost pressures. Some engines use two sequential turbochargers: a very small, lightweight one to help acceleration at low rpms and a bigger volume one to create plenty of boost to maximize power at higher rpms. Low-pressure turbochargers may provide boost of only 4–8 psi, but they reduce the lag time until the 8–15 psi from the full-size turbo kicks in. Also used on some diesel engines, variable nozzle turbine turbocharger systems have been developed to reduce the lag period (Figure 7-19).

Turbo lag is a short delay period before the turbocharger develops sufficient boost pressures.

Turbocharger Cooling Exhaust flow past the turbine wheel creates very high turbocharger temperature, especially under high engine load conditions. Many turbochargers have coolant lines connected from the turbocharger housing to the cooling system (Figure 7-20). Coolant circulation through the turbocharger housing helps cool the bearings and shaft. Full oil pressure is supplied from the main oil gallery to the turbocharger bearings and shaft to lubricate and cool the bearings. This oil is drained from the turbocharger housing back into the crankcase. Seals on the turbocharger shaft prevent oil leaks into the compressor or turbine wheel housings. Worn turbocharger seals allow oil into the compressor or turbine wheel housings, resulting in blue smoke in the exhaust and oil consumption. Some heat is also dissipated from the turbocharger to the surrounding air. Some turbochargers do not have coolant lines connected to the turbocharger housing. These units depend on oil and air cooling. On these units, if the engine is shut off immediately after heavy-load or high-speed operation, the oil may burn to some extent in the turbocharger bearings. When this action occurs, hard carbon particles, which destroy the turbocharger bearings, are created. The coolant circulation through the turbocharger housing lowers the bearing temperature to help prevent this problem. When turbochargers that depend on oil and air cooling have been operating at heavy load or high speed, idle the engine for at least one minute before shutting it off. This action will help prevent turbocharger bearing failure.

Intercoolers A disadvantage of the turbocharger (and supercharger) is that it heats the incoming air. The hotter the air, the less dense it is. As the air gets hotter, fewer air molecules can enter the cylinder on each intake stroke. Also, hotter intake air leads to detonation problems. Bearings

Coolant delivery tube

Figure 7-19 Variable nozzle turbine type turbocharger.

Water passages

Banjo-style water fitting (2)

Figure 7-20 A water-cooled turbocharger uses coolant to control the temperature of the bearings and the shaft.

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Figure 7-21 The intercooler cools the pressurized air to create a denser intake charge. The intercooler cools the intake air temperature to increase the density of the air entering the cylinders. It is also referred to as a charge air cooler.

To combat these effects, many turbocharger systems use an intercooler (Figure 7-21). The intercooler is like a radiator in that it removes heat from the turbocharger system by dissipating it to the atmosphere. The intercooler can be either air cooled or water cooled (Figure 7-22). Cooling the air makes it denser, increasing the amount of oxygen content with each intake stroke. The intercooler cools the air that leaves the turbocharger at about 1008F (388C) before it enters the cylinders. For every 108F (5.58C) that the air is cooled, a power gain of about 1 percent is obtained. If the intercooler is capable of cooling the air by 1008F (388C), then a 10 percent power increase is obtained.

Scheduled Maintenance Oil coking occurs after the engine is shut down and the turbocharger is still spinning. The oil is no longer circulating, and what remains inside the turbo can literally bake into a white, hard, caked restriction in the lines. Allowing the engine to idle for a minute before shutting the engine off allows the turbo compressor to wind down and prevents this.

Four main things will reduce the life of a turbocharger: lack of oil, oil coking, contaminants in the oil, and ingestion of foreign material through the air intake. To prevent premature turbocharger failure, engine oil and filters should be changed at the vehicle manufacturer’s recommended intervals. The engine oil level must be maintained at the specified level on the dipstick. The air cleaner element and the air intake system must be maintained in satisfactory condition. Dirt entering the engine through an air cleaner will damage the compressor wheel blades. When coolant lines are connected to the turbocharger housing, the cooling system must be maintained according to the vehicle manufacturer’s maintenance schedule to provide normal turbocharger life. Turbocharged engines have a lower compression ratio than a normally aspirated engine, and many parts are strengthened in a turbocharged engine because of the higher cylinder pressure. Therefore, many components in a turbocharged engine are not interchangeable with the parts in a normally aspirated engine.

AUTHOR’S NOTE During my experience in the automotive service industry, I encountered a significant number of turbocharged engines with low boost pressure. This low boost pressure was often caused by low engine compression. Because low engine compression reduces the amount of air taken into the engine, this problem also reduces turbocharger speed and boost pressure. Therefore, when diagnosing low boost pressure, always verify the engine condition before servicing or replacing the turbocharger. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Intercooler

Intake manifold Exhaust inlet

Turbocharger inlet Turbocharger exhaust Subradiator

Exhaust manifold Electric water pump

Air cooled intercooler

Outside air

Water cooled intercooler

Exhaust gas

Throttle plate

Intake manifold

Exhaust gas

Intake manifold Exhaust

A

Exhaust

B

Figure 7-22 Intercoolers can be air cooled (A) or water cooled (B).

SUPERCHARGERS After falling into disuse for a number of years (except for racing applications), the supercharger started to reappear on automotive engines as original equipment manufacturer (OEM) in 1989 (Figure 7-23). The supercharger is belt driven from the crankshaft by a ribbed belt (Figure 7-24). A shaft is connected from the crankshaft pulley to one of the drive gears in the front supercharger housing, and the driven gear is meshed with the drive gear. The rotors inside the supercharger are attached to the two drive gears. The drive gear design prevents the rotors from touching; however, there is a very small clearance between the drive and driven gears. In some superchargers, the rotor shafts are supported by roller bearings on the front and needle bearings on the back. During the manufacturing process, the needle bearings are permanently lubricated. The ball bearings are lubricated by a synthetic-based, high-speed gear oil. A plug is provided for periodic checks of the front bearing lubricant. Front bearing seals prevent lubricant loss into the supercharger housing. In a typical car engine, a supercharger increases horsepower approximately 20 percent compared to a normally aspirated engine with the same CID; for example, the General Motors normally aspirated 1997 3800 V-6 engine is rated at 200 HP. The supercharged version of this engine is rated at 240 HP. The supercharger will operate around 10,000 to 15,000 rpm. Unlike the turbocharger, the amount of boost the supercharger produces is a

The supercharger is a belt-driven air pump used to increase the compression pressures in the cylinders.

The supercharger may be called a blower.

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Figure 7-23 A factory-installed supercharger.

Supercharger drive pulley

Spring tensioner

Idler pulley assembly

Belt cross section

Crankshaft pulley Spring tensioner

Figure 7-24 The supercharger is driven by a belt off of the crankshaft.

function of engine rpm (not load). The advantage of the supercharger is that it will produce more torque at lower engine speeds than a turbocharger. Also, there is no lag time associated with a supercharger. The disadvantage of the supercharger is that it consumes horsepower as it is driven.

Supercharger Operation The Roots-type supercharger is a positive displacement supercharger that uses a pair of lobed vanes to pump and compress the air.

While there have been a number of supercharger designs on the market over the years, the most popular is the Roots-type supercharger. The pair of three-lobed rotor vanes (Figure 7-25) in the Roots supercharger is driven by the crankshaft. The lobes force air into the intake manifold. The helical design evens out the pressure pulses in the blower and reduces noise. It was found that a 60-degree helical twist works best for equalizing the inlet and outlet volumes. Another benefit of the helical rotor design is it reduces carryback volumes—air that is carried back to the inlet side of the supercharger because of the unavoidable spaces between the meshing rotors—which represents a loss of efficiency. Many aftermarket superchargers are a centrifugal type.

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Three-lobed rotor vane (2)

Figure 7-25 Common design of the rotor.

To handle the higher operating temperatures imposed by supercharging, an engine oil cooler is usually built into the engine lubrication system. This water-to-oil cooler is generally mounted between the engine front cover and oil filter. Intake air enters the inlet plenum at the back of the supercharger, and the rotating blades pick up the air and force it out the top of the supercharger. The blades rotate in opposite directions, acting as a pump as they rotate. This pumping action pulls air through the supercharger inlet and forces the air from the outlet. There is a very small clearance between the meshed rotor lobes and between the rotor lobes and the housing (Figure 7-26). Air flows through the supercharger system components in the following order: 1. Air flows through the air cleaner and MAF sensor into the throttle body. 2. Airflow enters the supercharger intake plenum. 3. From the intake plenum the air flows into the rear of the supercharger housing (Figure 7-27). 4. The compressed air flows from the supercharger to the intercooler inlet. 5. Air leaves the intercooler and flows into the intercooler outlet tube. 6. Air flows from the intercooler outlet tube into the intake manifold adapter. 7. Compressed, cooled air flows through the intake manifold into the engine cylinders. 8. If the engine is operating at idle or very low speeds, the supercharger is not required. Under this condition, airflow is bypassed from the intake manifold adapter through a butterfly valve to the supercharger inlet plenum (Figure 7-28). Intercooler

Boost pressure pushed out into intake manifold

Intake manifold adapter

Supercharger Throttle body

PSI developing

Figure 7-26 As the rotors mesh, they pump air out under pressure.

Figure 7-27 Airflow through a supercharger.

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Intake manifold adapter

Supercharger Throttle body

Figure 7-28 The bypass actuator can divert airflow from the intake manifold back into the supercharger plenum to reduce boost.

In one example, the bypass butterfly valve (Figure 7-29) is operated by an air bypass actuator diaphragm as follows: 1. When manifold vacuum is 7 in. Hg (23.6 kPa) or higher, the bypass butterfly valve is completely open and a high percentage of the supercharger air is bypassed to the supercharger inlet. Elbow assembly

Bypass hose

Front of Engine

Bypass valve

Supercharger and plenum assembly

Figure 7-29 Supercharger bypass hose and intake elbow. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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2. If the manifold vacuum is 3 to 7 in. Hg (10 to 23.6 kPa), the bypass butterfly valve is partially open and some supercharger air is bypassed to the supercharger inlet, while the remaining airflow is forced into the engine cylinders. 3. When the vacuum is less than 3 in. Hg (10 kPa), the bypass butterfly valve is closed and all the supercharger airflow is forced into the engine cylinders. On some superchargers, the pulley size causes the rotors to turn at 2.6 times the engine speed. Since supercharger speed is limited by engine speed, a supercharger wastegate is not required. Belt-driven superchargers provide instant low-speed action compared to exhaust-driven turbochargers, which may have a low-speed lag because of the brief time interval required to accelerate the turbocharger shaft. Compared to a turbocharger, a supercharger turns at much lower speeds. Friction between the air and the rotors heats the air as it flows through the supercharger. The intercooler dissipates heat from the air in the supercharger system to the atmosphere, creating a denser air charge. When the supercharger and the intercooler supply cooled, compressed air to the cylinders, engine power and performance are improved. The compression ratio in the supercharged 3.8-liter engine is 8.2:1, compared to a normally aspirated 3.8-liter engine, which has a 9.0:1 compression ratio. The following components are reinforced in the supercharged engine because of the higher cylinder pressure: ■ Engine block ■ Main bearings ■ Crankshaft bearing caps ■ Crankshaft ■ Steel crankshaft sprocket ■ Timing chain ■ Cylinder head ■ Head bolts ■ Rocker arms Superchargers can be enhanced with electrically operated clutches and bypass valves. These allow the same computer that controls fuel and ignition to kick the boost on and off precisely as needed. This results in far greater efficiency than a full-time supercharger.

EXHAUST SYSTEM COMPONENTS The various components of the typical exhaust system include the following: ■ Exhaust manifold ■ Exhaust pipe and seal ■ Catalytic converter ■ Muffler ■ Resonator ■ Tailpipe ■ Heat shields ■ Clamps, brackets, and hangers ■ Exhaust gas oxygen sensors All the parts of the system are designed to conform to the available space of the vehicle’s undercarriage and yet be a safe distance above the road.

Exhaust Manifold The exhaust manifold (Figure 7-30) collects the burnt gases as they are expelled from the cylinders and directs them to the exhaust pipe. Exhaust manifolds for most vehicles are made of cast or nodular iron. Many newer vehicles have stamped, heavy-gauge sheet metal or stainless steel units.

The exhaust manifold is an exhaust collector that is mounted onto the cylinder head.

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Figure 7-30 An exhaust manifold for a four-cylinder engine.

In-line engines have one exhaust manifold. V-type engines have an exhaust manifold on each side of the engine. An exhaust manifold will have three, four, or six passages, depending on the type of engine. These passages blend into a single passage at the other end, which connects to an exhaust pipe. From that point, the flow of exhaust gases continues to the catalytic converter, muffler, and tailpipe, and then exits at the rear of the car. V-type engines may be equipped with a dual exhaust system that consists of two almost identical, but individual, systems in the same vehicle. Exhaust systems are designed for particular engine–chassis combinations. Exhaust system length, pipe size, and silencer size are used to tune the flow of gases within the exhaust system. Proper tuning of the exhaust manifold tubes can actually create a partial vacuum that helps draw exhaust gases out of the cylinder, improving volumetric efficiency. Separate, tuned exhaust headers (Figure 7-31) can also improve efficiency by preventing the exhaust flow of one cylinder from interfering with the exhaust flow of another cylinder. Cylinders next to one another may release exhaust gas at about the same time.

Figure 7-31 Engine efficiency can be improved with tuned exhaust headers. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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When this happens, the pressure of the exhaust gas from one cylinder can interfere with the flow from the other cylinder. With separate headers, the cylinders are isolated from one another, interference is eliminated, and the engine breathes better. The problem of interference is especially common with V-8 engines. However, exhaust headers tend to improve the performance of all engines. Exhaust manifolds may also be the attaching point for the air injection reaction (AIR) pipe (Figure 7-32). This pipe introduces cool air from the AIR system into the exhaust stream. The added air in the exhaust stream during engine warm-up helps burn excess fuel in the exhaust and heat up the catalytic converter faster. Some exhaust manifolds have provisions for the exhaust gas recirculation (EGR) pipe. This pipe takes a sample of the exhaust gases and delivers it to the EGR valve. Also, some exhaust manifolds have a tapped bore that retains the oxygen sensor (Figure 7-33).

Exhaust Pipe and Seal The exhaust pipe is metal pipe, made of aluminized steel, stainless steel, or zinc-plated heavy gauge steel, that runs under the vehicle between the exhaust manifold and the catalytic converter (Figure 7-34). A catalytic converter reduces tailpipe emissions of carbon monoxide, unburned hydrocarbons, and nitrogen oxides.

Catalytic Converters A catalytic converter (Figure 7-35) is part of the exhaust system and a very important part of the emission control system. Because it is part of both systems, it has a role in both. As an emission control device, it is responsible for converting undesirable exhaust gases Exhaust manifold

Oxygen sensor

Catalytic converter

Oxygen sensor Air injection reaction pipe

Figure 7-32 AIR pipe mounting on an exhaust manifold.

Figure 7-33 One oxygen sensor sits in this exhaust manifold. The catalytic converter mounts onto the exhaust manifold, and another oxygen sensor fits into the exhaust pipe.

Outer shell

Exhaust pipe

Monolith catalyst

Oxygen sensor

Insulation

Exhaust gasket Inner shell

Figure 7-34 The front exhaust pipe for a V-6 engine.

Figure 7-35 Monolithic-type catalytic converter.

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into harmless gases. As part of the exhaust system, it helps reduce the noise level of the exhaust. A catalytic converter contains a ceramic element coated with a catalyst. A catalyst is a substance that causes a chemical reaction in other elements without actually becoming part of the chemical change and without being used up or consumed in the process. Catalytic converters may be pellet type or monolithic type. A pellet-type converter contains a bed made from hundreds of small beads and is mostly used on older vehicles. Exhaust gases pass over this bed. In a monolithic-type converter, the exhaust gases pass through a honeycomb ceramic block. The converter beads or ceramic block are coated with a thin coating of cerium, platinum, palladium, rhodium, or any combination of these and are held in a stainless-steel container. Modern vehicles are equipped with three-way catalytic converters, which means the converter reduces the three major exhaust emissions, hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NO x ). The converter oxidizes HC and CO into water vapor and carbon dioxide (CO 2) and reduces NO x to oxygen and nitrogen. Many vehicles are equipped with a mini-catalytic converter that either is built into the exhaust manifold or is located next to it (Figure 7-36). These converters are used to clean the exhaust during engine warm-up and are commonly called warm-up converters. Some older catalytic converters have an air hose connected from the AIR system to the oxidizing catalyst. This air helps the converter work by making extra oxygen available. The air from the AIR system is not always forced into the converter; rather, it is controlled by the vehicle’s PCM. Fresh air added to the exhaust at the wrong time could overheat the converter and produce NO x , something the converter is trying to destroy. OBD II regulations call for a way to inform the driver that the vehicle’s converter has a problem and may be ineffective. The PCM monitors the activity of the converter by comparing the signals of an HO 2S located at the front of the converter with the signals from an HO 2S located at the rear (Figure 7-37). If the sensor outputs are the same, the converter is not working properly and the malfunction indicator lamp (MIL) on the dash will light.

Converter Problems The converter is normally a trouble-free emission control device, but three things can damage it. One is leaded gasoline. Lead coats the catalyst and renders it useless. The difficulty of obtaining leaded gasoline has reduced this problem. Another is overheating.

Figure 7-36 A warm-up converter may be used before the primary converter. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Warm-up catalytic converter Main catalytic converter

Muffler

Front pipe

O2 sensor O2 sensor

Figure 7-37 Exhaust system for an OBD II vehicle.

If raw fuel enters the exhaust because of a fouled spark plug or other problem, the temperature of the converter quickly increases. The heat can melt the ceramic honeycomb or pellets inside, causing a major restriction to the flow of exhaust. A plugged converter or any exhaust restriction can cause damage to the exhaust valves due to excess heat, loss of power at high speeds, or stalling after starting (if totally blocked). The last is damage or poisoning due to silicone contamination from coolant or sealant.

MUFFLERS The muffler is a cylindrical or oval-shaped component, generally about 2 feet (0.6 meters) long, mounted in the exhaust system about midway or toward the rear of the car. Inside the muffler is a series of baffles, chambers, tubes, and holes to break up, cancel out, or silence the pressure pulsations that occur each time an exhaust valve opens. Two types of mufflers are commonly used on passenger vehicles (Figure 7-38). Reverse-flow mufflers change the direction of the exhaust gas flow through the inside of the unit. This is the most common type of automotive muffler. Straight-through mufflers permit exhaust gases to pass through a single tube. The tube has perforations that tend to break up pressure pulsations. They are not as quiet as the reverse-flow type. There have been several important changes in recent years in the design of mufflers. Most of these changes have been centered at reducing weight and emissions, improving fuel economy, and simplifying assembly. These changes include the following:

The muffler is a device mounted in the exhaust system behind the catalytic converter that reduces engine noise.

1. New materials. More and more mufflers are being made of aluminized and stainless steel. Using these materials reduces the weight of the units as well as extends their lives. 2. Double-wall design. Retarded engine ignition timing that is used on many small cars tends to make the exhaust pulses sharper. Many cars use a double-wall exhaust pipe to better contain the sound and reduce pipe ring.

A

B

Figure 7-38 (A) Reverse-flow muffler, (B) Straightthrough muffler. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Back pressure reduces an engine’s volumetric efficiency.

3. Rear-mounted muffler. More and more often, the only space left under the car for the muffler is at the very rear. This means the muffler runs cooler than before and is more easily damaged by condensation in the exhaust system. This moisture, combined with nitrogen and sulfur oxides in the exhaust gas, forms acids that rot the muffler from the inside out. Many mufflers are being produced with drain holes drilled into them. 4. Back pressure. Even a well-designed muffler will produce some back pressure in the system. Back pressure reduces an engine’s volumetric efficiency, or ability to breathe. Excessive back pressure caused by defects in a muffler or other exhaust system part can slow or stop the engine. However, a small amount of back pressure can be used intentionally to allow a slower passage of exhaust gases through the catalytic converter. This slower passage results in more complete conversion to less harmful gases. Also, no back pressure may allow intake gases to enter the exhaust.

Resonator A resonator is a device mounted on the tailpipe to reduce exhaust noise further.

On some older vehicles, there is an additional muffler, known as a resonator or silencer. This unit is designed to further reduce or change the sound level of the exhaust. It is located toward the end of the system and generally looks like a smaller, rounder version of a muffler.

Tailpipe The tailpipe conducts exhaust gases from the muffler to the rear of the vehicle.

The tailpipe is the last pipe in the exhaust system. It releases the exhaust fumes into the atmosphere beyond the back end of the car.

Heat Shields Heat shields are used to protect other parts from the heat of the exhaust system and the catalytic converter (Figure 7-39). They are usually made of pressed or perforated sheet metal. Heat shields trap the heat in the exhaust system, which has a direct effect on maintaining exhaust gas velocity.

A BIT OF HISTORY In the 1930s Charles Nelson Pogue developed the Pogue carburetor. This carburetor used exhaust heat to vaporize the fuel before it was mixed with the air entering the engine. Charles Pogue was issued several patents on this carburetor and claimed greatly increased fuel mileage. Mr. Pogue never did sell his invention to any of the car manufacturers, but rumors were repeated for years about the fantastic fuel economy supplied by this carburetor.

Clamps, Brackets, and Hangers Clamps, brackets, and hangers are used to properly join and support the various parts of the exhaust system. These parts also help isolate exhaust noise by preventing its transfer through the frame (Figure 7-40) or body to the passenger compartment. Clamps help secure exhaust system parts to one another. The pipes are formed in such a way that one slips inside the other. This design makes a close fit. A U-type clamp usually holds this connection tight (Figure 7-41). Another important job of clamps and brackets is to hold pipes to the bottom of the vehicle. Clamps and brackets must be designed to allow the exhaust system to vibrate without transferring the vibrations through the car. Many different types of flexible hangers are available. Each is designed for a particular application. Some exhaust systems are supported by doughnut-shaped rubber rings Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Upstream HO2S sensor (used for fuel control) Heat insulator Rubber hangers

Gasket

Catalytic converter

Downstream HO2S sensor (used for catalyst testing)

U-bolt

Heat insulators

Muffler

Clamp

Resonator

Figure 7-39 Typical locations of heat shields in an exhaust system.

Figure 7-40 Rubber hangers are used to keep the exhaust system in place without allowing it to contact the frame.

Nuts

Figure 7-41 A U-clamp is often used to secure two pipes that slip together.

between hooks on the exhaust component and on the frame or car body. Others are supported at the exhaust pipe and tailpipe connections by a combination of metal and reinforced fabric hanger. Both the doughnuts and the reinforced fabric allow the exhaust system to vibrate or move without breakage that could be caused by direct physical connection to the vehicle’s frame. Some exhaust systems are a single unit in which the pieces are welded together by the factory. By welding instead of clamping the assembly together, car makers save the weight of overlapping joints as well as that of clamps.

AUTHOR’S NOTE During my experience in the automotive service industry, I encountered several cases where restricted exhaust or intake systems were misdiagnosed and confused with ignition system or fuel system defects. Defective fuel system or ignition system components may cause a loss of engine power and reduced maximum speed, but these symptoms are accompanied by cylinder misfiring, engine surging, or both. When the exhaust or intake system is restricted, the maximum speed is reduced, but the engine does not misfire or surge.

SUMMARY ■

■

The air induction system allows a controlled amount of clean, filtered air to enter the engine. Cool air is drawn in through a fresh air tube. It passes through an air cleaner before entering the throttle body. The air intake ductwork conducts airflow from the remote air cleaner to the throttle body mounted on the intake manifold.

■

■

The air cleaner/filter removes dirt particles from the air flowing into the intake manifold, to prevent these particles from causing engine damage. The intake manifold distributes the air or air-fuel mixture as evenly as possible to each cylinder. Intake manifolds are made of cast iron, plastic, or die-cast aluminum.

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■

■

■

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The vacuum in the intake manifold operates many systems such as emission controls, brake boosters, heater/air conditioner, cruise controls, and more. A diagram of emission system vacuum hose routing is located on the underhood decal. Loss of vacuum can create many drivability problems. Turbochargers and superchargers create forced induction systems that improve the volumetric efficiency and power of the engine. Turbochargers use the heat energy in exhaust gases to spin the turbine and pressurize intake air on the compressor side. A turbocharger wastegate regulates boost pressure based on engine load to prevent engine-damaging overboost conditions. A belt-driven supercharger supplies air to the intake manifold under pressure to increase engine power.

■

A vehicle’s exhaust system carries away gases from the passenger compartment, cleans the exhaust emissions, and muffles the sound of the engine. Its components include the exhaust manifold, exhaust pipe, catalytic converter, muffler, resonator, tailpipe, heat shields, clamps, brackets, and hangers.

■

The exhaust manifold is a bank of pipes that collects the burned gases as they are expelled from the cylinders and directs them to the exhaust pipe.

■

The catalytic converter reduces HC, CO, and NO x emissions.

■

The muffler consists of a series of baffles, chambers, tubes, and holes to break up, cancel out, and silence pressure pulsations.

REVIEW QUESTIONS Short-Answer Essays 1. Explain the operation of an airflow restriction indicator. 2. Explain the purposes of the intake manifold. 3. Explain the advantages of plastic intake manifolds. 4. Explain the operation of an intake manifold with dual runners at low and high engine speeds. 5. Explain how a turbocharger or supercharger creates more engine power. 6. Describe basic turbocharger operation. 7. What is the purpose of the intercooler? 8. Describe the advantages of tuned exhaust manifolds compared to conventional exhaust manifolds. 9. Explain two catalytic converter operating problems.

2. If the air filter is restricted, the airflow restriction indicator window appears _______________ in color. 3. When an intake manifold has dual runners, both runners are open at _______________ engine speeds. 4. The exhaust flows over the _______________ wheel in a turbocharger. 5. Turbocharged or supercharged engines have _______________ compression ratios compared to naturally aspirated engines. 6. The air flows through the intercooler _______________ it flows through the supercharger. 7. In place of cast- or nodular-iron exhaust manifolds, newer vehicles have manifolds manufactured from stamped, heavy-gauge sheet metal or _______________ _______________.

10. When referring to a turbocharger system, describe what oil coking is, how it is caused, and how to prevent it.

8. A tuned exhaust manifold prevents exhaust flow from one cylinder from interfering with the _______________ _______________ from another cylinder.

Fill-in-the-Blanks

9. A catalytic converter may be overheated by a(n) _______________ air-fuel ratio.

1. Without proper intake air filtration, contaminants and abrasives in the air will cause severe _______________ damage.

10. The exhaust pipe between the engine and the catalytic converter may be a _______________ _______________ design in order to be quieter.

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Multiple Choice 1. The intake manifold is typically made of. A. plastic. C. cast iron. B. stainless steel. D. fiber composites. 2. An engine should develop _______________ in. Hg vacuum at idle. A. 5 C. 18 B. 8 D. 25 3. A variable-length intake manifold is designed to increase. A. compression. C. intake turbulence. B. airflow at idle. D. airflow at high rpm. 4. The catalytic converter reduces _______________ emissions. A. HC, CO 2, O 2 C. CO, CO 2, NO x B. HC, CO, NO x D. N, HC, O 2 5. Technician A says that a turbocharger may spin at speeds of 100,000 rpm. Technician B says that oil coking is a common cause of turbocharger failure. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 6. On a turbocharged engine, when the opens, boost pressure is reduced. A. Compressor bypass B. Turbine dump valve C. Wastegate D. Intercooler router

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7. A supercharger typically uses _______________ to pressurize the intake charge. A. two rotors B. four rotors C. a compressor pump D. three helix gears 8. A mini-converter is used. A. on small engines where a normal converter will not fit properly. B. on engines that used leaded fuels. C. in conjunction with EGR systems to supply clean exhaust for the cylinders. D. to reduce emissions during engine warm-up. 9. A restricted exhaust system can cause. A. stalling. B. backfiring. C. loss of power. D. acceleration stumbles. 10. All of these statements about an intake manifold dual runner system are true except: A. Both runners to each cylinder are open at 1,400 engine rpm. B. The butterfly valves in one set of runners may be operated by a vacuum actuator. C. The butterfly valves may be operated electrically by the PCM. D. One runner to each cylinder is open at 900 engine rpm.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 8

ENGINE CONFIGURATIONS, MOUNTS, AND REMANUFACTURED ENGINES

Upon completion of this chapter, you should understand and be able to describe: ■ ■ ■ ■

A remanufactured engine is one that has been professionally rebuilt by a manufacturer or engine supplier.

A crate engine is a new or remanufactured engine that is built with fresh components, such as bearings, rings, and lifters. You can purchase crate engines with or without cylinder heads.

When an engine is mounted perpendicular to the drivetrain, it is said to be a transversemounted engine.

The differential allows the wheels to turn at different speeds as the vehicle turns corners. It is internal to a transaxle and external to a transmission.

The engine cradle, which is also called the suspension cradle, is the front frame member(s) in a unibody design. The engine is mounted to this frame, as is the suspension.

168

The different engine configurations. The methods of mounting the engine. The function of different engine mounts. The common attaching points for the engine.

■ ■

The common accessories found on the engine assembly. The benefits and limitations of a remanufactured engine.

Terms To Know Crate engine Differential Engine cradle

Engine mount Longitudinally mounted Mid-mounted engine

Remanufactured engine Transverse-mounted engine

INTRODUCTION When performing major engine mechanical repairs, you will be confronted with different engine configurations. The engine may be mounted transversely or longitudinally, or it may be a mid-engine, which is mounted in the rear. You will need to understand the operation of motor mounts as part of your assurance that the engine will perform smoothly. When overhauling or replacing an engine, you will have to remove many engine accessories and brackets; this requires some familiarity with these components. In many cases, you, your shop management, or your customer may choose to install a remanufactured engine. You will need to understand the benefits and limitations of choosing a “reman” or crate engine versus you overhauling the engine in-house.

ENGINE CONFIGURATIONS The most common configuration for a front-wheel-drive vehicle is to have a transversemounted engine (Figure 8-1). The engine is mounted sideways in the engine compartment so that the front of the engine is mounted toward one side of the vehicle. This is a popular design, in part because it can reduce the size of the engine compartment. The transaxle is attached to the side of the engine and faces the other side of the vehicle. The transaxle contains the differential assembly, located in the rear of the vehicle on rearwheel-drive vehicles. The compact size of the transaxle lowers overall vehicle weight. This is always a goal of vehicle manufacturers as they try to improve fuel economy. A transverse engine is often removed from the bottom of the engine compartment with the transaxle attached. This often requires parts of the engine cradle (suspension cradle) to be removed (Figure 8-2). The engine and the suspension components are attached to the engine cradle, so disassembly of parts of the suspension may be required to remove the engine.

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Figure 8-1 This transverse-mounted engine has many accessories and attachments that would have to be removed during an engine overhaul or an engine swap. Cradle toward the rear of the vehicle

Cradle mount

Engine cradle under the front of the vehicle

Figure 8-2 This engine cradle comes out as one piece to remove the engine through the bottom. The suspension will have to be disconnected.

Many rear-wheel-drive and four-wheel-drive vehicles install their engines longitudinally (Figure 8-3). A few front-wheel-drive vehicles also mount their engines in this fashion, though it is not common. With a longitudinally mounted engine, the front of the engine faces the front of the vehicle, and the transmission mounts on the back of the engine. The engine and transmission are bolted together and mounted to the frame through a rear engine mount (Figure 8-4). A longitudinal engine may be removed from the top through the hood opening or through the bottom of the engine compartment.

A longitudinally mounted engine is placed in the vehicle lengthwise, usually front to rear.

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Figure 8-3 A longitudinal engine mounted in an all-wheel-drive SUV.

Transmission

Rear engine mount

Engine mount bracket Cross member

Figure 8-4 The engine and transmission use a rear engine mount to help stabilize the components.

A mid-mounted engine is located between the rear of the passenger compartment and the rear suspension. It is also called a mid-engine.

A few vehicles mount their engines in the rear of the vehicles. Some are located between the passenger compartment and the rear suspension. These are called mid-mounted engines (or simply mid-engines) and are typically mounted transversely. They are used in compact, high-performance, rear-wheel-drive sports cars. The front of the vehicle can be low and sloped to maximize aerodynamics. The weight of the powertrain near the center of the vehicle places the center of gravity near the vehicle midpoint. This improves steering and handling for fine sports car performance. The most rare configuration is an engine mounted at the true end of the vehicle.

ENGINE MOUNTS An engine mount attaches the engine to the chassis and absorbs the engine vibrations.

Engines usually have two or three engine mounts to attach the engine to the frame and to isolate the vibration of the engine from the chassis and passenger compartment (Figure 8-5). There may be additional mounts that hold the transmission or transaxle and also help support the engine. The engine will have a top-engine mount that may look quite

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different from the one shown in Figure 8-4. Some mount at the very front of the engine and attach to the front radiator cross member (Figure 8-6). A lower engine mount on a transverse-mount engine may attach to either the back of the engine or the front of the transaxle (Figure 8-7).

Engine mount With bushings

Figure 8-5 This top-engine mount has two bushings to support the engine vertically and horizontally.

Figure 8-6 This top-engine mount attaches to the front cross member and the front of the engine.

Figure 8-7 This lower engine mount actually attaches at the front of the transaxle, very close to the engine.

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The rubber bushing has voids Figure 8-8 The voids in the bushings allow a looser attachment to the case. This allows the engine to vibrate and the mount to isolate those vibrations from the chassis.

Types of Engine Mounts Many engine mounts are simply rubber bushings in a metal casing. The rubber bushing absorbs the engine vibrations. The rubber is attached to the housing with some slack to allow movement within the case (Figure 8-8). The rubber may have voids to allow more movement within the mount. Hydraulic engine mounts use two chambers filled with fluid and an orifice in between to dampen the vibration of the engine. It takes some time and energy to displace the fluid from one chamber to the other as the engine moves. This helps absorb the engine vibration. They look and function very similarly to suspension shock absorbers (Figure 8-9). Some hydraulic engine mounts are electronically controlled. When the engine is idling, the engine mounting should be very soft to allow the engine to run as smoothly as possible during its low-load condition. Once the engine is driving under a load, stiffer dampening must occur to isolate the harsher movements from the chassis. To achieve that exceptionally smooth idle, more and more vehicles are using electronically controlled hydraulic engine mounts. In one example, the two hydraulic chambers are connected by a large and a small orifice. When the PCM determines that the engine is idling, it actuates a vacuum motor that opens the normally closed larger orifice. This allows more fluid flow and softer dampening to absorb the shaking of the engine at idle. Only the smaller valve is open during engineloaded conditions to provide the stiffer dampening needed to isolate engine vibration.

REMANUFACTURED ENGINES It is a trend in today’s automotive industry to replace seriously damaged engines with remanufactured or new units rather than overhaul the existing engine in the shop. Remanufactured engines are available from vehicle manufacturers and other suppliers (Figure 8-10). They will come with the internal components of the engine fully assembled and adjusted. Beyond that, the engines you receive may vary significantly. You can purchase a crate engine with or Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Hydraulic engine mount

Figure 8-9 This hydraulic engine mount looks very much like a shock absorber. Its function is quite similar as well.

Figure 8-10 The crate engine comes fully assembled, less the accessories. Some engines come more complete than others.

without cylinder heads. Some will come with new oil and water pumps and covers. In other cases, it is your responsibility to replace these components as warranted by the vehicle. Many crate engines will come as relatively bare engines with no covers or new accessories. All sensors, brackets, hoses, and tubing will be transferred from the old engine to the new. There are several advantages to installing a remanufactured engine. A crate engine comes fully assembled and carries a written warranty. That means that if the “new” engine suffers damage within the warranty period, the supplier will provide a new unit. If a technician rebuilt an engine in the shop and it came back within a few thousand miles and another engine mechanical problem, the shop would be responsible for making it right for the customer. This would cost the shop the technician’s labor and the cost of all the new parts to repair the damage. It is also often more cost-effective to install a reman engine rather than overhaul one in-house. A supplier that provides crate engines has a production shop of sorts. The technicians who work there overhaul engines every day and all day. They are very efficient at this. The supplier is also able to source parts in high volume for significant discounts.

A BIT OF HISTORY The idea of supplying remanufactured engines rather than overhauling existing ones is relatively new. In the 1980s, for example, most shops were rebuilding all their engines. Technicians were well practiced at the fine measuring required for professional overhauls. Many shops were still performing cylinder head service or “valve jobs” in-house as well. Now several shops have let much of the engine overhaul machining tools deteriorate or have sold them to machine shops where most of the engine machining is now done. Many “old-timers” and young enthusiasts alike miss the more frequent opportunities to build an engine.

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AUTHOR’S NOTE Many students are disappointed to learn that engine overhaul is not a common task in most general automotive repair shops. If engine overhaul is something you are interested in, you can make that a priority when looking for work. There are still many shops out there that specialize in engine repair. You can also consider working for an engine manufacturer.

A technician in a shop that overhauls an engine a few, or even a dozen, times a year will take longer to do the same work. The shop may not be able to source the discount parts that are available, especially to a high-volume consumer. The machining work that may need to be done at a local machine shop also adds cost and time to the overhaul. Sometimes when you are beginning the disassembly of an engine, it becomes apparent that the damage is so extensive that a remanufactured engine would definitely be cheaper (Figure 8-11). A hole in the engine block from a piston that let loose would make that engine cheaper to replace than to repair. You may not make a decision until you have taken the engine apart and evaluated it. Other shops simply follow the policy of installing crate engines whenever possible. There are reasons not to install remanufactured engines. For some vehicles, reman engines are not readily available or may be cost prohibitive (Figure 8-12). It is difficult to locate remanufactured engines for many low-volume import engines, for example. The condition of the vehicle and the desire of the customer may well warrant the cost of a thorough in-house overhaul. In some cases, the customer may want a new engine from the manufacturer despite the cost. This may be either a truly new or a remanufactured engine, as made available by the particular manufacturer. In other cases, the vehicle may

Figure 8-11 After finding piston and ring pieces in the oil pan, this shop decided that a crate engine would be more cost-effective. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 8-12 This high-mileage engine needs some major mechanical work. A reman engine is not readily available. The customer likes the vehicle so much that he or she has chosen to give the engine a thorough in-house overhaul.

be in such poor condition that it is not worth installing a new crate engine. The customer could also be in a financial situation that does not allow him or her to purchase a new engine. As we will discuss during our short block service discussions in a later chapter, you may be able to perform satisfactory, though minimal, repairs on a high-mileage engine. This sort of work may buy the customer the time he or she needs to be able to purchase a new engine or a new vehicle. By the time you complete your study of this text, you should feel confident in your ability to make these sorts of judgment calls.

SUMMARY ■

■ ■ ■ ■

Most front-wheel-drive engines are mounted transversely. Many rear-wheel-drive engines are mounted longitudinally. Some sports cars have mid-mounted engines. Engine mounts absorb the engine vibrations. Many engine mounts are either rubber or hydraulic.

■ ■ ■ ■

Electronically controlled hydraulic engine mounts can produce a very smooth idle. The engine has mechanical attachments to many other systems. Remanufactured engines are available for many popular engines. Crate engine may be a cost-effective alternative to an in-house overhaul.

REVIEW QUESTIONS Short-Answer Essays 1. List the types of engine configurations. 2. Explain the advantages of a transverse-mounted engine.

6. Explain the operation of the electronically controlled engine mount. 7. Explain the benefit of the electronically controlled engine mount.

3. Explain the advantages of a mid-mounted engine.

8. Explain two examples when you would be likely to install a remanufactured engine.

4. Explain the purposes of engine mounts.

9. Describe two benefits of a remanufactured engine.

5. Describe the operation of the hydraulic engine mount.

10. Describe why you might choose to overhaul an engine in-house.

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Fill-in-the-Blanks 1. A _______________ engine is mounted between the rear of the passenger compartment and ahead of the rear suspension. 2. A transverse engine assembly allows better _______________ because it is lighter. 3. A longitudinally mounted engine is usually used on four-wheel-drive and _______________ vehicles. 4. The two most common types of engine mountings are the longitudinal and the _______________. 5. The _______________ engine mounts work like a shock absorber. 6. Rubber engine mounts have _______________ to allow more movement within the mount. 7. _______________ _______________ hydraulic engine mounts can become firmer when the engine is driving under a load. 8. Remanufactured engines come with a _______________. 9. A remanufactured engine is also called a(n) _______________ engine. 10. The decision to install a remanufactured engine or overhaul an engine in-house may be made by _______________, the shop management, or the _______________.

Multiple Choice 1. The most common type of engine installation in a front-wheel-drive vehicle is. A. longitudinal. C. mid-mount. B. transverse. D. rear. 2. The most common type of engine installation in a rear-wheel-drive vehicle is. A. rear. C. transverse. B. mid-mount. D. longitudinal. 3. Technician A says that a transverse engine is usually coupled to a transaxle. Technician B says that most front-wheel-drive vehicles use longitudinally mounted engines. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Technician A says that a mid-engine is naturally faster than a longitudinally mounted engine. Technician B says that a mid-engine installation can improve vehicle handling. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. A rubber engine mount has voids to make the mount. A. softer. C. last longer. B. stiffer. D. resist twisting. 6. A hydraulic engine mount moves fluid through a. A. pintle. C. canister. B. solenoid. D. orifice. 7. Technician A says that an electronically controlled hydraulic engine mount can improve idle quality. Technician B says that these mounts can help isolate engine vibration during hard acceleration. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that it may be a shop policy to install a remanufactured engine rather than overhaul an engine in-house. Technician B says that some engines are damaged badly enough that it is not cost-effective to repair them. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. A crate engine may come with a new _______________ installed. A. A/C compressor C. Both A and B B. Power-steering D. Neither A nor B pump 10. A reason to install a remanufactured engine may be. A. cost. B. warranty. C. time savings. D. all of the above.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 9

CYLINDER HEADS

Upon completion and review of this chapter, you should understand and be able to describe: ■

■ ■ ■ ■ ■

The design of a valve, including an explanation of the stem, head, face, seat, margin, and fillet. The reasons for burned valves. The causes of valve channeling. The different types of valve seats. The reasons for adding Stellite to valve seats. Valve seat recession and its causes.

■ ■ ■ ■ ■

The purposes of valve stem seals, and the different types of these seals. The results of worn valve stems and guides. The different combustion chamber designs. The combustion process. How combustion chamber design can affect exhaust emissions and engine performance.

Terms To Know Burned valve Chamber-in-piston Channeling Eddy currents End gases Face Fillet Free-wheeling engine Head Hemispherical chamber Integral valve seats Interference engine

Margin Off-square Pentroof combustion chambers Poppet valves Quenching Skin effect Squish area Stellite Stem necking Stratified charge Surface-to-volume (S/V) ratio

Swirl chambers Tumble port Turbulence Valve float Valve guides Valve job Valve seats Valve seat insert Valve seat recession Valve spring Valve stem Wedge chamber

INTRODUCTION Proper combustion requires the engine to “breathe” properly. The air intake system directs air to the throttle body. From the throttle body, the intake air is directed through the intake manifold, through cylinder head, and past the intake valves into the combustion chambers. Once in the combustion chambers, the air-fuel mixture is ignited, and the resulting power output is affected by chamber design. Finally, the spent gases are expelled from the combustion chambers, past the exhaust valves, and out through the exhaust manifold and exhaust system. The intake and exhaust manifolds, cylinder head, valves, and rocker arms must all work together to move the air-fuel mixture in and out of the combustion chambers and expel the exhaust gases. In this chapter, we discuss cylinder heads and related components Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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such as valves, valve seats, and valve guides. Discussion of the typical system failures and their causes is also included. Today’s technician must be able to identify a failed component and determine the cause of the failure. Although lack of lubrication and overheating are the most common causes of component failure, all engines will exhibit some form of normal wear between moving parts. A technician must be able to classify component wear as normal or abnormal. If abnormal wear is determined, the cause must be identified and corrected before the engine is reassembled.

CYLINDER HEADS On most engines, the cylinder head contains the valves, valve seats, valve guides, valve springs, and the upper portion of the combustion chamber (Figure 9-1). In addition, the cylinder head has passages to allow coolant and oil flow through the head. Many modern engines have overhead camshafts (OHCs). In these cases, the cylinder head also houses the camshaft(s) and all of the valvetrain components. The cylinder head is attached to the block above the cylinder bores. This mating surface must be flat and have the correct surface finish. The cylinder head gasket is installed between the cylinder head and the block. It has the difficult task of sealing in the extreme forces of combustion and preventing internal or external leaks of oil or coolant. The cylinder head is made of cast iron or aluminum alloy. It is common for engine manufacturers to use aluminum alloys to cast the head and mate it to a cast-iron block. The difference in thermal expansion between the cylinder head and block creates radial stress that must be withstood by the head gasket. The gasket must be able to withstand scrubbing or even shearing during uneven expansion and contraction while maintaining its seal. The head gasket must be able to seal the combustion chamber even when one component expands differently than the other. Head-gasket failures can cause serious drivability concerns and engine damage. When the head gasket fails, it frequently allows coolant to enter the combustion chamber and also admits combustion gases into the cooling system. The burning coolant causes white, sweet-smelling smoke to be emitted from the tailpipe and will often cause misfire in the affected cylinder. In extreme cases, it can hydraulically lock the engine and cause extensive piston and cylinder damage. In most cases, the coolant passing across the oxygen sensors will destroy them. Many technicians replace the oxygen sensors after a head-gasket failure or at least warn the customer that the sensors may fail in the near future. The combustion gases in the cooling system cause Exhaust camshaft Hydraulic lash adjuster

Rocker arm

Intake camshaft

Valve spring retainer Valve spring

Intake port

Exhaust port

Exhaust valve

Valve stem seal

Intake valve

Figure 9-1 Typical OHC cylinder head components. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Heads

excessive pressure and air pockets in the system that frequently result in engine overheating and boiling over. Other times the symptoms may include erratic heater operation and engine temperature, consistent or intermittent overheating, rough running, misfiring (especially at start-up), excessive pressure in the cooling system, bubbles in the coolant overflow and coolant overflow from the tank, coolant loss without an external leak, or low compression on two adjacent cylinders. A blown head gasket can also allow coolant to mix in the oil, creating a fluid in the lubrication system that closely resembles a coffee milkshake. The oil’s lubricating and corrosion protection properties are diminished. Driving the vehicle with this condition can cause extensive engine damage. A cracked cylinder head can often cause the same symptoms as a blown head gasket. Occasionally, the crack in the head gasket or cylinder head is very small and will cause less dramatic symptoms. When the engine is cool, the metals in either of the suspect parts contract and enlarge the crack. Coolant may leak into the affected cylinder and foul the spark plug or cause small amounts of white smoke to exit the tailpipe. A classic symptom of a cracked cylinder head (or a small crack in the head gasket) is misfire on a cylinder accompanied by a little white smoke for about one minute after start-up. The white smoke also smells like coolant, not regular exhaust. Make sure that you do not confuse this white smoke with the normal condensation cloud that is emitted through the exhaust on a very cold day. Then the engine heat can cause enough expansion in the metal to seal the gap, and the engine may run perfectly for the rest of the day. Prompt repair of a vehicle exhibiting any of these symptoms is essential to prevent more severe engine damage. Overheating typically causes failure of the head gasket or a crack in the cylinder head. Often, the white smoke will billow from the tailpipe, making diagnosis straightforward. In other cases, very little smoke will be visible, and further testing will be needed to determine the cause of the overheating or misfire. The combination of an aluminum cylinder head and a cast-iron block with coolant circulating between them presents the problem of electrolysis. This is the chemical action producing a small electrical charge in the coolant. It exists when two dissimilar metals are touching the same fluid. As the coolant ages, it becomes acidic and the chemical additives that prevent electrolysis are used up. This is when electrolysis accelerates. Electrolysis will eat away at the aluminum components in the cooling system, including the cylinder head. Proper cooling system maintenance reduces the impact of electrolysis on aluminum components.

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Intake and Exhaust Ports The intake and exhaust ports cast into the cylinder head are carefully machined to match the flow of air from the intake manifold and out to the exhaust manifold. Some cylinders have Siamese ports, meaning that two cylinders share the same opening. This is not an ideal design but may be used to save space or cost. Intake ports may use a hump in them to increase air velocity, thus increasing volumetric efficiency. When the intake ports are on one side of the head and the exhausts on the other, the head is called a crossflow cylinder head design. This adds to the volumetric efficiency of the head, especially during valve overlap. As the intake valve opens, the incoming air is drawn into the moving air across the chamber from the exhaust flow (Figure 9-2). Non-crossflow designs have a much harder time filling the combustion chamber fully with air. Exhaust airflow out of the chamber may actually provide resistance to incoming air as it is pushing out in the opposite direction of the incoming air. The proximity of the hot exhaust gases to the intake charge also has a tendency to heat (and therefore reduce the density of ) the intake charge, reducing the volumetric efficiency.

Camshaft Bore The camshaft(s) on an overhead-cam engine has a bore machined into the head to house the camshaft. The top halves of the bores are caps or a cap housing that bolts to the head (Figure 9-3). On some engines, the bores may be fixed, and you can slide the camshaft Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Camshaft bearing cap

Cylinder head Camshaft Exhaust valve

Intake valve Air out

Air in

Figure 9-2 The momentum of airflow helps draw in a fresh charge; in a crossflow chamber this is particularly effective.

Figure 9-3 These soft aluminum camshaft caps serve as the cam bearing surface. In this case, there are no actual cam bearings or bearing inserts.

AUTHOR’S NOTE Many enthusiasts port and polish their heads during a performance overhaul. A die grinder can be used to polish the surface of the intake and exhaust passages and enlarge the actual ports to better match the opening of the manifold. This is called port matching. Some enthusiasts continue to enlarge the ports beyond the opening. This is called porting. Care must be taken when porting because removing metal from this area makes the walls thinner. Manufacturers have spent countless hours designing the flow through these ports, however; so take care not to change the basic flow design.

into place from either the front or rear of the head. Overhead camshafts sometimes use bearings. More often the integral bearing surface is the soft aluminum of the head. Oil passages lead into these bores to provide essential lubrication. If the cam bores are damaged, the head usually requires replacement, though in some cases the bores are machined oversize and inserts can be installed. Poppet valves control the opening or passage by linear movement.

The head is the enlarged part of the valve.

The face is the tapered part of the section of the valve head that makes contact with the valve seat.

Valves Modern automotive engines use poppet valves (Figure 9-4). The poppet valve is opened by applying a force that pushes against its tip. The camshaft lobes work to open the valves through the components of the valvetrain. Closing of the valve is accomplished through spring pressure. The valve as a whole has many parts (Figure 9-5). The large-diameter end of the valve is called the head. The angled outer edge of the head is called the face and provides the contact point to seal the port. The seal is made by the valve face contacting the valve seat in the cylinder head. The valve seat is press fit into the cylinder head or is an integral part of the head. To provide a positive seal, the valve face is cut at an angle. The angle is usually 458, though some manufacturers may use a 308 angle on some valves and seats. The angle causes the seal to wedge tighter when the valve is closed and allows free flow of the air-fuel

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Cam lobe Lash pad adjuster

Cam follower (bucket) Spring

Seal

Valve keeper groove

Valve stem

Stem

Guide

Valve

45° valve face

Margin

Head

Figure 9-4 Typical poppet valve configuration using an overhead camshaft.

Figure 9-5 The parts of the valves.

mixture when the valve is open. The valve face and seat must both be precisely machined to the correct angle and width to provide good sealing. Pits, corrosion, or carbon on either surface can result in leakage of compression and combustion forces. The area between the valve face and the valve head is referred to as the margin. The margin allows for machining of the valve face and for dissipation of heat away from the face and stem. The margin adds structure to the valve. If it is cut too thin during refinishing, the valve will burn or become misshapen and leak cylinder pressure. The valve stem guides the valve through its linear movement. The stem also has valve keeper grooves machined into it close to the top. These grooves are used to hold keepers that retain the valve springs. The stem rides in a valve guide located in the cylinder head. The head of the intake valve is typically larger than the exhaust valve’s. This is because maximizing intake valve size is considered more important than the exhaust valve. There is only so much area in the combustion chamber to locate the valves, and the larger the intake valve, the smaller the exhaust valve has to be. Smaller exhaust valves are able to work efficiently because the exhaust is being forced out of the chamber by the upward movement of the piston and by the heat generated by combustion; thus they are less sensitive to restrictions, whereas the air-fuel charge is being pulled into the cylinder by vacuum alone, and restrictions will reduce the engine’s efficiencies. Larger intake valves reduce the restrictions and improve volumetric efficiency. Most valves are constructed of high-strength steel; however, some manufacturers are experimenting with ceramics. Most valve heads are constructed of 21-2N and 21-4N stainless steel alloys; 21-2N alloy is commonly used in original equipment exhaust valves, and 21-4N is a higher grade of stainless steel containing more nickel. One of the primary concerns in valve construction and selection of alloys is the operating temperatures to which they are subjected. Combustion chamber temperatures can range from 1,5008F to 4,0008F (828C to 2208C). The types of material used to construct the valve must be capable of withstanding these temperatures and dissipating the heat rapidly. For every 258F (148C) reduction in valve temperature, the valve’s burning durability is doubled. There are several alloys available for valve construction that will increase the valve’s burning durability. An alloy that is being used by many manufacturers is Inconel. Inconel is constructed from a nickel base with 15 to 16 percent chromium and 2.4 to 3.0 percent titanium.

The margin is the material between the valve face and the valve head.

The valve stem guides the valve through its linear movement.

Shop Manual Chapter 9, page 390

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Chapter 9

One-piece valves do not weld the head to the stem like twopiece valves. The advantage of twopiece valves is that two different metals can be used to construct the head and the stem.

The fillet is the curved area between the stem and the head.

Valve construction design is also an important aspect for controlling heat. A valve can be constructed as one piece or two piece. One-piece valves run cooler since the weld of a two-piece valve inhibits heat flow up the stem. Two-piece valves allow the manufacturer to use different metals for the valve head and stem. In addition to alloy selection, manufacturers design the valve and cylinder head to dissipate heat away from the valve (Figure 9-6). Most of the heat is dissipated through the contact surface of the face and seat. The heat is then transferred to the cylinder head. About 76 percent of the heat is transferred in this manner. Most of the remaining heat is dissipated through the stem to the valve spring and on to the cylinder head. To increase the transfer of heat through the stem, some stems are filled with sodium. Turbocharged, supercharged, or other high-performance engines may use sodium-filled valves for their excellent heat dissipation quality and decreased weight. A sodium-filled valve has a hollow stem that is partially filled with metallic sodium (Figure 9-7). When the valve opens, the sodium splashes down toward the head and picks up heat. When the valve closes, the sodium moves up the stem, taking heat away from the hottest area of the valve, the head. The heat is transferred from the stem to the guide and then dissipated in the coolant passages around the guide. Sodium-filled valves should not be machined; if you were to cut through the valve, the sodium could explode. These valves should be replaced when reconditioning the head. Many manufacturers use chrome-plated stems to provide additional protection against wear resulting from initial engine starts when oil is not present on the valve stem. In addition, chrome works to protect against galling when cast-iron guides are used. If the valve stem is reground, the chrome plating will be removed. In this case, either the valve will have to be replated or a bronze guide must be used. The fillet is the curved area between the stem and the head. It provides structural strength to the valve. The fillet shape also affects the flow of the air-fuel mixture around the valve. A valve with a steeply raked fillet (called a tulip valve) has better flow than a valve with a flatbacked fillet. Fillet shape is only a factor while the valve is opening; after the valve is completely open, the fillet shape has very little effect on airflow. Although not normally considered a wear area, the fillet must be thoroughly cleaned. Carbon will build up in this area, causing the flow to be disrupted. Excessive carbon in this location can be an indication of worn valve stem seals or guides. A wire brush is usually required to remove carbon buildup on the fillet.

Valve spring Sodium

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Water jacket Water jacket Valve stem

Water jacket

Valve head

Figure 9-6 Heat must be removed from the valve.

Figure 9-7 The hollow valve is partially filled with sodium. When the valve closes, the sodium splashes up to help take heat away from the head and into the stem.

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Aluminized Valves. Aluminized valves provide increased valve life by reducing the effects of corrosion. Small particles of aluminum are fused to the valve head, causing a reaction that makes the surface corrosion resistant. Aluminized valves should not be reconditioned, because this process removes the coating from the head.

Determining Valve Malfunctions It is not enough to be able to recognize a failed valve. It is very important to determine the cause of the malfunction to prevent a repeat failure. Different types of failures are usually caused by identifiable conditions. Deposits on Valves. Excessive carbon buildup on valve stems is a relatively common problem on modern vehicles (Figure 9-8). This can be caused by excessive valve stem temperatures due to increased clearance between the valve guide and the valve stem. Deposits may increase as the valve seals wear and allow more oil into the guide, which can then bake onto the back of the valve. The use of improper or contaminated oil also leads to the formation of carbon deposits on the valve stems. The carbon buildup shown on the valve in Figure 9-8 affects engine performance. First, the mass of carbon restricts airflow into the combustion chamber and the loss of air intake reduces power. Second, the weight of the carbon commonly causes valve float at higher rpms. Valve float occurs when the springs can no longer hold the valve closing consistent with the profile of the cam lobe. Instead of closing swiftly with the drop of the camshaft lobe, the valve floats over the ramp and hangs open at higher rpm, when the momentum is greater. This causes engine misfire. Another common symptom of carbon buildup affects starting in the morning or when the engine is cold. The engine will typically start and stall two or three times and then start and run roughly for a few seconds. What happens is that the fuel injected into the intake is absorbed by the sponge-like carbon during the first couple of starting attempts. Then when the carbon becomes saturated with fuel, the vehicle starts and runs roughly, until the excess fuel is drawn out of the carbon. Burned Valves. A burned valve is identifiable by a notched edge beginning at the margin and running toward the center of the valve head (Figure 9-9). The most common cause of a burned valve is a leak in the sealing between the valve face and seat. At the location of the leak, the valve will not cool efficiently. This is because the heat from the valve head cannot be transferred to the valve seat and cylinder head. As the area increases in temperature, it begins to warp. The warpage results in less contact at the valve seat and compounds the problem of heat transfer. The resultant heat buildup melts the edge of the valve.

Figure 9-8 Carbon buildup on the neck of the valve interferes with breathing.

Valve float is a condition that allows the valve to remain open longer than intended. It is the effect of inertia on the valve.

Burned valves are actually valves that have warped and melted, leaving a groove across the valve head.

Figure 9-9 Burned valves are characterized by a groove from the face toward the fillet.

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Exhaust leaks allow cool air to flow past the valve. This cools the valve too fast, changes its structure, and reduces its burning durability.

Since heat transfer is dependent upon full contact of the valve face to the seat, anything preventing this contact can result in a burned valve. This includes weak valve springs, carbon buildup, worn valve guides, and valve clearance adjusted too tight. Additional causes of burned valves include preignition, exhaust system leaks, and failure of the cooling system. Not all overheating conditions result in burned valves. The metal of the valve head may become soft and form into a cup shape (Figure 9-10). The force applied by the springs to seat the valve, combined with combustion pressures, deforms the valve head.

Valve cupping is a deformation of the valve head caused by heat and combustion pressures.

Channeling. Under normal conditions, the fillet area of the valve should be the hottest area (Figure 9-11). The temperature around the valve edge should be the coolest. If the valve does not seat properly, the temperature is not transferred to the cylinder head. The area not contacting the seat becomes the hottest area of the valve head (Figure 9-12). The area with the hottest temperature will melt away, developing a channel. Channeling usually occurs just prior to valve burning. Channeling is generally due to four main causes:

Channeling is referred to as local leakage caused by extreme temperatures developing at isolated locations on the valve face and head.

1. Flaking off of deposits from the valve 2. Extensive valve face peening due to foreign material lodged between the valve face and seat 3. Corroded valve face 4. Thermal stress of the cylinder head, resulting in radial cracking Metal Erosion. Metal erosion is identified by small pits in the valve face that usually cannot be removed by valve grinding (Figure 9-13). This erosion is generally caused by coolant entering the combustion chamber. The chemical reaction etches away the face material. This condition can also occur if some chemicals enter the combustion chamber. These chemicals can come in the form of coolant system conditioners, oil additives, and fuel additives.

In a free-wheeling engine, valve lift and angle prevent valve-topiston contact if the timing belt or chain breaks.

When a timing belt or chain breaks, the pistons and crankshaft will quickly stop moving, but the valvetrain will stop moving almost immediately. If an engine is designed so that the valves could possibly touch the piston when this happens (because a valve is fully open and the piston is at TDC), it is called an interference engine.

Breakage. Breakage of the valve can occur due to valve and piston contact. In a free-wheeling engine, valve lift and angle prevent valve-to-piston contact if the timing belt or chain breaks. In an interference engine, this can be the result of timing chain or belt breakage. Interference designs are commonly used because they offer improved fuel efficiency, increased power output, and lower emissions. However, if the valve timing components fail, the valve can contact the top of the piston or another valve. This contact may cause the valve to break or be drawn into the combustion chamber. If this occurs, major engine damage results. If the engine you are working on has experienced this type of failure, inspect the head and block carefully for cracks and other damage. The head must usually be replaced when this type of failure occurs.

1200°F (649°C)

Figure 9-10 Excessive heating of the valve can lead to cupping.

1450°F (788°C)

1250°F (677°C)

Figure 9-11 Normal valve temperatures as heat is dissipated through the face and seat.

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Area of leak Excessive pitting Heat damage 1550°F (843°C) 1650°F (899°C) 1450°F (788°C)

Pitting not removed 1250°F (677°C)

1200°F (649°C)

Figure 9-12 Improper face and seat contact results in improper heat dissipation.

Margin ground off

Figure 9-13 Metal erosion of the valve.

Other than valve-to-piston contact, valves may also experience fatigue and impact breaks. A fatigue break is a gradual breakdown of the valve due to excessive heat and pressure. Impact breakage can result from the valve face being forced into the valve seat with excessive force. Impact breakage can be the result of excessive valve clearance, valve springs with excessive pressure, loss of valve keepers, or any condition that can result in stem necking. Necking is identified by a thinning of the valve stem just above the fillet (Figure 9-14). The head pulls away from the stem, causing the stem to stretch and thin. This condition is caused by overheating or excessive valve spring pressures. In addition, necking can be caused by exhaust gases circling around the valve stem. The corrosive nature of these gases and the action resulting from the swirl eat away the metal of the valve stem. Necking resulting from this action is caused by anything resulting in increased exhaust temperatures, including the following: ■ Improper ignition timing ■ Improper air-fuel mixtures ■ Overloading ■ Improper gear ratio in the final drive ■ Exhaust restriction An additional cause of valve breakage is referred to as off-square seating or tipping. If the valve does not seat properly, it may flex as it attempts to set into the valve seat. This flexing weakens the stem and eventually may lead to its breakage (Figure 9-15).

Wear

Stem necking is a condition of the valve stem in which the stem narrows near the bottom.

Valve guide

Cylinder head Stem necking

Breakage Wear Strikes here

Figure 9-14 A valve with a necked stem must be replaced.

Figure 9-15 Tipping of the valve in the guide can keep the valve from seating properly, resulting in breakage near the fillet.

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Chapter 9

Valve face Valve seat

1/2° to 1° interference angle

Figure 9-17 The valve face contacts the valve seat to seal the combustion chamber. The face and seat may be cut at different angles to create an interference angle. This allows the valve to seal with greater seating pressure.

Figure 9-16 A valve with a scored stem must be replaced to prevent premature failure of the valve seal.

Off-square seating or tipping refers to the seat and valve stem not being properly aligned. This condition causes the valve stem to flex as the valve face is forced into the seat by spring and combustion pressures.

Shop Manual Chapter 9, page 396

The valve seat provides the mating surface for the valve face.

Integral valve seats are part of the cylinder head. Valve seat inserts are pressed into a machined recess in the cylinder head.

Off-square seating can be caused by worn valve guides, distortion of the valve seat, improper rocker arm alignment, and weak valve springs. Valve Stem Wear. When visually inspecting the valve stem, look for galling and scoring (Figure 9-16). Either of these can be caused by worn valve guides, carbon buildup, or offsquare seating. Also look for indications of stress. A stress crack near the fillet of the valve indicates excessive valve spring pressures or uneven seat pressure. Stress cracks near the top of the stem can be caused by excessive valve lash, worn valve guides, or weak valve springs. Inspect the tip of the valve stem for wear and flattening. These conditions can be caused by improper rocker arm alignment, worn rocker arms, or excessive valve lash. Separation of the tip from the stem can be caused by these same conditions.

Valve Seats When the valve closes, it must form a seal to prevent loss of compression and combustion pressures. The valve face rests against the valve seat to accomplish this task (Figure 9-17). In addition to sealing compression pressures, the seat and face provide a path to dissipate heat from the valve head to the cylinder head. There are two basic types of valve seats: integral and removable inserts. Integral valve seats are machined into the cylinder head. The seat is induction hardened to provide a durable finish. Most aluminum cylinder heads (and many cast-iron cylinder heads) use valve seat inserts that are pressed into a recessed area (Figure 9-18). Common materials used in seat insert construction include cast iron, bronze, and steel alloys. Cast-iron inserts are used to repair cast-iron heads not originally equipped with seat inserts. Bronze inserts are typically used in aluminum cylinder heads. Bronze inserts are claimed to have better heat transfer, thus prolonging valve life. Steel alloys are available in several grades of stainless steel and with several grades of hardness. It has been commonly thought the harder the valve seat the better. The material used for the valve’s seat should be matched to the material used in its face; otherwise, less than recommended heat transfer and increased wear can

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Cylinder Heads

occur. One of the hardest seats is made of Stellite. The Stellite is applied to the valve seat to protect against oxidation and corrosion, and for added wear resistance. The seat is also induction hardened to provide a durable finish. Seat hardening is done by an electromagnet using induction to heat the valve seat to a temperature of about 1,7008F (9308C). This hardens the seat to a depth of about 0.060 in. (1.5 mm). The greatest advantage of integral seats is their ability to transfer heat. Integral seats run about 1508F (838C) cooler than seat inserts. The valve seat must be finished properly and cut to the specified width. Typically, the intake seats are approximately 1/16 in. and the exhaust seats about 3/32 in. Always check the manufacturers’ specifications when refinishing valve seats. The exhaust seat is a little wider because it has to dissipate more heat after being open during the end of the power stroke. The seat width is critical to proper cooling and sealing. The seat should be narrow enough to provide a high seating force from the valve spring. If the seat is too wide, the valve will not seat with enough force to chip away any carbon developing on the seat. It can also allow the valve to run cooler than designed, which can allow carbon to develop on the seat. The seat must be wide enough to allow extreme heat to dissipate during the short time that the valve is closed. If the seat is too narrow, the valve will burn or cup over time because it will run too hot. Seat Recession. Over time, valve seats have a tendency to recede further down into the head. This places the valves further into the head so that when the valves open there is not as much open area for air to flow; power is reduced. You can inspect for this before disassembling a cylinder head; simply look at each of the valves and make sure they are at the same level in the head. This measurement is called the installed height. There are three common causes of valve seat recession (Figure 9-19). The first is due to the pressure and heat in the combustion chamber causing local welding of the valve face and valve seat. When the valve is opened again, it forces a breaking of this weld, resulting in the removal of metal. In the past, this action of local welding was controlled by adding lead to the fuel. The lead would be the subject of the welding and breaking instead of the valve face and seat. To counteract the damage to valves and valve seats as a result of the loss of lead, most manufacturers use very hard valve seats. The second leading cause of valve recession is sustained high engine speeds. The third cause is weak valve springs. Both high engine speeds and weak valve springs cause valve recession in the same manner. Under these two conditions, the valve rotates faster than normal. This results in excessive grinding between the valve face and seat. If the valve face is a harder material than the seat, the seat will recede.

Figure 9-18 A valve seat insert.

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Stellite is a hard-facing material made from a cobalt-based material with a high chromium content.

Valve seat recession is the loss of metal from the valve seat, causing the seat to recede into the cylinder head.

Figure 9-19 Valve seat recession.

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Shop Manual Chapter 9, page 396

The solution for seat recession is to install hard valve seats and use high-quality valves. In addition, spring dampeners should be used to reduce chatter.

Valve Guides Valve guides support and guide the valve stem through the cylinder head.

Valve guides may be integral to the head or they may be pressed in. Cast-iron cylinder heads typically use integral valve guides. Holes are drilled down through the head where the valves will ride. On aluminum heads, the holes are bored oversized and guide inserts are pressed into the head. The guide inserts are usually cast iron or bronze (Figure 9-20). While bronze is a softer material, it has a natural lubricating quality that helps it resist wear. The guide ensures that the valve rides straight up and down and contacts the valve seat accurately. When valve guides wear, the valve can wobble in the head and the valve face-to-seat sealing is compromised. The wobbling of the stem also reduces valve seal contact and distorts the seals. Guide wear allows leakage past the valves and seals and reduces compression and power. Wear can also cause stress cracks and breakage near the fillet. The guides are machined to provide just the right amount of clearance between the guide and the stem of the valve. The clearance is typically 0.001 to 0.003 in., though some manufacturers may specify more clearance. If the fit is too loose, the valve will wobble and provide poor seating, and if it is too tight, the valve can stick. The small clearance allows a thin film of oil to lubricate the valve and guide. Too much clearance allows oil to be pulled past the intake valve seal as the valve wobbles, resulting in oil consumption and bluish gray smoke out of the tailpipe. This is most noticeable at start-up, during extended idling, or on deceleration when vacuum is high. The guides have coolant passages around them, helping the valves dissipate heat.

Valve Seals To control the amount of oil allowed to travel down the valve stem to provide lubrication, valve stem seals are used. These seals are constructed of synthetic rubber or plastic and are designed to control the flow of oil, not prevent it. There are three basic types of valve stem seals: O-ring, umbrella, and positive seal. The O-ring seal is basically a square-cut seal made of rubber (Figure 9-21). The valve stem has a groove machined near the top to accept the O-ring. The O-ring forms a seal between the valve stem and the spring retainer. A shield is also used to deflect oil away from the valve stem. Umbrella seals fit over the valve stem (Figure 9-22). The seal provides a tight fit around the valve stem and a loose fit around the guide. This design allows the seal to move up and down with the valve.

Figure 9-20 Insert valve guides. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Heads Keepers (valve locks)

Keepers (valve locks)

Spring retainer

Spring retainer

O-ring

Spring

Spring

Umbrella stem seal

Figure 9-22 The umbrella seal is installed over the top of the valve stem.

Figure 9-21 O-ring valve stem seal.

Figure 9-23 Positive valve seal designs.

Positive seals are generally constructed of rubber with a Teflon insert (Figure 9-23). The design fits the valve guide snugly with either a light spring, spring clip, or press fit. Positive seals are considered by many to be the best type of valve stem seal. It is possible to replace umbrella or O-ring seals with positive seals. If the original guide was not cut for a positive seal, it can be cut to accept the seal.

CYLINDER HEAD COMPONENT RELATIONSHIPS All components of the cylinder head associated with valve opening and seat (the valve, spring, guide, and seat) must work together to accomplish their designed tasks. Wear, damage, or problems in one component will have an effect on the other components. If the valve stem or guide is worn, there will be excessive movement of the valve inside the guide (Figure 9-24). This movement will translate to improper seating and possible burning of the valve. Figure 9-24A shows oil leaking past a worn intake valve guide. Atmospheric pressure pushes the oil into the air-fuel mixture. When the intake valve opens and the mixture is drawn into the cylinder, the oil is burned with the air-fuel charge. This results in oil consumption and blue smoke from the tailpipe. Figure 9-24B shows an exhaust valve with a worn guide allowing oil to be sucked by the guide due to venturi action. This too will result in oil consumption and blue smoke. A valve that is not seating properly will cause poor engine performance. Both compression and combustion gases will be lost through the leakage. Lost compression reduces

Engine oil Engine oil

Intake port

Oil pulled into combustion chamber by vacuum (burning oil)

Exhaust port

Oil pushed out of combustion chamber by residual pressure

Figure 9-24 Worn valve guides can translate to improper valve sealing and oil consumption. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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A valve job includes refinishing or replacing the valves and seats and any other worn components in the valvetrain. A valve spring connects to the valve by a keeper and retainer, and pulls the valve back into the valve seat, thus putting the valve in a closed position where no fuel or air can pass through it. Wedge chamber design locates the spark plug between the valves in the widest portion of the wedge in the cylinder head. Quenching is the cooling of gases as a result of compressing them into a thin area. The quench area has a few thousandths of an inch clearance between the piston and combustion chamber. The squish area of the combustion chamber is the area where the piston is very close to the cylinder head. The airfuel mixture is rapidly pushed out of this area as the piston approaches TDC, causing a turbulence and forcing the mixture toward the spark plug. The squish area can also double as the quench area. Turbulence is the movement of air inside the combustion chamber. A high surface-to-volume (S/V) ratio results in higher HC emissions. The S/V ratio is a mathematical comparison between the surface area of the combustion chamber and the volume of the combustion chamber. A typical S/V ratio is 7.5:1.

the potential power of combustion, and when combustion gases leak past a valve, they are not exerting force on top of the piston to produce power. A small leak by the valve seat will rapidly turn into a burned valve. You will feel poor valve sealing as misfire and a loss of power in the engine. You may also hear popping in the intake or exhaust system as the pressurized combustion gases are allowed in through a leaking valve. Thorough reconditioning of the cylinder head components is often called a valve job. It consists of repairing or replacing all of the necessary components in the valvetrain to provide trouble-free operation for extended mileage, typically 100,000 miles or more. A complete valve job requires that the cylinder head(s) be removed from the engine. If the valve seals and/or valve springs are faulty, a repair may be made with the cylinder head still installed on the engine. Replacing these valve seals with the head installed was common with older engines where the seals did not last very long.

AUTHOR’S NOTE During the cylinder head reconditioning process, all valvetrain components must be machined or replaced so they meet the engine manufacturer’s specifications. An unsuccessful cylinder head reconditioning job may be defined as one that did not provide a reasonable mileage interval before some valvetrain component failed. It has been my experience that unsuccessful cylinder head reconditioning jobs are usually caused by failure to make sure that all valvetrain components are within manufacturer’s specifications. For example, the technician may have done an excellent job of reconditioning the valves, seats, and guides, but the condition and measurements on the valve springs were overlooked.

COMBUSTION CHAMBER DESIGNS The size, shape, and design of the combustion chamber affect the engine’s performance, fuel efficiency, and emission levels. Manufacturers can use several different combustion chamber designs to achieve desired engine efficiency results.

Wedge Chamber The most common method of creating a wedge chamber is to use a flat-topped piston and cast a wedge into the cylinder head (Figure 9-25). Wedge chamber design locates the spark plug between the valves in the widest portion of the wedge. The air-fuel mixture is compressed into the quench and squish areas, resulting in a turbulence that mixes the air-fuel mixture. The squish area squishes the air-fuel mixture into the center of the combustion chamber as the piston moves up toward Top Dead Center (TDC). This added turbulence helps mix the air-fuel mixture, cools it, and helps promote a faster burn once the ignition system begins combustion. The quench area cools the end gases in the chamber to prevent them from igniting before the intended flame front engulfs them. The squish and quench area of the combustion chamber gives it a lot of surface area compared to the volume. This high surface-to-volume (S/V) ratio of the combustion chamber has a negative impact on emissions. A higher S/V ratio contributes to greater hydrocarbon emissions as the fuel clings to the relatively cooler walls and exits the combustion chamber unburned in the form of hydrocarbons. The wedge combustion chamber design does not promote high volumetric efficiency. Air does not easily reach the hidden pocket of the wedge and the added turbulence reduces airflow, particularly at higher rpm. Another design method is to use flat chambers in the cylinder head and to offset the cylinder bores. This results in the piston approaching the cylinder head at an angle and produces the same basic functions of a wedge chamber.

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Cylinder Heads

Hemispherical Chamber The hemispherical chamber is designed in a half-circle with the spark plug located in the center of the dome (Figure 9-26). The valves are located on an incline of 608 to 908 from each other. The hemi-head design provides an even flame front because the spark plug is centered. The design also allows for easy “breathing” of the engine because the valves are located across from each other. During the period of valve overlap, the stream of airflow out the exhaust valve helps pull air in through the intake valve. The area inside the hemi chamber is wide open and fills easily. The hemi design has a very low S/V ratio. A disadvantage to this design is that the combustion chamber creates little turbulence. While this helps volumetric efficiency at higher rpm, it can allow the hot gases to ignite without a spark, causing uncontrolled combustion. To prevent this, some manufacturers may use a domed piston.

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Placing the crown of the piston this close to the cooler cylinder head prevents the gases in this area from igniting prematurely. The term hemi may be used for an engine with hemispherical combustion chambers.

Pentroof Chamber Pentroof combustion chambers are a very common design for today’s multivalve engines. They were first used in the 1980s and have grown in popularity since. The inverted-V shape of the chamber provides a low S/V ratio, resulting in lower emissions (Figure 9-27). These chambers are similar to the hemispherical head and share most of the advantages of that design. The pentroof chamber allows for larger valves and provides some turbulence.

Pentroof combustion chambers are a common design for multivalve engines using two intake valves with one or two exhaust valves and provide good S/V ratio.

Swirl Chamber To improve combustion efficiencies, swirl chambers are designed with a curved port that causes the air-fuel mixture to swirl in a corkscrew fashion (Figure 9-28). The compression of this swirling mixture causes a thorough mixing of the gases, resulting in increased fuel economy and reduced exhaust emissions. Location of the valve and design of the chamber causes the swirl action.

Swirl chambers create an airflow that is in a horizontal direction.

Chamber-in-Piston The chamber-in-piston design locates the combustion chamber in the piston head instead of the cylinder head (Figure 9-29). The advantage of this chamber design is that the piston remains hot enough to provide proper vaporization of the air-fuel mixture. This design is used on many diesel engines.

A chamber-in-piston is a piston with a dish or depression in the top of the piston.

Spark plug Valve Valve

Cylinder block

Cylinder head

Pentroof chamber

Piston

Figure 9-25 Wedge combustion chamber design.

Figure 9-26 Hemispherical combustion chamber design. Notice the domed piston.

Figure 9-27 Pentroof combustion chamber design.

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Valve spring

High swirl and turbulence of air-fuel mixture as piston moves downward

Combustion chamber

Intake valve Exhaust valve closed

Chamber

Intake valve open

3 mm (0.112 in.) mask to valve clearance

Masked area promotes swirling action of air-fuel mixture

Piston

Figure 9-29 Chamber-in-piston combustion chamber design.

Figure 9-28 Swirl combustion chamber design.

B

A

Figure 9-30 (A) Standard uniform-flow and (B) fast-burn tangential-flow combustion chambers.

Fast Burn

Tumble port combustion chambers use a modified intake port design.

An eddy is a current that runs against the main current.

A faster combustion can be achieved by directing the incoming air-fuel mixture tangentially through the intake valve (Figure 9-30). This results in a turbulence that mixes the gases. An additional benefit of this design is the compression ratio can be increased without an increase in octane requirements. This is because the fast-burn design has less potential for knock.

Tumble Port Tumble port combustion chambers use a modified intake port design, resulting in a tumbling vortex mixture burning technique (Figure 9-31). This design uses the principle of eddy currents by using a volume of air that runs against the main current to provide a tumbling condition. Benefits include increased fuel economy and reduced hydrocarbon emissions. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Heads Conventional port

193

Tumble port

Modified

Conventional port –90 CA

–60

–30

BDC

30

60

90 Tumble velocity weak

Tumble velocity moderate

Tumble port

Figure 9-31 Comparison of conventional and tumble port designs.

Stratified-Charge Chambers The stratified-charge combustion chamber is actually two chambers contained within the cylinder head (Figure 9-32). The smaller chamber (prechamber) is located above the main chamber and has its own intake valve. A very rich air-fuel mixture is delivered to the prechamber, where the spark plug is located. The rich mixture is very easy to ignite. At the same time, a very lean mixture is delivered to the main chamber. At the completion of the compression stroke, the spark plug fires to ignite the rich mixture in the precombustion chamber. The burning rich mixture will ignite the lean mixture in the main combustion chamber. The first manufacturer to mass-produce the stratified-charge engine was Honda. It used the engine from 1975 to 1987 with the compound vortex controlled combustion

Intake valve rich mixture

A stratified-charge engine has two combustion chambers. A rich air-fuel mixture is supplied to a small auxiliary chamber, and the very lean air-fuel mixture is supplied to the main combustion chamber.

Intake valve lean mixture

Intake manifold Precombustion chamber Combustion chamber

Figure 9-32 Stratified-charge combustion chamber. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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(CVCC) design. A three-barrel carburetor was used. Two barrels supplied the lean mixture for the main combustion chamber, while the third barrel supplied the prechamber with the rich mixture.

THE COMBUSTION PROCESS

The unburned gases are called end gases.

Combustion is the chemical reaction between fuel and oxygen that creates heat and pressure. It is a closely controlled burning of the air and fuel. Spark ignition occurs before top dead center on the compression stroke. The hot, compressed air-fuel mixture is ignited, and a flame front develops. For normal combustion to occur, the air-fuel mixture must be delivered in the proper proportions and mixed well, the spark must be timed precisely, and the temperatures inside the combustion chamber must be controlled. The flame can then move quickly and evenly (propagate) across the combustion chamber, harnessing the power of the fuel as heat. Pressure builds steadily as the gases expand from heat. The peak of this pressure develops around 108 ATDC (After Top Dead Center) to push the piston down on the power stroke. The heat produced inside the combustion chamber must be controlled to reduce the possibility of preignition or detonation. The expansion of gases forces the unburned gases to be packed tighter and made hotter. Heat is dissipated through the spark plug case and threads in addition to the top of the piston, the walls of the combustion chamber, and the engine coolant (Figure 9-33). The design of the combustion chamber has a huge impact on the process of combustion. The heat absorption of the end gases can be increased by creating some turbulence within the combustion chamber and by proper design of the squish and quench areas (Figure 9-34). As the gases swirl around, they come into contact with the walls of the combustion chamber or the top of the piston. Turbulence prevents the gases from becoming stagnant. Stagnant gases will only dissipate heat from the outer edges, allowing the center to become very hot. Turbulence also causes the flame to burn faster. The turbulence can be promoted by piston top design and the squish area of the chamber. The squish area causes the gases to be squirted out of an area of the chamber as the piston compresses the gases. As the gases burn, the end gases are packed into the quench area of the chamber. This thins the gases and allows them to dissipate heat faster. The quench area design affects the emission output of the engine. As previously discussed, to prevent the end gases from

Squish area

Turbulence

Figure 9-33 During proper combustion, the flame spreads steadily across the chamber and heats all of the gases.

Quench area

Figure 9-34 Quenching and turbulence are used to cool the temperatures of the end gases to prevent autoignition.

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Cylinder Heads

igniting on their own, heat is removed from them. This unburned mixture has a thickness of about 0.002 in. to 0.010 in. (0.1 mm to 0.3 mm). This thin layer of gases never burns, because the temperature is too low, and it is expelled into the exhaust system as unburned hydrocarbons. The larger the combustion chamber, the more the surface area for the formation of the skin effect. Manufacturers have reduced hydrocarbon emissions by redesigning the quench area. Reduction of hydrocarbons can be accomplished by increasing the height of the quench area. This increases the temperature of the end gases and reduces the thickness of the skin effect. Another means is by eliminating undesirable quench areas. This is done by removing sharp corners and pockets. Cylinder head gasket redesign and improved fit have eliminated many of these undesired quench areas. Finally, skin effect has been reduced by lowering the compression ratio of the engine. This is not desirable from a performance point of view, but it was necessary to reduce emissions. Most engine manufacturers reduced the output of their engines during the late 1970s to the mid-1980s. Better understanding of the combustion process, chamber designs, fuels, and emission controls has made a return of higher compression engines possible.

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Skin effect is a small layer of unburned gases formed around the walls of the combustion chamber.

A BIT OF HISTORY With the great amount of moving parts within the engine, it is truly surprising how well it works. Unfortunately, engines requiring carbon-based fuels pollute the air and use a nonreplenishable fuel source. Today, most manufacturers are attempting to design a reliable, cost-efficient electric vehicle. This idea is not new. During the early years of the “horseless carriage,” over one-third were driven electrically.

Preignition Preignition occurs when a flame is ignited in the combustion chamber prior to the spark plug firing. Preignition results in a light knocking or rattling sound during acceleration at operating temperature. It is usually the result of hot spots in the chamber. This can be caused by excessive combustion chamber pressures. An excessively high compression ratio causes the temperature of the fuel charge to be raised above its flash point. A change in compression ratio can occur anytime there is a decrease in combustion chamber volume. This can be caused by excessive carbon buildup. Other things that change compression ratio include piston design and milling of the cylinder head, the block, or both. Another cause of preignition is the use of excessively low octane fuel. The octane required to properly operate the engine is based on the compression ratio of the engine. The higher the ratio, the higher the octane required. The result of preignition is high pressures within the combustion chamber before the piston reaches TDC. This pressure forces the piston to reverse direction too soon, wasting useful combustion energy. It is possible to blow a hole in the top of the piston near the outer edge as a result of preignition (Figure 9-35).

Detonation Normal combustion takes about 3 milliseconds (3/1,000 of a second). Abnormal combustion, detonation, is more like an explosion, occurring as fast as 2 millionths of a second (2/1,000,000 of a second). The explosive nature of detonation can cause serious engine damage. Detonation occurs when combustion pressures develop so fast that the heat and pressure will “explode” the unburned fuel in the rest of the combustion chamber. Before the primary flame front can sweep across the cylinder, the end gases ignite in an uncontrolled burst (Figure 9-36). The dangerous knocking results from the violent explosion. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Detonation Preignition

Figure 9-35 Piston damage caused by abnormal combustion.

Figure 9-36 End gases explode before the flame can expand across the chamber. The hot pressure spike knocks the piston so hard that it can blow a hole in it.

Detonation causes piston and ring damage, bent connecting rods and worn bearings, top ring groove wear, blown head gaskets, and possibly complete engine failure. Common causes of preignition and detonation are the following: ■ Deposits in the cooling system around the combustion chamber ■ Engine overheating ■ Too hot a spark plug ■ An edge of metal or gasket hanging into the combustion chamber ■ Fuel with too low an octane rating ■ An inoperative or clogged exhaust gas recirculation (EGR) system ■ Too much ignition timing advance ■ Lean air-fuel mixtures (when there is less-than-desired fuel mixed with air) ■ Carbon buildup in the combustion chamber ■ A faulty knock sensor ■ Excessive boost pressure from a turbocharger or supercharger

Misfire Misfire is another type of abnormal combustion. When an engine misfires, it means that one or more of the cylinders are not producing their normal amount of power. The cylinder(s) is unable to burn the air-fuel mixture properly and extract adequate energy from the fuel. The misfire may be total, meaning that a flame never develops and the air and fuel are exhausted out of the cylinder unburned. Hydrocarbon emissions increase dramatically. Misfire may also be partial when a flame starts but sputters out before producing adequate power due to a lack of fuel, compression, or good spark. When an engine is misfiring, the engine bucks and hesitates; the misfire is often more pronounced under acceleration. Technicians normally call this a miss or a skip. Extended misfire can destroy the catalytic converter by overloading it with fuel and causing it to overheat. Misfire can be caused by ignition or fuel-system faults as well as engine mechanical problems. Typical engine mechanical faults that cause misfire are as follows: ■ Burned or leaking valves ■ Valve-stem or valve-back carbon buildup ■ Weak or broken valve springs Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Heads ■ ■ ■ ■ ■

Worn valve guides or lifters Broken, worn, or bent rocker arms or pushrods Worn camshaft(s) Improper valve timing Worn pistons or rings

A BIT OF HISTORY The Honda Insight and the Toyota Prius were the first hybrid cars to be introduced in the North American market. As the “hybrid” name suggests, these cars have two power sources to supply torque to the drive wheels. These power sources are a mechanical power source from the engine and an electric power source from batteries and electric motors. These cars may be referred to as parallel hybrids or even series-parallel because power may be supplied to the drive wheels from the engine or from the electric motor. An onboard computer system controls the power source to the drive wheels. When the vehicle is decelerating, the electric motor acts as a generator to help charge the batteries. These batteries do not require charging from an external source. Several other manufacturers have introduced hybrid vehicles after the success of the Toyota and Honda versions. The internal combustion engine technology in these vehicles has since been transferred over to other nonhybrid vehicles.

MULTIVALVE ENGINES Many of today’s engines are designed with more than two valves per cylinder. An engine may use multiple valves to increase volumetric efficiency. The easier an engine can breathe, the more efficient and powerful it can be. A multivalve design allows more air-fuel mixture to enter the combustion chamber faster and helps the engine expel the spent exhaust gases. The most common multivalve engine is the four-valve-per-cylinder design (Figure 9-37). Other designs use an extra intake valve, either a three-valve or a five-valve combustion chamber. One such variation is the use of a smaller second intake valve used as a jet valve. The jet valve directs air from above the throttle plates into the combustion chamber. At low engine speeds, this air causes a swirling action in the combustion chamber (Figure 9-38). The resultant turbulence increases the efficiency of the burn. Since the air inlet to the jet valve is above the throttle plates, the amount of air entering the valve decreases as engine speed increases. Intake valve Jet valve

Exhaust valves

Intake valves

Figure 9-37 Multivalve cylinder head.

Figure 9-38 Some multivalve engines use a jet valve to increase the burn effectiveness at low engine speeds.

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SUMMARY ■

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■

■

■

On most engines, the cylinder head contains the valves, valve seats, valve guides, valve springs, and the upper portion of the combustion chamber. The poppet valve is opened by applying a force that pushes against its stem. Closing of the valve is accomplished through spring pressure. The valve as a whole has many parts. The largediameter end of the valve is called the head. The angled outer edge of the head is called the face and provides the contact point to seal the port. The area between the valve face and the valve head is referred to as the margin. The stem guides the valve through its linear movement. Manufacturers use several methods to dissipate the heat from the valve. First, the contact surface of the face and seat is used to transfer the heat to the cylinder head. The second method is through the stem, valve guide, valve spring, and on to the cylinder head. A burned valve is identifiable by a notched edge beginning at the margin and running toward the center of the valve head. Metal erosion is identified by small pits in the valve face and is generally caused by a chemical reaction in the combustion chamber. Breakage of the valve can occur due to valve and piston contact, valve springs that are too tight, loss of valve keepers, any condition that can result in stem necking, and off-square seating. The continual movement of the valve may result in wear on the portion of the stem traveling in the guide. As the stem wears, the oil clearance

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■ ■

■ ■

■

increases, resulting in excessive oil being digested into the combustion chamber and the formation of deposits on the valve. The valve seat is located in the cylinder head and provides a seal when the valve face contacts it. It also provides a path to dissipate heat from the valve head to the cylinder head. There are two basic types of valve seats: integral and removable inserts. Integral valve seats are machined into the cylinder head. Most aluminum cylinder heads (and many cast-iron cylinder heads) use valve seat inserts that are pressed into a recessed area. Valve guides support and guide the valve stem through the cylinder head. There are two types of valve guides used: insert and integral. Insert guides are removable tubes that are pressed into the cylinder head; integral guides are machined into the head. Valve seals control the amount of oil allowed to travel down the valve stem to provide lubrication. The size, shape, and design of the combustion chamber affect the engine’s performance, fuel efficiency, and emission levels. The wedge and the pentroof combustion chamber designs are popular on modern gasoline engines. Preignition is a form of abnormal combustion that occurs when a hot spot in the combustion chamber causes autoignition of the air-fuel mixture before the spark. Detonation occurs when the end gases autoignite after the spark. Detonation’s damaging force can blow holes in the top of pistons.

REVIEW QUESTIONS Short-Answer Essays 1. List the purpose of the following components: Cylinder head Intake valve Exhaust valve Valve seat 2. List and describe the common types of combustion chambers. 3. List the common causes for the following valve failures: burned valves, channeling, metal erosion, and breakage.

5. List the causes of valve seat recession. 6. What are the differences between interference and free-wheeling engines? 7. List and describe the functions of the parts of a valve. 8. Explain why you should not refinish or machine sodium-filled valves. 9. List and describe the three common types of valve stem seals. 10. Describe the purpose of the valve guides and the difference between integral and insert types.

4. Explain the advantages of the pentroof combustion chamber. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Heads

Fill-in-the-Blanks 1. The area between the valve head and the valve face is called the valve _______________. 2. _______________ control the flow of gases into and out of the engine cylinder. 3. Valve stem _______________ control the amount of oil allowed to travel down the valve stem and provide lubrication. 4. When the valve closes, it must form a seal to prevent loss of compression. The _______________ rests against the valve seat to accomplish this task. 5. _______________ guides are removable tubes that are pressed into the cylinder head. _______________ guides are machined into the head and are a part of the cylinder head. 6. Most of the heat is dissipated from the valve through the contact area between the valve face and _______________ _______________. 7. The most common cause of a burned valve is a leak in the sealing between the _______________ _______________ and seat. 8. Metal erosion is generally caused by _______________ entering the combustion chamber. 9. Necking is identified by a _______________ of the valve stem just above the _______________. 10. An engine may use multiple valves to _______________ volumetric efficiency.

Multiple Choice 1. The most common refinishing valve face angle is: A. 158 C. 458 B. 308 D. 608 2. Valve stem seals. A. eliminate oil leakage into the valve guides. B. are not used on newer engines. C. keep combustion gases from corroding the valve stem. D. control oil flow to the valve stem. 3. Each of the following is a likely cause of valve burning except: A. A faulty thermostat B. A leak between the valve face and seat C. Worn valve guides D. A thick valve margin

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4. Technician A says that the intake valve is often smaller than the exhaust valve. Technician B says that the exhaust valves can operate more efficiently because the air is under pressure when the exhaust valve opens. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Most of the valve’s heat is dissipated through the. A. face. C. stem. B. margin. D. fillet. 6. The advantages of the pentroof combustion chamber include each of the following except: A. Good turbulence B. A high S/V ratio C. High volumetric efficiency D. Centrally located spark plug 7. The skin effect causes. A. premature valve burning. B. preignition. C. flaking of the Stellite seats. D. high HC emissions. 8. _______________ occurs when another flame starts after the spark. A. Combustion C. Detonation B. Preignition D. Misfire 9. Technician A says that preignition is harmless. Technician B says that detonation can cause severe engine damage. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Each of the following is a likely cause of detonation except: A. Carbon buildup in the combustion chamber B. Engine overheating C. A lean air-fuel mixture D. Fuel with too high an octane rating

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CHAPTER 10

CAMSHAFTS AND VALVETRAINS

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■

■ ■ ■

The function of the valvetrain. The differences between overhead valve valvetrains and overhead camshaft valvetrains. The components of the valvetrain. The purpose and function of the camshaft. The relationship among the camshaft lobe design and lift, duration, and overlap.

■ ■ ■ ■ ■ ■

The benefits and limitations of valve overlap. The purpose of the lifters. The operation of hydraulic lifters. The purpose of pushrods. The common methods of mounting the rocker arms. Rocker arm geometry.

Terms To Know Advanced camshaft Camshaft bearings Camshaft lift Clearance ramp Duration Lifters Lobe separation angle Lobes

Pedestal-mounted rocker arm Pump-up Pushrods Retarded camshaft Rocker arm Rocker arm ratio Roller lifter

Shaft-mounted rocker arms Stud-mounted rocker arm Valve lift Valve overlap Valve spring Zero lash

INTRODUCTION Every component that works to open and close the valves is part of the valvetrain. Air must flow efficiently into and out of the cylinder head to supply maximum power. Proper breathing of the engine depends on the valves opening and closing at the correct time. All of the components that make up the valvetrain work together to perform this task. The camshaft(s) opens the valves for the correct amount of time and to the proper distance. The springs close the valves and must overcome tremendous momentum when the engine is spinning near the red line to hold the valves against the profile of the camshaft. The camshaft is mounted in the block in overhead valve engines. When the camshaft is mounted in the cylinder head, it is called an overhead camshaft engine. The other valvetrain components—pushrods, rocker arms, lifters, keepers, and valve rotators and retainers—will differ slightly depending on the engine design. Everything in the valvetrain is related and dependent upon each other; thus, a failure in the system can result in poor performance, engine noise, or mechanical failures. One stray 200

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Camshafts and Valvetrains

movement in the valvetrain, a stretched component, or a snapped lock can throw the whole assembly into a wrecked heap of parts.

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Shop Manual Chapter 10, page 456

Valvetrain Components The valvetrain components work together to open and close the valves. For proper engine operation, this function must be performed at the precise time without loss of motion. The components of the valvetrain vary depending on engine design. The common components include the following: ■ Camshaft ■ Lifters or lash adjusters ■ Pushrods ■ Rocker arms or followers ■ Valves ■ Valve springs ■ Valve keepers ■ Valve spring retainers ■ Valve rotators ■ Timing chain, belt, or gears ■ Camshaft and crankshaft sprockets ■ Variable valvetrain components

The valvetrain components work together to open and close the valves.

Shop Manual Chapter 10, page 456

Camshafts Simply stated, the camshaft is used to control valve opening (Figure 10-1). However, its function is actually more complicated. The camshaft also controls the rate of opening and closing, and how long the valve is open. The camshaft is precisely timed to the crankshaft to be sure the valves open at the correct time during their respective strokes. The camshaft spins at half the speed of the crankshaft to allow each valve to open only once during a complete engine cycle. One complete engine cycle means that the engine has rotated 720 degrees and that each of the cylinders has had one firing event. The camshaft may be driven by a gear, belt, or chain off the camshaft. Camshafts are designed differently depending on the type of lifter to be used with them. There are roller camshafts, hydraulic camshafts, and mechanical camshafts. The difference in the camshaft may be in the material used or in the shape of the lobe. Camshafts are usually constructed of nodular cast iron, although some high-performance engines use cast steel. Since roller lifter camshafts have the highest amount of load per square inch, most of these style camshafts are manufactured from forged steel billets. Some late-model engines have camshafts made from a steel tube (Figure 10-2). The lobes are bonded to the steel tube, and a nose piece is friction welded to the tube.

Figure 10-1 Typical camshaft design. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 10-2 A lightweight tubular camshaft used in a late-model V6 DOHC engine.

The lobes of the camshaft push the valves open as the camshaft is rotated. Camshaft lift is the valve lifter movement created by the rotating action of the camshaft lobe. Typical lobe lift of original equipment in the block camshafts is between 0.240 in. and 0.280 in. (6 mm and 6.6 mm). Valve lift is the total movement of the valve off of its seat, expressed in inches or millimeters.

Camshaft end play is controlled by a thrust plate at the front of the camshaft. This type of camshaft is more rigid than a camshaft made from cast or forged steel. The increased camshaft rigidity reduces engine vibration. The lobes of the camshaft push the valves open as the camshaft is rotated. There is usually one lobe for each intake and exhaust valve. The lobe design is a factor in determining how far the valve will open and for how long (Figure 10-3). The height of the lobe defines the amount of valve lift or opening. The amount of camshaft lift affects the amount of valve lift. Additional factors of valve lift include rocker arm ratio, pushrod deflection, and lifter condition. Camshaft lift is a measurement of the height of the lobe above the base circle. When an overhead camshaft engine does not use rocker arms, the camshaft lobe opens the valve directly; camshaft lift is then the same as the valve lift. Valvetrains that use rocker arms use mechanical advantage in the rocker arm design to multiply camshaft lift. Valve lift is an important factor in determining how well the engine can breathe (ingest the air-fuel mixture and expel it). The valve is a restriction to airflow into the combustion chamber. This is true until the valve is lifted about 0.300 in. (8 mm) off its seat. At this point, the valve offers very little restriction to airflow. However, there is still an advantage to increasing valve lift over 0.300-in. (8-mm). A typical amount of valve lift is 0.4 in.–0.55 in. (10.16 mm–13.97 mm). The longer the valve remains open after reaching the 0.300-in. (8-mm) lift, the better the airflow. Many manufacturers have increased the amount of lift in their camshafts to increase the amount of valve opening. Lift does not adversely affect fuel economy, Valve opening

Valve closing

Nose

Closing ramp Opening ramp Cam lift

24

15 Valve closes Clearance

Valve starts to open

Base circle Rotation

Figure 10-3 The lobe design determines how far the valve will open and for how long.

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Camshafts and Valvetrains

power, or emissions (as does excessive duration). For this reason, some manufacturers have maintained moderate duration of the camshafts and increased lift in an attempt to increase airflow. One of the limitations on maximum valve lift is the amount of travel of the valve spring. If the valve spring is required to travel a greater distance, its coils can bind. The camshaft duration is determined by the length of the slope of the lobe beyond the base circle. The wider and longer the lobe is, the longer the valve stays open. Camshaft duration is measured in degrees of crankshaft rotation. Intake valve duration may differ from exhaust valve duration. If a valve opens at top dead center (TDC) and closes at bottom dead center (BDC), the duration of the valve is 180 degrees. This is not practical for real-world engine operation. In actuality, the intake valve must open before TDC and close after BDC. The additional degrees of rotation must be calculated into the total duration degrees. If the intake valve opens 6 degrees before TDC and closes 12 degrees after BDC, total duration is 198 degrees of crankshaft rotation. Since duration allows more time for the air-fuel mixture to fill the combustion chamber, duration has more effect on engine performance and efficiency than any other valve timing specification. There are instances when an engine may require longer durations to perform a specified function; for example, the high-performance engines used in most racing applications require a camshaft with higher durations. This camshaft allows the engine to breathe at higher rpm. The drawback is that the engine performs poorly at lower engine rpms. Variable valve timing technology allows a manufacturer to have the ability to design the engine for good performance, low emissions, and good economy. All of this can be done with only one design for the camshaft. By changing the timing of the camshaft, the lift and duration will change when compared to their relationship with the piston’s position. If a replacement camshaft is to be purchased, there are two methods used to measure duration. Society of Automotive Engineers (SAE) specifications are measured after 0.006 in. (0.15 mm) of lift on hydraulic lifter camshafts. Performance camshafts are usually measured for duration at 0.050-in. (1.25-mm) lift. An SAE-measured camshaft will have approximately 40 to 50 degrees more duration than a camshaft measured at 0.050-in. (1.25-mm) lift. This means that a camshaft with 220 degrees of duration at 0.006 in. has less-effective duration than a camshaft with 195 degrees of duration at 0.050 in. The design of the lobe also determines how rapidly the valve opens. The steepness of the ramp dictates how quickly the valve opens and closes. Clearance ramps are ground into the lobe to prevent the valvetrain components from hammering on each other. The clearance ramps are located between the base circle and the opening or closing ramps. The clearance ramps remove clearance in the valvetrain at a slower rate than the rate of lift (Figure 10-4). Most camshafts used with hydraulic lifters have a clearance ramp between 0.005 in. and 0.010 in. (0.13 mm and 0.25 mm). This ramp ensures that the lifter check valve is closed to provide a solid connection. At the end of the exhaust stroke and the beginning of the intake stroke, both valves are open at the same time. This is called valve overlap. The amount of overlap is defined by the camshaft lobe separation angle (Figure 10-5). The larger or wider the separation angle, the less overlap. A tighter or lower separation angle means that the valves will be open together for a longer time, providing more overlap. A wider separation angle, used on most passenger cars, is 112 to 116 degrees. A high-performance engine or highperformance camshafts may have a tighter angle in the range of 112–116 degrees. The lobe separation angle or spread is determined by finding the lobe centers of the intake lobe and the exhaust lobe and averaging the two values. The lobe center can be found by using a degree wheel and a dial indicator (Figure 10-6). The degree wheel indicates the number of degrees after TDC where the maximum amount of valve lift is achieved for the intake

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Camshaft duration is the amount of time the camshaft holds the valve open. It is measured in degrees of crankshaft rotation.

The area of the mechanical lifter camshaft from base circle to the edge comprises the clearance ramp. When both the intake and exhaust valves are open at the same time an engine has valve overlap. The lobe separation angle is the average of the intake and the exhaust lobe centers. It defines the amount of valve overlap. The tighter the angle (lower number of degrees), the more overlap the camshaft provides.

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Chapter 10 Lobe separation angle

Valve lift

Overlap Clearance ramp

Clearance ramp

Valvetrain clearance

Figure 10-4 The clearance ramp removes valvetrain clearance at a slower rate than valve lift.

Figure 10-5 The time, in crankshaft degrees, that both valves are open is overlap. This is defined by the lobe separation angle.

Figure 10-6 A degree wheel can be used to find the lobe centers.

An advanced camshaft has the intake valve open more than the exhaust valve at TDC. It is used to improve lowspeed torque. A retarded camshaft has the exhaust valve open more than the intake at TDC.

valve. The exhaust lobe centerline is determined in the same manner. The degree wheel is used to measure the number of degrees before or after TDC where the valve is fully opened. The lobe separation angle is the average of the two readings. For example, if the intake lobe center is 110 degrees after TDC and the exhaust lobe center is 120 degrees before TDC, the lobe separation angle is 115 degrees. If the intake lobe center is less than the lobe separation angle, the camshaft is advanced. An advanced camshaft has the intake valve(s) open more than the exhaust valve(s) at TDC. This type of camshaft is used to increase lower rpm performance for greater torque. Retarded camshafts are designed to have the exhaust valve open more than the intake at TDC. Valve overlap helps the engine breathe better, particularly at higher rpm. The movement of airflow out of the exhaust valve helps draw the fresh air in through the intake valve. The momentum of airflow helps fully clean the spent exhaust gases out of the chamber even after TDC. This stream of airflow also helps pull the intake charge into the chamber. This is called scavenging. Too much overlap at a lower rpm, however, can allow some of the fresh air-fuel mixture to flow out of the exhaust valve and some exhaust to flow back into the intake. This is called reversion and leads to a rough idle, increased emissions, and reduced fuel economy. When you have exhaust gases in the intake, it reduces engine vacuum and counteracts the intended effects of overlap. Production vehicles use

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Camshafts and Valvetrains

a wider separation angle to prevent the negative effects of reversion. Some engines using variable valve timing systems use two sets of camshaft lobes. At higher rpm, the camshaft lobes in use will provide greater overlap to improve volumetric efficiency and power. Some variable valve timing systems move the camshaft into a different position with regard to its timing. This will affect the performance and emissions of the engine significantly.

AUTHOR’S NOTE Aftermarket performance camshafts often produce an uneven or lopey idle accompanied by low vacuum. This is the result of reversion. If the engine is being designed for higher rpm performance, long overlap is essential, but be aware that you will sacrifice some low-rpm torque to achieve this goal. The fuel economy will suffer greatly, and emissions will typically be higher. Most camshaft upgrades are not legal for street use. They have a significant impact on emissions because of the long period of overlap and its resulting flow of intake charge out the exhaust. If you live in a state that performs tailpipe emissions testing, it is unlikely that a vehicle with a significantly modified camshaft will pass the emissions test. Any engine modification that increases the emissions of the vehicle is illegal for street use. Always refer to local laws and ordinances before performing modifications, especially if you are being paid to perform the services.

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Caution The Automotive Engine Rebuilders Association (AERA) recommends only a stock camshaft replacement on computer-controlled engines due to poor performance at some rpms. If you are replacing the camshaft on a computercontrolled engine with a non-OEM component, you may need to modify the computer, a few sensors, or both to make the engine operate correctly.

Some older designs of valvetrains used flat tappet camshafts. The camshaft lobes had a very slight taper of 0.0007 in. to 0.002 in. (0.0178 mm to 0.0508 mm) across their face (Figure 10-7). Along with offsetting the centerlines of the lifter and the lobe, this taper provided for lifter rotation. This was done to prevent premature wear, since the lifter’s edge was not riding on the edge of the camshaft lobe. Rotating the lifter helped dissipate nearly 100,000 psi (690 MPa) load on the lifter. Roller lifters are commonly used today. Roller lifters are indexed and do not rotate. Camshaft Bearings. The camshaft(s) rides in bearings or bearing surfaces on their journals. Oil pressure is fed through ports in the camshaft bearing bores. Like crankshaft main and rod bearings, camshaft bearings clearances are essential to good lubrication and adequate oil pressure. Camshafts that are installed within the engine block are usually fitted with full round bearings (Figure 10-8). These are one-piece bearings that are pressed into the block, and the journal of the camshaft is slid into place. A few overhead camshaft engines use split bearings with camshaft caps. Modern machining and oil improvements have made it possible for most manufacturers to eliminate the use of camshaft bearings in their overhead camshaft engines. In this case, the soft aluminum bore and caps serve as the bearing surface.

Camshaft bearings are required in most engines as a means of reducing friction between the camshaft and the cylinder block.

Shop Manual Chapter 10, page 448

The lobe taper is usually less than 0.001 in.

Clearance

+ Taper

+

The lifter bores are offset to allow rotation.

Figure 10-7 The taper of the camshaft lobes will provide lifter rotation to reduce wear.

Full round

Figure 10-8 Full-round camshaft bearings are used in engines with the camshaft in the block and in some overhead camshaft engines.

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Lifters Lifters are mechanical (solid) or hydraulic connections between the camshaft and the valves.

A solid lifter may be called a tappet or follower.

A roller lifter is a normal lifter with a rolling pin on the bottom to decrease friction.

Zero lash is the point where there is no clearance or interference between components of the valvetrains.

Lifters are mechanical (solid) or hydraulic connections between the camshaft and the valves. Lifters follow the contour of the cam lobes to lift the valve off its seat. Solid lifters provide a rigid connection, while hydraulic lifters use oil to absorb the resultant shock of valvetrain operation. Each lifter design has its advantages and disadvantages. Solid lifters require a specified clearance between the components of the valvetrain. Periodic adjustment is required to maintain this clearance. If the clearance is too tight, there is no room for expansion due to heat. This can result in loss of power and value burning. If the clearance is too great, excessive noise, or valvetrain clatter, may be generated. In addition to noise, a change of 0.001 in. (0.03 mm) in valve lash may result in about a 3-degree change in duration. The lifter must be adjusted periodically to compensate for wear in the valve and valvetrain components. This is often recommended every 30,000 or 60,000 miles. Check the specific maintenance schedule. You will adjust the valve to have some lash between the rocker arm and the valve tip. This allows for a margin of error in valvetrain operation and also allows for the diminishing clearance as the valvetrain components heat up and expand. Many consumers see periodic valve adjustment as a disadvantage; it represents more costly maintenance. Hydraulic lifters use oil to automatically compensate for the effects of engine temperature and valvetrain wear. Some engine manufacturers use a roller-type hydraulic lifter, commonly called a roller lifter, in an effort to reduce friction (Figure 10-9). This type of lifter is fitted with a roller that rides on the camshaft lobe. Friction is reduced since the lifter body is not rubbing against the camshaft lobe (Figure 10-10). Roller lifters can also be designed as solid lifters for high-performance and heavy-duty diesel applications. Roller lifters are accompanied by a roller camshaft, which typically has steeper opening and closing ramps. Roller lifters do not need to rotate in the lifter bore, because they operate with lower friction. The hydraulic lifter automatically maintains zero lash. When the hydraulic lifter is resting against the base of the camshaft lobe, the valve is in its closed position (Figure 10-11). In this position, the plunger spring maintains a zero clearance in the valvetrain (Figure 10-12). Oil supplied by the oil pump is pushed through the oil feed holes of the lifter bore and into the lifter body. Oil is able to enter the lifter body only when the lifter is in this position, since the feed through the engine block is not aligned with the lifter body when it is on top of the lobe. The oil passes through the body and enters the inside of the plunger through an oil passage on its side. The check valve allows oil to flow from the plunger into the body, but not from the body to the plunger. Oil continues to flow into the lifter until it is full. Pressurized oil is trapped in the lifter by the closed check valve. The spring under the plunger pushes the lifter body toward the camshaft lobe and the plunger Pushrod

Lifter body Guide surface

Roller

Cam lobe

Figure 10-9 A roller lifter from a latemodel engine.

Figure 10-10 Roller lifters reduce friction and wear by using a roller on the camshaft.

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207

Pushrod Plunger Oil hole

Body

Check ball (closed)

Check ball (open)

Plunger Return spring

High-pressure chamber

Oil hole

Metering valve

Retainer Ball

Lock ring Engine valve closed

Engine valve open

Figure 10-11 Hydraulic valve lifter operation comparison between valve open position and valve closed position.

Lifter body

Plunger spring

Plunger

Pushrod seat

Spring

Figure 10-12 The internal components of a hydraulic lifter.

toward the pushrod, removing any play in the valvetrain. The position of the check valve is determined by the pressure applied on the pushrod cap. This pressure is transferred from the closed valve through the pushrod to the cap. When the camshaft lobe attempts to raise the lifter body, the pressure on the cap and plunger is increased and the check valve closes, preventing the oil in the area below the plunger from escaping. Since the oil cannot be compressed, a rigid connection is formed, causing the plunger to raise the lifter body and open the valve. As the temperature of the engine increases, parts begin to expand, reducing the amount of clearances. This causes the plunger of the lifter to be held lower in the lifter body, causing some of the oil that was trapped below the plunger to leak out from the lifter body. In addition, when the lifter is moved up the block bore by the camshaft lobe, the pressures of attempting to open the valves push the plunger down in the body. This results in leakdown. When the lifter follows the cam lobe back to the base, the oil feed passages align and the lifter is filled with oil again. This process of filling and leakdown automatically adjusts the hydraulic lifter to compensate for temperature changes and component wear. You can hear faulty lifters; they cause significant valvetrain clatter as the valvetrain components clash against each other after taking up the unintended clearance. You can hear the noise that they make when they first start up; this is normal. The clattering should disappear within a few seconds as oil pressure fills the body. When lifters wear, it takes longer for them to fill after start-up. Eventually they will become unable to hold oil as the camshaft tries to open the valve. This will cause noisy valvetrain clatter and loss of power because the valves will not open fully. Solid lifters are often used in high-performance engines because they cannot pump-up. Since hydraulic lifters adjust automatically, they can overcompensate at higher engine speeds. At high engine rpm, valvetrain inertia causes the valves to open farther than what is accomplished by the cam lobe and rocker arm ratio. This valve float causes additional clearance to occur in the valvetrain. The lifter compensates for the additional clearance as it would under normal clearance corrections because the spring pushes the plunger up to take up the additional clearance. At this time, the body cavity fills with oil from the plunger cavity. The filling of the plunger cavity causes the lifter to be slightly longer than normal as it approaches the heel of the camshaft lobe. Again, the lifter compensates for this. On the next valve opening, the cavity is filled again and the cycle starts over. At high rpm, the lifter is unable to return to its normal size when it is

Lifter pump-up occurs when excessive clearance in the valvetrain allows a valve to float. The lifter attempts to compensate for the clearance by filling with oil. The valve is unable to close, since the lifter does not leak down fast enough.

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approaching the heel of the lobe. The result is that the valve can be held open. When the engine speed is reduced, lifter operation returns to normal.

OHC Valvetrain Designs Some overhead camshaft (OHC) engines use hydraulic lash adjusters (Figure 10-13). The lash adjuster works in the same manner as the hydraulic lifter. In some V6 DOHC valvetrains, the camshaft journals ride in cylinder head bores, and holders and holder plates retain the camshafts to the cylinder heads. The rocker arm shafts and rocker arms are mounted below the camshafts in the cylinder heads (Figure 10-14). Cam followers are often used on overhead camshafts where the cam sits directly over the valves. The follower, often called tappet, is just a round cup that sits on top of the valve and provides a wider base for the camshaft to push on (Figure 10-15).

Rocker arm

Intake camshaft

Steel-tube camshaft

Hydraulic lash adjuster

Roller rocker arm

Figure 10-13 Some overhead camshaft engines use hydraulic valve lash adjusters.

Hydraulic valve lash tensioner

Camshaft holder plate

Figure 10-14 This modern valvetrain uses hydraulic valve lash adjusters, roller rocker arms, and a tubular camshaft.

Adjusting shim

Follower/Bucket

Figure 10-15 This follower sits directly under the camshaft and has a shim that can be changed to make valve clearance adjustments.

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Often there are shims either under or on top of the followers that can be fitted to size to make the proper adjustment. These lifters also need periodic adjustment. There are a few manufacturers that use hydraulic followers. The hydraulic body sits under a cup (like a follower) and works just like a hydraulic lifter to constantly adjust valve clearance to zero.

Pushrods Overhead valve (OHV) engines, with the camshaft located in the block, use pushrods to transfer motion from the lifter to the rocker arms (Figure 10-16). Besides being a link to the rocker arms, some pushrods are also used to feed oil from the lifter to the rocker arms (Figure 10-17). The oil is sent up the hollow portion of the pushrod. Most pushrods are constructed from seamless carbon steel tubing. To decrease wear, some pushrods may have a hardened tip insert at each end. High-performance engines may use pushrods that are made of chromium-molybdenum tubular steel for increased strength. Chrome-moly pushrods may also have a thinner wall thickness to reduce weight and inertia. The bottom of the pushrod fits into a socket in the lifter. The recesses of the socket are deep enough to prevent the pushrod from falling out during operation. The top of the pushrod fits into a small cup in the rocker arm. Tolerances within the valvetrain generally allow some machining of the cylinder head without the need to correct pushrod length; however, if the deck surface of the cylinder head and/or the engine block is machined or if valve stem length is increased, it may be necessary to change the pushrods to maintain the correct valvetrain geometry. This is especially true on engines with nonadjustable valvetrains.

Pushrods connect the valve lifters to the rocker arms.

Rocker Arms The rocker arm is a pivoting lever used to transfer the motion of the pushrod to the valve stem. In overhead camshaft engines, the camshaft may operate the rocker arms directly (Figure 10-18). Rocker arms change the direction of the cam lift and spring closing forces, and they provide a leverage during valve opening. Most rocker arms are constructed of cast iron, cast aluminum, or stamped steel.

The rocker arm is a pivoting lever used to transfer the motion of the pushrod to the valve stem.

Rocker arm Valve spring Valve guide

Valve

Engine oil

Pushrod Pushrod Lifter

Camshaft

Figure 10-16 The valve lifter transfers force to the pushrod.

Figure 10-17 The pushrod can be used to deliver oil to the rocker arm.

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Chapter 10 Fulcrum (pivot point) B A Rocker arm ratio

1 1.5

C

Pushrod 0.300 in. lifter movement

Valve assembly

0.450 in. valve movement

Figure 10-18 This OHC head uses rocker arms with integral hydraulic lifters to open the valves.

The difference in the rocker arm dimensions from center to valve stem and center to pushrod is called the rocker arm ratio. It is a mathematical expression of the leverage being applied to the valve stem. Shaft-mounted rocker arms are used in a mounting system that positions all rocker arms on a common shaft mounted above the cylinder head. A stud-mounted rocker arm is mounted on a stud that is pressed or threaded into the cylinder head.

A pedestal-mounted rocker arm is mounted on a threaded pedestal that is an integral part of the cylinder head.

Figure 10-19 Rocker arms are designed to provide a mechanical advantage. The ratio is determined by comparing the distance from A to C to the distance from A to B. In this example, the ratio is 1.5:1.

The design of the rocker arm is such that the side to the valve stem is usually longer than the side to the pushrod (Figure 10-19). This design gives the rocker arms a mechanical advantage. The rocker arm ratio works with the camshaft lobe to provide the desired lift. The ratio of the distance is calculated by comparing the distance from the rocker pivot to the point where the rocker hits the valve tip to the distance from the rocker pivot to the point where the rocker contacts the pushrod. Divide the longer distance to the valve tip by the shorter distance to the pushrod to find the ratio. For example, if the distance to the pushrod is 1.00 in. (25.4 mm) and the distance to the valve tip is 1.50 in. (38.1 mm), divide 1.50 in. by 1.00 in. (38.1 mm by 25.4 mm). The answer is 1.50 in. (1.5 mm); the rocker ratio is stated as 1.50:1 or 1.5 mm:1 mm. If the camshaft lift is 0.3 in. (7.62 mm), multiply that by the rocker ratio to find the valve lift: 0.3 in. 3 1.50 in. 5 0.45 in. (7.62 mm 3 1.5 mm 5 11.43 mm) of valve lift. There are three common methods of mounting the rocker arm (Figure 10-20): ■ ■ ■

Shaft mounted Stud mounted Pedestal mounted

Shaft-mounted rocker arms are located on a heavy shaft running the length of the cylinder head. The shaft is supported by stands. Stud-mounted rocker arms are used on overhead valve engines. Each rocker arm is mounted on a stud. A split ball is used as a pivot point for the rocker. Pedestal-mounted rocker arms are similar to the studmounted assemblies, except the rocker pivots on a split shaft. Rocker Arm Geometry. When the valve is opened 50 percent of its travel, the rocker arm-to-stem contact should be centered on the valve stem (Figure 10-21). If the rocker arm is not centered, it will cause excessive side thrust on the stem. Rocker arm geometry does not usually need to be checked or corrected; however, if a different camshaft with a higher lift than the original camshaft is installed, rocker arm geometry will be affected. The higher lift causes the valve to move farther, causing the rocker arm tip to swing down

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Camshafts and Valvetrains Stud-mounted rocker arm

Shaft-mounted nonadjustable rocker arm Rocker arm

Rocker arm stud nut Fulcrum seat (ball pivot)

Rocker arm

Spacer Stand Oil hole

Hollow stud

Rocker shaft

Oil hole

Adjusting screw Attaching bolt

Locknut Rocker arm

Fulcrum Oil hole Stand

Rocker arm Fulcrum guide

Compression spring

Threaded pedestal Rocker shaft

Shaft-mounted adjustable rocker arm

Pedestal-mounted rocker arm

Figure 10-20 Common methods of mounting the rocker arm.

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farther in its arc. As the tip travels a greater distance, the tip moves away from the stem center. Other causes of incorrect rocker arm geometry include the following: ■ ■ ■ ■ ■

Shop Manual Chapter 10, page 453 The valve spring is a coil of specifically constructed metal used to force the valve to follow the profile of the camshaft and close fully. This provides a positive seal between the valve face and seat.

Cylinder head resurfacing Cylinder block deck resurfacing Sinking the valve seat Worn or incorrect pushrods Worn rocker arms

In engines that use pushrods, the angle of the rocker arm in relation to the pushrod is also important. Incorrect rocker arm geometry may result in the pushrod hitting the side of its passage in the cylinder head or the pushrod guide plate. In addition, on engines that use hollow pushrods to supply oil to the upper engine, incorrect rocker arm geometry may prevent proper lubrication. These engines have a small hole in the recessed cup that accepts the pushrod tip. When the opening in the pushrod aligns with the hole in the rocker arm, oil is sprayed over the rocker arms and valve springs. The holes should align when the rocker arm is in the lash position. As the rocker arm is moved to open the valve, the holes are no longer aligned and oil flow stops. Incorrect rocker arm geometry may cause the holes not to align properly and result in too much or too little oil flow. Any machining operations that alter the distance between the camshaft and the rocker arm may affect rocker arm geometry. Even changes to camshaft lift and duration can change the geometry. Usually the tolerances in the valvetrain will allow for some changes and machining without problems, but the geometry should be checked while rebuilding the engine. There are two basic functions of the valve spring: First, it closes the valve against its seat; second, it maintains tension in the valvetrain when the valve is open to prevent float. The spring must be able to perform these functions while withstanding temperature changes and vibrations. A valve spring is another vital component in the operation of the valvetrain. In today’s high-speed, high-performance engines, the valve spring becomes a very significant factor in efficiency and power output. The valve spring must be able to handle the challenge of opening and closing the valves 50 times per second at 6,000 rpm. After miles of use, the spring may lose its tension or break. The reciprocating motion of the valve produces a considerable inertia effect. Worn or weak valve springs may not have sufficient tension for the lifter to follow the camshaft lobe, resulting in valve float. Valve float causes the lifters to leave the camshaft lobe surface. In turn, this results in an abrupt seating of the valve and the lifter impacting the camshaft lobe. Valve float can result in excessive wear of the valve seat, lifter, camshaft, and valve. In addition, weak valve springs can prevent good heat transfer, resulting in burned valves and valve seat damage by bouncing the valve face against the seat. In some cases the piston can come in contact with the valve head. Weak valve springs usually have visible wear on their ends. To accomplish its functions, the valve spring can be designed with different characteristics and features. The most common designs include dual springs, dampers, and variable-rate springs. Dual springs are basically a set of two springs, with the smaller spring set inside the larger coil. The two springs have different diameters and lengths. The difference in sizes creates two different harmonic vibrations that cancel each other. Some manufacturers use a damper inside the valve spring to reduce harmonic vibrations (Figure 10-22). The damper is a flat, wound coil designed to rub against the valve spring. The rubbing effect reduces the vibrations. Variable-rate springs are designed with unequally spaced coils (Figure 10-23). This results in a spring that increases its rate of pressure as it is compressed. The closely wound coils are placed down toward the head. The more the spring is compressed, the more

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Camshafts and Valvetrains

Valve spring

Mechanical vibration damper

Figure 10-22 Damper spring.

Close-wound coils toward head

Figure 10-23 A variable-rate valve spring.

pressure it exerts for the distance compressed. For example, a variable-rate spring may exert an additional 40 pounds of pressure the first tenth of an inch it is compressed; the next tenth of an inch of compression will result in an additional 50 pounds of pressure; the next tenth of an inch of compression will result in an additional 60 pounds of pressure, and so forth. Along with different shapes and designs, different metals are used to construct valve springs. The steels used to construct a valve spring can vary from the very expensive H-11 tool steel used in Pro Stock drag racing to various grades of stainless steel. The type of steel determines the strength of the valve spring and its ability to transfer heat. Heat is one of the major contributing factors to valve spring fatigue. Oil flowing over the valve spring is the only cooling method used. The majority of the heat generated in the valve spring is the result of friction between the coils of the spring. Some valve spring manufacturers attempt to reduce the amount of friction by coating the valve springs. Common coatings include Teflon and SDF-1. Teflon sheds the oil, while SDF-1 retains the oil by use of a wettable matrix. In tests, a coated spring runs about 208F (118C) cooler than an uncoated spring.

A BIT OF HISTORY Quotes from a 1954 Buick owner’s manual: 1. Every 5,000 miles the distributor points should be cleaned and spaced. The proper gap setting is 0.0125 in. to 0.0175 in. 2. The spark plugs should also be cleaned and gapped every 5,000 miles. Standard gap adjustment is 0.030 in. to 0.035 in. 3. At 5,000-mile intervals, the timing should be checked and adjusted if necessary. This should be done with a timing light or synchroscope. 4. The voltage and current regulator should be adjusted properly in order to avoid burned ignition points or burned-out light units and radio tubes. This recommended automotive service is much different from the service required on modern vehicles that do not have ignition points or timing adjustments; spark plug replacement intervals are often 100,000 miles, solid-state voltage regulators are not adjustable, and radios have transistors in place of tubes.

AUTHOR’S NOTE Many years ago, when I was a novice technician, I unbolted my stock overhead camshaft and replaced it with a “hot” performance camshaft. I adjusted the valves but left the replacement springs that came with the kit in my toolbox to install later. The camshaft combined with my new headers made a very noticeable improvement in engine power. Months later, when I was on a long and fast drive, my engine started misfiring. When I pulled over, I could hear clatter from under the valve cover. When I removed the valve cover, I saw the broken spring. It would have been easier to have installed the replacement springs in the shop than to replace the broken one in the back lot of someone else’s garage in the rain.

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Keepers (valve locks)

Spring retainer

Spring

Umbrella stem seal

Valve rotators

Figure 10-25 The exhaust valves on this engine are fitted with valve rotators to help clean the valve face and seat.

Figure 10-24 Valve keepers lock the valve spring retainer in place.

Valve Spring Retainers and Rotators Valve springs are held in place by retainers locked onto the valves with keepers (Figure 10-24). The keepers lock onto the valve stem and are tapered so the retainer opening cannot fit over the keepers. The retainer may be a simple piece of steel to hold the spring in place. Other designs use a rotator built into the retainer. A rotator is used to turn the valve on its seat. It looks thicker than an ordinary retainer and is either ball or spring type. The ball type has small ball bearings that rotate on a ramped track in the assembly to turn the valve. The spring type has an unequal height spring to achieve the same effect. Often they are used only on the exhaust valves. It addition to helping clean the rotation, they help to more evenly dissipate heat to prevent hot spots, which cause burning and wear on the valve (Figure 10-25).

SUMMARY ■

■

■

■

■

The camshaft is driven by the crankshaft and timed precisely to provide valve opening at the correct times. The valvetrain components work together to open and close the valves. The common components include the camshaft, lifters or lash adjusters, pushrods, rocker arms or followers, and valves. Simply stated, the camshaft is used to control valve opening, the rate of opening and closing, and how long the valve will be open. The lobes of the camshaft push the valves open as the camshaft is rotated. The height of the lobe determines the amount of valve lift or opening. The design of the lobe will also determine the duration of valve opening. Lift can be expressed in two methods. The first is cam lift, which is the measured lift of the cam lobe. The second is valve lift. This is the cam lift multiplied by the rocker arm ratio to provide a specification for the amount of valve movement.

■

■

■

■

■

■

The camshaft lobes generally have a very slight taper, which works with offsetting the centerlines of the lifter to provide for lifter rotation. Lifters are mechanical (solid) or hydraulic connections between the camshaft and the valves. Lifters follow the contour of the cam lobes to lift the valve off its seat. Flat tappet lifters are designed to rotate in the lifter bore to reduce wear. Hydraulic lifters use oil to automatically compensate for the effects of engine temperature and valvetrain wear. Roller lifters create less friction than standard flat tappet lifters and use a different roller camshaft. OHV engines with the camshaft located in the block use pushrods to transfer motion from the lifter to the rocker arms. The rocker arm is a pivoting lever used to transfer the motion of the pushrod to the valve stem.

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Camshafts and Valvetrains

■

It changes the direction of the camshaft lift and spring closing forces, and it provides a leverage during valve opening. OHC or DOHC engines have the camshafts mounted on the cylinder heads. The camshaft lobes may contact the rocker arms directly, and a lash adjuster may be positioned under one end of the rocker arm.

■

■

215

There are two basic functions of the valve spring: First, it closes the valve against its seat; second, it maintains tension in the valvetrain when the valve is open to prevent float. To accomplish its functions, the valve spring can be designed with different characteristics and features. The most common designs include dual springs, dampers, and variable-rate springs.

REVIEW QUESTIONS Short-Answer Essays 1. What is the function of the valvetrain? 2. Explain the purpose and function of the camshaft. 3. Describe the relationship among the camshaft lobe design and lift, duration, and overlap. 4. Explain the purpose of the lifters. 5. List and explain the common methods of mounting the rocker arms. 6. List the three types of valve springs.

6. OHV engines with the camshaft located in the block use _______________ to transfer motion from the lifter to the rocker arms. 7. The design of the rocker arm is such that the side to the valve stem is usually _______________ than the side to the pushrod. 8. When the valve is opened 50 percent of its travel, the rocker arm-to-stem contact should be _______________ on the valve stem. 9. Valve springs can have a _______________ to reduce valve spring temperatures.

7. What is meant by the term duration as it relates to the camshaft?

10. _______________ lock the valve spring retainer on top of the valve spring.

8. If the rocker arm ratio is 1.5:1 and the cam lobe lift is 0.335 in. what is the actual valve opening?

Multiple Choice

9. What is the purpose of a valve rotator? 10. Explain why some camshafts have tapered lobes.

Fill-in-the-Blanks 1. The camshaft is used to control valve _______________, the _______________of opening and closing, and how long the valve will be open. 2. The _______________ of the lobe determines the amount of valve lift or opening. 3. _______________ is the length of time, expressed in degrees of crankshaft rotation, the valve is open. 4. The camshaft lobes generally have a very slight taper. This taper, along with the _______________ of the lifter and the lobe, provides for lifter rotation. 5. Lifters are mechanical or hydraulic connections between the _______________ and the valves.

1. Each of the following is part of a typical valvetrain except: C. Ports A. Lifters B. Pushrods D. Rocker arms 2. Camshaft _______________ is how long the valve stays open. A. Lift C. Ramp B. Lobe center D. Duration 3. The lobe separation angle defines. A. The height of the lobe. B. The lift of the lobe. C. The amount of overlap. D. The valvetrain clearance. 4. Technician A says that overlap improves volumetric efficiency at higher rpm. Technician B says that overlap reduces HC emissions. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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5. Hydraulic lifters can _______________at higher rpm causing _______________. A. Collapse, clatter B. Pump-up, valve float C. Leakdown, low power D. Lose oil pressure, reduced valve lift 6. Mechanical lifters require. A. a specified clearance. B. periodic adjustment. C. Both A and B D. Neither A nor B 7. A rocker arm is 0.45 in. (11.43 mm) from the pushrod to the pivot and 0.66 in. (16.76 mm) from the pivot to the valve tip. The camshaft lift is 0.36 in. (9.14 mm). How far will the valve open? A. 0.25 in. (6.35 mm) B. 0.81 in. (20.57 mm) C. 0.36 in. (9.14 mm) D. 0.53 in. (13.46 mm)

8. Which valve spring runs coolest? A. A coated spring B. A variable-rate spring C. A double-coil spring D. A quenched-coil spring 9. Technician A says that a weak spring can cause valve float. Technician B says that a weak valve spring can cause the valve to burn. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that advanced camshaft timing will increase power at high rpm. Technician B says that retarded camshaft timing will increase power at low rpm. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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CHAPTER 11

TIMING MECHANISMS

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■ ■

The function of the valve timing system. The operation of a timing chain system. The function and advantages of a timing belt system. The uses of a gear-driven timing system. The difference between an interference engine and a freewheeling engine.

■ ■ ■

The advantages of variable valve timing systems. The operation of a variable valve timing and lift system. The basic operation of displacement-on-demand.

Terms To Know Atkinson-cycle engine Cam-phasing Cam-shifting Distributor

Interference engine Solenoid Timing chain guide Timing chain tensioner

Valve timing mechanism Variable cylinder displacement Variable valve timing (VVT) system

INTRODUCTION The front end of the engine consists of the valve timing mechanism. This is either a belt(s), a chain(s), or gears used to time the rotation of the camshaft to the crankshaft. Some older gasoline and diesel engines used gear sets to keep valve timing; modern engines typically use either chains (Figure 11-1) or belts (Figure 11-2) to drive the camshaft(s). Perfect valve timing is essential for proper engine performance. Good volumetric efficiency of the engine depends on valves opening and closing at the correct time. The timing mechanism may also drive other auxiliary shafts, balance shafts, and components (such as the water pump). This chapter will expose you to the various design configurations commonly used. We will also discuss the purposes, advantages, and disadvantages of the traditional and variable valve timing and lift designs.

The valve timing mechanism drives the camshaft in the correct timing with the crankshaft. It may use a belt, chain, or gears.

VALVE TIMING SYSTEMS The timing mechanism is responsible for maintaining a perfect relationship between the rotation of the crankshaft and the camshaft, to open the valves at the right time. The intake valve must begin to open prior to the piston completing the exhaust stroke (Figure 11-3). Also, the valve must be closed at the proper time to prevent loss of compression. If the exhaust valve is not opened and closed at the precise time, the engine will not be able to breathe properly and draw in a fresh air-fuel charge. Valve timing is a function of the camshaft, which is driven off the crankshaft. The camshaft rotates at half the speed of the crankshaft to allow the valves to open only for the desired length of time. To complete one full engine cycle, the camshaft will rotate once Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 11 Secondary timing chain tensioner

Camshaft sprocket

Camshaft gear Secondary timing chain tensioner

Crankshaft gear

Timing marks

Primary chain tensioner

Timing marks

A

B

OHV engine with gear-driven camshaft

OHV engine with timing chain and gears

Chain guide

Crankshaft sprocket Timing mark

C

OHV engine with timing chain and gears

Figure 11-1 Some timing mechanisms use chains or gears. Camshaft timing marks 1/2 notch location

Top dead center

21

15 Exhaust valve closes

Intake valve opens 90 Timing belt

Exhaust valve opens

Crankshaft Crankshaft at TDC 51 OHV engine with multiple belt-driven camshafts

Figure 11-2 Many overhead camshaft engines use timing belts.

57 Bottom dead center

Figure 11-3 Valve opening is timed precisely by the camshaft through the valve timing mechanism.

and the crankshaft will complete two revolutions. The camshaft sprockets will be twice the size of the crankshaft sprockets unless an intermediate shaft is used. The valve timing system must provide perfect correlation between the camshaft and crankshaft. If the cam timing is off by one tooth, the engine will likely run very poorly; emissions will increase, and power and fuel economy will decrease. Variable valve timing and lift systems must also start with the correct alignment between the crank and the cam to allow proper variations on valve timing. Some of these systems sometimes use a secondary timing chain that can allow for changes in a camshaft’s timing (Figure 11-4). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Intake camshaft sprocket

Secondary timing chain

Exhaust camshaft sprocket

Figure 11-4 A secondary chain may be used for a camshaft, particularly when the engine uses variable valve timing.

The engine may be a free-wheeling or interference type. A free-wheeling or noninterference engine means that when the timing mechanism fails, the valves will usually not hit the pistons. Even some free-wheeling engines can allow the valves to contact the pistons if the engine rpm is high enough when the mechanism breaks. On an interference engine, it is very likely that when the timing mechanism breaks, the valves will contact the pistons (Figure 11-5). At best, valves will need to be replaced. At worst, valves will float at their maximum lift and then be driven into the pistons and the whole engine will need to be overhauled or replaced. Many timing belts require replacement at regular maintenance intervals. Timing gears and chains are generally replaced during an engine overhaul or when they begin to make noise or show signs of wear. When a timing mechanism breaks, engine damage can be severe. You can help your customers by explaining the importance of proper timing system maintenance, including routine timing belt replacement. Every valve timing system will have alignment marks on the sprockets or gears to make sure you can properly time the engine (Figure 11-6). Camshaft or valve timing is usually established with cylinder number 1 at TDC on the compression stroke.

In an interference engine, the valves hit the top of the pistons when they are open and the piston is at TDC. This can occur when the timing mechanism breaks.

Timing marks

Figure 11-5 Every valve that came out of this engine was bent after the timing belt snapped.

Figure 11-6 Timing marks on the sprockets allow proper alignment during service.

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CHAIN-DRIVEN SYSTEMS

A timing chain guide is a length of metal with a soft face to hold the chain in position as it rotates. A timing chain tensioner maintains tension on the chain or belt to prevent slapping or skipping a tooth.

Shop Manual Chapter 11, page 496

Chain-driven systems can be used either on cam-in-the-block or on overhead-cam engines. The timing chain is a strong, long-lasting way of linking the cam to the crank. A flat-link silent chain makes much less noise than a roller-style chain. The chain system is still noisy, however, which is objectionable to some consumers. It is also more expensive for the manufacturers to fit a chain rather than a belt. When a chain is used, steel, fiber composite, or composite plastic sprockets may be used to rotate with the chain. To drive an overhead camshaft(s), one or more timing chain guides and a timing chain tensioner must be used. The guides hold the chain against a synthetic rubber, nylon, or Teflon face. The timing chain tensioner holds proper tension on the guide to take up slack as the chain and guides wear. The tensioner is usually a spring-loaded plunger that may be fed with oil pressure to take up chain slack. The tensioner also has a spring-loaded ratcheting system. When the chain or guide is worn enough, the spring will push the plunger out one more step on the ratchet. This also prevents excessive noise at start-up, before oil pressure is held behind the plunger (Figure 11-7). Timing chains receive splash oiling often with a slinger placed at an oil passage. Tensioners are items that wear out with time. A tensioner is usually replaced when a timing belt or chain is replaced on regular service intervals. Engines that use balance shafts may use two chains: one will drive the camshafts and the other will drive the balance shaft (Figure 11-8). Note the guides and tensioners as well. This engine has dual balance shafts. You can see that they will spin at twice the speed of the crankshaft, which is typical of balance shafts. You can see this by comparing the size of the balance shaft sprockets to that of the crankshaft sprocket. Chains are generally replaced during an engine overhaul or if they begin to make excessive noise. As they wear, you can often hear the chain slap during a quick deceleration. Primary chain

Balance shaft chain

Figure 11-7 The timing chain tensioner uses spring pressure and oil pressure to maintain the correct tension on the chain.

Tensioner

Guide

Figure 11-8 This DOHC engine shows the tensioner, guides, and primary and balance shaft chains. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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221

AUTHOR’S NOTE I heard the telltale rattle of my timing chain hitting the cover during deceleration for several weeks before I took a Saturday and replaced the timing chain, guides, sprockets, and tensioner. My chain and sprockets were very worn; I was lucky they didn’t cause me to walk home one day.

BELT-DRIVEN SYSTEMS A timing belt is frequently used on overhead camshaft engines. The timing belt is strong and very quiet. It is much more cost-effective for the manufacturer than gears or chains. As belt materials have improved, belt replacement intervals have increased. This is good for the consumer because timing belt replacement can be a costly maintenance item. Some manufacturers do not even specify a replacement interval; they simply require the technician to inspect the belt periodically. The timing belt runs from the crank sprocket to the cam sprocket(s) without a guide. Instead, an idler pulley is used to guide the belt and provide a tension adjustment. Most newer timing belt systems use an automatic tensioner that self-adjusts; others require periodic adjustment (Figure 11-9). These tensioners used with timing belt systems have chambers on both sides of a piston that is filled with silicone oil. They are not fed oil externally. If belt tension increases, the piston moves downward. The piston movement causes an increase in hydraulic pressure in the lower chamber. Since the check ball is closed, the oil must seep past the piston and cylinder wall to go into the reservoir chamber. As oil seeps into the reservoir, the tension piston moves slowly down the cylinder until the load from the belt balances with spring tension (Figure 11-10). Alternately, when the belt tension is increased, spring tension forces the piston to move up in the cylinder and take up the slack. The timing belt may also drive other components. On older engines, it frequently drove the auxiliary shaft that turned the distributor (Figure 11-11). Other manufacturers use the timing belt to drive the water pump. When servicing or replacing

Belt tension

Overhead camshaft sprocket timing mark

Oil seal

Automatic tensioner

The distributor is usually driven by the camshaft. It uses the timing of the valves to control the timing of the spark ignition.

Arrow on rear cover

Diaphragm

Piston Reservoir chamber Oil

Check ball

Cog belt Cylinder Spring

TDC mark

Crankshaft sprocket

Figure 11-9 An automatic adjusting tensioner may be used to maintain proper belt tension.

Pressure chamber

Figure 11-10 Hydraulic pressure flows through the tensioner when belt tension increases.

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Chapter 11 Cam gears Coolant pump

Camshaft sprocket

Timing belt tensioner

Crankshaft gear

Figure 11-12 This DOHC timing belt drives all four camshafts.

Belt tensioner pulley

Crankshaft

Distributor drive shaft

Figure 11-11 A timing belt may also be used to drive the distributor shaft.

the timing belt, it is recommended that the water pump be replaced at the same time. This type of setup makes water pump removal easier when the timing belt and other components are already removed. You will certainly be saving the customer a headache and money by taking care of it now. In some dual overhead camshaft (DOHC) V6 engines, a single timing belt may be used to drive the four camshafts and idler pulleys (Figure 11-12). In other DOHC V6 engines, a timing chain surrounds the crankshaft sprocket and intermediate shaft sprocket and the chain drives the intermediate shaft sprocket. A front cover is mounted over the chain drive, and an outer sprocket is mounted on the intermediate shaft on the outside of the front cover. This allows for replacement of the belt without disassembling the front chain cover. A timing belt surrounds the outer intermediate shaft sprocket to drive the overhead camshafts on both sides of the engine. The back side of the belt contacts two idler pulleys and a tensioner pulley (Figure 11-13). A timing belt may also be used on engines with a balance shaft(s). Not to be confused with a “wet-belt,” a standard timing belt does not need lubrication; in fact, one reason for premature failure is oil or coolant leaking onto the belt. From 2007 to 2011, Ford of Europe used “wet-belts” in place of timing chains on some DLD series engines. The advantage to the wet-belt system is reduced timing mechanism friction, bringing about an increase in fuel economy while lowering emissions with quieter operation. However, due to cases of early failure, it is not an uncommon practice for service technicians to replace the wet-belt and its components with the older timing chain kit (cartridge) at the 125,000-mile or 10-year replacement interval.

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Timing Mechanisms

Belt enlargement

Intermediate shaft belt sprocket

Timing chain

Crankshaft pulley

Figure 11-13 A DOHC engine that uses a timing chain to drive an intermediate shaft. A belt off the intermediate shaft sprocket drives the camshafts.

GEAR-DRIVEN SYSTEMS Gear-driven systems are not as popular as they used to be, in part because they are used only on camshaft-in-the-block engines (Figure 11-14). They are a very reliable and precise system, although a little noisy. Because there is no chain or belt slack, valve timing is always very close to perfect. The gears are very durable, as long as they receive adequate lubrication. Many diesel engines use timing gears because the valve timing is very critical and it adds to the idea of the long-lasting engine (Figure 11-15).

A BIT OF HISTORY Chrysler’s first V-style engine was its legendary 331 c.i.d. “Hemi,” introduced in 1951. It had a compression ratio of 7.5:1, with an overhead valve configuration. It put out 180 hp. Though today’s new “Hemi” engine is slightly larger, at 348 c.i.d., it puts out 340 hp.

Camshaft gear

Timing marks

Crankshaft gear

Figure 11-14 The crankshaft gear drives the camshaft directly when gears are used. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 11-15 This 7.3-liter diesel engine uses timing gears.

VARIABLE VALVE TIMING SYSTEMS

A variable valve timing (VVT) system refers to an engine that uses an adjustable valve train to vary the amount and timing of an air-fuel mixture entering or leaving a cylinder.

In years past, manufacturers were able to design a camshaft profile that gave the engine certain horsepower and torque characteristics at specific engine speeds. One of the most significant changes to engine technology in recent years has been the ability to vary the valvetrain geometry during engine operation. The term variable valve timing (VVT) system is used to describe a vast array of different valvetrain changing type systems. These systems have added components that allow the intake or exhaust valves (or both) to change the lift, duration, or timing during engine operation.

Variable Valve Timing (Cam-Phasing) Variable valve timing systems have either mechanical, hydraulic, or electrical controls, or even a combination. Most modern engines use electrical components to control or monitor the VVT system. The timing of the valves is a critical component of the engine’s operation. Changing valve timing is called cam-phasing (Figure 11-16). Of the different VVT systems, the cam phasing exclusive systems are the most common due to being the least expensive to manufacture and the simplest in design. With a traditional valvetrain an engine may have a lot of power and run very smoothly at a higher speed but then run very rough and have low horsepower at idle. In an ideal situation, at low engine speeds, the engine should have a lot of torque, good efficiency, and low emissions. At high speeds, the engine should have more power. At high engine speeds, the engine requires more air to produce more power. A camphasing system can retard the valve timing at higher rpms to keep the valves open later in the stroke. This is because the stroke is occurring so quickly and it still takes significant time to get the stream of air into the cylinder. Cam-phasing systems can also lower the cold-start emissions and overall emissions of a vehicle. By reducing valve overlap at idle, hydrocarbon emissions are reduced. Less of the fresh air charge is allowed out the exhaust port. By increasing the period of overlap at higher rpm, the engine can breathe better. In some systems, during cruise conditions the exhaust valves are held open longer. This allows some exhaust gases to be held in the combustion chamber to mix with the incoming intake charge. By adding some inert gases to the charge, the heat of combustion is reduced and oxides of nitrogen (NOx) emissions

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Timing Mechanisms

Figure 11-16 Cam phasers change valve timing.

are decreased. The exhaust gas recirculation (EGR) valves used on many vehicles perform this same function. They actually add exhaust gases into the intake charge to dilute the mixture and reduce combustion temperatures. The EGR valves and their systems in general have had many problems over the years. The function of the variable valve timing used on Ford’s 2.0-liter Zetec engine has allowed Ford to eliminate the EGR system and still meet the NOx standards. This type of technology allows manufacturers to use smaller displacement engines. Most manufacturers are now using VVT systems in many engine designs to get better fuel economy, lower emissions, and more performance. A few examples of these designs include Audi’s AVL, BMW’s Valvetronic, Chrysler’s VVT, Ford’s VCT, GM’s DCVCP, Honda’s VTEC, Hyundai, Kia, and Mitsubishi’s CVVT, Mazda’s SVT, Mercedes Camtronic, Nissan’s VCT, Porsche’s VarioCam, Subaru’s AVCS, and Toyota’s VVT.

GM VVT GM’s VVT system improves engine performance, fuel economy, and emissions by changing valve timing only. It also eliminates the need for an EGR and AIR systems. On some applications, it allows 90 percent of the engine’s torque to be available between the wide range of 1,900 rpm and 5,600 rpm. The VVT system uses a camshaft position actuator for each of the intake and exhaust camshafts that bolt onto the end of the camshafts. The actuators lock the exhaust cam in its fully advanced position and the intake cam in its fully retarded position for start-up and idle. This minimizes overlap to create a very smooth idle. Off idle, the powertrain control module (PCM) controls the camshaft actuator solenoid valves to allow the position actuators to alter intake and exhaust timing by 25 camshaft degrees. The PCM looks at information about engine coolant temperature, engine oil temperature, intake airflow, throttle position, vehicle speed, and volumetric efficiency to determine the optimum positioning of the camshafts for any given set of conditions. The solenoid valve controls oil pressure to the position actuator to effect changes in camshaft timing. The camshaft position actuator has an outer housing that is driven by a timing chain. A rotor with fixed vanes lies inside the assembly and is attached to the camshaft. The solenoid valve, as commanded by the PCM, controls the direction and pressure of oil flow against the vanes. Increasing pressure against one side of the vanes will advance the camshaft variably until the desired position is achieved. Changing the oil pressure to the opposite side of the vanes will retard the camshaft. Whenever the engine is off idle, the PCM is continuously providing electrical pulses to the solenoid valves to modify camshaft timing or to hold it in the desired position. Under light engine loads, the PCM retards the valve timing to reduce overlap and maintain stable engine operation. When the engine is under a medium load, overlap is increased to improve fuel economy and emissions. To improve mid-range torque under a heavy load and at moderate or low rpm, intake valve timing is advanced. Under a heavy load at high rpm, intake valve closing is retarded to improve engine output (Figure 11-17). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Intake camshaft sprocket

Drain Piston

Straight splines inside sprocket

Oil passage

Drive sprocket Intake camshaft

Piston

Helical spline on camshaft

Exhaust camshaft sprocket

Chain from crankshaft

Helical spline

Figure 11-17 This cam-phasing actuator rotates the camshaft in relation to the crankshaft.

VARIABLE VALVE LIFT (Cam-Shifting) Systems that can change valve lift are known as cam-shifting (sometimes called camswitching) systems. Changes in valve lift can be used to increase power at high rpm, to vary engine displacement, or to control engine speed, thus allowing the removal of the throttle plate for increased intake airflow. Manufacturers accomplish this in different ways. One way is by using camshafts with additional lobes of different height that can switch back and forth during engine rpm and load changes. Changes in valve lift can also be achieved by changing the range of rocker arm or pushrod movement. This is done using hydraulic pressure or by an electrically operated actuator.

VARIABLE VALVE TIMING AND LIFT SYSTEMS Anxious to reduce the limitations caused by compromises in camshaft design, many manufacturers are combining variable valve timing and variable valve lift systems. Used together, these technologies reduce inherent compromises. The systems may be designed to improve fuel economy and performance while reducing emissions. For example, increasing valve lift and retarding valve timing can increase the output of an engine significantly at higher rpm when volumetric efficiency normally decreases. This is when the engine torque traditionally falls off due to the inability to fill the chambers. There are many variations in system design. More and more manufacturers are adding variable valve timing and/or valve lift systems to their vehicles every year. Honda has been using a variable timing and lift system since 1989.

Honda VTEC Honda’s popular variable timing and lift electronic control (VTEC) system modifies both valve timing and valve lift. Honda took the lead in production variable valve timing with its VTEC system, designed to improve performance at higher rpm. It increased the engine output over a single cam non-VTEC engine by 25 percent. In the VTEC system, each pair Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanisms Cam lobe

1

2

3

To camshaft lobes Actuator pin

Rocker arms To valves

#1 + #3 rocker arms act on low-speed lobes #2 rocker arm acts on high-speed lobe Signal from PCM

Oil control valve for camshaft actuator

Oil PSI

Figure 11-18 When a predetermined rpm and other conditions are met, the PCM signals the cam actuating control valve. This valve allows oil pressure to push a pin through the rocker arms, activating the high-speed rocker arm and cam lobe.

of valves has three cam lobes and three rocker arms. During low-speed operation, the low-speed rockers push directly on the two regular-speed lobes. At high rpm, when the PCM determines that the third lobe will improve performance, it signals an oil control valve to engage the third rocker to the high-speed lobe. A pin slides out of the low-speed rockers and into the high-speed rocker to engage it to use the camshaft lobe with more aggressive timing, lift, and duration. On one Acura model, the high-speed lobe has an advertised duration of 290 degrees; that is a race-quality camshaft. Figure 11-18 shows a simplified diagram of the pin actuating system. Honda’s i-VTEC was introduced in 2001 and uses a more powerful PCM to control the camshaft. This system uses an adjustable oil-driven cam gear (also called a cam-phasing actuator) that actually closes the intake valve well into the compression stroke when the PCM determines that it should be in “economy mode.” This action is similar to what happens in the Atkinson-cycle engine. Later, Honda introduced the Advanced VTEC, which uses an even faster PCM. The intake valves have less lift at low engine speeds, which gives the engine an estimated 13 percent increase in fuel economy and a reduction in emissions.

Toyota VVT Toyota is using a VVT system that changes the phase angle of the intake camshaft relative to the crankshaft to advance or retard the camshaft. A hydraulic actuator (called a variator), controlled by the PCM sits on the end of the camshaft to effect timing changes. The camshaft timing can be varied continuously up to 60 degrees. The system also employs a variable lift and duration system by using two different camshaft lobes for each set of valves. One rocker arm opens both intake valves. During low- to moderate-speed operation, the “high-speed” cam lobes do not contact the rocker arms. At higher speeds, a sliding pin is pushed by hydraulic pressure to take up the space between the higher-duration Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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cam lobes. The increased rocker arm movement also increases valve lift. When the system is off, the variator defaults to the retarded position. The VVT-I system operates similarly to VVT but adds greater control of valve duration through camshaft rotation.

Dual VVT-i (Dual Variable Valve Timing with Intelligence) Dual VVT-I is the most commonly used variable valve timing and lift system used by Toyota today. The Dual VVT-I system operates similarly to VVT-i but includes control of the exhaust camshaft. The advantages to this are lower emissions through faster catalytic converter warm-up and increasing internal exhaust gas recirculation (internal EGR), better startability, increased fuel economy and performance, and smoother-running at lower rpms.

Fiat’s MultiAir Fiat uses hydraulic oil pressure controlled by a normally closed, electrically operated solenoid (Figure 11-19). The solenoid is located in between the camshaft and the intake valves. When the solenoid is de-energized, the oil inside it causes it to act as a solid lifter. As the solenoid is energized, it prevents the intake valve from opening due to the oil being bled off. When desired, the MultiAir system has the ability to open the valves only part way.

Variable Cylinder Displacement Variable cylinder displacement systems allow the engine under certain conditions to operate on fewer cylinders than it is equipped with, mainly to increase fuel economy.

Many manufacturers are now making engines that, when conditions permit, can “cancel” multiple cylinders to provide better fuel economy. These variable cylinder displacement systems are known as displacement-on-demand, variable displacement, variable cylinder management, or active fuel management engines. These systems are currently in some GM Active Fuel Management System (AFM), known previously as displacement-ondemand (DOD), Honda Variable Cylinder Management System (VCM), and Chrysler Multi Displacement System (MDS) vehicles.

GM’s Active Fuel Management System The AFM system is designed to improve fuel economy. This type of system is not new technology and has been tried by many manufacturers; it is a new configuration of an older system that did not work well. The 181 Cadillac 8-6-4 used a similar system to deactivate cylinders for fuel economy. Unfortunately, the car never succeeded with consumers because the technology was too far ahead of its time. Semiconductors in vehicles were still in their infant stage, and there were many consumer complaints of engines stalling and

Flat’s MultiAir variable valve-lift system

Figure 11-19 Using an electronically controlled solenoid valve, lift and duration can be controlled. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanisms

rough running when the computer automatically turned cylinders off. Modern computer speed and complexity make the new versions of displacement-on-demand barely noticeable to the consumer. The system allows for maximum power when the consumer demands acceleration and a “smaller” engine when the driver is cruising. The engines use special hydraulic valve lifters to stop valve opening to selected cylinders during cruising and deceleration. The PCM activates a solenoid that allows oil pressure to unlock a pin in the valve lifter. Then rather than opening the valve, it collapses as the camshaft tries to push it up. The PCM also stops delivering fuel to the four cylinders during cylinder deactivation. Drivers say the transition is seamless; they do not even feel when the engine changes from four to eight or back again. Manufacturers claim up to 25 percent fuel economy increases. One V8 engine tested achieved 30 miles per gallon during highway driving. The lifter used in an engine with an active fuel management system (also called DOD) is slightly different (Figure 11-20). When the vehicle is cruising down the highway, it does not require a lot of horsepower. A larger V8 engine can be reduced to generating power from only four of the cylinders; this is called cylinder deactivation. There are many examples from many manufacturers on how variable displacement works, but many of them use a method of controlling the oil flow in and out of the lifter. This, in turn, controls the action of the lifter and the opening of the valves. This is part of a strategy that the computer uses to deactivate a cylinder. Cylinder deactivation components that are common on a V8 engine include a valve lifter oil manifold assembly that is mounted just below the intake manifold and above the cylinder block, oil control solenoids mounted in the manifold assembly, and an oil pressure relief valve that is located in the oil pan. When requested by the engine computer, one or many of the solenoids will be energized. When a solenoid is energized it opens a pathway, thus allowing pressurized oil to flow to the lifter bores through a separate vertical passage. There are two passages per cylinder: one for intake and one for exhaust valves. A bleed passage leads excess oil pressure straight to the oil sump (Figure 11-21). The lifter of a cylinder deactivation engine has a small pin inside the center. The lifter has many small parts, but the lifter itself is separated into two main areas: the outside of the lifter and the pin housing (inner part of the lifter where the pushrod sits). When the

229

A solenoid is an electromechanical device. It is typically operated by the PCM through an electrical signal and mechanically controls flow of air, oil, fuel, or other substances. A fuel injector is a type of solenoid.

Figure 11-20 These are the parts of a variable displacement (active fuel management) valve lifter. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 11-21 This is the variable displacement (active fuel management) valve lifter system.

solenoid is activated, pressurized oil pushes a lock pin in the pin housing. This locks the lifter in the valve closed position. The outside of the lifter body continues to move with the camshaft. The pin housing and the lifter body are now independent of each other, in terms of movement. This allows the pressure from the valve spring to force the pushrod down into the bore of the lifter and follow the contour of the camshaft, thus keeping the valve closed. This is similar to what happens when a valve lifter in a normal engine completely collapses and cannot hold its own pressure. When cylinder deactivation is not needed, the solenoid is electronically deactivated by the computer, and oil flow to the lifter is no longer pressurized. This causes the pin to release and lock to the outer housing, because of a spring, and the inner pin housing and the outer part of the lifter now move as one component. This allows the pushrod to move and thus the valve to open and close with the movement of the camshaft. When working with any engine, it is important to refer to technical service bulletins (TSBs) when there is a problem. One common complaint and TSB related to these types of lifters is related to the engine oil. If the engine oil is not maintained properly or the incorrect viscosity of oil is used problems with the lifter pin locking and unlocking can result, causing the check engine light and a diagnostic trouble code to appear;. There is also a small oil filter inside the manifold assembly that requires periodic maintenance. Having dirty oil, aerated oil, low oil level, incorrect oil viscosity, or worn lifters can sometimes cause lifter noise upon start-up. The number and types of systems in use increases each year; the idea has proven to be effective in improving power and in lowering emissions. Designs in the works include valves opened by electrically operated solenoids. This system would offer infinitely variable valve lift, duration, and timing.

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SUMMARY ■

■ ■ ■

■

■ ■

The front end of the engine consists of the valve timing mechanism. Proper valve timing is essential for proper engine performance. Valve timing systems may use a belt, chain, or gears to link the camshaft to the crankshaft. Marks are provided on the sprockets, gears, covers, block, or head to properly time the engine, usually at TDC firing cylinder number 1. A timing chain is a long-lasting drive mechanism that can be used on cam-in-the-block or overheadcam engines. Timing chains are not generally replaced as a regular maintenance service. Dual timing chains may be used to drive camshafts individually on variable valve timing engines or on engines with balance shafts.

■ ■ ■ ■ ■

■

Timing belts are a very popular and cost-effective way to drive overhead camshafts. Timing belts usually require periodic replacement as a maintenance service. Timing gears are sometimes used in heavy-duty diesel engines. Timing gears are very durable and provide precise control of timing. Manufacturers are increasingly using variable valve timing and/or lift systems to overcome the limitations of the compromise of one camshaft for all engine speeds and loads. Many manufacturers are now making variable cylinder displacement engines that can “cancel” multiple cylinders to provide better fuel economy.

REVIEW QUESTIONS Short-Answer Essays 1. Explain the purpose of precision valve timing. 2. List the types of timing mechanisms. 3. Why do modern passenger car engine designs tend to use timing belts or chains rather than gears? 4. Describe the difference between a free-wheeling and an interference engine. 5. Explain the maintenance requirements of the different styles of timing mechanisms. 6. Describe the operation of a timing chain tensioner. 7. Explain the advantages of variable valve timing. 8. Briefly explain the operation of Honda’s VTEC system. 9. Describe how a variable displacement (or displacement-on-demand) lifter works to deactivate a cylinder. 10. Briefly explain the operation of Fiat’s MultiAir system.

Fill-in-the-Blanks 1. Valve timing is a function of the _______________. 2. The camshaft rotates _______________ as fast as the crankshaft.

3. Proper valve timing is established with cylinder number 1 at _______________ of the _______________ stroke. 4. Timing _______________mechanisms may be used on OHV or OHC engines. 5. The timing chain _______________ holds the chain in proper alignment. 6. The _______________ takes up slack on a timing chain. 7. Balance shafts spin at _______________ the speed of the crankshaft. 8. A worn timing chain will make the most noise during engine start-up and _______________. 9. By reducing the amount of overlap at idle, a VVT system can reduce _______________ emissions. 10. Some VVT systems eliminate the need for the _______________ emissions control system.

Multiple Choice 1. Valve timing affects each of the following except: A. Engine torque C. Emissions B. Spark timing D. Fuel economy

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2. Each of the following is a typical type of valve timing mechanism except: A. Chain C. Gear B. Belt D. Band 3. Technician A says that timing belts are quieter than timing chains. Technician B says that timing chains generally last longer than timing belts. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. An automatic timing belt tensioner: A. receives oil under pressure to tension the belt. B. has triple-coil springs to ensure proper tension. C. should be adjusted every 60,000 miles. D. is filled with silicone oil. 5. Which engines use an auxiliary shaft chain and a timing belt driven off of the auxiliary shaft sprocket? A. Eight-cylinder OHV engine B. Four-cylinder DOHC engine C. V6 DOHC engine D. Diesel engines 6. The quietest timing mechanism is the. A. belt. C. band. B. chain. D. gears.

7. A VVT system may be able to eliminate the system: A. Spark timing B. Positive crankcase ventilation C. Exhaust gas recirculation D. Valvetrain 8. The Honda VTEC system: A. modifies valve lift. B. changes valve timing. C. changes valve duration. D. All of the above. 9. Reducing valve overlap at idle reduces: A. hydrocarbon emissions. B. oxides of nitrogen emissions. C. carbon monoxide emissions. D. All of the above. 10. Technician A says that a VVT system may increase the overlap at higher rpm. Technician B says that a VVT system may retard the intake timing under heavy-load, high-rpm conditions to improve power. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

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CHAPTER 12

ENGINE BLOCK CONSTRUCTION

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■ ■

The purpose of the cylinder block. The construction and components of the cylinder block. The purpose and machining processes of the cylinder bore. The purpose and machining process of the main bore. Short block, long block, and crate engine and their uses.

■ ■ ■ ■ ■ ■

The components of the crankshaft. The relationship of crankshaft throw to stroke and firing impulses. The forces applied to the crankshaft. The manufacturing processes and materials used in crankshaft design. The purpose of the harmonic balancer. The purpose of the flywheel.

Terms To Know Bearing inserts Bedplate Connecting rod–bearing journals Core plugs Crankshaft counterweights Crankshaft throw

Cylinder block Harmonic balancer Honing Long block Main-bearing journals Main bore

Main caps Oil galleries Short block Splayed crankshaft Torque converter Torsional vibration

INTRODUCTION The cylinder block and the components within it make up the bottom end of the engine. This is also called a short block. A long block is essentially a short block with cylinder head installed (Figure 12-1). Most crate engines can be ordered as short or long blocks. Engine materials and machining have changed significantly in the past 20 years. Clearances have decreased, ring and piston choices abound, and block reconditioning is often limited. A silicone-impregnated, cast aluminum alloy block with integral bores cannot be refinished, for example. The function and purpose of the flywheel and harmonic balancer are also covered in this chapter because these components affect the function of the block assembly. You must have access to thorough service information to properly service a modern engine (Figure 12-2). The service information will provide you with what you need to know about the materials used for the block, machining processes allowed for repairs, and proper repair procedures.

A short block is a block assembly without the cylinder heads and some other components.

A long block is an engine block with the cylinder head(s) and other components mounted.

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Figure 12-1 This is a short block with a cutaway cylinder head unit.

AUTHOR’S NOTE You may be able to improve the performance and durability of an older engine by using newly designed replacement parts with improved engineering, materials, and machining.

GENERAL MOTORS ENGINES 3.0L, 3.8L, and 3.8L "3800" V6 (Continued) Engine Specifications (Continued) Crankshaft Main and Connecting Rod Bearings Connecting Rod Bearings

Main Bearings Engine All Models 1

Crankshaft Clearance Journal Diam. Clearance Thrust End Play Journal Diam. In. (mm) In. (mm) Bearing In. (mm) In. (mm) In. (mm) 1 1 .0003–.0018 2.4988–2.4998 .003–.009 2.2457–2.2499 .0003–.0028 2 (63.469–63.494) (.008–.005) (.08–.23) (57.117–57.147) (.008–.071)

Side Play In. (mm) .003–.015 (.076–.38)

Maximum taper is .0003 in. (.008 mm).

Pistons, Pins, and Rings Pins

Pistons Engine

All Models

Rings

Clearance In. (mm)

Piston Fit In. (mm)

Rod Fit In. (mm)

Ring No.

1.0013–.0035 (.033–.089)

.0004–.0007 (.010–.018)

.00075–.00125 (.019–.032)

1 2 3

1

End Gap In. (mm) .010–.020 (.254–.508) .010–.020 (.254–.508) .015–.035 (.381–.889)

Side Clearance In. (mm) .003–.005 (.08–.13) .003–.005 (.08–.13) .0035 (.09)

Measured at bottom of piston skirt. Clearance for 3.8L turbo is .001–.003 in. (.03–.08 mm).

Figure 12-2 This service information includes critical measurement and torque specifications. You cannot service an engine properly without an engine’s specific information.

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Engine Block Construction Valve Springs Free Length In. (mm)

Engine 3.8L (VIN C)

2.03 51.6

3.0L & 3.8L (VIN 3)

2.03 51.6 2.03 (51.6)

3.8L (VIN 7)

Pressure Lbs. @ In. (Kg @ mm)

Valve Closed 100–[email protected] (45–49@44) 85–[email protected] (39–42@44) 74–82@173 (33–37@44)

Valve Open 214–[email protected] (97–61@33) 175–[email protected] (79.1–[email protected]) 175–[email protected] (79.1–[email protected])

Camshaft Engine 3.0L

Journal Diam. Clearance In. (mm) In. (mm)

Lobe Lift In. (mm)

1.785–1.786 .0005–.0025 Int. .210 (45.34–45.36) (.013–.064) (5.334)

Exh. .240 (6.096)

.0005–.0025 3.8L 1.785–1.786 (VIN C) (45.34–45.36) (.013–.064) 3.8L 1.785–1.786 .0005–.0025 (VIN 3) (45.34–45.36) (.013–.064) 3.8L 1.785–1.786 .0005–.0025 (VIN 7) (45.34–45.36) (.013–.064) 1

1 .272 (6.909) 1 .245 (6.223) ....

Specification applies to both intake and exhaust.

235

Caution: Following specifications apply only to 3.0L (VIN L) 3.8L (VIN 3), 3.8L (VIN 7) and 3.8 "3800" (VIN C) engines. TIGHTENING SPECIFICATIONS Application Camshaft Sprocket Bolts Balance Shaft Retainer Bolts Balance Shaft Gear Bolt Connecting Rod Bolts Cylinder Head Bolts Exhaust Manifold Bolts Flywheel-to-Crankshaft Bolts Front Engine Cover Bolts Harmonic Balancer Bolt Intake Manifold Bolts Main Bearing Cap Bolts Oil Pan Bolts Outlet Exhaust Elbow-to-Turbo Housing Pulley-to-Harmonic Balancer Bolts Outlet Exhaust Right Side Exhaust Manifold-to-Turbo Housing Rocker Arm Pedestal Bolts Timing Chain Damper Bolt Water Pump Bolts

Ft. Lbs. (N.m) 20 (27) 27 (37) 45 (61) 45 (61) 160 (81) 37 (50) 60 (81) 22 (30) 219 (298) 2 100 (136) 14 (19) 13 (17) 20 (27)

20 (27) 37 (51) 14 (19) 13 (18)

1Maximum torque is given. Follow specified procedure

and sequence. 2Tighten bolts to 80 in. lbs. (9 N.m).

Figure 12-2 Continued

BLOCK CONSTRUCTION The cylinder block is the foundation of the engine. It houses all the rotating and reciprocating parts of the bottom end and provides lubrication and cooling passages (Figure 12-3). The engine block is cast; hot, liquid metal is poured into a mold and allowed to cool and solidify. This forms the structure of the block. Sand is used inside the mold to provide water jackets around the bores. Holes are drilled in the outside of the block to remove the sand after casting. These holes are then sealed with core plugs. Blocks have traditionally been made of gray cast iron because of its strength and resistance to warpage. After it is cast, it is easily machined to provide rigid bores for the pistons, crankshaft, and lifters (and camshaft, if applicable). The block is also machined on the top, bottom, and ends to provide good sealing surfaces for the head, oil pan, transaxle, and timing cover (Figure 12-4). Many newer designs use a cast aluminum alloy for the block. This offers a significant weight reduction that helps manufacturers meet fuel economy standards without sacrificing performance. Cast aluminum alloy blocks are more prone to cracking and warping problems when they are overheated, however. The cylinder wall may have replaceable or cast-in-place steel liners. When they are cast in place, they are called dry liners because no coolant hits the surface directly. Replaceable liners are called wet sleeves; coolant circulates all around the sleeve. The sleeve is sealed by an O-ring on the bottom and the head gasket and head on the top. Some aluminum blocks are fitted with cast-iron cylinder heads and/or thickly cast oil pans to provide added rigidity to the block. Other newer engines are all aluminum. In some cases, a silicone-impregnated aluminum alloy is used in the casting. After the bores are machined, a special honing process removes the aluminum and uncovers a layer of hard silicone to form the thin wear wall of the bore. These cylinders cannot be bored oversize unless a sleeve is installed.

The cylinder block is the main structure of the engine. Most of the other engine components are attached to the block.

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Chapter 12

Piston and connecting rod assembly

Flywheel

Oil pickup assembly

Crankshaft

Crankshaft bearings and caps

Oil pan and gasket

Figure 12-3 Cylinder block and related components.

The bedplate is the lower part of a twopiece engine block. The bedplate is also called the main girdle.

Other aluminum blocks use a special lost-foam casting process. The foam is vaporized in the casting process. The casting molds are made in a foam pattern that allows more complex shapes. These aluminum blocks (and heads) almost look as though they are made of silver Styrofoam (Figure 12-5). The manufacturers claim increased reliability and accuracy with lower machining costs. Some manufacturers are using a two-piece block design. This design has a bedplate or a one-piece main-bearing cap (Figure 12-6). It provides a stronger lower end because it ties all of the main caps together to improve block stiffness and reduce engine vibration. This design is often called modular. “Modular” actually refers to the ability of the production plant to easily build the same design engine in different configurations (Figure 12-7).

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237

Figure 12-4 A bare V8 block.

Bedplate

Crankshaft

Block

Figure 12-5 This Saturn engine uses the lost-foam casting process.

Figure 12-6 A cylinder block with a bedplate.

Lubrication and Cooling A cylinder block contains a series of oil passages, called oil galleries, that allow oil to be pumped through the block and crankshaft to reach the main bearings, and to the camshaft and up into the cylinder head. The oil lubricates, cools, seals, and cleans engine components (Figure 12-8). Some of the heat generated by the engine must be absorbed by the block and cylinder heads. This heat is wasted power and must be removed before it damages the engine. The engine has water jackets throughout the engine to help cool the engine. The area around the cylinder bores has coolant circulating and coolant flowing into the cylinder head to cool the area around the valve seats. Coolant circulates through the block jackets and coolant passages to transfer heat away from these hot areas into the rest of the cooling system.

Oil galleries are drilled passages throughout the engine that carry oil to key areas that need lubrication.

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Chapter 12

Figure 12-7 A two-piece block and head.

Cam bearing Crank bearing Filter

Oil pickup Oil pump

Figure 12-8 Cylinder block oil system and galleries. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Block Construction

239

Honed

Plateau honed

Figure 12-9 Cylinder block core and gallery plugs.

Figure 12-10 This exaggerated view shows the rough edges of honing, which are then cut down by plateau honing. This process holds oil for the rings but causes less wear to the rings than regular honing.

Core Plugs All cast cylinder blocks use core plugs. These may also be called expansion plugs or freeze plugs. During the manufacturing process, sand cores are used. These cores are partly broken and dissolved when the hot metal is poured into the mold; however, holes must be placed in the block to get the sand out after the block is cast. The core holes are machined, and core plugs are placed into them to seal them (Figure 12-9).

Cylinder Bores The cylinder bores may be either integral or sleeved. Integral bores are machined out of the casting to fit the pistons. They are bored first and then honed to size to provide the proper surface finish for the rings. Honing a cylinder uses special stones to make small scratches on the surface. This removes the glaze on the surface. It also allows oil to sit in the small scratch lines and help seal the piston rings. Bores are plateau honed from the factory to provide good cylinder wall lubrication with minimal wear. A rough stone hone is used to provide a crosshatch pattern in the cylinder. The crosshatch scratches of 50 to 60 degrees on the cylinder wall hold oil to lubricate the pistons and rings. The cylinder is then finish honed with a soft stone to cut the rough edges off of the grooves in the cylinder wall. The result is a smooth plateau for the rings and pistons to contact (Figure 12-10). Clearances between the pistons and cylinder bores are commonly very small on modern engines, as little as 0.0005 in. the machining processes are precise. Many aluminum blocks will use cast-iron sleeves either cast or dropped into the block. The block is supported at the top and bottom during the machining processes to prevent twisting. The lower portion of the block has webbing to help keep the cylinders straight during engine operation. The cylinder head helps secure the top half of the block. The top of the block must be very smooth so that the cylinder head can seal it. The base or bottom of the block is also machined to allow for proper sealing of the oil pan.

Core plugs are used to seal the holes machined into the block to remove the sand after casting. Core plugs are often called freeze plugs. Occasionally, when coolant is not adequately protected with antifreeze, it freezes in the block; a core plug will pop out and prevent the block from cracking. People are not always that lucky, however, and that is not the purpose of core plugs.

Honing a cylinder is a machining process that prepares the surface for the installation of new piston rings.

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Chapter 12

Main caps with steel inserts

Girdle assembly

Figure 12-11 This all-aluminum, two-piece block engine uses a main girdle; all the main caps are formed in one casting and bored out to fit the crankshaft.

Figure 12-12 Bearings are fit into the main bores to protect the crankshaft. This is an example of a two-bolt main block.

Main Bore The main bore is a straight hole drilled through the block to support the crankshaft. The main caps form the other half of the main bore and bolt onto the block to form round holes for the crankshaft bearings and journals.

Bearing inserts are soft-faced bearings used to protect the crankshaft main and rod journals as well as the camshaft journals.

The main bore holds the crankshaft. The bore is supported by the webbing in the lower part of the block casting. Some blocks use a cast-iron girdle that bolts onto the main caps to increase rigidity of the bore (Figure 12-11). Main-bearing caps are cast separately and then machined to bolt on the bottom of the block. The main bore is then line- or alignbored to form the round hole between the bottom of the block and the main caps. The main caps are bolted in place, while a long boring bar passes through the end of the block. Because the boring bar will never turn exactly true, particularly toward the end of its reach, the bores will only be round if the same cap is installed in the same direction for each bore. The main bores must be in perfect alignment with each other in a straight line. If the main bores are misaligned, rapid and uneven main bearing wear will occur. The main caps are held in place by two, four, or six bolts. A two-bolt main cap is the most common (Figure 12-12), but many modern lightweight and performance engines use a four-bolt main cap. The extra bolts may be next to each other (parallel), or they may be bolted in from the sides (cross bolted). This design holds the crankshaft better and allows for less flexing when under higher stresses (Figure 12-13). Some engines use a six-bolt main cap. Main bearing inserts snap into the halves of the main caps. They provide a soft surface to support, lubricate, and protect the crankshaft. They also prevent the main bore from wear; the crankshaft does not contact the main bores (Figure 12-12).

CRANKSHAFT The crankshaft withstands tons of force when the piston pushes the connecting rod down on the power stroke. It converts that reciprocating motion of the piston into useful rotary motion. Crankshafts may be made of cast iron, nodular iron, or forged steel. Cast-iron cranks are quite Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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241

Connecting rod–bearing journals

Main-bearing journals

Figure 12-13 This is a four-bolt main bearing cap.

Figure 12-14 The rod-bearing journals are offset from the centerline of the crank. The length of the offset times two is the engine’s stroke.

common on production vehicles. Forged crankshafts are stronger and are often found on high-performance vehicles, engines with forced induction systems, and diesel engines. The crankshaft is bolted into the main bore on its main-bearing journals. These are machined on the centerline of the crankshaft and support the weight and forces applied to the crankshaft. Crankshaft journals are machined and polished smooth to minimize bearing wear and friction. The journals actually ride on a thin film of oil between the bearing and the journal. The connecting rod–bearing journals or pins are offset from the centerline (Figure 12-14). The connecting rod clamps around these journals with a bearing insert in between to protect the crankshaft and the connecting rod. The offset places weight and pressure off the center of the crankshaft and provides leverage for the piston assembly to turn the crankshaft. The distance the connecting rod journals are offset from the centerline of the crankshaft is called the crankshaft throw. The throw determines the stroke of the engine. Rod journal offset times two equals the stroke. The throws are set so that pistons in opposite banks move in opposite directions to minimize engine vibration. This design cancels some of the forces applied to the crankshaft. Crankshafts have many different configurations, depending on the engine. They will usually be ground so that the cylinders fire in equal intervals during one full cycle. A four-cylinder engine produces a power stroke every 180 degrees; its rod journals are 180 degrees off of each other. A typical four-cylinder engine with a firing order of 1–3–4–2 will fire cylinder number 1 at 180 degrees of crank rotation, number 3 at 360 degrees, number 4 at 540 degrees, and complete the full cycle at 720 degrees with the firing of cylinder number 2. This puts cylinders number 1 and number 4 and cylinders number 3 and number 2 positioned at the same point in the cylinder during rotation (Figure 12-15). The connecting rod journals from an end view form a straight line above and below the main journals. Just like the four-cylinder engine, the flat-plane V8 crankshaft (Figure 12-16) produces a power stroke every 180 degrees, making it an even fire engine since there are no cylinders firing in between the pistons being at TDC (top dead center) and BDT (bottom dead center). Flat-plane crankshafts have less mass, making them lighter and allowing them to rev faster and higher. They have more torsional vibration and can be fired alternating banks for smoother running. A V6 engine typically produces a power stroke every 120 degrees of crank rotation. This is called an even-firing V6. The journals on the crankshaft are splayed. In this engine, on one throw, two journals are offset and separated by 30 degrees in this case (Figure 12-17). Other V6 engines use one throw with two equal journal surfaces. This means that two rods

Main-bearing journals are machined along the centerline of the crankshaft and support the weight and forces applied to the crankshaft. Connecting rod– bearing journals are offset from the crankshaft centerline to provide leverage for the piston to turn the crankshaft. Crankshaft throw is the measured distance between the centerline of the rod journal and the centerline of the crankshaft main journal. Crankshaft throw multiplied by two equals the piston stroke.

A splayed crankshaft is a crankshaft in which the connecting rod journals of two adjacent cylinders are offset on the same throw.

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Chapter 12

180°

90°

90°

1

4

3

1

2

3

4

2

180°

90° 4 cylinder

90° V8

120° 120°

120°

120° 120°

1

3

120°

2

120°

120°

120°

V6

V6 splayed

Figure 12-15 Typical connecting rod throw offsets. Individual offset crankpins

1-2

7-8

3-4

Figure 12-16 A flat-plane crankshaft.

5-6

Figure 12-17 A splayed crankshaft.

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Engine Block Construction

Figure 12-18 Two rods share one journal on this V8 crankshaft. Notice the oil holes to feed each of the rod bearings.

will rotate together. The throws are machined at 120-degree intervals around the crankshaft. This produces an odd-firing V6. cylinders fire at 90 degrees, then after 150 degrees of rotation, then again after 90 degrees, and on through the two full revolutions of the crankshaft that create a cycle. An even-firing V8 crankshaft has four throws each with two journals on them (Figure 12-18). The crankshaft produces power strokes every 90 degrees of crank rotation. This is what makes a V8 such a smooth-running engine; the crankshaft is rotated by a connecting rod every 90 degrees. This leaves little time for the crankshaft to speed up or slow down.

Crankshaft Oil Holes The crankshaft is drilled to provide oil passages that feed each rod and main journal. The oil is held under pressure by the tight fit between the journal and the bearing. The bearing has an oil hole in it that lines up with the drilled hole in the crankshaft.

Crankshaft Fillets The fillet on the journal is used to increase the strength of the journal (Figure 12-19). This joint area is subject to high stress and is a common location for cracks. Because sharp corners are weak, manufacturers call for a curved fillet of a specific radius. The fillet is increased for applications requiring severe duty. Most fillets are formed by grinding the joint. Some turbocharged or high-performance engines use a process of rolling the fillet. This is done by rolling hardened steel balls under pressure on the joint. This causes the metal at the joint to become compacted and tightens the grain structure, thus

Fillets

Journal

Figure 12-19 The fillet strengthens the crankshaft journal. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 12

strengthening the crankshaft by as much as 30 to 40 percent. The fillet is not usually a wear area unless the bearing is worn, but the fillet is an area where the crankshaft can crack and should be carefully inspected. If the journal requires machining, the fillet should be reground to the proper radius. The crankshaft is also subject to lateral forces. These come from clutch engagement and automatic transmission loads. The lateral movement of the crankshaft is controlled by a thrust bearing and a thrust surface on the crankshaft. The thrust bearing is usually attached vertically to the sides of one main bearing.

Crankshaft Counterweights Crankshaft counterweights are positioned opposite the connecting rod journals and balance the crankshaft.

The crankshaft is cast or forged with large counterweights that oppose the rod journals. The counterweight overcomes the total weight of the rod-bearing journal, bearing, connecting rod, piston pin, and piston. These help support the crankshaft and even out the speed changes as the crank rotates through firing impulses. Crankshafts that use (only) their counterweights for balance are “internally” balanced. Externally balanced crankshafts depend on the harmonic balancer and flywheel or flexplate (in addition to the counter weights) to absorb vibration. You will often see holes drilled in the counterweights. These are drilled when the crankshaft is balanced as it spins with rods and pistons attached. Holes also lighten the crank; you may see lightening holes on the sides of the throws as well.

Crankshaft Construction Many manufacturers construct their crankshafts from gray cast iron. This construction is strong enough for most applications. Some engine applications require additional strength above what gray cast iron can provide; in these instances, nodular iron is often used. A cast-iron crankshaft is identifiable by its straight cast mold parting line (Figure 12-20). In other applications, such as some turbocharged engines, a forged mediumcarbon steel crankshaft (carbon content between 0.30 and 0.60 percent) is used. Highperformance engines may use a crankshaft using chromium and molybdenum (sometimes called chrome-moly) alloys to increase its strength. The forging process condenses the grain of the steel and increases its strength. Because of the density of the steel, these crankshafts weigh more than a cast-iron crankshaft. To lighten the weight, some manufacturers hollow the rod-bearing journals. Forged crankshafts designed for use in V8 and in-line, six-cylinder engines must be twisted to achieve the desired throw offset. This process is done immediately after the crankshaft is forged, while the meal is still hot. A forged crankshaft can be identified by the staggered die parting lines because of this twisting (Figure 12-21). Case-hardening crankshafts protects the journals from wear and fractures. Many manufacturers use a case-hardening process called ion nitriding. The component is placed

Figure 12-20 Casting lines on a cast-iron crankshaft.

Figure 12-21 Casting lines on a forged crankshaft.

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245

into a pressurized chamber filled with hydrogen and nitrogen gases. An electrical current is then applied through the component. This changes the molecular structure of the metal and allows the induction of the gases into the surface area of the journal.

A BIT OF HISTORY Bentley Motors was founded in 1919, and within a short span of time, the Bentley automobile became a refined and complex “silent sports car.” In 1931, Bentley acquired Rolls Royce, and thereafter the Bentley automobile became associated with it. Today, with a $500-million investment, Bentley Motors is focusing on designing and building automobiles of world-class standards. All Bentley automobiles go through a 154-point inspection designed by Bentley engineers in the factory.

CAMSHAFT The camshaft may be fitted in the block (Figure 12-22). It rides on bearings placed in the camshaft bore. A thrust plate typically limits the camshaft end play. Refer to Chapter 10 of this manual for a review of the full characteristics and functions of the camshaft.

LIFTER BORES When a block contains the camshaft, it also has lifter bores drilled above the camshaft lobes. These bores are slightly off center from the centerline of the camshaft lobe so that the convex face of the lifter turns the lifter in its bore. Lifter bores must be clean and free of coring to provide a smooth surface for the lifters to ride on.

Shop Manual Chapter 12, page 537

HARMONIC BALANCING A two-piece harmonic balancer is used on the front end of the crankshaft. It is used to absorb the torsional vibrations of the crankshaft created as the crankshaft tries to speed up due to firing impulses on cylinders. At the same time, another cylinder is trying to slow the crankshaft down as it pushes against air pressure on the compression stroke. The inner piece is bolted to the crankshaft. An inertia ring is bonded with rubber to the inner ring. As the crankshaft winds and unwinds, the twisting of the inertia ring and the rubber ring absorb some of the vibrations (Figure 12-23). If the bonding fails, the two rings will separate and you will need to replace the harmonic balancer. A faulty harmonic balancer can cause engine vibration, resulting in a broken crankshaft.

Harmonic balancers are used to control and compensate for torsional vibrations.

Torsional vibration is the result of the crankshaft twisting and snapping back during each revolution.

Figure 12-22 The camshaft may be housed in the block or in the head.

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Chapter 12 Pulley

Rubber damper for torsional vibration

Piston

Rubber damper for vertical vibration

Vibration damper center area Crank twist and snap-back action

Hub

Figure 12-24 Harmonic balancer action. Rubber-like material Counterweight area

Crankshaft

* Harmonic balancer scale exaggerated.

Figure 12-23 Dual-mode harmonic balancer.

Many of today’s engines use dual-mode harmonic balancers (Figure 12-24). The first mode eliminates torsional vibration, and the other mode eliminates vertical vibration. Many harmonic balancers are pressed onto the end of the crankshaft, and a square key fits into a matching keyway in the crankshaft and harmonic balancer to prevent rotation. A bolt and washer usually retain the harmonic balancer on the end of the crankshaft.

AUTHOR’S NOTE One day a customer had her vehicle towed in. The engine had stopped running after developing a very serious knocking noise from the bottom end. While disassembling the engine, I noticed that the harmonic balancer had separated badly. The result: the crankshaft had broken in half!

The torque converter mounts to the crankshaft through a flexplate. Its weight and fluid coupling do a fine job of maintaining a more constant crankshaft speed.

FLYWHEEL

Crankshaft specifications, stampings, part numbers, and tolerances may be different if an engine is mated with the vehicle option of an automatic or a manual transmission.

The flywheel is a large round disc of heavy mass attached to the rear end of the crankshaft to smooth the rotation of the crankshaft (Figure 12-25). It helps the crankshaft speed remain more constant between firing pulses by storing inertial energy. The outer ring, the ring gear, is pressed on to provide teeth for the starter pinion gear to turn the engine over. The machined center surface provides a surface for the clutch disc to grab onto to transmit the rotation of the crankshaft to the transmissions. Flywheels are used only on engines mounted to a manual transmission. An automatic transmission is mounted to the engine by a light flexplate that bolts to the torque converter. The torque converter is filled with transmission fluid and is as heavy as a flywheel and clutch assembly. The fluid coupling of the torque converter does an excellent job of helping maintain a constant crankshaft speed.

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Engine Block Construction

Flywheel Crankshaft

Figure 12-25 The flywheel is attached to the rear of the crankshaft. A flywheel is used with a manual transmission. A flexplate is used with a manual transmission.

SHORT BLOCKS, LONG BLOCKS, AND CRATE ENGINES Sometimes an engine block, the heads, or both are damaged badly enough that it becomes more cost-effective to replace the failed component(s) rather than machine or recondition it. New or rebuilt short or tall blocks are available for most engines. In addition, “crate” engines, usually supplied by an aftermarket company, are available fully assembled and rebuilt. The option of replacing a seriously damaged engine with a crate engine has become a very popular option in the past several years. Crate engines are remanufactured on assembly lines and are often cheaper than the cost of parts, machining, and labor to rebuild an engine in house (Figure 12-26).

Figure 12-26 This remanufactured engine comes with bored cylinders, polished or new crankshafts, refurbished and balanced connecting rods, and new rings, pistons, and bearings.

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248

Chapter 12

SUMMARY ■

■ ■ ■ ■

The bottom end of the engine is made up of the block, crankshaft, pistons, and connecting rods. The cylinder block may be cast iron or aluminum. Cylinders are typically integral on a cast-iron block, as are steel sleeves on aluminum blocks. The block’s main bore holds the crankshaft. The main bore is line-bored with the caps in place. Main caps must be installed in their original locations and in the same direction.

■ ■ ■ ■ ■ ■

Crankshafts may be made of cast iron, nodular iron, or forged steel; forged cranks are stronger. The crankshaft spins on its main journals. The connecting rod journals are offset from the centerline, which determines the stroke. The connecting rod transmits combustion forces to spin the crankshaft. The harmonic balancer bolts to the front of the crankshaft to reduce torsional vibration. The flywheel or torque converter helps maintain crankshaft speed between power pulses.

REVIEW QUESTIONS Short-Answer Essays 1. Briefly explain how a cylinder block is formed. 2. Describe the advantages and disadvantages of an aluminum block. 3. What are the advantages of two-piece blocks? 4. Why must a main cap be installed in its original location and direction? 5. What is the purpose of the crankshaft? 6. How is the stroke of an engine determined? 7. Explain the purpose of the crankshaft fillet. 8. Explain why lifter bores are off center from the center of the camshaft lobe. 9. What is the purpose of a dual-mode harmonic balancer? 10. Explain the purpose of the flywheel.

Fill-in-the-Blanks 1. The _______________ _______________or main girdle is the lower portion of a two-piece block. 2. _______________ _______________ _______________blocks are significantly lighter than cast-iron blocks. 3. The passages that allow oil to flow throughout the engine are called _______________. 4. _______________ _______________are used to seal holes drilled to remove sand from the block casting process.

5. Bores are _______________ _______________ at the factory to provide good cylinder wall lubrication with minimum wear. 6. The _______________ _______________ holds the crankshaft. 7. _______________ crankshafts are stronger than _______________ crankshafts. 8. An eight-cylinder engine produces a power stroke every _______________ degrees of engine rotation. 9. The harmonic balancer reduces _______________ _______________. 10. A _______________ engine is a fully assembled remanufactured engine.

Multiple Choice 1. Aluminum blocks often use. A. integral bores. B. steel housings. C. steel liners. D. cast-iron main girdles. 2. A harmonic balancer has separated. The response the technician should take is to A. reseal the bond with rubber Loctite. B. replace the inertia ring. C. replace the crankshaft; it is likely cracked. D. replace the whole harmonic balancer.

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3. An engine bedplate. A. reduces vibrations. B. contains the main-bearing caps. C. adds strength to the block. D. All of the above.

8. A dual-mode harmonic balancer reduces. A. torsional and vertical vibrations. B. crankshaft end thrust and torsional vibration. C. speed fluctuations and torsional vibrations. D. vertical vibrations and crankshaft end thrust.

4. On an even-firing V6 engine with a splayed crankshaft, the throws on the splayed connecting rod journals are offset. A. 10 degrees. C. 35 degrees. B. 30 degrees. D. 45 degrees.

9. The purpose of core plugs is. A. to fully drain coolant during engine service. B. to prevent the block from freezing. C. to remove the sand after casting. D. to provide cooling jackets to remove excess heat.

5. The crankshaft is balanced by the _______________ to overcome the weight of the rod journal, piston pin, connecting rod, and piston. A. Harmonic balancer B. Fillet C. Counterweights D. Flywheel 6. The lifter bores are offset from the camshaft lobe to. A. allow the camshaft to turn. B. spin the valve. C. turn the pushrod. D. rotate the lifter. 7. Each of the following is a crankshaft material, except: A. Gray cast iron B. Nodular iron C. Chrome-moly alloys D. Forged aluminum

10. While discussing V8 crankshafts, Technician A says that a crate engine built for a vehicle with an automatic transmission may have a different crankshaft than the same one built for a manual transmission. Technician B says that a flat-plane crankshaft is heavier and takes up more space than a cross plane crankshaft. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

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CHAPTER 13

PISTONS, RINGS, CONNECTING RODS, AND BEARINGS

Upon completion and review of this chapter, you should understand and be able to describe: ■ ■ ■ ■

The function and design of engine bearings. The importance of proper bearing oil clearances. The design and function of pistons. The methods used in piston design to control heat expansion.

■ ■ ■ ■ ■

The advantages of cast, forged, and hypereutectic cast pistons. The purpose of piston pin offset. The purposes of piston rings. The design and materials of piston rings. The design and function of the connecting rods.

Terms To Know Balance shaft Bearing crush Bearing spread Blow-by Cam ground pistons Compression rings

Connecting rod bearings Locating tab Major thrust surface Minor thrust surface Offset pin Oil control rings

Oversize bearings Tapered pistons Thrust bearing Undersize bearings

INTRODUCTION The components within the engine block, the pistons, piston rings, connecting rods, and engine bearings, all play a critical role in transmitting the power of combustion from the top of the piston to the rod journal of the crankshaft to spin the engine. The piston is forced downward when combustion peaks just after TDC on the power stroke. The piston rings seal the small gap between the piston and the cylinder wall to use all the pressure of combustion. The connecting rods connect the piston to the crankshaft, delivering the reciprocating motion of the piston to the rotating crankshaft. Soft-coated engine bearings are held in the main, connecting rod, and camshaft bores to protect the crankshaft and camshaft. A thin film of oil is held between the bearing and the journal to reduce friction and minimize wear. Piston rings; main, connecting rod, and camshaft bearings; and timing chains are the main wear items in an engine block. Each of the bottom end components is carefully designed to match the characteristics of the engine. By knowing how these components are designed and should perform, you will be better able to evaluate their condition during engine repairs.

BEARINGS Bearings (bearing inserts) are used to protect the main and connecting rod journals of the crankshaft and carry the rotational loads (Figure 13-1). A similar type of bearing is used on the camshaft when it is in the block. The camshaft bearings are one piece rather than two, but 250

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Pistons, Rings, Connecting Rods, and Bearings

Figure 13-1 This is one half of a set of new aluminum-coated main bearings.

their materials and characteristics are nearly the same as those used to protect the crankshaft. The engine bearings are designed to wear before the crankshaft. The bearings snap into the main caps and connecting rod caps and are then bolted around the crankshaft journals. The clearance between the bearing and the journal is critical. The clearance allows a thin film of oil to lubricate the bearing and the crankshaft. That oil also absorbs the pounding of the crank as the power stroke forces it downward in the main bores. The crankshaft should spin on a film of oil and not contact the bearing (Figure 13-2). The oil pump sends oil under pressure through the holes drilled in the crankshaft through an oil hole in the bearing into this small clearance. The correct bearing clearance allows a calibrated amount of oil to leak out past the side of the bearings so the oil is constantly refreshed. When the bearing clearances become too great, more oil leaks out and engine oil pressure decreases. This loss of oil pressure results in a decrease in the oil film strength. The crankshaft will knock in its bore and cause rapid wear and distortion of the bearings and crankshaft. If the engine is not repaired promptly, the damage to the crankshaft and bearings can become so severe that the bearings spin with the crankshaft in their bores. When bearings spin in their bores, they can destroy the main bores, connecting rod bores, or camshaft bores and even cause the engine to seize. You will usually replace an engine with this type of severe damage to the block and crankshaft. Block

Main bearing journal

Oil film Main bearing

Figure 13-2 The crankshaft should ride on a film of oil roughly 0.001 inch thick. That is enough to reduce friction and protect the crankshaft. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Bearing Materials Engine bearings are made in halves that snap into the main and connecting rod bores and caps. The back of the bearings is steel to provide strength to carry the tremendous loads impressed by the crankshaft. On top of the load bearing shell are layers of soft metal to protect the crankshaft. Many different materials are used in the construction of bearings. The main concern of the manufacturers is to achieve a bearing construction that will have these desirable characteristics: 1. Surface action. The ability of the bearing to withstand metal-to-metal contact without being damaged. 2. Embedability. The ability of the bearing material to tolerate the presence of foreign material. 3. Fatigue resistance. The ability of the bearing to withstand the stress placed upon it. 4. Corrosion resistance. The ability of the bearing to withstand the corrosive acids produced within the engine. 5. Conformability. The ability of the bearing material to conform to small irregularities of the journal. Given that no single material will have all of these characteristics, most bearings are constructed using multilayers of different materials. The backing is usually made of steel; then additional lining material is added. The most common materials used include the following: 1. 2. 3. 4.

Babbitt Sintered copper-lead Cast copper-lead Aluminum

To assist the technician in the selection of bearings, most manufacturers use a part number suffix to identify the bearing lining material; for example, a Federal Mogul bearing with the part number 8-3400CP indicates the bearing is steel-backed copper-lead alloy with overplate. The following chart provides the codes used: Part Number Suffix

Lining Material and Application

AF

Steel-backed aluminum alloy thrust washer

AP

Steel-backed aluminum alloy with overplate connecting rod or main bearings

AT

Solid aluminum alloy connecting rod or main bearings

B

Bronze-backed babbitt connecting rod or main bearings

BF

Steel-backed bronze or babbitt thrust washers

CA

Steel-backed copper alloy connecting rod or main bearings

CH

Steel-backed copper-lead alloy with overplate connecting rod and main bearings for performance applications

CP

Steel-backed copper-lead alloy with overplate connecting rod and main bearings

DR

Steel-backed babbitt, steel-backed copper-lead alloy, or solid aluminum camshaft bushing

F

Bronze-backed babbitt, bronze or aluminum thrust washers

RA

Steel-backed aluminum alloy connecting rod and main bearings

SA, SB, SBI, SH, SI, SO

Steel-backed babbitt connecting rod and main bearings

TM

Steel-backed copper alloy with thin overplate connecting rod and main bearings

W

Camshaft thrust washer Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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When choosing replacement bearings, you will usually use original equipment quality components or updated designs as recommended by the parts supplier.

Bearing Characteristics Figure 13-3 provides common nomenclature used with insert-type bearings. Most main and connecting rod bearings are designed to have a certain amount of spread. Bearing spread is provided by manufacturing the bearing inserts so they have a slightly larger curvature compared to the curvature of the rod bearing or cap. This design ensures positive positioning of the bearing against the total bore area. When the bearing is installed into the bore, a light pressure is required to set the bearing (Figure 13-4). In addition to bearing spread, most main and connecting rod bearings are designed to provide bearing crush (Figure 13-5). When the bearing half is installed in the connecting rod or cap, the bearing edges protrude slightly from the rod or cap surfaces. When the two halves are assembled, the crush exerts radial pressure on the bearing halves and forces them into the bore. Proper crush is important for heat transfer. If the bearing is not tight against the bore, it will act as a heat dam and not transfer the heat to the engine block. Bearing spread and bearing crush also help prevent the bearing from spinning in its bore as rotational friction acts on it.

Bearing spread means the distance across the outside parting edges is larger than the diameter of the bore.

Bearing crush refers to the extension of the bearing half beyond the seat.

Length Height

Gauge diameter (spread)

Annular groove Oil hole

Back thickness

End chamfer Distribution groove

Parting line chamfer

Thrust face

Bar gauge

Locating tab

Total wall thickness Lining thickness

Flange diameter

Length

Flange oil pocket

Eccentric wall thickness

Rod and main bearings

Thrust bearings

Figure 13-3 Bearing nomenclature.

Crush

Bearing Bearing

Housing Housing bore

Figure 13-4 Designing the bearing with a certain amount of spread ensures positive positioning of the bearing against the total bore area.

Figure 13-5 Bearing crush exerts radial pressure on the bearing halves and forces them securely into the bore.

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Chapter 13

The locating tab is a tab sticking out of bearing inserts that fits in a groove in the block, main bearing cap, connecting rod, or connecting rod cap to prevent insert rotation.

To ensure proper installation of the bearing in the bore, most manufacturers use a locating tab (Figure 13-6). A protruding tab at the parting of the bearing halves is set into a slot in the housing bore. When properly installed, the tab will locate the bearing, preventing it from shifting sideways in the bore.

Main Bearings Main bearings carry the load created by the movement of the crankshaft. Most of these bearings are insert design. The advantages of this design include ease of service, variety of materials, and controlled thickness. Split bearings surround each main bearing journal. The bearings are supplied oil under pressure from the oil pump through oil passages drilled in the engine block and crankshaft (Figure 13-7). The crankshaft does not rotate directly on the main bearings; instead, it rides on a thin film of oil trapped between the bearing and the crankshaft. If the journals are worn and become out-of-round, tapered, or scored, the oil film is not formed properly. This will result in direct contact between the crankshaft and bearing and will eventually damage the bearing, crankshaft, or both. Soft materials are used to construct the bearings in an attempt to limit wear of the crankshaft. Oil Grooves. Providing an adequate oil supply to all parts of the bearing surface, particularly in the load area, is an absolute necessity. In many cases, this is accomplished by the oil flow through the bearing oil clearance. In other cases, however, engine operating conditions are such that this oil distribution method is inadequate. When this occurs, some type of oil groove must be added to the bearing. Some oil grooves are used to ensure an adequate supply of oil to adjacent engine parts by means of oil throw-off. Oil Holes. Oil holes allow for oil flow through the engine block galleries and into the bearing oil clearance space. Connecting rod bearings receive oil from the main bearings by means of oil passages in the crankshaft. Oil holes are also used to meter the amount of oil supplied to other parts of the engine; for example, oil squirt holes in connecting rods are often used to spray oil onto the cylinder walls. When the bearing has an oil groove, the oil hole normally is in line with the groove. The size and location of oil holes are critical. Therefore, when installing bearings, you must make sure the oil holes in the block line up with holes in the bearings.

Oil enters at the main-bearing journals

Locating lug

Oil gallery Recess

Figure 13-6 A protruding tab at the parting of the bearing halves is mated to a slot in the housing bore. The tab locks the bearing to prevent it from spinning or shifting sideways.

Oil comes out to lubricate the connecting rod journals

Figure 13-7 Internal passages in the crankshaft send lubrication to the main and connecting rod bearings.

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Thrust Bearings The crankshaft is fitted with one thrust bearing to limit end play within the block (Figure 13-8). There must be some clearance for the crankshaft to move horizontally (end to end), to prevent it from seizing as components heat up. The thrust bearing protects the crank from slamming against the block as it moves forward and backward in its bore. Under acceleration, the crankshaft will be forced toward the back of the block. A thrust bearing allows a thin film of oil between a soft bearing and the crankshaft to absorb this force. The thrust bearing is often one of the main bearings, with flanges on the sides to control crank end play (Figure 13-9). It may be positioned at an end of the crank or in the middle. Some thrust bearings are not part of a main bearing; they can be multipiece (Figure 13-10). In this case, they are called thrust washers. Thrust bearings will typically wear faster when the engine is attached to a manual transmission because the clutch friction disk is constantly being engaged and disengaged from the flywheel while accelerating. This extra stress places horizontal loads on the crankshaft that are not found when the engine is coupled with an automatic transmission. Some manufacturers will have a different specification for the crankshaft end play. You will measure crankshaft end play during engine disassembly and reassembly to be sure it is within specifications.

The thrust bearing prevents the crankshaft from sliding back and forth by using flanges that rub on the side of the crankshaft journal.

Crankshaft end play is the measure of how far the crankshaft can move lengthwise in the block.

Rod Bearings Split bearings surround each connecting rod journal. Like the main bearings, the connecting rod bearings do not rotate directly on the crankshaft. They allow the rod journal to rotate on a thin film of oil trapped between the bearing and the crankshaft. Journals that are worn, out-of-round, tapered, or scored will not maintain this oil film, resulting in damage to the bearing, crankshaft, or both. Most main and rod bearings are designed with a bearing crown to maintain close clearances at the top and bottom of the bearing. This is the area where most of the loads are applied. The crown also allows increased oil flow at the sides of the bearing (Figure 13-11). In addition, most bearings have a beveled edge to provide room for the journal fillet.

Connecting rod bearings are insert-type bearings retained in the connecting rod and mounted between the large connecting rod bore and the crankshaft journal.

Bearing Oil Clearances There must be a gap or clearance between the inside diameter of the bearing face and the outside diameter of the journal of the main, connecting rod, and camshaft (if insert bearings are used). This clearance allows engine oil pressure to hold a film of oil within the clearance and prevent too much oil from leaking out. When the clearance becomes too great, either from wear of the bearing or the crankshaft journal, engine oil pressure is reduced. The bearing oil clearances provide a calibrated “leak” of oil from between the bearing and the journal. The clearances must be within the specifications to provide good oil pressure, prevent knocking, and protect the journal from wear. Many modern

Crankshaft

Thrust bearings

Figure 13-8 A flanged thrust bearing.

Figure 13-9 This thrust bearing has a soft aluminumcoated side flange to cushion crankshaft movement back and forth in the block.

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Chapter 13 Parting face

Figure 13-10 A multiplepiece thrust bearing.

Bearing crown

Figure 13-11 Bearing crown maintains close clearances at the top and bottom of the bearing, where most of the loads are applied.

Shop Manual Chapter 13, page 588

oil bearing clearances fall within the range of 0.0008 inch (0.0203 mm) to 0.002 inch (0.0508 mm). These are just typical clearances; always check the manufacturer’s specifications for the engine you are working on. Bearings are a wear item. They are designed to wear and protect the crankshaft or camshaft. They do wear out after high mileage and exposure to contaminated oil. When the engine is disassembled for repairs, it is customary to replace the main, rod, and cam bearings. When fitting new bearings, you will have to check the clearance to ensure that it is within the specified range. We will discuss this procedure in Chapter 13 of the Shop Manual.

Undersize and Oversize Bearings

Undersize bearings have the same outside diameter as standard bearings, but the bearing material is thicker to fit an undersize crankshaft journal. Oversize bearings are thicker than standard to increase the outside diameter of the bearing to fit an oversize bearing bore. The inside diameter is the same as standard bearings.

When a crankshaft is worn lightly and polished to be usable, bearings that are 0.001 and 0.002 inch undersize are often available. If the crankshaft has been ground to repair serious journal wear, undersize bearings can be fitted. These bearings are generally available in 0.010, 0.020, and 0.030 inch undersize. Metric undersized bearings may include 0.050, 0.250, 0.500, and 0.750 mm. Undersize means that the inside diameter of the bearings is smaller, to fit the reduced diameter of the crankshaft journals. Oversize bearings may be used when the block has been line bored to an oversized diameter. Oversize bearings are often available in 0.010, 0.020, 0.030, and 0.040 inch. Available metric oversized bearings are typically 0.250, 0.500, 0.750, and 1.000 mm. These bearings have a larger outside diameter than the standard bearing. The use of oversize and undersize bearings has decreased dramatically as component replacement has become more cost-effective than many complex machining operations. Some bearings are stamped with a code that allows the technician to check the size of the bearing that is currently in use. New bearings come stamped from the factory with the size correlation on it. Some engine blocks have a stamping on them that helps the technician indicate what size bearing came on the engine originally. If different sized bearings are installed in this type of engine, the technician should change this mark or remove it.

AUTHOR’S NOTE It has been my experience that most connecting rod and main bearing failures are caused by contaminated engine oil or lack of lubrication. Often the cause of failure is clear by the sludge in the oil pan, the coolant-contaminated oil, or the lack of oil in the crankcase. Try to determine the cause of the failure if it is premature. Most bearings should last the life of the engine; these days, that may reach 150,000 to 200,000 miles (241,402 to 321,870 km). Be sure to discuss the importance of regular oil and filter changes with your customers.

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A BIT OF HISTORY Isaac Babbitt invented his bearing material in 1839 using a mixture of tin, lead, and antimony. This tin-based babbitt was later replaced with a lead-based material. When lead-based babbitt was used in the first automotive engines, it was melted and then poured into the block and connecting rods. After the babbitt cooled, the correct oil clearance was achieved by hand scraping the excess material. Final adjustment of the bearings was accomplished by using shims between the bearing caps. Due to the nature of these early bearings, they often smeared under heavy loads. To decrease the oil clearance as the bearing wore, the caps were refilled. This operation was considered owner maintenance, and babbitt material was carried in the vehicle to make the necessary roadside repairs.

CAMSHAFT AND BALANCE SHAFT BEARINGS In an overhead valve (OHV) engine, the circular bearings are pressed into openings in the block (Figure 13-12). The camshaft journals are positioned in these bearings. The specified bearing clearance must be present between the camshaft journals and the bearings. Oil from the lubrication system is supplied through passages in the block to an opening in each camshaft bearing. The opening in the camshaft bearing must be properly aligned with the oil passage in the block. Excessive camshaft bearing clearance causes low oil pressure. During an engine rebuild, the camshaft bearings should be replaced. To make camshaft removal and replacement easier, the camshaft bearings on many engines are progressively larger from the back to the front of the block. Special tools are available to remove and replace the camshaft bearings. Balance shaft bearings are similar to camshaft bearings.

BALANCE SHAFTS Many engine designs tend to have inherent vibrations. The in-line four-cylinder engine is a good example of this, but other engines use balance shafts for varying reasons, including customer demand for smoothness. Even some V-style engines use balance shafts. Some engine manufacturers use a balance shaft to counteract this tendency (Figure 13-13). Four-cylinder engine vibration occurs when the piston is moving down during its power stroke. When the engine completes one revolution, two vibrations occur. The balance shaft rotates at twice the speed of the crankshaft. This creates a force that counteracts crankshaft vibrations.

The balance shaft is a shaft driven by the crankshaft that is designed to reduce engine vibrations.

Shop Manual Chapter 13, page 591

PISTONS The piston, when assembled to the connecting rod, is designed to transmit the power produced in the combustion chamber to the crankshaft (Figure 13-14). The piston must be able to withstand severe operating conditions. Stress and expansion problems are

Figure 13-12 Camshaft bearings in the cylinder block. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13 Retainer

Plug

Balance shaft

Piston

Connecting rod Gear

Figure 13-13 A balance shaft in a V6 engine. Rod big end bore

Figure 13-14 The forces of combustion push the piston down in the cylinder. The connecting rod bolts to the crankshaft and transmits this force.

compounded by the extreme temperatures to which the top of the piston is exposed. In addition, the rapid movement of the piston creates stress and high pressures. To control these stress conditions, most pistons are constructed from aluminum. The lightweight aluminum operates very efficiently in high-rpm engines. The piston has several parts, including the following (Figure 13-15):

Slipper skirts allow shorter connecting rods to be used. Part of the skirt is removed to provide additional clearance between the piston and the counterweights of the crankshaft. Without this recessed area, the piston would contact the crankshaft when the shorter connecting rods are used.

1. Land. Used to confine and support the piston rings in their grooves. 2. Heat dam. Used on some pistons to reduce the amount of heat flow to the top ring groove. A narrow groove is cut between the top land and the top of the piston. As the engine is run, carbon fills the groove to dam the transfer of heat. 3. Piston head (or crown). The top of the piston against which the combustion gases push. Different head shapes are used to achieve the manufacturers’ desired results (Figure 13-16). Most engines use flat-top piston heads. If the piston comes close to the valves, the recessed piston head is used to provide additional clearance. Different types of domed and wedged piston heads are used to increase compression ratios. 4. Piston pins (or wrist pins). Connect the piston to the connecting rod. Three basic designs are used: piston pin anchored to the piston and floating in the connecting rod; piston pin anchored to the connecting rod and floating in the piston; and piston pin full floating in the piston and connecting rod. 5. Skirt. The area between the bottom of the piston and the lower ring groove and at a 90-degree angle to the piston pin. The skirt forms a bearing area in contact with the cylinder wall. To reduce the weight of the piston and connecting rod assembly, many manufacturers use a slipper skirt. The piston skirt surface is etched to allow it to trap oil (Figure 13-17). This helps lubricate the piston skirt as it moves within the cylinder and prevents scuffing of the skirt. 6. Thrust face. The portion of the piston skirt that carries the thrust load of the piston against the cylinder wall. 7. Compression ring grooves. The two upper ring grooves used to hold the compression rings. 8. Oil ring groove. The bottom ring groove used to hold the oil ring. 9. Gas ports. Some pistons have holes drilled near the top compression ring to allow combustion gases behind the ring to force it out against the cylinder wall to improve sealing (Figure 13-18).

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Pistons, Rings, Connecting Rods, and Bearings Top compression ring

259

Cupped top

C. D.

C. D. Second compression ring

Oil rings

Expander

Flat head

Height

Cup head

Dome

Wrist pin

C. D.

Hump head

Height

Connecting rod

C. D.

Dome head

C. D.

Height

C. D.

Contour head

Fire dome head

C. D. = Compression distance Bearings

Figure 13-16 Some of the common piston head designs used in automotive engines.

Cap

Figure 13-15 The components of the piston and connecting rod assembly.

Gas ports

Machined etching

Figure 13-17 Some piston skirts have an etching machined into them to help trap oil to lubricate the skirt. Scuffing prevents oil from being trapped and causing increased friction and wear.

Figure 13-18 Some performance engines use gasported pistons to improve top ring sealing.

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Chapter 13

Thermal expansion of aluminum is about twice as much as iron. A piston is not a perfect circle shape; it is more of an oval shape. Cam ground pistons are oval shaped so that they can expand to a more perfect circle shape when heated. A tapered piston is narrower at the top of the piston where it will expand when heated to become a similar diameter.

Expansion Controls When combustion occurs, high temperatures and pressures are applied to the top of the piston. Some of this heat is transmitted to the piston body, causing the piston to expand. To control piston expansion, most pistons are cam ground. Cam ground pistons are made to be an oval shape when the piston is cold. The larger diameter of the piston is across the thrust surfaces. The thrust surfaces are perpendicular to the piston pin (Figure 13-19). On a cold piston, the thrust surfaces have a close fit to the cylinder wall while the surface around the piston pin has greater clearance. As the piston warms, it will expand along the piston pin. As it expands, the shape of the piston becomes more round. Pistons are also tapered from the top to the bottom. The top of the piston runs much hotter than the skirt due to its exposure to combustion gases. On tapered pistons, the top of the piston is manufactured with a narrower diameter than the bottom area of the skirt, to allow room for the excess expansion. When the piston is fully warm, the top is designed to fit the cylinder perfectly (Figure 13-20). To measure piston diameter, use the manufacturer’s guidelines; measuring at the wrong height could give you improper readings. Many manufacturers design their cast-aluminum pistons with steel struts located in the skirt area (Figure 13-21). The strut works to control the amount and rate of expansion. The struts are cast into the piston during manufacturing. Since steel and aluminum expand at different rates for the same temperature, the struts keep the skirt from expanding too much (Figure 13-22). This allows the manufacturer to use tighter clearances between the piston and cylinder to prevent the piston from rocking in the cylinder and generating noise. A graphite moly-disulfide coating is added to many modern piston skirts to reduce scuffing and increase durability (Figure 13-23). These lubrication coatings are helpful in reducing friction, to allow tighter piston-to-cylinder wall clearances. Many parts manufacturers offer replacement pistons with coatings. They are slightly more expensive but will increase the longevity of the piston and reduce cylinder wear.

Thrust surface B

Direction of expansion A

Piston pin hole Thrust surface

Figure 13-19 Cam ground pistons have the largest diameter across the thrust surfaces (A). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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B

Diameter B

Piston pin

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The piston is narrower at the top because it will expand more as the engine warms up.

Steel strut

Diameter A An exaggerated view of a cam ground piston shows that the pin side is narrower. It will expand to become round when it reaches normal operating temperature.

Figure 13-21 Some manufacturers use a steel strut to help control expansion and add strength to the piston.

Figure 13-20 The piston is cam ground (A) and tapered (B) to provide good cylinder fit when running at normal operating temperature. Expansion along the piston pin

Thrust surface

Struts

Figure 13-22 Steel struts in the piston help control piston expansion.

Lubrication patch

Figure 13-23 Some pistons have a coating on the skirts to reduce friction and improve piston fit in the cylinder. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Piston Pin Piston offset is used to provide more effective downward force onto the crankshaft by increasing the leverage applied to the crankshaft. The skirt that pushes against the cylinder wall during the power stroke is the major thrust surface. The skirt that pushes against the cylinder wall during the compression stroke is the minor thrust surface. An offset pin is a piston pin that is not mounted on the vertical center of the piston.

The pin boss accepts the piston pin to attach the piston to the connecting rod.

The piston is joined to the connecting rod by the wrist pin or piston pin. The piston pin bore is reinforced by a pin boss to support the huge forces transmitted to the connecting rod through the pin. The piston pin is often pressed into the piston on passenger car applications. Some higher-end engines and racing applications use full floating pins. A full floating pin is held in place by snap rings.

Piston Pin Offset Most manufacturers offset the piston pin to reduce piston slap (Figure 13-24). The connecting rod is angled to different sides on the compression and power strokes, causing the piston to rock from one skirt to the other at TDC. During the compression stroke, not as much force is exerted on the piston skirt as during the power stroke. Offsetting the piston pin hole toward the major thrust surface about 0.062 inch (1.57 mm) reduces the tendency of the piston to slap the cylinder wall as it rocks from the minor to the major thrust surface. During the compression stroke, the connecting rod pushes the minor thrust surface against the cylinder wall (Figure 13-25). The offset pin causes more of the combustion pressure to be exerted on the larger half of the piston head (Figure 13-26). This uneven pressure application causes the piston to tilt so the top of the piston contacts the cylinder wall on the minor thrust surface and the bottom of the piston contacts the cylinder wall on the major thrust surface. When the piston begins its downward movement, its upper half slides into contact with the major thrust surface (Figure 13-27). To assist in the installation of the piston, most manufacturers have a groove or other marking to indicate the side of the piston that faces the front of the block. On V-type engines, the pin offset for each bank is on opposite sides. This is because crankshaft rotation determines the major thrust surface side. If the pistons are installed in the wrong direction, it will cause excess friction and piston slap. Compression pressure

Identification mark Compression stroke

63D H

Front mark

Centerline of hole

Minor thrust surface

Centerline of piston

Figure 13-24 Some piston pins are offset to reduce piston slap. A forward marking on the piston ensures the offset will be in the correct orientation during reassembly.

Figure 13-25 During the compression stroke, the connecting rod forces the piston against the minor thrust side of the cylinder wall.

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Contact

Major thrust surface

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Power stroke

Contact

Figure 13-26 The offset pin causes more of the combustion pressure to be exerted on the larger half of the piston head, causing the piston to tilt and cushion the transition from the minor thrust side to the major thrust side. The illustration is exaggerated for clarity.

Figure 13-27 When the piston begins its downward movement, its upper half slides into contact with the major thrust surface.

AUTHOR’S NOTE I had a young man bring his newly restored, freshly rebuilt, and performance-modified engine in to diagnose a knocking noise. The noise was coming from the top of the block, and I suspected piston slap. After removing the cylinder head, I could see that the forward markings on the pistons were pointing toward the rear of the engine. After proper reassembly, the engine was quiet and powerful; he had done fine work aside from the piston assembly problem.

Piston Speed As the piston moves up and down in the cylinder, it is constantly changing speeds. At top and bottom dead center, the speed of the piston is zero. It then immediately accelerates to maximum speed. This action places heavy loads on the piston pin and pin boss. Today, most pistons are constructed of aluminum instead of iron. Because of its mass, a piston made of iron will take more energy to accelerate and decelerate than one made of aluminum. This would accelerate wear on the piston pin, connecting rod, crankshaft, and bearings. It would also decrease the power output and efficiency.

PISTON DESIGNS AND CONSTRUCTION If it is determined that the pistons require replacement, several piston designs are available from manufacturers and aftermarket suppliers. The technician must be capable of selecting the correct design for the engine application. This usually means replacing the piston Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Dish depth

Figure 13-28 This piston has valve relief cutouts to prevent the valves from knocking the top of the piston. You can also see the forward marking dot on the right side of the piston head.

It is important to recognize that over 90 percent of technicians will work on restoring engines to their original operating condition. Very few technicians will actually find work modifying engines to improve performance. If you understand the basic principles of engine operating and service presented in this text, you will easily be able to transfer that knowledge to highperformance work if you find yourself in that often-coveted position.

Figure 13-29 Dished piston design.

with the same design as the one removed; however, if the engine is to be modified, piston selection is one aspect in increasing engine performance and durability. It is possible to change the compression ratio of the engine by changing the head design of the piston. Most original equipment pistons have a flat head. These pistons may require valve reliefs machined into the head to prevent valve-to-piston contact (Figure 13-28). The depth of the relief is determined by camshaft timing, duration, and lift. A dished piston is designed to put most of the combustion chamber into the piston head and lower the compression ratio (Figure 13-29). When adding a turbocharger or supercharger to an engine, you may need to lower the compression ratio by installing dished pistons. A domed piston will fill the combustion area and increase the compression ratio (Figure 13-30). Other designs are variations of these three types. In addition to changing compression ratio, piston head design can increase the efficiency of the combustion process by creating a turbulence to improve the mixing of the air and fuel.

Dome height

Figure 13-30 Domed piston designs can increase the compression ratio and add turbulence to the combustion chamber.

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AUTHOR’S NOTE Changing the piston design can have a negative impact on emissions. For all street-application vehicles, it is illegal to raise the compression ratio of an engine by changing pistons or to increase emissions above the standard to which the vehicle was built. While modified parts are readily available and widely used, they come with a warning that they are for off-road use only. Making modifications to an engine that has to pass an emissions test can cause test failures and costly repairs. As a technician, you are responsible for maintaining the integrity of the emissions on a customer’s vehicle.

Another consideration when replacing pistons is construction type. Weight and expansion rates of the piston are important aspects in today’s high-rpm engines. The use of aluminum pistons reduces the weight of the assembly and the load on the crankshaft. Construction methods also affect the piston’s expansion rate and amount. Most original equipment pistons are made of cast aluminum. These are very capable of handling the requirements of most original equipment engines. The advantage of cast pistons is their low expansion rate. The expansion rate is low because the grain structure of cast is not as dense as other manufacturing processes. This low expansion rate allows the engine manufacturer to tighten the piston clearance tolerances, helping to prevent piston slap and rattle when the engine is cold. Forged pistons are stronger due to their dense grain structure. The tighter grain structure allows the piston to run about 20 percent cooler than a cast piston. Depending on the alloy used in the aluminum, the expansion rate may be greater than cast. This requires additional piston clearance and may result in cold engine piston rattle. Alloys have been developed in recent years that reduce the expansion rate of forged pistons. Consequently, it is important to follow the piston manufacturer’s specifications for piston clearance. A third alternative is hypereutectic cast pistons. Most cast pistons are constructed with about 9.5 percent silicon content, while forged pistons have between 0.10 and 10  percent, depending on the aluminum used. Silicone is added to help provide lubrication and increase strength. Hypereutectic pistons contain between 16 and 22 percent silicone. Aluminum can only dissolve about 12 percent silicone and hold it in suspension. The silicone is added when the aluminum is molten and dissolved. At the 12 percent level, the silicone remains dissolved when the piston cools. Normally, silicone added above this saturation point will not dissolve and settles at the bottom of the mold. Hypereutectic casting keeps the undissolved silicone dispersed throughout the piston by closely monitoring and controlling the heating and cooling rates during the manufacturing process. Hypereutectic casting increases the temperature fatigue resistance of the piston. This allows the piston to be made thinner than most cast pistons, reducing the weight of the piston. The strength of hypereutectic pistons falls between cast and forged. The drawback to this piston construction is that silicone can reduce the piston’s ability to conduct heat away from the combustion chamber. Although its temperature fatigue is increased, the piston runs hotter than cast and may cause detonation. It is possible to tell if the piston is forged or cast by looking at the underside of the piston head. Cast pistons have mold dividing lines, while forged pistons do not have these parting lines. Gasoline direct injection (GDI) pistons have special domes or crowns to handle extremely lean fuel mixtures (Figure 13-31). Diesel pistons also have a different design because the combustion chamber is part of the piston (Figure 13-32).

Shop Manual Chapter 13, page 594

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Figure 13-31 GDI pistons are designed to handle leaner air-fuel mixtures and higher compression ratios.

Figure 13-32 Diesel pistons are shaped differently than gasoline pistons. A diesel piston uses the bowl in the center of the piston as part of the combustion chamber and ignition point.

AUTHOR’S NOTE GDI increases power and fuel economy while lowering emissions. Engine-related problems are mostly due to carbon buildup on the valves, piston rings, and fuel injector. Lack of maintenance or the use of incorrect oil can result in heavy valvetrain wear due to the friction of the high-pressure pump running off of the camshaft.

PISTON RINGS Blow-by refers to compression pressures that escape past the piston. Compressions rings are the top rings in a piston assembly that provide cylinder sealing during the compression and power strokes.

Ring seating is accomplished by the movement of the piston in the cylinder. If the cylinder is properly conditioned, this movement laps the rings against the wall.

For the engine to produce maximum power, compression and expansion gases must be sealed in the combustion chamber. To control blow-by, the piston is fitted with compression rings. The rings seal the piston to the cylinder wall, sealing in combustion pressures. In addition, oil rings are used to prevent oil from reaching the top of the piston. Oil in this area will result in blue smoke being expelled from the exhaust system. Compression rings are located on the two upper lands of the piston (Figure 13-33). The compression rings form a seal between the piston and the cylinder wall. To provide a more positive seal, many manufacturers design one or more of the compression rings with a taper (Figure 13-34). The taper provides a sharp, positive seal to the cylinder wall. This style of ring must be installed in the correct position. A dot or other marking is usually provided to indicate the top of the ring. Compression rings

Oil control ring

Clearance

Block

Figure 13-33 The top piston ring grooves are used to hold the compression rings. The rings seal against the cylinder wall. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Cylinder wall

Combustion pressure

No. 2 piston ring

Block

Taper

Figure 13-34 Some compression rings are designed with a chamfer or taper. These types of rings may be directional; always look for a top marking during installation.

Figure 13-35 The rings are designed to use combustion pressures to exert additional outward forces of the rings against the cylinder walls.

In addition to tapering or chamfering the ring, the ring is designed to use combustion pressures to force the ring tighter against the cylinder wall and the bottom of the ring groove (Figure 13-35). The top ring provides primary sealing of the combustion pressures. The second ring is used to control the small amount of pressures that may escape past the top ring. The most common materials for constructing compression rings are steel and cast iron. The face of the ring is usually coated to aid in the wear-in process. This coating can be graphite, phosphate, iron oxide, molybdenum, or chromium. The bottom piston ring groove houses the oil control ring. There are two common styles of oil control rings: the cast-iron oil ring and the segmented oil ring. Both styles of oil rings have slots to allow the oil from the cylinder walls to pass through. The ring groove also has slots to provide a passage back to the oil sump. Many engine manufacturers now install low-tension piston rings. These rings are about as thin as an oil control ring rail. With cylinders in good condition they provide adequate combustion chamber sealing with reduced friction on the cylinder walls as the piston moves up and down. Because low-tension rings provide a reduced internal engine friction, they also provide a slight improvement in fuel economy. The downside is they are more susceptible to sticking and tension loss causing blow-by, oil consumption, and reduced compression. Segmented oil control rings have three pieces (Figure 13-36). The upper and lower portions are thin metal rails that scrape the oil. The center section of the ring is constructed of spring steel and is called the expander or spacer. The movement of the piston causes the oil ring to scrape oil from the cylinder wall and return it to the sump.

Wear-in is the required time needed for the ring to conform to the shape of the cylinder bore.

Oil control rings are piston rings that control the amount of oil on the cylinder walls.

Spacer

Cylinder wall Scrapers

Figure 13-36 Typical three-piece oil control rings with two thin scrapers with a spacer in between. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Ring Materials

Shop Manual Chapter 13, page 599

Big end refers to the end of the connecting rod that attaches to the crankshaft. Small end refers to the end of the connecting rod that accepts the piston pin.

Rings are replaced whenever the engine is disassembled for repairs. Generally, you will use original equipment rings with an engine being built to original specifications. There are times, however, when you may choose an appropriate alternative. The following ring materials and their strengths and weaknesses are discussed to assist you in ring selection. Rings have long been made from cast iron. These rings are a popular choice when overhauling an engine. The material is strong but soft. It can conform best to irregular cylinder surfaces and shapes. When re-ringing a worn engine without boring the cylinders, cast-iron rings are usually recommended. When selecting a replacement ring for a fully overhauled engine, be sure that the quality meets or exceeds the original equipment. Other rings are made of steel or coated with chrome or moly. Many late-model engines are fitted with steel top rings for their increased durability. The top ring suffers the most; it is exposed to the combustion flame and the highest pressures. If an engine is originally equipped with a steel top ring, it should be replaced with the same steel ring. Many modern turbocharged, supercharged, high-output engines, and engines with the top ring positioned very close to the piston head require steel top rings. Moly rings are cast rings with a groove cut in the face that is filled with molybdenum. Moly rings provide excellent scuff resistance and superior durability. The moly holds a little oil to lubricate the ring and reduce the friction against the wall. Moly rings are frequently used as original equipment rings. This is an excellent replacement choice for a freshly bored engine. They seal quickly against a properly finished cylinder wall. Chrome-coated rings are another popular replacement option. They are stronger and can last 50 percent longer than plain cast-iron rings. They do not resist scuffing as well as moly rings, but they also do not absorb contaminants the way moly rings can. When an engine is operated in dusty or sandy conditions, consider chrome rings. They will not seal an out-of-round cylinder, however, so they should be used only in freshly bored and properly finished cylinders. Chrome-coated rings are very hard and can cause excessive cylinder wall wear unless the block is cast with additional amounts of nickel to increase its strength and resistance to abrasives.

Oversize Rings If the cylinder bore diameter is increased to correct for wear, the piston and rings must be replaced. The piston and rings are oversize to fit the new bore diameter. Piston rings are typically available in standard, 0.020, 0.030, 0.040, and 0.060 inch oversizes. If an odd size is needed, such as 0.010 or 0.050 inch oversize, use the ring one size smaller; for example, for 0.010 inch oversize, use a standard ring; for 0.050 inch oversize, use a 0.040 inch oversize. Metric oversizes are available in 0.50, 0.75, 1.0, and 1.5 mm. You cannot install oversized piston rings with a piston of standard size. An oversized piston must accompany it.

CONNECTING RODS The connecting rod transmits the force of the combustion pressures applied to the top of the piston to the crankshaft (Figure 13-37). To provide the strength required to withstand these forces and still be light enough to prevent rough running conditions, the connecting rod is constructed from one of the following methods: 1. 2. 3. 4.

Forged from high-strength steel Made of nodular steel Made from cast iron Made of sintered powdered metal

To increase its strength, the connecting rod is constructed in the form of an I (Figure 13-38). The small bore at the upper end of the rod is fitted to the piston pin. The piston pin can be Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Piston

Pin Connecting rod

Oil lubrication of cylinder walls

Oil passage in crankshaft

Oil under pressure Free movement Rod cap

Crankshaft

Figure 13-37 The connecting rod connects the piston to the crankshaft.

Big end

I beam

Little end

Figure 13-38 A typical connecting rod.

pressed into the piston and a free fit in the connecting rod. In this type of mounting, a bushing is installed in the small rod bore. The piston pin can also be pressed into the small rod bore and a free fit in the piston. The piston moves on the pin surface without the use of bushings. The larger bore connects the rod to the crankshaft journal. The large bore is a twopiece assembly. The lower half of this assembly is called the rod cap. The rod cap and connecting rod are constructed as a unit and must remain as a matched set. During cylinder block disassembly, the connecting rods and caps should be marked to ensure proper match when installed. Most rod caps are machined from the connecting rods during the manufacturing process. Some manufacturers now use a new process of “breaking” the cap off of the connecting rod. This process uses connecting rods constructed from sintered powdered metal. The connecting rod is then shot peened to remove any flash and to increase surface hardness. After the rod bolt holes are drilled and tapped, the bolts are installed loosely. Next, the break area is laser scribed and the cap is fractured in a special fixture. This creates a rod and cap parting surface that is a perfect fit and creates a stronger joint (Figure 13-39).

Shop Manual Chapter 13, page 600

Exaggerated view of parting line detail

Figure 13-39 Fracturing, instead of machining, the connecting rod cap provides a perfect concentric fit when it is bolted back together. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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SUMMARY ■

■ ■

■ ■

Bearings are used to carry the loads created by rotational forces. Main bearings carry the load created by the movement of the crankshaft. Connecting rod bearings carry the load of the power transfer from the connecting rod to the crankshaft. Oil is supplied to the rod-bearing journals through holes in the crankshaft. Undersize bearings are used to maintain correct oil clearance when the crankshaft journal has been ground to provide a new journal surface. Oversize bearings are used if the bearing bore diameter has been increased. The piston, when assembled to the connecting rod, is designed to transmit the power produced in the combustion chamber to the crankshaft.

■

■ ■ ■

■

■

The piston is manufactured with expansion controls to provide better cylinder fit when the engine is at normal operating temperature. Pistons are generally made of aluminum; they may be cast, forged, or hypereutectic cast. The piston pin is generally offset toward the major thrust side to reduce piston slap. To seal combustion pressures, the piston is fitted with compression rings. The rings seal the piston to the cylinder wall. Cast iron, molybdenum, chrome, and steel rings may be used, depending on the engine design and cylinder condition. The connecting rod links the piston to the crankshaft; it is typically formed in I-beam construction to provide the required strength to prevent bending.

REVIEW QUESTIONS Short-Answer Essays 1. Describe the function of the engine bearings. 2. Explain the bearing characteristics, spread, and crush and why they are important. 3. Explain what problems occur when the bearing oil clearances are too large. 4. List the parts of the piston and their purpose. 5. Explain the advantages and disadvantages of cast, forged, and hypereutectic pistons. 6. Describe cam ground and tapered pistons, and explain how they enhance engine performance. 7. Explain why piston pins are offset in the pistons. 8. Describe the three rings and their purposes. 9. Explain the advantages and disadvantages of cast-iron, chrome, and moly rings. 10. Describe the design and purpose of the connecting rod.

Fill-in-the-Blanks 1. Typical bearing oil clearances on modern engines are between _______________ inch and 0.0008 inch.

2. _______________ _______________ is important for heat transfer from the bearing to the block. 3. _______________ _______________ pistons are narrower across the pin side to allow for expansion. 4. Connecting rods are generally made with an _______________ _______________ shape construction to provide adequate strength. 5. The _______________ _______________ transmits the force of the combustion pressures applied to the top of the piston to the crankshaft. 6. _______________ are used to carry the loads created by rotational forces. _______________ _______________ carry the load created by the horizontal movement of the crankshaft. 7. _______________ bearings are used to maintain correct oil clearance when the crankshaft journal has been ground to provide a new journal surface. _______________ bearings are used if the bearing bore diameter has been increased. 8. A _______________ ensures proper installation of the bearing insert in the bore. 9. Steel struts help control piston _______________. 10. Some connecting rod caps are _______________ off the connecting rod during the manufacturing process to provide an improved cap-to-rod fit.

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Pistons, Rings, Connecting Rods, and Bearings

Multiple Choice 1. Undersize bearings A. have a smaller outside diameter. B. are used when the block has been line bored. C. have a thinner lining than standard bearings. D. are used when the crankshaft has been ground. 2. When bearing oil clearances are too large A. oil pressure will be reduced. B. shims are used to take up the clearance. C. the crankshaft will bend. D. All of the above. 3. Each of the following is a common type of piston, except: A. Forged aluminum C. Cast aluminum B. Forged steel D. Hypereutectic 4. The piston pin is generally offset to A. reduce bearing knock. B. protect the piston pin from combustion forces. C. reduce piston slap. D. All of the above. 5. Engine bearings may be made with each of the following as a liner except: A. Babbitt C. Copper B. Aluminum D. Cast iron 6. Rings are being chosen for an engine. Which of the following statements is true? A. If the engine has been freshly bored, cast-iron rings will provide the longest service life. B. Moly rings should be used on slightly worn cylinders for quick wear-in. C. Chrome rings will last a long time but may wear the cylinder walls. D. Many light-duty, lower-powered engines use steel rings.

271

7. Piston head designs can A. increase the compression ratio. B. increase turbulence. C. increase emissions. D. All of the above. 8. While discussing connecting rod bearings, Technician A says that the bearing curvature is slightly greater than the curvature of the connecting rod bore. Technician B says that when half of the bearing insert is installed in the rod cap, the bearing should protrude above the cap surfaces. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. While discussing pistons, Technician A says that the larger diameter of a cam ground piston is across the piston pin bores. Technician B says that pistons are manufactured with a perfectly vertical skirt. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Common piston ring designs include A. a three-piece oil ring. B. a top compression ring with no chamfer or taper. C. a top compression ring with an expander behind the ring. D. an oil ring below the piston pin.

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CHAPTER 14

ALTERNATIVE FUEL AND ADVANCED TECHNOLOGY VEHICLES

Upon completion and review of this chapter, you should understand and be able to describe: ■

■ ■ ■ ■ ■ ■

The reasons for manufacturers’ research and development of alternate fuel and advanced technology vehicles. The common uses for alternatively fueled vehicles. The difference between dedicated and retrofitted alternate fuel vehicles. The basic operation of a propanefueled vehicle. The benefits of E85. The basic operation of a flexible fuel vehicle. The benefits and limitations of compressed natural gas as an automotive fuel.

■ ■ ■ ■

■ ■ ■

The basic operation of a CNG-fueled vehicle. The advantages and disadvantages of electric automobiles. The benefits of hybrid electric vehicles. The difference between the various hybrid electric vehicle power system layouts. The basic operation of a hybrid electric vehicle. The basic operation of the Atkinsoncycle and Miller-cycle. Some of the benefits and limitations of fuel cell vehicles.

Terms To Know Atkinson-cycle engine Closed loop system Compressed natural gas (CNG) Converter Dedicated alternative fuel vehicle Dual parallel system

E85 Flexible fuel vehicle (FFV) HD-5 LPG Inverter M85 Miller-cycle engine Open loop system

Parallel system Power splitting device Pumping losses Regenerative braking Retrofitted Series system SULEV

INTRODUCTION Automobiles contribute greatly to North America’s air pollution. In many urban areas, air pollution from vehicles is the primary source of pollution. According to the U.S. EPA, mobile sources contribute 51 percent of the carbon monoxide pollution. The governments of the United States and Canada and their respective environmental protection agencies implement legislation that requires vehicle manufacturers to continuously reduce the levels of emissions their vehicles emit. They also demand increases in fuel economy. In the United States, the Clean Air Act of 1990 produced a longrange set of milestones that require manufacturers to reach lower and lower levels of emissions with a greater percentage of their fleets. In an effort to reduce emissions, increase fuel economy, and comply with the environmental laws, manufacturers have invested millions of dollars into research and design of alternatively fueled 272

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and advanced technology vehicles. Many fleet vehicles run on propane, compressed natural gas (CNG), biodiesel, or E85. Recently, many fleets have purchased electric and plug-in hybrid vehicles. Fleets that have these vehicles are also installing charging stations. Many of these fleets use government incentives and grants to help purchase and maintain their fleets. When crude oil prices go high, more fleets and companies may choose alternative fuels for various reasons. There are several advanced technology hybrid vehicles now on the market that offer significantly reduced emissions and increased fuel economy. The engines of the alternative fuel and hybrid vehicles on the market today are still very similar to the engines we have been discussing throughout the book. Changes will be noted when appropriate. The electric motors used in hybrid vehicles and their components are an entirely different type of power source. Their operation is discussed in a general fashion in this text, and safety precautions will be offered in the Shop Manual.

ALTERNATIVE FUEL VEHICLE USE Many urban areas in the United States and in Canada have air quality that falls below safe levels on certain days or periods of the year. These areas are called nonattainment areas, meaning the quality of air regularly falls below the safe standard. Individual regulations vary by state and province, but many urban areas require that fleets run a percentage of their vehicles on alternative fuels. The Clean Air Act also introduced the Clean Fuel Fleet program in the United States. The act requires that in some nonattainment areas, certain fleets meet special fuel vehicle emissions standards. Transportation money from the federal government in the United States is also tied to a state’s actions to reduce mobile source emissions. Many municipal, government, and educational fleets run on alternate fuels. Alternative fuel vehicles may be dedicated or retrofitted. A dedicated propane vehicle, for example, is one that the manufacturer designed from the ground up to run on propane. Changes to the body, suspension, and fuel system were all designed to optimize the vehicle to run on propane. The vehicle’s oxygen sensors, catalytic converters, and powertrain control modules have all been designed to run on the alternative fuel. Many alternative fuel fleet vehicles have been retrofitted to run on an alternative fuel. This means that a particular gas vehicle was chosen and then conversions were made to allow the vehicle to run on the alternative fuel. The dedicated fuel vehicles are more efficient, but they are not always available from the manufacturer to serve the needs of the consumer.

Dedicated alternative fuel vehicles were designed to run on an alternative fuel.

A vehicle that was originally designed to run on gasoline but has been changed to run on an alternative fuel is often called retrofitted or converted.

PROPANE VEHICLES The first widely used alternative fuel vehicle has been the propane vehicle. Propane is liquefied petroleum gas (LPG) but often simply called propane or LPG. Automotive engine grade is HD-5 LPG. HD-5 consists of a minimum of 90 percent propane and a maximum of 5 percent propylene. Many fleets operate propane trucks and buses. In the United States, there are an estimated 350,000 trucks, cars, and industrial vehicles operating on propane. Propane’s popularity as an alternative fuel is growing because retrofitters are now starting to produce both throttle body and multiport injection systems. There are also retrofit kits available for diesel engines. The propane fuel is blended with the diesel fuel. Propane cannot start the engine alone, because of the high compression pressure in the engine. Therefore, the ratio of propane to diesel is lower during engine starting and continues to increase as the engine temperature rises. This continues to a point where

HD-5 LPG is a “consumergrade” propane.

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there is only enough diesel fuel being injected to cause ignition; then the propane is allowed to complete the combustion. A few manufacturers have offered dedicated propane vehicles or vehicles with factory conversion kits with modern fuel-injection systems in the past several years. Vehicles running on propane produce lower hydrocarbon (HC) and carbon monoxide (CO) emissions. The reductions can be as high as 50 to 80 percent. These vehicles also produce up to 30 percent lower oxides of nitrogen (NO x ) emissions. Propane is also a sealed system, so it has no evaporative emissions. It is a clean-burning fuel with low particulate and sulfur emissions. This makes it an attractive fuel for fleet operators in urban locations who are required to use an alternate fuel. LPG is a by-product of natural gas and crude oil refining; 65 percent of propane comes from natural gas. This is advantageous to both the United States and Canada, which have the largest stores of natural gas in the world. Natural gas is plentiful and cheaper to refine. Most propane supply companies run all their vehicles on propane. The United States has more than 10,000 refilling stations available, while Canada has about 5,000 refilling facilities. Unfortunately, fuel consumption, by volume, is slightly higher with propane than with gasoline. Propane actually has more energy available in it, but it is not as dense, so by volume it has less available energy. Because it is roughly 30 percent less dense than gasoline, it is also difficult to carry as much fuel as would be necessary to maintain the range of a gas vehicle. Propane tanks are specially made sealed units because the fuel is stored at pressures that may be over 200 psi (Figure 14-1). Propane vehicles run very similarly to gas-fueled vehicles. With a few modifications to the engine, virtually any vehicle can be converted to run on propane. Because of the size of the storage tanks, it is more common to convert trucks or larger vehicles. Vehicles can be equipped to run solely on propane or to be dual-fuel vehicles and able to run on either gasoline or propane. The tanks are fitted either in the trunk or under the vehicle (Figure 14-2). Propane is stored in the tank(s) at temperatures roughly between 1008F and 2008F (558C and 1108C). A conversion system includes a fuel controller, valves, actuators, electronics, and software modifications. The liquid fuel travels from the tank to a

Figure 14-1 Liquid propane storage tanks may be mounted under the vehicle or in the trunk. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Injector

Fuel rails

Fuel lines

Fill fitting Pressure regulator

Fill filter

Overfill prevention and stop-fill valve

Pump and filter

Figure 14-2 Fuel delivery components of the liquid propane injection system.

vaporizer/pressure regulator (also called a converter), which converts propane to a gaseous state. From the vaporizer, the fuel goes to the throttle body injector, the carburetor, or the fuel injectors for delivery to the intake manifold. There are federal, and often state and local, tax incentives for converting vehicles to cleaner burning alternative fuels that help make up the cost of conversion. Other factors include the following: ■ Original fuel economy of the vehicle ■ Number of miles traveled per year ■ Initial cost of conversion ■ Engine life expectancy Factory conversions of passenger cars and light-duty trucks can cost about $2,500 above the cost of the conventional vehicle. Aftermarket conversion kits may cost $1,500 to $3,000, depending on the amount of components needed and whether the system is an open loop system or a closed loop system. California requires warranties on conversion kit components, and Canada has regulations on component safety as well as installation and installers. Dedicated propane fuel vehicles differ very little from gas vehicles aside from the fuel tank. A pump in the tank delivers liquid fuel at the correct pressure to the fuel injectors. Unused vaporized fuel returns to the tank. A single hose with two sections is used to deliver and return fuel (Figure 14-3). When the system is a bifuel system, a fuel selector switch is used to inform the PCM which fuel is being used. The operator can change the fuel setting, or if the propane tank runs low enough, the PCM will automatically change to gasoline. This changes the fuel delivery strategy to optimize performance, emissions, and fuel economy (Figure 14-4).

An open loop system delivers fuel based on demand and has no way of detecting whether the amount sent was ideal in terms of performance, emissions, or fuel economy.

A closed loop system uses sensors (typically an oxygen sensor) that inform the PCM about the air-fuel ratio leaving the engine, so it can adjust accordingly.

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Chapter 14 Fuel rail

PCM

Injectors Return valve

Fuel selector switch

From fuel sender

Tank—150 psi (1,035 kPa) at 90°F

Supply valve

Vaporizer

Pump

Figure 14-3 A single hose performs the functions of delivery and return.

Filter

Coolant circuit

From propane fuel tank

Figure 14-4 A manual selector switch allows a change from propane to gasoline.

The engines in propane vehicles may be identical to those in gasoline engines. Using propane reduces the wear on the engine because it is a cleaner fuel and forms less carbon and corrosive acids. Some fleet operators claim that propane engines last two to three times longer than their gasoline-powered counterparts. The National Propane Gas Association claims that spark plugs last 80,000 to 100,000 miles. The same mechanical failures and maintenance procedures exist; the occurrences are often extended. E85 is an automotive fuel made of 85 percent ethanol and 15 percent petroleum. A flexible fuel vehicle (FFV) is designed to be able to run on either gasoline or a methanol or ethanol blend, M85 or E85. M85 is an automotive fuel that contains 85 percent methanol and 15 percent gasoline. It is not commonly used anymore.

E85 AND FLEXIBLE FUEL VEHICLES E85 is made from 85 percent ethanol and 15 percent petroleum. Ethanol can be made from virtually any starch feedstock such as corn, sugarcane, or wheat. Most of the U.S. production of ethanol today comes from corn. A bushel of field corn can be converted into 2.7 gallons of fuel ethanol. Some ethanol producers are reaching even greater efficiencies. E85 is a domestically renewable energy source that helps reduce dependency on imported oil. This has a positive influence on the economy. It also helps reduce tailpipe and greenhouse gas emissions (carbon dioxide). E85 has the highest oxygen content of any fuel currently available. This makes it burn much more completely and cleaner than gasoline. EPA studies have shown that high-blend ethanol fuels can reduce harmful exhaust emissions by over 50 percent. E85 also reduces carbon dioxide (CO 2 ), the emission contributing to global warming, by nearly 30 percent. Flexible fuel vehicles (FFVs) are designed to run on E85 or gasoline. M85 shares many of the attributes and benefits of E85. Older flexible fuel vehicles could run on E85, regular gasoline, or M85. M85 uses a mix of methanol and gasoline. Methanol is

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicles

sometimes used by race cars but is quickly being replaced by E85. The 2007 Indianapolis 500 race cars were all powered by ethanol. The use of M85 as an automotive fuel has decreased in popularity because of its toxicity, corrosiveness, and groundwater contamination issues. FFVs have been designed by the manufacturers to run on multiple fuels: They are not converted afterward. They typically use a fuel sensor that determines the level of alcohol in the fuel, and the PCM modifies its fuel delivery, ignition timing, and emissions strategies accordingly (Figure 14-5). The sensor can be located in the tank or in the fuel line after the tank (Figure 14-6). Instead of a special sensor, some manufacturers use wide-band oxygen sensors to determine the fuel content and adjust the fuel curve accordingly. The engine is essentially the same as a gasoline model, though different engine oil may be specified when running exclusively on E85. The fuel system components have been modified to resist the added corrosive effects of the alcohol in M85 and E85. A typical layout of an E85 vehicle is shown in Figure 14-7.

Figure 14-5 A flexible fuel sensor.

Return line Fuel tank (submerged electric fuel pump in tank)

Pressure regulator

In-line filter

Injector

Ethanol fuel sensor

Figure 14-6 This E85 flexible fuel system mounts the fuel sensor in line between the tank and the fuel rail. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 14 Special piston rings and fuel injectors

Noncorrosive fuel tank

Variable fuel sensor

Modified fuel inlet hose

Advanced electronic control system

Special catalytic converter

Stainless steel exhaust

Figure 14-7 The layout of an E85 flexible fuel vehicle.

COMPRESSED NATURAL GAS VEHICLES Compressed natural gas (CNG) is lightly refined natural gas stored under high pressure.

Compressed natural gas (CNG) is a promising alternative fuel for the future. It is a cleanburning fuel, is available in abundance domestically (both in the United States and Canada), and it is commercially available to end users at refilling stations. Natural gas is the cleanest burning fuel used today. CNG vehicles can emit 70 percent less CO, 89 percent less HC, and 87 percent less NO x . CNG vehicles also produce significantly lower (20 percent) greenhouse gas emissions. Dedicated CNG vehicles produce little or no evaporative emissions during fueling or use. This is a huge advantage over conventional gas vehicles and gas filling stations. Gas vehicle evaporative emissions and fueling contribute over 50 percent of the vehicles’ HC emissions. Natural gas is minimally refined and widely available as a resource in the United States and Canada. Prices for CNG should be low once production is increased and refueling stations are abundant. Already many CNG refilling stations are available, which is another benefit of CNG as an alternative fuel choice (Figure 14-8). CNG has an octane rating of between 110 and 130. This allows dedicated CNG vehicles to run higher compression ratios and advanced ignition timing. The potential power from a CNG vehicle is increased, even though CNG has a lower energy content than gasoline. Vehicles can be converted to CNG, or they can be dedicated CNG or bifuel vehicles. Several manufacturers produce CNG vehicles, including the following: ■ Chevrolet Cavalier ■ Dodge Caravan and B Van ■ Ford Crown Victoria and Contour ■ Select GM trucks ■ Honda Civic GX ■ Toyota Camry ■ Volvo S70 and V70 Many of these models are offered as bifuel vehicles, which can run on CNG or unleaded gasoline.

Cylinder Safety The layout of a typical CNG vehicle is shown in Figure 14-9. The CNG is stored in tanks under pressures between 3,000 and 3,600 pounds. Some of the tanks are going as high as 100 bar. These tanks are typically aluminum cylinders wrapped in fiberglass because they cost less and weigh less than comparable cylinders made of steel or composites. All tanks are sealed with epoxy paint and clear polyurethane to further protect them from environmental factors. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 14-8 A compressed natural gas filling station.

Fill valve

High-pressure lock-off (HPL)

Manual fuel shut-off valve

High-pressure regulator

CNG tank

Label Fuel-pressure sensor Coolant lines High-pressure fuel filter

Low-pressure fuel filter

Temperature sensor

Low-pressure regulator (LPR)

Low-pressure lock-off (LPL)

Figure 14-9 The layout of a CNG vehicle.

All cylinders are certified by the U.S. Department of Transportation and labeled with the psi capacity, serial number, manufacturer’s name, and date of manufacture. The U.S. DOT requires that tanks be inspected every three years. The inspection must be performed by a qualified service person in accordance with the manufacturer’s inspection process. Retest marking labels must be affixed to the tank near the original test date label and coated with epoxy. No repairs are allowed to the CNG cylinders. Cylinders must be removed from service 15 years after the date of manufacture. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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In Canada, cylinders must be inspected and also hydrostatically tested every three years, as regulated by the Canadian Standards Association. A retest label must be placed near the original label and sealed with epoxy. Repairs are not allowed, and all cylinders must be replaced 15 years after the date of manufacture. A label may be attached to the fuel filler door stating the retest and expiration date.

Vehicle Safety There are two safety devices designed to stop fuel flow if leaks or service need to be performed. The fuel control valve is a manually operated ball valve located on each tank (Figure 14-10). Full clockwise rotation turns the fuel flow off. The control valve also houses a pressure relief valve. The cylinder releases excess pressure when temperatures reach approximately 2158F (1008C). Remember, temperature increases as pressure increases. The relief valve will vent all the CNG from the cylinder. This does not pose a fire hazard, as CNG rises into the atmosphere rather than hangs at ground level like propane or gasoline. Once a relief valve has popped, it must be replaced. There is also a quarter-turn manual shut-off valve (Figure 14-11). It is accessed from the outside of the vehicle and is labeled “Manual Shut-Off Valve” on a body panel. When the valve is parallel to the line, fuel can flow. When the handle is perpendicular to the fuel line, fuel flow is stopped from the tanks to the fuel delivery system. CNG vehicles use high-pressure stainless steel seamless fuel tubes. Fittings on the high-pressure side of the system are double-ferrule, compression-type fittings made of special stainless steel (Figure 14-12). Fittings on the low-pressure side of the system use national pipe thread (NPT) and 45-degree flare fittings.

Fuel cylinder

Fuel gauge pressure sensor

Valve handle

Pressure relief safety device

Figure 14-10 A fuel control valve at the tank with a pressure relief valve.

Gas flow

No gas flow

Figure 14-11 Typical manual valve operation. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicles Double-ferrule fitting

Figure 14-12 CNG fuel line fittings.

Vehicle Operation Fuel flows through either a single dual-stage regulator or a primary and then a secondary regulator. The regulator reduces the pressure to between 90 psi and 140 psi. The regulator may contain a built-in pressure relief valve and fuel filter (Figure 14-13). The relief valve is on the low pressure side of the regulator and relieves pressure above roughly 200 psi, depending on the vehicle model. The pressure regulator has engine coolant running to it because as the pressure drops rapidly, so does the fuel temperature. The coolant prevents fuel from freezing (Figure 14-14). The PCM controls a high-pressure fuel shut-off solenoid and a low-pressure fuel solenoid. The solenoid is an on/off valve that controls fuel flow. The PCM operates a relay to turn the solenoid on and off. The PCM also uses a fuel low-pressure sensor to help with its injector timing strategy (Figure 14-15). It also uses a fuel temperature sensor as an input to help calculate fuel delivery and ignition timing. The PCM uses these sensors along with other typical engine sensors to optimize performance, emissions, and fuel economy. Refilling a CNG vehicle is done through a traditional fuel door (Figure 14-16). The connector to which you attach the quick connect fitting contains a one-way check valve (Figure 14-17). Another one-way valve is installed between the fuel fill line and the fuelpressure regulator to prevent any release of gas to the atmosphere through the filling connection. It is important to remember that most CNG vehicles are serviced at a dealership or specialized company by factory-certified and trained technicians. High-pressure fuel shut-off solenoid

Fuel filter

High-pressure fuel tube

Low-pressure fuel tube

Coolant hoses (2)

Pressure relief tube

Fuel-pressure regulator

Figure 14-13 CNG fuel-pressure regulator. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Coolant hoses (2)

Fuel-pressure regulator

Figure 14-14 Engine coolant hoses routed to the regulator prevent icing as the pressure drops at the regulator. Fuel low-pressure sensor

Fuel temperature sensor

Discharge valve

Fuel shut-off valve

Figure 14-15 The fuel low-pressure sensor and fuel temperature sensor help the PCM determine the injector on time. Check valve

Cylinder test date 2004 - 10 - 10 Year Month Day

"T" fitting Manual shut-off valve

Figure 14-17 A one-way check valve prevents fuel from escaping the system during refueling.

Fuel filler door

Fuel fill receptacle and protective cap

Figure 14-16 CNG tank filling receptacle and cylinder test date sticker. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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THE HONDA CIVIC GX CNG VEHICLE As an example of a specific dedicated CNG vehicle, we look at Honda’s Civic CNG vehicle. It was the first vehicle in the United States to meet the California Air Resources Board (CARB) “Advanced Technology Partial Zero–Emissions Vehicle” (AT-PZEV) standard. This gives users emissions credits toward highway funding and EPA regulations. It also easily meets the Super-Ultra-Low-Emission Vehicle (SULEV) standard that was required of certain vehicles in some states in 2005. Its engine is an aluminum alloy in-line four-cylinder with 1.7 L (1,590 cc) displacement. It runs a compression ratio of 12.5 to 1, and the CNG octane is rated at 130. It has an SOHC 16-valve head with variable valve timing (VTEC-E). The valves and valve seats have been modified. The pistons and connecting rods have been strengthened (Figure 14-18). It produces 98 lbs.-ft. of torque at 4,100 rpm. It is connected to a continuously variable transmission (CVT). It holds the equivalent of 7.5 to 8 gallons of gasoline and has a “real-world” driving range of 200 miles (320 km). It has a fuel economy rating of 31 mpg city and 34 mpg highway. The emissions from the vehicle are particularly impressive (Figure 14-19). The CO, NMOG (hydrocarbon), and NOx emissions compared to the Civic gasoline UltraLow-Emission Vehicle (ULEV) shows the significant reductions. The CNG Civic uses two specially coated oxygen sensors to reduce the effects of hydrogen on their operation. The catalyst system includes a close-coupled catalyst and an under-floor catalyst to reduce emissions (Figure 14-20). Fleets are widely using Honda CNG vehicles (Figure 14-21).

A SULEV vehicle produces an extremely low measurable amount of pollution from its tailpipe. This is a Federal government vehicle standard.

Piston and connecting rod Compression Ratio 12.5:1 Stronger material pistons and connecting rods

Pressure regulator Integrated type 1st stage unit 2nd stage unit

Cylinder head CNG special valves and valve seat materials

Catalyst Close-coupled under-floor converter Two oxygen sensors

Figure 14-18 Engine modifications are made to the dedicated CNG Civic. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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100%

Primary O2 sensor

ULEV standard

50% Close-coupled TWC 0% CO

NMOG

NOx Under-floor TWC

SULEV standard

100%

Secondary O2 sensor

Figure 14-20 The CNG Civic uses two catalysts and two oxygen sensors.

50%

0% CO

NMOG

NOx

Gasoline (ULEV) CNG (SULEV)

Figure 14-19 The CNG Civic easily meets the Ultra-Low-Emission Vehicle (ULEV) and Super-Ultra-Low-Emission Vehicle (SULEV) standards. It also reduces emissions dramatically compared to its very clean Civic gasoline model.

Figure 14-21 This urban cab company uses CNG vehicles in its fleet.

ELECTRIC VEHICLES Electric vehicles (EVs) are driven by an electric motor powered by batteries. General Motors introduced the EV1 electric car in 1996. Many manufacturers have produced some version of an electric vehicle in the 1990s for fleet use, in part to meet California’s regulation that a certain percentage of fleet vehicles be zero-emission vehicles (ZEV). These vehicles are ideal for urban driving where range is short. The driving range of GM’s EV1 is roughly 75 miles, depending on the type of driving. This limits the use of electric vehicles dramatically. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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A BIT OF HISTORY Electric vehicles have been around since the early 1800s, although they were relatively impractical until later in the century. They were at the peak of popularity in the United States during the early 1900s.

Battery technology has also limited the further development of electric vehicles as an alternative for the general public. The EV1 used 26 12-volt batteries to power the 102-kilowatt AC electric motor that drives the front wheels. The basic layout of the electric vehicle is shown in Figure 14-22. Fully charging a discharged set of batteries through a 220-volt outlet can take 14 hours. A Magne Charge inductive charger was developed by AC Delco to reduce the time to 3 to 4 hours. Nonetheless, until batteries that can provide longer range are developed, the production of electric vehicles for use by the general public is diminished. GM discontinued the production of the EV1 in 1999 and removed all of them from the road by 2003 because they were all originally leased. Some of the technology and experiences learned from the EV1 led to the development of today’s hybrid electric vehicles (HEV). The Chevy Volt (Figure 14-23) is considered an “extended range” EREV. The Gen 1 Volt has a battery range of between 25 and 50 miles while its total or extended range is up to 350 miles. In most circumstances it uses its 1.4-liter gasoline engine to power the generator. The engine can operate on demand under its more efficient rpm range. Under normal circumstances, the engine does not produce more energy than demanded at the time. The second generation Volt has a battery range of up to 53 miles while its total or extended range is up to 425 miles. It is more efficient using a 1.5 liter engine with direct injection and uses a wider battery charge range. GM also has the all-electric Spark Bolt EV. The Bolt EV has a 200-mile range, 200 horsepower (hp), and 266 lbs.-ft. of torque, using a lithium-ion battery. Out of the multiplatform vehicle manufactures, the Nissan Leaf has the next closest range at 100 miles per charge. The Spark EV has an 82-mile range, 140 hp, and 327 lbs.-ft. of torque. Most of the vehicle manufacturers now offer at least one full electric model vehicle. Tesla builds electric cars exclusively that have a range of 218 to 270 miles, 287 to 713 lbs.-ft. of torque and 259- to 762-motor horsepower. Electric vehicles and transport mechanisms are widely used in industrial applications, such as in warehouses, where emissions cannot be easily vented.

Battery pack

Electric motor

Transmission

Electric wires

Battery pack

Figure 14-22 The batteries supply power to the electric motor that drives the vehicle. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Electric drive unit

Engine generator

Charge port

Figure 14-23 Chevy Volt’s engine generator and battery pack layout.

HYBRID ELECTRIC VEHICLES Hybrid electric vehicles use two power sources to propel the vehicle. Versions sold in the United States and Canada use an electric motor(s) and a gas or diesel engine to reduce emissions, improve fuel economy, and in some cases, increase power. The first massproduced, commercially available hybrid vehicles were the Honda Insight and the Toyota Prius (Figure 14-24). The top three hybrid cars sold are the Toyota Prius, the Camry, and the Honda Civic. The problem of vehicle range has been eliminated, as the gas engine and brake system can be used to recharge the battery pack. The Honda Insight has a range of more than 600 miles on its full 10.6-gallon gas tank, depending on driving conditions. Tailpipe emissions are also greatly reduced; in 2008, the Toyota Prius earned the AT PZEV government emissions rating. The Toyota Prius continues to be a well-selling vehicle; as of

Figure 14-24 The Toyota Prius has become a very popular hybrid vehicle. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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April 2016, total sales of the car reached over 5.6 million. Many people believe that until fuel cell and hydrogen-powered vehicles become a mass-produced affordable reality, HEVs will have a significant impact on market product and emissions.

AUTHOR’S NOTE I see more and more HEVs commuting on the road with me as I regularly drive to work. Friends report that they are very pleased with the performance of their Prius and the Honda Civic hybrids. I drove a Prius for work for a few years. I found it to be easy to operate and work on, plus it fit my family in there. A few of the owners with these cars have, however, complained of lower fuel mileage than the posted estimates. These fuel economy ratings are provided by the Environmental Protection Agency, not the vehicle manufacturer. Most vehicles achieve lower actual fuel economy than the posted rating. I found that there is a wide gap in the fuel economy, and it is based on driving habits and patterns. On some days the Prius I drove could get up to 65 mpg average with easy driving and slow acceleration. On other days when I was in heavy highway commuter traffic and harder acceleration, it would go down to 40 mpg. Another consideration is that HEVs are designed to get better fuel economy during city driving, when the electric motor gets more use, than during extended travel on the highway.

HEV OPERATION The vehicle is powered by either the electric motor, the engine, or in some cases, both. An HEV system can be characterized as a series system, a parallel system, or a dual parallel system. In a series system, just one of the power sources can be used to drive the vehicle. The electric motor drives the vehicle, while the gasoline or diesel engine powers a generator that charges the batteries to power the motor. A parallel system, which most current models employ, can use the power of both the electric motor and the engine simultaneously to propel the vehicle. The parallel system is named as such because both power sources can apply torque to move the vehicle. The electric motor can also act in reverse, as a generator to recharge the batteries. A parallel system can also use either the electric motor or the engine exclusively to power the vehicle (Figure 14-25). A system is called dual parallel when it has two electric motors and one engine, all of which can drive the vehicle at the same time. This is employed on pickup and sport utility vehicles to date. An AC electric motor is typically used to start the vehicle from a stop. Electric motors generate maximum torque at 0 rpm, so acceleration is acceptable even when a smaller gas engine is used. The electric motor is charged by a battery pack. During light acceleration or cruise, the electric motor may work alone to power the vehicle. On some vehicles when power is in high demand, both the electric motor and the gasoline engine are used to maximize performance. During moderate acceleration, the gasoline engine may run alone to provide the torque and horsepower required at higher speeds. The engine may also run without the electric motor when the batteries need to be charged. The gasoline engine powers the generator to charge the batteries while it is running. When the vehicle comes to a stop, both the gas engine and the electric motors are turned off to reduce emissions and consumption to zero. At the instant the throttle is pressed, the electric motor begins to spin and accelerate the vehicle. Some trucks and SUVs using a dual parallel hybrid electric vehicle have a traction motor at each axle to retain the four-wheel-drive capacity (Figure 14-26). Some vehicles also employ regenerative braking. On these systems, the kinetic energy typically wasted during braking is converted into electrical energy to recharge the batteries. It also helps stop the vehicle, as a noticeable drag is felt while the vehicle momentum turns the motor or generator to charge the batteries.

A series system HEV uses the electric motor to drive the vehicle; the gas motor recharges the batteries to power the electric motor.

A parallel system HEV can use the electric motor and the engine to power the vehicle. It can also use just one power source at a time.

In a dual parallel system HEV, two electric motors and an engine are used to drive the vehicle.

Regenerative braking uses the lost kinetic energy during braking to help recharge the batteries.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Stator assembly

Rotor assembly

Figure 14-25 The motor is used to generate electricity as well as drive the vehicle. A rotor and stator are also used in a traditional generator.

Motor controllers and power inverters Diesel or gas combustion engine Traction motor and transaxle Electrical storage

Traction motor and transaxle

Figure 14-26 This dual parallel hybrid has a traction motor at each axle to drive the vehicle, plus a traditional gas engine.

On vehicles that use the gasoline motor and regenerative braking to recharge the batteries, external charging is never needed. This makes these vehicles much more appealing to the consumer. The consumer only needs to fill up the gas tank, like any traditional vehicle owner.

Batteries The batteries currently being used or in prototype are our familiar lead-acid batteries, nickel-metal hydride (NiMH) batteries, and lithium-ion batteries. Each of these batteries has advantages and disadvantages over the other. Considerations for use include longevity, recharging ability, weight, and cost. The battery packs must be maintained at a relatively constant temperature, so they require a heating and cooling system (Figure 14-27). Manufacturers estimate that battery packs may need to be replaced after 10 years of use. The current price of a battery pack runs between $1,800 and $3,000. Some of the other electronic components can cost several thousand dollars; an inverter for a new Prius is close to $5,000. Manufacturers are offering excellent warranty programs for their batteries and hybrid components to keep the new technology popular and customers satisfied. Battery packs and HEV electronic components are generally warrantied for 10 years.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Voltages on hybrid vehicles can run up to 500 volts, so a technician must thoroughly understand the safety precautions before servicing the hybrid vehicle.

Electric Motors Modern HEVs typically use one or more alternating current (AC) permanent magnet (PM) motors to drive the vehicle. The operation of the motor is similar in theory to that of the operation of the permanent magnet starter motors used on many of today’s vehicles (Figure 14-28). As a matter of fact, one of the electric motors may be used to start the engine and take the place of a traditional starter. The HEV motors use high AC voltage to deliver the high-power demands of moving the vehicle. They may also be called traction motors. The motor shown in Figure 14-29 is mounted between the engine and transmission on the flywheel. The starting system of a hybrid electric vehicle is different from the normal starting system. The high-voltage battery pack is typically used to start the gasoline engine. The same set of electric motors that are used for propulsion are used in conjunction with a gear set to start the gasoline engine. An HEV’s main computer will start the engine when the conditions are met. These conditions may be low voltage on the HEV battery pack, A/C demand, electrical demand, or acceleration demand. The starters on some modern gas and diesel engines are controlled by the computer, similar to an HEV. Special care must be taken when servicing these vehicles.

Other Hybrid Technology Components A power splitting device is used to change the power from one source to the other and to combine the forces of both when necessary (Figure 14-30). A planetary gear set may be used to allow the electric motor to drive one member and the gasoline motor to drive another (Figure 14-31). Some HEVs use a continuously variable transmission (CVT) that houses some of the components and performs some of the functions of the power splitting device. An inverter is used to convert the DC voltage stored by the battery pack to the AC voltage required by the electric motors. A converter is used to change the high-voltage battery output of 270 to 500 volts down to 12 volts, which can be used by the conventional electrical system. In most cases, there is no longer a traditional 12-volt generator because the battery pack can supply plenty of power for the vehicle accessories. Heating and cooling system

A power splitting device changes the mode of power delivery from one source to the other or to a combination of both sources.

A converter is used to change the very high battery pack voltage to 12 volts for the conventional electrical system.

An inverter is used to convert DC volts to AC volts.

Housing

Battery pack Electrical connectors Cooling connections

Fuse Drive motor controller

Battery pack controller Rotor

Figure 14-27 A typical 360-volt battery pack layout with a heating and cooling system.

Magnets

Housing

Stator

Figure 14-28 The components of a permanent magnet motor. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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3-phase power cable connections Electric motor/ generator

Combustion engine

Fuel tank Electrical storage

Stator

Figure 14-30 The power splitting device allows the vehicle to run on a combination of power sources or either one individually.

Sun gear Connects to generator

Ring gear connects to motor and differential

Rotor

Figure 14-29 A flywheel-mounted PM motor. Planetary carrier Connects to the engine

Planetary gears Connect to planetary carrier

Figure 14-31 A planetary gear set uses different gear combinations to distribute power from the motor and engine.

Gasoline Engine The gasoline engine used in an HEV may be the same as the one used in the traditional variant of the model or it may be specially fitted to be optimized for hybrid use (Figure 14-32). The changes to the gasoline engine are minimal in terms of operation and diagnosis. Many of the HEV gasoline engines are newer technology engines and employ variable valve timing and some changes to the intake system.

Atkinson-Cycle Engine The Atkinson-cycle engine holds the intake valve open longer during the compression stroke to increase fuel economy.

The Atkinson-cycle engine is a common gasoline internal combustion engine design used in some HEVs such as the Toyota Prius, Chevrolet Tahoe, Toyota Camry, and Ford Escape/Mercury Mariner. The Atkinson-cycle engine has a lower power output when compared to similar displacement Otto-cycle engines but also has increased efficiency. Originally, the Atkinson-cycle engine had a connecting link attached to the crankshaft that allowed all four cycles of a four-stroke cycle to occur in one crankshaft revolution. Today’s Atkinson-cycle engines in HEVs refer to the principles of the cycles and the ratios, rather than having an additional linkage on the crankshaft. The Atkinson-cycle engine actually sacrifices a little bit of power but gains 7 to 10 percent fuel mileage and further reduces emissions. Engines lose power as they try to pump the piston up against pressurized air during the compression stroke. These are

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Figure 14-32 This Honda Civic Hybrid uses a 1.3-L engine in its Integrated Motor Assist system.

the pumping losses that the Atkinson-cycle engine reduces. The Atkinson-cycle allows the intake valve to be open longer during the compression stroke. This action allows for more air to be pushed back into the intake manifold and less compression to occur. During the power stroke, the volume of air that was in the compression stroke has to expand to a volume that is greater. This event leads to an increase in the heat energy that is converted to mechanical energy. The mechanical efficiency of the engine is now higher, at the expense of the lower-power density of the charge during the power stroke. This event makes the volumetric ratio of the compression stroke to the power stroke less than 1:1. The intake camshaft lobe is modified in an Atkinson-cycle engine to hold the intake valve open longer (Figure 14-33).

Pumping losses are wasted power from the pistons pushing up against compressed air during the compression stroke.

2 1

Figure 14-33 Lobe No. 1 shows the Atkinson style camshaft, compared to the traditional lobes shown in No. 2. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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The Miller-cycle engine is similar to the Atkinsoncycle engine, but it holds the intake valve open for a longer time. This requires it to be accompanied by a supercharger; otherwise it would be a very low-power engine.

Miller-Cycle Engine The Miller-cycle engine is a modification of the four-stroke cycle engine. A few manufacturers are producing prototype HEV vehicles that use a Miller-cycle gas engine. Some vehicles such as the Mazda Millennia are powered by a Miller-cycle engine. In this type of engine, a supercharger supplies highly compressed air through an intercooler into the combustion cylinders. The intake valves remain open longer compared to a conventional four-stroke cycle engine. This action prevents the upward piston movement from compressing the airfuel mixture in the cylinder until the piston has moved one-fifth of the way upward on the compression stroke. The later valve closing allows the supercharger to force more air into the cylinder. The shorter compression stroke lowers cylinder temperatures and still gets the same (or more) compression as a standard Otto four-stroke design because the Miller design uses a supercharger to increase compression. Normally, without a supercharger, holding the intake valve open for a longer duration would result in a loss of compression and power. This operation makes the compression stroke less of a consumer of the total engine power. By delaying the start of the compression stroke, the engine is not wasting energy by pushing the piston up on the compression stroke. As compression builds in the cylinder, the energy needed to turn the crankshaft and move the piston increases. This energy would normally be delivered by the crankshaft, which is powered by the other cylinders in the engine that are on the power stroke. Allowing for this delay to occur also allows for the crankshaft to be in a more mechanically advantageous position (past BDC). The greater volume of air in the cylinder creates a longer combustion time, which maintains downward pressure on the piston for a longer time on the power stroke. This action increases engine torque and efficiency. The Miller-cycle principle allows an engine to produce a high horsepower and torque rating for the displacement of the engine. The Miller-cycle engine is similar to a modern Atkinson-cycle engine, except the Miller-cycle engines have a supercharger associated with their incoming air charge. The greater volume of air in the cylinder creates a longer combustion time, which maintains downward pressure on the piston for a longer time on the power stroke. This action increases engine torque and efficiency. The Miller-cycle principle allows an engine to produce a high horsepower and torque for the CID of the engine.

Toyota Prius HEV With more than 5 million on the road, Toyota is on its fourth-generation Toyota Prius. Its Hybrid Synergy Drive system is a very popular vehicle in many parts of North America (Figure 14-34). The Prius is a true hybrid, engineered from the ground up as an HEV. The newest Gen 4 uses a 1.8-L inline four-cylinder 13:1 compression Atkinson-cycle engine. Its DOHC cylinder head is fitted with 16 valves and variable valve timing, VVT-i. The engine itself delivers 95 hp at 5,000 rpm and 105 lbs.-ft. of torque at 3,600 rpm. The 600-volt/71 hp permanent magnet drive motor delivers 120 lbs.-ft. of torque. The estimated total horsepower available from the power plant is 121 hp. While less torque and horsepower than the third generation, its performance is comparable due to increased efficiency. Acceleration is from 0 mph to 60 mph (0–100 km/h) in just under 10 seconds. Some of its increased efficiency is due to a cooled exhaust gas recirculation system. Its drag coefficient is one of the lowest in the industry, helping contribute to its awarded midsize car fuel economy rating of 52 mpg combined city/highway. The fuel tank holds 11.3 gallons (43 L) and has a range of approximately 600 miles (1,000 km). The batteries never need external charging and do not have a facility for it. The Prius is also the best vehicle on the North American market in terms of emissions performance. The vehicle is classified as a SULEV vehicle and meets CARB’s AT-PZEV rating. It is rated as one of the cleanest production cars on earth, producing 90 percent fewer emissions than the traditional conventional internal combustion engine. Toyota has increased production for worldwide sales from one vehicle every 8 to 10 minutes to one vehicle per minute. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 14-34 Under the hood of the Toyota Prius hybrid electric vehicle, second generation. Note the orange high-voltage cables.

The Prius is coupled to an Electronically Controlled Continuously Variable Transmission (ECCVT). A small joystick mounted on the dash controls shifting. It also has a power split device within the transmission to allow the vehicle to run on either the electric motor or the gasoline engine exclusively. One of the motors (also called generators or MG1 and MG2) works as a starter and a generator, eliminating those traditional components (Figure 14-35). Vehicle acceleration is provided by “drive-by-wire” technology. Gasoline engine Generator Power split device

Inverter HV battery

Hybrid transaxle

Reduction gears

Electric motor

Final drive

Figure 14-35 The layout of the Toyota Prius power system. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 14-36 The dashboard information offers the driver an opportunity to drive with fuel economy in mind.

Three throttle pedal position sensors inform the powertrain management system about the requested power, and depending on other inputs from the engine and motor circuitry, the electronic control units respond with acceleration from an appropriate power source. The throttle plate on the gasoline engine is driven by an electric motor to the degree requested by the control module. Braking is also managed in a similar manner. The regenerative braking system captures about 30 percent of the energy normally lost in traditional braking systems. The Prius gas engine stops when the vehicle is at a stop or at very low speeds. This further reduces fuel consumption. It is started automatically by the powertrain management system when accelerator input and other inputs indicate the need. The battery pack is a NiMH comprised of 168 1.2-volt DC cells connected in series. Twenty-eight of these modules connected in series give the Prius motors their nominal operating voltage of 201 volts (600-volt maximum) and reduce the weight of the previous battery packs used. A 56-cell lithium-ion battery pack is an available upgrade. The Prius is equipped with a dashboard that displays available battery power, instantaneous fuel economy, and a mileage bar for each 5-minute segment of driving (Figure 14-36).

PLUG-IN HYBRID ELECTRIC VEHICLES The Toyota Prius is also available as a Plug-In Hybrid Electric Vehicle (PHEV). This means that the high-voltage battery pack can be charged up at home and is designed to allow the vehicle to be driven for a longer period on just electricity (battery power only—engine off ). After the battery charge goes down to a certain point, the vehicle operates as a normal HEV Prius. This effectively raises the fuel economy of the vehicle by allowing it to travel farther on the same amount of gasoline. There is a trade-off by not figuring in the cost of electricity to charge up the battery pack. In some areas of the country electricity can be expensive. The Chevy Volt is another example of a PHEV. Chevrolet’s car, however, acts more like an electric car and the internal combustion engine acts more like a generator.

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FUEL CELL VEHICLES Today, there are three fuel cell electric vehicles (FCEVs) available to drive in the United States or, more specifically, in the state of California: the Honda FCX Clarity, the Hyundai Tucson Fuel Cell, and the Toyota Mirai. Except for the Toyota Mirai, they can only be leased, not purchased. Many experts believe, however, that the fuel cell will eventually become the primary power plant for the modern automobile or at least capture the advanced technology market. Many manufacturers have prototype fuel cell vehicles. An FCEV is an electric car: the battery pack is charged by the hydrogen fuel cell. The reality of mass-marketed fuel cell vehicles may be at least a decade off, however, while research and development into hydrogen conversion, fuel cell technology, and refilling infrastructure concerns are resolved. Interest and research investment is high because hydrogen is a regenerative fuel and its use could drastically reduce our consumption of nonrenewable fuel sources. A fuel cell vehicle operates very much like an electric vehicle except that hydrogen (or another type of fuel cell) supplies electrical power to the motor(s) rather than batteries. Fuel cells electrochemically combine oxygen (from the air) and hydrogen to produce electricity. A special membrane is used to allow interaction between hydrogen and oxygen. Hydrogen will normally “explode” when introduced into the atmosphere with any electrical charge in it. Safety issues related to using hydrogen as a fuel have slowed development of the hydrogen fuel cell vehicle. Obviously, all development will place safety as the foremost issue, considering hydrogen’s potential hazards. Many other fuels are being considered to power fuel cells. Hydrogen is at the forefront because it can be regenerated, but methanol, ethanol, and gasoline are also being tested. A reformer can be used to separate the hydrogen out of the fuels, and the hydrogen feeds the fuel cell. The fuel cell produces electricity to run the electric motor that powers the vehicle. Additionally, solid fuel cells are being researched.

SUMMARY ■

■ ■ ■ ■ ■ ■ ■ ■ ■

Federal and provincial regulations are driving manufacturers to develop more fuel-efficient, environmentally friendly vehicles. Automobile sources are a primary source of air pollution. Many areas of North America have air quality that at times is below the safe standard. Alternate fuel and hybrid electric vehicles can produce fewer emissions. Vehicles can be designed to run on alternative fuels or retrofitted to run on alternate fuels. Many fleet vehicles choose to run on alternative fuels. Propane vehicles produce lower HC and CO emissions. E85 is a renewable fuel source that could reduce dependence on imported oil. Flexible fuel vehicles can run on E85, gasoline, or a combination of both. Natural gas is a plentiful resource in North America.

■ ■ ■ ■ ■ ■ ■ ■ ■

CNG vehicles store their fuel in tanks under pressures between 3,000 psi and 3,600 psi. CNG vehicles reduce emissions and can run higher compression ratios. CNG tank inspections are regulated by the U.S. and Canadian governments to ensure safety. Electric vehicles produce zero emissions but have a short driving range between recharging. HEVs use an electric motor and a gasoline or alternate fuel engine to power the vehicle. HEVs can dramatically increase fuel economy and decrease emissions. HEVs offer adequate power and excellent range between fill-ups. No external battery recharging is required on modern HEVs. FCEVs may be the next big development in reducing vehicle emissions and increasing fuel economy.

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REVIEW QUESTIONS Short-Answer Essays 1. Describe the reasons that manufacturers are looking for ways to reduce emissions and fuel consumption. 2. Explain the difference between a dedicated and a retrofitted alternate fuel vehicle. 3. Explain two benefits of propane as an alternative fuel. 4. What are the benefits of E85 as an automotive fuel? 5. What are some of the added or changed components on a flexible fuel vehicle? 6. Explain the basic fuel system of a CNG vehicle. 7. List three safety precautions incorporated into CNG vehicles. 8. What are the emission reduction percentages when using CNG as a fuel? 9. Describe the power flows in a parallel system HEV. 10. Explain the basic operation of a typical parallel system HEV from a stop sign to full acceleration.

Fill-in-the-Blanks 1. The _______________ _______________ _______________ of 1990 produced regulations in the United States that required manufacturers to produce vehicles with lower and lower emissions. 2. _______________ is a mix of ethanol and petroleum. 3. A _______________ alternative fuel vehicle has been originally designed to run on the designated fuel. 4. CNG is typically stored at pressures between _______________ and _______________. 5. AT-PZEV stands for _______________ _______________ ________________ ________________. 6. The Honda Civic CNG vehicle engine has a compression ratio of _______________:1.

7. A system that uses the wasted kinetic energy from braking is called a _______________ _______________ system. 8. An HEV that uses a gasoline engine strictly to power an electric motor is a _______________ system HEV. 9. The Atkinson-cycle engine increases fuel economy by reducing the engine’s _______________ _______________. 10. The second-generation Toyota Prius can accelerate from 0 mph to 60 mph (0–100 km/h) in roughly _______________ seconds.

Multiple Choice 1. According to the U.S. EPA, mobile sources contribute roughly _______________ percent of the carbon monoxide emissions to the air pollution problem. A. 10 C. 50 B. 25 D. 75 2. When a conversion is made to a gas vehicle to allow it to run on an alternative fuel, it is called a _______________ vehicle. A. HEV C. Flexible fuel B. Dedicated D. Retrofitted 3. When discussing propane, which statement is true? A. Propane is denser than gasoline. B. Propane has more available energy. C. Propane is stored at 2,000 psi. D. Propane has lower fuel consumption than gasoline. 4. When running a vehicle on propane, engine wear is greatly reduced because A. propane is a cleaner fuel. B. the engine runs on higher compression pressures. C. it produces lower HC emissions. D. the engine runs on higher fuel pressures. 5. E85 is typically made from all of the following, except: A. Corn C. Sugarcane B. Wheat D. Peanuts

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6. The “greenhouse gas” that contributes to global warming is A. CO. C. HC. B. CO 2. D. NO x . 7. Flexible fuel vehicles use a fuel sensor that detects _______________ so the PCM can better calculate spark timing and fuel delivery. A. Fuel temperature C. Alcohol content B. Fuel density D. Oxygen content 8. The use of CNG vehicles would reduce _______________ emissions more than the use of any other alternate fuel or HEV other than the electric vehicle. A. HC C. NO x D. CO 2 B. CO

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9. Natural gas has an octane rating of A. 60–80. C. 110–130. B. 80–105. D. 120–150. 10. Technician A says that an HEV uses a smaller gas engine than the conventional model vehicle. Technician B says that some parallel HEVs can use the electric motor(s) to boost the power of the gasoline engine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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GLOSSARY

Note: Terms are highlighted in bold, followed by Spanish translation in color. Advanced camshaft An advanced camshaft has the intake valve open more than the exhaust valve at TDC. It is used to improve low speed torque. Árbol de levas de avance Un árbol de levas de avance tiene la válvula de admisión más abierta que la válvula de escape cuando se encuentra en el punto muerto superior. Se utiliza para mejorar el momento de torsión a baja velocidad. Aerobic sealants Aerobic-type liquid gasket maker cures in the presence of oxygen to form a seal between two parts. Obturadores aeróbicos Los obturadores aeróbicos requieren la presencia de oxígeno para secarse. Air filter The air filter prevents dirt from entering the engine. Filtro de aire El filtro de aire impide el ingreso de suciedad al motor. Airflow restriction indicator An airflow restriction indicator is a meter that shows the amount of air flow past a port. This gives the technician an indicator that the air filter may be not flowing as well as it could because it is dirty. Indicador de restricción de flujo de aire El indicador de restricción de flujo de aire es un medidor que muestra la cantidad de aire que fluye a través de un puerto. Este dato le indica al técnico que la circulación a través del filtro de aire podría no ser óptima por la presencia de suciedad en el filtro. Alloys Alloys are mixtures of two or more metals. For example, brass is an alloy of copper and zinc. Aleaciones Las aleaciones son combinaciones de dos o más metales. Por ejemplo, el latón es una aleación de cobre y cinc. Anaerobic sealants Anaerobic liquid gasket maker cures in the absence of oxygen to form a seal between two parts. Obturadores anaeróbicos Los obturadores anaeróbicos solamente se secan en ausencia de oxígeno. Annealing A heat-treatment process used to reduce metal hardness or brittleness, relieve stresses, improve machinability, or facilitate cold working of the metal. Esmaltación La esmaltación es un proceso de tratamiento por calor para reducir el peligro que los metales se pongan duros o agrios, relevar las tensiones, mejorar el torneo, o facilitar el trabajo en frío del metal. Armature The movable component of the motor that consists of a conductor wound around a laminated iron core and is used to create a magnetic field. Armadura La armadura es un componente movible del motor que consiste en un conductor enredado alrededor de un núcleo de hierro la-minado y se usa para crear un campo magnético. Atkinson-cycle engine Holds the intake valve open longer during the compression stroke to reduce pumping losses. Motor de ciclo Atkinson Mantiene la válvula de admisión abierta por más tiempo durante la carrera de compresión para reducir las pérdidas de bombeo.

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Autoignition temperature The minimum temperature required to ignite a gas in air without a spark or flame to assist. Temperatura de autoencendido La temperatura de autoencendido es la temperatura mínima necesaria para que un gas arda en contacto con el aire sin la ayuda de una chispa o una llama. Back pressure Back pressure reduces an engine’s volumetric efficiency. Contrapresión La contrapresión reduce el rendimiento volumétrico de un motor. Balance shaft A shaft driven by the crankshaft that is designed to reduce engine vibrations. Eje de balance El eje de balance es un eje accionado por el cigüeñal que está diseñado para reducir las vibraciones del motor. Battery terminals Battery terminals provide a means of connecting the battery plates to the vehicle’s electrical system. Bornes de la batería Los bornes de la batería proporcionan una manera de conectar las placas de la batería al sistema eléctrico del vehículo. Bearing crush Refers to the extension of the bearing half beyond the seat. Aplastamiento del cojinete El término aplastamiento del cojinete hace referencia a la extensión del cojinete que sobresale sobre una mitad del asiento. Bearing inserts Bearing inserts are soft-faced bearings used to protect the crankshaft main and rod journals as well as the camshaft journals. Insertos de casquillos Los insertos de casquillos son casquillos de cara lisa que se usan para proteger los gorrones principales y los de bielas del cigüeñal, como también los gorrones del árbol de levas. Bearing spread Bearing spread means the distance across the outside parting edges is larger than the diameter of the bore. Extensión del cojinete El término extensión del cojinete implica que la distancia entre los bordes exteriores es mayor que el diámetro del calibre. Bedplate The bedplate is the lower part of a two-piece engine block. The bedplate may also be called the main girdle. Placa de asiento La placa de asiento es la parte inferior de un bloque de motor de dos piezas. También se la denomina bancada. Blow-by Refers to compression pressures that escape past the piston. Fuga de gases El término fuga de gases, o blowby, hace referencia a las presiones de compresión que escapan a través del pistón. Body control module (BCM) A computer used to control many systems, such as the instrument panel, radio, interior lighting, climate control, and driver information.

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Glossary Módulo de control de la carrocería El módulo de control de la carrocería (BCM, por sus siglas en inglés) es una computadora que se utiliza para controlar numerosos sistemas, como el tablero de instrumentos, la radio, la iluminación interior, el control climático y la información para el conductor. Bolt diameter Bolt diameter indicates the diameter of an imaginary line running through the center of the bolt threaded area. Diámetro del tornillo El diámetro del tornillo indica el diámetro de una línea imaginaria que atraviesa el centro del área enroscada del tornillo. Bolt length Bolt length indicates the distance from the underside of the bolt head to the tip of the bolt threaded end. Longitud del tornillo La longitud del tornillo indica la distancia de la parte de abajo de la cabeza del tornillo hasta la punta del enroscado del tornillo. Bore A bore is the diameter of a hole. Calibre El calibre es el diámetro de un orificio. Bottom dead center (BDC) A term used to indicate that the piston is at the very bottom of its stroke. Punto muerto inferior El punto muerto inferior (BDC, por sus siglas en inglés) es un término utilizado para indicar que el pistón se encuentra en la posición más baja de su carrera. Brake horsepower The usable power produced by an engine. It is measured on a dynamometer using a brake to load the engine. Caballos de fuerza del freno Los caballos de fuerza del freno es la potencia de uso que produce un motor. Se mide sobre un dinamómetro usando un freno para cargar el motor. Burn time The amount of time from the instant the mixture is ignited until the combustion is complete. Tiempo de combustión El tiempo de combustión es el período que transcurre desde el instante en que la mezcla comienza a arder hasta que se completa la combustión. Burned valves Valves that have warped and melted, leaving a groove across the valve head. Válvulas quemadas Las válvulas quemadas son válvulas que se han deformado y fundido y, como consecuencia, presentan una ranura en la cabeza de la válvula. Cam ground pistons A piston is not a perfect circle shape, it is more of an oval shape. Cam ground pistons are oval shaped so that they can expand to a more perfect circle shape when heated. Pistón fresado excéntricamente Un pistón no tiene una forma circular perfecta, sino que es un poco ovalado. Los pistones fresados excéntricamente tienen una forma ovalada que les permite expandirse y adquirir una forma circular más perfecta al calentarse. Cam-phasing Another term used for variable valve timing. Ajuste de fase de leva Otro término utilizado para el ajuste de válvula variable. Camshaft A shaft with eccentrically shaped lobes on it to force the opening of the valves. Árbol de levas El árbol de levas es un eje que posee lóbulos montados excéntricamente para forzar la apertura de las válvulas. Camshaft bearings Camshaft bearings are required in most engines as a means of reducing friction between the camshaft and the cylinder block. Cojinetes del árbol de levas En la mayoría de los motores, los cojinetes del árbol de levas son necesarios para reducir la fricción entre el árbol de levas y el bloque de cilindros.

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Camshaft lift Camshaft lift is the valve lifter movement created by the rotating action of the camshaft lobe. Typical lobe lift of original equipment in the block camshafts is between 0.240 in. and 0.280 in. (6 mm and 6.6 mm). Elevación del árbol de levas La elevación del árbol de levas es el movimiento de la carrera de la válvula que crea la acción giratoria del lóbulo del árbol de levas. La elevación típica del lóbulo del equipo original en los árboles de levas de garrucha está entre 6 y 6.6 mm (0.240 y 0.280 pulg.). Cam-shifting Sometimes called cam-switching, provides the ability for the valves to open different amounts for increased engine power and fuel economy. Desplazamiento de leva Conocido algunas veces como cambio de leva, permite regular la apertura de las válvulas para aumentar la potencia del motor y el ahorro de combustible. Carbon steel Steel with a specific carbon content. Acero semiduro El acero semiduro tiene un contenido específi co de carbono. Case hardening A heating and cooling process for hardening metal. Because the case hardening is only on the surface of the component, it is usually removed during machining procedures performed at the time the engine is being rebuilt. It is not necessary to replace the case hardening in most applications. Cimentación en caja La cimentación en caja es un proceso de calentamiento y enfriamiento para carburar o cimentar el metal. Ya que la cimentación en caja sólo es en la superfi cie del componente, generalmente se quita durante las gamas de mecanizado que se realizan al tiempo que se reconstruye el motor. No es necesario reemplazar la cimentación en caja en la mayoría de las aplicaciones. Catalytic converter A catalytic converter reduces tailpipe emissions of carbon monoxide, unburned hydrocarbons, and nitrogen oxides. Convertidor catalítico Un convertidor catalítico reduce las emisiones de monóxido de carbono del tubo de escape, hidrocarburos sin quemar y óxidos de nitrógeno. C-class oil The C stands for compression ignition. In some areas the C stands for commercial engines. C-class oil is designed for commercial or diesel engines. Aceite clase C El aceite clase C está diseñado para motores diésel o comerciales. La letra C proviene del inglés “compression ignition”, encendido por compresión. En el caso del aceite clase S, la letra S proviene del inglés “spark ignition”, encendido por chispa. No obstante, en algunos lugares la S representa el término en inglés “service engines”, motores de servicio, y la C, “commercial engines”, motores comerciales. Ceramics A combination of nonmetallic powdered materials fired in special kilns. The end product is a new product. Cerámica La cerámica es una combinación de materiales no metálicos pulverizados que se cuecen en hornos especiales. El resultado de este proceso es un nuevo producto final. Cetane number The cetane number of a fuel is the measurement of how easily a diesel fuel can be ignited. Número de cetano El número de cetano, o cetanaje, de un combustible indica la facilidad de encendido de un combustible diésel. Chamber-in-piston A piston with a dish or depression in the top of the piston.

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Pistón en cámara Un pistón en cámara es un pistón con un disco o depresión en la parte superior del pistón. Channeling Channeling is referred to as local leakage caused by extreme temperatures developing at isolated locations on the valve face and head. Canalización La canalización es una fuga local provocada por el desarrollo de temperaturas extremas en puntos aislados en la cabeza y la cara de la válvula. Clearance ramp The area of the mechanical lifter camshaft from base circle to the edge comprises the clearance ramp. Rampa de desahogo El área de la elevación mecánica del árbol de levas desde el círculo base hasta la orilla incluyen la rampa de desahogo. Closed loop system A closed loop system uses sensors (typically an oxygen sensor) that inform the PCM about the air-fuel ratio, allowing the engine to adjust accordingly. Sistema de circuito cerrado Un sistema de circuito cerrado utiliza sensores (típicamente un sensor de oxígeno) que informa al MCM sobre la relación combustible aire, dejando al motor para que pueda ajustarse en onsecuencia. CNC A CNC machine uses special computer software to machine close tolerances. CNC Un equipo CNC emplea un software especial para mecanizar tolerancias estrechas (rigurosas). Coil An electrical device that converts low voltage from the battery into a very high voltage that is able to push a spark across the gap of the spark plug. Bobina La bobina es un dispositivo eléctrico que convierte el bajo voltaje de la batería a un muy alto voltaje que puede empujar una chispa a través del huelgo de la bujía. Coke Coke is a very hot-burning fuel formed when coal is heated in the absence of air. Coal becomes coke at temperatures above 1022°F(550°C). It is produced in special coke furnaces. Coque El coque es un combustible de alta temperatura que se forma al calentar carbón en ausencia de aire. El carbón se convierte en coque a temperaturas superiores a los 1022° F(550°C). Se produce en hornos especiales para coque. Combustion Combustion is the controlled burn created by the spark igniting the hot, compressed air-fuel mixture in the combustion chamber. Combustión La combustión es el proceso de quemado controlado que se produce cuando una chispa enciende la mezcla caliente y comprimida de aire y combustible en la cámara de combustión. Combustion chamber The combustion chamber is a sealed area in the engine where the burning (combustion) of the air and fuel mixture takes place. Cámara de combustión La cámara de combustión es una zona sellada del motor donde se quema la mezcla de aire y combustible. Composites Composites are human-made materials using two or more different components tightly bound together. The result is a material that has characteristics that neither component possesses on its own. Compuestos Los compuestos son materiales artificiales formados por dos o más componentes estrechamente unidos. El resultado es un material con características propias que no están presentes en ninguno de los componentes. Compressed natural gas (CNG) Lightly refined natural gas stored under high pressure.

Gas natural comprimido El gas natural comprimido (GNC o CNG, por sus siglas en inglés) es un gas natural ligeramente refinado que se almacena a alta presión. Compression-ignition (CI) engines A Compression-ignition (CI) engine ignites the air-fuel mixture in the cylinders from the heat of compression (this engine is often fueled by diesel fuel). Motores de encendido por compresión Un motor de encendido por compresión (CI, por sus siglas en inglés) enciende la mezcla de aire y combustible en los cilindros con el calor de la compresión (estos motores a menudo utilizan combustible diésel). Compression ratio The compression ratio is a comparison between the volume above the piston at BDC and the volume above the piston at TDC. Compression ratio is the measure used to indicate the amount the piston compresses each intake charge. Índice de compresión El índice de compresión es la relación entre el volumen que queda por encima del pistón cuando se halla en el punto muerto inferior y el volumen que queda por encima del pistón cuando se halla en el punto muerto superior. El índice de compresión es la medida utilizada para indicar la compresión del pistón en cada carga de admisión. Compressions rings Compressions rings are the top rings in a piston assembly that provide cylinder sealing during the compression and power strokes. Anillos de compresión Los anillos de compresión son los anillos superiores del conjunto del pistón, que permiten sellar los cilindros durante las carreras de compresión y de potencia. Compressor wheel A compressor wheel is a vaned wheel mounted on the turbocharger shaft that forces air into the intake manifold. Rueda compresora Una rueda compresora es un difusor de paletas montado en un eje turboalimentador que fuerza aire dentro del colector de entrada. Connecting rod bearing journals Connecting rod bearing journals are offset from the crankshaft centerline to provide leverage for the piston to turn the crankshaft. Muñones de los cojinetes de la biela Los muñones de los cojinetes de la biela están desplazados con respecto a la línea central del cigüeñal para accionar el pistón a fin de que haga girar el cigüeñal. Connecting rod bearings Connecting rod bearings are inserttype bearings retained in the connecting rod and mounted between the large connecting rod bore and the crankshaft journal. Cojinetes de la biela Los cojinetes de la biela son cojinetes tipo encarte que se retienen en la biela y se montan entre el orifi cio grande de la biela y el gorrón del cigüeñal. Connecting rods The connecting rod forms a link between the piston and the crankshaft. Bielas La biela establece una unión entre el pistón y el cigüeñal. Converter A converter is used to change the very high battery pack voltage to 12 volts for the conventional electrical system. Convertidor El convertidor se utiliza para cambiar el voltaje elevado del paquete de baterías a los 12 voltios del sistema eléctrico convencional. Coolant recovery system The coolant recovery system prevents loss of coolant if the engine overheats, and it keeps air from entering the system.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Glossary Sistema de recobro de refrigerante El sistema de recobro de refrige-rante previene la pérdida de fl uido refrigerador si se sobrecalienta el motor, y no permite que entre aire al sistema. Cooling system A cooling system controls the temperature of an engine by allowing it to heat up quickly, operate at the correct temperature, and remove excess heat. Sistema de enfriamiento El sistema de enfriamiento controla la temperatura del motor, ya que le permite calentarse rápidamente, funcionar a la temperatura adecuada y eliminar el exceso de calor. Core engine A used engine that is disassembled for purposes of rebuilding in large volumes. Motor reconstruible Un motor reconstruible es un motor usado que se desmonta para su reconstrucción. Core plugs Core plugs are used to seal the holes machined into the block to remove the sand after casting. Core plugs are often called freeze plugs. Occasionally, when coolant is not adequately protected with antifreeze, it freezes in the block; a core plug will pop out and prevent the block from cracking. People are not always that lucky, however, and that is not the purpose of core plugs. Tapones del núcleo Los tapones del núcleo se utilizan para sellar los orificios rectificados en el bloque a fin de quitar la arena que queda después de la fundición. Los tapones del núcleo a menudo se denominan tapones o sellos del bloque del motor. A veces, cuando el refrigerante no se protege adecuadamente con un anticongelante, se congela en el bloque. En tal caso, a veces un tapón del núcleo salta para impedir que el bloque se fisure. No todos son tan afortunados y, además, ese no es el propósito de los tapones del núcleo. Crankshaft A crankshaft is a shaft held in the engine block that converts the linear and reciprocating motion of the pistons into a nonreversing rotary motion used to turn the transmission. The crankshaft rotates in only one direction. It is not reversible. Cigüeñal El cigüeñal es un eje presente en el bloque del motor que convierte el movimiento lineal recíproco de los pistones en un movimiento de rotación no reversible que se utiliza para hacer girar la transmisión. El cigüeñal gira solamente en una dirección. No se puede revertir. Crankshaft counterweights Crankshaft counterweights are positioned opposite the connecting rod journals and balance the crankshaft. Contrapesos del cigüeñal Los contrapesos del cigüeñal se colocan opuestos a los gorrones de la biela y balancean el cigüeñal. Crankshaft throw Crankshaft throw is the measured distance between the centerline of the rod journal and the centerline of the crankshaft main journal. Crankshaft throw multiplied by two equals the piston stroke. Codo del cigüeñal El codo del cigüeñal es la distancia entre la línea central del muñón de la biela y la línea central del muñón principal del cigüeñal. La medida del codo del cigüeñal multiplicada por dos equivale a la carrera del pistón. Crate engine A crate engine is a new or remanufactured engine that is built with fresh components, such as bearings, rings, and lifters. You can purchase crate engines with or without cylinder heads. Motor en enrejado Un motor en enrejado es un motor Nuevo o refabricado que está construido con nuevos componentes, tales como cojinetes, anillos y taqués. Cycle A cycle is a complete sequence of events. Ciclo Un ciclo es una secuencia completa de eventos.

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Cylinder An engine cylinder is a round hole bored into the cylinder block. Cilindro Un cilindro de motor es un orificio redondo taladrado en el bloque de cilindros. Cylinder block The main structure of the engine. Most of the other engine components are attached to the block. Bloque de cilindros El bloque de cilindros es la estructura principal del motor. Casi todos los demás componentes del motor están conectados al bloque. Cylinder head A large object that houses most of the valvetrain and covers the combustion chamber. Culata del cilindro La culata del cilindro es el componente de gran tamaño que aloja la mayor parte del tren de válvulas y cubre la cámara de combustión. Dedicated alternative fuel vehicles Dedicated alternative fuel vehicles were designed to run on alternative fuel. Vehículos de combustible alternativo dedicado Los vehículos de combustible alternativo dedicado están diseñados para funcionar con combustibles alternativos. Detergents Gasoline additives that clean the fuel system. Detergentes Los detergentes son aditivos que limpian el sistema de combustible. Detonation Detonation is different from preignition. It is characterized as abnormal combustion. Detonation occurs when pressure and temperature build in gas chambers outside of the normal spark flame. This may be caused by improper octane, high engine loads, or improper combustion. Detonation is often known as “spark knock” or “pinging.” Detonación La detonación es diferente del preencendido. Se caracteriza por una combustión anormal. La detonación se produce cuando en las cámaras de combustión se acumulan presión y temperatura más allá de la chispa normal. Esto puede deberse a un octanaje erróneo, a una carga elevada del motor o a una combustión incorrecta. La detonación a menudo se denomina “pistoneo”, “golpeteo” o “pinging ”. Diesel Any fuel that will operate in a diesel (compression ignition) engine. It is named after its inventor, Rudolf Diesel. Diesel fuel has a lower volatility rating than gasoline. It can be derived from petroleum or alternative sources such as bio-mass, natural gas, or soy beans. Diésel Se denomina combustible diésel a cualquier combustible que funcione en un motor diésel (encendido por compresión). Lleva el nombre de su inventor, Rudolf Diesel. El combustible diésel tiene un índice de volatilidad menor que la gasolina. Puede ser derivado del petróleo o de fuentes alternativas, como la biomasa, el gas natural o la soja. Differential The differential allows the wheels to turn at different speeds as the vehicle turns corners. It is internal to a transaxle and external to a transmission. Diferencial El diferencial permite que las ruedas giren a velocidades diferentes cuando el vehículo gira en una esquina. Es interno para el transeje y externo para la transmisión. Displacement Displacement is the measure of engine volume. The larger the displacement, the greater the power output. Desplazamiento El desplazamiento es la medida del volumen del motor. A mayor desplazamiento, mayor potencia de salida. Distributor The distributor is usually driven by the camshaft. It uses the timing of the valves to control the timing of the spark ignition.

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Distribuidor El distribuidor generalmente es accionado por el árbol de levas. Utiliza la sincronización de las válvulas para controlar la sincronización del encendido por chispa. Distributor ignition (DI) A distributor ignition (DI) system has a distributor that distributes spark to each spark plug. Encendido con distribuidor Un sistema de encendido con distribuidor (DI, por sus siglas en inglés) posee un distribuidor que suministra la chispa a cada bujía. Dual overhead cam (DOHC) A dual overhead cam (DOHC) engine has two camshafts mounted above each cylinder head. Leva de disco superior dual El motor de leva de disco superior dual tiene dos árboles de levas montados sobre cada cabeza del cilindro. Dual parallel system In a dual parallel system HEV, two electric motors and an engine are used to drive the vehicle. Sistema doble paralelo Los vehículos híbridos eléctricos con sistema doble paralelo se impulsan con dos motores eléctricos y un motor de combustión interna. Duration Camshaft duration is the amount of time the camshaft holds the valve open. It is measured in degrees of crankshaft rotation. Duración La duración del árbol de levas es la cantidad de tiempo durante el cual el árbol de levas mantiene la válvula abierta. Se mide en grados de rotación del cigüeñal. E85 E85 is an automotive fuel made of 85 percent ethanol and 15 percent petroleum. E85 El E85 es un combustible para automóviles hecho con 85 por ciento de etanol y 15 por ciento de petróleo. Eddy currents An eddy is a current that runs against the main current. Corrientes de Foucault Una corriente de Foucault, o corriente torbellino, es una corriente que se opone a la corriente principal. Efficiency A measure of a device’s ability to convert energy into work. Eficiencia La eficiencia es una medida de la capacidad que tiene un dispositivo para convertir la energía en trabajo. Electrolysis The chemical and electrical process of decomposition that occurs when two dissimilar metals are joined in the presence of moisture. The lesser of the two metals is eaten away. Electrólisis La electrólisis es el proceso electroquímico de descomposición que tiene lugar cuando se unen dos metales diferentes en presencia de humedad. El menor de los metales se consume. Electronic ignition (EI) An electronic ignition system uses an electronic module to turn the coils on and off. Encendido electrónico Un sistema de encendido electrónico usa un modulo electrónico para encender y apagar las bobinas. Emission control system The emission control system includes various devices connected to the engine or exhaust system to reduce harmful emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). Sistema de control de emisiones El sistema de control de emisiones incluye varios dispositivos conectados al motor o al sistema de escape para reducir las emisiones dañinas e hidrocarburos (HC), monóxido de carbono (CO) y óxidos de nitrógeno (NOx). End gases Unburned gases are called end gases. Gases finales Los gases que no se queman se denominan gases finales.

Engine An engine is defined as a device or machine that converts thermal energy into mechanical energy. Motor Un motor se define como un dispositivo o máquina que convierte energía térmica en energía mecánica. Engine bearings Engine bearings are two bearing halves that form a circle to fit around the crankshaft journals. Cojinetes de eje motor Los cojinetes de eje motor son dos mitades de cojinete que forman un círculo para ajustarse alrededor de los gorrones del cigüeñal. Engine block The engine block is the main structure of the engine that forms the combustion chamber and houses the pistons, crankshaft, and connecting rods. Bloque del motor El bloque del motor es la estructura principal del motor que conforma la cámara de combustión y aloja los pistones, el cigüeñal y las bielas. Engine cradle The engine cradle, which may also be called the suspension cradle, is the front frame member(s) in a unibody design. The engine is mounted to this frame, as is the suspension. Soporte del motor El soporte del motor, al que también se le llama soporte de la suspensión neumática, es el miembro(s) del bastidor delantero en un diseño de una sola carrocería. El motor está montado en su lojamiento, tomo también la suspensión. Engine mount An engine mount attaches the engine to the chassis and absorbs the engine vibrations. Bancada del motor La bancada del motor se sujeta del motor al chasis y absorbe las vibraciones del motor. Ethanol Ethanol is an alcohol that can be used as an automotive fuel. Etanol El etanol es un alcohol que puede emplearse como combustible para automóviles. Exhaust manifold The exhaust manifold is an exhaust collector that is mounted onto the cylinder head. Múltiple de escape El múltiple de escape es un colector de gases de escape que está montado sobre la culata del cilindro. Face The face is the tapered part of the section of the valve head that makes contact with the valve seat. Cara La cara es la parte mecanizada de la sección de la cabeza de la válvula que hace contacto con el asiento de la válvula. Ferrous metals Ferrous metals contain iron. Cast iron and steel are examples of ferrous metals. These metals are easy to identify because they will naturally attract a magnet. Metales ferrosos Los metales ferrosos contienen hierro. El hierro fundido y el acero son metales ferrosos. Estos metales son fáciles de identificar porque atraen naturalmente a los imanes. Fillet The fillet is the curved area between the stem and the head. Filete El filete es el área redondeada entre el vástago y la cabeza. Fire ring A fire ring is a metal ring surrounding the cylinder opening in a head gasket. Anillo de encendido Un anillo de encendido es un anillo metálico circuncidante a la abertura del cilindro en la guarnición de la cabeza. Flexible fuel vehicle A flexible fuel vehicle is designed to be able to run on either gasoline or a methanol or ethanol blend, M85 or E85. Vehículo de combustible flexible Un vehículo de combustible fl exible está diseñado para poder correr ya sea con gasolina o con una mezcla de metanol o de etanol, M85 o E85.

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Glossary Flexplate A flexplate is a lighter version of a flywheel and is bolted to the torque converter of an automatic transmission. Plato flexible Un plato flexible es una versión más liviana del volante. Se atornilla al convertidor de torsión de las transmisiones automáticas. Flywheel A heavy disk mounted at the end of the crankshaft to make the engine power pulses and vibrations more stable. It has a smooth surface to which the clutch assembly of a manual transmission is attached. This smooth surface is similar to the surface of a brake rotor. Volante El volante es un disco pesado que se monta en el extremo del cigüeñal para hacer más estables las vibraciones y los impulsos de potencia del motor. Tiene una superficie lisa a la cual se conecta el conjunto de embrague de las transmisiones manuales. Esta superficie es similar a la de un disco de freno. Free-wheeling engine In a free-wheeling engine, valve lift and angle prevent valve-to-piston contact if the timing belt or chain breaks. In an interference engine, if the timing belt or chain breaks or is out of phase, the valves will contact the pistons. Motor de rueda libre En un motor de rueda libre, la elevación y el ángulo de la válvula impiden el contacto de la válvula con el pistón si se averían la cadena o la correa de distribución. Si se averían o se desfasan la cadena o la correa de distribución en un motor de interferencia, las válvulas entran en contacto con los pistones. Friction The resistance to motion when one object moves across another object. Friction generates heat and is an excellent method of controlling mechanical action. Fricción La fricción es la resistencia al movimiento que se produce cuando un objeto se mueve en contacto con otro. La fricción genera calor y es una manera excelente de controlar la acción mecánica. Front main seal A lip-type seal that prevents leaks between the timing gear cover and the front of the crankshaft. Sello principal delantero Un sello principal delantero es una junta redonda de tipo escarpia de vía que previene las fugas entre la cubierta del engranaje de distribución y el frente del cigüeñal. Fuel injection Fuel injection systems use the PCM to control electromechanical devices, fuel injectors that deliver a closely controlled amount of fuel to the cylinders. Por inyección Los sistemas por inyección usan el MCM para controlar los dispositivos electromecánicos, los inyectores que mandan una cantidad de combustible muy controlada a los cilindros. Fuel system The fuel system includes the intake system that is used to bring air into the engine and the components used to deliver the fuel to the engine. Sistema de combustible El sistema de combustible consiste en el sistema de admisión que se utiliza para introducir aire al motor y los componentes empleados para suministrar combustible al motor. Full-filtration system A full-filtration system means all of the oil is filtered before it enters the oil galleries. Sistema de fi ltración máxima Un sistema de fi ltración maxima signifi ca que todo el aceite ese fi ltra antes de entrar a las galeras de aceite. Gaskets Gaskets are used to prevent engine fluids or pressure from leaking between two stationary parts. Juntas Las juntas o empaques se utilizan para impedir la fuga de fluidos o presión del motor entre dos piezas fijas.

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Gasoline Gasoline has many ingredients and compounds. It is refined from crude oil and is the most common fuel used in today’s engines. Gasolina La gasolina consta de numerosos ingredientes y compuestos. Es un producto refinado a partir del petróleo crudo y es el combustible más utilizado en los motores actuales. Glow plugs Glow plugs are threaded into the combustion chamber and use electrical current to heat the intake air on diesel engines. Bujías incandescentes Las bujías incandescentes se encuentran roscadas en la cámara de combustión y utilizan corriente eléctrica para calentar el aire de admisión en los motores diésel. Grade The grade of a bolt is the classification of its strength. Calificación La calificación de un tornillo es la clasificación de su resistencia. Grade marks Grade marks are radial lines on the bolt head. Marcas de grado Las marcas de grado son líneas radiales situadas en la cabeza del tornillo. Gray cast iron A type of cast iron that has a graphitic microstructure. It is a widely used material because of its tensile strength to weight ratio. It is a common consideration for engines because of their high strength and low weight requirements. Hierro fundido gris El hierro fundido gris es un tipo de hierro que tiene microestructura graf ítica. Es un material muy utilizado por la relación entre resistencia a la tracción y peso. Se lo tiene en cuenta para los motores porque estos requieren alta resistencia y bajo peso. Gross horsepower The the maximum power that an engine can develop. It is measured without additional accessories installed (such as belt-driven items and the transmission). Potencia bruta La potencia bruta es la máxima potencia que puede desarrollar un motor. Se mide sin accesorios adicionales (como los elementos accionados por correas o la transmisión). Harmonic balancers Harmonic balancers are used to control and compensate for torsional vibrations. Equilibradores armónicos Los equilibradores armónicos se utilizan para controlar y compensar las vibraciones torsionales. HD-5 LPG HD-5 LPG is a “consumer grade” propane. Gas licuado de petróleo HD-5 El gas licuado de petróleo (LPG, por sus siglas en inglés) HD-5 es un gas propano “para consumo”. Head The enlarged part of the valve. Cabeza La cabeza es la parte agrandada de la válvula. Head gasket The head gasket is used to prevent compression pressures, gases, and fluids from leaking. It is located on the connection between the cylinder head and the engine block. Junta de culata La junta de culata se utiliza para evitar la fuga de fluidos, gases y presiones de compresión. Está ubicada en la conexión entre la culata del cilindro y el bloque del motor. Heater core The heater core dissipates heat like a radiator. The radiated heat is used to warm the passenger compartment. Núcleo calentador El núcleo calentador disipa el calor como un radiador. El calor del radiador se usa para calentar el compartimiento del pasajero. Hemispherical chamber The term hemi may be used for an engine with hemispherical combustion chambers. Cámara hemisférica El término “hemi” se puede aplicar a un motor con cámaras de combustión hemisféricas.

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Glossary

Honing Honing a cylinder is a machining process that prepares the surface for the installation of new piston rings. Rectificado El rectificado de un cilindro es un proceso de maquinado que prepara la superficie para la instalación de nuevos aros o anillos de pistón. Horsepower A measure of the rate of work. Potencia La potencia es una medida de la tasa de trabajo. Hybrid electric vehicle (HEV) A hybrid electric vehicle (HEV) uses an electric motor in combination with a gas, diesel, or alternate fuel engine to power the vehicle. Vehículo híbrido eléctrico Los vehículos híbridos eléctricos se impulsan con un motor eléctrico junto con un motor a gasolina, diésel o combustible alternativo. Ignition system The delivery of the spark used to ignite the compressed air-fuel mixture is the function of the ignition system. Sistema de encendido La función del sistema de encendido es suministrar una chispa para encender la mezcla comprimida de aire y combustible. Indicated horsepower The amount of horsepower the engine can theoretically produce. Potencia disponible La potencia disponible es la cantidad de caballos de fuerza que teóricamente puede producir el motor. Inlet check valve The inlet check valve keeps the oil filter filled at all times, so when the engine is started, an instantaneous supply of oil is available. Válvula de retención La válvula de retención mantiene el filtro de aceite lleno en todo momento, de manera que cuando se ponga en marcha el motor, exista un suministro instantáneo de aceite. Intake air temperature (IAT) sensor The intake air temperature sensor sends an analog voltage signal to the PCM in relation to air intake temperature. Sensor de la temperatura del aire de entrada El sensor de la temperatura del aire de entrada envía una señal e voltaje análogo al MCM en relación con la temperatura de entrada. Intake manifold The intake manifold connects the air inlet tubes to the cylinder head ports to equally distribute air to each cylinder. Múltiple de admisión El múltiple de admisión conecta los tubos de admisión de aire con los puertos de las culatas de los cilindros para suministrar aire a cada cilindro de manera equitativa. Intake manifold gasket The intake manifold gasket fits between the manifold and the cylinder head to seal the air-fuel mixture or intake air. Junta del múltiple de admisión La junta del múltiple de admisión se encuentra entre el múltiple y la culata del cilindro, y sirve para sellar la mezcla de aire y combustible o el aire de entrada. Integral valve seats Integral valve seats are part of the cylinder head. Asiento de válvula integral El asiento de válvula integral forma parte de la culata del cilindro. Intercooler The intercooler cools the intake air temperature to increase the density of the air entering the cylinders. It is also referred to as a charge air cooler. Refrigerador El refrigerador disminuye la temperatura del aire de entrada para aumentar la densidad del aire que ingresa a los cilindros. También se lo denomina enfriador de aire cargado o intercambiador de calor.

Interference engine When a timing belt or chain breaks, the pistons and crankshaft will quickly stop moving, but the valvetrain will stop moving almost immediately. If an engine is designed so that the valves could possibly touch the piston when this happens (because a valve is fully open and the piston is at TDC), it is called an interference engine. Motor de interferencia Cuando se averían la cadena o la correa de distribución, los pistones y el cigüeñal dejan de moverse rápidamente, pero el tren de válvulas se detiene casi de inmediato. Si el motor está diseñado para que las válvulas puedan llegar a tocar el pistón cuando esto ocurre (porque la válvula está totalmente abierta y el pistón se encuentra en el punto muerto superior), se lo denomina motor de interferencia. Internal combustion engine Internal combustion engines burn their fuels within the engine. The power that is used as a result of burning that fuel is also developed inside the engine. In comparison, in an external combustion engine the burning of fuel occurs in an external source, or tank. The heat is then transferred to a separate component where it can be used to power the engine and move parts. Examples of external combustion engines would be steam locomotives and the Stirling engine. Motor de combustión interna Los motores de combustión interna queman combustibles dentro del motor. La potencia que se utiliza como resultado de esa combustión también se desarrolla dentro del motor. Por el contrario, en los motores de combustión externa, el combustible se quema en una fuente externa (o tanque). Luego el calor se transfiere a otro componente donde se puede utilizar para accionar el motor y mover las piezas. Algunos ejemplos de motores de combustión externa son las locomotoras a vapor y el motor Stirling. Inverter An inverter is used to convert DC volts to AC volts. Invertidor Un invertidor permite convertir los voltios de CC en voltios de CA. Journals Main journals are round machined portions on the centerline of the crankshaft where the crankshaft is held in the main bore. Muñones Los muñones principales son partes redondeadas rectificadas ubicadas en la línea central del cigüeñal, donde se mantiene el cigüeñal en el calibre principal. Kinetic energy The amount of energy that is currently being used or is currently working. Energía cinética La energía cinética es la cantidad de energía que se está utilizando o se encuentra en acción en un momento determinado. Knock sensor A knock sensor is used to detect abnormal combustion. Its data is used by the PCM to change the ignition timing. Sensor de golpeteo El sensor de golpeteo se utiliza para detectar la combustión anormal. El módulo de control del tren de potencia utiliza estos datos para cambiar la sincronización del encendido. Law of conservation of energy A principal law of physics that states that the total energy of an isolated system remains constant despite any internal changes. Ley de conservación de la energía La ley de conservación de la energía es un principio de la Física que establece que la energía total de un sistema aislado permanece constante independientemente de los cambios internos que se produzcan.

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Glossary Lifters Lifters are mechanical (solid) or hydraulic connections between the camshaft and the valves. Alzaválvulas Los alzaválvulas son conexiones mecánicas (sólidas) o hidráulicas entre el árbol de levas y las válvulas. Lip seals Lip seals are formed from synthetic rubber and have a slight raise (lip) that is the actual sealing point. The lip provides a positive seal while allowing for some lateral movement of the shaft. Sellos con reborde Los sellos con reborde están fabricados de caucho sintético y tienen un pequeño reborde o labio, que es el punto real de sellado. El reborde proporciona un sello positivo y, al mismo tiempo, permite cierto movimiento lateral del eje. Lobes The lobes of the camshaft push the valves open as the camshaft is rotated. Lóbulos Los lóbulos del árbol de levas van abriendo las válvulas a medida que el árbol de levas gira. Lobe separation angle The lobe separation angle is the average of the intake and exhaust lobe centers. It defines the amount of valve overlap. The tighter the angle (lower number of degrees), the more overlap the camshaft provides. Ángulo de separación del lóbulo El ángulo de separación del lóbulo es el promedio de los centros de los lóbulos de entrada y de escape. Se defi ne como la cantidad de superposición de la válvula. Entre más cerrado el ángulo (menor número de grados), mayor superposición proporcionará el árbol de levas. Locating tab The locating tab is a tab sticking out of bearing inserts that fits in a groove in the block, main bearing cap, connecting rod, or connecting rod cap to prevent insert rotation. Aleta de posicionamiento La aleta de posicionamiento es una aleta que sale de los insertos del cojinete que cabe en una ranura del bloque, la tapa del cojinete principal, la biela o la tapa de la biela para prevenir que gire el inserto. Long block A long block is an engine block with the cylinder head(s) and other components mounted. Bloque largo Un bloque largo en un bloque motor con las cabezas del cilindro y otros componentes montados. Longitudinally mounted engine A longitudinally mounted engine is placed in the vehicle lengthwise, usually front to rear. Motor montado longitudinalmente Un motor montado longitudinalmente se coloca a lo largo del vehículo, generalmente del frente a la parte posterior. Lubrication system The engine’s lubrication system supplies oil to high-friction and high-wear locations. Sistema de lubricación El sistema de lubricación del motor suministra aceite a las áreas de gran fricción y desgaste. M85 M85 is an automotive fuel that contains 85 percent methanol and 15 percent gasoline. It is not commonly used anymore. M85 El M85 es un combustible para automóviles que contiene un 85 por ciento de metanol y un 15 por ciento de gasolina. Ya no es de uso habitual. Main-bearing journals Main-bearing journals are machined along the centerline of the crankshaft and support the weight and forces applied to the crankshaft. Muñón del cojinete principal Los muñones de los cojinetes principales están ubicados a lo largo de la línea central del cigüeñal y soportan el peso y las fuerzas que se aplican al cigüeñal. Main bore The main bore is a straight hole drilled through the block to support the crankshaft.

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Agujero principal El agujero principal es un hoyo derecho taladrado a través del bloque para apoyar el cigüeñal. Main caps The main caps form the other half of the main bore and bolt onto the block to form round holes for the crankshaft bearings and journals. Tapas principales Las tapas principales forman la otra mitad del agujero principal y se sujetan con tornillos al bloque para formar agujeros redondos en los gorrones y en los cojinetes del cigüeñal. Major thrust surface The skirt that pushes against the cylinder wall during the power stroke is the major thrust surface. Superficie de empuje principal La superficie de empuje principal es la falda que empuja contra la pared del cilindro durante la carrera de potencia. Margin The margin is the material between the valve face and the valve head. Margen El margen es el material entre la cara de la válvula y la cabeza de la válvula. Mass airflow (MAF) sensor The mass airflow (MAF) sensor measures the mass of airflow entering the engine and sends an input to the PCM reflecting this value. This is a primary input for the PCM’s control of fuel delivery. Sensor de flujo de la masa de aire El sensor de flujo de la masa de aire (MAF, por sus siglas en inglés) mide la masa de aire que ingresa al motor y envía una entrada que refleja este valor al módulo de control del tren de potencia (PCM, por sus siglas en inglés). Se trata de una entrada primordial para el control de suministro de combustible del PCM. Mechanical efficiency The mechanical efficiency of an engine is the comparison between actual power measured at the crankshaft and the actual power developed within the cylinders. There will always be frictional losses in the crankshaft, cylinders, and connecting rods. Rendimiento mecánico El rendimiento mecánico de un motor es la relación entre la fuerza real medida en el cigüeñal y la fuerza real desarrollada en los cilindros. Siempre existen pérdidas por fricción en el cigüeñal, los cilindros y las bielas. Metallurgy The science of extracting metals from their ores and refining them for various uses. Metalurgia La metalurgia es la ciencia de extraer metales de sus minerales y refi narlos para sus varios usos. Micron A micron is a thousandth of a millimeter or about 0.0008 inch. Micrón Un micrón es una milésima de milímetro o aproximadamente 0,0008 pulgadas. Mid-mounted engine A mid-mounted engine is located between the rear of the passenger compartment and the rear suspension. It may also be called a mid-engine. Motor central Un motor central se localiza entre la parte posterior del compartimiento de pasajeros y la suspensión posterior. También se le llama motor de en medio. Miller-cycle engine Holds the intake valve open even longer during the compression stroke than the Atkinson-cycle design requiring an even higher pressure in the intake manifold which is provide by a supercharger. Motor de ciclo Miller Mantiene abierta la válvula de admisión aún más tiempo durante la carrera de compresión que en el diseño de ciclo Atkinson, para lo cual requiere una presión todavía mayor en el múltiple de admisión, la que es proporcionada por un supercargador.

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Glossary

Minor thrust surface The skirt that pushes against the cylinder wall during the compression stroke is the minor thrust surface. Superficie de empuje secundaria La superficie de empuje secundaria es la falda que empuja contra la pared del cilindro durante la carrera de compresión. Misfire A misfire means that combustion either is incomplete or does not occur at all. Fallo de encendido Un fallo de encendido signifi ca que la combustión fue incompleta o no sucedió del todo. Motor Octane Number (MON) RON and MON are octane testing numbers that are averaged together to get the advertised octane number. Each uses a different test procedure that represents different real-world driving situations. Número de octanos del motor El número de octanos de carretera y el número de octanos del motor (RON y MON respectivamente, por sus siglas en inglés) representan números obtenidos en pruebas de octanaje que se promedian para obtener el número de octanos publicado. Cada uno utiliza un procedimiento de prueba diferente que representa diferentes condiciones de conducción reales. Muffler A device mounted in the exhaust system behind the catalytic converter that reduces engine noise. Mofl e El mofl e es un dispositivo montado en el sistema de escape atrás del convertidor catalítico que reduce el ruido del motor. Multi-point fuel injection Multi-point fuel injection systems use one injector for each cylinder to deliver fuel. Inyección de combustible multipunto Los sistemas de inyección de combustible multipunto utilizan un inyector para suministrar combustible a cada cilindro. Net horsepower The amount of horsepower an engine has when it is installed in the vehicle. Potencia neta La potencia neta es la potencia que posee un motor cuando se instala en el vehículo. Nodular iron Nodular iron, also known as ductile iron, is a version of gray cast iron but is more flexible and elastic. Hierro nodular El hierro nodular, también llamado hierro dúctil, es una variedad de hierro fundido gris más flexible y elástica. Nonferrous metals Nonferrous metals contain no iron. Aluminum, magnesium, and titanium are examples of nonferrous metals. These metals will not attract a magnet. Metales no ferrosos Los metales no ferrosos no contienen hierro. El aluminio, el magnesio y el titanio son ejemplos de metales no ferrosos. Estos metales no atraerán un imán. Nucleate boiling The process of maintaining the overall temperature of a coolant to a level below its boiling point, but allowing the portions of the coolant actually contacting the surfaces (the nuclei) to boil into a gas. Ebullición nucleada La ebullición nucleada es el proceso de mantener la temperatura general de un refrigerante en un nivel inferior al punto de ebullición, pero permitiendo que las porciones de refrigerante que están en contacto con las superficies (los núcleos) se evaporen. Octane The octane number is the ratio of two test fuels that match the knock characteristic of the test fuel. The advertised octane number at a gas station is an average from RON and MON and is an indicator of the fuel’s anti-knock quality. Lower octane fuels will burn faster. Higher octane fuels will burn slower.

Octano El número de octanos es una relación entre dos combustibles de ensayo que se ajusta a la característica de golpeteo del combustible de ensayo. El número de octanos publicado en las estaciones de gasolina es un promedio entre los números RON y MON, e indica la cualidad de resistencia al golpeteo del combustible. Los combustibles de menor octanaje se queman más rápido. Los combustibles de mayor octanaje se queman más lento. Octane rating The octane rating of a fuel describes its ability to resist detonation (also known as spark knock). Octanaje El octanaje de un combustible representa su capacidad antidetonante (o de evitar el pistoneo del motor). Off set pin An off set pin is a piston pin that is not mounted on the vertical center of the piston. Garrucha de desvío Una garrucha de desvío es una garrucha de pistón que no está montada en el centro vertical del pistón. Off-square Off-square seating or tipping refers to the seat and valve stem not being properly aligned. This condition causes the valve stem to flex as the valve face is forced into the seat by spring and combustion pressures. Fuera de escuadra El término inclinación o asiento fuera de escuadra significa que el asiento y el vástago de la válvula no están alineados correctamente. Esta situación hace que el vástago de la válvula se arquee cuando las presiones de la combustión y el muelle empujan la cara de la válvula contra el asiento. Oil breakdown All oils will break down their additives over time. Oil breakdown usually refers to the results from prolonged high temperatures and pressures that quickly degrade the oil and do not allow it to perform its duties. Descomposición del aceite Con el paso del tiempo, en todos los aceites se van separando los aditivos. La descomposición del aceite suele ser resultado de una exposición prolongada a temperaturas y presiones elevadas que degradan el aceite rápidamente y no permiten que cumpla su función. Oil coking Oil coking occurs after the engine is shut down and the turbocharger is still spinning. The oil is no longer circulating, and what remains inside the turbo can literally bake into a white, hard, caked restriction in the lines. Allowing the engine to idle for a minute before shutting the engine off allows the turbo compressor to wind down and prevents this. Carbonización del aceite La carbonización del aceite se produce cuando se apaga el motor y el turbo sobrealimentador sigue girando. El aceite deja de circular y lo que queda dentro del turbo literalmente puede transformarse en una sustancia blanca y dura que obstruye las tuberías. Al dejar que el motor marche en vacío durante un minuto antes de apagarlo, el turbocompresor puede detenerse poco a poco y evitar este problema. Oil control rings The piston rings that control the amount of oil on the cylinder walls. Anillos de control del aceite Los anillos de control del aceite son ani-llos de pistón que controlan la cantidad de aceite en las paredes del cilindro. Oil cooler A heat exchanger that looks much like a small radiator. Refrigerador del aceite El refrigerador del aceite es un intercambiador de calor que se parece mucho a un radiador pequeño. Oil galleries Drilled passages throughout the engine that carry oil to key areas needing lubrication. Canales de aceite Los canales de aceite son conductos perforados en el motor que llevan el aceite a las principales áreas que necesitan lubricación.

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Glossary Oil pan gaskets Oil pan gaskets are used to prevent leakage from the crankcase at the connection between the oil pan and the engine block. Juntas del colector de aceite Las juntas del colector de aceite se utilizan para impedir las fugas del cárter en la conexión entre el colector de aceite y el bloque del motor. Oil pump The oil pump creates a vacuum so atmospheric pressures can push oil from the sump. The pump then pressurizes the oil and delivers it throughout the engine by use of galleries. Bomba de aceite La bomba de aceite crea un vacío para que la presión atmosférica pueda empujar el aceite desde el depósito de aceite. Luego la bomba presuriza el aceite y lo envía al motor a través de canales. Oil sludge Oil sludge buildup occurs when the oil gels and thickens due to oxidizing. Sedimento de aceite La acumulación de sedimentos de aceite se produce cuando el aceite se gelifica y se espesa debido a la oxidación. Open loop system An open loop system delivers fuel based on demand and has no way of detecting whether the amount sent was ideal in terms of performance, emissions, or fuel economy. Mecanismo de bucle abierto El mecanismo de bucle abierto entrega combustible basado en la demanda y no tiene manera de detectar si la cantidad que mandó era la ideal en términos de rendimiento, emisiones o economía del combustible. Overhead camshaft engine (OHC) If a cylinder head contains the camshaft, it is called an overhead camshaft engine. The camshaft can also be located in the cylinder block. Motor de árbol de levas en la culata Si la culata del cilindro contiene el árbol de levas, se denomina motor de árbol de levas en la culata (OHC, por la sigla en inglés de “OverHead Cam”). El árbol de levas también puede estar en el bloque de cilindros. Overhead valve (OHV) An overhead valve engine has the valves mounted in the cylinder head and the camshaft mounted in the block. Válvula en culata Un motor de válvulas en culata (OHV, por sus siglas en inglés) tiene las válvulas montadas en la culata del cilindro y el árbol de levas montado en el bloque. Oversize bearings Oversize bearings are thicker than standard, with the outside diameter increased in order to fit an oversize bearing bore. The inside diameter is the same as standard bearings. Cojinetes de medidas superiores Los cojinetes de medidas superiores son más gruesos que los cojinetes estándar para aumentar el diámetro externo a fin de adaptarlo a un calibre de mayor tamaño. El diámetro interno es igual al de los cojinetes estándar. Oxidation Oxidation occurs when hot engine oil combines with oxygen and forms carbon. Oxidación La oxidación ocurre cuando el aceite caliente del motor se combina con oxígeno y forma carbono. Oxidation inhibitors The formation of gum and varnish is prevented by oxidation inhibitors. Antioxidantes Los antioxidantes evitan la formación de resinas y barniz. Parallel system A parallel system HEV can use the electric motor and the engine to power the vehicle. It can also use just one power source at a time. Sistema paralelo Los vehículos híbridos eléctricos con sistema paralelo se impulsan mediante un motor eléctrico y un motor de combustión interna. Pueden utilizar una sola fuente de alimentación a la vez.

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Pedestal-mounted rocker arm A pedestal-mounted rocker arm is mounted on a threaded pedestal that is an integral part of the cylinder head. Palanca de basculador montada en pedestal La palanca de basculador montada en pedestal está montada en un pedestal enroscado que es una parte integral de la cabeza del cilindro. Pentroof combustion chambers Pentroof combustion chambers are a common design for multivalve engines using two intake valves with one or two exhaust valves and provide good S/V ratio. Cámaras de combustión con parte superior inclinada Las cámaras de combustión con parte superior inclinada son un diseño frecuente en los motores multiválvulas que utilizan dos válvulas de admisión y una o dos válvulas de escape, y que ofrecen una buena relación superficie-volumen (S/V). Piezoresistive sensor A piezoresistive sensor is sensitive to pressure changes. The most common use of this type of sensor is to measure the engine oil pressure. Sensor piezorresistente El sensor piezorresistente es sensible a los cambios de presión. El uso más común para este tipo de sensor es el de medir la presión del aceite del motor. Piston The piston is a round-shaped part that is driven up and down in the engine cylinder bore. Pistón El pistón es una pieza redondeada que es impulsada hacia arriba y hacia abajo en el calibre del cilindro del motor. Piston rings Piston rings are hard cut rings that fit around the piston to form a seal between the piston and the cylinder wall. Anillos de pistón Los anillos o aros de pistón son anillos con perfiles definidos que se ubican alrededor del pistón para formar un sello entre el pistón y la pared del cilindro. Pitch Pitch is the number of threads per inch on a bolt in the USC system. Declive El declive es el número de roscas por pulgada en un tornillo en el sistema de medidas acostumbradas en EU. Plastics Plastics are made from petroleum and are used in several engine components because of their light weight and heat transfer properties. Plástico El material plástico se fabrica con petróleo y se utiliza en varios componentes del motor por sus propiedades de transferencia térmica y su peso liviano. Pole shoes Pole shoes are made of high magnetic permeability material to help concentrate and direct the lines of force in the field assembly. Expansiones polares Las expansiones polares están hechas con un material de alta impermeabilidad magnética que ayudan a concentrar y dirigir las isostáticas en el ensamblado de campo. Poppet valves Poppet valves control the opening or passage by linear movement. Válvulas de resorte Las válvulas de resorte controlan la abertura o pasaje mediante un movimiento lineal. Positive displacement pumps Positive displacement pumps deliver the same amount of oil with every revolution, regardless of speed. Bombas de desplazamiento positivo Las bombas de desplazamiento positivo suministran la misma cantidad de aceite en cada revolución, independientemente de la velocidad. Potential energy The energy that is not being used at a given time, but which can be used. Energía potencial La energía potencial es la energía que no está usándose en un tiempo específi co, pero que puede usarse.

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Glossary

Power splitting device A power splitting device changes the mode of power delivery from one source to the other or to a combination of both sources. Dispositivo de división de la potencia Un dispositivo de division de la potencia cambia el modo de entregar la potencia de una fuente a otra o a una combinación de ambas fuentes. Powertrain A powertrain includes the engine and all the components that deliver that force to the road, including the transmission and axles. Motor El motor incluye a la máquina y todos los componentes que entregan esa fuerza en el camino, incluyendo la transmisión y los ejes. Powertrain control module (PCM) An onboard computer that controls functions related to the powertrain, such as fuel delivery, spark timing, temperature, and shift points. Módulo de control del tren de potencia El módulo de control del tren de potencia (PCM, por sus siglas en inglés) es una computadora de a bordo que controla funciones relacionadas con el tren de potencia, como el suministro de combustible, la sincronización del encendido, la temperatura y los puntos de cambio. Preignition Preignition is an explosion in the combustion chamber resulting from the air-fuel mixture igniting prior to the spark being delivered from the ignition system. Preencendido El preencendido es una detonación en la cámara de combustión que se produce cuando la mezcla de aire y combustible se enciende antes de que el sistema de encendido suministre la llama. Prove-out circuit A prove-out circuit completes the warning light circuit to ground through the ignition switch when it is in the start position. The warning light will be on during engine cranking to indicate to the driver that the bulb is working properly. Circuito de comprobación Un circuito de comprobación complete el circuito de luz de alerta a tierra mediante el interruptor de encendido cuando está en la posición de iniciar. La luz de alerta se encenderá durante el arranque del motor para indicarle al conductor que el foco está funcionando apropiadamente. Pumping losses Pumping losses are wasted power from the pistons pushing up against compressed air during the compression stroke. Saldo de bombeo Los saldos de bombeo son potencia perdida de los pistones empujando hacia el aire comprimido durante los golpes de compresión. Pump-up Lifter pump-up occurs when excessive clearance in the valvetrain allows a valve to float. The lifter attempts to compensate for the clearance by filling with oil. The valve is unable to close, since the lifter does not leak down fast enough. Bombear Los bombeos del empujador suceden cuando la holgura excesiva en el tren de la válvula permite que fl ote la válvula. El levantador intenta compensar por la holgura al llenarla de aceite. La válvula no puede cerrarse ya que el levantador no deja que gotee lo sufi cientemente rápido. Pushrod A long tube that connects the camshaft to the valvetrain components in the cylinder head. This is typically not used on an OHC engine. Varilla de empuje La varilla de empuje es un tubo largo que conecta el árbol de levas con los componentes del tren de válvulas situado en la cabeza del cilindro. Habitualmente no se utiliza en los motores OHC.

Quenching Quenching is the cooling of gases as a result of compressing them into a thin area. The quench area has a few thousandths of an inch clearance between the piston and combustion chamber. Placing the crown of the piston this close to the cooler cylinder head prevents the gases in this area from igniting prematurely. Amortiguamiento El amortiguamiento es el enfriamiento rápido de los gases que se produce al comprimirlos en un área estrecha. El área de amortiguación es un espacio libre de unas milésimas de pulgada entre el pistón y la cámara de combustión. Al colocar la corona del pistón muy cerca de la culata del cilindro del enfriador, se evita que los gases de esta área se enciendan de manera prematura. Radiator The radiator is a heat exchanger used to transfer heat from the engine to the air passing through it. Radiador El radiador es un intercambiador de calor que se utiliza para transferir calor del motor al aire que lo atraviesa. Rear main seal The rear main seal is a seal installed behind the rear main bearing on the rear main-bearing journal to prevent oil leaks. Junta principal posterior La junta principal posterior es un sello insta-lado detrás del cojinete principal posterior en el gorrón del cojinete principal posterior para prevenir fugas de aceite. Reciprocating A repetitive up-and-down or back-and-forth motion. Recíproco Se llama recíproco a un movimiento repetitivo de arriba a abajo o de un lado a otro. Reed valve A reed valve is a one-way check valve. The reed opens to allow the air-fuel mixture to enter from one direction, while closing to prevent movement in the other direction. Válvula de lengüeta La válvula de lengüeta es una válvula de una vía. La lengüeta se abre para permitir que la mezcla de aire y combustible ingrese desde una dirección y se cierra para impedir el movimiento en la dirección contraria. Regenerative braking Regenerative braking uses the lost kinetic energy during braking to help recharge the batteries. Frenado regenerativo El frenado regenerativo utiliza la energía cinética perdida durante el frenado para ayudar a recargar las baterías. Reid vapor pressure (RVP) A method of describing the volatility of the fuel. You can test the RVP to rate the fuel’s volatility. Presión de vapor Reid La presión de vapor Reid (RVP, por sus siglas en inglés) es un método que permite describir la volatilidad del combustible. Se pueden hacer pruebas de RVP para calcular la volatilidad del combustible. Remanufactured engine An engine that has been professionally rebuilt by a manufacturer or engine supplier. Motor re-fabricado Un motor re-fabricado es el que el fabricante o un proveedor de motores volvió a fabricar profesionalmente. Research Octant Number (RON) RON and MON are octane testing numbers that are averaged together to get the advertised octane number. Each uses a different test procedure that represents different real-world driving situations. Número de octanos del motor El número de octanos de carretera y el número de octanos del motor (RON y MON respectivamente, por sus siglas en inglés) representan números obtenidos en pruebas de octanaje que se promedian para obtener el número de octanos publicado. Cada uno utiliza un procedimiento de prueba diferente que representa diferentes condiciones de conducción reales.

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Glossary Resonator A device mounted on the tailpipe to reduce exhaust noise. Resonador El resonador es un dispositivo montado en el tubo de escape para reducir más el ruido de escape. Retarded camshaft A retarded camshaft has the exhaust valve open more than the intake at TDC. Árbol de levas atrasado Un árbol de levas atrasado tiene la válvula de escape más abierta que la válvula de admisión cuando se encuentra en el punto muerto superior. Retrofitted A vehicle that was originally designed to run on gasoline but has been changed to run on an alternate fuel is often called retrofitted or converted. Modificado Los vehículos diseñados originalmente para funcionar con gasolina que se modifican para funcionar con combustibles alternativos suelen llamarse modificados o convertidos. Reverse flow cooling system In a reverse flow cooling system, coolant flows from the water pump through the cylinder heads and then through the engine block. Sistema de enfriamiento de flujo inverso En un sistema de enfriamiento de flujo inverso, el refrigerante fluye desde la bomba de agua y atraviesa las culatas de los cilindros y luego el bloque del motor. Ring gear The ring gear around the circumference of a flywheel or flexplate allows the starter motor drive ear to turn the engine. Some flexplates and flywheels are used as part of a sensor to determine the speed of the engine. Engranaje anular El engranaje anular que rodea la circunferencia del volante o el plato flexible permite que el engranaje de mando del motor de arranque ponga en marcha el motor. Algunos volantes y platos flexibles forman parte de un sensor que determina la velocidad del motor. Rocker arm A pivoting lever used to transfer the motion of the pushrod to the valve stem. Balancín El balancín es una palanca pivotante que se utiliza para transferir el movimiento de la varilla de empuje al vástago de la válvula. Rocker arm ratio The difference in the rocker arm dimensions from center to valve stem and center to pushrod is called the rocker arm ratio. It is a mathematical expression of the leverage being applied to the valve stem. Relación del balancín Se denomina relación del balancín a la diferencia en las dimensiones del balancín desde el centro hasta el vástago de la válvula y desde el centro hasta la varilla de empuje. Es una expresión matemática de la fuerza de palanca que se aplica al vástago de la válvula. Roller lifter A normal lifter with a rolling pin on the bottom to decrease friction. Alzaválvulas de rodillo Un alzaválvulas de rodillo es un alzaválvulas normal que tiene un rodillo en la parte superior para disminuir la fricción. Room-temperature vulcanizing (RTV) Room-temperature vulcanizing (RTV) is a type of liquid gasket maker that may be used in place of a gasket on some applications. Vulcanización a temperatura ambiente La vulcanización a temperatura ambiente (RTV, por sus siglas en inglés) hace referencia a un tipo de sellador de motor que puede utilizarse en lugar de las juntas en algunas aplicaciones. Roots-type supercharger The Roots-type supercharger is a positive displacement supercharger that uses a pair of lobed vanes to pump and compress the air. Sobrealimentador tipo Roots El sobrealimentador tipo Roots es un sobrealimentador de desplazamiento positivo que utiliza un par de aletas con lóbulos para bombear y comprimir el aire.

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Rotary valve A valve that rotates to cover and uncover the intake port. Válvula rotativa Una válvula rotativa es aquella que gira para tapar y destapar el puerto de admisión. Saddle The portion of the crankcase bore that holds the bearing half in place. Asiento El asiento es la parte del calibre del cigüeñal que mantiene la mitad del cojinete en su lugar. S-class oil S-class oil is used for automotive gasoline engines. Aceite clase S El aceite clase S está diseñado para motores de automóviles a gasolina. Sealants Sealants are commonly used to fill irregularities between the gasket and its mating surface. Obturadores Los obturadores generalmente se utilizan para rellenar las irregularidades entre una junta y la superficie de contacto. Algunos obturadores están diseñados para reemplazar a las juntas. Seals Seals are used to prevent leakage of fluids around a rotating part. Sellos Los sellos se utilizan para evitar fugas de fluidos alrededor de las piezas giratorias. Series system A series system HEV uses the electric motor to drive the vehicle; the gas motor recharges the batteries to power the electric motor. Sistema en serie Los vehículos híbridos eléctricos con sistema en serie se impulsan con el motor eléctrico. El motor a gas recarga las baterías para alimentar el motor eléctrico. Service sleeves Service sleeves (sometimes referred to as speedy-sleeves) press over the damaged sealing area to provide a new, smooth surface for the seal lip. Manguitos de desgaste Los manguitos de desgaste (a veces llamados manguitos de servicio o speedi-sleeve) ejercen presión sobre el área de sellado dañada y proporcionan una nueva superficie lisa para el reborde del sello. Shaft-mounted rocker arms Shaft-mounted rocker arms are used in a mounting system that positions all rocker arms on a common shaft mounted above the cylinder head. Conjunto de levanta válvulas montadas en el eje El conjunto de le-vanta válvulas montadas en el eje se usan en un sistema de montaje que coloca todo el conjunto de levanta válvulas en un eje común montado encima de la cabeza del cilindro. Short block A block assembly without the cylinder heads and some other components. Bloque corto Un bloque corto es el ensamblado de bloque sin las cabezas del cilindro y algunos otros componentes. Shot peening A cold-working process used to make the outer layers of a metal more compressive. Granallado de compresión El granallado de compresión, o shotpeening, es un proceso de forjado en frío que se utiliza para aumentar la compresión de las capas externas de un metal. Sintering Powder metallurgy is the manufacture of metal parts by compacting and sintering metal powders. Sintering is done by heating the metal to a temperature below its melting point in a controlled atmosphere. The metal is then pressed to increase its density. Sinterización La pulvimetalurgia fabrica piezas metálicas mediante la compactación y la sinterización de polvos metálicos. La sinterización se realiza calentando el metal a una temperatura inferior al punto de fusión en una atmósfera controlada. Posteriormente, el metal se prensa para aumentar su densidad.

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Glossary

Skin effect Skin effect is a small layer of unburned gases formed around the walls of the combustion chamber. Efecto superficial El efecto superficial o pelicular consiste en la formación de una pequeña capa de gases no quemados alrededor de las paredes de la cámara de combustión. Solenoid Is an electromechanical device changing electricity into mechanical motion such as a fuel injector. Solenoide Es un dispositivo electromecánico que cambia la electricidad en movimiento mecánico, como un inyector de combustible. Spark-ignition (SI) engine A spark-ignition (SI) engine ignites the air-fuel mixture in the combustion chamber by a spark across the spark plug electrodes (this engine is often fueled by gasoline, propane, ethanol, or natural gas). Motor de encendido por chispa Los motores de encendido por chispa (SI, por sus siglas en inglés) encienden la mezcla de aire y combustible en la cámara de combustión mediante una chispa entre los electrodos de la bujía (estos motores suelen funcionar con gasolina, propano, etanol o gas natural). Splayed crankshaft A splayed crankshaft is a crankshaft in which the connecting rod journals of two adjacent cylinders are off set on the same throw. Cigüeñal ensanchado Un cigüeñal ensanchado es un cigüeñal en el que los gorrones de la biela de dos cilindros adyacentes no están paralelos en el mismo alcance. Squish area The squish area of the combustion chamber is the area where the piston is very close to the cylinder head. The air-fuel mixture is rapidly pushed out of this area as the piston approaches TDC, causing a turbulence and forcing the mixture toward the spark plug. The squish area can also double as the quench area. Área de compresión El área de compresión, o squish, de la cámara de combustión es el área donde el pistón se encuentra muy cerca de la culata del cilindro. La mezcla de aire y combustible es expulsada rápidamente de esta área cuando el pistón se aproxima al punto muerto superior, lo que genera una turbulencia y empuja la mezcla hacia la bujía. El área de compresión también puede funcionar como área de amortiguación. Stainless steel Stainless steel is an alloy that is highly resistant to rust and corrosion. Acero inoxidable El acero inoxidable es una aleación que es altamente resistente a la oxidación y la corrosión. Steel Iron containing very low carbon (between 0.05 and 1.7 percent) is called steel. Acero El hierro que contiene muy bajo carbono (entre 0.05 y 1.7 por ciento) se llama acero. Stellite A hard facing material made from a cobalt-based material with a high chromium content. Estelita La estelita es un material de revestimiento duro fabricado con un material con base de cobalto y un alto contenido de cromo. Stem necking Stem necking is a condition of the valve stem in which the stem narrows near the bottom. Rebajamiento del vástago El rebajamiento del vástago es una condición del vástago de la válvula en el que el vástago se estrecha cerca del fondo. Stratified-charge A stratified-charge engine has two combustion chambers. A rich air-fuel mixture is supplied to a small auxiliary chamber, and the very lean air-fuel mixture is supplied to the main combustion chamber. Carga estratificada Un motor de carga estratificada tiene dos cámaras de combustión. Se suministra una mezcla rica de aire y combustible a una cámara auxiliar pequeña y una mezcla de aire y combustible muy pobre a la cámara de combustión principal.

Strip seal A strip seal provides a seal between the flat surfaces on the front and back of the engine block and the intake manifold. Junta de impermeabilización Una junta de impermeabilización proporciona un sello entre las superfi cies planas del frente y la parte posterior del bloque motor y del colector de entrada. Stroke The distance that the piston travels from TDC to BDC or vice versa. The stroke is the amount of piston travel from TDC to BDC measured in inches or millimeters. Carrera La carrera es la distancia que recorre el pistón desde el punto muerto superior hasta el punto muerto inferior o viceversa. La carrera es la longitud de recorrido del pistón desde el punto muerto superior hasta el punto muerto inferior, expresada en pulgadas o milímetros. Stud-mounted rocker arm A stud-mounted rocker arm is mounted on a stud that is pressed or threaded into the cylinder head. Balancín montado en perno El balancín montado en perno se monta sobre un perno que está roscado o presionado contra la culata del cilindro. SULEV A SULEV vehicle produces an extremely low measurable amount of pollution from its tailpipe. This is a Federal government vehicle standard. Vehículo de emisiones superultrabajas Un vehículo de emisiones superultrabajas, o SULEV, por sus siglas en inglés, emite una cantidad extremadamente baja de contaminación por el tubo de escape. Es una norma para vehículos del Gobierno Federal de EE. UU. Supercharger The supercharger is a belt-driven air pump used to increase the compression pressures in the cylinders. Sobrealimentador El sobrealimentador es una bomba de aire impulsada por correas que se utiliza para aumentar las presiones de compresión en los cilindros. Surface-to-volume (S/V) ratio A high surface-to-volume ratio results in higher HC emissions. The S/V ratio is a mathematical comparison between the surface area of the combustion chamber and the volume of the combustion chamber. A typical S/V ratio is 7.5:1. Relación superficie-volumen Una relación superficie-volumen (S/ V) alta genera emisiones más elevadas de hidrocarburos. La relación S/V es una comparación matemática entre la superficie y el volumen de la cámara de combustión. Una relación S/V típica es 7.5:1. Swirl chambers Swirl chambers create an airflow that is in a horizontal direction. Cámaras de turbulencia Las cámaras de turbulencia crean un flujo de aire con dirección horizontal. Tailpipe The tailpipe conducts exhaust gases from the muffler to the rear of the vehicle. Tubo de escape El tubo de escape conduce los gases de emission desde el mofl e a la parte posterior del vehículo. Tapered piston A tapered piston is narrower at the top of the piston where it will expand when heated to become a similar diameter. Pistón cónico Un pistón cónico es más angosto en la parte superior; al calentarse, esta parte se expande para alcanzar un diámetro similar al de la parte inferior. Tempering In tempering, metal is heated to a specific temperature to reduce the brittleness of hardened carbon steel. Templado En el proceso de templado, el metal se calienta a una temperatura específica para reducir la fragilidad del acero al carbono endurecido.

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Glossary Tensile strength Tensile strength is the metal’s resistance to being pulled apart. Resistencia a la tracción La resistencia a la tracción es la resistencia del metal a ser separado. Tetraethyl (TEL) TEL is not used as an additive in gasoline anymore. Unleaded gasoline is readily available and is less toxic. Tetraetilo (TEL) El tetraetilo ya no se utiliza como aditivo en la gasolina. Actualmente, se dispone de gasolina sin plomo, que es menos tóxica. Thermal efficiency The difference between potential and actual energy developed in a fuel measured in Btus per pound or gallon. Rendimiento térmico El rendimiento térmico es la diferencia entre la energía potencial y la energía real que se desarrolla en un combustible, expresada en BTU por libra o por galón. Thermistor A resistor whose resistance changes in relation to changes in temperature. It is often used as a coolant temperature sensor. Termistor El termistor es un resistor cuya resistencia cambia en relación con los cambios de temperatura. A menudo se utiliza como sensor de temperatura del refrigerante. Thermodynamics The study of the relationship and efficiency between heat energy and mechanical energy. Termodinámica La termodinámica es el estudio de la relación y el rendimiento de la energía térmica y la energía mecánica. Thermostat A mechanical component that blocks or allows coolant flow to the radiator. The thermostat allows the engine to quickly reach normal operating temperatures and maintains the desired temperature. Termostato El termostato es un componente mecánico que bloquea o permite el flujo de refrigerante hacia el radiador. El termostato permite que el motor alcance rápidamente una temperatura de funcionamiento normal y mantenga la temperatura deseada. Thread depth The height of the thread from its base to the top of its peak. Profundidad de la rosca La profundidad de la rosca es la altura de la rosca medida desde la base hasta la parte superior. Thrust bearing The thrust bearing prevents the crankshaft from sliding back and forth by using flanges that rub on the side of the crankshaft journal. Cojinete de empuje El cojinete de empuje evita que el cigüeñal se deslice de un lado a otro utilizando bridas que rozan la parte lateral del muñón del cigüeñal. Timing chain guide A timing chain guide is a length of metal with a soft face to hold the chain in position as it rotates. Guía de la cadena de distribución La guía de la cadena de distribución es una extensión de metal con una cara lisa que mantiene la cadena en su lugar mientras gira. Timing chain tensioner A timing chain tensioner maintains tension on the chain or belt to prevent slapping or skipping a tooth. Tensor de la cadena de tiempo El tensor de la cadena de tiempo mantiene la tensión en la cadena o banda para prevenir el ruido de impulso o saltearse un diente. Top dead center (TDC) A term used to indicate that the piston is at the very top of its stroke. Punto muerto superior El punto muerto superior (TDC, por sus siglas en inglés) es un término utilizado para indicar que el pistón se encuentra en la posición más elevada de su carrera. Torque A rotating force around a pivot point.

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Torsión La torsión es una fuerza giratoria alrededor de un punto de pivote. Torque converter The torque converter mounts to the crankshaft through a flexplate. Its weight and fluid coupling do a fine job of maintaining a more constant crankshaft speed. Convertidor de torsión El convertidor de torsión se monta en el cigüeñal mediante un plato flexible. Por su peso y su acoplamiento fluido es eficaz para mantener más constante la velocidad del cigüeñal. Torque-to-yield Torque-to-yield is a stretch-type bolt that must be tightened to a specific torque and then rotated a certain number of degrees. De tensión a rendimiento De tensión a rendimiento es un tornillo de tipo alargado que debe estar apretado a una tensión específi ca y luego girarlo a cierto número de grados. Torsional vibration Torsional vibration is the result of the crankshaft twisting and snapping back during each revolution. Vibración torsional La vibración torsional se produce debido a que el cigüeñal gira y vuelve rápidamente a su lugar en cada revolución. Transmission The transmission is a device that uses the rotary motion and power of the crankshaft to turn the differential and drive shafts. The transmission multiplies the power output and changes the speed of the driveshaft using different gear ratios. Transmisión La transmisión es un dispositivo que emplea el movimiento giratorio y la potencia del cigüeñal para hacer girar el diferencial y los ejes motores. La transmisión multiplica la potencia de salida y cambia la velocidad del eje motor utilizando diferentes relaciones de transmisión. Transverse-mounted engine When an engine is mounted perpendicular to the drivetrain, it is said to be a transversemounted engine. Motor transversal Cuando un motor está montado en posición perpendicular al tren de transmisión, se lo denomina motor transversal. Tumble port Tumble port combustion chambers use a modified intake port design. Puerto invertido Las cámaras de combustión con puerto invertido tienen un puerto de admisión con diseño modificado. Turbine wheel A turbine wheel is a vaned wheel in a turbocharger to which exhaust pressure is supplied to provide shaft rotation. Rodete Un rodete es una rueda de paletas en un turboalimentador en la cual la presión de salida se suministra para proporcionar la rotación del eje. Turbo boost A term used to describe the amount of positive pressure increase of the turbocharger; for example, 10 psi (69 kPa) of boost means the air is being induced into the engine at 24.7 psi (170 kPa). Normal atmospheric pressure is 14.7 psi (101 kPa); add the 10 psi (69 kPa) to get 24.7 psi (170 kPa). Turbosoplante Turbosoplante es un término que se usa para describir la cantidad de aumento de presión positiva del turboalimentador; por ejemplo, 10 psi (69 kPa) de soplo signifi ca el aire que se introduce en el motor a 24.7 psi (170 kPa). La presión atmosférica normal es de 14.7 psi (101 kPa); se añaden los 10 psi (69 kPa) para obtener 24.7 psi (170 kPa). Turbocharger A turbocharger uses the expansion of exhaust gases to rotate a fan-type wheel, which increases the pressure inside the intake manifold. Turbo sobrealimentador El turbo sobrealimentador utiliza la expansión de los gases de escape para hacer girar una rueda similar a un ventilador y aumentar la presión dentro del múltiple de admisión.

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Glossary

Turbo lag Turbo lag is a short delay period before the turbocharger develops sufficient boost pressures. Demora de respuesta La demora de respuesta es el breve período antes de que el turbo sobrealimentador desarrolle presiones de sobrealimentación suficientes. Turbulence The movement of air inside the combustion chamber. Turbulencia La turbulencia es el movimiento de aire dentro de la cámara de combustión. Undersize bearings Undersize bearings have the same outside diameter as standard bearings, but the bearing material is thicker to fit an undersize crankshaft journal. Cojinetes de medidas inferiores Los cojinetes de medidas inferiores tienen el mismo diámetro externo que los cojinetes estándar, pero el material de apoyo tiene mayor espesor para adaptarse a un muñón de cigüeñal más pequeño. Vacuum A space in which the pressure is significantly lower than the pressure around it. In an engine, we define this as the pressure inside the engine being less than atmospheric and therefore a vacuum exists. Vacuum is considered a force and can move fluids from their rest position. Vacío El vacío es un espacio cuya presión es significativamente inferior a la presión circundante. En un motor, el vacío se produce cuando la presión dentro del motor es inferior a la presión atmosférica. Se considera que el vacío es una fuerza capaz de poner en movimiento fluidos que se encuentran en reposo. Valley pans Valley pans prevent the formation of deposits on the underside of the intake manifold. Bandejas cóncavas Las bandejas cóncavas impiden la formación de depósitos en el lado inferior del múltiple de admisión. Valve cover gaskets Valve cover gaskets seal the connection between the valve cover and the cylinder head. The gasket is not subject to pressures, but must be able to seal hot, thinning oil. Juntas de la tapa de la válvula Las juntas de la tapa de la válvula sellan la conexión entre la tapa de la válvula y la culata del cilindro. La junta no está sometida a presión, pero debe ser capaz de impedir el paso de aceite caliente muy ligero. Valve float Valve float is a condition that allows the valve to remain open longer than intended. It is the effect of inertia on the valve. Flotación de la válvula La flotación de la válvula es una situación en que la válvula puede permanecer abierta por un período mayor al previsto. Es el efecto de la inercia en la válvula. Valve guides Valve guides support and guide the valve stem through the cylinder head. Guías de la válvula Las guías dan apoyo y guían al vástago de la válvula a través de la culata del cilindro. Valve job A valve job includes refinishing or replacing the valves and seats and any other worn components in the valvetrain. Trabajo en válvulas El trabajo en válvulas consiste en restaurar o reemplazar las válvulas y los asientos, así como cualquier otro componente desgastado del tren de válvulas. Valve lift Valve lift is the total movement of the valve off of its seat, expressed in inches or millimeters. Carrera de la válvula La carrera de la válvula es el movimiento total de la válvula fuera de su asiento, y se expresa en milímetros o en pulgadas. Valve overlap When the intake and exhaust valves are both open at the same time an engine has valve overlap.

Superposición de válvulas Cuando las válvulas de admisión y de escape están abiertas al mismo tiempo, el motor tiene superposición de válvulas. Valve seats Provides the mating surface for the valve face. Asientos de las válvulas Proporcionan la superficie de contacto de la cara de la válvula. Valve seat inserts Valve seat inserts are pressed into a machined recess in the cylinder head. Insertos del asiento de la válvula Los insertos del asiento de la válvula están prensadas dentro de la ranura torneada de la cabeza del cilindro. Valve seat recession Valve seat recession is the loss of metal from the valve seat, causing the seat to recede into the cylinder head. Retroceso del asiento de la válvula El retroceso del asiento de la válvula se produce cuando el asiento de la válvula pierde metal y queda retraído en la culata del cilindro. Valve spring A valve spring connects to the valve by a keeper and retainer, and pulls the valve back into the valve seat, thus putting the valve in a closed position where no fuel or air can pass through it. Muelle de la válvula El muelle de la válvula está conectado a la válvula mediante una abrazadera y retén, y comprime la válvula contra el asiento de manera que quede en una posición de cierre que no permita el paso de aire o combustible. Valve stem The valve stem guides the valve through its linear movement. Vástago de la válvula El vástago de la válvula guía la válvula a través de su movimiento linear. Valve timing Refers to the relationship between the rotation of the crankshaft and camshaft. That correct relationship ensures that the valves open at the correct time. Reglaje de válvula El reglaje de válvula se refi ere a la relación entre el giro del cigüeñal y del árbol de levas. Esa correcta relación asegura que las válvulas se abren al tiempo correcto. Valve timing mechanism The valve timing mechanism drives the camshaft in the correct timing with the crankshaft. It may use a belt, chain, or gears. Mecanismo de reglaje de válvula El mecanismo de reglaje de válvula corre el árbol de levas en la puesta a punto correcta con el cigüeñal. Puede hacer uso de una banda, una cadena o ruedas dentadas. Valvetrain The valvetrain is made up of the components that open and close the valves. Tren de válvulas El tren de válvulas está formado por los componentes que abren y cierran las válvulas. Variable cylinder displacement Allows the cancelation of individual cylinders for better fuel economy. Cilindrada variable permite cancelar cilindros individuales para mejorar el ahorro de combustible. Variable-length intake manifold The variable-length intake manifold has two runners of different lengths connected to each cylinder head intake port. Colector de entrada de longitud variable El colector de entrada de longitud variable tiene dos muelas de diferentes longitudes conectadas a cada orifi cio de admisión de la cabeza del cilindro. Variable valve timing (VVT) systems Refers to an engine that uses an adjustable valve train to vary the amount and timing of an air/fuel mixture entering or leaving a cylinder.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Glossary Sistemas de ajuste de válvula variable (VVT) Usan un tren de válvulas variable para variar el tiempo y la cantidad de aire/ combustible que entra al motor. Viscosity The measure of the resistance of the oil when placed under shear and extensional stress (the same stresses placed on oil by the crankshaft and connecting rod bearings). It is used to describe an oil’s internal resistance to flow. Technicians often use viscosity to describe an oil’s thickness or weight. Viscosidad La viscosidad es la medida de la resistencia del aceite al someterlo a esfuerzo cortante y elongacional (el mismo esfuerzo al que lo someten los muñones de los cojinetes de la biela y el cigüeñal). Se utiliza para describir la resistencia interna al flujo del aceite. Los técnicos a menudo utilizan la viscosidad para describir la densidad o el peso de un aceite. Viscosity index A measure of the change in viscosity an oil will have with changes in temperature. Índice de viscosidad El índice de viscosidad de un aceite es la medida del cambio en la viscosidad que experimentará el aceite con las variaciones de temperatura. Volatility Fuel volatility is the ability of the fuel to vaporize. The higher the volatility, the easier it is for the fuel to evaporate; this allows easier cold starts. Volatilidad La volatilidad del combustible es su capacidad de evaporación. Cuanto mayor es la volatilidad, más fácil es que se evapore el combustible. Esto facilita el arranque en frío. Volumetric efficiency The comparison between the amount of air that could enter the engine and the amount of air that actually enters the engine. Rendimiento volumétrico El rendimiento volumétrico es la relación entre la cantidad de aire que podría ingresar al motor y la cantidad de aire que ingresa realmente.

313

Warning light A lamp that is illuminated to warn the driver of a possible problem or hazardous condition. Luz de alerta La luz de alerta es una lámpara que está prendida para avisarle al conductor de un posible problema o de una condición peligrosa. Wastegate A wastegate limits the maximum amount of turbocharger boost by directing the exhaust gases away from the turbine wheel. The wastegate valve is also referred to as a bypass valve. Válvula de expulsión La válvula de expulsión limita la maxima cantidad de empuje del turboalimentador al desviar los gases de escape de la rueda de la turbina. La válvula de expulsión también se conoce como válvula de desviación. Wedge chamber Wedge chamber design locates the spark plug between the valves in the widest portion of the wedge in the cylinder head. Cámara en cuña En el diseño de cámara en cuña, la bujía se encuentra entre las válvulas en la parte más ancha de la cuña, en la culata del cilindro. Wrist pin A wrist pin is a hardened steel pin that connects the piston to the connecting rod and allows the rod to rock back and forth as it travels with the crankshaft. Pasador del pistón El pasador del pistón es un pasador de acero endurecido que conecta el pistón con la biela y permite que la biela se balancee de un lado a otro mientras se desplaza con el cigüeñal. Zero lash The point at which there is no clearance or interference between components of the valvetrains. Holgura cero La holgura cero es el punto en el que no hay holgura ni interferencia entre los componentes de los trenes de válvulas.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

INDEX

Page numbers followed by “f ” indicate figure.

A Abnormal combustion, 113 support systems’ contribution, 115 Active fuel management system, 228–230 Additives, gasoline, 100–101 detergents, 101 oxidation inhibitors, 101 tetraethyl (TEL) lead, 100 Adhesives, 138–139 Advanced camshaft, 204 Advanced Technology Partial Zero– Emissions Vehicle (AT-PZEV) standard, 283 Aerobic sealants, 138 Air, 30 flow of, through supercharger system components, 157, 157f Air cleaner/filter, 143–146 design, 144–146 function of, 143 Airflow restriction indicator, 144 Air induction system, 142 Air intake ductwork, 143 Air pollution, 98, 272 Air-to-fuel ratio, 94 Alloys, 119 Alternative fuel vehicles, 273 Aluminized valves, 183 Aluminum, 120–121, 123 Aluminum alloy, 121, 178, 234 American Petroleum Institute (API), 67 Starburst symbol, 68, 69f Anaerobic sealants, 138 Annealing, 125 Antifoaming agents, 66 Antifreeze, 77, 80 Antioxidation agents, 66 Armature, 64 Atkinson-cycle engine, 227, 290–291 Atmospheric pressure, 30–31 Autoignite, 115 Autoignition temperature, 32

314

Automotive Engine Rebuilders Association (AERA), 205 Automotive engines. See Engines Automotive fuels, 98–102 ethanol, 100 gasoline, 98 additives, 100–101 octane number, 98–99

B Babbitt, Isaac, 257 Back pressure, 164 Balance shafts, 39, 39f, 40f, 257 bearings, 257 Batteries, 62–64, 288–289, 289f Battery Council International (BCI), 63 Battery terminals, 62 Bearing crush, 253, 253f Bearing inserts, 180f, 240, 250, 253. See also Bearings Bearing journals, 39 Bearings, 250–257. See also Bearing inserts balance shaft, 257 camshaft, 205, 205f, 257, 257f characteristics, 253–254 connecting rod, 253–255 construction of, 252 main, 254 materials, 252–253 oil clearances, 255–256 rod, 255 thrust, 255 undersize and oversize, 256 Bearing spread, 253 Bedplate, 236 Belt-driven systems, 221–223 Bentley Motors, 245 Biodiesel fuels, 102 Biomass-to-liquid (BTL), 101 Block construction. See Cylinder block Blow-by, 266 Blower, 150, 155

Body control module (BCM), 91 Bolt diameter, 127 length, 127 metric, 127, 130f standard, 129f torque-to-yield, 128–130 typical, 127f Bolt-grade, 127, 128f Boost pressure control, 152 Bores, 40, 41f camshaft, 179–180 cylinder, 239 lifter, 245 main, 240 Bottom dead center (BDC), 32 Boxer engine, 35 Boyle’s law, 31 Brackets, 164–165 Brake horsepower, 45 Breakage, of valve, 184 Breakdown, oil, 70 Buick, changes since 1954, 213 Burned valves, 183–184 Burn time, 96

C California Air Resources Board (CARB), 283 Cam ground pistons, 260, 260f Cam-phasing, 224–225 Camshaft bore, 179–180 Camshaft lift, 202 Camshafts, 3, 4f, 10, 10f, 26, 26f, 245, 245f advanced, 204 bearings, 205, 205f, 257, 257f duration of, 203 journals, 208, 257 lobe separation angle, 203 lobes of, 202 retarded, 204 valvetrain and, 201–205, 201f, 202f Cam-shifting, 226

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index Carbon monoxide (CO), 98 Carbon steel, 120 Case hardening, 125 Cast aluminum, 123 Casting, 123 pressurizing with air or water, 126 Cast iron, 119–120, 123 Catalytic converters, 161–162, 161f problems, 162–163 C-class oil, 68 Central port fuel injection (CPFI) system, 94 Ceramics, 122 Cetane number, 101 Chain-driven systems, 220 Chamber-in-piston, 191–192 Channeling, 184 Chemical energy, conversion of, 28 Chevy Volt, 285, 286f, 294 Chrysler, “Hemi” V-style engine, 223 Clamps, 164–165 Clean Air Act of 1990, 272, 273 Clean Fuel Fleet program, 273 Clearance ramps, 203, 204f Closed loop system, 275 Clutch, 4, 5f, 30, 88, 244 Cohesion agents, 67 Coil, 36 Coil-on-plug (COP) systems, 96 Coke, 119 Cold cranking amperage (CCA), 63 Combustion, 2, 111–115 abnormal, 113 energy conversion during, 28 expansion controls, 260–261 issues, 113 process, 194–197 Combustion chamber, 2, 3f chamber-in-piston, 191–192 designs, 190–194 fast burn, 192 hemispherical chamber, 191 pentroof chamber, 191 sealing, 107–111 stratified-charge chambers, 193–194 swirl chamber, 191 tumble port, 192–193 wedge chamber, 190 Component remanufacturing facilities, 19–20

Composites, 122 Compressed natural gas (CNG) vehicles, 278–282 cylinder safety, 278–280 Honda Civic GX, 283–284 layout of, 278, 279f operation of, 281–282 safety, 280–281 Compressibility, 30 Compression-ignition (CI) engine, 36 Compression ratio, 42–43, 43f calculating, 44 Compressions rings, 266 Compression stroke, 32, 33f Compressor wheel, 151 Computer numerically controlled (CNC) equipment, 17, 18f Conformability, bearing materials, 252 Connecting rod–bearing journals, 241 Connecting rod bearings, 253–255 Connecting rods, 3, 3f, 23, 268–269, 269f Continuously variable transmission (CVT), 283, 289 Converter, 289 Coolant, 6, 76–78 flow, 85–86 Coolant recovery system, 80 Cooling fans, 88–90 Cooling systems, 6, 76–94 components of, 76 coolant, 76–78, 85–86 cooling fans, 88–90 heater core, 81, 82f hoses, 82 radiator, 78–81 reverse-flow, 86–87 thermostat, 82, 84, 84f, 85 warning indicators, 90–94. See also Warning indicators water pump, 82, 83f Core engine, 19 Core plugs, 239 Corrosion inhibitors, 66 Corrosion resistance, bearing materials, 252 Counterweights, crankshaft, 244 Cracks, 125 common causes for, 125 detecting, 125–126 Crankshaft, 23, 24, 24f, 240–245 construction, 244–245

315

counterweights, 244 fillets, 243–244 journal, 269 oil holes, 243 rotation, direction of, 42 splayed, 241, 242f throw, 42, 42f, 241 Crate engines, 168, 247 Crossflow radiators, 79, 79f Crude oil, 98 Cycle, 31 Cylinder block, 234. See also Engine block lubrication and cooling, 237–238 Cylinder bores, 239 Cylinder head gaskets, 131–133 Cylinder heads, 9–10, 26f, 177–198 component relationships, 189–190 intake and exhaust ports, 179 valves, 180–189. See also Valves Cylinders, 2 arrangement of, 34–35 number of, 34 Cylinder wall wear, 108–109

D Daimler-Chrysler, 69 Daimler, Gottlieb, 12 Damper spring, 213f Dedicated alternative fuel vehicles, 273 Detergents, 66, 101 Detonation, 43, 99, 113, 114, 195–196, 196f Diesel engine, 50–51 Diesel engine oils, 68 Diesel fuel, 101–102 Diesel pistons, 265, 266f Diesel, Rudolf, 50 Differential assembly, 168 Dispersants, 66 Displacement, of engine, 40–42 calculating, 41–42 Distributor, 221, 222f Distributor-ignition (DI) systems, 96 Downflow radiators, 79, 79f Dual-mode harmonic balancer, 246f Dual overhead camshaft (DOHC), 36, 37f, 222 Dual parallel system, 287

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316

Index

Dual springs, 212 Dual VVT-i (Dual Variable Valve Timing with Intelligence), 228 Duration, of camshaft, 203

E E85, 276–278, 277f, 278f Eddy currents, 192 Efficiency, 46–49 mechanical, 46 thermal, 48 volumetric, 47 Electrical energy, conversion of, 28 Electric motors, 289 Electric vehicles (EVs), 284–286 Electrolysis, 76 Electromagnets, 64, 125, 187 Electronically Controlled Continuously Variable Transmission (ECCVT), 293 Electronic-ignition (EI) systems, 96 Embedability, bearing materials, 252 Emission control system, 97–98 Emissions, credits, 283 End gases, 194 Energy conversion, 28 heat, 48 molecular, 30 types of, 28 and work, 27–28 Engine block, 11–12, 11f construction, 234–240 Engine coolant temperature (ECT) sensor, 88 Engine cradle, 168, 169f Engine manifold vacuum, 149 Engine mounts, 170–172, 171f types of, 172 Engine operation, 2–5, 31–33 automotive fuels, 98–102 cooling systems, 76–94. See also Cooling systems engine function, 4–5 engine location, 4 fuel system, 94–102 lubrication systems, 65–76. See also Lubrication systems principles, 27–29 starting system, 60–65 systems, 59–103

theory of, 22–56 transversely mounted engine, 4, 4f Engine performance, 7–9, 8f factors affecting, 105–116 Engines. See also Cylinder block; Engine operation adhesives, sealants, and liquid gasket maker, 138–139 air cleaner/filter, 143–146 bearings, 25 breathing, 6–7 classifications, 34–38 components of, 23–26 configurations, 168–170 definition of, 27 designs, 49–52 diesel, 50–51 displacement, 40–42 efficiency, 46–49 engine rebuild facilities, 17–18 fasteners, 126–131 function, 4–5 gaskets, 131–137 identification, 52–55 location, 4 long block, 233 longitudinally mounted, 169 manifold vacuum, 149 manufacturing processes for, 122–126 materials, 119–122 measurements, 42–49 mounts, 170–172, 171f multivalve, 197, 197f noises, 115–116 oil, 66–70 operating systems, 59–103 rebuild facilities, 17–18 remanufactured, 168, 172–175 remanufacturing facilities, 19–20 repair and rebuilding industry, 15–20 repair and replacement specialty facilities, 18 requirements for, 60 seals, 137 short block, 233 stratified charge, 52 transverse mounted, 168, 169f treatment methods, 124–125 two-stroke, 49–50 undersquare, 40 vacuum, 149 valves, 3, 3f

valvetrain types, 36 vibration, 38–40 Environmental Protection Agency (EPA), 272, 276, 283 Erosion, metal, 184, 185f Ethanol, 100 Exhaust gas recirculation (EGR) system, 147, 225 Exhaust manifold, 7, 159–161, 160f Exhaust manifold gaskets, 135 Exhaust stroke, 32, 33f Exhaust system catalytic converters, 161–162, 161f clamps, brackets, and hangers, 164–165 components, 159–163 exhaust manifold, 159–161, 160f exhaust pipe and seal, 161 heat shields, 164 mufflers, 163–165 resonator, 164 tailpipe, 164 Expansion controls, 260–261

F Face, valves, 180 Fast burn combustion chamber, 192 Fasteners, 126–131 liquid thread lockers, 130–131 torque, 127 torque-to-yield, 128–130 Fatigue resistance, bearing materials, 252 Ferrous metals, 119 Fiat’s MultiAir, 228 Fillet, 182 Fire ring, 133 Flexible fuel vehicles (FFVs), 276–278, 277f, 278f Flexplate, 60 Flywheel, 246–247, 247f. See also Flexplate Foam casting process, 235 Followers, 26, 124, 206, 208, 209 Ford, 69 Forging, 123–124 Free-wheeling engine, 184 Freeze plugs, 239 Friction, 29 Front main seal, 137 Fuel, 111–115 alternative, use of, 273 automotive, 98–102 diesel, 101–102

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Index octane rating of, 98, 111–112, 112f source, nonreplenishable, 195 volatility, 99–100 Fuel cell electric vehicles (FCEVs), 295 Fuel economy, 1, 5, 49, 52, 69, 283, 286, 287, 294 Fuel injection, 38 Fuel injection systems types, 38 Fuel system, 94–98 emission control system, 97–98 ignition system, 96–97 Full-filtration system, 73 Full-service repair facilities, 15–17

G Gases, behavior of, 30 Gaskets, 119, 131–137 cylinder head, 131–133 exhaust manifold, 135 intake manifold, 133–135 miscellaneous, 136–137 oil pan, 136 valve cover, 135–136 Gasoline, 27, 98 additives, 100–101 Gasoline direct injection (GDI) systems, 38, 94, 265, 266f Gasoline engine, 290. See also Engines Gas-to-liquid (GTL), 101 Gauge sending units, 90–91 Gear-driven systems, 223–224 General Motors, 69 electric car of, 284 engines, 155, 235 Geometry, rocker arms, 210–213, 211f Global Engine Manufacturing Alliance LLC (GEMA), 19 Glow plugs, 50 GM VVT, 225–226 Grade marks, 127 Grade, of bolt, 127 Gray cast iron, 119 Green ethylene glycol (EG) coolant, 77 Gross horsepower, 45

H Hangers, 164–165 Hard gaskets, 131 Harmonic balancers, 245, 246f HD-5 LPG, 273

Head gasket, 6, 6f, 86 damage, 110–111 Head, valves, 180 Heat energy, 48 Heater core, 81, 82f Heat quantity, 48 Hemispherical combustion chamber, 191 Honda Civic GX CNG vehicles, 283–284 Honda VTEC, 226–227 Honing, 239 Horsepower, 5, 27, 44–46, 45f brake, 45 gross, 45 indicated, 45 net, 45 Hoses, 82 Hybrid electric vehicles (HEV), 28, 286–287 Atkinson-cycle engine, 290–291 components, 289–290 gasoline engine, 290 Miller-cycle engine, 292 operation, 287–294 Toyota Prius, 292–294 Hydraulic lifter, 206, 207, 207f Hydraulic oil pressure, 228 Hydrocarbons (HC), 98 Hypereutectic casting, 265

I Ignition system, 96–97 types, 36–37 Indicated horsepower, 45 Inertia, 29 Inlet check valve, 74 Intake air temperature (IAT) sensor, 143, 143f, 144 Intake manifold, 6, 7f, 146–147 tuning, 147–149 Intake manifold gaskets, 133–135 Intake stroke, 32, 33f Intake system air cleaner/filter, 143–146 intake manifold, 146–149 turbochargers, 150–155 vacuum controls, 149–150 Integral valve seats, 186 Intercoolers, 153–154 Interference engine, 184, 219 Internal combustion engine (ICE), 1, 23 International Lubricant Standardization and Approval Committee (ILSAC), 68

317

Inverter, 289 Iron, 119 nodular, 120

J Japanese Automobile Standards Organization (JASO), 69 Jet valves, 74 Journals, 11 bearing, 39 camshaft, 208, 257 connecting rod–bearing, 241 crankshaft, 269 rod, 25, 241

K Kettering, Charles F., 61 Kinetic energy, 28 Knock sensor (KS), 99, 114, 115f

L Law of conservation of energy, 27 Lenoir, Jean-Joseph, 12 License plates, 33 Lifter bores, 245 Lifters, 206–208 hydraulic, 206, 207, 207f pump-up, 207 roller, 206, 206f solid, 206 Lift systems and variable valve timing, 226–230 Lip seal, 137 Liquefied petroleum gas (LPG), 273, 274 Liquid gasket maker, 138–139 Liquids, behavior of, 30 Liquid thread lockers, 130–131 Lobes, camshaft, 202 Lobe separation angle, 203 Locating tab, 254 Long blocks, 233, 247 Longitudinally mounted engine, 169 L-terminals, 62, 63f Lubrication systems, 6, 65–76 cylinder block, 237–238 engine oil, 66–70 oil coolers, 74 oil filter, 72–74 oil flow, 74–76 oil pumps, 71–72 synthetic oils, 70–71 warning indicators, 90–94

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

318

Index

M M85, 276–277 Machine shop, 17–18 Machining, 124 Magnaflux, 126 Magne Charge inductive charger, 285 Magnesium, 120 Magnetic fluorescent, 126 Magnetic particle inspection (MPI), 125–126 Main-bearing journals, 241 Main bearings, 254 Main bore, 240 Main caps, 240 Main journals, 11, 25, 243 Major thrust surface, 262 Manifold absolute pressure (MAP), 94, 149 Margin, valves, 181 Mass airflow (MAF) sensor, 94, 95f, 143 Mechanical efficiency, 46 Mechanical energy, conversion of, 28–29 Message center, 93–94 Metal erosion, 184, 185f Metallurgy, 119 powder, 124 Metals ferrous, 119 nonferrous, 119 Methanol, 276–277 Micron, 73 Mid-mounted engine, 170 Miller-cycle engine, 292 Minor thrust surface, 262 Misfire, 108, 115, 196–197 Molecular energy, 30 Momentum, 29 Motor mounts, 4, 168 Motor octane number (MON ), 98 Mufflers, 163–165 Multipoint fuel injection (MPFI) systems, 38, 94 Multivalve engines, 197, 197f

N Net horsepower, 45 Newton’s Laws of Motion, 29 first law, 29 friction, 29 inertia, 29 momentum, 29 second law, 29 third law, 29

Nodular iron, 120 Noises, of engine, 115–116 Nonferrous metals, 119 Nucleate boiling, 78

O Octane number, 98–99 MON, 98 RON, 98 Octane rating, 98, 111–112, 112f Offset pin, 262, 263f Off-square seating, 185, 186 Oil breakdown, 70 Oil clearances, bearings, 255–256 Oil coking, 154 Oil consumption, 108 Oil control rings, 267 Oil cooler, 74 Oil filter, 72–74 Oil galleries, 237 Oil grooves, 254 Oil holes, 254 Oil pan gaskets, 136 Oil pumps, 6, 7f, 71–72 Oil sludge, 71 Open loop system, 275 Organic Additive Technology (OAT) corrosion inhibitors, 77 Otto, Nicholas, 12 Overhead camshaft (OHC) engines, 9, 9f, 36 valvetrain designs, 208–209 Overhead valve (OHV) engines, 36, 36f, 209 Oversize bearings, 256 Oxidation, 66 Oxidation inhibitors, 101 Oxides of nitrogen, 98

P Parallel system, 287 Pedestal-mounted rocker arms, 210 Penetrant dye, 126 Pentroof combustion chamber, 191 Piezoresistive sensor, 91 Pinging, 112. See also Detonation Piston, 2, 3f designs and construction, 263–266 tapered, 260 Piston pin, 262 Piston pin offset, 262, 262f

Piston rings, 25, 266–268 oversize rings, 268 ring materials, 268 Pistons, 257–263 cam ground, 260, 260f parts of, 258 Piston speed, 263 Pitch, 127 Plastics, 121–122 Plug-In Hybrid Electric Vehicle (PHEV), 294 Pogue carburetor, 164 Pole shoes, 64 Poppet valves, 180, 181f Positive displacement pumps, 71 Post terminals, 62, 63f Potential energy, 28 Pour point depressants, 66 Powder metallurgy, 124 Power, 45 Power splitting device, 289 Power stroke, 32, 33f Powertrain control module (PCM), 2, 23, 38, 88, 94, 95, 142, 147, 149. See also Warning indicators atmospheric pressure and, 31 control of cooling fans by, 88 control of fuel delivery by, 94, 96, 277 ignition system and, 96–97 knock sensor, 99 MAP sensor, 94 message center, 93–94 vacuum solenoid, 149, 150f Powertrains, 2 Preignition, 43, 112–114, 114f, 195, 196f Pressure, 30–31 Propane vehicles, 273–276 Propylene glycol (PG) coolant, 77 Prove-out circuit, 93, 93f Pumping loss, 47, 291 Pump-up, lifters, 207 Pushrods, 9, 209

Q Quenching, 190

R Radiator, 78–81 Rear main seal, 137 Rear-mounted muffler, 164 Rebuild facilities, engine, 17–18 Reciprocating, 32 Reed value, 49

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Index Regenerative braking, 287 Reid vapor pressure (RVP), 112 Remanufactured engines, 168, 172–175 Repair and replacement specialty facilities, engine, 18 Research octane number (RON), 98 Resonator, 164 Retarded camshafts, 204 Retrofitted alternative fuel vehicles, 273 Reverse-flow cooling systems, 86–87, 87f Reversion, 204, 205 Ring gear, 60 Rings wear, 108–109 Rocker arm ratio, 210 Rocker arms, 209–213 geometry, 210–213, 211f pedestal-mounted, 210 shaft-mounted, 210 stud-mounted, 210 Rod bearings, 255 Rod cap, 269 Rod journals, 25, 241 Roller lifter, 206, 206f Room-temperature vulcanizing (RTV), 138 Roots-type supercharger, 156 Rotary valve, 49 Rust inhibitors, 66

S Saddles, 74 S-class oil, 68 Sealants, 131, 138 Seals, 119, 137 front main, 137 lip, 137 rear main, 137 Sequential fuel injection (SFI) systems, 38 Series system, 287 Service sleeves, 137 Shaft-mounted rocker arms, 210 Shock absorbers, 65, 172, 173f Short blocks, 233, 234f, 247 Shot peening, 125 Side terminals, 62, 63f Sintering, 124 Skin effect, 195 Smoke, 11, 105, 106f, 111f, 153, 179, 188, 189, 266 Society of Automotive Engineers (SAE), 42, 45, 67 Soft gaskets, 131 Solenoid, 229

Solid lifters, 206 Spark-ignition (SI) engine, 36 Spark knock. See Detonation Spark plugs, 106–107, 106f Splayed crankshaft, 241, 242f Squish area, 190 Stainless steel, 120 Stamping, 124 Starter motors, 64–65 Starting system, 60–65 battery, 62–64 components of, 60, 61f starter motors, 64–65 Steel, 120 carbon, 120 stainless, 120 tensile strength, 120 Stellite, 187 Stem necking, 185 Stratified-charge combustion chamber, 193–194 Stratified charge engine, 52, 52f, 53f Strip seals, 133 Stroke, 40, 41f Stud-mounted rocker arms, 210 Superchargers, 155–159 operation, 156–159 roots-type, 156 Super-Ultra-Low-Emission Vehicle (SULEV), 283, 284f Surface action, bearing materials, 252 Surface-to-volume (S/V) ratio, 190 Suspension cradle. See Engine cradle Swirl combustion chamber, 191 Synthetic oils, 70–71

T Tailpipe, 164 Tapered piston, 260 Technical service bulletins (TSBs), 230 Temperature, 30 Tempering, 124 Tensile strength, 120 Tetraethyl (TEL) lead, 100 Thermal efficiency, 48 Thermal energy, conversion of, 28 Thermistor, 90 Thermodynamics, 27 Thermostat, 6, 6f, 82, 84, 84f, 85 Thread depth, 127 Throttle, 31, 40, 47, 94, 141–144, 149, 150, 177, 197, 225, 226, 273, 275, 287, 294

319

Thrust bearings, 255 Timing chain guides, 220 Timing chain tensioner, 220 Timing mechanisms, 10–11, 217–231 belt-driven systems, 221–223 chain-driven systems, 220 gear-driven systems, 223–224 lift systems, 226–230 valve timing systems, 217–219 variable valve lift (cam-shifting), 226 variable valve timing systems, 224–230 Tipping, 185, 185f Titanium, 121 Top dead center (TDC), 32 Top terminals, 62, 63f Torque, 27, 44–46, 44f, 45f Torque converter, 246 Torque-to-yield bolt, 128–130 Torsional vibration, 245 Toyota Prius, 292–294, 293f Toyota VVT, 227–228 Transmission, 25 Transverse mounted engine, 4, 4f, 35, 168, 169f Tumble port combustion chamber, 192–193 Turbine wheel, 150, 151f Turbo boost, 151 Turbochargers, 150–155 basic operation, 150–152 boost pressure control, 152 scheduled maintenance for, 154–155 turbocharger cooling, 153 turbo lag, 153 Turbo lag, 153 Turbulence, 190 Two-stroke engines, 49–50

U Undersize bearings, 256 Undersquare, engines, 40 Unified National Fine-thread, 127 U-type clamp, 164, 165f

V Vacuum, 30–31 basics, 149 controls, 149–150 solenoids, 149 Valley pans, 133 Valve cover gaskets, 135–136 Valve float, 183 Valve guides, 188

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Index

Valve job, 190 Valve lift, 202 Valve overlap, 32, 203 Valves, 180–189. See also Valvetrains aluminized, 183 burned, 183–184 deposits on, 183 determining malfunctions of, 183–186 float, 183 machine, 16f poppet, 180, 181f seals, 188–189 stem, 181 Valve seat inserts, 186, 187f Valve seat recession, 187, 187f Valve seats, 186–188 inserts, 186 integral, 186 recession, 187, 187f Valve springs, 3, 190, 212 functions of, 212 retainers and rotators, 214, 214f Valve stem wear, 186 Valve timing, 3 failures, 10f mechanism, 217, 218f systems, 217–219 Valvetrains, 9, 9f. See also Valves camshafts and, 201–205, 201f, 202f

components, 201 OHC, designs, 208–209 types, 36 Valve wear, 109–110 Variable cylinder displacement, 228 Variable-length intake manifold, 147, 148f Variable-rate springs, 212, 213f Variable timing and lift electronic control (VTEC) system, 226 Variable valve lift (cam-shifting), 226 Variable valve timing (VVT) system, 108, 224–226 cam-phasing, 224–225 and lift systems, 226–230 Vehicle identification number (VIN), 52, 53f, 54f Vehicles alternative fuel and advanced technology, 272–295 compressed natural gas, 278–282 E85 and flexible fuel, 276–278, 277f, 278f electric, 284–286 fuel cell, 295 hybrid electric, 286–287 operation of, 281–282 plug-in hybrid electric, 294 propane, 273–276, 274f, 275f safety, 280–281

V6 engines, 222, 241, 258f V8 engines, 86, 229 Vibrations engine, 38–40 torsional, 245 Viscosity, 70 Viscosity index, 70 Viscosity index improver, 66 Volatility, of fuel, 99–100, 112 Volumetric efficiency (VE), 47 V-type engine design, 35, 35f

W Warm-up converters, 162, 162f Warning indicators, 90–94 gauge sending units, 90–91 message center, 93–94 warning lights, 91–93 Warning lights, 91–93, 92f, 93f Wastegate diaphragm, 152, 152f Waste spark, 96 Water pump, 82, 83f Wedge combustion chamber, 190 Wrist pin, 25

Z Zero-emission vehicles (ZEV), 284 Zero lash, 206

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SHOP MANUAL For Automotive Engine Repair & Rebuilding

SIXTH EDITION

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

SHOP MANUAL For Automotive Engine Repair & Rebuilding

SIXTH EDITION Chris Hadfield Director, Minnesota Transportation Center of Excellence

Randy Nussler South Puget Sound Community College & New Market Skills Center

Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Today’s Technician: Automotive Engine Repair & Rebuilding, Sixth Edition Chris Hadfield Randy Nussler SVP, GM Skills & Global Product Management: Jonathan Lau Product Director: Matthew Seeley Senior Product Manager: Katie McGuire Senior Director, Development: Marah Bellegarde Senior Product Development Manager: Larry Main Senior Content Developer: Mary Clyne Product Assistant: Mara Ciacelli Vice President, Marketing Services: Jennifer Ann Baker Associate Marketing Manager: Andrew Ouimet Senior Production Director: Wendy Troeger Production Director: Andrew Crouth Senior Content Project Manager: Cheri Plasse

© 2018, 2014 Cengage Learning ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced or distributed in any form or by any means, except as permitted by U.S. copyright law, without the prior written permission of the copyright owner. For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, 1-800-354-9706

For permission to use material from this text or product, submit all requests online at www.cengage.com/permissions. Further permissions questions can be e-mailed to [email protected]

Library of Congress Control Number: 2017930372 Shop Manual ISBN: 978-1-305-95812-8 Package ISBN: 978-1-305-95813-5 Cengage Learning 20 Channel Center Street Boston, MA 02210 USA

Senior Art Director: Jack Pendleton Production Service/Composition: SPi Global Cover image(s): Umberto Shtanzman/ Shutterstock.com

Cengage Learning is a leading provider of customized learning solutions with employees residing in nearly 40 different countries and sales in more than 125 countries around the world. Find your local representative at www.cengage.com. Cengage Learning products are represented in Canada by Nelson Education, Ltd. To learn more about Cengage Learning, visit www.cengage.com Purchase any of our products at your local college store or at our preferred online store www.cengagebrain.com

Notice to the Reader Publisher does not warrant or guarantee any of the products described herein or perform any independent analysis in connection with any of the product information contained herein. Publisher does not assume, and expressly disclaims, any obligation to obtain and include information other than that provided to it by the manufacturer. The reader is expressly warned to consider and adopt all safety precautions that might be indicated by the activities described herein and to avoid all potential hazards. By following the instructions contained herein, the reader willingly assumes all risks in connection with such instructions. The publisher makes no representations or warranties of any kind, including but not limited to, the warranties of fitness for particular purpose or merchantability, nor are any such representations implied with respect to the material set forth herein, and the publisher takes no responsibility with respect to such material. The publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or part, from the readers’ use of, or reliance upon, this material.

Printed in the United States of America Print Number: 01  Print Year: 2017

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CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii CHAPTER 1  Safety and Shop Practices . . . . . . . . . . . . . . . . . . . . . . . . 1 Terms to Know 1 • Introduction 2 • Personal Safety 2 • Lifting and Carrying 6 • Hand Tool Safety 6 • Power Tool Safety 7 • Compressed Air Equipment Safety 10 • Lift Safety 10 • Jack and Jack Stand Safety 13 • Engine Lift Safety 15 • Cleaning Equipment Safety 16 • Hazardous Waste 19 • Vehicle Operation 20 • Work Area Safety 21 • Hybrid Vehicle High-Voltage Safety 23 • ASE-Style Review Questions 24 • ASE Challenge Questions 25 CHAPTER 2  Engine Rebuilding Tools and Skills . . . . . . . . . . . . . . . . . 39 Terms to Know 39 • Introduction 40 • Units of Measure 40 • Engine Diagnostic Tools 42 • Exhaust Gas Analyzers 52 • Engine Analyzer 53 • Engine Measuring Tools 54 • Special Hand Tools 68 • Engine and Chassis Dynamometers 72 • Special Reconditioning Tools and Equipment 72 • Working as a Professional Technician 85 • Service Information 93 • ASE-Style Review Questions 99 CHAPTER 3  Basic Testing, Initial Inspection, and

Service Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Terms to Know 117 • Introduction 117 • Proper Vehicle Care 118 • Writing a Service Repair Order 119 • Test-Driving for Engine Concerns 119 • Identifying the Area of Concern 121 • ASE-Style Review Questions 124 • ASE Challenge Questions 125

CHAPTER 4  Diagnosing and Servicing Engine

Operating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

Terms to Know 135 • Introduction 136 • Battery Safety 136 • Battery Testing 136 • Battery Testing Series 138 • Starting System Tests and Service 142 • Lubrication System Testing and Service 151 • Cooling System Testing and Service 161 • Gallery and Casting Plugs 174 • Leak Diagnosis 176 • Warning Systems Diagnosis 184 • ASE-Style Review Questions 188 • ASE Challenge Questions 189

CHAPTER 5  Diagnosing Engine Performance Concerns . . . . . . . . . . 227 Terms to Know 227 • Introduction 228 • Spark Plug Evaluation and Power Balance Testing 228 • Spark Plugs 228 • Power Balance Testing 233 • Exhaust Gas Analyzers 235 • Engine Smoking 236 • Improper Combustion 242 • Compression Testing 244 • Wet Compression Test 246 • Running Compression Test 247 • Cylinder Leakage Testing 249 • Engine Noise Diagnosis 255 • ASE-Style Review Questions 258 • ASE Challenge Questions 259

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vi

CHAPTER 6  Repair and Replacement of Engine Fasteners,

Gaskets, and Seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

Terms to Know 275 • Introduction 275 • Thread Repair 275 • Gasket Installation 284 • Cylinder Head Gasket Installation 284 • Oil Pan Gasket Installation 285 • Valve Cover Gasket Replacement 285 • Seal Installation 287 • Using Adhesives, Sealants, and Liquid Gasket Makers 288 • ASE-Style Review Questions 289 • ASE Challenge Questions 290

CHAPTER 7  Intake and Exhaust System Diagnosis and Service . . . . 299 Terms to Know 299 • Introduction 299 • Air Cleaner Service 300 • Vacuum System Diagnosis and Troubleshooting 302 • Vacuum Tests 304 • Intake Manifold Service 305 • Exhaust System Service 311 • Turbocharger Diagnosis 317 • Supercharger Diagnosis and Service 324 • ASE-Style Review Questions 327 • ASE Challenge Questions 328 CHAPTER 8  Engine Removal, Engine Swap, and

Engine Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

Terms to Know 341 • Introduction 341 • Preparing the Engine for Removal 341 • Removing the Engine 347 • Typical Procedure for RWD Engine Removal 351 • Installing a Remanufactured Engine 353 • Installing the Engine 361 • Engine Start-Up and Break-In 365 • ASE-Style Review Questions 369 • ASE Challenge Questions 370

CHAPTER 9  Cylinder Head Disassembly, Inspection,

and Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381

Terms to Know 381 • Introduction 381 • Disassembling the Cylinder Head 387 • Valve Inspection 394 • Cylinder Head Inspection 397 • Machine Shop Services 403 • Straightening Aluminum Cylinder Heads 404 • Resurfacing Cylinder Heads 405 • Valve Guide Repair 406 • Replacing Valve Seats 409 • Refinishing Valves and Valve Seats 411 • ASE-Style Review Questions 422 • ASE Challenge Questions 423

CHAPTER 10  Valvetrain Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 Terms to Know 441 • Introduction 441 • Inspecting and Servicing the Valvetrain 442 • Inspecting and Servicing Valvetrain Components, OHV Engine 447 • Replacing Rocker ARM Studs 450 • Cylinder Head Reassembly 457 • Valve Adjustment 463 • Adjusting Mechanical Followers with Shims 466 • Adjusting Valve Clearance Using Adjustable Rocker Arms 467 • On-Car Service 472 • Valve Spring Replacement 475 • ASE-Style Review Questions 476 • ASE Challenge Questions 477 CHAPTER 11  Timing Mechanism Service . . . . . . . . . . . . . . . . . . . . . 495 Terms to Know 495 • Introduction 495 • Symptoms of a Worn Timing Mechanism 496 • Symptoms of a Jumped or Broken Timing Mechanism 497 • Timing Chain Inspection 498 • Timing Belt Inspection 499 • Timing Gear Inspection 500 • Sprocket Inspection 501 • Tensioner Inspection 501 • Timing Chain Guide Inspection 502 • Reuse Versus Replacement Decisions 502 • Timing Mechanism Replacement 503 • Timing Chain Replacement on OHC Engines 504 • Timing Belt Replacement 507 • Timing Chain or Gear Replacement on Camshaft-In-The-Block Engines 512 • Timing Chain Replacement on Engines with OHC and Balance Shafts 513 • Timing Chain Replacement on Engines with VVT Systems 515 • ASE-Style Review Questions 521 • ASE Challenge Questions 522

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Chapter 12  Inspecting, Disassembling, and Servicing the Cylinder Block Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533 Terms to Know 533 • Introduction 533 • Engine Preparation 534 • Cylinder Head Removal 535 • Timing Mechanism Disassembly 536 • Engine Block Disassembly 540 • Inspecting the Cylinder Block 544 • Inspecting the Crankshaft 551 • Inspecting the Harmonic Balancer and Flywheel 554 • Servicing the Cylinder Block Assembly 555 • Camshaft and Balance Shaft Bearing Service 564 • Reconditioning Crankshafts 567 • Installing Oil Gallery Plugs and Core Plugs 569 • ASE-Style Review Questions 571 • ASE Challenge Questions 572

CHAPTER 13  Short Block Component Service and

Engine Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587

Terms to Know 587 • Introduction 587 • Inspecting Crankshaft Bearings 588 • Inspecting the Pistons and Connecting Rods 591 • Piston Assembly Service 603 • Engine Block Preparation 612 • Installing the Main Bearings and Crankshaft 616 • Installing the Pistons and the Connecting Rods 623 • Completing the Block Assembly 625 • Valve Timing and Installing Valvetrain Components 628 • Checking and Adjusting Valve Clearance 630 • Completing the Engine Assembly 630 • ASE-Style Review Questions 637 • ASE Challenge Questions 638

CHAPTER 14  Alternative Fuel and Advanced Technology

Vehicle Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659

Terms to Know 659 • Introduction 659 • Servicing Propane-Fueled Engines 659 • Servicing CNG Vehicles 660 • Servicing Hybrid Electric Vehicles 663 • Servicing the Toyota Prius 664 • Cooling System Service 667 • Servicing the Honda Civic Hybrid 668 • HEV Warranties 669 • ASE-Style Review Questions 670 • ASE Challenge Questions 671

APPENDIX A  ASE Practice Exam . . . . . . . . . . . . . . . . . . . . . . . . . . . 681 APPENDIX B  Special Tools Suppliers . . . . . . . . . . . . . . . . . . . . . . . . 686 APPENDIX C  Manufacturers’ Service Information Centers . . . . . . . 687 APPENDIX D  Metric Conversion Charts . . . . . . . . . . . . . . . . . . . . . 688 APPENDIX E   Engine Specifications Chart . . . . . . . . . . . . . . . . . . . 689

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 702

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PHOTO SEQUENCES



viii

1. Typical Procedure for Lifting a Vehicle on a Hoist 2. Typical Procedure for Lifting a Vehicle on a Drive-On Hoist 3. Typical Procedure for Reading a Dial Caliper 4. Typical Procedure for Reading a Micrometer 5. Starter R 1 R 6. Typical Procedure for Disassembly and Inspection of Rotor-Type Oil Pump 7. Typical Procedure for Resetting the Engine Oil Life Indicator/Reminder 8. Typical Procedure for Changing Engine Oil 9. Cooling System Testing 10. Typical Procedure for Using a Scan Tool to Retrieve DTCs 11. Typical Procedure for Performing a Cranking Compression Test 12. Typical Procedure for Performing a Cylinder Leakage Test 13. Removing a Broken Bolt and Using a Tap 14. Replacing a Valve Cover Gasket 15. Typical Procedure for Removing and Replacing an Intake Manifold Gasket 16. Typical Procedure for Inspecting Turbochargers and Testing Boost Pressure 17. Typical Procedure for FWD Engine Removal 18. Typical Procedure for RWD Engine Removal 19. Mounting the Engine on a Stand 20. Typical Procedure for Disassembling an OHC Cylinder Head 21. Typical Procedure for Grinding Valve Seats 22. Typical Procedure for Adjusting Valves 23. Replacing Valve Seals on the Vehicle 24. Typical Procedure for Replacing a Timing Belt on an OHC Engine 25. Typical Procedure for Replacing Timing Chains on a DOHC Engine with Balance Shafts 26. Typical Procedure for Checking Main Bore Alignment 27. Typical Procedure for Cylinder Honing 28. Typical Procedure for Checking Main Bearing Oil Clearances 29. Typical Procedure for Installing the Main Bearings and Crankshaft

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12 14 58 63 150 153 157 159 181 187 246 253 281 286 308 321 348 352 354 391 420 469 473 510 513 550 559 615 620

JOB SHEETS

1. Shop Safety Survey 2. Proper Handling of Hazardous Materials 3. Using Floor Jacks and Jack Stands 4. Lifting a Unibody Vehicle 5. Lifting a Body on Frame Vehicle 6. Identifying Engine Service Tools 7. Using Feeler Gauges 8. Reading Dial Calipers 9. Reading a Dial Indicator 10. Using an Outside Micrometer 11. Measuring Cylinder Wall Wear 12. Finding Service Information 13. Locating and Understanding Technical Service Bulletins 14. Engine Component Identification 15. Test-Drive, Basic Inspection, and Preparing for Service 16. Writing a Service Repair Order 17. Performing a Battery Test 18. Testing a Starter 19. Inspecting the Engine Oil 20. Performing an Oil and Filter Change 21. Oil Change Reminder/Indicator Reset 22. Oil Pump Inspection and Measurement 23. Oil Pressure Testing 24. Oil Leak Diagnosis 25. Testing an Oil Pressure Switch/Sensor and Circuit 26. Test, Drain, and Refill Coolant 27. Radiator Replacement 28. Diagnosing Cooling System Leaks 29. Replacing a Water Pump 30. Diagnosing and Replacing a Thermostat 31. Testing a Coolant Temperature Switch/Sensor Circuit 32. Engine Belt and System Inspection 33. Cooling System Fan Inspection 34. Using a Scan Tool to Retrieve Engine Codes 35. Diagnosing Engine Noises and Vibrations 36. Analyzing Spark Plugs and Performing a Power Balance Test 37. Oil and Coolant Consumption Diagnosis

27 31 33 35 37 101 103 105 107 109 111 113 115 127 129 131 191 193 195 197 199 201 203 205 207 209 211 213 215 217 219 221 223 225 261 263 267

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x

38. Performing Compression Tests 39. Performing a Running Compression Test 40. Performing a Cylinder Leakage Test 41. Identifying Engine Fasteners and Torque Specifications 42. Loosening a Rusted Fastener 43. Replacing an Oil Pan Gasket 44. Identifying Engine Materials 45. Inspect and Service Air Cleaner 46. Diagnosing Vacuum Leaks 47. Exhaust System Inspection and Test 48. Turbocharger System Inspection 49. Testing Boost Pressure 50. Engine Removal FWD 51. Engine Removal RWD 52. Engine Installation 53. Inspect, Remove, and Replace Engine Mounts 54. Removing the Harmonic Balancer and Pulley 55. Cylinder Head Removal 56. Cylinder Head Disassembly 57. Cylinder Head Crack Detection 58. Measuring Cylinder Head Warpage 59. Measuring Valve-Stem-To-Guide Clearance 60. Valve Seat Grinding 61. Reconditioning Valves 62. Valve Stem Seal Replacement on an Assembled Engine 63. Valve Spring Inspection 64. Inspecting the Camshaft 65. Inspecting the Lifters (Lash Adjusters) 66. Inspecting the Pushrods and Rocker Arms 67. Checking and Adjusting Valve Clearance 68. Reassembling the Cylinder Head 69. Inspecting, Removing, and Replacing a Timing Chain or Belt 70. Inspecting the Variable Valvetrain Timing Components 71. OHV Valvetrain Timing 72. SOHC Valvetrain Timing 73. DOHC Variable Valve Timing 74. Disassembling an Engine Block 75. Engine Block Crack Detection 76. Measuring Deck Warpage 77. Cylinder Block Thread Cleaning 78. Inspecting and Measuring the Cylinder Walls 79. Inspecting and Measuring Main Bearing Bore Alignment Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

269 271 273 291 293 295 297 331 333 335 337 339 373 375 377 379 425 427 429 431 433 435 437 439 479 481 483 485 487 489 491 523 525 527 529 531 573 577 579 581 583 585

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80. Inspecting the Pistons and Connecting Rods 81. Inspecting the Bearing Wear Patterns 82. Installing the Piston Rings 83. Installing the Camshaft 84. Installing the Main Bearings and the Crankshaft 85. Installing the Pistons and the Connecting Rods 86. Servicing an LPG or CNG Vehicle 87. Researching an Advanced Technology Vehicle 88. Disabling the High-Voltage Battery Pack on a Hybrid Electric Vehicle 89. Performing a Compression Test on a Hybrid Electric Vehicle

639 643 645 649 651 655 673 675 677 679

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PREFACE

Thanks to the support the Today’s TechnicianTM series has received from those who teach automotive technology, Cengage Learning, the leader in automotive related textbooks, is able to live up to its promise to provide new editions of the series every few years. By revising this series on a regular basis, we can respond to changes in the industry, changes in technology, changes in the certification process, and to the ever-changing needs of those who teach automotive technology. The Today’s TechnicianTM series features textbooks and digital learning solutions that cover all mechanical and electrical systems of automobiles and light trucks. The individual titles correspond to the ASE (National Institute for Automotive Service Excellence) certification areas and are specifically correlated to the 2016 standards for Automotive Service Technicians (AST), Master Automotive Service Technicians (MAST), and Maintenance and Light Repair (MLR). Additional titles include remedial skills and theories common to all of the certification areas and advanced or specific subject areas that reflect the latest technological trends, such as this updated title on engine repair. Today’s Technician: Automotive Engine Repair and Rebuilding, 6th edition, is designed to give students a chance to develop the same skills and gain the same knowledge that today’s successful technicians have. This edition also reflects the changes in the guidelines established by the National Automotive Technicians Education Foundation (NATEF). The purpose of NATEF is to evaluate technician training programs against standards developed by the automotive industry and recommend qualifying programs for certification (accreditation) by ASE. Programs can earn ASE certification upon NATEF’s recommendation. NATEF’s national standards reflect the skills that students must master. ASE certification through NATEF evaluation ensures that certified training programs meet or exceed industry-recognized, uniform standards of excellence. The technician of today and for the future must know the underlying theory of all automotive systems and be able to service and maintain those systems. Dividing the material into two volumes, a Classroom Manual and a Shop Manual, provides the reader with the information needed to begin a successful career as an automotive technician without interrupting the learning process by mixing cognitive and performance learning objectives into one volume. The design of Cengage’s Today’s TechnicianTM series was based on features that are known to promote improved student learning. The design was further enhanced by a careful study of survey results, in which the respondents were asked to value particular features. Some of these features can be found in other textbooks, while others are unique to this series. Each Classroom Manual contains the principles of operation for each system and subsystem. The Classroom Manual also contains discussions on design variations of key components used by the different vehicle manufacturers. It also looks into emerging technologies that will be standard or optional features in the near future. This volume is organized to build upon basic facts and theories. The primary objective of this volume is to allow the reader to gain an understanding of how each system and subsystem operates. This understanding is necessary to diagnose the complex automobiles of today and tomorrow. Although the basics contained in the Classroom Manual provide the knowledge needed for diagnostics, diagnostic procedures appear only in the Shop Manual. An understanding of the underlying theories is also a requirement for competence in the skill areas covered in the Shop Manual. xii

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A spiral-bound Shop Manual delivers hands-on learning experiences with ­step-by-step instructions for diagnostic and repair procedures. Photo Sequences are used to illustrate some of the common service procedures. Other common procedures are listed and are accompanied with fine line drawings and photos that allow the reader to visualize and conceptualize the finest details of the procedure. This volume also contains the reasons for performing the procedures, as well as when that particular service is appropriate. The two volumes are designed to be used together and are arranged in corresponding chapters. Not only are the chapters in the volumes linked together, the contents of the chapters are also linked. The linked content is indicated by marginal callouts that refer the reader to the chapter and page where the same topic is addressed in the companion volume. This valuable feature saves users the time and trouble of searching the index or table of contents to locate supporting information in the other volume. Instructors will find this feature especially helpful when planning the presentation of material and when making reading assignments. Both volumes contain clear and thoughtfully selected illustrations, many of which are original drawings or photos specially prepared for inclusion in this series. This means that the art is a vital part of each textbook and not merely inserted to increase the number of illustrations. The layout of Automotive Engine Repair & Rebuilding, 6th edition, is easy to follow and consistent with the Today’s TechnicianTM series. Complex systems are broken into easier-to-understand explanations. Industry standardized terms and vernacular are used and explained in the text. Jack Erjavec

HIGHLIGHTS OF THE NEW EDITION—CLASSROOM MANUAL The Classroom Manual for this edition of Today’s Technician: Automotive Engine Repair and Rebuilding includes updated coverage of the NATEF AST, MAST, and MLR tasks for engine repair and rebuilding. In addition to updated coverage of industry trends, new information has been added on: ■■ 0w16 oil ■■ Engine design changes for GDI (gas direct injection), ■■ EPDM belts ■■ Stretch belts ■■ Wet timing belts ■■ Flat plane crankshafts ■■ Cam phaser design, operation, and service ■■ Variable valve timing ■■ Variable lift ■■ Active fuel management ■■ Variable cylinder displacement

HIGHLIGHTS OF THE NEW EDITION—SHOP MANUAL Like all textbooks in the Today’s TechnicianTM series, the understanding acquired by reading the Classroom Manual is required for competence in the skill areas covered in the Shop Manual. Service information related to the topics covered in the Classroom Manual is included in this manual. In addition, several photo sequences are used to highlight typical service procedures and provide the student the opportunity to get a realistic idea Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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of a procedure. The purpose of these detailed photo sequences is to show students what to expect when they perform the same procedure. They can also provide a student with familiarity of a system or type of equipment they may not be able to perform at their school. To stress the importance of safe work habits, Chapter 1 covers safety issues and has been updated to include hybrid vehicle high-voltage safety. Included in this chapter are common shop hazards, safe shop practices, safety equipment, and the legislation concerning and the safe handling of hazardous materials and wastes. Chapter 2 covers special tools and procedures. Procedures include the use of engine condition and diagnostic test equipment, precision engine measuring tools and specialty measuring tools, along with engine reconditioning tools and equipment. The subsequent Shop Manual chapters synch up with those in the Classroom Manual, and the related content of each manual’s chapters is linked by use of page references in the margins. This allows the student to quickly cross-reference the theory with the practical. Redundancy between the Classroom Manual and the Shop Manual has been kept to a minimum; the only time theory is discussed again is if it is necessary to explain the diagnostic results or as an explanation of the symptom. Currently accepted service procedures are used as examples throughout the text. These procedures also served as the basis for the job sheets that are included in the textbook at the end of each chapter. Updated coverage in the Shop Manual addresses: ■■ Engine pre-oiling ■■ Engine break-in ■■ 500-mile service for newly rebuilt engines ■■ HEV service and safety ■■ Concerns related to improper oil service on hydraulically controlled systems

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CLASSROOM MANUAL Features of the Classroom Manual include the following:

CH AP TE R

3

THEORY O F ENGINE OPERATIO N

Cognitive Objectives

Upon comple tion

and review of this chapte r, you should Major engine understand component and be able s. Basic engine to describe: operation. compressio n ratio, eng Basic laws of ine efficiency horsepower physics involv , and engine ope ed with losses, mecha torque, horsepower ration. nical efficie ■ Eng ncy, and thermal effi ine classific ciency. ations accord the number ing ■ to The relation of cycles, the ship betwe cylinders, cyli number of en com ratio and eng nder arrange ine power out pression and valvetrai ment, ■ Mecha put. n type. nical, volum ■ The etri four-stroke effi cie ncies, and fac c, and thermal cycle theory ■ The tors . that affect eac different cyli h. nde r arra and the adv ngements ■ The antages of basic operati each. on of alterna ■ The engine des different valv tive igns, includ etrains used ing two-stroke modern eng diesel, and in ines. , stratified cha rge. ■ Eng ■ The interna ine measurem l component ent term s of a diesel bore and stro s such as engine and how they diff ke, displacem er from tho of a gas eng ent, se ine. Terms To Kn ow Autoignition temperature Engine bea Bore rings Potential ene Friction Bottom dea rgy d center (BD C) Preignition Fuel injectio Boyle’s law n Reciprocating Glo Brake horsep w plugs ower Reed valve Gross horsep Coil ower Rotary valv Horsepower Compressio e n-ignition (CI) engines Spark-ignition Hybrid electri (SI) engine c vehicle Compressio (HEV) Stroke n ratio Indicated hor Connecting The rmal efficie sepower rods ncy Internal com Crankshaft Thermodyn bustion eng amics ine Kinetic ene Cycle Top dead cen rgy ter (TDC) Law of con Detonation Torque servation of energy Displacement Transmission Mechanical Dual overhe Transverse-m efficiency ad cam ounted eng Net horsep (DOHC) ine ower Vacuum Overhead cam Engine Valve overlap (OHC) face Ov Efficiency ing erh Part ead valve (OH Volumetric V) effi cie ncy (VE) Piston rings Wrist pin

These objectives outline the chapter’s contents and identify what students should know and be able to do upon completion of the chapter. Each topic is divided into small units to promote easier understanding and learning.

■

■

■

Terms to Know List A list of key terms appears immediately after the Objectives. Students will see these terms discussed in the chapter. Definitions can also be found in the Glossary at the end of the manual.

256

Chapter 13

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Cross-References to the Shop Manual References to the appropriate page in the Shop Manual appear whenever necessary. Although the chapters of the two manuals are synchronized, material covered in other chapters of the Shop Manual may be fundamental to the topic discussed in the Classroom Manual.

Margin Notes The most important terms to know are highlighted and defined in the margin. Common trade jargon also appears in the margin and gives some of the common terms used for components. This helps students understand and speak the language of the trade, especially when conversing with an experienced technician.

indd 22

Bearing crown

A multipleFigure 13-10 ing. piece thrust bear

at the top e clearances ied. maintains clos Bearing crown re most of the loads are appl Figure 13-11 the bearing, whe and bottom of

2/16/17 7:15 AM

inch mm) to 0.002 ons inch (0.0203 cificati ge of 0.0008 acturer’s spe within the ran ck the manuf clearances fall ical clearances; always che t or oil bearing typ haf nks just t the cra These are r and protec g on. (0.0508 mm). en the you are workin They are designed to wea to contaminated oil. Wh s. for the engine r item. exposure cam bearing wea and a e and , are eag rod gs mil in, Bearin after high lace the ma that it is y do wear out tomary to rep ce to ensure camshaft. The repairs, it is cus have to check the clearan er 13 of the Shop for d ble ssem you will ure in Chapt engine is disa new bearings, s this proced When fitting We will discus cified range. within the spe Shop Manual e 588 Manual. and Chapter 13, pag s that are 0.001 ize Bearing ble, bearings serious and Overs ished to be usa und to repair le in Undersize lightly and pol crankshaft has been gro erally availab haft is worn the gen nks If le. are cra a gs ilab en rin n ava Wh bea 0.050, ersize are ofte fitted. These may include 0.002 inch und ersize bearings can be tric undersized bearings of the bearings is und diameter ersize. Me journal wear, 30 inch und that the inside ings 0.020, and 0.0 mm. Undersize means Undersize bear ls. 10, rna 0.0 rsized ide jou t ove outs e to an and 0.750 have the sam dard the crankshaf n line bored h. 0.250, 0.500, diameter of block has bee diameter as stan bearand 0.040 inc the reduced the used when the in 0.010, 0.020, 0.030, smaller, to fit bearings, but 00 mm. These le rings may be er to 1.0 ilab bea thick ava and is ize n rial 50, ers Ov ing mate oversize rings are ofte 50, 0.500, 0.7 of crank0.2 bea ly use rsize ize e ical ers unde Th fit an diameter. Ov oversized bearings are typ n the standard bearing. ment has become shaft journal. tha tric lace ped Available me side diameter tically as component rep rings are stam e a larger out ma ons. Some bea t is currently in bearings hav decreased dra ings are chining operati bearings has g tha Oversize bear dard and undersize ive than many complex ma ck the size of the bearin on it. Some tion che thicker than stan ide rela fect to cor t-ef outs bearmore cos technician y with the size to increase the bearicate what size e of that allows the m the factor with a code technician ind typ diameter of the size stamped fro rings come that helps the rings are installed in this ing to fit an over inside use. New bea ping on them d bea The bearing bore. cks have a stam inally. If different size blo as e ine it. sam eng ove the diameter is the engine orig change this mark or rem ings. ing came on standard bear hnician should engine, the tec main ting rod and most connec Often erience that lubrication. been my exp d oil or lack of NOTE It has inated engine , the coolant-contaminate tam con AUTHOR’S by failure if it the oil pan s are caused cause of the the sludge in bearing failure determine the ; these days, that may ure is clear by to fail Try of . se ase the cau crankc engine of oil in the the life of the Be sure to discuss the oil, or the lack st bearings should last 0 km). Mo 02 to 321,87 ers. is premature. miles (241,4 h your custom 0 to 200,000 changes wit r filte reach 150,00 and of regular oil importance

Author’s Note This feature includes simple explanations, stories, or examples of complex topics. These are included to help students understand difficult concepts. PM 4/3/17 8:29

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xvi

110

Chapte

r5

Figure 5-8 cause the A pitted valve fac e allows valve to bu leakage tha rn. t wil

l eventually

Misadj tightly, it usted valves can also caus will be he e valve lea perform ld open an lo kage and strokes. ce through poor nger than it was burning. In designed If a valve se sive tem extreme cases, it aling of the co to. This is adjuste perature m ca can also d s. cause th bustion chambe n cause a reduct too e valves r during io to burn the appr n in if they ar opriate e expose d to exce s-

A Bit of History

A BIT O

FH

As recently ISTORY as early as as the mid-1980s , today’s en 60,000 or 75,00 it was not uncomm 0 mi gines can on for en gines to req run at lea les. Now due to adva st 150,000 uir miles befor nces in materials e valve recondition and ing e requiring valve servi machining, most of ce.

This feature gives the student a sense of the evolution of the automobile. This feature not only contains nice-to-know information, but also should spark some interest in the subject matter.

Head G

aske

58111_

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r_105-117

t Damag When a e head ga sket leaks context of , it can pr adjoinin combustion ch amber se esent a whole g cylinde host of aling , a rs. This significan different failu will tly sym also leak . This will caus lower the com re usually resu lts in a lea ptoms. In the pression e ou an to release t into the cool rough running and a lac d combustion k between two ing syste pressure of k m coolant leaking in and coolant. Th . This can caus of power. Combu both cylinders e the co e most co to the co stion ga ket failu oling sy ses can re m m stem pr mixing wi is the presence of bustion chambe mon symptom essure of r. th coolant in the oi Another common a blown head ga cap situations the oil, and it will look l. The oi sket , a compl sy m pt l fo om dipstick of white ete engin amy and of head is wi , sweet-s gasmelling e rebuild may be brownish, like a ll show signs of There exhaust to exit th required. This bu coffee milkshak coolant problem is a significant e. e rn In tailp differenc in s ex e in cost, ipe (Figure 5- g coolant causes these sible caus ist with combu 9). clouds sti lab es of low with a re perform on chamber seali or, and techni qu ance, in alistic es order to ng. It will be your e, depending timate. on what offer the customer job to recognize the posresponsib le repair options

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er underlayer;

the copp worn down to on the left are om end. The bearings from the bott Figure 5-17 engine knocking these created

SUMMARY

Review Questions Short-answer essays, fill-in-the-blanks, and multiplechoice questions follow each chapter. These questions are designed to accurately assess the student’s competence in the stated objectives at the beginning of the chapter.

s that the mance require t its support engine perfor nd and tha ■ Proper chanically sou igned. engine is me des as g nin functio perly sealed systems are er must be pro bustion chamb formance. ■ The com d engine per ket seal to provide goo and head gas gs, rin g, es, spark plu ■ The valv chamber. tion ability to bus its es com crib the gasoline des the greater ane rating of the number, ■ The oct ng; the higher resist knocki ng. cki to kno the resistance

winter be used in the ity fuel should l should be Higher volatil volatility fue HC emisstarts; lower d ive col ess ist exc ass t to mer to preven used in the sum lock. es or are three typ sions and vap and detonation se serious preignition, ■ Misfire, that can cau combustion of abnormal . s can engine damage ling or lubrication system defects. ine in the coo or serious eng abnor■ Failures al combustion lead to cause abnorm l eventually wil r wea engine formance. ■ Normal reduced per mal noises and

■

ESTIONS REVIEW QU er Essays

Short-Answ

Summary Each chapter concludes with summary statements that contain the important topics of the chapter. These are designed to help the reader review the contents.

lanks ket can cause _________ gas t the ______ mance. 1. A leak pas engine perfor mis compro ed ___, ___ ___ ___ _________ ___ 2. The ______ ___ _______________, and plug rk ____________ ition to the spa mber. add in ___ ____________ l seal the combustion cha wal and cylinder system and ____________ engine ns in the ___ 3. Malfunctio ______ system can cause the _________ problems. mechanical are tion bus com al es of abnorm ______, and 4. Three typ ___,_________ occurs when a n ____________ ___. Preignitio spark. ____________ _________ the ___ ___ ts star flame front hole in the top ly to burn a like is ___ ___ 5. _________ of the piston.

Fill-in-the-B er? bustion chamb

l the com ponents sea 1. What com roper ur from imp blems can occ 2. What pro sealing? er mb cha combustion on engine e ned valve hav ct will a bur 3. What effe ? performance describe? ng octane rati s a gasoline’s an 4. What doe en fuel with can occur wh ms ble pro d? 5. What volatility is use inappropriate ignition. 6. Define pre onation. . 7. Define det combustion of abnormal some causes lead to? 8. Describe can detonation ms ble pro ine 9. What eng ? engine noises ses abnormal 10. What cau

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xvii

SHOP MANUAL To stress the importance of safe work habits, the Shop Manual dedicates one full chapter to safety. Other important features of this manual include:

CHA PTE R 10

VALVETRAIN SERVIC E

Performance-Based Objectives These objectives define the contents of the chapter and what the student should have learned upon completion of the chapter.

Terms to Know List Terms in this list are also defined in the Glossary at the end of the manual.

Special Tools Lists Whenever a special tool is required to complete a task, it is listed in the margin next to the procedure.

review of this chapter, you should understand and be able to describ How to inspect the camsh e: aft for ■ How to recond straightness. Basic Tools ition rocker arms and replace studs. How to measure the camsh Basic mechanic’s aft lobes ■ How to evaluate and measu and journals and determ tool set re valve ine needed springs. repairs. Service manual ■ How to adjust ■ How to inspec the valvetrain during t solid and hydraulic installation of hydraulic lifters and determine neede lifters. d repairs. ■ ■ How to perfor How to adjust valve cleara m the leak-down test nces on on engines using mechanical hydraulic lifters and accura lifters. tely interpret the results. ■ How to prope rly reassemble the ■ How to inspec cylind er head. t the pushrods and determine needed repairs ■ How to install a cylinder head. . ■ How to descri ■ How to replac be the methods used e valve seals with the to correct rocker arm geom cylinder head installed etry. on the engine. 7 er Chapt that Terms To Know that there are no DTCs and harging system, be sure

The most important terms to know are highlighted and defined in the margin. Common trade jargon also appears in the margins and gives some of the common terms used for components. This feature helps students understand and speak the language of the trade, especially when conversing with an experienced technician.

Each chapter begins with a list of the basic tools needed to perform the tasks included in the chapter.

■

322

intake air temperaOn a PCM-controlled turboc properly. A fault in the n systems are functioning re. Repair all related Lobe lift the fuel and ignitio PCM to limitreboost pressu example, could cause the Seat pressu Nose ture sensor, for . harger Spring mning the turboc free length malfunctions before conde

Base circle Camshaft Duration Heel Leak-down Lifter

Open pressure

Overlap er Removal Turbocharg Pushro

Spring shims

Spring squareness engine; for example, varies depending on the engine be erdsremoval procedure The turbocharg facturer recommends the Rocker arm Nissan 300 ZX, the manu a as such the turbocharger may , cars, ations some on other applic to the turbocharger. On removal proceremoved to gain access s follow the turbocharger Alway e. vehicl the in l turbocharger removed with the engine INTRODUCTIO be N The following is a typica facturer’s service manual. dure in the vehicle manu The valvetrain works to al procedure: remov open and close the valves cooling system. at the propeand run, the components of drain r time. Asthe the engine is batter y cable, the valvet negati rainthe wear nnect andvestretch 1. Disco . altered. , causin the valve harger openin pipe from thegturboc gand to the be engine block. Disconnect the exhaust This chapter discus2.ses t between the turbocharger the bracke metho rt suppo ds used the ve to inspect and repair housin 3. Remo semble the cylinder head, g on the turbocharger. adjust thevalves the oil drain back the valvetrain, reasremove bolts from , diagno se a failed thead at the block outlet, and worn valve stem seals on4. Removethe nut tube gasket inlet , and coolan the car.nnect replac harger e turboc theber, before deciding to rebuild compo as camshafts and lifters,5. Disco Remem nents such the cost of rebuil t. t bracke components. ding uppor compo related and t, nents must of replacing them. These the tube-s bracke be compa r box,red to the cost nt, air cleane components air usuall m eleme cleaneyrbe purchased cal connector, and vacuu rebuilding; however, there 6. Remove thecan electri new at bodyexpen le less se than linkage, thrott may be instan cesaccele the whenrator rebuilding is a viable option 7. Disconnect . e the three hoses. hose clamps, and remov inlet harger urboc y-to-t 8. Loosen the throttle-bod s. Remove the throttle body. manifold attaching screw throttle-body-to-intake on the compressor wheel harger discharge hose clamp 9. Loosen the lower turboc screw. Remove housing. and the fuel line bracket 441 screws anifold take-m pull the fuel rail and injec10. Remove the fuel-rail-to-in shield-retaining clips, and of wire. piece a two fuel-rail-bracket-to-heatwith the n 58128_ch10_hr_441-494.indd positio this 441 Tie the fuel rail in g. tors upward out of the way. housin line from the turbocharger 11. Disconnect the oil supply heat shield. 4/4/17 8:43 PM old 12. Remove the intake manif harger and the water box. return line from the turboc line. Disconnect the coolant 13. er head and remove the 256 Chapter 13 bracket from the cylind old, and manif st exhau Remove the line-support the to retaining the turbocharger Special Tools down14. Remove the four nuts Move the turbocharger from the manifold studs. unit up and out of Pressure gauge remove the turbocharger vehicle, and then lift the ger side of the Parting face Hand pressure pump ward toward the passen t. Dial indicator the engine compartmen

ers after a turbocharger returning vehicles to custom e with them. Remind CUSTOMER CARE When maintenanc discuss proper care and shutting the vehicle replacement, be sure to before down wind to the turbo them that they should allow idle for a minute after drivthey should let the engine them that regular oil off. This simply means that You should also remind off. n ignitio the customer g Figureing turnin 13-10 before A multip can help ensure that the lepiece thrust bearinare turbocharger life. They changes g. essential to Bearing for turbocharger service. won’t be back anytime soon

crown Figure 13-11 Bearin g crown maintains close and bottom of the bearin clearances at the top g, where most of the loads are applied.

Shop Manual Chapter 13, page 588

Margin Note

Basic Tools Lists

Upon completion and

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58128_ch07_hr_299-340.indd

Undersize bearings have the same outsid e diameter as standard bearings, but the bearing material is thicke r to fit an undersize crankshaft journal. Oversize bearings are thicker than standard to increase the outsid e diameter of the bearing to fit an oversize bearing bore. The inside diameter is the same as standard bearings.

322

oil bearingcharg ponent Inspection s er sCom Turbo clearance fall within the rang s turbocharger disassembly, inspect the wheel (0.0508 mm). Thes e of 0.0008 inch (0.02 er recommend with confactur are just lubric 03 or typic mm) If the vehicle emanu al clearance to ation Lack of lubricant 0.002 inch gs. for the s; alwaed. remov engine you ys chec housings are k the ending thework the end housin ons spec ufact rub urer’ wheel and shaft afterare on. g failure, which leads to man ificat ions Bear ings areoil s in .bearin a wear resultitem taminated They are designed camshaft. to wear and prote They do wear out after ct the crankshaft high mileage and expo engine is disassemb or sure to contaminated led for repairs, it is oil. When the customary to repla When fitting new ce the main, rod, and bearings, you will cam bearings. have to check the within the specified clearance to ensure range. We will discu that it is Manual. ss this procedure in Chapter 13 of the Shop

4/4/17 6:18 PM

Undersize and Ove

rsize Bearings

When a cranksha ft is worn lightly and polished to be usab 0.002 inch undersize le, bearings that are are often available. 0.001 and If the crankshaft has journal wear, unde been ground to repa rsize bearings can ir serious be fitted. These bear 0.010, 0.020, and ings are generally 0.030 inch undersize available in . Metric undersize 0.250, 0.500, and 0.750 d bearings mm. Undersize mean smaller, to fit the redu s that the inside diam may include 0.050, ced diameter of the eter of the bear ings is crankshaft journals. Oversize bearings may be used when diameter. Oversize the block has been bearings are often line bored to an over available in 0.010 Available metric over sized , 0.020 sized bearings are , 0.030, and 0.040 typically 0.250, 0.500 bearings have a large inch. , 0.750, and 1.000 mm. r outside diameter than the standard These and undersize bear bearing. The use ings has decreased of dram over more cost-effective atically as compone size than nt replacement has become with a code that allow many complex machining operation s. Some bearings are s the technician to stamped check the size of the use. New bearings come stamped from bearing that is curre the factory with the ntly in engine blocks have size correlation on a stam it. Some ing came on the engin ping on them that helps the technicia n indicate what size e originally. If diffe engine, the technicia rent sized bearings bearare installed in this n should change this type of mark or remove it. AUTHOR’S NOT E It has been my experience that most bearing failures are connecting rod and caused by contamin main ated engine oil or the cause of failure lack of lubrication. is clear by the sludg Often e in the oil pan, the oil, or the lack of oil coolant-contaminate in the crankcase. Try d is premature. Mos to determine the caus t bear e of the failure if it reach 150,000 to 200,0 ings should last the life of the engin e; these days, that 00 miles (241,402 may to importance of regu lar oil and filter chan 321,870 km). Be sure to discuss the ges with your custo mers.

Author’s Note This feature includes simple explanations, stories, or examples of complex topics. These are included to help students understand difficult concepts.

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xviii

Photo Sequences Many procedures are illustrated in detailed Photo Sequences. These photographs show the students what to expect when they perform particular procedures. They also familiarize students with a system or type of equipment that the school might not have.

14

Chapter 1

PHOTO SEQUENCE

2

Typical Procedure for

Lifting a Vehicle on a

P2-1 Drive the vehicle onto the sure your wheels are centered hoist. Make , and drive slow. If needed, stick your head out of the window or have an assistant help guide you. Never stand in front of a moving vehicle.

P2-4 Make sure that the locks are set and the hoist is level. Always rest the hoist on the locks. Most drive-on lifts are hydrauli cally lifted, but their locks are air operated .

Drive-On Hoist

P2-2 Place a wheel chock behind the other end of the vehicle to ensure it doesn’t roll when being lifted.

P2-5 Position the rolling jacks on a suitable location. Check the service manual for correct locations.

P2-3 Raise the vehicle to a comfortable height.

P2-6 Once the axle is to a height you want it, lower it and rest it on the locks. tems Most151 rolling ting Sys jacks Op are air eraoperated and have manual locks.

vicing Engine

and Ser Diagnosing

NTINUED)

UENCE 5 (CO

PHOTO SEQ

References to the Classroom Manual t the P5-10 Reconnec

duce a highstarter will pro Figure 1-12the Typical jack stands.small, the starter rs is excessive, too the two gea rned clearance is ce between n switch is retu cranked. If the itio ng ign bei is If the clearan the ine starts and while the eng r the engine pitched whine ed whine afte itch h-p hig will make a position. to the RUN a is too small 58128_ch01_hr_001-038.indd sing breakage have a little 14 se of drive hou ter to The major cau g gears. It is always bet SERVICE TIP ion and rin pin the n wee ce. clearance bet than too small a clearan ce more clearan Figure 1-11 Typical hydrauli c floor jack.

Service Tips Whenever a shortcut or special procedure is appropriate, it is described in the text. Generally, these tips describe common procedures used by experienced technicians.

LUBRICAT

References to the appropriate page in the Classroom Manual appear whenever necessary. Although the chapters of the two manuals are synchronized, material covered in other chapters of the Classroom Manual may be fundamental to the topic discussed in the Shop Manual.

starter operates that the new king P5-11 Verify noise by cran without excess properly and a few times. the engine over

battery.

ual Classroom Man e 60 Chapter 4, pag

1/30/17 4:18 PM

D SERVICE TESTING AN ION SYSTEM

used to clearances Bearings are ent upon oil s created re is depend es excesTesting carr y the load ring becom life. Oil pressu forces. g ial to engine l and the bea by rotational ult of bearin ssure is essent rance between a journa r, are the res eve r. how wea Proper oil pre , clea p ons the deliver y. If ssure conditi de, and oil pum perapre gra oil oil er low and proper improp . Not all essive tem er oil level, result of exc pressure is lost sive, 632 lude improp ning oil as a Chapt causeserinc 13 low oil pressure is thin wear. Other el will Too low a lev due mon cause of the oil level. Another com tion. ng cki che h, it may be dilu ted, begin by level is too hig tures or gas n misfire, e. If the oil ssure is suspec l pump, ignitio y, check 5 fue If low oil pre to aerate and lose volum d age pump result of a dam condition are satisfactor 3 nkcase as a cause the oil 1 testing is oil level and ering the cra Oil pressure the to gasoline ent or engine flooding. If the 4 rmin 6 dete 2 e8 unit from the used to r, 7 ding bearre sen leaking injecto ssure gauge. pre condition of the re gauge to oil the oil pressu an nal using t the oil pressu test, remove and other inter nec re the ings oil pressure ssu con tch rs, pre an oil ine idles. Wa t size adapte ne components. eng rec engi cor the To perform as the the ge ng Increase Pulley erve the gau e 4-20). Usi temperature. engine (Figur Start the engine, and obs drops due to h the manuive wit ess e. ults exc sag res h the the oil pas are the test s to note any gauge. Comp cifications wit engine warm After gauge as the observing the provide oil pressure spe y warmed up. rs to 2,000 while engine rpm Manufacture be sure the engine is full confirm cifications. engine, and re; the rt sta t, facturers’ spe l operating temperatu Water sending uni re ma ssu nor pre at oil engine ll the pump plete, reinsta Intake the test is com

Oil Pressure

Bolt

manifold

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Timing cover

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58128_ch04_h

Front cover gasket

Cylinder block

Figure 13-77 Water pump, pulley, and timing

Caution

Warnings and Cautions

Do not install the damper by striking it with a hammer. The damper or crankshaft may be damaged.

Cautions appear throughout the text to alert readers to potentially hazardous materials or unsafe conditions. Warnings advise the student of things that can go wrong if instructions are not followed or if an incorrect part or tool is used. 58128_ch13_hr_587-658.indd

cover installation.

Figure 13-78 Intake manifold and typical torque

sequence.

(Figure 13-79). Most gasket s are marked to indicate proper direction for install After testing the fit, remov ation. e the intake gasket. Apply sealer at any locations direct the service manual. On V-type engines, the four ed in intersection points of the and the engine block usuall cylinder heads y require sealer. On V-typ e engines, locate the front end seals onto the block and rear . In addition, the intake manifold gasket may have tabs that must fit into the alignment head gasket for proper installation (Figure 13-80 The studs will hold the gasket ). in place while the manif engines. On V-type engine old is installed on most in-line s, the gasket may slip as the manifold is lowered prevent this, use an adhes into place. To ive to hold the gasket in place. Carefully lower the position. Then install the manifold into fasteners and torque to specifications. WARNING If the cylind er heads on a V-type engin intake manifold must be e have been machined, machined accordingly the so. Failure to machine manifold before reasse the intake mbly may cause oil and coolant leaks or consu well as reduced performan mption as ce. Refer to Chapter 9 for more information. On fuel-injected engines, install the fuel rail and the intake plenum and gasket the fasteners to the specif ied value. Next, install the . Torque throttle body assembly (Figur Make sure to replace e 13-81). the high-pressure (2,000 psi) fuel lines when instal camshaft-driven high-p ressure pump onto the ling the cylinder head of GDI (gasol injection) systems. ine direct Next, install the exhaust manifold and gasket. Replac with the exhaust manifold. e all mounting hardware The old fasteners may have used been weakened as a result of the

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

xix

Case Studies

570

Chapter 12

CASE STUDY

damr was excessively scuffed and block indicated that one cylinde customer. Inspection of a V8 engine and discussed them with the hed the options available to bore each cylinder having and e aged. The technician researc feasibl not of a new block was most It was decided that the cost e, it was decided that the ting of new pistons. In this instanc tion of a sleeve. After comple would require the purchase g the block was the installa to turn cost-effective method of repairin ons on the engine block, the technician was ready operati maining the of machin one all the required notes taken indicated that tion inspec s The haft. journal her attention to the cranks finish. All other main-bearing ian grinding to restore its surface fail in this manner, the technic bearing journals required l to have only one bearing l bearing was undersize origina the were good. Realizing it is unusua that red discove noise very closely and inspected the old bearing attempted to remove an engine not ground. Someone had the journal even though the journal was ce. The extra friction caused bearing to take up clearan all main-bearing journals were by simply installing a thicker haft position in the block, cranks were ces proper in clearan oil mainta to score. To were installed, and rd undersize, new bearings reputation ground to the next standa interest of the customer, your to find what is in the best checked. By taking the time grow. as an honest technician will

Each chapter ends with a Case Study describing a particular vehicle problem and the logical steps a technician might use to solve the problem. These studies focus on system diagnosis skills and help student gain familiarity with the process.

ASE-Style Review Questions

QUESTIONS ASE-STYLE REVIEW

the pistons should come 4. Technician A says that e the tightening out the top of the block. 1. Technician A says to revers cylinder head. the ing on the edge of the loosen drive to sequence when Technician B says to remove the pistons. the main caps starting piston skirt with a punch Technician B says to loosen and moving toward the t? correc at the front of the engine is Who C. Both A and B rear. A. A only D. Neither A nor B Who is correct? B. B only C. Both A and B only A. A removed for inspection. 5. The crankshaft has been D. Neither A nor B B. B only d the fillet is a aroun area the Technician A says cracks. you can pry most common location for stress 2. Technician A says that the number 1 with two big pry bars. ician B says a crack near harmonic balancers off Techn l may indicate a can damage the piston connecting-rod journa Technician B says that you protect the threads while faulty vibration damper. crankshaft if you do not using a puller. Who is correct? C. Both A and B Who is correct? A. A only C. Both A and B D. Neither A nor B A. A only B. B only Neither A nor B D. B. B only ready for inspection. 6. The cylinder block is warpage can be checked the engine to Technician A says that deck 3. Technician A says to rotate ing the timing and feeler gauge. using a precision straightedge TDC number 1 before remov bearing saddle ician B says that the main mechanism. Techn l or written ed with a precision menta a check be make to can ent says B alignm Technician . . marks gauge timing feeler a the of and n Name straightedge of the note ____locatio ________ ________ Who is correct? ________ Who is correct? ____B____ PERFORM C. Both A and B C. Both A and __ only A. ADa A. A only ING AN B te ______ er A nor B nor A OIL Neith Upon comp D. AN ________ D. Neith DerFILTER B. B only only letion of B B. ____ change. this job sh CH AN G eet, you sh E ould be ab JO B SH EE NATEF Co le to prope T rrelation rly perform an oil and This job filter sheet addre sses the fol lowing AS D.10. T/ MAST tas Perform engine oil k for Engin This job and filter e Repair: sheet addre change. sses the fol lowing M D.5. LR task for 570 Pe 3-586.indd rfo 12_hr_53 58128_ch rm engin Engine Re e oil and pa ir: Tools an filter chan d Materia ge. ls • Technic ian’s tool set • Shop rag • Correct type of en gine oil • Service manual • Oil filt er wrench • Used oil container • Torqu e wrench Describe the vehic le being worked on Year ____ ________ 189 : Systems ________ ing Engine Operating _ Make __ VIN ____ Diagnosing and Servic ________ ________ ________ ________ ___ Mod ________ Procedur el _ __ En ________ gine type e ________ and size __ ___ ________ Follow the NS ________ insLLEN tructionsGE QUESTIO ________ ASE CHA below to __ heater core may be complete 1. Pull the Technician B says that the es the engag it oil oil fill lev and filter ng noise when grindi a el g. r makes ch ind leakin an 1. A__starte ica ge tor (dipstic . Task Comp ________ k), __ teeth. leted an eel __ t? flywh d __ correc the ________ ednote the level andWho is __ ____ shimm ______ician co ition C. Both A and B ________ says that it could__be A __ ______ Techn A only of the oil. ________ A. nd ________ ______ ________ A nor B er Neith perly. __ D. impro __ __ __ __ ________ ________ ____gear could B only ______ __ says _____ starter drive ________ B. ____that ____the ician B__ ng ________ ________ 2. WTechn that his oil pressure warni ______ ________ hat are the says er__ 4. A custom ged. _______ ________ be dama oil AP An . I idling an is ma car d __ nual for the SAE rat ______light s on while the come ______ cot? rrect infor ings for the oil yo ________ Who is correc ____ _____low oil pressure. matio uBare going test shows ________ re and A pressu n)? Both C. to use (co may be A. A only ______________ nsult that the engine bearings says theAser ician __D. Techn ____ ________ er A nor B Neith vice ______ ________ ________ B. B only ________ ________ worn. ________ ________ 3. Warm t draw ____curren the oil pressure relief valve ______ that the engin starter says a B __ ming ician __ perfor __ Techn __ is ___ ________ e to opera technician plu2.g A is rem ________ be stuck closed tingwill . turn over. The test ovedse temnot perat ________ . the engine may ure. Ththe test becau _______ e starter 4. Properl flow faster Who is correct? te that the current draw on oil willthe: y raiseindica results when the the vehicl ication. This means that drain C. Both A and B on a lift 5. Place is higher than theespecif . A. A only h the used oilrco D. Neither A nor B plug, anA. nta id is bad. soleno d letstarte B. B only the oil flo iner (or catch basin container w intcharg ) un ing. o de move from be the r needs y cause the the h gauge does not engine. B. batter t temperature flow rate container. You ma drain plug. Re5.mo coolan A and posit y ve the drain the vehicle is driven. n switch is bad. ion will ch have to adjust the its lowest reading when 6. Now remC. ignitio an posit h . ge as more ion of the rature locked tempe lly t statica ove engin coolan the hydro oil may be flows A says that panels. MD. the oile filt Techn out ician of the ake sure all er. You may ha nected. of the oil pressuve to uswith pressure sensor wires may be discon e a spaec ws intrized ial wrench ostat could be 3. A cooling system isflo therm o theminut the that the says B es, us or ed oil conta removTechn 15 e someician iner. tester to locate a leak. After stuck open. from 15 psi to 5 psi, h tester gauge has dropped leaks in the engine Who is correct? and there are no visible C. Both A and B A. A only compartment. engine may have an D. Neither A nor B 197 Technician A says that the B. B only leak. t gaske 197 internal head

Each chapter contains ASE-Style Review Questions that reflect the performance objectives listed at the beginning of the chapter. These questions can be used to review the chapter as well as to prepare for the ASE certification exam.

Job Sheets

20

ASE Challenge Questions Each technical chapter ends with five ASE challenge questions. These are not more review questions; rather, they test the students’ ability to apply general knowledge to the contents of the chapter. 58128_ch0

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Located at the end of each chapter, the Job Sheets provide a format for students to perform procedures covered in the chapter. A reference to the NATEF Tasks addressed by the procedure is included on the Job Sheet.

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

xx

SUPPLEMENTS Instructor Resources The Today’s TechnicianTM series offers a robust set of instructor resources, available online at Cengage’s Instructor Resource Center and on DVD. The following tools have been provided to meet any instructor’s classroom preparation needs: ■■ An Instructor’s Guide including lecture outlines, teaching tips, and complete answers to end-of-chapter questions. ■■ PowerPoint presentations with images and animations that coincide with each ­chapter’s content coverage. ■■ Cengage Learning Testing Powered by Cognero® provides hundreds of test questions in a flexible, online system. You can choose to author, edit, and manage test bank content from multiple Cengage Learning solutions and deliver tests from your LMS, or you can simply download editable Word documents from the DVD or Instructor Resource Center. ■■ An Image Gallery includes photos and illustrations from the text. ■■ The Job Sheets from the Shop Manual are provided in Word format. ■■ End-of-chapter Review Questions are provided in Word format, with a separate set of text rejoinders available for instructors’ reference. ■■ To complete this powerful suite of planning tools, correlation guides are provided to the NATEF tasks and to the previous edition.

REVIEWERS The author and publisher would like to extend special thanks to the following instructors for reviewing this material: Matthew Bockenfeld Vatterott College—Joplin Joplin, MO David Chavez Austin Community College Austin, TX Joseph Cortez Reynolds Community College Richmond, VA Jason S Grice Black Hawk College Galva, IL

Todd Mikonis Manchester Community College ­Manchester, NH Vincenzo Rigaglia Bronx Community College Bronx, NY Ronald Strzalkowski Baker College of Flint Flint, MI Michael White The University of Northwestern Ohio Lima, OH

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 1

SAFETY AND SHOP PRACTICES

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■

■■ ■■ ■■ ■■ ■■ ■■ ■■

The importance of safety and accident prevention in an automotive shop. The basic principles of personal safety, including protective eyewear, clothing, gloves, shoes, securing hair and jewelry, and hearing protection. The proper lifting procedures and precautions. The procedures and precautions for safely using tools and equipment. Safety precautions regarding the use of power tools. Proper safety precautions during the use of compressed air equipment. Proper vehicle lift operating and safety procedures. All safety precautions when hydraulic tools are used in the automotive shop. The recommended procedure while operating hydraulic tools such as presses, floor jacks, and vehicle lifts to perform automotive service tasks.

■■

■■ ■■ ■■

■■ ■■

■■ ■■

■■

The safety precautions while using cleaning equipment in the automotive shop. All shop rules when working in the shop. How to operate vehicles in the shop according to shop driving rules. What should be done to maintain a safe work area, including handling vehicles in the shop and venting carbon monoxide gases. The various government regulations and safety laws. How a chemical manufacturer provides safety warnings through. Safety Data Sheets (SDS). The location of marked safety areas and the posted evacuation routes. The location and the types of fire extinguishers and knowledge of the procedures for using fire extinguishers. Awareness of the safety aspects of hybrid vehicle high-voltage circuits.

Basic Tools Basic mechanic’s tools set Service information

Terms To Know Abrasive cleaning Carbon monoxide (CO) Chemical cleaning Environmental Protection Agency (EPA) Floor jack Hydraulic press Jack stands Lockout tag

Occupational Safety and Health Administration (OSHA) Particulates Pneumatic tools Power tools Right-to-Know laws Safety Data Sheets (SDS) Safety glasses

Sulfuric acid Thermal cleaning Workplace Hazardous Materials Information Systems (WHMIS) Z-87.1

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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INTRODUCTION Safety and accident prevention must be a top priority in all automotive shops. There is great potential for serious accidents simply because of the nature of the business and the equipment used. In fact, the automotive repair industry is rated as one of the most dangerous occupations in the country. Vehicles, equipment, and many parts are very heavy, and parts often fit tightly together. Many components become hot during operation, and high-fluid pressures can build up inside the cooling system, fuel system, or battery. Batteries contain highly corrosive and potentially explosive acids. Fuels and cleaning solvents are flammable. Exhaust fumes are poisonous. During some repairs, technicians can be exposed to harmful dust particles and vapors. High voltage on some types of vehicles present shock and burn hazards. Good safety practices reduce the risk of harm from these potential dangers. A careless attitude and poor work habits invite disaster. Shop accidents can cause serious injury, temporary or permanent disability, and death. Safety is not an accident and is not an individual effort. It takes everyone working together to notice and report any hazards to the employer. Both the employer and the employees must work together to protect the health and welfare of all who work in the shop. This chapter contains many safety guidelines concerning personal safety, tools and equipment, and work area, as well as some of the responsibilities you have as an employee and responsibilities your employer has to you. In addition to these rules, special warnings have been used throughout this book to alert you to situations where carelessness could result in personal injury. Finally, when working on cars, always follow safety guidelines given in the service information and other technical literature. They are there for your protection.

PERSONAL SAFETY Personal safety simply involves those precautions you take to protect yourself from injury. These include wearing protective gear, dressing for safety, and correctly handling tools and equipment.

Eye Protection

Safety glasses have lenses that resist breaking and protect the eyes from airborne objects or liquids. If you wear prescription glasses, wear safety goggles that will securely fit over your glasses.

Your eyes can become infected or permanently damaged by many things in a shop. Some repair procedures, such as grinding, result in tiny particles of metal and dust that are thrown off at very high speeds. These metal and dirt particles can easily get into your eyes, causing scratches or cuts on your eyeball. They can also get into your lungs if you are not properly protected. Pressurized gases and liquids escaping a ruptured hose or fuel line fitting can spray a great distance. If these chemicals get into your eye, they can cause blindness. Dirt and sharp bits of corroded metal can easily fall down into your eyes while you are working under a vehicle. Eye protection should be worn whenever you are exposed to these risks. To be safe, you should wear safety glasses whenever you are working in the shop. There are many types of eye protection available (Figure 1-1). To provide adequate eye protection, safety glasses have lenses made of safety glass. They also offer side protection. Regular prescription glasses do not offer sufficient protection and therefore should not be worn as a substitute for safety glasses. You should wear safety glasses at all times. To help develop this habit, wear safety glasses that fit well and feel comfortable. Most safety glasses that provide good protection are rated by the American National Standards Institute (ANSI). The ANSI has established a standard for producing a lens that is durable and safe for most situations. This standard

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

B

A

C

Figure 1-1  (A) Safety goggles, (B) face shield, and (C) safety glasses.

is the Z-87.1 standard, and most safety glasses that are ANSI approved have a simple Z-87.1 stamping on them. If chemicals such as battery acid, fuel, or solvents get into your eyes, flush them ­continuously in an eyewash station (Figure 1-2) or with sterile water from an eye wash bottle.

Z-87.1 is the ANSIestablished standard for safety glasses.

Figure 1-2  Eyewash station. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Have someone call a doctor and get medical help immediately. Be familiar with the location of all safety equipment when you enter a new shop.

Clothing Caustic chemicals can burn through cloth and skin.

Your clothing should be well-fitted and comfortable but made with strong material. Loose, baggy clothing easily can get caught in moving parts and machinery. Some technicians prefer to wear coveralls or shop coats to protect their personal clothing. Cut-offs and short pants are not appropriate for shop work. Many shops will provide you with uniforms. Automotive work involves the handling of many heavy objects that can be accidentally dropped on your feet or toes. Always wear shoes made of leather or a similar material, or boots with nonslip soles. Steel-tipped safety shoes can give added protection for your feet. Sports sneakers, street shoes, and sandals are not appropriate in the shop. Good hand protection is often overlooked. A scrape, cut, or burn can limit your effectiveness at work for many days. A well-fitted pair of heavy work gloves should be worn during operations such as grinding and welding or when handling high-temperature components. Always wear approved rubber gloves when handling caustic chemicals. Caustic chemicals are strong and dangerous chemicals. They can easily burn your skin. Be very careful when handling this type of chemical. Many technicians now choose to wear close-fitting surgical gloves that offer some protection from toxic chemicals such as engine oil, gasoline, brake fluid, and cleaning chemicals (Figure 1-3). It is important to remember that your skin is an organ and it will absorb some of the fluids that are placed on it. Close-fitting surgical gloves are very inexpensive, disposable, and come in different versions, such as latex, powdered, and nitrile. These gloves also save you the time of scrubbing filthy hands every time you want to get into the vehicle or take a road test. One bit of grease in a customer’s vehicle can destroy your reputation with the customer, no matter how excellent the rest of your work is. These disposable and inexpensive gloves are available in drugstores, retail stores, and auto parts stores, as well as from the major tool manufacturers.

Figure 1-3  These tight-fitting latex gloves keep your skin safe from dangerous fluids.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Many mechanics also choose to wear thicker, padded gloves. These gloves are a little bit thicker than the surgical gloves, but offer better protection to sharp or hot objects. Most of the higher-quality gloves of this type offer padded protection in high-wear areas, such as the palm and fingers. They are also very comfortable when you have to work on a very hot engine component and you cannot wait for it to cool down. It is a good practice to have many different types of gloves in your toolbox so you can switch to the one that fits the job.

Ear Protection Exposure to very loud noise levels for extended periods of time can lead to a loss of hearing. Air wrenches, engines running under a load, and vehicles running in enclosed areas can all generate annoying and harmful levels of noise. Simple ear plugs or earphone-type protectors should be worn in constantly noisy environments.

Hair and Jewelry Long hair and loose, hanging jewelry can create the same type of hazard as loose-fitting clothing. They can become caught in moving engine parts and machinery. If you have long hair, tie it back or cover it with a cap. Never wear rings, watches, bracelets, or neck chains. These easily can get caught in moving parts and cause serious injury.

Other Personal Safety Warnings ■■

■■

■■ ■■

■■

Never smoke while working on a vehicle or while working with any machine in the shop. It is good practice to never smoke in the shop, because of the flammable chemicals and fluids that could be nearby. Playing around or horseplay is not appropriate for professional technicians. Such things as air nozzle fights, creeper races, or practical jokes can hurt people and have no place in the professional workplace. To prevent serious burns, keep your skin away from hot metal parts such as the radiator, exhaust manifold, tailpipe, catalytic converter, and muffler. When working with a hydraulic press, make sure that the pressure is applied in a safe manner. It is generally wise to stand to the side when operating the press. Always wear safety glasses. Properly store all parts and tools by putting them away in a place where people will not trip over them. This practice not only cuts down on injuries, but also reduces time wasted looking for a misplaced part or tool.

AUTHOR’S NOTE  In my experiences as an automotive technician, I can consider myself lucky. I have come to realize that compared to other technicians I have not been severely injured or harmed while on the job. I have known many technicians who did not wear the appropriate safety items and have been injured as a result; these injuries could have been prevented. Some of these technicians can no longer perform their job, and as a result they have been forced to assume a different job at their place of employment or completely change careers. Your success as an automotive technician will depend on you being able to use your hands, eyes, back, and every other part of your body. Be sure to take good care of your body.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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LIFTING AND CARRYING Knowing the proper way to lift heavy objects is important. You should also use back ­protection devices when you are lifting a heavy object. Always lift and work within your ability, and ask others to help when you are not sure that you can handle the size or weight of an object. Even small, compact parts can be surprisingly heavy or unbalanced. Think about how you are going to lift something before you begin. When lifting any object, ­follow these steps: 1. If the object is to be carried, be sure your path is free from loose parts or tools. 2. Place your feet close to the object. Position your feet so you will be able to maintain a good balance. 3. Keep your back and elbows as straight as possible. Bend your knees until your hands reach the best place to get a strong grip on the object (Figure 1-4). 4. If the part is in a cardboard box, make sure the box is in good condition. Old, damp, or poorly sealed boxes will tear and the part will fall out. 5. Firmly grasp the object or container. Never try to change your grip as you move the load. 6. Keep the object close to your body, and lift it up by straightening your legs. Use your leg muscles, not your back muscles. 7. If you must change your direction of travel, never twist your body. Turn your whole body, including your feet. 8. When placing the object on a shelf or counter, do not bend forward. Place the edge of the load on the shelf, and slide it forward. Be careful not to pinch your fingers. 9. When setting down a load, bend your knees and keep your back straight. Never bend forward—this strains the back muscles. 10. Set the object onto blocks of wood to protect your fingers when lowering something heavy onto the floor. 11. If the object is too heavy to lift, try using a wheel dolly to move it (Figure 1-5).

HAND TOOL SAFETY Many shop accidents are caused by improper use and care of hand tools. These hand-tool safety steps must be followed: 1. Keep tools clean and in good condition. Worn tools may slip and result in hand injury. If a hammer is used with a loose head, the head may fly off and cause

Position body over load Keep back as erect as possible

Straight back

Weight close to body

Use leg muscles Legs bent

Figure 1-4  Use your leg muscles, never your back, to lift heavy objects. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Figure 1-5  Use a two-wheel dolly if the load is very heavy.

personal injury or vehicle damage. Keep all hand tools clean; greasy tools can slip and cause cuts and bruises. If a tool slips and falls into a moving part, it can fly out and cause serious injury to you or the vehicle. Keeping your tools neat and organized can save you time while you work. If you spend 10 minutes looking for a ­particular socket that you didn’t put back in its proper spot, that could be 10 ­minutes less that you are paid for. Or worse, you could leave it in the vehicle you were working on and lose it forever. 2. Use the proper tool for the job. Make sure the tool is of professional quality. Using poorly made tools or the wrong tools can damage parts or the tool itself, or cause injury. Do not use broken or damaged tools. 3. Be careful when using sharp or pointed tools. Do not place sharp tools or other sharp objects in your pockets. They can stab or cut your skin, ruin automotive upholstery, or scratch a painted surface. 4. Tool tips that are intended to be sharp should be kept in a sharp condition. Sharp tools, such as chisels, will do the job faster with less effort. Dull tools can be more dangerous than sharp tools.

POWER TOOL SAFETY Power tools are operated by an outside source of power, such as electricity, compressed air, or hydraulic pressure. Safety around power tools is very important. Serious injury can result from carelessness. Always wear safety glasses when using power tools. If the tool is electrically powered, make sure it is properly grounded. Check the wiring for cracks in the insulation and bare wires before using it. Also, when using electrical power tools, never stand on a wet or damp floor. Disconnect the power source before performing any service on the machine or tool. Before plugging in any electric tool, make sure the switch is off to prevent serious injury. When you are through using the tool, turn it off and unplug it. Never leave a running power tool unattended.

Power tools are ­operated by an outside power source. This may include batteries, ­electrical outlets, ­compressed air, or hydraulic fluid.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Lockout tag is used to prevent accidental ­operation of tools or equipment needing repair or service.

When using power equipment on a small part, never hold the part in your hand. Always mount the part in a bench vise or use vise grip pliers. Never try to use a machine or tool beyond its stated capacity or for operations requiring more than the rated power of the tool. When working with larger power tools, such as bench or floor equipment, check the machines for signs of damage before using them. Any equipment that needs service or maintenance should be taken out of service (tagged out) using a lockout tag to prevent anyone from using it (Figure 1-6). Place all safety guards into position (Figure 1-7). A safety guard is a protective cover over a moving part. It is designed to prevent injury. Wear safety glasses or a face shield. Make sure there are no people or parts around the machine before starting it up. Keep your hands and clothing away from the moving parts. Maintain a ­balanced stance while using the machine.

DA N

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D OP O NO ER T AT E

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ED CK T O U L O

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em tr

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T on his l ly b ock me e r /ta : em g m De pt. ove ay : db Ex pe y: cte Na

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Figure 1-6  Lockout tag.

Figure 1-7  Safety guards on a bench grinder.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Hydraulic Press WARNING  When operating a hydraulic press, always be sure that the components being pressed are supported properly on the press bed with steel supports. When hydraulic pressure is supplied to improperly supported components, they may drop off the press, resulting in leg or foot injuries. WARNING  When using a hydraulic press, never operate the pump handle when the pressure gauge exceeds the maximum pressure rating of the press. If this pressure is exceeded, some part of the press may suddenly break and cause severe personal injury.

When two components have a tight precision fit between them, a hydraulic press is used to separate them or press them together. The hydraulic press rests on the shop floor. An adjustable steel beam bed is restrained to the lower press frame with heavy steel pins. A hydraulic cylinder and ram is mounted on the top part of the press, with the ram facing downward toward the press bed (Figure 1-8). The component being pressed is placed on the press bed with the appropriate steel supports. A hand-­operated hydraulic pump is mounted on the side of the press. When the handle is pumped, hydraulic fluid is forced into the cylinder, and the ram is extended against the component on the press bed to complete the pressing operation. A pressure gauge on the press indicates the pressure applied from the hand pump to the cylinder. The press frame is designed for a certain maximum pressure. This pressure must not be exceeded during operation.

A hydraulic press is a tool used to remove and install components with a tight press fit.

Figure 1-8  A hydraulic press.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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COMPRESSED AIR EQUIPMENT SAFETY Pneumatic tools are power tools that use compressed air to increase the power and capacity of the tool.

A lift may be called a hoist. Some vehicles have electronic suspension systems. In these cases, the air suspension systems must be electrically disabled by a switch (usually located in the trunk) before lifting the ­vehicle. Not disabling the suspension ­system may cause damage to it. Refer to Today’s TechnicianTM Automotive Suspension Systems for detailed information about air suspension systems.

Tools that use compressed air are called pneumatic tools. Compressed air is used to inflate tires, apply paint, and drive tools. Compressed air can be dangerous when it is not used properly. The shop air supply contains high-pressure air in the shop compressor and air lines. Serious injury or property damage may result from careless operation of compressed air equipment. Follow these guidelines when working with compressed air: 1. Wear safety glasses or a face shield when using pneumatic tools and other compressed air equipment. 2. Wear ear protection when using compressed air equipment. 3. Always maintain air hoses and fittings in good condition. If an end suddenly blows off an air hose, the hose will whip around, and this may cause personal injury or vehicle damage. 4. Do not direct compressed air against the skin. This air may penetrate the skin, ­especially through small cuts or scratches. If compressed air penetrates the skin and enters the bloodstream, it can be fatal or cause serious health complications. Use only air gun nozzles approved by the Occupational Safety and Health Administration (OSHA). 5. Do not use an air gun to blow off clothing or hair. 6. Do not clean the workbench or floor with compressed air. This action may blow very small parts against your skin or into your eye. Small parts or dirt blown by compressed air may cause vehicle damage. For example, if the car in the next stall has the air cleaner removed, a small part may go into the throttle body. When the engine is started, this part or dirt will likely be pulled into the cylinder by engine vacuum and could penetrate the top of a piston. 7. Never spin bearings with compressed air, because the bearing will rotate at an extremely high speed. Under this condition, the bearing may be damaged or it may disintegrate, causing personal injury or other damage. 8. All pneumatic tools must be operated according to the manufacturer’s recommended operating procedure. 9. Follow the equipment manufacturer’s recommended maintenance schedule for all compressed air equipment.

LIFT SAFETY A lift is used to raise a vehicle so a technician can work under the vehicle. The lift arms must be placed under the car at the manufacturer’s recommended lift points. Twin posts are used on some lifts, whereas other lifts have a single post (Figure 1-9). Some lifts have an electric motor that drives a hydraulic pump to create fluid pressure and force the lift upward. Other lifts use air pressure from the shop air supply to force the lift upward. If shop air pressure is used for this purpose, the air pressure is applied to fluid in the lift cylinder. A control lever or switch is placed near the lift. The control lever supplies shop air pressure to the lift cylinder, and the switch turns on the lift pump motor. Always be sure that the safety lock is engaged after the lift is raised. When the safety lock is released, a lever can be operated to slowly lower the vehicle. Be very careful when raising a vehicle on a lift or a hoist. Adapters and hoist plates must be positioned correctly on twin post and rail-type lifts to prevent the vehicle from falling off the lift and causing serious injury to you or severe damage to the vehicle. Improper lift pad placement can also damage the undercarriage of the vehicle. There are specific lift points. These points allow the weight of the vehicle to be evenly supported by the adapters or hoist plates. The correct lift points can be found in the vehicle’s service Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Figure 1-9  A twin post lift.

19 inches (483 mm)

30 inches (762 mm)

Drive on hoist

Frame contact hoist

Floor jack

Outboard twin post hoist

Figure 1-10  Hoisting and lifting points for a typical unibody ­vehicle. Locate your vehicle’s lift points in the service information.

information. Figure 1-10 shows typical locations for frame and unibody cars. These diagrams are for illustration only. Always follow the manufacturer’s instructions. Before operating any lift or hoist, carefully read the operating manual and follow the operating instructions. WARNING  Never use a lift or jack to move something heavier than it is designed for. Always check the rating before using a lift or jack. If a jack is rated for 2 tons, do not attempt to use it for a job requiring 5 tons. It is dangerous for you and the vehicle. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Before driving a vehicle over a lift, position the arms and supports to provide an unobstructed clearance. Do not hit or run over lift arms, adapters, or axle supports. This could damage the lift, vehicle, or tires. WARNING  Never disable the lift locking devices or work under a lift where the safety mechanism is broken. The safety handles or locks prevent the lift from falling if the lift fails.

Position the lift supports to contact the vehicle at its lifting points. Raise the lift until the supports contact the vehicle. Then check the supports to make sure they are in full contact with the vehicle. Jounce the vehicle on the lift to be sure it feels secure. Raise the lift to the desired working height. Make sure the vehicle’s doors, hood, and trunk are closed before raising the vehicle. Never raise a car with someone inside. WARNING Before working under a car, make sure the lift’s locking device is engaged. If the locking device is not engaged, the lift may drop suddenly, resulting in severe personal injury and vehicle damage.

After lifting a vehicle to the desired height, always lower it onto its mechanical safeties. On some vehicles, the removal (or installation) of components can cause a critical shift of the vehicle’s weight, which may cause the vehicle to be unstable on the lift. Refer to the vehicle’s service information for the recommended procedures to prevent this from happening. Make sure tool trays, stands, and other equipment are removed from under the ­vehicle. Never place oxyacetylene torches under a lift. Release the lift’s locking devices according to the instructions before attempting to lower the lift. Refer to Photo Sequence 1 and Photo Sequence 2 for lifting procedures.

PHOTO SEQUENCE 1

Typical Procedure for Lifting a Vehicle on a Hoist

P1-1  Drive the vehicle onto the hoist. Make sure your wheels are centered, and drive slowly. If needed, stick your head out of the window or have an assistant help guide you. Never stand in front of a moving vehicle.

P1-2  Center the vehicle over the hoist, considering the vehicle’s center of gravity and balance point.

P1-3  Make sure that the locks are set and the hoist is level. Always rest the hoist on the locks. Most drive-on lifts are hydraulically lifted, but their locks are air operated.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

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PHOTO SEQUENCE 1 (CONTINUED)

P1-4  Lift the vehicle a couple of inches from the floor. Shake the vehicle while observing it for signs of any movement. If the vehicle is not secure on the hoist or unusual noises are heard while lifting, lower it to the floor and reset the pads.

P1-5  Once the vehicle is at the desired height, lock the hoist. Do not get under the vehicle until the hoist locks have been set.

P1-6  Once the axle is at the height you want it, lower it and rest it on the locks. Most rolling jacks are air operated and have manual locks.

JACK AND JACK STAND SAFETY An automobile can be raised off the ground by a hydraulic jack (Figure 1-11). Jack stands (Figure 1-12) are supports of different heights that sit on the floor. They are placed under a sturdy chassis member, such as the frame or axle housing, to support the vehicle. Like jacks, jack stands also have a capacity rating. Always use the correct rating of jack stand. A floor jack is a portable unit mounted on wheels. The lifting pad on the jack is placed under the chassis of the vehicle, and the jack handle is operated with a pumping action. This jack handle operation forces fluid into a hydraulic cylinder in the jack, and the cylinder extends to force the jack lift pad upward and lift the vehicle. Always be sure that the lift pad is positioned securely under one of the car manufacturer’s recommended lift points. To release the hydraulic pressure and lower the vehicle, the handle or release lever must be turned slowly. The jack should be removed after the jack stands are set in place. This eliminates a hazard, such as a jack handle sticking out into a walkway. A jack handle that is bumped or kicked can cause a tripping accident or cause the vehicle to fall.

Jack stands are used to support raised vehicles. Jack stands are also called safety stands.

A floor jack is a portable hydraulic lifting device that is used to lift part of a vehicle off the ground.

WARNING  Never use a jack by itself to support a vehicle. Always use a jack stand with a jack, and make sure that the jack stands are properly positioned under the vehicle. Jack stands must always be positioned on a concrete floor, not on dirt or in gravel.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 2

Typical Procedure for Lifting a Vehicle on a Drive-On Hoist

P2-1  Drive the vehicle onto the hoist. Make sure your wheels are centered, and drive slow. If needed, stick your head out of the window or have an assistant help guide you. Never stand in front of a moving vehicle.

P2-2  Place a wheel chock behind the other end of the vehicle to ensure it doesn’t roll when being lifted.

P2-3  Raise the vehicle to a comfortable height.

P2-4  Make sure that the locks are set and the hoist is level. Always rest the hoist on the locks. Most drive-on lifts are hydraulically lifted, but their locks are air operated.

P2-5  Position the rolling jacks on a suitable location. Check the service manual for correct locations.

P2-6  Once the axle is to a height you want it, lower it and rest it on the locks. Most rolling jacks are air operated and have manual locks.

Figure 1-11  Typical hydraulic floor jack.

Figure 1-12  Typical jack stands.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

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Accidents involving the use of floor jacks and jack stands may be avoided if these safety precautions are followed: 1. Never work under a vehicle unless jack stands are placed securely under the vehicle chassis and the vehicle is resting on these stands. 2. Prior to lifting a vehicle with a floor jack, be sure that the jack lift pad is positioned securely under a recommended lift point on the vehicle. Lifting the front end of a vehicle with the jack placed under a radiator support may cause severe damage to the radiator and support. 3. Position the jack stands under a strong chassis member such as the frame or axle housing. The jack stands must contact the vehicle manufacturer’s recommended lift points. 4. Since the floor jack is on wheels, the vehicle and jack tend to move as the vehicle is lowered from a floor jack onto jack stands. Always be sure the jack stands remain under the chassis member during this operation, and be sure the jack stands do not tip. All the jack stand legs must remain in contact with the shop floor.

ENGINE LIFT SAFETY If the engine is removed through the hood opening, an engine hoist is used (Figure 1-13). The hoist is attached to the engine by a sling. When attaching the sling, make sure the bolts are strong enough to hold the weight of the engine and are threaded in far enough to prevent the bolts from stripping out. Most service information will provide proper locations for the sling to attach to the engine. The hoist may have adjustable booms and load legs. Adjust the legs out far enough to prevent the engine and hoist from tipping. When adjusting the boom, remember that the farther out it is extended, the lower its lift capacity. After adjusting the legs and boom, make sure the lock pins are properly installed.

An engine hoist may be called a cherry picker or engine crane.

Figure 1-13  An engine hoist. 

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 1

As the engine is being lifted or lowered, stand clear. Never get under an engine supported only by the hoist. Once the engine is out of the vehicle, immediately lower it to the floor or install it onto an engine stand.

CLEANING EQUIPMENT SAFETY

Chemical cleaning uses chemicals to remove grease, scale, rust, paint, or anything else that is causing an issue because of its presence.

All technicians are required to clean parts during their normal work routines. Face shields and protective gloves must be worn while operating cleaning equipment. The solution in hot and cold cleaning tanks may be caustic, and contact between this solution and skin or eyes must be avoided. Parts cleaning often creates a slippery floor, and care must be taken when walking in the parts cleaning area. The floor in this area should be cleaned frequently. When the caustic cleaning solution in hot or cold cleaning tanks is replaced, environmental regulations require that the old solution be handled as hazardous waste. Use caution when placing aluminum or aluminum alloy parts in a cleaning solution. Some cleaning solutions will damage these components. Always follow the cleaning equipment manufacturer’s recommendations. Parts cleaning is a necessary step in most repair ­procedures. Cleaning automotive parts can be divided into three basic categories. Chemical cleaning relies primarily on some type of chemical action to remove dirt, grease, scale, paint, or rust. A combination of heat, agitation, mechanical scrubbing, or washing may also be used to help remove dirt. Chemical cleaning equipment includes small parts washers, hot/cold tanks, pressure washers, spray washers, and salt baths (Figure 1-14). Some parts washers provide electromechanical agitation of the parts to provide improved cleaning action. These parts washers may be heated with gas or electricity, and various waterbased hot tank cleaning solutions are available, depending on the type of metals being

Figure 1-14  This hot tank works like a dishwasher to scrub engine blocks, cylinder heads, and other parts clean. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

cleaned. For example, Kleer-Flo GreasoffTM Number 1 powdered detergent is available for cleaning iron and steel. Non-heated electromechanical parts washers are also available, and these washers use cold cleaning solutions, such as Kleer-Flo DegreasolTM formulas. Many cleaning solutions, such as Kleer-Flo DegreasolTM 99R, contain no ingredients listed as hazardous by the Environmental Protection Agency’s Resource Conservation and Recovery Act (RCRA). This cleaning solution is a blend of sulfur-free hydrocarbons, ­wetting agents, and detergents. DegreasolTM 99R does not contain aromatic or chlorinated solvents, and it conforms to California’s Rule 66 for clean air. Always use the cleaning solution recommended by the equipment manufacturer. Some parts washers have an agitated immersion chamber under the shelves, which provides thorough parts cleaning. Folding work shelves provide a large upper cleaning area with a constant flow of solution from the dispensing hose. This cold parts washer operates on DegreasolTM 99R or similar cleaning solution (Figure 1-15). An aqueous parts cleaning tank uses a water-based, environmentally friendly cleaning solution such as GreasoffTM 2 rather than traditional solvents. The immersion tank is heated and agitated for effective parts cleaning. A sparger bar pumps a constant flow of cleaning solution across the surface to push floating oils away, and an integral skimmer removes these oils. This action prevents floating surface oils from redepositing on cleaned parts. Many shops have contracts with chemical companies, which regularly send personnel to service the machine and refresh the solvent. Many of these cleaning chemicals are hazardous waste and must be handled properly by qualified people. Thermal cleaning relies on heat, which bakes off or oxidizes the dirt. Thermal cleaning leaves an ash residue on the surface that must be removed by an additional cleaning process, such as airless shot blasting or spray washing. Abrasive cleaning relies on physical abrasion to clean the surface. This includes everything from a wire brush to glass bead blasting, airless steel shot blasting, abrasive

17

Thermal cleaning relies on heat to break the dirt and grease from a part. Abrasive cleaning uses an abrasive product to clean the surface of grease, rust, and dirt.

Figure 1-15  This parts washer sends solvent through the nozzle where you can direct it across the dirty component. Wear gloves and use a brush to thoroughly clean the part. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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tumbling, and vibratory cleaning. Chemical in-tank solution sonic cleaning might also be included here because it relies on the scrubbing action of ultrasonic sound waves to loosen surface contaminants.

CUSTOMER CARE  Prior to disconnecting the battery on some late-model v­ ehicles, it may be necessary to connect an auxiliary power supply to the cigarette lighter socket to maintain power to the onboard computer memories. If an auxiliary power supply is not available, record the radio presets and set the radio and the clock before returning the vehicle to the customer. If battery power has been disconnected from the engine computer, the powertrain control module (PCM), some of the learned memory will be lost. Until the vehicle has been driven several miles, it may not perform exactly the same as it did prior to disconnecting the battery. Be sure to explain this to the customer; he or she should just drive the vehicle normally for a day or two and then the vehicle will perform as usual.

WARNING  When removing and replacing an engine, always disconnect the negative battery cable before starting to work on the vehicle. If the positive cable is removed first, the wrench may slip and make contact between the positive battery terminal and ground. This action may overheat the wrench and burn the technician’s hand or possibly result in the battery exploding. When installing the engine, do not reconnect the negative battery cable until the installation is complete and you are ready to start the engine. The Occupational Safety and Health Administration (OSHA) is a part of the U.S. ­government tasked with protecting the health and safety of workers. Right-to-Know laws inform workers regarding exposure to hazardous materials. Safety Data Sheets (SDS) provide extensive information about ­hazardous materials. Workplace Hazardous Materials Information Systems (WHMIS) list information about ­hazardous materials.

A wide variety of chemical solvents and aerosol sprays are used to clean parts and free up rusted components. Most of these are hazardous to your health and safety. You should understand the risks involved with these products before using them. The Occupational Safety and Health Administration (OSHA) established that every employee in a shop be protected by Right-to-Know laws concerning hazardous materials and wastes. The general intent of these laws is for employers to provide a safe workplace, as it relates to hazardous materials. All employees must be trained about their rights under the legislation, including the nature of the hazardous chemicals in their workplace, the labeling of chemicals, and the information about each chemical listed and described on Safety Data Sheets (SDS). These sheets are available from the manufacturers and suppliers of the chemicals. They detail the chemical composition and precautionary information for all products that can present health or safety hazards. An up-to-date notebook containing the SDS for every hazardous material should be available in each automotive repair shop. Employees must be familiar with the intended purposes of the material, the recommended protective equipment, accident and spill procedures, and any other information regarding the safe handling of hazardous materials. This training must be given to all employees who will work with these materials. The Canadian equivalents to the SDS are called Workplace Hazardous Materials Information Systems (WHMIS). Read through the SDS on the various chemicals used in the shop to learn about the protective equipment required for handling, explosion and fire hazards, incompatible materials, health hazards and first aid procedures, safe handling precautions, and spill and leak procedures. WARNING  Always wear a face shield or safety glasses to avoid dangerous ­contact with your eyes. Permanent damage to your eyes can result from exposure to certain chemicals.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Figure 1-16  Flammable liquids should be stored in safety-approved containers.

■■ ■■ ■■ ■■ ■■ ■■ ■■

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Figure 1-17  Store combustible materials in approved safety cabinets.

In general, follow these guidelines when using toxic chemicals and solvents: Always wear appropriate eye protection. Handle all chemical solvents with care to avoid spillage. Keep all solvent containers closed when not in use. Be careful when transferring flammable and toxic materials; only use approved ­storage containers (Figure 1-16). Promptly discard or clean all empty solvent containers; the fumes may be flammable. Never use torches or smoke near flammable chemicals and solvents, including battery acid. Store solvents, chemicals, and other flammable materials in approved safety cabinets (Figure 1-17).

HAZARDOUS WASTE An automotive repair shop generates hazardous and environmentally damaging wastes. These include used engine oil, brake fluid, antifreeze, power steering fluid, and transmission fluids. Used oil filters must also be handled properly to minimize their contamination of the environment. The U.S. Environmental Protection Agency (EPA) and Canadian Environmental Assessment Agency (CEAA) are national agencies that offer guidelines and set regulations for the handling of hazardous waste. Many states and provinces have regulations in addition to those that are instituted by the EPA; be sure to check all applicable laws before disposing of waste that could be hazardous. Be careful when draining fluids from a vehicle. Do not let fluid stream to the ground and get into the shop drains. Use an appropriate absorbent to promptly clean up spills. Fluids left on the floor create a slipping hazard. Some absorbents may become hazardous waste, depending on the fluid they have absorbed. Check all applicable regulations before disposing of this material. Store used fluids in approved containers. They should be clearly labeled and sealed after each use. Do not mix fluids into one container. Used antifreeze should be recycled whenever possible; if not, it must be disposed of as a hazardous waste. Some shops have in-house antifreeze recovery, recycling, and refilling equipment for cooling system service. Used engine oil is also a hazardous waste that must be recycled or disposed of properly. Some shops use heating systems that are fueled by used engine oil. Be sure that the storage container is in good condition; check regularly for leaks. Use an above-ground storage

The Environmental Protection Agency (EPA) is a governmental department dedicated to reducing pollution and improving environmental quality.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 1

container whenever possible. Used oil filters should be crushed or drained for 12 hours to remove as much of the toxic oil as possible. Punch a small hole in the domed end of the filter to assist the draining. Recycle used oil filters whenever possible.

VEHICLE OPERATION

Carbon monoxide (CO) is an odorless, poisonous gas. When it is breathed in, it can cause headaches, ­nausea, ringing in your ears, tiredness, and heart ­flutter. Heavy amounts of CO can kill you.

When the customer brings a vehicle in for service, certain shop safety guidelines should be followed. For example, do a vehicle walk around noting on the work order any damage and inspecting tire condition and the oil level. Then when moving a car into the shop, check the brakes before beginning. Always buckle the safety belt. Drive carefully in and around the shop. Make sure that no one is near, the way is clear, and no tools or parts are under the car before you start the engine. When road testing the car, obey all traffic laws. Drive only as far as is necessary to check the automobile. Never make excessively quick starts, turn corners too quickly, or drive faster than conditions allow. If the engine must be running while working on the car, block the wheels to prevent the car from moving. Place the transmission into park for automatic transmissions or in neutral for manual transmissions. Set the emergency brake. Never stand directly in front of or behind a running vehicle. Run the engine only in a well-ventilated area, to avoid the danger of poisonous carbon monoxide (CO) in the engine exhaust. If the shop is equipped with an exhaust ventilation system (Figure 1-18), use it. If not, use a hose and direct the exhaust out of the building. WARNING To prevent personal injury, never run the engine in a vehicle inside the shop without an exhaust hose connected to the tailpipe.

Vehicle exhaust contains small amounts of carbon monoxide, which is a poisonous gas. Strong concentrations of carbon monoxide may be fatal for human beings. All shop personnel are responsible for air quality in the shop. Shop management is responsible for providing an adequate exhaust system to remove exhaust fumes from the maximum ­number of vehicles that may be running in the shop at the same time. Technicians should never run a vehicle in the shop unless a shop exhaust hose is installed on the tailpipe of the vehicle. The exhaust fan must be switched on to remove exhaust fumes. If shop heaters or furnaces have restricted chimneys, they release carbon monoxide emissions into the shop air. Therefore, chimneys should be checked periodically for restriction and proper ventilation.

Figure 1-18  Exhaust vent hose to a tailpipe. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Monitors are available to measure the level of carbon monoxide in the shop. Some of these monitors read the amount of carbon monoxide present in the shop air, and other monitors provide an audible alarm if the concentration of carbon monoxide exceeds the danger level. Diesel exhaust contains some carbon monoxide, but particulates are also present in the exhaust from these engines. Particulates are small carbon particles, which can be harmful to the lungs. The sulfuric acid solution in car batteries is a very corrosive, poisonous liquid. If a battery is charged with a fast charger at a high rate for a period of time, the battery becomes hot, and the sulfuric acid solution begins to boil. Under this condition, the battery may emit a strong sulfuric acid smell, and these fumes may be harmful to the lungs. If this condition occurs in the shop, the battery charger should be turned off or the charger rate should be reduced considerably. When an automotive battery is charged, hydrogen gas and oxygen gas escape from the battery. If these gases are combined, they form water, but hydrogen gas by itself is very explosive. While a battery is charged, sparks, flames, and other sources of ignition must not be allowed near the battery.

21

Particulates are small carbon particles present in diesel exhaust and considered to be pollutants. Sulfuric acid is a ­corrosive acid used in automotive batteries.

WORK AREA SAFETY WARNING  Always be familiar with evacuation routes and where to gather outside the building. WARNING  Always know the location of all safety equipment in the shop, and be familiar with the operation of this equipment.

Your work area should be kept clean and safe. The floor and bench tops should be kept clean, dry, and orderly. Any oil, coolant, or grease on the floor can make it slippery. Slips can result in serious injuries. To clean up oil, use a commercial oil absorbent. Keep all water off the floor. Water is slippery on smooth floors, and electricity flows well through water. Aisles and walkways should be kept clean and wide enough to move through easily. Make sure the work areas around machines are large enough to operate the machine safely (Figure 1-19).

Shop rules, vehicle operation in the shop, and shop housekeeping are serious business. Each year a significant number of technicians are injured, and vehicles are damaged, by ­disregarding shop rules, careless vehicle operation, and sloppy housekeeping.

Figure 1-19  Safety zone markings. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Proper ventilation of space heaters, used in some shops, is necessary to reduce the CO levels in the shop. Also, proper ventilation is very important in areas where volatile solvents and chemicals are used. (A volatile liquid is one that vaporizes very quickly.) Keep an up-to-date list of emergency telephone numbers clearly posted next to the telephone. These numbers should include a doctor, hospital, and fire and police departments. Also, the work area should have a first-aid kit for treating minor injuries. There should also be eye flushing kits readily available. Gasoline is a highly flammable volatile liquid. Always keep gasoline or diesel fuel in an approved safety can, and never use it to clean your hands or tools. Oily rags should also be stored in an approved metal container. When these oily, greasy, or paint-soaked rags are left lying about or are not stored properly, they can cause spontaneous combustion. Spontaneous combustion results in a fire that starts by itself, without a match. Make sure that all drain covers are snugly in place. Open drains or covers that are not flush to the floor can cause toe, ankle, and leg injuries. Know where the fire extinguishers are and what types of fires they put out (Figure 1-20). A multipurpose dry chemical fire extinguisher will put out ordinary combustibles,

Class

A

Fires

Class of Fire

Typical Fuel Involved

Type of Extinguisher

For Ordinary Combustibles Put out a Class A fire by lowering its temperature or by coating the burning combustibles.

Wood Paper Cloth Rubber Plastics Rubbish Upholstery

Water*1 Foam* Multipurpose dry chemical4

For Flammable Liquids Put out a Class B fire by smothering it. Use an extinguisher that gives a blanketing, flame-interrupting effect; cover whole flaming liquid surface.

Gasoline Oil Grease Paint Lighter fluid

Foam* Carbon dioxide5 Halogenated agent6 Standard dry chemical2 Purple K dry chemical3 Multipurpose dry chemical4

For Electrical Equipment Put out a Class C fire by shutting off power as quickly as possible and by always using a nonconducting extinguishing agent to prevent electric shock.

Motors Appliances Wiring Fuse boxes Switchboards

Carbon dioxide5 Halogenated agent6 Standard dry chemical2 Purple K dry chemical3 Multipurpose dry chemical4

For Combustible Metals Put out a Class D fire of metal chips, turnings, or shavings by smothering or coating with a specially designed extinguishing agent.

Aluminum Magnesium Potassium Sodium Titanium Zirconium

Dry power extinguishers and agents only

(green)

Class

B

Fires

(red)

Class

C

Fires

(blue)

Class

D

Fires

(yellow)

*Catridge-operated water, foam, and soda-acid types of extinguishers are no longer manufactured. These extinguishers should be removed from service when they become due for their next hydrostatic pressure test. Notes: (1) Freezes in low temperatures unless treated with antifreeze solution, usually weighs over 20 pounds (9 kg), and is heavier than any other extinguisher mentioned. (2) Also called ordinary or regular dry chemical (sodium bicarbonate). (3) Has the greatest initial fire-stopping power of the extinguishers mentioned for class B fires. Be sure to clean residue immediately after using the extinguishers so sprayed surfaces will not be damaged (potassium bicarbonate). (4) The only extinguishers that fight A, B, and C classes of fires. However, they should not be used on fires in liquefied fat or oil of appreciable depth. Be sure to clean residue immediately after using the extinguisher so sprayed surfaces will not be damaged (ammonium phosphates). (5) Use with caution in unventilated, confined spaces. (6) May cause injury to the operator if the extinguishing agent (a gas) or the gases produced when the agent is applied to a fire is inhaled.

Figure 1-20  Guide to fire extinguisher selection.  Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

f­ lammable liquids, and electrical fires. Never put water on a gasoline fire. The water will just spread the fire. Use a fire extinguisher to smother the flames. Remember, during a fire, never open doors or windows unless it is absolutely necessary; the extra draft will only make the fire worse. A good rule is to call the fire department first and then attempt to extinguish the fire. To extinguish a fire, stand 6–10 feet from the fire. Hold the extinguisher firmly in an upright position. Aim the nozzle at the base and use a side-to-side motion, sweeping the entire width of the fire. Stay low to avoid inhaling the smoke. If it gets too hot or too smoky, get out. Remember, never go back into a burning building for anything. Shops that employ ASE-certified technicians display an official ASE blue seal of excellence. This blue seal increases the customer’s awareness of the shop’s commitment to quality service and the competency of certified technicians.

HYBRID VEHICLE HIGH-VOLTAGE SAFETY Hybrid vehicles contain high-voltage battery packs that can be rated over 600 volts. It is necessary to be able to identify the high-voltage components and their conductors. The cables are thicker and are often orange in color. Mild hybrid vehicles tend to have blue insulated cables indicating higher voltage. Insulated linesman gloves must be worn when working around the high-voltage system. The gloves must be “Class 0” rated for 1,000 volts. It is recommended that leather gloves be worn over the rubber gloves to prevent tears. The gloves must be checked before each use for leaks and should be recertified every 6 months. To check the gloves, roll the sleeve so the gloves hold air. Make sure the gloves stay slightly inflated. If they deflate they must be replaced. Precautions to be aware of while working on or around HEV high-voltage systems are the following: 1. Have the proper training before servicing. 2. Follow the manufacturer’s recommended service procedures. HEV High-Voltage Warning Label (Figure 1-21). 3. Some examples of precautions are as follows: Make sure the system is off with the key a distance from the vehicle. Disconnect the 12-volt auxiliary battery and wait the recommended amount of time for any capacitors to discharge (typically 10 minutes). Disconnect the service plug or switch while wearing HV gloves. Keep others away from the vehicle during service. After powering down the high-voltage system check for the presence of remaining power using a CAT III–rated voltmeter with CAT III leads.

Figure 1-21  HEV High-voltage warning label. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Don’t push an electric or a hybrid vehicle. Use insulated tools when working on high-voltage system fasteners. High-voltage batteries need to have efficient cooling and ventilation; otherwise, they will be damaged at high temperatures.

CASE STUDY A technician installed a rebuilt engine in a vehicle. Before completing the installation, the ­technician reconnected the negative battery cable. While installing the drive belts, the technician leaned on top of the alternator with one arm. The protective boot had been pushed aside on the alternator battery terminal, and the technician’s metal wristwatch strap completed the circuit from the alternator battery terminal to ground. This action caused a very high current flow through the wristwatch strap and severely burned the technician’s arm. From this experience, the technician learned the following: 1. Do not wear a wristwatch while working in the shop. 2. When installing an engine, do not reconnect the battery until the installation is complete and you are ready to start the engine.

ASE-STYLE REVIEW QUESTIONS 1. Technician A says that it is recommended that you wear shoes with nonslip soles in the shop. Technician B says that steel-toed shoes offer the best foot protection. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 2. Technician A says that some machines can be routinely used beyond their stated capacity. Technician B says that a power tool can be left running unattended if the technician puts up a power “on” sign. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 3. Technician A ties his long hair behind his head while working in the shop. Technician B covers her long hair with a brimless cap. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Technician A uses compressed air to blow dirt from his clothes and hair. Technician B says that this should only be done outside. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. While discussing the proper way to lift a heavy object, Technician A says that you should bend at your knees if you are going to pick up a heavy object. Technician B says that if the object is too heavy, then a wheel dolly should be used. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 6. While discussing shop cleaning equipment safety, Technician A says that some hot tanks contain caustic solutions. Technician B says that some metals such as ­aluminum may dissolve in hot tanks. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

7. While discussing shop rules, Technician A says that breathing carbon monoxide may cause arthritis. Technician B says that breathing carbon monoxide may cause headaches. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. While discussing air quality, Technician A says that a restricted chimney on a shop furnace may cause carbon monoxide gas in the shop. Technician B says that monitors are available to measure the level of carbon monoxide in the shop air. Who is correct? A. A only C. ­Both A and B B. B only D. Neither A nor B

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9. While discussing air quality, Technician A says that a battery gives off ­hydrogen gas during the charging process. Technician B says that a battery gives off oxygen gas during the charging process. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. While discussing hazardous materials, Technician A says that used engine oil is considered a hazardous waste. Technician B says that spill and leak procedures are covered in the SDS. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. Technician A says that compressed air can ­penetrate your skin if you spray yourself with an air nozzle. Technician B says that if compressed air gets into your bloodstream it can be fatal. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that you should wear Z-87.1 safety glasses while working on or under vehicles. Technician B says that if you are hammering on a component on the bench, you should take your safety glasses off so you can see it better. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

4. Technician A says to lift vehicles by the front and rear frames. Technician B says that some vehicles will permanently twist if lifted improperly. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. Technician A says that high-voltage cables on all hybrid vehicles can be identified by their orangecolored insulation. Technician B says some hybrid vehicles’ highvoltage systems remain powered up even with the engine off. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says that when a fire starts, it is important to open the bay doors for adequate ventilation. Technician B says that a Class C fire extinguisher can be used for most ordinary combustibles. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Name ______________________________________

Date __________________

SHOP SAFETY SURVEY As a professional technician, safety should be one of your first concerns. This job sheet should increase your awareness of shop safety rules and safety equipment. As you survey your shop area and answer the following questions, you should learn how to evaluate the safeness of your workplace. NATEF Correlation This job sheet addresses the following RST tasks: Shop and Personal Safety, Task #1 Identify general shop safety rules and procedures. Shop and Personal Safety, Task #5 Utilize proper ventilation procedures for working within the lab/shop area. Shop and Personal Safety, Task #6 Identify marked safety areas. Shop and Personal Safety, Task #7 Identify the location and the types of fire extinguishers and other fire safety equipment; demonstrate knowledge of the procedures for using fire extinguishers and other fire safety equipment. Shop and Personal Safety, Task #8 Identify the location and use of eyewash stations. Shop and Personal Safety, Task #9 Identify the location of the posted evacuation routes. Shop and Personal Safety, Task #10 Comply with the required use of safety glasses, ear protection, gloves, and shoes during lab/shop activities. Shop and Personal Safety, Task #11 Identify and wear appropriate clothing for lab/shop activities. Shop and Personal Safety, Task #12 Secure hair and jewelry for lab/shop activities. Tools and Materials • Z87.1 safety glasses Procedure Your instructor will review your progress throughout this worksheet and should sign off on the sheet when you complete it. 1. Before you begin to evaluate your work area, evaluate yourself. Are you dressed to work safely? h Yes  h No If no, what is wrong? ______________________________________________________ 2. Are your safety glasses OSHA approved? Do they have side protection shields?

h Yes  h No h Yes  h No

3. What is the stamped ANSI rating on your glasses? _______________ 4. Describe the location for other personal safety equipment in the shop, such as ear protection, gloves, face shields, etc. _________________________________________________________________________ _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

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Chapter 1

5. When you are working in the shop, jewelry should be removed and long hair should be tied up. Are you prepared to work in a lab/shop environment? _______________ 6. Look around the shop, and note any area that poses a potential safety hazard or is an area that you should be aware of. _________________________________________________________________________ _________________________________________________________________________ Any true hazards should be brought to the attention of the instructor immediately. 7. Are there safety areas marked around grinders and other machinery?

h Yes  h No

8. What is the line air pressure in the shop? _______________ psi What should it be? _______________ psi 9. Where are the tools stored in the shop? _________________________________________________________________________ _________________________________________________________________________ 10. If you could, how would you improve the tool storage area? _________________________________________________________________________ _________________________________________________________________________ 11. What types of hoists are used in the shop? _________________________________________________________________________ _________________________________________________________________________ 12. Where is/are the first aid kit(s) kept in the work area? _________________________________________________________________________ _________________________________________________________________________ 13. What is the shop’s procedure for dealing with an accident? _________________________________________________________________________ _________________________________________________________________________ 14. Where are the fire extinguishers located in your shop? _________________________________________________________________________ _________________________________________________________________________ 15. What class of fires do they extinguish? ________________________________________ 16. Describe the procedure for using a fire extinguisher. _________________________________________________________________________ _________________________________________________________________________ 17. The exhaust from a vehicle’s tailpipe can be hazardous if not properly vented outside. Describe what is hazardous about the exhaust and how the shop you are working in deals with safely removing it. _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

18. Where is the electrical emergency shutoff? _____________________________________ 19. Describe the location(s) of the eye wash station(s). _________________________________________________________________________ _________________________________________________________________________ 20. Is the eye wash station in clear view?

h Yes  h No

21. Look for the posted evacuation routes. You will need to know where these are when there is a true emergency. Describe where they are located. _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

29

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Name ______________________________________

Date __________________

PROPER HANDLING OF HAZARDOUS MATERIALS Upon completion of this job sheet, you should be familiar with your shop’s procedures for handling hazardous materials and hazardous waste. You should also be able to access information from the SDS book in your shop or as your instructor shows you. NATEF Correlation This job sheet addresses the following RST tasks: Shop and Personal Safety, Task #15 Locate and demonstrate knowledge of Safety Data Sheets (SDS). Tools and Materials • Aerosol solvent or other chemical • Used engine oil container • Coolant container or recovery system • Z87.1 safety glasses • SDS book Procedure 1. Do you have your safety glasses on?

h Yes  h No

2. Locate the cabinet for flammable chemicals and solvent materials. Note all markings on the cabinet and/or storage area. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Remove an aerosol chemical spray (or other solvent) can from the chemical storage cabinet. Is it clearly labeled?

h Yes  h No

What is the name of the product? _________________________________________________________________________ 4. Locate the SDS book. Is it labeled and stored in an accessible location? h Yes  h No Where is it located? ________________________________________________________ 5. Look up the SDS for the chemical spray you have taken out. Is the SDS available?

h Yes  h No

Briefly describe the health hazards and safety precautions for this product. _________________________________________________________________________ _________________________________________________________________________ 6. Where is the used oil storage receptacle located? _________________________________________________________________________ Is it clearly labeled?

h Yes  h No

Is it properly sealed?

h Yes  h No

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

2

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Chapter 1

7. How does your shop deal with used oil filters? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. How does your shop deal with used coolant? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 9. How does your shop deal with used oil? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Name ______________________________________

Date __________________

JOB SHEET

3

USING FLOOR JACKS AND JACK STANDS Upon completion of this job sheet, you should be able to properly demonstrate how to lift a vehicle using a floor jack and pair of jack stands. NATEF Correlation This job sheet addresses the following RST tasks: Shop and Personal Safety, Task #3 Identify and use proper placement of floor jacks and jack stands. Tools and Materials • Floor jack • Jack stands • Wheel chocks Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

33

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Place the vehicle in park (or gear if manual transmission), and engage parking brake.

h

2. Decide which end of the vehicle you will be lifting, and then position the wheel chocks behind the tires on the opposite end.

h

3. Where is a suitable location for you to place the floor jack on this vehicle?

h

4. Position the floor jack in a suitable location.

h

5. Raise the vehicle with the floor jack.

h

6. Where is a suitable location for you to place the jack stands on this vehicle?

h

7. Position the jack stands in a suitable location. Make sure they are in the exact same position on the left and right sides and at the same height.

h

8. Slowly lower the floor jack so that the vehicle rests on the jack stands.

h

9. Now raise the vehicle back up, remove the jack stands, and lower the vehicle.

h

10. What was the most difficult part of this activity?

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Name ______________________________________

Date __________________

LIFTING A UNIBODY VEHICLE Upon completion of this job sheet, you should be able to properly demonstrate how to lift a unibody vehicle. NATEF Correlation This job sheet addresses the following RST task: Shop and Personal Safety, Task #4 Identify and use proper procedures for safe lift operation. Tools and Materials • Unibody vehicle • Shop lift Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Locate the instruction guide for the lift you are using, and read through the instructions. Explain the operation of the lift and its safety mechanism to your instructor. Is the student’s explanation satisfactory? h Yes  h No 2. Locate the lift points for the vehicle you are working on, and describe them. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Place the lift pads under the designated spots, and raise the lift until the pads are just contacting the vehicle. Are they properly positioned? h Yes  h No If not, lower the vehicle and reposition the pads. 4. Raise the vehicle 1 foot off the floor, and jounce the vehicle. Listen for any unusual noises, and watch for improper movement. Describe your results. _________________________________________________________________________ _________________________________________________________________________ Have your instructor check your work. Is the vehicle secure on the lift?  h Yes  h No 5. Raise the vehicle overhead, and engage any manual locks. Does your lift have manual locks?

h Yes  h No

6. Describe the procedure for engaging the lift locks. _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

35

JOB SHEET

4

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Chapter 1

7. With the hoist locks engaged, slowly lower the vehicle so that it is resting on the locks. Do all of the locks engage and hold the vehicle evenly? h Yes  h No 8. Identify as many of the components under the vehicle as possible. _________________________________________________________________________ _________________________________________________________________________ 9. Make sure everyone and everything is clear of the vehicle. Describe the procedure to disengage the lift locks. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Lower the vehicle to the floor and remove the lift arms from under the vehicle. Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Safety and Shop Practices

Name ______________________________________

Date __________________

LIFTING A BODY ON FRAME VEHICLE Upon completion of this job sheet, you should be able to properly demonstrate how to lift a body on frame vehicle. NATEF Correlation This job sheet addresses the following RST task: Shop and Personal Safety Task 4 Identify and use proper procedures for safe lift operation. Tools and Materials • Body on frame vehicle • Shop lift Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Locate the instruction guide for the lift you are using, and read through the instructions. Explain the operation of the lift and its safety mechanism to your instructor. Is the student’s explanation satisfactory? h Yes  h No 2. Locate the lift points for the vehicle you are working on, and describe them. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Place the lift pads under the designated spots, and raise the lift until the h Yes  h No pads are just contacting the vehicle. Are they properly positioned? If not, lower the vehicle and reposition the pads. 4. Raise the vehicle 1 foot off the floor, and jounce the vehicle. Listen for any unusual noises, and watch for improper movement. Describe your results. _________________________________________________________________________ Have your instructor check your work. Is the vehicle secure on the lift? h Yes  h No 5. Raise the vehicle overhead, and engage any manual locks. Does your lift have manual locks?

h Yes  h No

6. Describe the procedure for engaging the lift locks. _________________________________________________________________________ _________________________________________________________________________ 7. With the hoist locks engaged, slowly lower the vehicle so that it rests on the locks. Do all of the locks engage and hold the vehicle evenly?

h Yes  h No

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

5

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Chapter 1

8. Identify as many of the components under the vehicle as possible. _________________________________________________________________________ _________________________________________________________________________ 9. Make sure everyone and everything is clear of the vehicle. Describe the procedure to disengage the lift locks. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Lower the vehicle to the floor and remove the lift arms from under the vehicle. Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 2

ENGINE REBUILDING TOOLS AND SKILLS

Upon completion and review of this chapter, you should understand and be able to describe: ■■

■■ ■■

■■ ■■ ■■

The importance of safely using the appropriate tools and equipment and caring for them. The purpose and use of precision ­measuring instruments. The purpose of special measuring instruments, such as the telescoping gauge, small-hole gauge, valve guide bore gauge, valve seat runout gauge, and cylinder bore dial gauge. The types of tools used for cylinder head reconditioning. The tools and equipment used to recondition the engine block. The purpose and use of connecting rod and piston reconditioning equipment and tools.

■■

■■

■■ ■■

■■ ■■

The purpose of special hand tools, including torque wrenches, torque angle gauges, ring expanders, ringgroove cleaners, and ring compressors. The purpose and use of a scan tool for basic engine diagnostics. The importance of how math is used in engine rebuilding and measuring. How to research applicable vehicle and service information. The importance of professionalism and responsibility in repairing and rebuilding engines. The typical agreements in the employer/employee relationship. The challenge and benefits of ASE certification.

Terms To Know Align hone Aligning bar Belt surfacer Boring Broach Calipers Compression gauge Cylinder bore dial gauge Cylinder leakage test Diagnostic link connector (DLC) Diagnostic trouble code (DTC) Dial calipers Dial indicators

Engine dynamometer Exhaust gas analyzer Feeler gauge Flat rate pay Fuel-pressure gauge Knurling kPa Machinist’s rule Malfunction indicator light (MIL) Meter Microinch Micrometer Misfire

National Institute of Automotive Service Excellence (ASE) Noid light OBD II (On Board Diagnostics) Out-of-round gauge Plastigage Powertrain control module (PCM) Profilometer psi Ridge reamer Rod aligner Rod honer

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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40

Chapter 2 Scale Scan tool Small-hole gauge Straight time pay Surface grinder Telescoping gauges

Torque plate Torque-to-yield Torque wrench United States Customary (USC) Valve guide bore gauge

Valve seat runout gauge Valve spring tension testers Vernier calipers Warranty repair

INTRODUCTION During the process of rebuilding or repairing an automotive engine, today’s technician will be required to use some specialized tools. Most engine components require accurate measuring to determine if they are within factory specifications. These include the cylinder bores, crankshaft, crankshaft bores, camshaft bores, connecting rod journals, valve guides, and oil pump gears, to name a few. To perform this task, today’s technician must be able to use a variety of measuring tools properly. If wear is outside of specifications, some components may be reconditioned. Special equipment is available to recondition crankshafts, camshafts, connecting rods, valve faces, valve seats, and several other engine components. These operations require the use of line bores, valve machines, grinders, and other specialty tools. Before you can determine if engine components are within specifications, you must be able to locate these details in the service information. The service information is an invaluable tool. Repairing and rebuilding today’s highly technical engines is challenging and rewarding work. To succeed as an engine repair technician, you will need to develop numerous personal skills and excellent work habits. Communication skills, professionalism, critical thinking, and attention to detail are just a few of the critical skills required for success in the field. Expertise comes from a combination of well-honed technical and personal talents. This chapter introduces you to many of the special measuring tools, hand tools, and equipment used to repair or recondition an engine. Many of these tools are essential to properly rebuild the engine. Some are designed for a specific function and may not be required, but make the job faster and easier. A study into the use of service information will assist you in locating the information you need. Finally, we’ll discuss how you can become a successful, professional technician in today’s repair facilities.

UNITS OF MEASURE The United States Customary (USC) ­measuring system is commonly referred to as the English system.

The metric system’s real name is the international system (SI).

Two systems of weights and measures are commonly used in the United States. One system of weights and measures is the United States Customary (USC) system. Well-known measurements for length in the USC system are the inch, foot, yard, and mile. In this system, the quart and gallon are common measurements for volume, and ounce, pound, and ton are measurements for weight. A second system of weights and measures is referred to as the metric system. In the USC system, the basic linear measurement is the yard, whereas the corresponding linear measurement in the metric system is the meter (Figure 2-1). Each unit of measurement in the metric system is related to the other metric units by a factor of 10. Thus every metric unit can be multiplied or divided by 10 to obtain larger units (multiples)

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills Yardstick

1 2 3 4 5 6 10

20

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 30

40

50

60

70

80

90

Meter stick

Figure 2-1  A meter is slightly longer than a yard.

or smaller units (submultiples); for example, the meter may be divided by 10 to obtain centimeters (1/100 meter) or millimeters (1/1,000 meter). The U.S. government passed the Metric Conversion Act in 1975 in an attempt to move American industry and the general public to accept and adopt the metric system. The automotive industry has adopted the metric system, and in recent years, most bolts, nuts, and fittings on vehicles have been changed to metric. Some older domestic vehicles have a mix of USC and metric bolts. Import vehicles have used the metric system for many years. Although the automotive industry has changed to the metric system, the general public in the United States has been slow to convert from the USC system to the metric system. One of the factors involved in this change is cost. The cost to change every highway distance and speed sign in the United States to be in kilometers would be great. Service technicians must be able to work with both the USC and the metric system. One meter (m) in the metric system is equal to 39.37 inches (in.) in the USC system. Some common equivalents between the metric and USC systems are as follows: 1 meter (m) 5 39.37 inches

1 in.-lb. 5 0.112 Nm

1 centimeter (cm) 5 0.3937 inch

1 in. Hg 5 3.38 kilopascals (kPa)

1 millimeter (mm) 5 0.03937 inch

1 psi 5 6.89 kPa

1 inch 5 2.54 cm

1 mile 5 1.6 kilometers (km)

1 inch 5 25.4 mm

1 horsepower (hp) 5 0.746 kilowatt (kW)

One meter is a little more than 3 inches ­longer than a yard.

1 ft.-lb.5 1.35 newton meters (Nm) degrees Fahrenheit (°F) 5 232 divided by 1.8 5 degrees Celsius (°C) for example, 2128F232 5 180 divided by 1.8 5 1008C

Appendix D provides a more comprehensive conversion chart. SERVICE TIP  A metric conversion calculator provides fast, accurate ­metric-to-USC conversions or vice versa.

In the USC system, phrases such as 1/8 of an inch are used for measurements. The metric system uses a set of prefixes; for example, in the word kilometer, the prefix kilo

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Chapter 2

indicates one thousand, and this prefix indicates there are one thousand meters in a ­kilometer. Common prefixes in the metric system are as follows: Name

Symbol

Meaning

mega

M

one million

kilo

k

one thousand

hecto

h

one hundred

deca

da

ten

deci

d

one tenth of

centi

c

one hundredth of

milli

m

one thousandth of

micro

M

one millionth of

Measurement of Mass In the metric system, mass is measured in grams, kilograms, or tonnes. One thousand grams (g) 5 1 kilogram (kg). In the USC system, mass is measured in ounces, pounds, or tons. When converting pounds to kilograms, 1 pound 5 0.453 kilogram.

Measurement of Length In the metric system, length is measured in millimeters, centimeters, meters, or kilometers. Ten millimeters (mm) 5 1 centimeter (cm). In the USC system, length is measured in inches, feet, yards, or miles. When distance conversions are made between the two systems, some of the conversion factors are the following: 1 1 1 1

inch 5 25.4 millimeters foot 5 30.48 centimeters yard 5 0.91 meter mile 5 1.60 kilometers

Measurement of Volume In the metric system, volume is measured in milliliters, cubic centimeters, and liters. One cubic centimeter 5 1 milliliter. If a cube has a length, depth, and height of 10 centimeters (cm), the volume of the cube is 10 cm 3 10 cm 3 10 cm 5 1,000 cm 3 5 1 liter . When ­volume conversions are made between the two systems, 1 cubic inch 5 16.38 cubic centimeters. If an engine has a displacement of 350 cubic inches, 350 3 16.38 5 5,733 cubic centimeters, and 5,733/1,000 5 5.7 liters.

ENGINE DIAGNOSTIC TOOLS Today’s technician must keep up not only with changes in automotive technology, but also with new testing procedures and specialized diagnostic equipment. To be successful, a shop must continuously invest in the equipment and the training necessary to troubleshoot today’s electronic engine systems. Not all engine performance problems are related to electronic control systems. Therefore, technicians still need to understand basic engine tests. These tests are an important part of modern engine diagnosis. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Scan Tools A scan tool connects to the vehicle’s diagnostic link connector (DLC) (Figure 2-2). It communicates with the powertrain control module (PCM). While a scan tool cannot diagnose internal engine problems, it can give you information about engine performance issues. A scan tool can be very useful in diagnosing fuel and ignition system faults. Scan tools can be used on virtually any vehicle with a computer control system. Cars and light trucks that are of model year 1996 and newer are designated as OBD II (On Board Diagnostics) vehicles. These vehicles meet an EPA requirement for emissions and also have a standardized computer system and DLC. The DLC on an OBD II vehicle is found under the dash on the driver’s side (Figure 2-3). It is a 16-pin connector (Figure 2-4). You can find information about the location of the DLC in the service or owner’s manual. Some vehicles have the DLC hiding behind a cover on or near the dash.

43

A scan tool communicates with the powertrain control module to display diagnostic trouble codes and engine data. The diagnostic link connector (DLC) is a connector, usually located under the dash on an OBD II vehicle, which provides access to the PCM. The powertrain control module (PCM) is the vehicle’s computer that controls engine performance and related functions such as fuel and spark control. An OBD II (On Board Diagnostics) vehicle meets an EPA requirement for emissions and also has a standardized computer system and DLC location.

Figure 2-2  A scan tool communicates with the PCM and displays DTCs and engine data.

Pin 1

Pin 16

Figure 2-3  The DLC on an OBD II vehicle is located under the driver’s side dash.

Figure 2-4  An OBD II DLC.

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Chapter 2

Figure 2-5  Laptop computers are now often used as a scan tool.

An original equipment manufacturer (OEM) scan tool is vehicle brand-specific tool used by technicians at a dealership. The malfunction indicator light (MIL) is an amber light on the dash used to alert the driver of an emissions-related powertrain problem. A diagnostic trouble code (DTC) is a coded output from the PCM to identify system faults. A misfire is when a combustion event is incomplete or does not occur at all. A compression gauge is used to check the compression pressure of an engine cylinder. Pounds per square inch (psi) is a common measurement of pressure using the imperial standard system. The common measurement using the metric system is kilopascals (kPa).

Cars that are computer controlled and produced earlier than 1996 are labeled as OBD I. These cars are not standardized with their computer system and the location of the DLC. Different types of scan tools can be purchased to be used on OBD II-compliant vehicles. They fall into three main categories: global, enhanced, and OEM. A global OBD II scan tool will be able to connect and communicate with OBD II-compliant vehicles. Global OBD II scan tools can provide the technician with enough information to repair the most common emissions-related faults. Some manufacturers sell an enhanced OBD II scan tool, which can read more information from the vehicle’s computer. There is also a original equipment manufacturer (OEM) scan tool available for each vehicle. This scan tool will provide more data from the vehicle’s computer, which sometimes makes it easier to ­diagnose a problem. Many manufacturers are now using laptop and PC-based software to connect to the vehicle. The laptop then takes the place of a dedicated scan tool (Figure 2-5). Some manufacturers use a wireless connection to the vehicle. When the malfunction indicator light (MIL) is illuminated on an OBD II vehicle, it means that the PCM has stored a diagnostic trouble code (DTC). These alphanumeric codes can point you in the direction of a system fault. Connect the scan tool to the DLC, and follow the menu prompts to display DTCs or other engine-operating data such as engine coolant temperature, rpm, or vehicle speed. For example, if a DTC P0302 is found, it means that the PCM has detected a misfire on cylinder number two. It doesn’t tell you the cause of the misfire; that is still up to the technician to determine. You may have to perform a compression test to be sure that the valves and piston are sealing the cylinder properly.

Compression Testers Internal combustion engines depend on compression of the air-fuel mixture in the combustion chamber to maximize the power produced by the engine. The results of a compression test will help to determine how well a cylinder is sealing. A compression gauge is used to check cylinder compression. The dial face on the typical compression gauge indicates pressure in both pounds per square inch (psi) and metric kilopascals (kPa). The range is usually 0–300 psi and 0–2,100 kPa. Compression gauges can also have a digital readout. There are two basic types of compression gauges: the push-in gauge (Figure 2-6) and a screw-in gauge (Figure 2-7).

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

45

Compression gauge

Figure 2-6  Push-in compression gauge.

Figure 2-7  The more common screw-in style compression gauge.

A compression gauge that reads higher pressures and screws into the injector bore is used on diesel engines. Using a standard compression gauge on a diesel engine will damage the gauge.

Cylinder Leakage Tester If a compression test shows that any of the cylinders are leaking, a cylinder leakage test can be performed to measure the percentage of compression lost and help locate the source of leakage (Figure 2-8).

Vacuum Gauge

A cylinder leakage test is performed to measure the cylinder’s capability to seal (or percentage of leak).

Measuring intake manifold vacuum is another way to diagnose the condition of an engine. Manifold vacuum is tested with a vacuum gauge (Figure 2-9). Vacuum is formed on a piston’s intake stroke. As the piston moves down, it lowers the pressure of the air in the cylinder—if the cylinder is sealed. This lower cylinder pressure is called engine vacuum.

Figure 2-8  Typical cylinder leakage tester.

Figure 2-9  Vacuum gauge with line adapters.

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Chapter 2

If there is an intake vacuum leak, atmospheric pressure will force air into the cylinder, and the resultant pressure will not be as low. The reason atmospheric pressure will enter is simply that whenever there is both low and high pressure, the high pressure will always move toward the low pressure. The vacuum gauge measures the difference in pressure between intake manifold vacuum and atmospheric pressure. If the manifold pressure is lower than atmospheric pressure, a vacuum exists. Vacuum is measured in inches of mercury (in. Hg), kilopascals (kPa), or millimeters of mercury (mm Hg).

Vacuum Pumps There are many vacuum-operated devices and vacuum switches in cars. These devices use engine vacuum to cause a mechanical action or to switch something on or off. The tool used to test vacuum-actuated components is the vacuum pump. A handheld vacuum pump consists of a hand pump, a vacuum gauge, and a length of rubber hose used to attach the pump to the component being tested. Tests with the vacuum pump can usually be performed without removing the component from the car. While pulling a vacuum in a component, watch the action of the component. The vacuum level needed to actuate a given component should be compared to the specifications given in the factory service information. The vacuum pump is also commonly used to locate vacuum leaks. This is done by connecting the vacuum pump to a suspect vacuum hose or component and applying vacuum. If the needle on the vacuum gauge begins to drop after the vacuum is applied, a leak exists somewhere in the system.

Leak Detectors A vacuum or compression leak might be revealed by a compression check, a cylinder leak down test, or a manifold vacuum test; however, finding the location of the leak can often be very difficult. If visual inspection or listening for the hissing sound does not locate the source of a vacuum leak then other methods will need to be used. A simple but time-consuming way to find leaks in a vacuum system is to check each component and vacuum hose with a vacuum pump. Simply apply vacuum to the suspected area, and watch the gauge for any loss of vacuum. A good vacuum component will hold the vacuum that is applied to it. A smoke leak detector is an excellent tool to find vacuum and other leaks (Figure 2-10). The smoke leak detector uses shop air or bottled nitrogen and a nontoxic solution to blow low-pressure smoke through the system being tested. To test for vacuum leaks, use a plug (provided with the tool) to block off the throttle opening. Then connect the smoke line to a vacuum port, and activate the smoke tester. Smoke will stream out of any leaking area for easy detection. Follow the tool manufacturer’s guidelines for proper operation and applications. WARNING  When using a smoke leak detector to check for leaks on evaporative emissions systems, use nitrogen rather than shop air to pressurize the system to below 1 psi. Be sure to follow the manufacturers’ recommended procedures to ­prevent damage to the system or a hazardous situation for yourself and others.

Another method of leak detection is done by using an ultrasonic leak detector (Figure 2-11). Air rushing through a vacuum leak creates a high-frequency sound, higher than the range of human hearing. An ultrasonic leak detector is designed to hear the frequencies of the leak. When the tool is passed over a leak, the detector responds to the high-frequency sound by emitting a warning beep. Some detectors also have a series of light-emitting diodes (LEDs) that light up as the frequencies are received. The closer the detector is moved to the leak, the more LEDs light up or the faster the beeping occurs. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Figure 2-10  A smoke leak detector. 

Figure 2-11  An ultrasonic leak detector picks up the sound frequencies of the leak.

This allows the technician to zero in on the leak. An ultrasonic leak detector can sense leaks as small as 1/500 inch and accurately locate the leak to within 1/16 inch.

Cooling System Pressure Tester A cooling system pressure tester contains a hand pump and a pressure gauge (Figure 2-12). A hose is connected from the hand pump to a special adapter that fits on the radiator filler neck. This tester is used to pressurize the cooling system and check for coolant leaks. Additional adapters are available to connect the tester to the radiator cap. With the tester connected to the radiator cap, the pressure relief action of the cap may be checked.

Coolant Hydrometer A coolant hydrometer is used to check the amount of antifreeze in the coolant. This tester contains a pickup hose, coolant reservoir, and squeeze bulb. The pickup hose is placed in the radiator coolant. When the squeeze bulb is squeezed and released, coolant is drawn into the reservoir. As coolant enters the reservoir, a pivoted float moves upward with the coolant level. A pointer on the float indicates the freezing point of the coolant on a scale Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-12  A cooling system pressure tester.

Figure 2-13  Coolant hydrometer.

located on the reservoir housing (Figure 2-13). The reading must then be adjusted based on the temperature of the coolant. Some hydrometers have a built-in temperature gauge. There are separate readings (and sometimes separate hydrometers) for the different types of coolants.

Coolant Refractometer A coolant refractometer is an instrument that is used to determine the refractive index of the coolant sample that is placed on it. A refractometer works by having light pass through a slit. The light is refracted (bent) by the coolant sample. The index of refraction is the ratio of the speed of light in vacuum divided by the speed of light in the sample. The light is bent and put into two sample tubes, which are viewed in the eyeglass piece (Figure 2-14). This process will determine the specific gravity of the coolant solution; by understanding the specific gravity, we can understand the strength (percentage of the mixture) of the coolant and the freezing/boiling point. A refractometer is more accurate than a hydrometer because there is no temperature correction. A coolant refractometer can also be used with all major types of coolant.

Coolant Test Strips A coolant test strip is a piece of litmus paper that can test both the percentage of coolant and the acidity of the solution. This type of test is very important because if the antifreeze additives start to break down, corrosion and electrolysis will start to occur in the system. This type of information is good for the customer as well. If you can flush or replace the coolant before it does any major harm, you can save the customer a lot of money. This type of test is also easy to show the customer because it works well as a visual aid. A coolant test strip has separate color pads for the different types of coolants as well (Figure 2-15).

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Figure 2-14  Hold the refractometer up to your eye. Almost any light source will do.

Figure 2-15  You can test the coolant using a test strip.

Figure 2-16  This oil pressure gauge is threaded into the oil pressure sending unit’s bore.

Oil Pressure Gauge The oil pressure gauge may be connected to the engine to check the oil pressure (Figure 2-16). Various fittings are usually supplied with the oil pressure gauge to fit ­different openings in the lubrication system.

Belt Tension Gauge A belt tension gauge is used to measure timing or drive belt tension. The belt tension gauge is installed over the belt and indicates the amount of belt tension (Figure 2-17). A different type of tool called a cricket can be used to check a serpentine, micro-v, or v-belt’s tension (Figure 2-18).

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Figure 2-17  The belt tension gauge may be used to check or adjust timing belt tension.

Figure 2-18  The belt cricket can be used to check belt tension. There are different ones used for either ribbed or v-belts.

Modern drive belts are often made with EPDM (ethylene propylene diene monomer). To check a belt with EPDM, use the special tool (see Chapter 4, Figure 4-32) to check the depth of the belt. The tool will fit loose into the ribs of a worn belt and snug on a good one. Stretch belts are special belts that are self-tensioning. They are not universal replacement and are only used in some specific applications. Belt removal requires cutting the belt off. Special service tools are required for installation (Figure 2-19).

Stethoscope A stethoscope is used to locate the source of engine and other noises. Sound vibrations travel through the metal rod of the stethoscope, through the tube, and into the earpiece. The sound is then heard in both ears. The stethoscope pickup is placed on the suspected component, and the stethoscope receptacles are placed in the technician’s ears (Figure 2-20).

Figure 2-19  Installation Tool for Stretch Fit Belts.

Figure 2-20 Stethoscope.

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AUTHOR’S NOTE  For a long time as a technician, I used a long, skinny screwdriver to listen to abnormal engine noises. The screwdriver does work the same as the stethoscope, but it is not calibrated and designed to do so. After being introduced to using a stethoscope by a fellow technician, I discontinued my major use of the screwdriver for listening to engines. Having both earpieces is like having surround sound, and your senses are able to tune in better. It also silences the distracting noises that are around you, like an exhaust leak or a car in the next bay over.

Fuel-Pressure Gauge A fuel-pressure gauge (Figure 2-21) is used to measure the pressure in the fuel system. Fuel-injection systems rely on very high fuel pressures, from 35 psi to 70 psi. A drop in fuel pressure will reduce the amount of fuel delivered to the injectors and result in a lean air-fuel mixture. A fuel-pressure gauge is used to check the discharge pressure of fuel pumps, the regulated pressure of fuel-injection systems, and injector pressure drop. This test can identify faulty pumps, regulators, or injectors and can identify restrictions present in the fuel delivery system. Restrictions are typically caused by a dirty fuel filter, collapsed hoses, or damaged fuel lines. Some fuel-pressure gauges also have a valve and outlet hose for testing fuel pump discharge volume (Figure 2-22). The manufacturer’s specification for discharge volume will be given as a number of pints or liters of fuel that should be delivered in a certain number of seconds.

A fuel-pressure gauge is used to measure the pressure of the fuel system.

WARNING  While testing fuel pressure, be careful not to spill gasoline. Gasoline spills may cause explosions and fires, resulting in serious personal injury and property damage.

Figure 2-21  A fuel-pressure gauge. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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2 1 0 3 Fuel na 4 Cage

3 4

Figure 2-22  Checking fuel pump discharge volume.

Figure 2-23  A set of noid lights to fit a variety of connectors.

Noid Light Noid lights are used to check the electrical ­signal sent by the ­computer to the fuel injectors.

A special test light called a noid light can be used to determine if a fuel injector is receiving its proper voltage pulse from the computer. The wiring harness connector is disconnected from the injector, and the noid light is plugged into the connector (Figure 2-23). When the engine is turned over by the starter motor, the noid light will flash rapidly if the voltage signal is present. No flash usually indicates an open in the power feed or ground circuit to the injector. Noid lights may also be used in the connectors to many coil-on-plug ignition systems. Crank the engine over to see if the coil is receiving its voltage pulse from the PCM or ignition module.

EXHAUST GAS ANALYZERS An exhaust gas ­analyzer is a diagnostic tool that measures the amount and type of gas in the exhaust stream.

Exhaust gas analyzers are often called ­infrared testers. This is because many ­analyzers use infrared light to analyze the exhaust gases.

Exhaust gas analyzers are very valuable diagnostic tools. By looking at the quality of an engine’s exhaust, a technician can look at the effects of the combustion process. Any defect can cause a change in exhaust quality. The amount and type of change serves as the basis of diagnostic work. Modern exhaust gas analyzers are either four- or five-gas analyzers (Figure 2-24). A four-gas analyzer measures the level of hydrocarbons (HC) and carbon monoxide (CO) in the exhaust stream. These toxic pollutants are regulated by the EPA, and the level in the exhaust is measured in many states as part of an emissions inspection program. The four-gas analyzer also measures the level of oxygen (O 2 ) and carbon dioxide (CO 2 ). Seeing the level of these gases in the exhaust stream, in combination with the pollutants, can give an experienced technician a lot of information about the quality of combustion. If an engine is running too rich, the level of CO will be higher than normal and the oxygen will be lower. A few possible causes of a rich mixture are a faulty fuelpressure regulator or an oxygen sensor, a restricted exhaust, or low compression. An engine with an ignition misfire will emit high levels of unburned fuel in the form of hydrocarbons, and the oxygen level will also be high. Worn spark plugs or spark plug wires, or faulty coils are common culprits causing ignition misfire. A five-gas analyzer also measures the level of oxides of nitrogen (NO x ). This pollutant is formed when combustion temperatures are too high; it contributes to the formation of ground level ozone, smog.

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Engine Rebuilding Tools and Skills

Figure 2-24  A five-gas analyzer.

ENGINE ANALYZER During a complete engine performance analysis, an engine analyzer may be used. An engine analyzer houses much of the necessary test equipment. Although the term engine analyzer is often loosely applied to any multipurpose test meter, a complete engine analyzer will incorporate most, if not all, of the test instruments mentioned in this chapter. Most engine analyzers are based on a computer that guides a technician through the tests. Most will also do the work of the following tools: ■■ Compression gauge ■■ Pressure gauge ■■ Vacuum gauge ■■ Vacuum pump ■■ Tachometer ■■ Timing light/probe ■■ Voltmeter ■■ Ohmmeter ■■ Ammeter ■■ Oscilloscope ■■ Computer scan tool ■■ Emissions analyzer With an engine analyzer, you can perform tests on the battery, starting system, ­charging system, primary and secondary ignition circuits, electronic control systems, fuel system, emissions system, and the engine assembly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Modern engine analyzers have Internet connections that allow the technician to share the information and data with a technical support team that is off-site.

ENGINE MEASURING TOOLS Proper operation of the engine requires that most internal components be manufactured with very precise tolerances. To measure these components properly, special micrometers capable of determining ten-thousandths (0.0001) of an inch or one-thousandth (0.001) of a millimeter are used. WARNING  Measuring tools require special care. They are delicate instruments and cannot withstand abuse. Handle them with care to prevent dropping, striking, or other abusive actions.

Some components of the engine have wider tolerance ranges, and measurements are not as critical. In these areas, less delicate tools may be used; however, accuracy is not as precise. Tools used for these areas include feeler gauges, machinist’s rule, calipers, micrometers, and dial indicators. Today, most measurement specifications are stated using the metric system. It is best to have the proper tools to measure in the system stated by the specifications. However, it can get expensive having to purchase duplicate tools. Specifications and measurement readings can be converted between the two systems, allowing the use of one set of tools (Figure 2-25).

Feeler Gauges A feeler gauge is a thin metallic strip of a known thickness.

A feeler gauge can be used to measure valve clearance, crankshaft end play, connecting rod side clearance, piston ring side clearance, and other measurements when exacting measurements are not critical (Figure 2-26). The thickness of the gauge is stamped on the blades in thousandths of an inch or tenths of a millimeter. To Find

Multiply

3

Conversion Factors 25.40

millimeters

5

inches

3

centimeters

5

inches

3

centimeters

5

feet

3

meters

5

feet

3

0.3281

kilometer

5

feet

3

0.0003281

kilometer

5

miles

3

1.609

inches

5

millimeters

3

0.03937

inches

5

centimeters

3

0.3937

feet

5

centimeters

3

feet

5

meters

3

feet

5

kilometers

3

yards

5

meters

3

1.094

miles

5

kilometers

3

0.6214

2.540 32.81

30.48 0.3048 3048

Figure 2-25  Common English/metric conversion factors. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-26  Feeler gauge set used to measure clearances.

The most common style of feeler gauge is the blade type. This gauge is constructed of metal strips approximately 12 millimeters wide. Several different types of feeler gauges are available to perform some specific functions.

Using Feeler Gauges Proper use of a feeler gauge requires the technician to develop a feel for the drag on the gauge when it is removed from the gap. To measure gap width, start with a gauge thinner than the gap and continue to increase the gauge size. The measurement of the clearance is the blade that has a slight drag when it is moved in and out. The size can be confirmed by selecting the next size gauge and attempting to slide it into the gap; it should not fit. Feeler gauges are also used when adjusting clearances, such as valve lash. In this instance, use the gauge the same size as specified in the service information. With the lock nut on the rocker arm backed off, adjust the lash until you feel a slight drag as you move the feeler gauge back and forth. Tighten the lock nut, being careful not to change the gap.

Machinist’s Rule The machinist’s rule usually contains four different scales, two on each side of the rule. Common English scales include 1/8, 1/16, 1/32, and 1/64 inch (Figure 2-27). A decimal machinist’s rule is also available with the scales divided into decimal intervals of 0.1, 0.02, and 0.01. Common scales on metric rules are divided into centimeters and millimeters.

The machinist’s rule is used to measure distances or components that do not require ­precise measurement. It is similar to a ruler with multiple scales. A scale is the distance of the marks from each other.

Calipers Calipers are used to take inside, outside, and depth measurements not requiring accuracy to a thousandth of an inch (Figure 2-28). Typical usages include measuring valve springs, piston diameters, and bearing thicknesses. A graduated steel beam contains a fixed jaw with a sliding scale. There are two types of calipers available for use in automotive repair: vernier and dial. Either one may be capable of displaying both English and metric measurements. Vernier Calipers.  The vernier caliper is a basic measuring instrument. The base (bar) scale on the beam is divided into 10 equal parts. Each part is equal to one-tenth (0.1) of an inch. Small numbers from 1 to 9 appear between each inch. These numbers have a value of hundred-thousandths (0.100) of an inch. Between each of these numbers are four graduations or marks. Since each number is equal to 0.100 inch, the value of these small

A caliper is a precision measuring tool that is used to measure the inside, outside, and depth of an object. Vernier calipers use a vernier scale, allowing for measuring to a precision of 10 to 25 times as fine as the base scale.

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Chapter 2 1 -inch 8

scale

5

6

1

1 -inch 32

scale

scale

28

24

20

16

12

8

4

8

16

24

32

40

48

56

4

1 -inch 16

2

5 1 16

24

32

40

48

56

2

1 -inch 64

scale

Figure 2-27  Typical scales used on a machinist’s rule.

Measuring the internal diameter of tubing Cutaway internal view

90

0

Measuring depth of a base

10 20

80 70

30

60

50

40

Measuring the outside diameter of round stock

Figure 2-28  Dial calipers can be used to measure many different parts.

Special Tools Vernier calipers

graduations is 25 thousandths (0.025) of an inch. The vernier scale is divided into 0.001-inch increments with 25 graduations. The scale is marked with the numbers 5, 10, 15, 20, and 25. These numbers represent values of 0.005, 0.010, 0.015, 0.020, and 0.025 inch, respectively. Metric calipers have a base scale in millimeters, with the vernier scale divided into 0.02 mm. Both calipers work identically. The end jaw is fixed to the scale, while the other slides on it. The piece being measured is located between the jaws. A thumb screw moves the adjustable jaw. The length of the scale determines the size of the calipers. The most common are 6 and 12 inches. Measurements are obtained using a combination of the base scale and the vernier scale. To read a vernier caliper, the zero on the left edge of the vernier scale shows the base measurement. If the zero aligns with an increment mark of the beam, the last digit of the

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Engine Rebuilding Tools and Skills 0

1

0

2

3

5

0.075"

4

10

5

15

6

20

7

57

8

25

0.075" Main scale 0.000" Vernier scale 0.075" Total

Figure 2-29  If the zero aligns with a base scale graduation, the vernier scale is not used. In this case, the reading is 0.075 inch.

0

1

0

2

3

5

4

10

5

15

6

20

7

8

25

0.105" 0.100" Main scale 0.005" Vernier scale 0.105" Total

Figure 2-30  Since the zero does not align with a base scale graduation, the vernier scale is used. In this case, the reading is 0.105 in. since the 5 is aligned.

measurement is zero (Figure 2-29). If the zero is not aligned with any marks, look down the vernier scale to find the number that aligns perfectly with any line on the main scale. Use the vernier scale to determine the value to be added to the base measurement. There will always be one set of lines that will align with each other (Figure 2-30). For example, if the measured component were 0.034 inch, then the caliper scales would be read as follows: Base measurement—0.025 inch Vernier scale—0.009 inch Total measurement—0.034 inch Dial Calipers.  Some calipers are fitted with a dial to make measurement reading easier. To measure a component, use the thumb wheel to open the jaws, and then close the jaws over the component. The dial uses a rack and pinion mechanism to transfer movement of the jaws to the dial needle. Like the vernier caliper, the base measurement is taken from the beam, and the dial reading is added to it. The base scale on an English dial caliper is marked in 0.100-inch increments, and the dial provides the thousandths (0.001) of an inch readings. Most metric calipers have base scale increments of 2 mm and dial increments of 0.01 mm. Follow the steps in Photo Sequence 3 to accurately measure a component using an English system dial caliper.

Dial calipers are similar to vernier calipers, except the dial performs the function of the ­vernier scale.

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PHOTO SEQUENCE 3

Typical Procedure for Reading a Dial Caliper

P3-1  Once you have taken your measurement, lock it in place and remove it from the part. This makes reading the measurement easier.

P3-2  The dial caliper being used in this example has a range from 0 to 6 inches. Each division between the inches is one-tenth of an inch (0.1 in.).

P3-3  Set the dial caliper in your right hand so that the gauge can be easily read and your thumb is on the wheel.

P3-4  Make sure that you are using the beveled edge of the caliper jaws as the contact point.

P3-5  Make sure the jaws are clean and close them all the way. Zero the gauge if needed.

P3-6  Using your thumb to slide the jaws of the caliper, move it into the approximate desired measuring position.

P3-7  View and record the measurement on the sliding ruler. In this example, the caliper reads 0.4 in.

P3-8  After reading the inches and first decimal place, you can read the dial. In this example, each mark on the dial measures one-­thousandth of an inch (0.001 in.). This will give you the second and third decimal places. In this example, the dial reads 55. That means that 0.055 in. is added to the first number.

P3-9  The total measurement is the sum of all the recorded numbers.

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59

IN

Outside measurement

Figure 2-31  Electronic digital caliper makes quick work of measuring.

The latest innovation in calipers provides a digital readout. An internal microprocessor calculates the position of the jaws and shows the reading in a display window (Figure 2-31). Some electronic digital calipers have data ports to log readings on a computer.

Micrometers A micrometer is used to make precise measurements (Figure 2-32). Most micrometers will measure to 0.001 inch, or 0.01 mm. However, to perform some measurements in engine applications, a micrometer capable of measuring within 0.0001 inch or 0.001 mm may be required. The micrometer has a range it will work within (Figure 2-33). Unlike calipers, different micrometers are used to take outside, inside, and depth measurements. The principle of the micrometer is to record the advancement of a screw for a number of turns or parts of a turn. The major components of a micrometer include the following (Figure 2-34): ■■ Frame ■■ Anvil ■■ Spindle

A micrometer may be called a “mike.” A micrometer is a ­precision measuring tool; some can measure to 0.0001 inch and measure the outside or inside diameter or depth of an object.

Figure 2-32  You will use a 0–1-inch micrometer to measure many engine components. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-33  A set of micrometers with a range of up to 4 inches. Measuring faces Anvil

Spindle

Sleeve

Thimble

Frame

Figure 2-34  Parts of an outside micrometer.

Figure 2-35  The sleeve is usually marked in 0.025-inch increments. To read the sleeve, count the visible lines by 0.025.

Lock Sleeve ■■ Sleeve reading line ■■ Thimble English system micrometers have marks on the sleeve in 0.025-inch increments (Figure 2-35). The marks on the thimble are in 0.001-inch increments. One complete revolution of the thimble equals 0.025-inch movement of the spindle. If the micrometer is capable of measuring to the ten-thousandths of an inch, a vernier scale is also on the sleeve (Figure 2-36). Metric micrometers mark the sleeve in 0.5-mm increments and the thimble scale in 0.01-mm increments. ■■ ■■

Reading a Micrometer Every time a micrometer is used, its calibration should be checked and if needed, adjusted. Calibration is checked by cleaning the faces of the anvil and spindle, and then closing them (on 0- to 1-inch micrometers). The scale should indicate a zero reading. Micrometers Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Gauge standard

Figure 2-36  A micrometer with a 0.0001-inch scale on the upper left of the sleeve. Figure 2-37  A standard test gauge is used to calibrate outside micrometers over 1 inch.

greater than a 1-inch range will require that a standard test gauge be placed between the anvil and spindle (Figure 2-37). When the faces are closed against the standard, the scale should read zero. If adjustments are necessary, perform the following procedure on a typical micrometer:

1. Clean both faces of the spindle and anvil. 2. Close the faces together or against the appropriate standard gauge. 3. Remove the knurled cap on the end of the thimble and loosen the set screw. 4. Make the zero line on the thimble coincide with the zero line on the barrel. 5. Lightly tighten the set screw. 6. Separate the faces by turning the spindle. 7. Hold the micrometer by the thimble and securely tighten the set screw. 8. Recheck zero calibration again. 9. Replace the thimble cap.

Reading inside or outside micrometers is done using the same procedures. Follow the steps in Photo Sequence 4 to accurately measure a component using an English system micrometer. Before making any measurements, clean the part and the micrometer. When taking the measurements, the anvil and spindle must be at right angles to the part being measured. To ensure proper contact, slightly rock the micrometer as the spindle is turned. Do not overtighten the spindle. The spindle and anvil should just come into contact with the part so a slight drag is felt when the micrometer is removed. On many micrometers, the end has a slip (clutch) gauge. If you tighten the micrometer by the end of the thimble, it will stop rotating when a set resistance is reached. As with the caliper, measurement readings are obtained by adding the markings together. Begin by finding the largest number shown on the sleeve. If no other marks on the sleeve are visible and the zero on the thimble aligns with the reading line, the sleeve shows the size of the component (Figure 2-38). Any marks that are visible after the number on the sleeve are added to the number (Figure 2-39). If the zero on the thimble scale does not align with the reading line, add the value to the thimble reading (Figure 2-40). Some micrometers are capable of reading ten-thousandths (0.0001) of an inch. The vernier scale is used if no lines on the thimble align with the reading line. To read the vernier scale, find the line on the vernier scale that aligns with a line on the thimble scale. Add the number from the vernier scale to the sleeve and thimble readings (Figure 2-41). Setting up the metric micrometer is the same. Each number on the sleeve represents 5 mm, with graduations of 0.5 mm between them. The thimble is divided into 50 equal divisions, each being 0.01 mm. The reading obtained on the thimble is

Special Tools Micrometer set

Outside micrometers are designed to ­measure the outside diameter or thickness of a component. Inside micrometers are used to measure the inside diameter of a hole. Depth micrometers are used to measure the depth of a bore.

Special Tools Metric micrometer set

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Figure 2-38  Since the zero on the thimble scale aligns on the reading line and the last sleeve graduation is 5, the reading is 0.500 inch.

Figure 2-39  If the graduation marks are visible after a number on the sleeve scale, add the graduation value to the number. In this case, the micrometer reads 0.375 inch.

765 4 3 2 1

18 17 16

15

14 13 12 11 9 10 8

Figure 2-41  Some micrometers have vernier scales that allow readings to a ten-thousandths of an inch. The 2 on the vernier scale is the only one that aligns with a thimble graduation mark. The reading is 0.3112 inch.

Figure 2-40  Use the thimble scale to determine the thousandths to be added to the sleeve scale. This micrometer is reading 0.3112 inch.

0

5

30

25

0

5

30

Sleeve

Thimble 25

Reading 5.78 mm

Figure 2-42  Reading a metric micrometer is much like reading a standard micrometer. This scale indicates 5.78 mm.

added to the reading on the sleeve (Figure 2-42). In this example, the sleeve reading is 5.5 mm, and the thimble reading is 0.28 mm. The total reading is obtained by adding the sleeve reading to the thimble reading; in this case, the total is 5.78 mm. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 4

Typical Procedure for Reading a Micrometer

P4-1  Tools required to perform this task are a micrometer set and a clean shop towel.

P4-2  Select the correct micrometer. If the component measurement is less than 1 inch, use the 0- to 1-inch micrometer.

P4-4  Locate the component between the anvil and spindle of the micrometer, and rotate the thimble to slowly close the micrometer around the component. Tighten the thimble until a slight drag is felt when passing the component in and out of the micrometer. If the micrometer is equipped with a ratchet, it can be used to assist in maintaining proper tension.

P4-7  Each number on the sleeve is 0.100 inch, and each graduation represents 0.025 inch. To read a measurement, count the visible lines on the sleeve.

P4-5  Lock the spindle to prevent the reading from changing.

P4-8  The graduations on the thimble define the area between the lines on the sleeve in 0.001 increments. To read this measurement, use the graduation mark that aligns with the horizontal line on the sleeve.

P4-3  Check the calibration of the micrometer.

P4-6  Remove the micrometer from the component.

P4-9  Add the reading obtained from the thimble to the reading on the sleeve to get the total measurement.

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Chapter 2 Outside micrometer Telescoping gauge

Figure 2-43  Telescoping gauges are used to measure inside bore diameters.

Figure 2-44  To determine the diameter of the bore, use an outside micrometer to read the width of the gauge.

Telescoping Gauge Telescoping gauges are used to measure the inside diameter of a hole. They are sometimes called snap gauges.

Telescoping gauges are used to measure the inside diameters of bores (Figure 2-43). The plungers are retracted and locked with the lock screw. The gauge is then inserted into the bore. When the lock screw is loosened, the plungers extend under spring pressure. Lock the lock screw, and then rock the gauge to ensure it is at the largest diameter. If any corrections must be made, loosen the lock screw and repeat. With the gauge removed from the bore, the plunger distance is measured with an outside micrometer (Figure 2-44).

Small-Hole Gauge A small-hole gauge consists of a round head, wedge, and a lock handle (Figure 2-45). The round head is inserted into the bore, and the handle is rotated to expand the head outward. When the split ball contacts the bore walls, the gauge is removed. An outside micrometer is used to measure the diameter of the head.

A small-hole gauge is used to measure smaller holes or bores than a telescoping gauge can measure. The dial indicator ­measures the travel of a plunger in contact with a moving component.

Dial Indicators Dial indicators can be used to measure valve lift, shaft out-of-round, and end play (Figure 2-46). The dial indicator consists of a dial face with a needle. The dial is usually calibrated in 0.001-inch increments. Most metric system dial indicators measure

Attachment Pry bar

Dial indicator

Crankshaft

Figure 2-45  A small-hole gauge set.

Figure 2-46  A dial indicator can be used for several measurements, including crankshaft end play.

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in 0.01-mm increments. A spring-loaded plunger or toggle lever transfers movement to the dial needle. To achieve accurate readings, the plunger must be preloaded.

Using a Dial Indicator To use the dial indicator, attach it to its stand. The stand is attached to the indicator by a lug on the back of the housing. Stands can be clamp type (using a small C-clamp) or permanent magnet type. It is important to ensure a rigid mounting of the dial indicator stand to achieve accurate measurements. Adjust the stand until the dial indicator plunger contacts the piece being measured. Try to set the support arms as short as possible to keep the setup rigid. Mount the indicator so the plunger is at a 90-degree angle with the part. If the plunger is mounted at an angle, an accurate reading will not be obtained. In addition, to obtain accurate readings, preload the plunger until about one-half of the plunger is outside of the indicator. If the dial is equipped with a movable face, adjust it so the needle is pointing to zero (Figure 2-47). Movement of the workpiece will be measured on the dial (Figure 2-48). Look at the dial straight on; looking from at an angle will give false readings. If the needle travels completely around the dial, add that value to your final reading to get the total measurement. When reading runout measurements, the needle may move in both directions from zero. The total indicated reading (TIR) is the amount of movement on both sides of zero added together; for example, if the needle indicates movement of 0.015 inch (0.40 mm) on one side of zero and 0.025 inch (0.65 mm) on the other side, the TIR is 0.040 inch (1.0 mm).

Valve Guide Bore Gauge Valve guide bore can be measured using a small-hole gauge; however, valve guide bore gauges are available for quick, accurate measurements. The slim probe is inserted into the guide, and the bore diameter is displayed by the dial indicator. Moving the gauge up and down the bore provides taper measurements, while rotating the gauge provides outof-round measurements.

Valve Seat Runout Gauge A valve seat runout gauge consists of a dial indicator, an arbor, and an indicator bar. The arbor centers the tool into the valve guide, and the indicator bar rests on the valve seat. The tool is rotated while observing the dial indicator.

Cylinder Bore Dial Gauge Cylinder bore taper and out-of-round can be measured using an inside micrometer or telescoping gauge. For faster measurements of the cylinder, most high-volume shops use a cylinder bore dial gauge (Figure 2-49). This gauge can quickly provide cylinder bore

Figure 2-47  Rotate the face of the dial to align the pointer on zero.

Special Tools Dial indicator

The valve guide bore gauge provides a quick measurement of the valve guide. It can also be used to measure taper and out-of-round. The valve seat runout gauge provides a quick measurement of the valve seat concentricity. A cylinder bore dial gauge is a special type of dial gauge that fits in a common engine cylinder. The dial reads similar to other dial gauges.

Figure 2-48  The pointer will indicate the amount of movement of the plunger.

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Figure 2-49  A common type of cylinder bore dial gauge.

Special Tools Cylinder bore dial gauge Setting fixture

diameter, taper, and out-of-round. Most rocking type gauges consist of a handle, guide blocks, lock, indicator contact, and dial indicator. To make the gauge universal, extensions can be added to the indicator contacts. The sliding guides center the plunger in the bore. While slightly rocking the gauge up and down in the bore, observe the smallest reading obtained (pointer reverses direction). This is the diameter of the bore. Another type of bore gauge is the sled type. When it is inserted into the bore, the plunger spring pushes the sled against the cylinder wall. After the dial is set to zero, slide the gauge up and down and rotate it around the bore. This will provide taper and out-ofround measurements. As a cylinder wears, it becomes out-of-round and tapered. Out-of-round is caused by the thrusts applied to the piston, forcing it into the cylinder wall. Taper occurs as the rings travel against the cylinder wall. If the cylinder is worn excessively, it may require cylinder boring. To measure the amount of cylinder out-of-round, measure the bore in three directions at the same bore depth (Figure 2-50). Subtracting the smallest reading from the largest provides the amount of cylinder out-of-round. Taper is measured by comparing the readings obtained at the top of the ring travel with the reading at the bottom of the ring travel. The difference between the two readings is the amount of cylinder taper. Bore gauges do not read the actual size of the bore; instead they must be set up for a specified size, and the dial will indicate the amount of deviation from this size. To use a cylinder bore dial gauge, first obtain the bore size specifications in the service information. Adjust the gauge setting fixture to the specified size by placing the correct size spacer bar for the inch increments. Use the micrometer to set the fractions of an inch. Once the setting fixture is set up, the bore gauge is ready to be set. Begin by placing the gauge in the setting fixture and attaching the correct size extension. The extension must push the plungers on the gauge back into the base. Set the dial to zero by turning the extension in and out. Lock the dial at zero by tightening the lock nut on the extension. Fine tune the zero adjustment by rotating the dial faceplate, using the serrated rim. This sets the gauge to read zero at the specified size of the bore. Insert the gauge into the bore, and measure the diameter.

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RIGHT

FRONT

REAR

DIAGONAL LEFT THE DIFFERENCE BETWEEN THE LARGEST AND SMALLEST DIAMETERS EQUALS OUT-OF-ROUND.

Figure 2-50  A cylinder bore does not wear round. To measure the amount of out-of-round, measure in three directions toward the top of the cylinder.

Out-of-Round Gauge Engine bearings will conform to the shape of the main bore. For this reason, the bore must be perfectly round. This measurement can be made using an inside micrometer; however, a special out-of-round gauge provides quicker measurements. The out-of-round gauge consists of a base with a dial indicator (Figure 2-51). An adjustable slide is located on the bottom of the base. To use, set the locking slides to the diameter of the bore, and set the dial indicator to zero. Next, rotate the gauge in the bore. The dial indicator will provide a plus or minus reading, indicating any variance in the bore diameter.

Out-of-round gauges are used to measure the concentricity of connecting rod and main bores.

Aligning Bar Alignment of the crankshaft bores must be checked to determine warpage. A straightedge and feeler gauge set can be used to measure warpage. Another method is to use an ­aligning bar. With all main bearings removed from the crankshaft bores, the correct size aligning bar is placed onto the bearing saddles. Next, the bearing caps are installed and torqued to specifications. If the bar can be rotated with the use of a 12-inch lever, the saddle bores are aligned. If there is a variation in saddle placement, the bar will not rotate.

Aligning bars are used to determine the proper alignment of the crankshaft saddle bores.

Figure 2-51  An out-of-round gauge checks connecting rod bores quickly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-52  Plastigage is the small plastic strip inside the envelope. The outside of the envelope has the measuring scale on it. Check width of plastigage Place plastigage full width of journal about 1/4” off center

0.002” clearance

32 1.5 1

32 1.5 1

32 1.5 1

Installing plastigage

Measuring plastigage

Figure 2-53  A piece of plastigage is laid across the crankshaft journal.

Figure 2-54  Use the scale on the wrapper to compare the width of the plastigage.

Plastigage Plastigage is a plastic thread used to measure the clearance between two components.

Plastigage (Figure 2-52) is commonly used to measure the oil clearance between the main bearings and the crankshaft, and between the crankshaft and the connecting rod bearings. The plastigage is placed on the crankshaft prior to installing the bearing half and cap (Figure 2-53). The bearing half and cap are installed, and the fasteners are torqued to the proper specifications. The clamping force causes the plastigage to flatten. The amount of flattening depends on the oil clearance. The bearing half and cap are then removed, and the thickness of the plastigage is measured using the scale provided on the package (Figure 2-54). A metric scale is provided on one side of the package, while an English scale is on the reverse side. Plastigage is available in different diameters for measuring a variety of clearances.

SPECIAL HAND TOOLS A few special hand tools are designed to make the operation of engine rebuilding or repairing easier. Although most of these are optional, some are essential to perform an engine repair correctly. These include torque wrenches and torque angle gauges.

Torque Wrenches Most of the fasteners used to attach components to the engine block require proper torquing; for example, the cylinder head must be properly torqued to set the bolts and apply the correct amount of pressure to seal the combustion chamber and water passages. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-55  Different styles of torque wrenches: (l–r) beam type, click type, and dial indicator type.

In addition, proper torquing sets the stress into the block. If the bolts were not torqued properly, the cylinder head or block could warp. One of the most important tools used during an engine service, reconditioning, or rebuild is the torque wrench. Never guess at a torque value. The torque wrench will give you a precise indication of the torque being applied either by a click, a light, a beam, or a dial (Figure 2-55).

Using a Torque Wrench Many different types of torque wrenches are available. Since each type is used differently, always refer to the manufacturer’s instructions when using a torque wrench. There will be times when an adapter is required to gain access to a fastener. Some adapters will affect the reading obtained by the torque wrench. If an adapter that increases the length of the torque wrench between the fastener and handle is required, the reading must be corrected. This is required since a longer bar changes the leverage applied to the fastener. Torque wrenches are calibrated for the length they are designed. Use the following formula to correct the reading if an adapter is required: Wrench reading 5

Special Tools Torque wrench A torque wrench is a precision measuring tool that is used to connect to a socket and provide a measurement of fastener torque.

Extensions that increase the height of the wrench from the fastener will not affect the torque reading, provided they do not twist.

Torque at fastener 3 Wrench length Wrench length 1 Adapter length

For example, if the torque specification is 50 foot-pounds, and a 6-inch extension is installed onto a 16-inch wrench, the calculated reading on the wrench would be 36 foot-pounds. At 36 foot-pounds, the actual applied torque to the fastener is 50 footpounds. So fasteners require the use of lubricating oil while some only need clean dry threads. Lubricating a bolt that is supposed to be installed dry will cause it to be over torqued and may even cause it to break. Check the service information for recommendations. A torque angle gauge is not like a torque wrench; it does not measure torque. It is a gauge that measures the amount of circular movement (in degrees) as you tighten down a fastener with a ratchet or breaker bar (Figure 2-56). Most torque angle gauges have a square fitting for a 1/2-in. or 3/8-in. ratchet and a similar-sized socket fitting on the other end. A torque angle gauge is used when you are tightening torque-to-yield bolts. Cylinder head bolts are one example of where torque-to-yield bolts might be used.

Special Tools Torque angle gauge

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Figure 2-56  The torque angle has a clamp to hold it still while turning the ratchet.

Torque-to-Yield A bolt that has been torqued to its yield point can be rotated an additional amount without any increase in clamping force. When a set of torque-to-yield fasteners is used, the torque is actually set to a point above the yield point of the bolt. This ensures that the set of fasteners will have an even ­clamping force.

Torque-to-yield bolts must be tightened using the procedure specified by the vehicle manufacturer. A typical method is to tighten the bolts in two steps: 1. Tighten to the specified torque value. 2. Tighten the fastener an additional amount as stated in the specifications. Torquing to the specifications may require more than one step. The first step may be about one-half the total specification, with the final torque being obtained in additional steps. The fastener is then stretched by turning it an additional amount. You should not guess, or estimate by using your eye, how much angle your ratchet has turned. To accurately measure the amount of additional angle being applied, a torque angle gauge should be used (Figure 2-57). Attach the gauge to the wrench, and secure the rod against a surface. Turning the wrench will result in the needle indicating the amount of rotation. WARNING In general, do not reuse torque-to-yield bolts; they have been stretched during installation. Some manufacturers allow their torque-to-yield bolts to be reused two times. As always, check the manufacturer’s service ­information to perform the procedure correctly.

Torque wrench

Torque angle gauge

Figure 2-57  Many engines use torque-to-yield ­fasteners that require a torque angle gauge to tighten properly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-58  Ring expanders help in removal and installation of the rings.

Ring Expanders To prevent damage to the rings during disassembly and assembly, a special ring expander can be used (Figure 2-58). The ring expander will safely expand the rings wide enough to allow them to be slipped out of the groove and over the piston dome.

Ring-Groove Cleaners Before installing rings onto the piston, it is important to remove any carbon or other contamination from the ring groove. A ring-groove cleaner provides a fast method of thoroughly cleaning the grooves (Figure 2-59). If a ring-groove cleaner is not available, break an old ring and use the sharp edge to clean inside the groove. Do not use enough force to scratch the piston surfaces.

Ring Compressors To prevent ring or piston damage during installation of the piston assembly into the block, the rings must be compressed to a size smaller than the cylinder bore. Several different types of ring compressors are available to perform this task (Figure 2-60).

Figure 2-59  The safest way to clean piston ring grooves is with a special-groove cleaner.

Figure 2-60  A common ring compressor.

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ENGINE AND CHASSIS DYNAMOMETERS

An engine dynamometer is a machine bolted to the engine and used to measure the torque of the engine when it is running.

Often after an engine is rebuilt, it is tested. If the engine is remanufactured at a facility, it is tested on an engine dynamometer. If an engine is rebuilt at a local or smaller facility, it is often tested after it has been installed in the vehicle. An engine dynamometer is a machine that is bolted up to the crankshaft of the engine to measure its horsepower and torque. The engine dynamometer takes the place of and bolts to where the transmission would be. This means that the dynamometer will measure the power of the engine only and will not measure the power losses of the transmission and drivetrain. The operator must control both the engine and the dynamometer. The dynamometer creates a resistance to the engine and makes the engine work harder. The operator will then increase the speed of the engine to overcome the resistance of the dynamometer. The engine then builds up speed, and its maximum torque can be measured. Horsepower is not actually measured; rather, it is calculated by measuring the torque and the speed of the engine in rpm. Horsepower is then calculated as torque times engine speed divided by 5,252: Horsepower 5

Torque 3 Engine rpm 5,252

The most common types of dynamometers used are the water brake type, electric eddy current, and hydraulic. Each type of dynamometer has an advantage or disadvantage to the user. Many factors go into the decision to purchase a dynamometer, such as cost, maintenance, accuracy, and repeatability. It is common for a high-performance engine or machine shop to have an engine dynamometer. They will use it to test the engine after a rebuild, but they will also use it to fine-tune and modify the engine and its control system for maximum power. A chassis dynamometer is used for similar purposes of testing and tuning an engine. The only difference is that the engine is installed in the vehicle and the power is measured at the tires. The chassis dynamometer has a rolling drum that the tires drive on. The drum then rotates with resistance that is controlled by the operator. The types of chassis dynamometers are the same as described earlier.

SPECIAL RECONDITIONING TOOLS AND EQUIPMENT Caution Do not attempt to remove a valve spring keeper without first filling the cylinder with compressed air. Doing so will allow the valve to fall into the cylinder and require head removal to retrieve it. Also, disconnect the battery before filling the cylinder with compressed air. The engine may rotate, and if the ignition is in the RUN position, the engine may start.

Various special tools and equipment are used in rebuilding and reconditioning automotive engines. Some equipment is used by specialty machine shops, while other equipment is found in most automotive repair facilities. This portion of the chapter discusses the basics of most of these types of equipment. Even though you may not operate the equipment, it is important to understand what is being performed and what can be done to correct a defective component.

Cylinder Head Reconditioning Equipment Cylinder heads contain areas that are subject to wear and damage due to the immense pressures and temperatures that they are exposed to. Many types of tools and equipment are available to recondition the cylinder head, including the following: ■■ Valve spring compressor ■■ Valve spring tension tester ■■ Valve guide renewing equipment ■■ Seat grinder ■■ Seat cutter ■■ Seat inserters ■■ Valve grinding equipment ■■ Head resurfacing equipment

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Engine Rebuilding Tools and Skills

Valve Spring Compressor.  To remove the valve springs, they must first be compressed so the keepers can be removed. Many types of spring compressors are available. Some are designed to allow valve spring removal without first removing the cylinder head from the block. Other designs are used only with the cylinder head removed from the engine. In addition, there are special spring compressors used for Over Head Camshaft (OHC) engines. A pry-type spring compressor is one design that provides valve spring removal with the cylinder head attached to the block (Figure 2-61). With the piston at TDC, the cylinder is filled with compressed air to hold the valve in place and prevent it from falling into the cylinder. The hole in the pry bar fits over the rocker arm stud and provides a pivot point to compress the spring. OHC engines may require a special type of spring compressor (Figure 2-62). This style can usually be used with the head installed or removed from the engine block. This type bolts to the cylinder head and uses adapters attached to a threaded extension. Turning the T-handle forces the adapter down onto the spring and compresses it. Another version uses a pry-bar-type handle to apply the pressure. A C-clamp-type compressor is used to remove the valve springs with the cylinder head removed (Figure 2-63). WARNING  Always wear eye protection whenever using a valve spring c­ ompressor. It is possible for something to slip or come loose, resulting in airborne parts.

Valve Spring Tension Testers.  Before valve springs are used, they must be tested to determine if they are within the manufacturer’s specifications for tension. Specifications are usually supplied for open and closed spring tensions. Two types of tension testers are used to make these measurements. The first uses a needle indicating torque wrench (Figure 2-64). The adjusting wheel is used to set spring height, and pressure is applied to the torque wrench until a click is heard. At this point, the value on the torque wrench is read and the reading is multiplied by two. This measurement should be within 10 percent of the valve closed specification.

73

Valve spring tension testers are used to measure the open and closed valve spring ­pressures. Proper closed pressure is required for a tight seal. Proper open pressure overcomes the effects of inertia and ensures proper valve closing.

Installed height is sometimes referred to as closed height.

Remove rocker arm

Compress the spring with a special tool or pry bar

Figure 2-61  Compressing valve springs using a pry-bar-type compressor. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Valve spring compressor

Figure 2-62  Some overhead camshaft engines require a special type of valve spring compressor. This type can be used with the cylinder head installed or removed from the block.

Figure 2-63  A C-clamp-type spring compressor is used when the cylinder head is removed from the engine. This compressor is air operated; others may be hand operated.

Figure 2-64  This style of valve spring tension tester uses a torque wrench to determine tension at the specified height.

Caution

Figure 2-65  A dial type spring tension gauge.

For proper spring ­tension measurements to be obtained, the spring tension must be checked at the installed spring height. If a shim is used, it must be inserted under the spring ­during this check. Knurling a valve guide cuts and deforms the metal to straighten it out.

The second type of tester uses a scale with a dial reading (Figure 2-65). Pressure is applied against the spring until it is compressed to the spring installation height specification. A scale on the right of the tester is used to indicate when this height is achieved. At this time, the dial is read to obtain tension measurements. Next, the pressure is increased until the valve open height is obtained, and the tension gauge is read again. Valve Guide Renewing Equipment.  Whenever the cylinder head and valves are reconditioned, always check the valve guide for wear. If the guide is worn or damaged, there are three common methods of renewing the guide: knurling, inserts, and replacement. Knurling is a two-step process of returning the valve guide to its proper bore. First, a knurl bit is driven into the guide, using a drive reduction attachment for a drill. The knurl bit forces the metal to rise and decrease the bore diameter (Figure 2-66). The peaks of

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Valve guide Valve guide reamer

Figure 2-66  The knurling bit raises areas of the valve guide to decrease the bore diameter.

Figure 2-67  After knurling, the bore is reamed to the proper diameter.

the rises create a diameter smaller than the diameter of the valve stem. The next step is to ream the bore to specifications (Figure 2-67). If the guide is excessively worn, it cannot be resized by knurling. Also, knurled guides wear faster than other methods of guide repair. The preferred method is to install valve guide inserts or replacement guides. These can be installed using hand tools; however, high-volume shops may have cylinder head reconditioning machines that perform most operations at one setup. The insert can be a bronze or cast-iron spiral coil, sleeve, or thin wall tube type. If the cylinder head is equipped with inserts, they can be driven out and the new ones installed. The new insert must be reamed to the proper size. To install the bronze spiral coil insert, a special tap is used to cut an oversized thread into the guide. Next, the proper length of spiral coil is threaded into the guide bore. The coil is forced into the guide by use of a swaging tool. A reamer is then used to restore the correct bore. The bronze sleeve and thin wall tube-type inserts are installed by reaming the guide to the proper diameter required for the insert. The sleeve is then driven or pressed into the guide. A swaging tool is used to force the sleeve into contact with the guide. The last step is to ream the insert to the proper diameter. On most aluminum cylinder heads, the old guides can be driven out using a guide punch and a hammer. Some manufacturers specify that the head be heated before guide removal; always follow the manufacturer’s service information. The new guides are already properly sized and are driven or pressed in. Seat Grinder.  Worn or damaged valve seats may be reconditioned. A common method of repair is to grind the seat to provide a new surface. The most common type of valve seat grinder is the concentric style (Figure 2-68). It provides a full contact on the seat, allowing the entire circumference of the seat to be ground in one motion. The beveled grinding wheel is attached to a special holding fixture with a hollow center. The hollow center is placed over a pilot shaft inserted into the valve guide. The pilot shaft centers the stone onto the valve seat (Figure 2-69). The grinding stone is driven by a special high-speed motor that turns about 1,800 rpm. Grinding stones are available with different angles. Use the angle specified by the engine manufacturer. To properly resurface the valve seat, the grinding stone must be dressed before use. It may be necessary to dress the stone again during the resurfacing operation.

Most valve guide reamers come in sizes 0.001 inch apart.

Caution Before grinding the valve seat, check the valve guides for wear. It is important that the pilot shaft be properly centered. A worn guide will result in off-center grinding of the valve seat.

WARNING  Always wear eye protection whenever using a seat grinder. Particles discharged from the seat grinding stone may cause eye injury. Also, do not use any machinery or equipment without first receiving proper instruction. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Grinding wheel Valve seat Valve guide

Pilot shaft

Figure 2-68  Typical valve seat grinder.

Figure 2-69  The seat grinding stone is centered onto the seat by a pilot shaft inserted into the valve guide.

Seat Cutter.  Another method of resurfacing the valve seats is to use a seat cutter. The valve cutter uses carbide cutters to cut a new surface (Figure 2-70). The cutter can be hand operated or driven by a low-speed motor turning about 60 rpm. Three-angle blades are available to cut the valve seat in one operation. WARNING  Always wear eye protection whenever using a seat cutter. Small metal particles may fly upward toward your face.

Seat Inserters.  If there is not enough material to resurface the valve seat, the valve seat is excessively worn or cracked, or if the valve stem tip installed height has increased more than 0.060 inch, it may be possible to install a seat insert. If the cylinder head is equipped with insert seats, they are knocked out first. The replacement insert is slightly larger than the original. Before installing the new insert, the counterbore must be enlarged using a special bit (Figure 2-71). This bit is also used to counterbore cylinder heads with integral seats.

Cutters

Figure 2-70  A valve seat cutter uses carbide bits to cut a new seat surface.

Figure 2-71  A special counterbore bit is used to prepare the cylinder head for valve seat inserts.

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Engine Rebuilding Tools and Skills

Once the counterboring is completed, a driver is used to install the insert. A guide is installed to ensure proper centering of the insert; then a hammer is used to impact the driver and seat the insert. Most inserts are interference fit to prevent movement, usually 0.006 in. (0.150 mm) to 0.008 in. (0.200 mm) for inserts installed into aluminum heads and 0.004 in. (0.100 mm) to 0.005 in. (0.125 mm) for inserts installed into cast-iron heads. This means that the diameter of the seat insert is actually larger than the diameter of the bore it will be pressed into. WARNING  Always wear eye protection whenever performing any grinding, cutting, or driving.

Valve Grinding Equipment.  The valve face and stem tip may be reconditioned using special valve grinding equipment (Figure 2-72). A chuck accepts and holds the valve stem. The chuck is mounted on a sliding surface that is moved by a lever. The angle of contact between the valve face and grinding stone is adjustable. Use the engine manufacturer’s specifications to determine the correct face angle. The valve rotates with the chuck when the motor is turned on. The operator uses the lever to move the valve face across the grinding stone. Some valve grinding equipment has a second grinding wheel used to refinish the valve stem tip. WARNING  Always wear eye protection whenever using any valve grinding equipment.

Head Resurfacing Equipment.  The mounting surface of the cylinder head to the block must be flat. Over a period of time, or if the engine overheats, this surface may become warped. Other reasons to resurface the cylinder head are to raise the compression ratio and to square the deck to the bores. Some shops resurface the cylinder head with a belt surfacer. This method uses a belt that operates similar to a conveyor belt. The head is placed on the belt and held in position by a restraint rail. The operator applies hold-down pressure while slightly moving the cylinder head on the belt to achieve the desired surface finish (Figure 2-73). Using the belt surfacer has disadvantages. This method does provide uniform finishing, but it does not square the head (Figure 2-74). For these reasons, the preferred method is to resurface the cylinder head using cutting bits. The milling machine uses large rotating cutters to remove thin layers of material (Figure 2-75). The cylinder head is mounted to a table. Depending on the type of milling machine, either the table is moved below the

Figure 2-72  Typical valve grinder used to recondition the valve face and tip.

Belt surfacers reface the cylinder head surface using a special type of sanding paper. A broach refaces the ­cylinder head using metal blades.

Figure 2-73  Using a belt-type sander.

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B

A

Cylinder head surface before resurfacing A.

B

A

Figure 2-75  A milling machine uses cutters to remove layers of material from a cylinder head or block.

Cylinder head surface after resurfacing with belt. Does not square the head. B.

Figure 2-74  A belt resurfacer will not square the cylinder head.

A profilometer ­electrically senses the distances between peaks to determine the finish of a cut. A microinch is ­one-millionth of an inch. The microinch is the standard measurement for surface finish in the U.S. Customary system. A micrometer (one-­ millionth of a meter) is the standard measurement for surface finish in the metric system.

cutters, or the cutters move across the head. Usually about 0.005 in. (0.127 mm) is removed with each pass. The desired finish cut is achieved by changing the speed and depth of cut. If the cutters are mounted below the table, the machine is called a broach. Like the milling machine, the cutters move in a horizontal plane. The cylinder head is mounted to the table, which moves over the cutters. Another common style of resurfacer is the surface grinder. The surface grinder can be used to resurface cylinder heads or engine blocks (Figure 2-76). The head is mounted to an adjustable table, and coolant is pumped onto the workpiece as the table moves below the grinder wheel. About 0.002 in. (0.050 mm) is removed with each pass. When the grinder completes a pass resulting in a smooth surface, additional passes are made without any further metal being removed. This provides a finish on the surface and ensures that the surface is straight. WARNING  Always wear eye protection whenever resurfacing a cylinder head or block.

Profilometers can be used to measure the surface roughness after the machining operation is completed. A stylus is moved across the surface, and the profilometer ­measures the distance between the peaks and valleys of the cuts. For proper head gasket sealing, a finish between 60 and 120 microinches is desirable for most applications. Some

Figure 2-76  Some surface grinders can be used to resurface the engine block. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.

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manufacturers specify a surface finish as smooth as 20 microinches, so always check the service information for the application you are working on.

Engine Block Reconditioning Equipment During engine rebuilding, special tools and equipment are used to properly disassemble, assemble, and recondition the engine block. Some of these tools include the following: ■■ Camshaft bearing remover and installer ■■ Ridge reamer ■■ Cylinder boring equipment ■■ Cylinder hone ■■ Align boring equipment ■■ Block resurfacing equipment Camshaft Bearing Remover and Installer.  The type of camshaft bearing remover and installer used depends on the engine design. Most OHV engines, with the camshaft in the engine block, will use a bushing driver and hammer (Figure 2-77). The correct size mandrel is selected to fit the bearing. Turning the handle tightens the mandrel against the camshaft bearing. Then the bearing is driven out by hammer blows. The same tool is used to replace the bearings. Some OHC engines require a special puller/installer (Figure 2-78). Ridge Reamer.  As the piston moves within the cylinder, the rings cause wear on the cylinder walls. The greatest amount of wear is near the top of the travel due to the high pressures, high temperatures, and little lubrication in this area (Figure 2-79). The resultant ridge must be removed before attempting to remove the pistons from the block. This ridge is removed using a ridge reamer (Figure 2-80). When using a ridge reamer, do not remove any more material than necessary to remove the pistons. WARNING  Always wear eye protection whenever using a ridge reamer.

Cylinder Boring.  If the cylinder bore is excessively worn, tapered, or out-of-round, it may be bored to the next piston size. In addition, cylinder boring may be performed to increase the displacement of the engine. The boring process causes surface fractures that extend to a depth from 0.0005 to 0.001 in. (0.01 to 0.02 mm). For this reason, the cylinder is bored to a size 0.003 in. (0.05 mm) smaller than required. The additional material is removed during the honing process. The bore machine has a feed mechanism that moves the rotating cutters through the cylinder.

Camshaft bearing

Puller

79

Caution Never attempt to remove and install OHC bearings by using a bushing driver. The aluminum bearing supports may become damaged, bent, or broken due to the hammer blows.

Caution Attempting to remove the pistons before removing the ridge may result in damage to the rings and ­piston lands. Also, damage to new rings may result if they are installed without the ridge removed. A ridge reamer is a ­cutting tool used to remove the ridge at the top of the cylinder.

Boring is the process of enlarging a hole.

Holes must be aligned at the time of installation.

Figure 2-77  Typical camshaft bearing tool used for camshaft bearings Figure 2-78  A special camshaft bearing puller/installer is used on in the block. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, OHC engines. or duplicated, in whole or in part. WCN 02-300

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Chapter 2 Original bore Ring ridge

Tapered cylinder

Figure 2-79  Piston ring contact on the cylinder wall causes a ridge to be formed.

Figure 2-80  Use a ridge reamer before removing the pistons, to prevent damage to the pistons.

WARNING  Always wear eye protection whenever using a cylinder bore.

Cylinder Hone.  After the cylinder is bored, it must be honed to obtain proper ring and cylinder seating. The rigid cylinder hone uses two to four abrasive stones to remove cylinder wall material (Figure 2-81). When the adjustment nut is turned, it forces the stones outward toward the cylinder walls. The nut is adjusted until the stones contact the walls, then the hone is driven by a heavy-duty drill motor. As the stones are rotated in the ­cylinders, the hone is also moved up and down.

Figure 2-81  A cylinder bore hone. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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81

115° to 135° reference 125° preferred

1

1

22- 2 ° to 32- 2 ° 27- 1° preferred

CL horizontal

2

CL vertical

Figure 2-82  Desired finish pattern after honing the cylinder.

The first passes may be done with coarse stones, while finishing cuts are performed with finer stones. The final finish should have diamond-shaped grooves that cross at 30- to 40-degree angles (Figure 2-82). Another style of hone is the brush hone (Figure 2-83). The round stones at the end of the bristles cut away the material much like the rigid hone. This hone is simpler to use and provides good results; however, this type of hone cannot remove taper or out-ofround from the cylinder bore. The brush hone is used to break the glaze in the cylinder

Caution Always flow honing oil over the work area while honing a ­cylinder. This will help regulate the temperature and wash away metallic residue.

Figure 2-83  Use a brush hone to deglaze the cylinder wall. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Torque plate

Figure 2-84  A torque plate is used to prestress the block prior to boring or honing the cylinders.

and provide a new surface finish. The smoothness of the surface finish depends on what type of rings will be used. Some manufacturers do not recommend the use of a brush hone. Refer to service information from the manufacturer and the ring supplier to achieve the proper cylinder finish.

Torque plates are metal blocks about 2 inches thick. They are bolted to the cylinder block at the cylinder head mating surface to prevent twisting during honing and boring operations.

The align hone is able to hone all bearing bores at the same time to realign them.

Caution Straightening the crankshaft may result in cracks. Carefully inspect the crankshaft after straightening. If there are any doubts, do not use it. The crankshaft may be magnetically tested for cracks.

Torque Plates.  During the boring and honing process, the cylinder head is removed. When the head is reinstalled and torqued, it sets up stress that results in dimensional changes. To prevent any alignment problems, many engine manufacturers require a torque plate be attached to the engine block prior to boring and honing of the cylinders (Figure 2-84). The torque plate is installed with the same torque required to bolt the cylinder head to the block. This stresses the block in the same manner as the head. The main bearing caps should also be installed and torqued. Any boring and honing operations will now be true. Align Boring Equipment.  Over a period of time, the main bearing saddles may become warped and out of alignment. To correct this, a boring bar or align boring machine is used. A boring bar is centered in the two main bearing saddles at either end of the block. Before installing the main bearing caps, about 0.002 in. (0.05 mm) is removed from the base of the cap. The boring bar uses cutters to remove material from the main bearing saddles and caps to realign the crankshaft bearing bores. If the crankshaft bores are not excessively misaligned, it may be possible to use an align hone instead of a boring bar. The hone has a long arbor bar with spring-loaded honing stones. First, remove 0.002–0.003 in. (0.05–0.07 mm) of material from the parting surface of the main bearing caps. With the caps installed to the engine block, insert the align hone. A special motor rotates the hone while the arbor is moved back and forth in the bores. WARNING  Always wear eye protection whenever using an align bore bar or machine.

Block Resurfacing Equipment.  As with the cylinder head, the engine block deck may require resurfacing at the mating surfaces of the head gasket. Generally, the same equipment used to mill or grind the cylinder head is used to resurface the block.

Crankshaft Reconditioning Equipment To correctly determine if the crankshaft is straight, a dial indicator is used in conjunction with V-blocks. With the dial indicator on the center main bearing journal, the crankshaft is rotated through one complete revolution. Total movement of the indicator needle is the

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-85  Crankshaft grinder.

83

Figure 2-86  Crankshaft polisher.

bow of the crankshaft. Always check the results with the manufacturer’s specifications. While the crankshaft is set into the V-blocks, check the flywheel flange and vibration dampener mounting surface for runout. If the crankshaft is bent, it is usually replaced. In some cases when the crankshaft is antique or custom-made, it can be straightened using a specialized press. Crankshaft Grinder.  If the main and connecting rod journals are worn or damaged, the surface can be reconditioned by using a crankshaft grinder (Figure 2-85). The grinder gradually removes the material from each journal until it is perfectly round and smooth. Crankshaft Polishers.  After the crankshaft journals have been resurfaced, they must be polished. The crankshaft polisher is like a belt sander with fine grit paper and may be attached to the crankshaft grinder (Figure 2-86). The polisher smooths the surface of the journals to provide a low-friction surface for the bearings.

Classroom Manual Chapter 12, page 240

Crankshaft Balancers.  A crankshaft that is out of balance will result in vibrations. When balancing the crankshaft, there are two major concerns: the reciprocating weight of the pistons and connecting rods, and the rotating weight that turns around the axis of the crankshaft. To balance the crankshaft, it is installed to a special balancer (Figure 2-87). If the crankshaft is out of balance due to a heavy counterweight, a hole is drilled in the counterweight to lighten it. If the counterweight is too light, a hole is drilled in the counterweight and a heavy metal plug is inserted.

Connecting Rod and Piston Reconditioning Equipment There may be instances in which the connecting rod or piston may need to be reconditioned. The bore of the connecting rod may need to be resized due to wear. The most common tools and equipment used to recondition connecting rods and pistons include the following: ■■ Pin drift ■■ Ring end-gap grinders ■■ Pin hole machine ■■ Rod aligner ■■ Rod cap grinder ■■ Rod heaters Pin Drift.  A piston pin drift is used to remove press fit piston pins (Figure 2-88). Pin drifts are available in assorted sizes to accommodate the different sizes of piston pins. When using the pin drift, it is important to properly support the piston assembly to ­prevent damage to the piston.

A piston pin may be called a wrist pin.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-87  A special crankshaft balancing machine.

Figure 2-88  Piston pin drift set.

Figure 2-89  This type of ring grinder helps when correcting ring end gap.

Ring End-Gap Grinders.  If the ring end gap is smaller than specifications, in some cases it can be enlarged by removing some of the ring material. This may be accomplished by use of a file or by a special ring end-gap grinder (Figure 2-89). Many ring end-gap grinders are portable units that are secured into a vise. A crank is turned to rotate a small grinding wheel that removes material from the ring. WARNING  Always wear eye protection whenever using a grinder.

Pin Hole Machine.  Worn connecting rod piston pin bosses or big end bores can be corrected using a special rod honer (Figure 2-90). Like honing the main bearing bores, this process removes very little material with each pass. An abrasive stone is rotated inside the bore while cooling oil is pumped over the workpiece. The operator moves the connecting rod over the full length of the stone. Measurements are taken regularly until the desired diameter is obtained.

A rod honer is a machine that hones (precision scratches) the connecting rod.

A rod aligner measures connecting rod twist and bend.

Rod Aligner.  A connecting rod that is twisted or bent will result in early failure of the rings, piston, cylinder wall, and rod bearings. A rod aligner makes it possible to straighten some bent connecting rods (Figure 2-91). Rod Cap Grinder.  Worn connecting rod saddles and caps may be restored to their ­original size. To do this, material is removed from the cap and the connecting rod saddle at the parting surfaces. Usually about 0.002 in. (0.05 mm) is removed from each surface. This makes the bore smaller than specifications. The bore is restored to standard size by honing.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-90  Connecting rod honer.

Figure 2-91  A rod aligner can be used to check and straighten some connecting rods.

Rod Heaters.  Pressing interference fit piston pins into the connecting rod bore can damage the piston. A rod heater is used to heat the small end of the connecting rod and provide easier assembly of the rod to the piston without having to press in the pin. When the small end of the rod is heated, the bore expands, allowing the piston pin to be pushed into place. When the rod cools, the pin is locked into place.

WORKING AS A PROFESSIONAL TECHNICIAN Before you are given the responsibility of rebuilding an engine, you will need to prove yourself as an excellent general service technician. Once you have proven that you consistently perform quality work and pay attention to details, you may be given major engine work. Overhauling an engine is an expensive proposition for the consumer, and no shop owner wants to have major work come back with a defect. In today’s service industry, many engines are replaced with remanufactured units rather than rebuilt in-house. These come with a written warranty that protects both the consumer and the shop owner if the engine fails. Whether you rebuild or replace an engine, you may generate repair bills in excess of $3,000. Your work is expected to hold up for many thousands of miles. A seemingly small oversight during diagnosis, assembly, or installation could cause catastrophic engine failure. When your physical work is complete, you will need to describe your work effectively to the manufacturer, your service advisor, and the customer. Engine repair work is performed by professionals; learn to work and act as a professional technician.

Education Your training to become a professional automotive technician is critical to your success. You must have a solid technical education and a well-rounded general education. You are required to understand a huge amount of technical information and to regularly interpret new information. As soon as you leave school, you will need to find ways to keep your training up to date (Figure 2-92). Specialized skills required to repair engines must be accompanied by a thorough understanding of automotive systems. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-92  Reading professional periodicals can help you keep your knowledge up to date.

A warranty repair means that the manufacturer reimburses the shop for the parts and labor to make a repair.

Your ability to perform mathematical functions is essential; an error of one-­thousandth of an inch (0.001 in.) could destroy an engine repair. Accuracy in measurements, interpretation of specifications, and conversion of numbers are all required skills. Additionally, the problem solving and analytical thinking used in math will be useful in almost every repair job. When you approach a vehicle problem, you will need to analyze the situation and filter information to guide you through a logical process of determining the cause. When an engine comes in with a serious internal defect, you must analyze potential causes and be sure that you correct the source of the problem, not just the symptom. Overheating, for example, can seriously damage an engine. If you were to install a remanufactured engine without replacing the restricted radiator, you could wind up with a very unhappy customer and boss. Your diagnostic process must be logical, thorough, and effective for you to be successful. You also need excellent communication skills. When performing a warranty repair, it is your responsibility to effectively describe the customer concern, the cause of the problem, and all the necessary corrections. The manufacturer relies on the information you provide on the repair order to determine whether it will reimburse the dealer for the parts and labor required for the job. Failure to properly document your engine work could cost your employer thousands of dollars. Repair information is also kept on file so that vehicle history is available when other repairs are needed. It is also extremely important that you can communicate effectively with your service advisors, service manager, and customers. You will need to be able to explain technical information in a way that laypeople can understand. Your service advisors rely on your description of your work to provide information to the customer. Often, particularly with large jobs such as an engine overhaul or replacement, the customer will want to speak directly with the technician (Figure 2-93). You must be able to professionally and effectively describe your work to customers.

Professionalism From the moment you begin repairing vehicles, either as a student or a paid professional, the image you portray will help define your role in the shop, your rate of pay, your opportunities for advancement, and your overall success in the automotive industry. Clean work uniforms, proper language and behavior, and excellent communication skills will help develop your image as a professional service technician. Your presentation helps you as an individual and the service industry as a whole. When you dress, behave, and speak like a professional, you will be treated and paid accordingly. There will be times when you are frustrated with a job. Take a short break and walk away before losing your cool. Profanities will not loosen a bolt or help your career. Your Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-93  Explain your repair fully and professionally to gain respect and trust from your customers and coworkers.

employer, a potential employer such as a manufacturer’s representative, or a customer could be in earshot at any time. It will damage your image and potential if they hear a string of foul language coming from you. Keep yourself and your work area clean; you should always be prepared to present yourself to a customer. Neither your employer nor your customers want a filthy technician in a nice vehicle. Customers’ vehicles are typically their second-largest investments; they want a professional to provide service. You can perform the best engine repair, but leave a spot of grease on the driver’s seat and the customer will be unhappy with the whole job (Figure 2-94). Your ability to communicate well with your service advisors, your employer, and your customers is essential to your career. If you can’t describe your work professionally, you simply won’t get that work. The more complex and in-depth the job, the more critical it is that you can explain your diagnosis and repair to management and your customers. When performing engine repairs, you’ll need to explain why the problem occurred, how you found it, and what you did to correct it. If you are discussing an engine rebuild, you are trying to “sell” thousands of dollars of work. Your employer relies on your explanations to get authorization for the job. Imagine the different effects the two following explanations might have on a customer deciding to have the work performed at your shop. In the first case, the technician says, “The engine blew; I’ll have to totally overhaul it. It will probably cost around $2,000.” In the second case, the technician says, “Two cylinders have low compression caused by worn piston rings. This is the cause of your lack of power. Usually when the rings are worn, other components in the engine also need service or replacement. Once we disassemble and evaluate the engine, we can offer you specific repair options. In the worst case, a thorough engine overhaul or replacement may be needed; this could cost upward of $2,000.” Who is the customer more likely to trust? If you were the boss, which technician would you choose to perform the work? Offer your customers and your management respectful and professional communication; they will respond in kind.

Compensation You have the opportunity to enter a rewarding profession. Your skills are in high demand; rarely will a competent technician have any difficulty securing work. Skilled technicians can make a very comfortable wage. Your pay will increase as your skill level improves. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-94  This customer would not appreciate a smudge of grease on her spotless interior.

Straight time pay means that you are paid for every hour you are physically at work, regardless of your productivity.

Flat rate pay means that you are paid for each hour of billable work as determined by the manufacturer, an aftermarket labor-­ estimating guide, or your shop.

Most technicians start out working for straight time pay. This means that you will be paid a dollar amount for every hour that you are at work. This gives you a chance to learn the shop practices and develop some speed in repairing vehicles. Some technicians will work for an hourly wage throughout their careers. A technician who performs primarily diagnostic work or electrical work will often be paid straight time. Sometimes those who overhaul engines are paid straight time, too. The employer understands that the speed of the overhaul is not nearly as critical as thoroughness and attention to detail. Many shop owners will change your method of payment to flat rate pay when they determine that you will be productive on this system. When you are paid flat rate, it means you get paid by the job hour. If, for example, a vehicle needs a head gasket, the service advisor will look up the flat rate time and quote that amount of labor to the customer. When you do the job in 6 hours rather than the quoted 8 hours, you will be paid for 8  hours. Your billable hours for the week are added up to calculate your pay. If you ­produced 56 hours’ worth of work while actually working for only 45, you will be paid for 56 hours. In a strictly flat rate shop, this can also work to your disadvantage. If a few jobs take you much longer than the posted flat rate time, you may actually be paid for fewer hours than you worked that week. This could happen, for example, if you replace a timing belt on a vehicle one week and the next week it comes in with a snapped timing belt. Many shops will not pay you again to repair a “come back”; if your service failed, you can be held accountable and repeat the job without getting paid hours for it. This is just one of the many reasons why it is critical to perform quality work. Some shops use a combination of the two forms of payment. They may guarantee you a certain number of base hours per week and pay you extra for increased production. This ensures that the technician is adequately compensated every week,

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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regardless of the type or quantity of work available. It also serves as an incentive to be as productive as possible.

ASE Certification The National Institute of Automotive Service Excellence (ASE) offers a well-recognized national certification program for automotive technicians. The standardized ASE tests are offered in eight basic areas of automotive repair as well as in several specialized and advanced areas. When you pass all eight basic tests, you become an ASE-certified master automotive technician. Engine repair is one of the eight core tests needed to become a master technician. The National Institute of Automotive Service Excellence (ASE) offers nationally recognized certifications to automobile and heavy-duty truck technicians through a combination of biannual testing and proof of professional experience. The ASE tests are CBTs (Computer-Based Tests) offered at testing centers all across the country. The tests check your practical knowledge of automotive systems and of diagnostic and repair techniques. To become certified, you must pass the test and prove that you have two years of work experience. If you complete a two-year college program in automotive technology, it will substitute for one year of experience. Once you are certified, you will receive a certificate, a wallet card, and a shoulder patch documenting your achievement (Figure 2-95). Technicians must retake the tests every five years to keep their certifications current. The engine repair ASE test asks questions about general engine diagnosis, cylinder head service, engine block service, cooling and lubrication system repair, and a few questions on fuel, electrical, ignition, and exhaust systems. Test preparation guides and training is available online from ASE. It lists the tasks covered in the test and offers some sample questions. ASE uses three formats of questions: 1. Direct or Completion questions 2. Technician A/Technician B questions 3. Except or Least Likely questions.

Figure 2-95  This ASE-certified technician wears his ASE patch proudly; it is a sign of accomplishment.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Many of the questions are in the format we use in this Shop Manual: Technician A says that a compression test can locate a weak cylinder. Technician B says that a cylinder leakage test can pinpoint the cause of a low ­compression reading. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B In this question, both technicians are correct, as you’ll learn in upcoming chapters. Successfully answering these questions requires a thorough knowledge of the subject and careful reading. While many technicians find the questions tricky, if you really know the information, the correct answer will usually be clear. The engine repair test is made up of 50 multiple-choice questions in the following areas: Content Area

Number of Questions

Percentage of Test

General engine diagnosis

15

30

Cylinder head and valvetrain diagnosis and repair

10

20

Engine block diagnosis and repair

10

20

Lubrication and cooling systems diagnosis and repair

 8

16

Fuel, electrical, ignition, and exhaust systems inspection and service

 7

14

AUTHOR’S NOTE  Don’t let an ASE-style question make you stumble. There are many of them, both in this book and on the ASE tests, and you should take your time when answering them. Try to use the following method when formulating an answer: First read the sentence(s) at the beginning of the question. Sometimes there is no introductory sentence, but if there is, it should be considered as factual and pertinent to the question. Then read what Technician A says and ask yourself if that technician’s statement is correct. Do not read any what Technician further says until you have ­formulated an answer. Knowing if Technician A is correct or not will allow you to eliminate half of the answers. Then read Technician B’s statement and ask the same question, is he or she correct? Now you should be able to answer the question easily because you have already eliminated half of the answers. Try this technique and see if it works for you. It may help you not become confused even though you may know the answer.

The ASE tests are written by industry experts: technicians; technical service experts; vehicle, parts, and tool manufacturers; and automotive instructors. Each question must be accepted by each member of the board and then tested on a sample of technicians. The tests do a good job of checking your technical knowledge. Certification is voluntary, but most employers prefer to hire ASE-certified technicians. ASE certification shows your employer that you are knowledgeable and motivated to excel (Figure 2-96). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-96  This tech and her shop boast the blue seal of excellence.

Skills Required for Engine Repair Special skills are required to succeed at engine repair. You must thoroughly understand engine operation and design to effectively diagnose problems. For example, you’ll need to remember how critical engine breathing is to proper performance when diagnosing a low-power condition as a restricted exhaust system. Your study and practice of the information and procedures described in this text will provide you with a solid base of engine operation, diagnosis, and repair knowledge. You must learn to thoroughly diagnose an engine problem before attempting a repair. Don’t attempt to guess—test. We describe many different diagnostic procedures to pinpoint the cause of engine problems. Study and practice these tests now so you will be competent at them in the shop. The customer should receive a realistic quote for engine work; you should not get halfway through the job and then realize that more significant work is needed. Performing the proper tests before disassembly will allow you and your service advisor to estimate the required work. They will also help you locate the root cause of the problem so that your repair is 100 percent effective. Many repair procedures use special tools that you must master to become skilled at engine repair. An engine overhaul requires thorough preliminary diagnosis, accurate measurement with special tools, precision machining and refinishing, and careful torque and assembly techniques. You must be competent at all the techniques to complete the overhaul. In many cases, a significant portion of these repairs will be performed at an engine machine shop. In many cases, your diagnosis will uncover engine problems that may be more easily and cost-effectively resolved with a rebuilt engine. These “crate” engines are delivered to your shop fully assembled except for all the accessories, such as water pumps, generators, and electronic components. This type of repair is clearly the trend in the industry, due to the high cost of labor and individual parts. The crate engines come with a warranty, so Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 2-97  Careful measurement and observation are essential for quality engine work.

the shop is not responsible for the cost of repairs if the rebuild were to fail. This makes your job of diagnosis even more critical; you certainly wouldn’t want to install a “new” engine if the problem is not actually an internal engine failure. You will carry much of the responsibility for determining whether the engine should be repaired or replaced. Equally as important as your technical skills is your attitude. An engine repair technician must be patient enough to be extremely thorough. You cannot rush through critical engine measurements and expect accurate results. You need to thoroughly evaluate the problem and complete each step required for repair (Figure 2-97). Your attention to detail is essential to your success. Locating a cracked cylinder head requires close inspection. Forgetting to analyze the engine bearing wear patterns could cause you to miss a problem that would damage your freshly rebuilt engine. Aside from taste, all your senses are useful during engine diagnosis. Listen for abnormal noises before disassembly; smell the engine oil for signs of contamination or overheating; look carefully at each part for clues about the causes of ­failure; and touch the cylinder walls, crank journals, and valve stems to feel for wear. Use logical steps to analyze and repair faults. A haphazard approach to engine repair will likely cause you to miss something critical. You will learn all the steps required to fully analyze and overhaul an engine; keep notes on the steps that you can refer to when you perform your first several overhauls. If you forget one step, such as measuring crankshaft end play, the engine could come apart within the first few hundred miles of operation. Keep yourself well organized. Label brackets and wires and hoses when you remove the engine or cylinder head. Many technicians put the bolts removed during disassembly loosely back in position or label them in bags. Locating the proper bolts for the timing cover could become a time-consuming and frustrating task if you just dump all the hardware into one bin. Organize your engine measurements into a “blueprint,” so that you can look at all the data to determine what repairs need to be made. If you don’t write your results down as you go along, you will forget some information and have to repeat the procedure. You will need documentation to justify your repairs for warranty purposes or for the customer. As an engine repair technician, you will need patience to work your way through the big job of diagnosing and repairing an engine’s mechanical failure. Honesty is essential when building your reputation. No one wants to pay for unneeded work. Your employer does not want to be caught in a lie to the customer. Be realistic about your estimation of what is required for the repair. If you minimize the work, you will have Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

to come back to the customer later to get authorization for the additional work. If you overestimate the necessary repairs, the customer could get a more realistic quote elsewhere. That customer will never return. If you make an honest mistake, offer an honest explanation. Don’t try to cover up mistakes with unprofessional work. All technicians make mistakes; you will too. What separates the excellent technicians from the shoddy ones is how they deal with the mistake. Mastery as an engine repair technician requires technical knowledge, hands-on experience, and good work habits. If you enjoy engine work, learn and practice the diagnostic and repair techniques presented here. Then always remember how essential your professional attitude is to your success. Engine repair is a challenging and rewarding part of automotive service; aim for excellence.

SERVICE INFORMATION Service information is one of the most important tools for today’s technician. It provides information concerning engine identification, service procedures, specifications, and diagnostic information. In addition, service literature provides information concerning wiring harness connections and routing, component location, and fluid capacities. Service information can be supplied by the vehicle manufacturer or through aftermarket suppliers. Manufacturers supply most of their service information electronically. Service ­information is provided mostly on the Internet and the material is updated regularly (Figure 2-98). Most dealerships retain an archive of service information for older vehicles. Manufacturers also have their service information available on the Internet. This information is available to technicians working in the manufacturers’ dealerships. It is also available to any individual for a fee. A list of automobile manufacturers’ service information websites is available at www.nastf.org. Pricing is based on a one day, one month, or an annual subscription. Manufacturers also provide training materials to their service technicians. Many use Internet-based training for new product and new system updating. Additionally, manufacturers may offer hands-on training seminars in different regions. Technicians working in aftermarket repair facilities have a more difficult time accessing adequate service information for all vehicles. There are a few comprehensive subscription-based information providers. ShopKey and AllData, for example, are service information systems that provide repair information for foreign and domestic vehicles

Figure 2-98  Computers are replacing paper service information in many shops. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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back to 1982. Service information for different years of vehicles or for particular types of service is also available. Some shops subscribe to a telephone-based troubleshooting service. When a technician has a difficult diagnosis, he can call a tech-line specialist who will help troubleshoot the problem. To obtain the correct information, you must be able to identify the engine you are working on. This may involve using the vehicle’s vehicle identification number (VIN). This number has a code for model year and engine. Which numbers are used varies between manufacturers, but the service information will provide instructions for proper VIN usage. The service information may also assist you in engine identification through the interpretation of casting numbers and marks on the block or cylinder head. With the engine properly identified, the required information can be retrieved. In the past, each manufacturer and manual publisher used its own method of organizing its manuals. Recent guidelines now require manufacturer service information to have a standard organization (Figure 2-99). General Information Information that applies to all systems in group (i.e., description of how to use the group). Description and Information Technical information in a system or component operations. Diagnosis and Testing Complete diagnosis and testing for any serviceable component. If the component is diagnosed with the DRB III scan tool, then the component will be diagnosed using the diagnostic procedures manual. VEHICLE GROUP

Services Procedures Any procedure that does not fit the descriptions of removal and installation, disassembly and assembly, cleaning and inspection, or adjustments (e.g., the fuel system pressure release procedure). Removal and Installation Removal and installation of major components. Disassembly and Assembly Cleaning and Inspection Adjustments Schematics and Diagrams Specifications Special Tools

Figure 2-99  Uniform service information layout.

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Engine Rebuilding Tools and Skills INSPECTION 1. Measure the diameter of the piston pin. Piston pin diameter: Standard 20.994 to 21.00 mm (0.8265 to 0.8268 in.)

3. Measure the piston-to-pin clearance. If the piston pin clearance is greater than 0.022 mm (0.0009 in.), remeasure using an oversized piston pin.

2. Zero the dial indicator to the piston pin diameter. 4. Check the difference between piston pin diameter and connecting rod small end diameter.

Figure 2-100  A step-by-step procedure for inspecting the piston assembly components.

Procedural information provides the steps necessary to perform the task. Most service information provides illustrations to guide the technician through the task (Figure 2-100). To get the most out of the service information, you must use the correct information for the specific vehicle and system being worked on, and follow each step in order. Some technicians lead themselves down the wrong trail by making assumptions and skipping steps. Torque, end play, and clearance specifications may be located within the text of the procedural information. In addition, specifications are provided in a series of tables

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TORQUE SPECIFICATIONS Fan Assembly Motor-to-Fan..................................................... 3.3 Nm (29 lbs. in.) Fan-to-Radiator Support Bolt .................................................. 9 Nm (80 lbs. in.) Hose Clamps Heater Hose .......................................................................1.7 Nm (15 lbs. in.) Radiator Hose..................................................................... 3.4 Nm (30 lbs. in.) Lower Air Deflector to Impact Bar............................................ 2 Nm (18 lbs. ft.) Throttle Body Inlet Pipe Bolt 3.1 liters (VIN T) ........................ 25 Nm (18 lbs. ft.) Transmission Oil Cooler Fittings at Radiator ........................... 27 Nm (20 lbs. ft.) Trans. Oil Cooler Pipe Connections (Alum. Radiator).............. 20 Nm (15 lbs. ft.) Radiator Outlet Pipe to Block 2.01 (VIN K).............................. 27 Nm (20 lbs. ft.) Radiator to Radiator Support Bolts.......................................... 10 Nm (90 lbs. in.) Thermostat Housing Bolts 2.0 liters (VIN K) & 3.1 liters (VIN T)................................... 27 Nm (20 lbs. ft.) Coolant Pump-to-Block Bolts 2.0 liters (VIN K).................................................................. 25 Nm (19 lbs. ft.) 3.1 liters (VIN T).................................................................. 24 Nm (18 lbs. ft.) Coolant Pump-to-Front Cover Bolts 3.1 liters (VIN T) ................................................................. 10 Nm (90 lbs. in.) Coolant Pump Pulley-to-Pump Bolts 2.0 liters (VIN K) ................................................................. 24 Nm (17 lbs. ft.) 3.1 liters (VIN T) ................................................................. 21 Nm (15 lbs. ft.) Surge Tank Bolts ..................................................................... 4 Nm (15 lbs. ft.) Surge Tank Pipe to Block Bolt 3.1 liters (VIN T)....................... 8 Nm (70 lbs. in.) Temperature Sending or Gauge Unit ...................................... 27 Nm (20 lbs. ft.) Figure 2-101  Service information provides specification tables.

(Figure 2-101). The heading above the table provides a quick reference to the type of specification information being provided. Diagnostic procedures are often presented in a chart form or a tree (Figure 2-102). The tree guides you through the process as system tests are performed. The result of a test then directs you to a branch. Keep following the steps until the problem is isolated. Since the service information is divided into several major component areas, a table of contents is provided for easy access to the information. Each component area of the vehicle is covered under a section in the service information (Figure 2-103). Using the table of contents identifies the section to refer to. Once in the appropriate section, a smaller, more specific table of contents will direct you to the page on which the information is located. Service procedures may change in midyear production, or problem components may be replaced with new designs, and so on. Technical service bulletins (TSBs) ­provide up-to-date corrections, additions, and information concerning common problems and their fixes. TSBs can save hours of work for the technician. These days many symptoms may be cured by reprogramming the PCM. Trying to resolve the customer concern without the appropriate TSB may not even be possible.

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Engine Rebuilding Tools and Skills

DOES THE ENGINE START?

NO

YES

1

2

-IGNITION “OFF.” -DISCONNECT EMC CONNECTORS. -IGNITION “ON.” -PROBE CKT 419 WITH TEST LIGHT TO GROUND. IS THE “CHECK ENGINE” LIGHT ON?

YES

-IGNITION “OFF.” -DISCONNECT ECM CONNECTORS. -IGNITION “ON.” -PROBE CKTs 2 & 439 WITH TEST LIGHT TO GROUND. IS THE LIGHT “ON” FOR BOTH CIRCUITS?

NO YES

FAULTY ECM CONNECTION OR ECM.

3 CHECK: *BLOWN GAUGES FUSE. *FAULTY CONNECTION. *FAULTY BULB. *OPEN CKT 419. *CKT 419 SHORTED TO VOLTAGE. *OPEN IGNITION FEED TO BULB.

NO

FAULTY EMC GROUNDS OR ECM.

4

REPAIR OPEN IN CIRCUIT THAT DID NOT LIGHT THE TEST LIGHT. IF A FUSIBLE LINK OR FUSE WAS BLOWN, LOCATE AND CORRECT THE SHORT TO GROUND ON THAT CIRCUIT.

Figure 2-102  A diagnostic tree helps the technician pinpoint the cause of the problem.

CASE STUDY A customer hears a knocking noise from the engine when it is cold. The technician believes the cause is piston slap but needs to confirm the diagnosis. With the cylinder heads removed, the technician uses a dial bore gauge to measure bore size and out-of-round. After comparing the measurements with specifications provided in the service information, the technician finds that a cylinder was oversized. A technical service bulletin concerning this condition recommends replacing the piston with a modified unit. After receiving customer approval, the technician ­performs the needed repair, making sure to properly torque all ­fasteners to the specified value.

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TABLE OF CONTENTS GENERAL INFO. AND LUBE General Information Maintenance and Lubrication HEATING AND AIR COND. Heating and Vent. (non A/C) Air Conditioning System V-5 A/C Compressor Overhaul BUMPERS AND FRONT BODY PANELS Bumpers (See 10-4) Fr. End Body Panels (See 10-5) STEERING, SUSPENSION, TIRES, AND WHEELS Diagnosis Wheel Alignment Power Steering Gear and Pump Front Suspension Rear Suspension Tires and Wheels Steering Col. On-Vehicle Service Steering Col.—Std. Unit Repair Steering Col.—Tilt, Unit Repair DRIVE AXLES Drive Axles BRAKES General Info.—Diagnosis and On-Car Service Compact Master Cylinder Disc Brake Caliper Drum Brake—Anchor Plate Power Brake Booster Assembly ENGINES General Information 2.0 Liter l-4 Engine 3.1 Liter V6 Engine Cooling System Fuel System Engine Electrical—General  Battery   Cranking System   Charging System   Ignition System   Engine Wiring

SECTION NUMBER 0A 0B 1A 1B 1D3

3 3A 3B1 3C 3D 3E 3F 3F1 3F2 4D 5 5A1 5B2 5C2 5D2 6 6A1 6A3 6B 6C 6D 6D1 6D2 6D3 6D4 6D5

TABLE OF CONTENTS Drivability and Emissions—Gen. Drivability and Emissions—TBI Drivability and Emissions—PFI Exhaust System TRANSAXLE Auto. Transaxle On-Car Serv. Auto. Trans.—Hydraulic Diagnosis Auto. Trans.—Unit Repair Man. Trans. On-Car Service 5-Sp. 5TM40 Man. Trans. Unit Repair 5-Sp. Isuzu Man. Trans. Unit Repair Clutch CHASSIS ELECTRICAL, INSTRUMENT PANEL, AND WASHER WIPER Electrical Diagnosis Lighting and Horns Instrument Panel and Console Windshield Wiper/Washer ACCESSORIES Audio System Cruise Control Engine Block Heater BODY SERVICE General Body Service Stationary Glass Underbody Bumpers Body Front End Doors Rear Quarters Body Rear End Roof and Convertible Top Seats Safety Belts Body Wiring Unibody Collision Repair Welded Panel Replacement INDEX Alphabetical Index

SECTION NUMBER 6E 6E2 6E3 6F 7A 3T40HD 3T40 7B 7B1 7B2 7C

8A 8B 8C 8E5 9A 9B 9C 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 11-1 11-2

Figure 2-103  The table of contents directs you to the major component area of the service information.

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Engine Rebuilding Tools and Skills

99

ASE-STYLE REVIEW QUESTIONS 1. Technician A says that the machinist’s rule offers more precise measurements than a micrometer. Technician B says that a dial indicator can be used to measure movement. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. The use of torque wrenches is being discussed. Technician A says that if an adapter is required that increases the length of the torque wrench between the fastener and the handle, the reading must be corrected. Technician B says that extensions that increase the height of the wrench from the fastener will not affect the torque reading, provided they do not twist. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. Technician A says that a small-hole gauge can be used to measure the bore of a valve guide. Technician B says that a valve guide bore gauge can be used to measure the bore of a valve guide. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. The use of a cylinder bore dial gauge is being discussed. Technician A says that when using the rockingtype gauge, the largest reading obtained is the diameter of the bore. Technician B says that most cylinder bore dial gauges are not accurate enough to provide good taper and out-of-round measurements. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Valve spring tension testers are being discussed. Technician A says that when using the type with a needle indicating torque wrench, spring height must be set first. Technician B says to apply pressure on the torque wrench until a click is heard, and then multiply the torque wrench reading by two.

Who is correct? A. A only B. B only

C. Both A and B D. Neither A nor B

6. Technician A says to measure the amount of ­out-of-round of a cylinder, measure the bore in three directions at the same bore depth. Technician B says that when measuring the bore, ­subtracting the smallest reading from the largest, at the same bore depth, will provide the amount of the out-of-round. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. Technician A says that a refractometer can show you the mixture and freezing point of the coolant mixture. Technician B says that you can use a coolant test strip to check the acidity level of a coolant. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that a ridge reamer is used to remove the top ridge in the cylinder. Technician B says that the top ridge must be removed prior to removing the pistons. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 9. Technician A says that torque-to-yield fasteners are used to provide a uniform clamping pressure. Technician B says the use of torque wrenches is only for the inexperienced technician to be used as a learning tool. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that the VIN can be used to identify the engine. Technician B says that a TSB may provide updated service information. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

IDENTIFYING ENGINE SERVICE TOOLS Upon completion of this job sheet, you should be able to properly identify several common engine service repair tools, describe their use and function, and explain how to handle them safely. NATEF Correlation This job sheet addresses the following RST tasks: Tools and Equipment, Task # 1 Identify tools and their usage in automotive applications. Tools and Equipment, Task # 3 Demonstrate safe handling and use of appropriate tools. Tools and Equipment, Task # 4 Demonstrate proper cleaning, storage, and maintenance of tools and equipment. Tools and Materials • Engine service tools Procedure Your instructor will provide you with a variety of common engine service repair tools and equipment. Write down the name of each one; describe one function of each; ­demonstrate the proper cleaning, storage, and maintenance; and demonstrate the safe handling of each one. 1. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 2. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 3. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 4. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 5. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 6. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 7. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ 8. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Proper cleaning, storage, and maintenance _____________________________________ Safe handling procedures ___________________________________________________ Instructor’s Response ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

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Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

USING FEELER GAUGES Upon completion of this job sheet, you should be able to accurately use a feeler gauge to measure valve clearance. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 5 Demonstrate proper use of precision measuring tools (i.e., micrometer, dial-indicator, and dial-caliper). This job sheet addresses the following MLR task for Engine Repair: B.1.

Adjust valves (mechanical or hydraulic lifters).

This job sheet addresses the following AST/MAST task for Engine Repair: B.4.

Adjust valves (mechanical or hydraulic lifters).

Tools and Materials • Feeler gauge set • Technician’s tool set • Engine with adjustable valvetrain Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Using the engine provided, in the spaces below record the valve clearance. 1. Locate the valve clearance specifications in the service information. Intake _______________ Exhaust _______________ 2. What valves can be adjusted with piston number one at TDC compression stroke? _________________________________________________________________________ _________________________________________________________________________ 3. What piston position is required to adjust the remaining valves? _________________________________________________________________________ _________________________________________________________________________ 4. Set the engine to number one at TDC compression stroke, and measure the valve clearance. Record your results below. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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5. Rotate the engine crankshaft until the correct piston listed in step 4 is located at TDC compression stroke. Measure and record the remaining valve clearances below. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Are any of the valves’ clearances out of specification? h Yes h No If yes, which ones, and why? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

READING DIAL CALIPERS Upon completion of this job sheet, you should be able to accurately measure parts with a dial calipers. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 5 Demonstrate proper use of precision measuring tools (i.e., micrometer, dial-indicator, and dial-caliper). Tools and Materials • Dial caliper Procedure Your instructor will provide you with a variety of parts. Use the dial calipers to measure length, width, inside diameter, outside diameter, and depth for each part as needed. Record the measurements in the space provided. 1. Part number one—Length _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Part number two—Width _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Part number three—Inside Diameter _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Part number four—Depth _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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8

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

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9

READING A DIAL INDICATOR Upon completion of this job sheet, you should be able to accurately measure the camshaft lobe lift with a dial indicator. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 5 Demonstrate proper use of precision measuring tools (i.e., micrometer, dial-indicator, and dial-caliper). Tools and Materials • Dial indicator • Camshaft • Vee blocks Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a camshaft and vee blocks. Use the dial indicator and a base stand (magnetic or clamp style) to measure the camshaft lobe lift. Record the measurements in the space provided. 1. Attach the base stand to the dial indicator.

h

2. Put the camshaft on the vee blocks; then position the dial indicator needle on the base of a camshaft lobe and zero the dial.

h

3. Rotate the camshaft, and record the amount of lobe lift. _________________________________________________________________________ 4. Repeat this process on the other camshaft lobes, and record your findings below. _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

USING AN OUTSIDE MICROMETER Upon completion of this job sheet, you should be able to accurately measure parts with an outside micrometer. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 5 Demonstrate proper use of precision measuring tools (i.e., micrometer, dial-indicator, and dial-caliper). Tools and Materials • Outside micrometer set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with a variety of internal engine components. Use the micrometer to measure outside diameter or thickness for each part as needed. Record the measurements in the space provided. 1. Part number one—Outside Diameter _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Part number two—Outside Diameter _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Part number three—Thickness _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Part number four—Thickness _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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5. Part number five—Length _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Part number six—Length _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

MEASURING CYLINDER WALL WEAR Upon completion of this job sheet, you should be able to accurately measure cylinder wall taper and out-of-round using two different methods. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 5 Demonstrate proper use of precision measuring tools (i.e., micrometer, dial-indicator, and dial-caliper). Tools and Materials • Telescoping gauge • Outside micrometer set • Inside micrometer set • Cylinder bore gauge • Engine block Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with an engine block. Use the two different methods as directed to measure a cylinder for taper and out-of-round. Record the measurements in the space provided. 1. Using a telescoping gauge and outside micrometer: a. Measure the bore diameter in three directions at the top of ring travel. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ b. What is the amount of out-of-round? _______________ c. Measure the diameter of the bore at the bottom of ring travel. _______________ d. What is the amount of taper? _______________ 2. Using a cylinder bore gauge: a. Set the bore gauge to the correct bore size. Bore size _______________ b. Set the dial to zero, and lock the extension. c. Measure the bore diameter in three directions at the top of ring travel. d. What is the amount of out-of-round? _______________ e. Measure the diameter of the bore at the bottom of ring travel. f. What is the amount of taper? _______________

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Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

FINDING SERVICE INFORMATION Upon completion of this job sheet, you should be able to properly locate specific service details on the service information or on a computer system. NATEF Correlation This job sheet addresses the following MLR task: A.1. Research applicable vehicle and service information, vehicle service history, service precautions, and technical service bulletins. This job sheet addresses the following AST/MAST task: A.2 Research applicable vehicle and service information, including fluid type, internal engine operation, vehicle service history, service precautions, and technical service bulletins. Tools and Materials • Service information • Computer with automotive service software (i.e., Mitchell on Demand, Shop Key, or AllData) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then locate the following. Note: This Job Sheet may be used in conjunction with Appendix A (engine specifications). 1. What are the bore and stroke of the assigned engine? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What are the torque specifications (in sequence if multiple steps) for the cylinder head? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Are the cylinder head bolts torque-to-yield?

h Yes  h No

4. Is there a tightening sequence for the cylinder head bolts?

h Yes  h No

5. What is the oil capacity of the engine with a new filter? _________________________________________________________________________ 6. What is the oil (bearing) clearance specification for the crankshaft main bearings? _________________________________________________________________________

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7. Locate a TSB applicable to your vehicle, and list the title. _________________________________________________________________________ 8. Describe what the TSB is about. _________________________________________________________________________ _________________________________________________________________________ 9. Locate a service precaution related to the battery, starting, and charging system. List what the precaution found in the service information says. _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Rebuilding Tools and Skills

Name ______________________________________

Date __________________

115

JOB SHEET

13

LOCATING AND UNDERSTANDING TECHNICAL SERVICE BULLETINS Upon completion of this job sheet, you should be able to properly locate specific service details on the service information or on a computer system. NATEF Correlation This job sheet addresses the following MLR task: A.1. Research applicable vehicle and service information, vehicle service history, service precautions, and technical service bulletins. This job sheet addresses the following AST/MAST task: A.2 Research applicable vehicle and service information, including fluid type, internal engine operation, vehicle service history, service precautions, and technical service bulletins. Tools and Materials • Service information • Computer with automotive service software (i.e., Mitchell on Demand, Shop Key, or AllData) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then locate the following. 1. Locate an engine-specific technical service bulletin for the vehicle and engine package you are assigned to.

h

2. What is the bulletin number and the date it was released? _________________________________________________________________________ 3. Are there any updates to this bulletin? _________________________________________________________________________ 4. Describe the process needed to find the TSB. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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5. Explain how you might find this information useful when working on engines. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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CHAPTER 3

BASIC TESTING, INITIAL INSPECTION, AND SERVICE PROCEDURES

Upon completion of this chapter, you should understand and be able to describe: ■■ ■■ ■■ ■■

The differences between basic testing and advanced testing. The basic (initial) engine and vehicle inspections. How to complete a service repair order. How parts and labor are calculated on a repair order.

■■ ■■

■■

The importance of the customer’s ­concern on a repair order. The importance of customer vehicle care through proper use of fender ­covers, mats, steering wheel cover. The importance of the three Cs ­(concern, cause, and correction) on the repair order.

Terms To Know 3Cs Chassis ear Repair order

INTRODUCTION In the engine repair and rebuilding industry, you will be faced with many different challenges, each of which will require a different level and type of skill. Before you can read further into this book and complete most of the job sheets at the end of this chapter, you must be able to properly identify the engine components and understand the variety of the designs. In some cases the technician may have direct contact with the customer, and in some cases the technician may not. Either way, it is important to understand that the customer’s complaint should always be fixed when the job is completed. There are many reported cases where the customer’s complaint, as written on the repair order, does not match the real complaint. Many times, this is because the customer and technician do not know how to communicate together—and the wrong thing gets written down. This then is passed on to the technician who may repair the incorrect item. This is especially true with engine repair. A customer may come into the repair facility with an engine-related noise. The technician may suggest a lengthy and expensive repair, and when the repair is completed, the customer may mention that the noise is still there. Although the expensive repair may have been needed, it was not why the customer came in. This is an example of a lack of communication and understanding of many processes that will eventually lead to the customer going somewhere else for his or her business and having distrust in the industry. Although this chapter is not intended to prepare you fully

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for a position as a service writer, it is very important to understand the role and communication of one. Remember, when you are a technician, you represent not only your own professionalism and abilities, but also the repair facility you work for, and the entire industry as a whole.

PROPER VEHICLE CARE What are the most expensive objects you own? Most people would say their home or their vehicle. When a customer hands you their keys they are trusting you with their vehicle. Make sure to have clean hands and clothes. Before test-driving the vehicle, do a quick walkaround inspection, checking for: ■■ Tire, light lenses, windshield, and wiper condition ■■ Oil and brake fluid level ■■ Up-to-date plates and a valid inspection decal ■■ Scratches or damage: point any out to the customer and/or take pictures If you find anything, document it on the repair order. Make sure you use a seat, ­steering cover, and floor mat before test-driving (Figure 3-1). While working on the vehicle in the shop: ■■ Watch out for hitting lift posts or other equipment with the doors. ■■ Use fender covers. After repairs: ■■ Clean up any fluid, grease, or fingerprints on the vehicle. ■■ Test-drive the vehicle (if necessary) to confirm the repair. ■■ Roll windows up, lock doors, and record mileage on the repair order.

4 3 2

5

6 7

8

60 6 4 40 20 0

80

100 00 110 0 12 20 120

1

2

3 4

5 6

Figure 3-1  To protect your customer’s property, use seat and steering ­covers and a floor mat before test-driving any vehicle.

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WRITING A SERVICE REPAIR ORDER Writing a service repair order is one of the most important steps of repairing any vehicle. It is always the first step, and it involves good communication with the customer and allows the technician to clearly analyze and focus on repairing what the vehicle actually came in for. A service repair order is a recorded document that is used for legal, tax, and general recording purposes. Other names for a service repair order are a service record, work order, or repair order (RO). Repair orders are commonly kept on a computer and can be distributed to the technician electronically. If written on paper a copy will be given to the technician. It is the service writer’s job to properly communicate with the customer and write down as much related information as possible on it. The service writer may also be the responsible person for providing an estimate and completing the money transaction of the sale. The service writer may also need to translate the customer’s perception of the problem and ask key questions. For example, the customer may state that the engine makes a loud ticking noise. If this is what is actually written on the repair order for the technician to read, then the technician will be spending a lot of time looking for that problem. And when the technician finds something wrong, it may or may not be what the customer is actually complaining about. If the technician is not given clear instructions or the ability to talk directly to the customer, the inspection will be of lower quality. The service writer needs to be able to translate and identify this from the customer and ask key questions, such as “When does the noise occur?”, “How loud is it?”, “Do you hear it when you are accelerating or during any other type of driving?”, “Does the noise go away or get louder as you drive?”, and other questions. If the repair order does not clearly state the concern, a misdiagnosis may occur. This could cost the repair facility money, customer trust, and their reputation. The repair order also contains vital information such as the labor rate, parts cost, estimate of total cost, when the vehicle will be ready, any upcoming services needed or additional ­concerns found, the VIN, year, make, model, license plate number, and the mileage. It is important to check the vehicle information for accuracy just as you bring the vehicle into the shop. The last thing that anyone needs is to get things mixed up and repair the wrong vehicle. The most important part of the repair order is that it communicates the 3Cs: concern, cause, and correction. The concern is what the customer says is wrong with the vehicle. The technician diagnoses the vehicle and completes the “cause” section. This section should be detailed, clean, and well written. The correction is the list of parts and the labor performed that describes how the vehicle was repaired. The technician may in some cases have to talk to the customer to obtain more ­information to find the source of the problem. The technician, the service writer, and the service manager may have to work together using their experiences, the service manual, and online resources to find the cause of the problem. The repair order is a legal document. Make sure that everything is written clearly and correctly.

A repair order is a ­written legal ­document that describes the concern (customer complaint), the cause (what needs repair or what is wrong), and the ­correction that has been made.

The “3Cs”—concern, cause, and correction— should be noted on the repair order.

TEST-DRIVING FOR ENGINE CONCERNS It is often difficult to test-drive a vehicle that has an engine problem. The engine may not start at all, it may not be able to get up to speed, or it may make so much noise that it is simply not safe at all to drive it on the road. Each of these situations may not require a test-drive to determine the problem. But if the engine noise or problem is less severe than that, you may need a test-drive. During the test-drive, a technician must be aware of everything. Your senses should be heightened during this procedure. Turn off the radio and pay attention. First try looking at the big picture. Looking at the overall condition of the vehicle may give you clues

This car has a flood title. It may look normal from the outside, but the engine has a lot of water damage.

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to the age of the engine. Watching the tailpipe for smoke may also give you clues to what problems you may be experiencing (Figure 3-2). During the test-drive, you may experience a problem that is not engine mechanically related. Maybe you believe the problem is related to the transmission, engine computer, or fuel system. In these cases, you may want to bring a technician who specializes in engine performance diagnostics with you. You may also want to bring a scan tool with you to watch and record data (Figure 3-3). Also use common sense when test-driving

Figure 3-2  A lot of thick blue smoke may indicate major engine repairs.

Figure 3-3  It may be helpful to use a scan tool during the test-drive. Always pay attention to the road, and use the recording function of the tool. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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a vehicle, and never watch the scan tool while trying to drive. Most scan tools have a flight recording option, so you can look at the data when you return to the shop. The test-drive should last as long as you need to verify the complaint and determine any related symptoms. Some engine problems occur only at a certain temperature. Some noises are heard only when the engine is cold but go away when the engine warms up. Piston slap, a common noise that is not always a problem, is a noise that goes away when the engine warms up. And the opposite is true. Some engine parts will make more noise and have problems as the engine warms up. When the engine warms up, several things happen. The oil gets thinner, the metals start to expand, and the gaskets are stressed.

IDENTIFYING THE AREA OF CONCERN There are typically more than 20,000 parts on the vehicle that at some time may need replacing due to damage or wear. It is your job as a technician to understand how they work individually and together in a system in order to best be able to diagnose related problems. To do this, you must be able to focus on one area of the vehicle. In engine repair and rebuilding, you must first be able to focus under the hood. Often an engine will have had problems for a period of time before you see the vehicle. The customer may not have noticed any problems at the time it started. When asking the customer what is wrong with his or her car, be sure that you understand the customer clearly. If language is an issue, get an assistant to help with communication. Being able to communicate with a customer in technical terms proves to be the most challenging of all tasks. When trying to explain something or communicate with a customer, you should avoid using very technical terms and use clear everyday terms. Avoid using very general terms, like “that thing,” as they may make the customer feel very inferior or substandard. Some customers will understand the word “piston” and be able to relate it as an engine component, but they may not know what one looks like or what it does. You will have to be the judge of your actions when you are trying to understand what it is the customer needs. When focusing on one area, try to ask as many questions as possible. Make sure to get a phone number where the customer can be reached quickly. If you are still trying to establish the vehicle’s problem area with the customer, try test-driving the vehicle with the customer. Ask the customer to drive the vehicle and attempt to repeat the problem. Sometimes this may be difficult, but remember to be patient and calm (Figure 3-4). Once you have determined the area to focus on, attempt to narrow down your search by determining the conditions at which the problem occurs and just as importantly, when they don’t. An example of this is when the customer has an engine noise, but it makes noise only when you accelerate hard from a dead stop. At times we may notice a concern on our test-drive such as a noise that can be a result of the problem, but that is not the cause. To continue with our example, we may have isolated the noise to the engine but then find the cause to actually be due to a collapsed engine mount, not the engine itself. Sometimes using a chassis ear machine (Figure 3-5) works well when trying to figure out where the noises are coming from. You can attach the ends of the chassis ear to components on the engine and then bring the wires into the passenger compartment and listen to them while driving. The chassis ear is designed for listening to suspension, steering, and chassis problems but can be used for engines as well. Be careful when using this tool because you don’t want to hear suspension or steering problems and assume they are engine problems. Make sure to fully read the directions with the chassis ear.

A chassis ear machine uses several small microphones that can be placed under the hood and then routed to the passenger compartment where the driver can use a set of headphones.

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Figure 3-4  Sometimes a test-drive with the customer is necessary.

Figure 3-5  A chassis ear is a good tool to help focus on one area.

Once you have found the problem area of the engine, ask the customer about the car’s past service history. If there have been other major problems like a head gasket wear, overheating, or oil pressure problems in the past, then ask what repairs have been completed. When writing up a repair order it is good practice to ask when and where previous repairs have been done. The customer may have the old receipts and repair orders from

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Basic Testing, Initial Inspection, and Service Procedures

Figure 3-6  This car has a flood title. It may look normal from the outside, but the engine has a lot of water damage.

other shops. These are all clues to the puzzle. If things are not adding up, try asking the owner if the vehicle has been in an accident, or has a salvage or flood title. Many flood and salvage vehicles have preexisting damage that has never been fully repaired. The body and exterior may be in great shape, but the engine may have suffered damage and never received the proper repairs (Figure 3-6). AUTHOR’S NOTE  Early in my career as a technician, I was preparing to perform a timing belt service on a car. I grabbed the repair order and found the keys hanging up on the key board with all the other vehicle keys. The key wasn’t labeled, so I guessed at which one to grab. I went out to the parking lot, found the car, and drove it into the shop. I put it up on the hoist and continued with my repair. Once I was finished with the repair, I test-drove it and then wrote down the “mileage out” on the repair order (some repair orders track the mileage that the repair facility put on the car). I noticed that there must have been a mistake made by the service writer typing in the mileage since it looked like I put on close to 40,000 miles on my test-drive. When I stepped out of the vehicle, I checked the license plate, and the plate number was different than the one on the repair order. I went to the service writer, and he mentioned that there were two cars in the lot today and they were the same car, same color, and so on. The only things that were different were the mileage, license plate, and the work they were in for. After realizing that I made the mistake of grabbing the wrong keys and not verifying the correct vehicle, I pulled the wrong vehicle back into the shop and started to remove the timing belt. The customer came by, and I explained the mistake I made. She stopped me right there and said, “My car needed the timing belt replaced soon anyway. Leave the belt on.”

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CASE STUDY A close relative of mine had recently brought her van into a service center because the “service engine soon” light was on and the engine was running rough. The service center called her back a few hours later and told her that the repair would cost around $1,400 and that most of the computer parts, ignition parts, and fuel system parts had gone bad, all at once. The work was authorized, and the parts were installed. After all of the parts were installed, the engine still ran rough and the light was still illuminated. After complaining to the service manager, a technician found that a simple diagnostic step was skipped. After performing this easy step, the technician found a broken valve spring. The customer was very disappointed, as well as was the service manager. Often technicians get wrapped up in looking at the most complicated systems and components as the problem and forget to perform the basic tests. This situation could have gone smoother and cost the customer much less if there was better communication and the correct steps were taken in the first place.

ASE-STYLE REVIEW QUESTIONS 1. Some of the vital information on the repair order are: A. The VIN B. The mileage C. The year, make, model D. All of the above 2. The repair order may also be called: C. Both A and B A. A work order B. A service record D. Neither A nor B 3. The test-drive: A. Allows a technician to always try driving ­different vehicles B. Can be useful when diagnosing engine problems C. Should always be short D. Is not important 4. The service writer needs to: A. Communicate with the technician and the customer B. Have a clear understanding of what the ­customer’s concern is C. Explain to the customer the work that is to be performed D. All of the above

5. Technician A says that writing the repair order is usually the first step in repairing a vehicle. Technician B says that the repair order is a legal document. Who is correct? A. A only B. B only

C. Both A and B D. Neither A nor B

6. Technician A says that the technician will complete the “cause” section of the repair order. Technician B says that the technician may have to communicate with the customer to find the problem. Who is correct? A. A only B. B only

C. Both A and B D. Neither A nor B

7. Who might the technician need to work with to find the cause of a problem? A. The service writer B. The customer C. The service manager D. All of the above

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Basic Testing, Initial Inspection, and Service Procedures

8. The “cause” section of the repair order contains: A. The parts and labor cost for repairing the vehicle B. The amount of sales tax the customer should be charged C. The reason the vehicle came into the repair facility D. The technician’s diagnosis

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10. A misdiagnosis may occur if the: A. Repair order is not clearly written B. Year, make, or model is incorrect C. Technician is not able to focus in on the area of concern D. All of the above

9. Technician A says that basic testing can include the use of a scan tool. Technician B says that basic testing can include a chassis ear machine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. The service writer’s duties are being discussed. Technician A says that the service writer may be the one who provides the repair estimate for the customer. Technician B says that the service writer usually completes the repair order. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that the service writer initiates the repair order. Technician B says that the technician initiates the repair order. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Technician A says that the repair order is a legal document. Technician B says that the repair order should be used as a communication tool with the customer. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. In order, the “3Cs” of a repair order are: A. Cause, compile, correct B. Cause, concern, correction C. Concern, cause, correction D. Correct, cause, compile

3. When diagnosing an engine concern, it is usually best to: A. Focus on one area B. Communicate the concern on the repair order with the service writer after the problem was found C. Both A and B D. Neither A nor B

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Basic Testing, Initial Inspection, and Service Procedures

Name ______________________________________

Date __________________

ENGINE COMPONENT IDENTIFICATION Upon completion of this job sheet, you should be able to properly identify several engine components and their basic functions. Tools and Materials • Engine components Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Your instructor will provide you with a variety of engine components. Write down the name of each one, and describe one function of each. 1. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 2. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 3. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 4. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 5. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 6. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 7. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________

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8. Name of component _______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 9. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 10. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ 11. Name of component ______________________________________________________ Function _________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date __________________

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JOB SHEET

15

TEST-DRIVE, BASIC INSPECTION, AND PREPARING FOR SERVICE Upon completion of this job sheet, you should be able to properly prepare a vehicle for servicing, perform a basic engine and vehicle inspection, and understand how to perform a test-drive for engine concerns. NATEF Correlation This job sheet addresses the following RST tasks: Preparing Vehicle for Service, Task #2 Identify purpose and demonstrate proper use of fender covers, mats. Preparing Vehicle for Customer, Task #1 Ensure vehicle is prepared to return to customer per school/company policy (floor mats, steering wheel cover, etc.). Tools and Materials • Vehicle • Floor mat • Steering wheel cover • Seat cover Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Complete the job sheet using the vehicle chosen. Consult your instructor before you are ready to perform a test-drive. 1. If there is a customer complaint, list it here. Otherwise, refer to a service repair order with the vehicle history and customer concern. _________________________________________________________________________ 2. Before entering the vehicle, place a floor mat, steering wheel cover, and seat cover in the vehicle.

h

3. Before going on a test-drive, open the hood and start the engine. Describe how the engine sounds (good, idles rough, makes noises, etc.) _________________________________________________________________________ _________________________________________________________________________ 4. Is any excessive smoke coming from the exhaust tailpipe? _________________________ 5. Turn the engine off, and check the major fluid levels, such as the oil and coolant. Describe your findings. _________________________________________________________________________ _________________________________________________________________________ 6. Perform a quick inspection of the vehicle to make sure that it is roadworthy for a test-drive.

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7. During your test-drive you should simulate the problem and make note of what happens during the test-drive.

Task Completed h

8. After your test-drive has been completed, write down your findings. Were you able to repeat the customer’s concern? If yes, describe what problems you found during the test-drive. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

Caution Do not attempt to write when driving. Always follow all traffic laws and drive safely.

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date __________________

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16

WRITING A SERVICE REPAIR ORDER Upon completion of this job sheet, you should be able to properly write and complete a ­service order. NATEF Correlation This job sheet addresses the following RST task: Preparing Vehicle for Service, Task #1 Identify information needed and the service requested on a repair order. Preparing Vehicle for Service, Task #3 Demonstrate use of the three Cs (concern, cause, and correction). Preparing Vehicle for Service, Task #4 Review vehicle service history. Preparing Vehicle for Service, Task #5 Complete work order to include customer information, vehicle identifying information, customer concern, related service history, cause, and correction. NATEF Correlation This job sheet addresses the following MLR task for Engine Repair: A.1. Research applicable vehicle and service information, vehicle service history, service precautions, and technical service bulletins. This job sheet addresses the following AST/MAST tasks for Engine Repair: A.1. Complete work order to include customer information, vehicle identifying information, customer concern, related service history, cause, and correction. A.2. Research applicable vehicle and service information, including fluid type, internal engine operation, vehicle service history, service precautions, and technical service bulletins. Tools and Materials • Vehicle • Service repair work order or specialized computer software program Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will assign a vehicle to you. Complete the job sheet using that vehicle by completing a repair order. If one is not available, use the generic form in this job sheet. 1. Complete the customer information section. This should include the name, address, contact numbers, and the best time available to call.

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2. Complete the vehicle information. This should include the year, make, model, VIN, mileage, engine type and size, and any other related information.

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3. Briefly inspect the vehicle for previously existing body or engine damage. Mark any findings on repair order in the notes section.

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4. Ask the customer (or the instructor) what the concern for bringing the vehicle in is.

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Task Completed 5. Ask the customer (or the instructor) if there is any previous work or history related to this concern.

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6. Ask the customer (or the instructor) what the cause of the problem is. Write this down.

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7. Ask your instructor to add diagnostic time, parts, and labor to the repair order. This is the correction to the vehicle.

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8. Complete the repair order by adding the parts and labor and adding tax.

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Basic Testing, Initial Inspection, and Service Procedures Customer Information Name:

Phone:

Address:

Best time to contact:

Date/time received:

Date/time promised:

Vehicle Information Year:

Model:

Make:

VIN:

License:

Engine:

Mileage:

Notes: Customer Concern

Previous Repairs Completed (Vehicle History)

Diagnosis of Problem (Cause)

Repairs Made to Vehicle (Correction) Part #

Total Parts

Amount

Total Tax

Labor Item

Sales Tax

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Amount

Total Due

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CHAPTER 4

DIAGNOSING AND SERVICING ENGINE OPERATING SYSTEMS

Upon completion and review of this chapter, you should understand and be able to describe: ■■

■■

■■

■■ ■■ ■■ ■■ ■■

■■ ■■

■■ ■■

How properly to diagnose customer complaints associated with engine operation. How properly to perform an open circuit test on the battery and to ­accurately interpret the results. How to test the capacity of the battery to deliver both current and voltage and to accurately interpret the results. How to perform a battery conductance test. How to perform a systematic diagnosis of the starting system. How to determine what can cause slow crank and no-crank conditions. How to determine if a slow or no-­crank condition is engine related. How to perform a quick-check test series to determine the problem areas in the starting system. How to remove and reinstall a starter motor. How to inspect engine assembly for fuel, oil, coolant, and other leaks, and determine necessary action. How to perform an oil and filter change. How to perform oil pressure tests and accurately interpret the results.

■■

■■ ■■

■■ ■■

■■

■■ ■■

■■ ■■ ■■

How to inspect oil pump gears or rotors and other internal components, and repair as needed. How to inspect auxiliary oil coolers, and replace as needed.

Basic Tools Basic mechanic’s tool set Service information

How to test coolant; drain, flush, and refill coolant; and bleed as required. How to diagnose customer concerns associated with the cooling system. How to perform cooling system, cap, and recovery system diagnostic tests. How to inspect and replace cooling system hoses, thermostat, water pump, and radiator. How to inspect and test cooling fans, shrouds, and dams. How to inspect, test, and replace oil temperature and pressure switches and sensors. How to inspect, replace, and adjust drive belts, tensioners, and pulleys. How to connect a scan tool to an OBD II vehicle and check for DTCs. How to interpret some of the data stream from an OBD II vehicle’s PCM.

Terms To Know Aluminum hydroxide deposits Battery terminal voltage drop test Bearing Blowby Capacity (load) test Conductance test

Current draw test Electrolysis Flex fans Hydrostatic lock Jet valves Oil pressure test Oil pump

Open circuit voltage test Pickup tube Positive crankcase ventilation (PCV) system Radiator Relief valve Starter quick test

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INTRODUCTION The engine’s operating systems provide the means for starting the engine and keeping the engine running, and provide longevity for the engine. These systems require periodic maintenance to ensure proper operation. Proper diagnosis of the operating systems can prevent costly failures in the engine. The battery, starting system, cooling system, lubrication system, and fuel and ignition systems must be operating properly for the engine to perform as designed. Before diagnosing an engine mechanical problem, you must be sure that an engine support system is not causing engine performance symptoms. Proper maintenance of these systems is important to engine longevity and customer satisfaction. In addition, if the engine is being rebuilt, prior to assembling the engine, it is very important to make sure the lubrication and cooling systems are inspected and any faulty components are replaced or repaired. Neglecting to repair problems in this area can lead to early failure of the engine. Many of the inspection and test procedures used during engine rebuilding can be used to diagnose and repair the systems with the engine still in the vehicle. When rebuilding an engine, many of the lubrication and cooling system components are replaced as a common practice. The remaining components must be cleaned and inspected before returning them to service.

BATTERY SAFETY Understanding batteries is important, but you must first understand how to handle them safely. There are many types of batteries that can be used in vehicles, but the most common type of battery used is the 12-volt lead-acid type. These batteries have metal plates inside that are made of lead and lead dioxide. To have the chemical reaction needed to produce electricity, an electrolyte acid is used. The acid inside a battery can be unsafe if not handled properly. You must take care not to spill the battery, turn it upside down, or overcharge it. A charging battery will emit hydrogen gas from its vents. This gas is explosive, so keep any sparks away from it. You should also not charge or jump-start a battery that is frozen. A battery will freeze when it becomes discharged and cold. Charging a frozen battery could cause it to explode. When handling a battery, you should also take care not to touch the acid with your skin. Wear the proper safety equipment, such as gloves. Acid will irritate your skin, and it can cause holes in your clothing. You also need to be aware of the high-voltage batteries in hybrid and electric vehicles. These batteries have a charge level on them that could be lethal. More information about hybrid and electric battery safety is covered in Chapter 14.

BATTERY TESTING

Classroom Manual Chapter 4, page 62

Special Tools Fender covers Safety glasses

Because of its importance, the battery should be checked whenever the vehicle is brought into the shop for service. A faulty battery can cause engine performance problems, cause engine starting problems, or leave a customer stranded. Checking the battery regularly can save diagnostic time and prevent vehicle breakdowns. By performing a battery test series, it can be determined if the battery is good, in need of recharging, or must be replaced. There are many different manufacturers of test equipment designed for testing the battery (Figure 4-1). Always follow the procedures given by the manufacturer of the equipment you are using.

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Figure 4-1  This volt-ampere tester (VAT) can test the capacity of the ­battery, starting and charging system.

Battery Inspection Before performing any electrical tests, the battery should be inspected, along with the cables and terminals. The complete visual inspection of the battery will include the following items: 1. Battery date code. This provides information as to the age of the battery. 2. Condition of battery case. Check for dirt, grease, and electrolyte condensation. Any of these contaminants can create an electrical path between the terminals and cause the battery to drain. Also check for damaged or missing vent caps and cracks in the case. A cracked or buckled case could be caused by excessive tightening of the holddown fixture, excessive under-hood temperatures, buckled plates from extended overcharged conditions, freezing, or excessive charge rate. 3. Electrolyte level, color, and odor. If necessary, add distilled water to fill to 1/2 inch above the top of the plates. After adding water, charge the battery before performing any tests. Discoloration of electrolyte and the presence of a rotten egg odor indicate an excessive charge rate, excessive deep cycling, impurities in the electrolyte solution, or an old battery. 4. Condition of battery cables and terminals. Check for corrosion, broken clamps, frayed cables, and loose terminals (Figure 4-2). 5. Battery abuse. This includes the use of bungee cords and two-by-fours for holddown fixtures, too small a battery rating for the application, and obvious neglect to periodic maintenance. In addition, inspect the terminals for indications that they have been hit upon by a hammer and for improper cable removal procedures; also check for proper cable length. 6. Battery tray and holddown fixture. Check for proper tightness. Also check for signs of acid corrosion of the tray and holddown unit. Replace as needed. 7. If the battery has a built-in hydrometer, check its color indicator (Figure 4-3). Green indicates the battery has a sufficient charge, black indicates the battery requires charging before testing, clear indicates low electrolyte level, and yellow indicates the battery should be replaced.

Special Tools Safety glasses Voltmeter Terminal pliers Terminal puller Terminal and clamp cleaner Fender covers

WARNING  Do not attempt to pry the caps off of a maintenance-free battery; this can ruin the case. You cannot check the electrolyte level or condition on maintenance-free batteries. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-2  These battery connections could easily cause a no-start condition.

Green dot

Dark

Clear

Top of battery Sight glass

Clear plastic rod

Green ball 65 percent or above state of charge

Below 65 percent state of charge

Low-level electrolyte

Figure 4-3  A built-in hydrometer indicates the battery state of charge.

A battery can be tested in many ways. A conductance test sends a low current AC signal into the battery and the return signal is analyzed. A capacity (load) test draws energy from the battery and measures the amount of voltage drop.

WARNING  Always wear safety glasses when working around a battery. Electrolyte can cause severe burns and permanent damage to the eye.

A conductance test sends a low-current AC signal into the battery. The return signal is then analyzed. A capacity (load) test uses a carbon pile to draw energy out of the battery. The voltage level of the battery should not drop below 9.6 volts during the test. When the battery and cables have been completely inspected and any problems ­corrected, the battery is ready to be tested further. For many of the tests to be accurate, the battery must be fully charged.

BATTERY TESTING SERIES Battery Conductance Test.  A newer method of testing a battery is called a conductance test. A conductance tester will test the battery’s ability to conduct electricity (Figure 4-4). This is a good indicator of a battery’s health and whether it will be able to provide adequate service when installed in the vehicle. A conductance test is considered to be more accurate Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Figure 4-4  This type of tester will test the conductance of the battery. It is quick and can usually be done in less than a minute.

139

Figure 4-5  This Midtronics tester is becoming an industry standard.

than the previous method of testing batteries. During a conductance test, the tester will send a low-current AC signal into the battery. The return signal that is generated is then analyzed. Some conductance battery testers also include a battery charger. These types of testers can recharge a battery if it is not ready to be tested accurately (Figure 4-5). During recharging, the tester can measure key items that will indicate if the battery will be strong enough to hold a good charge when it is done. SERVICE TIP  Grid growth can cause the battery plate to short out the cell. If there is normal electrolyte level in all cells but one, that cell is probably shorted.

Battery Terminal Voltage Drop Test.  The battery terminal voltage drop test is a simple test that will establish the condition of the terminal connection. It is a good practice to perform this test anytime the battery cables are cleaned or disconnected and reconnected to the terminals. By performing this test, comebacks due to loose or faulty connections can be reduced. Set your digital multimeter (DMM) to DC volts. Connect the negative test lead to the cable clamp, and connect the positive meter lead to the battery terminal. Disable the ignition system to prevent the vehicle from starting. This may be done by removing the ignition coil primary wires (Figure 4-6). (You can also remove the ignition system fuse, PCM fuse, or fuel pump fuse.) On vehicles with distributorless ignition, disconnect the coil primary wires (these are the small gauge wires connected to the coils). Crank the engine and observe the voltmeter reading. If the voltmeter shows over 0.5 volt, there is a high resistance at the cable connection. Remove the battery cable using the terminal puller (Figure 4-7). Clean the cable ends and battery terminals or replace as needed (Figure 4-8).

Battery State of Charge The battery’s state of charge (SOC) should be determined prior to performing a battery capacity test. The SOC can be determined by checking each cell’s specific gravity, averaging the cells, and comparing the reading to a chart (Figure 4-9). Specific gravity can be measured with a hydrometer or a refractometer. (See Photo Sequence 9, Cooling System Testing P9-3 and P9-4, and Figure 4-27.) Most hydrometer readings must be ­temperature-adjusted; refractometers readings do not need adjustment.

The battery terminal voltage drop test checks for poor ­electrical connections between the battery cables and terminals.

Special Tools Digital multimeter Refractometer Hydrometer Fender covers Safety glasses

Caution Always refer to the manufacturer’s service manual for the correct procedure for disabling the ignition system. Using the wrong procedure cam damage ignition components.

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Figure 4-6  Disconnecting the coil primary connections to prevent the engine from starting and to protect the coil.

Figure 4-7  Use battery terminal pullers to remove the clamp from the ­battery post. Do not pry the clamp.

100%

75%

1.230

50%

1.200

1.170

State of charge

Specific gravity

1.260

25%

1.140 0% 12.00

12.20

12.40

12.60

Open circuit voltage

Figure 4-8  The terminal cleaning tool is used to clean the clamp and the terminal.

The open circuit ­voltage test is used to determine the battery’s state of charge.

If a cell difference of 50 points (.050) or greater is found when checking a ­battery’s specific gravity, the battery will need replacement.

Figure 4-9  Open circuit voltage test results relate to the specific gravity of the battery cells.

On a sealed or maintenance-free battery, the individual cells cannot be accessed, ­making the open circuit voltage test the only option to check SOC.

Open Circuit Voltage Test.  To obtain accurate test results, the battery must be stabilized. If the battery has just been recharged, perform the capacity test and then wait at least 10 minutes to allow battery voltage to stabilize. Connect a voltmeter across the battery terminals, observing polarity (Figure 4-10). Measure the open circuit voltage, taking the reading to the 0.1 volt. To analyze the open circuit voltage test results, consider that a battery at a temperature of 808F (268C), in good condition, should show at least 12.45 volts (Figure 4-11). If the state of charge is 75 percent or more, the battery is considered charged and then can be load tested (Figure 4-9). Battery Capacity Test.  A capacity test (also known as a load test) is still a valid battery test, but it has been proven to be less accurate in determining if a battery will provide good service. A carbon pile tester is now used to perform this test (Figure 4-12).

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

141

Figure 4-10  Open circuit voltage test using a DMM.

Open Circuit Voltage

State of Charge (%)

12.6 or greater

100

12.4–12.6

70–100

12.2–12.4

50–70

12.0–12.2

25–50

0.0–12.0

0–25

Figure 4-11  The results of the open circuit voltage test indicate the state of charge.

Figure 4-12  This is a VAT (volt-ampere tester) machine. It contains a carbon pile in the backside and can perform a capacity (load) test.

Many types and brands of testers are available, but all of them have a voltmeter and an ammeter. A load test machine works by connecting the high-current clamps of the tester to the battery terminals and the inductive pickup lead (amp clamp) to the negative tester cable. The battery must be fully charged before performing the test. For best results, the battery electrolyte should be close to 808F (26.78C). The tester then draws half of the battery’s CCA rating from the battery for 15 seconds. On some testers this is done automatically, and on others there is a control knob for the amperage. If the voltmeter does not drop below 9.6 volts during the 15-second test, then the battery passes the load test. Battery Case Test.  A dirty battery can allow voltage to leak across the top of the battery and cause discharging. To test a battery for this condition, place the positive voltmeter lead on a battery post. Place the negative lead at spots across the top of the battery. Repeat the test on the other battery post. Any voltage reading present indicates that the battery is dirty and allowing discharging. Clean the top of the battery with a mixture of baking soda and water or use a battery cleaning solvent. Retest to verify your repair.

Special Tools VAT tester Safety glasses Fender covers

Absorbed Glass Mat (AGM) Battery Precautions An AGM battery is a lead-acid battery that is sealed using special pressure valves (Figure 4-13). This is truly a maintenance-free battery that cannot and should never be opened. Overcharging is especially harmful to AGM batteries and can shorten their service life. You should use a good battery charger that does not allow more than 16 volts, usually the manufacturer of the battery or the dealership will have a special charger. A conductance tester is the only type of tester that will work on AGM batteries. Select AGM type battery on the testers menu. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-13  AGM (Absorbed Glass Mat) batteries have to be tested using a conductance tester.

STARTING SYSTEM TESTS AND SERVICE The starter motor must be capable of rotating the engine fast enough so that it can start and run under its own power. The starting system is a combination of mechanical and electrical parts working together to start the engine. The starting system includes the following components:

Special Tools Battery charger Voltmeter Safety glasses Fender covers

1. Battery 2. Cable and wires 3. Ignition switch 4. Starter solenoid or relay 5. Starter motor 6. Starter drive and flywheel ring gear 7. Starting safety switch

Starting System Troubleshooting Caution Some engines turn counterclockwise as viewed from the front crankshaft ­pulley. These engines are rare, but damage may occur if they are turned the other way. Check the service manual for warnings or ask your instructor. Hydrostatic lock is the result of attempting to compress a liquid in the cylinder. Since liquid is not compressible, the piston is not able to travel in the cylinder.

Customer complaints concerning the starting system generally fall into four categories: no-crank, slow cranking, starter spins but does not turn engine, and excessive noise. As with any electrical system complaint, a systematic approach to diagnosing the starting system will make the task quicker and easier. First, the battery must be in good condition and fully charged. Perform a complete battery test series to confirm the battery’s condition. Many starting system complaints are actually attributable to battery problems. If the starting system tests are performed with a weak battery, the results can be misleading, and the conclusions reached may be erroneous and costly. Before performing any tests on the starting system, begin with a visual inspection of the circuit. Repair or replace any corroded or loose connections, frayed wires, or any other trouble sources. The battery terminals must be clean, and the starter motor must be properly grounded. The diagnostic chart shows a logical sequence to follow whenever a starting system complaint is made (Figure 4-14). The tests to be performed are determined by whether or not the starter will crank the engine. If the customer complains of a no-crank situation, attempt to rotate the engine by the crankshaft pulley nut. Rotate the crankshaft two full rotations, in a clockwise direction using a large socket wrench. If the engine does not rotate, it may be seized due to operating with lack of oil, hydrostatic lock, or broken engine components.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

143

Repair starter.

9.0 volts or more.

Check cranking voltage at starter “B” terminal.

Less than 0.5 volt.

Check voltage from engine block to battery negative post. Key in start position. Voltmeter positive lead on block.

Figure 4-14  Diagnostic chart used to determine starting system problems.

Clean and tighten positive battery cable terminals and/or replace cable.

Less than 9.0 volts.

Clean and tighten ground cable connection and/or replace cable.

0.5 volt or more.

Test battery. If OK, repair starter.

9.6 volts or more.

Check cranking voltage at battery.

Change battery, check for drain, and check generator.

Less than 9.6 volts.

Green eye showing.

Eye dark.

Check battery state-of-charge.

Lamps dim or go out.

Turn headlamps and dome lamp on. Turn key to start.

No cranking. No sound from solenoid.

Less than 9.6 volts.

Replace engine control switch.

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Repair purple wire from switch to starter.

9.6 volts or more.

Repair starter.

9.6 volts or more.

Check connections and voltage at “S” terminal or starter solenoid.

With automatic transmission.

Operates OK.

9.6 volts or more.

Check clutch switch connector. If OK, replace switch.

More than 9.6 volts on one terminal.

Check bulkhead connector, fusible link, and engine control switch connections.

Won’t operate.

Replace engine control switch.

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Less than 9.6 volts.

Less than 9.6 volts on both terminals.

Repair yellow feed wire from engine control switch.

Repair starter.

9.6 volts or more.

Check connections and voltage at solenoid “S” terminal.

More than 9.6 volts on both terminals.

Check voltage at Clutch safety switch (attached to clutch) - clutch depressed.

With manual transmission.

Turn on radio, heater, and turn signals.

Lamps stay bright.

Turn headlamps and dome lamp on. Turn key to start.

No cranking. No sound from solenoid.

144

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Replace engine control switch.

Repair purple wire from switch to starter.

Figure 4-14 (Continued)

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Less than 9.6 volts.

Replace switch.

Less than 9.6 volts.

9.6 volts or more.

Repair starter.

9.6 volts or more.

Check connections and voltage at “S” terminal or starter solenoid.

9.6 volts or more.

9.6 volts or more.

Check clutch switch connector. If OK, replace switch.

More than 9.6 volts on one terminal.

Replace engine control switch.

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Less than 9.6 volts.

Less than 9.6 volts on both terminals.

Repair yellow feed wire from engine control switch.

Repair starter.

9.6 volts or more.

Check connections and voltage at solenoid “S” terminal.

More than 9.6 volts on both terminals.

Check voltage at Clutch safety switch (attached to clutch) - clutch depressed.

Check bulkhead connector, fusible link, and engine control switch connections.

With automatic transmission.

Check voltage at neutral sense switch (on steering column near floor) with trans. in neutral or park.

Won’t operate.

Operates OK. With manual transmission.

Turn on radio, heater, and turn signals.

Lamps stay bright.

Turn headlamps and dome lamp on. Turn key to start.

No cranking. No sound from solenoid.

Repair purple wire from switch to starter.

9.6 volts or more.

Repair starter.

9.6 volts or more.

Less than 9.6 volts.

Replace switch.

Less than 9.6 volts.

Replace engine control switch.

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Check connections and voltage at “S” terminal or starter solenoid.

9.6 volts or more.

Check voltage at neutral sense switch (on steering column near floor) with trans. in neutral or park.

9.6 volts or more.

Check clutch switch connector. If OK, replace switch.

More than 9.6 volts on one terminal.

Replace engine control switch.

Less than 9.6 volts.

With key in start, check voltage at engine control switch solenoid terminal.

Less than 9.6 volts.

Less than 9.6 volts on both terminals.

Repair yellow feed wire from engine control switch.

Repair starter.

9.6 volts or more.

Check connections and voltage at solenoid “S” terminal.

More than 9.6 volts on both terminals.

Check voltage at Clutch safety switch (attached to clutch) - clutch depressed.

Check anti-theft system if equipped.

Check bulkhead connector, fusible link, and engine control switch connections.

With automatic transmission. Check anti-theft system if equipped.

Won’t operate.

Operates OK. With manual transmission.

Turn on radio, heater, and turn signals.

Lamps stay bright.

Turn headlamps and dome lamp on. Turn key to start.

No cranking. No sound from solenoid.

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145

Clean and tighten positive cable connections. If OK, replace cable.

Repair starter.

Figure 4-14 (Continued)

Less than 9 volts.

Clean and tighten connections at starter. Measure voltage at stud of terminal “B” of starter solenoid.

Less than 0.5 volt.

9 volts or more.

Repair ground cable and connections.

0.5 volt or more.

Replace battery.

Repair starter.

This procedure is designed for use on engine and batteries at room or normal operating temperatures. It also assumes there are no engine problems which would cause cranking problems. To use it under other conditions might result in misdiagnosis.

Not OK.

Charge and load test battery.

Measure voltage from the battery negative terminal to the engine block. Positive voltmeter lead on block. OK.

Less than 9.6 volts.

9.6 volts or more.

Measure cranking voltage at battery terminal posts.

Remove battery lead from distributor. Make all voltmeter readings with the key in the start position.

Check: Battery for green indicator eyeball. Visual condition of battery cables and connectors. Oil viscosity in cold weather. If battery needs charging: Make generator and battery drain check. Charge battery and recheck cranking. If trouble has not been found, continue.

Slow cranking. Solenoid clicks or chatters.

Less than 9 volts. Clean and tighten positive cable connections. If OK, replace cable.

Repair starter.

Clean and tighten connections at starter. Measure voltage at stud of terminal “B” of starter solenoid.

Less than 0.5 volts.

9 volts or more.

Repair ground cable and connections.

0.5 volts or more.

Replace battery.

Repair starter.

This procedure is designed for use on engine and batteries at room or normal operating temperatures. It also assumes there are no engine problems which would cause cranking problems. To use it under other conditions might result in misdiagnosis.

Not OK.

Charge and load test battery.

Measure voltage from the battery negative terminal to the engine block. Positive voltmeter lead on block.

OK.

Less than 9.6 volts.

9.6 volts or more.

Measure cranking voltage at battery terminal posts.

Remove battery lead from distributor on gas engines. Remove battery lead from engine shut off (ESO) solenoid on diesel engines. Make all voltmeter readings with the key in the start position.

Check: Battery for green indicator eyeball. Visual condition of battery cables and connectors. Oil viscosity in cold weather. If battery needs charging: Make generator and battery drain check. Charge battery and recheck cranking. If trouble has not been found, continue.

Slow cranking. Solenoid clicks or chatters.

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Chapter 4

Ignition switch

Battery

Cranking motor

Figure 4-15  Excessive wear, loose electrical connections, or ­excessive voltage drop in any of these areas can cause a slow crank or no-crank condition.

Special Tools Fender covers Battery cable puller The starter quick test will isolate the problem area, that is, if the starter motor, solenoid, or control circuit is at fault.

If the engine does not crank and the headlights do not come on, check the fusible link. Check the ignition switch and the safety starting switch for proper operation and adjustment.

A slow crank or no-crank complaint can be caused by several potential trouble areas in the circuit (Figure 4-15). Excessive voltage drops in these areas will cause the starter motor to operate slower than required to start the engine. The speed at which the starter motor rotates the engine is important to engine starting. If the speed is too slow, compression is lost and the air-fuel mixture draw is impeded. Most manufacturers require a speed of approximately 250 rpm during engine cranking. If the starter spins but the engine does not rotate, the most likely cause is a faulty starter drive. If the starter drive is at fault, the starter motor will have to be removed to install a new starter or drive mechanism. Before faulting the starter drive, also check the starter ring gear teeth for wear or damage, as well as for incorrect gear mesh of the ring gear and starter motor pinion gear. Most noises can be traced to the starter drive mechanism. The starter drive can be replaced as a separate component of the starter.

Testing the Starting System As with the battery testing series, the tests for the starting system are performed on the VAT. Since the starter performance and battery performance are so closely related, it is important that a full battery test series be done before trying to test the starter system. If the battery fails the load test and is fully charged, it must be replaced before doing any other tests. Starter Quick Testing.  If the starter does not turn the engine at all and the engine is in good mechanical condition, the starter quick test can be performed to locate the problem area. To perform this test, make sure the automatic transmission is in park or a manual transmission is in neutral, and set the parking brake. Turn on the headlights. Next, turn the ignition switch to the START position while observing the headlights. Three things can happen to the headlights during this test: 1. They will go out. 2. They will dim. 3. They will remain at the same brightness level.

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Diagnosing and Servicing Engine Operating Systems

If the lights go out completely, the most likely cause is a poor connection at one of the battery terminals. Check the battery cables for tight and clean connections. It will be necessary to remove the cable from the terminal and clean the cable clamp and battery terminals of all corrosion.

147

Special Tools Fender covers VAT Jumper wires

SERVICE TIP  If the starter windings are thrown, this is an indication of several different problems. The most common is that the driver is keeping the ignition switch in the START position too long after the engine has started. Other causes include the driver opening the throttle plates too wide while starting the engine, resulting in excessive armature speeds when the engine does start. Also the windings can be thrown because of excessive heat buildup in the motor. The motor is designed to operate for very short periods of time. If it is operated for longer than 15 seconds, heat begins to build up at a very fast rate. If the engine does not start after a 15-second crank, the starter motor needs to cool for about 2 minutes before attempting to start the engine again.

If the headlights dim when the ignition switch is turned to the START position, the battery may be discharged. Check the battery condition. If it is good, then there may be a mechanical condition in the engine preventing it from rotating. If the engine rotates when turning it with a socket wrench on the pulley nut, the starter motor may have internal damage. A bent starter armature, worn bearings, thrown armature windings, loose pole shoe screws, or any other worn component in the starter motor that will allow the armature to drag can cause a high current demand. A short in the starter electrical circuit could also be the cause. If the lights stay brightly lit and the starter makes no sound (listen for a deep clicking noise), there is an open in the circuit. The fault is in either the solenoid or the control circuit. To test the solenoid, bypass the solenoid by bridging the BAT and S terminals on the back of the solenoid. The B1 terminal is a large terminal on the solenoid with a heavy gauge wire coming from the battery. Also on the solenoid, the S terminal has a smaller gauge wire coming to it from the ignition switch or starter relay. Use heavy jumper cables to connect the two terminals. If the starter spins, the ignition switch, starter relay, or control circuit wiring is faulty. If the starter does not spin, either the starter motor or the solenoid, or both are faulty. WARNING  The starter will draw up to 400 amperes. The tool used to jump the terminals must be able to carry this high current, and it must have an insulated handle. A jumper cable that is too light may become extremely hot, resulting in burns to the technician’s hand.

Current Draw Test.  If the starter motor cranks the engine, the technician should perform the current draw test. The following procedure is used for the VAT tester: 1. Connect the large red and black test leads on the battery posts, observing polarity. 2. Zero the ammeter. 3. Connect the ampere inductive probe around the battery ground cable. If more than one ground cable is used, clamp the probe around all of them (Figure 4-16). 4. Make sure all loads are turned off (lights, radio, and so on). 5. Disable the ignition system to prevent the vehicle from starting. This may be done by removing the ignition coil secondary wire from the distributor cap and putting it to ground, by removing the ignition system fuse, fuel pump fuse, PCM fuse, or by disconnecting the primary wires from the coils of an EI system. 6. Crank the engine, and note the voltmeter reading. 7. Read the ammeter scale to determine the amount of current draw.

The current draw test measures the amount of current the starter draws when actuated. It determines the electrical and mechanical condition of the starting system.

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Figure 4-16  Connecting the VAT leads to ­perform the starter current draw test. Figure 4-17  This spark plug is fouled with coolant.

Caution Always refer to the manufacturer’s ­service manual for the correct procedure for disabling the ­ignition system. Using the wrong procedure may damage ignition components. The specification for current draw is the maximum allowable, and the specification for cranking voltage is the minimum allowable.

Caution Always refer to the manufacturer’s ­service manual for the correct procedure for disabling the ignition system. Using an improper procedure may damage ignition components.

After recording the readings from the current draw test, compare them with the manufacturer’s specifications. If specifications are not available, as a rule, correctly functioning systems will crank at 9.6 volts or higher. Amperage draw is dependent upon engine size. Most V8 engines have an ampere draw of about 200 amperes, six-cylinder engines about 150 amperes, and four-cylinder engines about 125 amperes. Higher-than-specified current draw test results indicate an impedance to rotation of the starter motor. This includes worn bushings, a mechanical blockage, internal starter motor damage, a short in the starter motor circuit, and excessively advanced ignition timing. Lower-than-normal current draw test results indicate excessive voltage drop in the circuit caused by a bad or dirty connection, a faulty solenoid, or worn brushes. If the current test results are high and the engine does not turn, the starter may not need replacement. Hydrostatic lock or engine seizure may have occurred. To check for this, you should put a socket and ratchet on the crankshaft pulley bolt and attempt to turn the engine over manually by hand. If the engine turns easily, it is most likely a problem with the starter. If the engine does not turn, it is an internal engine problem. To determine the type of internal problem, start by removing the spark plugs from the engine and attempt to turn the crankshaft again. If it starts to turn easier, look for coolant, fuel, or oil that might be coming out of the spark plug holes (Figure 4-17). These fluids may have gotten into the combustion chamber by a blown head gasket, leaking fuel injector, or a cracked cylinder head or block. If the engine does not turn and no fluids come out of the spark plug hole, the engine may be mechanically seized. Since the readings obtained from the current draw test were taken at the battery, these readings may not be an exact representation of the actual voltage at the starter motor. Voltage losses due to bad cables, connections, relays, or solenoids may diminish the amount of voltage to the starter. Before removing the starter from the vehicle, these should be tested.

Starter Motor Removal If the tests indicate that the starter motor must be removed, the first step is to disconnect the battery from the system. WARNING  Remove the negative battery cable. It is a good practice to wrap the cable clamp with tape or enclose it in a rubber hose to prevent accidental contact with the battery terminal. If the positive cable is removed first, the wrench may slip and make contact between the terminal and the ground. This action may overheat the wrench and burn the technician’s hand.

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Diagnosing and Servicing Engine Operating Systems

It may be necessary to place the vehicle on a lift to gain access to the starter motor. Before lifting the vehicle, disconnect all wires, fasteners, and so on that can be reached from the top of the engine compartment. Disconnect the wires leading to the solenoid terminals. To prevent confusion, it is a good practice to use pieces of tape to identify the different wires. WARNING  Check for proper lift pad-to-frame contact after the vehicle is a few inches above the ground. Shake the vehicle. If there are any unusual noises or movement of the vehicle, lower it and reset the pads. If the lift pads are not properly positioned on the specified vehicle lift points, the vehicle may slip off the lifts, resulting in technician injury and vehicle damage.

On some vehicles, it may be necessary to disconnect the exhaust system to be able to remove the starter motor. Spray the exhaust system fasteners with penetrating oil to assist in removal. Loosen the starter mounting bolts, and remove all but one. Support the starter motor, remove the remaining bolt, and then remove the starter motor.

149

Special Tools Fender covers Jumper cables

Caution Do not operate the starter motor for longer than 15 ­seconds. Allow the motor to cool between cranking attempts. Operating the starter for more than 15 seconds may overheat and damage starter motor components.

WARNING The starter motor is heavy. Make sure that it is secured before removing the last bolt. If the starting motor is not properly secured, it may drop suddenly, resulting in leg or foot injury.

To install the starter motor, reverse the procedure. Be sure all electrical connections are tight. If you are installing a new or remanufactured starter, remove any paint that may prevent a good ground connection. Be careful not to drop the starter. Make sure that it is supported properly. Refer to Photo Sequence 5 for the typical starter removal and reinstallation. Some General Motors’ starters use shims between the starter motor and the mounting pad (Figure 4-18). To check this clearance, insert a flat blade screwdriver into the access slot on the side of the drive housing. Pry the drive pinion gear into the engaged position. Use a piece of wire that is 0.020 in. in diameter to check the clearance between the gears (Figure 4-19).

Shim

Engine block

Starter motor

The shims are used to provide proper pinion-to-ring gear clearance.

0.508-mm (0.020-in.) wire gauge Pinion gear

A 0.015-in. shim will increase the clearance approximately 0.005 in. More than one shim may be required.

Figure 4-18  Shimming the starter to obtain the ­correct pinion-to-ring gear clearance.

Flywheel

Figure 4-19  Checking the clearance between the pinion gear and ring gear.

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PHOTO SEQUENCE 5

Starter R 1 R

P5-1  Disconnect the negative battery cable first to prevent electrical arcing.

P5-2  If necessary, raise the vehicle to gain access to the starter.

P5-3  Remove under-car protective covers as needed to access the starter wiring and ­mounting hardware.

P5-4  Disconnect the battery cable and the other wires from the starter.

P5-5  Loosen the starter attaching bolts, and then remove the starter.

P5-6  Bench test the old starter to confirm your diagnosis. Also test the new or remanufactured unit to be sure it functions properly.

P5-7  Work the new starter back into the proper position.

P5-8  Clean the fasteners and tighten each of them securely. The starter is often grounded through the mounting bolts.

P5-9  Do a professional job of reassembling each of the components that you had removed to reach the starter.

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PHOTO SEQUENCE 5 (CONTINUED)

P5-10  Reconnect the battery.

P5-11  Verify that the new starter operates properly and without excess noise by cranking the engine over a few times.

If the clearance between the two gears is excessive, the starter will produce a highpitched whine while the engine is being cranked. If the clearance is too small, the starter will make a high-pitched whine after the engine starts and the ignition switch is returned to the RUN position.

Classroom Manual Chapter 4, page 60

SERVICE TIP  The major cause of drive housing breakage is too small a clearance between the pinion and ring gears. It is always better to have a little more clearance than too small a clearance.

LUBRICATION SYSTEM TESTING AND SERVICE Oil Pressure Testing Proper oil pressure is essential to engine life. Oil pressure is dependent upon oil clearances and proper delivery. If the clearance between a journal and the bearing becomes excessive, pressure is lost. Not all low oil pressure conditions, however, are the result of bearing wear. Other causes include improper oil level, improper oil grade, and oil pump wear. Another common cause of low oil pressure is thinning oil as a result of excessive temperatures or gas dilution. If low oil pressure is suspected, begin by checking the oil level. Too low a level will cause the oil pump to aerate and lose volume. If the oil level is too high, it may be due to gasoline entering the crankcase as a result of a damaged fuel pump, ignition misfire, leaking injector, or engine flooding. If the oil level and condition are satisfactory, check oil pressure using an oil pressure gauge. To perform an oil pressure test, remove the oil pressure sending unit from the engine (Figure 4-20). Using the correct size adapters, connect the oil pressure gauge to the oil passage. Start the engine, and observe the gauge as the engine idles. Watch the gauge as the engine warms to note any excessive drops due to temperature. Increase the engine rpm to 2,000 while observing the gauge. Compare the test results with the manufacturers’ specifications. Manufacturers provide oil pressure specifications with the engine at normal operating temperature; be sure the engine is fully warmed up. After the test is complete, reinstall the oil pressure sending unit, start the engine, and confirm

Bearings are used to carry the loads created by rotational forces.

Oil pressure testing is used to determine the condition of the bearings and other internal engine components.

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Chapter 4

Figure 4-20  Remove the factory-equipped oil pressure sending unit to connect an oil pressure gauge.

Special Tools Oil pressure gauge Adapters The oil pump is a rotoror gear-type positive displacement pump used to take oil from the sump and deliver it to the oil galleries. The oil galleries direct the oil to the high-wear areas of the engine.

there are no leaks. When reinstalling the sending unit you need to use a thread sealant. Always use a liquid thread sealant on the sending unit, not a tape sealant. Tape sealant can break off and be circulated throughout the system as a solid, thus causing damage. No oil pressure indicates that the oil pump drive is broken, the pickup screen is plugged, the gallery plugs are leaking, or there is a hole in the pickup tube. Lower-thanspecified oil pressure indicates improper oil viscosity, a worn oil pump, a plugged oil pickup tube, a sticking or weak oil pressure relief valve, or worn bearings.

SERVICE TIP  A quick check of main bearing clearance can be performed on most engines by use of an oil pressure gauge. While observing the gauge, quickly rotate the throttle to the wide-open throttle position and allow it to snap shut. The high vacuum created under idle conditions will have a tendency to hold the crankshaft up against the main bearing oil discharge holes. This will keep the oil pressure high. When the throttle is snapped open and shut very quickly, the amount of vacuum is reduced, allowing the crankshaft to lower. If the main bearing clearances are excessive, a drop in oil pressure will occur.

It is possible to have oil pressure that is too high. This can be caused by a stuck-closed pressure relief valve, by a blockage in an oil gallery, added additives, incorrect viscosity, or contaminated oil.

Oil Pump Service Since the oil pump is so vital to proper engine operation, it is usually replaced along with the pickup tube and screen whenever it fails or when the engine is being rebuilt or replaced. The relatively low cost of an oil pump is considered cheap insurance by most technicians, so replacement is the general rule. However, there may be instances when the oil pump will have to be disassembled, inspected, and repaired. Proper inspection requires the oil pump to be disassembled and cleaned. Photo Sequence 6 is a typical procedure for disassembling and inspecting a rotor-type oil pump that is driven by the crankshaft. Disassembly procedures for gear-type oil pumps are very similar to that of rotor-type oil pumps. If the pump housing is not damaged, a pump rebuild kit containing new rotors or gears, a relief valve and spring, and seals may be available. Since the oil is delivered to the pump before it goes through the oil filter, the pump is subject to wear and damage as contaminated oil passes through it. The particles passing through the gears or rotors of the pump wear away the surface area, resulting in a Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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reduction of pump efficiency. If the particles are large enough, they may cause the metal of the rotor or gear surfaces to raise, resulting in pump seizure. In addition, these larger particles can force a wedge in the pump and cause it to lock up. When removing the oil pressure relief valve, note the direction of the valve in the housing. Before removing the gears or rotor, mark adjacent teeth so they can be indexed in the same location when reassembled. Some manufacturers provide index marks. After the oil pump has been disassembled and cleaned, it can be inspected. This usually requires a thorough visual inspection, measuring clearances, and measuring parts. Carefully inspect the drive shaft for the oil pump. If the corners are rounded or the slot is damaged, replace the shaft. Gear-type oil pumps also require end clearance checks (Figure 4-21). In addition, each gear’s clearance must be checked (Figure 4-22). Check gear clearance at several locations around each gear. If the clearance is greater than 0.005 in. (0.13 mm) in any location, replace the pump assembly. Always consult the manufacturer’s service information for proper specifications.

153

The relief valve is used to prevent excessive oil pressure.

PHOTO SEQUENCE 6

Typical Procedure for Disassembly and Inspection of Rotor-Type Oil Pump

P6-2  Remove the relief valve cap, relief valve, and spring. Note the direction the valve is installed into the oil pump housing for installation.

P6-3  Remove the oil pump cover screws, and then remove the cover.

P6-1  The tools required to perform this task include a micrometer, feeler gauge, straightedge, center punch, hammer, and appropriate service manual.

P6-4  If the rotors do not have index marks, use a center punch to mark the rotors for installation.

P6-5  Wash all parts in solvent.

P6-6  Visually inspect the housing and rotors for signs of wear or scoring. If the housing is scored, replace the entire pump assembly. The mating surfaces of the rotors should be smooth.

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PHOTO SEQUENCE 6 (CONTINUED)

P6-7  Place a straightedge across the pump cover surface and attempt to insert a 0.003in. (0.076-mm) feeler gauge under the straightedge. The cover should be replaced or machined if it is excessively warped.

P6-8  Use an outside micrometer to measure the diameter of the outer rotor. Compare the measurement with specifications.

P6-9  Use an outside micrometer to measure the thickness of the outer rotor. Compare the results with specifications.

P6-10  Place the rotors back into the oil pump housing, and measure the side clearance of the outer rotor. If the measurement is greater than specifications and the rotor outer diameter is correct, replace the pump housing.

P6-11  Use a feeler gauge to measure the clearance of the inner rotor by aligning one of its lobes with a lobe of the outer rotor. If the measurement is greater than specifications, replace both rotors.

P6-12  With the rotors installed, place a straightedge across the housing and use a feeler gauge to measure the distance between the rotors and the straightedge. If the clearance is excessive and the rotor thickness is within specifications, replace the pump assembly.

P6-13  Visually inspect the relief valve for indications of scoring. Light scoring may be removed using 400-grit emery cloth.

P6-14  Measure the relief valve spring free height and pressure. Compare the test results with specifications.

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Pump housing

Outer rotor

Figure 4-21  Use a straightedge and feeler gauge to ­measure clearance.

Figure 4-22  Gear-type oil pumps must have gear-to-housing clearances checked before reusing them.

CUSTOMER CARE  Oil pump damage resulting from contamination of the oil indicates poor maintenance. Inform the customer of the need for routine oil and filter changes according to the manufacturer’s recommendations.

When assembling the oil pump, make sure to align the index marks of the gears or rotors. The cover gasket maintains proper gear or rotor clearance. Use the appropriate thickness as supplied by the manufacturer. After the cover is installed, torque the bolts to the specified value. Improper torquing may result in cover warpage and low pump output. The pickup tube and the screen should be replaced whenever the oil pump is replaced or rebuilt. If the tube attaches to the oil pump, install the new tube using light taps from a hammer. Make sure the pickup tube is properly positioned to prevent interference with the oil pan or crankshaft. Bolt-on pickup tubes may use a rubber O-ring to seal them. Do not use a sealer in place of the O-ring. Lubricate the O-ring with engine oil prior to assembly; then alternately tighten the attaching bolts until the specified torque is obtained. Prime the oil pump before installing it by submerging it into a pan of clean engine oil and rotating the gears by hand. When the pump discharges a stream of oil, the pump is primed. If a gasket is installed between the pump and the engine block, check to make sure no holes or passages are blocked by the gasket material. Soak the gasket in oil to soften the material and allow for good compression. When installing the oil pump, make sure the drive shaft is properly seated, and torque the fasteners to the specified value.

Oil Jet Valves Some engines use jet valves to spray oil into the underside of the piston to cool the top of the piston. These valves must be inspected and cleaned before they are returned to service. The valve consists of a check ball, spring, and nozzle. Check the nozzle opening by inserting a small drill bit into the hole. Do the same for the oil intake. With the drill bit installed in the intake hole, the check ball should be able to be moved about 0.160 in. (4.0 mm). Finally, operation of the jet valve can be checked using air pressure set at 30 psi.

Classroom Manual Chapter 4, page 71

The pickup tube is used by the pump to deliver oil from the bottom of the oil pan. The bottom of the tube has a screen to filter larger contaminants.

Caution Installing the relief valve backward will result in no oil pressure. Jet valves are used by some manufacturers to direct a stream of oil to the underside of the piston head. Jet valves are common on turbocharged engines to keep the piston cool to prevent detonation and piston damage.

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Chapter 4 Jet nozzle Oil inlet orifice

Check ball

Check ball spring

Figure 4-23  Jet valves spray oil into the bottom of the piston for cooling.

Special Tools Feeler gauge set Micrometer Straightedge

At this pressure, the check ball should lift off its seat. If the nozzle is bent or damaged, replace the jet valve (Figure 4-23).

Lubrication System Maintenance Lubrication system maintenance consists of periodic oil and filter changes. The oil pan is equipped with a drain plug to remove the oil from the crankcase. The engine must be warmed up before draining the oil to be sure the oil has picked up all debris from the engine. The oil will also drain faster when it is warm. CUSTOMER CARE  Some customers feel they need to add additional treatments to their engine oil. A variety of aftermarket and manufacturer-supplied additives are available to remove carbon, improve ring sealing, loosen stuck valves, and so forth. Before using these additives, refer to the vehicle manufacturer’s warranty. Use of some of these additives may void the warranty.

Special Tools Oil filter wrench or socket

The oil filter usually threads to the engine block or adapter. A band-type wrench or special socket is used to remove the filter from the engine. A rubber seal is located at the top of the oil filter to seal between the filter and block. Sometimes this seal may come off the filter and remain on the block. Be sure to remove the seal from the block if this occurs. Failure to remove the oil seal will result in oil leaks. Before installing the new oil filter, lubricate the seal, and fill the filter with oil. Install the oil filter. Do not overtighten the filter. Turn the filter a three-quarter turn after the seal makes contact. If you are installing a metal oil filter, do not use the oil filter wrench to tighten the filter. Only hand pressure is required. If you are installing a cartridge-style oil filter, use a torque wrench to tighten it. When installing this type of filter, make absolutely sure that you properly seat the new oil filter and install any new O-rings that come with the filter. A cartridge-style oil filter that is not properly seated will be crushed when installing and tightening the filter cap. If low oil pressure is noticed just after an oil change, remove the oil filter and check the pin on the end of the filter to make sure it wasn’t damaged. See Photo Sequence 7 for the typical procedures for changing oil. While the vehicle is in the air, check its underside for fluid leaks and make a note on the repair order if you see problems. Also make a quick safety check of the exhaust, ­suspension, and driveline. This may be the only time a customer brings his vehicle in for routine maintenance; the customer will appreciate your finding problems so he or she doesn’t end up stranded on the road. Check and adjust all tire pressures, including the spare tire. Many shops will have an oil change safety checklist for you to follow.

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PHOTO SEQUENCE 7

Typical Procedure for Resetting the Engine Oil Life Indicator/Reminder

P7-1

P7-4  Common procedures for resetting the oil change reminder/indicator include the following: (1) turning the ignition to on with the engine off, (2) pressing and releasing the accelerator pedal three times within 5 seconds, (3) following message center screen prompts, or (4) using a special reset or scan tool. Be sure to follow the owner’s or service manual for the specific steps.

P7-2

P7-3

P7-5  Some vehicles will require a special scan tool to reset their oil change reminder/­ indicator light.

P7-6  Some vehicles have a multifunction touchscreen that requires you to input data, such as next service date, on the vehicle.

Communicate any problems you find to the service advisor or customer; the customer may choose to have repairs done immediately. Some engines require pre-oiling before they are started after an oil change. This is especially true of engines equipped with turbochargers. The turbocharger rotates at a high rate of speed and requires lubrication to prevent damage. After the oil is drained and the oil filter replaced, it may take several moments before oil reaches the turbocharger. ­Pre-oiling the engine ensures that all components receive oil before the engine is started. Use the following procedure to pre-oil the engine: 1. Make sure the oil filter and crankcase are filled with oil. 2. Disable the ignition system using the manufacturer’s recommended procedure. 3. Crank the engine for 30 seconds, allow the starter to cool, and crank the engine for another 30 seconds. 4. Repeat this procedure until oil pressure is indicated (oil pressure indicator light off or oil pressure gauge indications). 5. Enable the ignition system, and start the engine. 6. Observe the oil pressure indicator. If oil pressure is not indicated, shut off the engine. 7. With the engine turned off, recheck the oil level.

Caution Overtightening the oil filter may cause seal damage and result in oil leakage.

Caution Make sure the crankcase has sufficient oil before cranking the engine, because the oil level will go down when oil flows through the engine lubrication system.

After filling the engine with oil and starting the vehicle, shut the engine off and recheck the fluid level and top off as needed. Lift the vehicle, and double-check for leaks before letting the vehicle go. Lower the vehicle, and check and adjust the other fluid levels. Install Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-24  Always put an oil sticker on the windshield or in the driver’s doorjamb to remind the customer when to have the oil changed again.

Figure 4-25  Many newer vehicles have a computer program that makes the driver aware of the need to change oil.

Figure 4-26  Frequently checking the engine temperature and warning ­indicators during a test drive is a common diagnostic step.

an oil sticker on the windshield or door jam instructing the customer when to have the oil changed again (Figure 4-24). Some vehicles have an oil change reminder or oil life indicator (Figure 4-25). These are part of a computer program that takes into consideration several factors such as temperature, drive time, pressure, and driving habits. The computer will then calculate, by best estimates, when the oil is required to be changed. It is the job of the technician to reset these lights and warning indicators (Figure 4-26). Sometimes you can simply follow directions on the dash, and other times you will need to use a specialized tool or scan tool to reset the light. Always refer to the service or owner’s manual for details. This is a very important step to take and not forget. Refer to Photo Sequence 8 for the typical procedures for resetting the oil indicator.

Oil Level and Condition When checking the oil level and condition, it is important to keep several things in mind. First, never assume anything about the owner’s methods of maintaining their vehicle. They may have a dirty and rusty car but have great maintenance habits. And the opposite is true: A perfectly clean and newer car may look good, yet not be maintained properly. As you grow as a professional technician, you will learn this. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 8

Typical Procedure for Changing Engine Oil

P8-1  Open the hood and pull the dipstick out slightly. Remove the oil cap.

P8-2  Raise the vehicle, locate the oil drain plug, and position the oil drain pan so that it will contain the oil. Note: The oil will come out with light pressure, and it will cause a stream to go to the side. Adjust for this by moving the oil drain pan to the side.

P8-3  Remove the oil drain plug, using a wrench. Note: Always use a properly sized wrench. You will find that over time the oil drain plug head will get rounded by the use of incorrectly sized tools. It will need replacement if it is difficult to remove.

P8-4  Watch the oil coming out of the pan. The content, color, and clarity will give you clues to how often it is maintained and if there are any problems.

P8-5  Adjust the oil drain pan location as needed when the oil flow becomes less.

P8-6  After the oil is done draining, reinstall the oil drain plug with a torque wrench. Use the service manual to find the specification.

P8-7  Remove the oil filter. You may need to use an oil filter wrench if it is tight. There are several types to use. Oil filters are located in different places on different vehicles.

P8-8  Make sure that the oil filter gasket is removed with the old filter. Double-check the engine side to make sure it is not there. Caution: If you do not remove the old oil filter gasket from the engine, when you install the new one, it will have two gaskets. This is called “double gasketing” an engine. This can cause oil to leak from the space in between the two gaskets at a very high rate and pressure.

P8-9  Lubricate the new oil filter gasket with new oil before installing it. Tighten the oil filter one-half turn past hand tight. Do not use any tools to tighten it.

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PHOTO SEQUENCE 8 (CONTINUED)

P8-10  Some vehicles have a cartridge-style oil filter that requires a socket to remove.

P8-11  Similarly, lubricate the new oil filter O-ring if it is a cartridge style. Use a torque wrench to tighten the housing cover of a ­cartridge filter (if equipped).

P8-13  Check the level on the dipstick before starting the engine. If needed, add oil.

P8-14  Start the engine. Immediately watch the oil pressure light or gauge. The engine should have oil pressure within 5 seconds.

P8-12  With the drain plug and filter tight, add the correct amount and type of oil to the engine.

P8-15  If it does not have pressure, then turn the engine off and inspect. With the engine still running, walk around and look under the engine for any leaks.

P8-16  Turn the engine off, wait 30 seconds, and recheck the oil level. It should have gone down just a little bit, because oil is filling into the new filter. Adjust the oil level as needed.

When checking the oil level, you must keep the vehicle on a level surface. The engine must be turned off, and you need to wait up to 30 seconds after the engine is shut off before checking the level. On some vehicles it may take that long just to let all of the engine oil that is circulating throughout the engine get back to the oil sump (pan). When you check the oil, you must take into consideration the temperature of the engine. Most dipsticks have markings on them that indicate where the oil level should be Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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(low or high) and where it should be with regard to temperature. When you pull the dipstick out to check it, hold it level so the oil doesn’t slide off the markings, or it may cause you to think that there is too much or too little oil in it. When you check the condition of the oil, you should be checking the color, clarity, smell, and feel of the oil. The color of oil in good shape should be a golden or tan color. Over time, the oil will get dirty. It is supposed to do that. Dirty oil cannot protect the engine as well as clean oil can, and it can cause small scratches on engine parts like bearings. The oil should smell clean. This is difficult to describe in a book, but when you get a chance open a new bottle of oil and get used to the smell. Dirty oil smells burnt. Sometimes you will smell gasoline or coolant on the dipstick. Neither one of these conditions is good. Gasoline means that the engine either is running rich or has excessive blowby (worn cylinders). Coolant mixed with oil means that a gasket has blown or a component has cracked. Both of these situations can cause the oil to thin (have a lower viscosity). This may not be able to protect the engine; it may destroy an engine or at least cause severe damage. When you feel the oil, it should feel smooth. There should be no grit or dirt in it. Oil sludge is an issue with some engines. This happens when the oil overheats in local areas of the engine. It can cause low oil pressure issues. Sometimes when you visually look at oil, it will have a light tan-colored foam on it. This is water condensation. To a certain point this is normal on some vehicles. But excessive water buildup can mean that coolant (which contains water) may be getting mixed into the oil. It can also mean that a part of the PCV system is restricted. Always check for technical service bulletins (TSBs) related to oil condition. If you are working with a diesel engine, then the color will most likely be a dark black. Most diesel engines must go by the mileage and usage to tell when their oil needs changing. Some shops can test the condition of the oil by doing a lab analysis on a sample of oil. On a diesel engine this helps tell when the oil needs to be changed, it helps save the customer money by doing an oil change only when needed, and it saves the engine from damage by testing the oil periodically.

Oil Consumption Some engines have known problems with oil consumption. If you are working with any engine under warranty, you will be required to carefully document and track a vehicle’s oil consumption. Always refer to the manufacturer’s TSBs and the manufacturer’s guidelines for how much oil consumption is considered acceptable. All engines will consume a small amount of oil because the piston rings will never seal the combustion chamber 100 percent. For most engines and manufacturers, it is acceptable for an engine to consume 1 quart for every 1,000 miles. Always check the manufacturer’s information for TSBs.

Classroom Manual Chapter 4, page 66

COOLING SYSTEM TESTING AND SERVICE It is the function of the engine’s cooling system to remove heat from the internal parts of the engine and dissipate it into the air. Engine overheating is a common cause of internal engine damage, cracked cylinder heads, and blown head gaskets. Proper engine operation and service life depend upon the cooling system functioning as designed. Since the cooling system requires periodic maintenance, most service procedures can be performed with the engine still in the vehicle. Whenever the engine is rebuilt, it is a good practice to remove the radiator and replace it or have it professionally cleaned. In addition, the block and cylinder head passages should be thoroughly cleaned.

The radiator is a series of tubes and fins that transfers the heat in the coolant to the air.

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Most of the remaining cooling system components are replaced whenever the engine is rebuilt. These components include the following: ■■ Water pump ■■ Thermostat ■■ Radiator hoses ■■ Heater hoses ■■ Radiator cap ■■ Coolant ■■ Drive belt

SERVICE TIP  It is a good idea to flush the heater core prior to reinstalling the engine into the vehicle.

Cooling System Maintenance Cooling system maintenance consists of keeping the coolant clean and at the proper level, inspecting for leakage, and checking the condition of the belts and hoses.

Classroom Manual Chapter 4, page 76

Checking Coolant Level.  Checking coolant level on older vehicles without a recovery system should only be done with the engine cool. These vehicles require the radiator cap to be removed so the technician can see if the coolant level is above the radiator tubes. Regardless of the system used, removing the radiator cap on a hot engine will release the pressure in the system, causing the coolant to boil immediately. This can cause coolant to be expelled from the radiator at a high rate, resulting in severe burns. Today’s vehicles are equipped with a coolant recovery system, so the radiator cap usually does not need to be removed to check or add coolant to the system. The coolant reserve system provides quick visual checks of coolant level through the translucent bottle. Simply observe that the level is between the ADD and FULL marks while the engine is idling and warmed to normal operating temperature. If coolant needs to be added, the coolant should be added directly to the coolant recovery tank. On vehicles that use a remote mounted pressure tank or reservoir, look at the minimum and maximum level markings on the tank and make sure the fluid is between the two marks. Be careful when opening the tank to top off a system; the tank will be under pressure if the system is hot. Manufacturers will specify the correct coolant for each vehicle. Proper coolant is critical as most coolants are not compatible with each other or a particular cooling system. Use the recommended coolant and do not mix coolants. If the improper coolant is present in the system, drain it thoroughly or flush it, and then refill with the correct coolant. Cooling System Inspection.  The antifreeze content in the coolant may be tested with a coolant hydrometer, refractometer (Figure 4-27), or coolant test strips. The vehicle manufacturer’s specified antifreeze content must be maintained in the cooling system, because the antifreeze contains a rust inhibitor to protect the cooling system. Always check the vehicle or service manual for the type of coolant to add to the system (see Figure 4-28). Inspect the coolant for rust, scale, corrosion, and other contaminants such as engine oil or automatic transmission fluid. Aside from a visual check of coolant condition, a paper test strip can be used to test the coolant pH level. This will give you a visual indication of whether the coolant has become too acidic and requires flushing. If the coolant is contaminated, the cooling system must be drained and flushed (Figure 4-29). If oil is visible floating on top of the coolant, the automatic transmission cooler may be leaking. This condition also contaminates the transmission fluid with coolant. If the vehicle has Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-27  This refractometer can be used to determine the antifreeze ­protection level of any type of coolant.

Figure 4-28  This under-hood label indicates that the vehicle requires an extended-life coolant. Always use the proper type of coolant.

Figure 4-29  This coolant reservoir is covered in sludge; the system should be flushed and refilled with clean coolant.

an external engine oil cooler, it may also be a source of oil contamination in the coolant. These coolers may be pressure tested to determine if they are leaking. Testing or repairing radiators and internal or external oil coolers is usually done by a radiator specialty shop. Inspect the air passages through the radiator core and external engine oil cooler for contamination from debris or bugs. These may be removed from the heater core with an air gun and shop air, or water pressure from a water hose. Visually inspect the radiator and all cooling system hoses for leaks. Leaking components must be replaced or repaired. Inspect the heater core area for signs of coolant leaks. Some vehicles have the heater core mounted under the dash, while other vehicles have this component under the hood. If the heater core is mounted under the dash, a leaking core may cause coolant to drip on the floor mat. Check all the radiator and heater hoses for soft spots, cracks, bulges, deterioration, and oil contamination. Replace hoses that indicate any of these conditions. Inspect the radiator and heater hoses for contact with other components that could rub a hole in the hose. Reroute other components away from the hoses if necessary. Be sure all the hose clamps are tight and in satisfactory condition. Inspect the Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Weep hole

Figure 4-30  This water pump had been leaking from the weep hole.

engine for coolant leaks at locations such as the thermostat housing, core plugs, and water pump. Coolant leaks at the water pump usually appear at the water pump drain hole or behind the pulley (Figure 4-30). A leaking water pump must be replaced. Each type of coolant reacts differently when it comes in contact with oxygen. If the cooling system was not bled properly, oxygen will enter the system. Excess oxygen can cause the coolant to oxidize or possibly gel. When engine coolant starts to gel up, it becomes thicker. It will start to stick to the walls of the cooling system, causing the heat transferring capability to be diminished, acting like a thermal blanket. This may cause certain engine parts to overheat, but the coolant temperature gauge (or warning light) will not show any severe change in fluid temperature. Always check the manufacturer’s service manual for interval changing periods, and frequently check TSBs for information regarding specific models.

Belt Tension Gauge A belt tension gauge is used to measure timing or drive belt tension. The belt tension gauge is installed over the belt and indicates the amount of belt tension (see Chapter 3, Figure 3-17). A different type of tool called a cricket can be used to check a serpentine, micro-v, or v-belt’s tension. To do this, place the tool on an unsupported part of the belt and push down with your finger until you hear the tool crack. When this happens, you take the tool off and read the gauge (see Chapter 3, Figure 3-18). Modern drive belts are often made with EPDM (ethylene propylene diene monomer). EPDM belts do not crack when they stretch and wear out, although all belts become thinner when they wear out. To check a belt with EPDM, use the special tool to check the depth of the belt (Figure 4-31). The tool will fit loosely into the ribs of a worn belt and fit snugly on a good one.

Figure 4-31  A special belt depth tool is used to check a belt’s condition. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

For further inspection, check the water pump drive belt for cracks, missing chunks, fluid contamination, fraying, and bottoming in the pulley. If the belt makes noise or experiences edge wear, pulley misalignment may be present. Pulley alignment can be checked using a straightedge or a piece of string or wire, but it is best checked using a laser alignment tool. If the belt indicates any of these conditions, belt replacement is necessary. Belt tension may be tested with the engine stopped and a belt tension gauge installed over the belt at the center of the longest belt span. When the belt tension is not within specifications, adjust the belt as necessary. Many ribbed and micro V-belts have an automatic tensioner and do not require adjusting. Some automatic belt tensioners have a wear indicator that indicates the amount of belt wear. The replacement of a belt will vary depending on what type of application it is in. An automatic tensioner comes off easily when a ratchet, wrench, or special tool is used. A manual tensioner is released by loosening a bolt that holds tension on a pulley. A stretch fit belt has to be cut to be removed. Draining the Cooling System.  Because most manufacturers recommend periodic coolant changes, a drain plug is usually provided at the bottom of the radiator (Figure 4-32). Following is a typical procedure for draining the cooling system:

Starting the engine is required to move the heat control valve on vehicles that are actuated by vacuum.

1. Allow the engine to cool. Never open the radiator cap, open the drain plug, or disconnect a hose while the system is pressurized. 2. Start the engine. 3. Move the temperature selector of the heater control panel to the full heat position. 4. Shut off the engine before it begins to warm. 5. Without removing the radiator cap, loosen the drain plug. 6. The coolant recovery tank should empty first. Then remove the radiator cap to drain the rest of the system. 7. On most engines, it will be necessary to drain the block separate from the radiator. Remove the drain bolt from the side of the engine block to drain the block and heater core.

Rusted fins

165

Drain port

Figure 4-32  The small tube at the bottom right of the radiator serves as a drain tube. This radiator has badly damaged fins and caused overheating, which blew a head gasket. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

WARNING  Do not let the used coolant into the shop drains; collect it in a drain pan. The used coolant should be recycled or removed as a hazardous waste.

Many shops now use a coolant flushing machine that automatically expels the used coolant and refills the system with fresh coolant (Figure 4-33). Many of these pieces of equipment also recycle the coolant to eliminate costly removal from the shop. Follow the instructions provided by the equipment manufacturer to flush the cooling system. Do not use recycled coolant if the manufacturer recommends against it; that could nullify the powertrain warranty. While the system is drained, it is a good time to replace the thermostat and hoses. The following is a typical procedure for thermostat replacement (Figure 4-34). Drain the coolant to a level below the thermostat housing. Doing this will reduce the potential to spill coolant onto the floor. Remove the radiator hose from the housing. Some hoses use a worm-gear-type hose clamp. These can be removed by using a flat blade screwdriver to turn the worm gear. Some hoses will have a spring wire clamp; use special clamp pliers or large pliers to remove these clamps. Some engines will have a bypass hose connected to the thermostat housing; if this is the case on your engine, it should be removed at this point. Loosen and then remove the fasteners that attach the thermostat housing to the engine. It may be necessary to strike the housing with a rubber mallet to break the seal between the engine and the housing. Do not drive a chisel or flat-blade screwdriver between the mating surfaces; doing so may damage the mating surfaces and prevent the system from sealing. Remove the thermostat and gasket or O-ring seal. Pay attention to the direction the thermostat was facing. Confirm the proper direction in the service manual. If the thermostat was installed backward, it could have been the cause of overheating.

Upper radiator Thermostat housing hose

Figure 4-33  A coolant flushing machine.

Figure 4-34  The thermostat sits on the top front of this engine.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

SERVICE TIP  The condition of the antifreeze can be checked using a digital voltmeter. The red voltmeter lead is inserted into the coolant, while the black lead is attached to a good engine ground. If the voltmeter reads 0.2 volt or less, the antifreeze is good. A reading between 0.2 and 0.6 volt indicates that the antifreeze is deteriorating and is borderline. A voltage value above 0.7 volt indicates that the antifreeze must be changed. High voltage values can also indicate a bad ground or a blown cylinder head gasket. The voltage reading is the result of the chemical reaction between the engine block materials and the coolant known as e­ lectrolysis. As the additives in the antifreeze deplete, the antifreeze becomes a weak acid. The result is the cooling system produces a galvanic reaction similar to a battery.

Being careful not to gouge the metal, use the proper abrasive disc to clean both mating surfaces. Apply the correct sealant, if one is recommended, to the mating surface of the housing. Carefully install the thermostat in the engine block, being sure the pellet is facing the correct direction (usually the pellet faces into the block). A small indented ridge is generally provided for the outer portion of the thermostat to seat into. Make sure the thermostat does not slip during the rest of the installation process, or a leak may result. Install the gasket or O-ring seal. Some manufacturers use a locating tab or notch for proper indexing of the O-ring seal. Carefully locate the housing over the thermostat, and align the holes with the block. Install and torque the fasteners. Install all hoses to the thermostat housing. It is a good practice to use new clamps to ensure no leaks will occur. If using the worm-gear-type clamps, do not overtighten them: doing so will cut the hose and cause a weak spot that may begin to leak in a few months. After confirming that all connections are tight, refill the cooling system. Filling the Cooling System.  The cooling system is usually filled with a mix of 50/50 antifreeze to water. To fill the cooling system, make sure all hoses are installed and clamps are tight. Also, close the drain plug before filling. Look up the cooling capacity in the service manual. Fill the system half of capacity with 100 percent antifreeze through the radiator cap opening. Then complete filling with water. Since many vehicles are designed with the radiator lower than the engine, a bleed valve is used when filling the system (Figure 4-35). Loosen the bleed valve while the radiator is being filled. Close the valve when coolant begins to flow out in a steady stream without bubbles. Leave the radiator cap off, and start the engine and let the engine warm up. Continue to fill the radiator as

Upper radiator hose

Drain bolt

Bleed bolt

Figure 4-35  A bleeder bolt may be located on the thermostat housing or on another high spot in the cooling system. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Some coolants are now sold premixed with water; be careful not to dilute these coolants. Refer to Today’s Technician™: Automotive Heating and Air Conditioning.

Special Tools Flush gun Aluminum hydroxide deposits result from corrosion products being carried to the radiator and deposited when cooled off. They appear as dark gray when wet and white when dry.

needed as the engine warms. When the radiator is full, install the radiator cap, and allow the system to pressurize while observing for leaks. It will probably be necessary to add additional mix to the recovery tank. It may take as many as four warm-up cycles before all of the air is removed from the system and the recovery tank equalizes. Cooling System Flushing.  The effectiveness of antifreeze and the additives mixed with it decreases over time. All manufacturers have a maintenance requirement for the cooling system. The recommended schedule for drain, flush, and refill ranges from once a year to once every five years. At the same time that the refill is performed, the thermostat is generally replaced along with the water pump drive belt. While many shops are now using automatic flushing machines, flushing of the cooling system can also be accomplished by using pressurized water forced through the cooling system in a reverse direction of normal coolant flow. A special flushing gun mixes low air pressure with water. Reverse flushing causes the deposits to dislodge from the various components. They can then be removed from the system. The engine block and radiator should be flushed separately. To flush the radiator, drain the radiator and then disconnect the upper and lower radiator hoses. A long hose may be attached to the upper hose outlet to deflect the water. Disconnect and plug any heater hoses that are attached to the radiator. Fit the flushing gun to the lower hose opening. This causes the radiator to be flushed upward (Figure 4-36). Fill the radiator with water, and turn on the gun in short bursts. Continue to flush the radiator until the water being expelled from the upper hose outlet is clean. To flush the engine block, disconnect the radiator upper and lower hoses. Also, remove the thermostat and reinstall the thermostat housing. Install the flushing gun to the thermostat housing hose (Figure 4-37). Turn on the water until the engine is full. Then turn on the air in short bursts. Allow the engine to refill with water between blasts of air. Repeat this process until the water runs clean. Water is usually sufficient to remove most contaminants from the cooling system. However, aluminum hydroxide deposits require a two-part cleaner to remove them. The two parts are an oxalic acid and a neutralizer. The acid is added to the system first.

Attach flush gun to upper radiator hose

Attach flush gun to lower radiator hose

Upper engine hose is removed and new long hose installed

Radiator cap remains sealed

Thermostat housing with thermostat removed

Flush until water runs clear

Lower radiator hose Flush until water runs clear Radiator

Figure 4-36  Reverse flushing the radiator.

Figure 4-37  Reverse flushing the engine block.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Then the engine is allowed to idle for the specified length of time. The cooling system is then flushed. After the flush is completed, the neutralizer is added to prevent the acid from damaging metal components. If chemical cleaning fails to remove the deposits, the radiator will need to be removed and “boiled out.” Care should be taken to select the proper solutions and solvents to clean the radiator. Clean it in a solvent that is not destructive to the type of materials used to construct the radiator. After removing the radiator from the solvent, flush it until all of the solvent is removed. Flush the transmission cooler too, if the radiator is equipped with one. It may be necessary to use a neutralizer if an acid solvent is used. Check the fins for damage, and straighten any that are bent. After the radiator is cleaned and flushed, pressure test it to ensure there are no leaks.

169

Caution Do not allow internal pressures in the radiator to increase over 20 psi (138 kPa) or damage to the radiator could result.

Cooling System Component Testing Testing the Thermostat.  If a customer brings in a vehicle with an overheating problem, it is possible the thermostat is not opening. In addition, an engine that fails to reach normal operating temperature can be caused by a faulty thermostat. A thermostat that is not opening will cause the coolant temperature gauge to rise steadily into the red zone after several minutes of operation. Sometimes the thermostat will stick closed intermittently. The customer may report that the coolant gauge spiked into the red and then came back down to a normal reading one or more times. The thermostat is inexpensive; problems caused by engine overheating are not. It is wise to replace the thermostat if you suspect that it is sticking. Thermostats have a high failure rate and are often replaced simply based on the symptoms described or as part of routine maintenance. To attempt to verify a sticking thermostat, start the engine while it is relatively cool. Use a contact thermometer or an infrared pyrometer to monitor the temperature of the upper radiator hose as the engine warms up. Periodically check the coolant temperature gauge to make sure the engine does not overheat. If the thermostat is working properly, the upper radiator hose should get quite hot and feel pressurized as the temperature gauge rises into the normal zone. If the gauge starts to read high and you have not felt a distinct temperature increase in the hose temperature, the thermostat is sticking closed. Replace a faulty thermostat. You can also test for a stuck-open thermostat using a similar method. Start the engine after it has cooled. Monitor the upper radiator hose toward the radiator end after letting the vehicle run for a few minutes. If the hose starts to get warm within the first few minutes of operation or before the engine reaches a normal temperature, it is sticking open. Sometimes you may have to remove the thermostat to try to verify that it is faulty and causing the system overheating. Check the rating of the thermostat, and confirm it is the proper one for the engine application. Also confirm it was installed in the right direction. It is possible to test thermostat operation by submerging it in a container of water and heating the water while observing the thermostat. Use a thermometer to determine the temperature when the thermostat opens. At the rated temperature of the thermostat, it should begin to open.

Special Tools Thermometer

Special Tools Jumper wires Scan tool

Classroom Manual Chapter 4, page 82

WARNING  Do not open a hot radiator. The radiator is under pressure, and opening the cap will cause hot coolant to spray out of the filler tube.

Cooling Fan Inspection.  The fan can be driven by a drive belt off of the crankshaft, or it can be operated electrically (Figure 4-38). Regardless of the design used, inspect the fan blades for stress cracks. The fan blades are balanced to prevent damage to the water pump bearings and seals. If any of the blades are damaged, replace the fan. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

170

Chapter 4 Flexible trailing edge

Water pump pulley

Rigid leading edge

FRONT Radiator

Lower radiator supports

Flex fan assembly

Spacer

Motor coolant fan Electrical wiring harness

(A)

(B)

Figure 4-38  (A) Belt-driven fan. (B) Electric fan.

Cooling fans force airflow through the radiator to help in the transfer of heat from the coolant to the air. Flex fans widen their pitch at slow engine speeds when more airflow is required through the radiator fins. At higher engine speeds, the pitch is decreased to reduce the horsepower required to turn the fan.

WARNING  An electric fan may start at any time, even after the engine has been turned off. Disconnect the fan electrically before touching the fan.

The drive belts should be inspected for glazing, cracking, and proper tension. A belt that is worn or loose will not turn the fan at a sufficient speed to draw the optimum mass of air over the radiator. Most modern engines using belt-driven fans use either flex fans (Figure 4-39) and/ or a viscous fan clutch (Figure 4-40). Some newer engines may use an electrically operated viscous fan clutch (Figure 4-41). Flex fans are inspected for stress cracks as any other fan. The viscous fan clutch should be visually inspected for indication of silicone leakage. Electric fans are also inspected for damage and looseness. If the fan fails to turn on at the proper temperature, the problem could be the temperature sensor, the fan motor, the

0 rpm

2,500 rpm

Figure 4-39  The flex fan is capable of changing its pitch.

Figure 4-40  A thermo-viscous clutch fan.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Figure 4-41  This clutch fan is electrically controlled by the PCM.

fan control relay, the circuit wires, or the PCM. To isolate the cause of the malfunction, attempt to operate the fan by bypassing its control. On many modern vehicles, this can be done by using a scan tool to activate the fan. If the fan operates, the problem is probably in the coolant sensor circuit. It is also possible to check fan function by jumping the fan relay to attempt operating the fan motor (Figure 4-42). You must be careful to only jump the power waiting terminal to the switched power out terminal; these are often labeled number 30 and number 87, respectively, on the relay. If the fan operates, the relay may be the faulty component; however, additional tests will have to be performed on the control circuit of the relay. To direct airflow more efficiently, many manufacturers use a shroud (Figure 4-43). Proper location of the fan within the shroud is also required for proper operation. Generally, the fan should be at least 50 percent inside the shroud. If the fan is outside the shroud, the engine may experience overheating due to hot under-hood air being drawn by the fan instead of the cooler outside air. If the shroud is broken, it should be replaced. Do not drive a vehicle without the shroud installed.

Fan control relay

Temperature sensor switch –

+ Battery

Jumper wire

Fan motor

Figure 4-42  Jumping the high current side of the relay connector to test the fan motor.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Radiator

Figure 4-44  Typical belt tensioner.

Fan shroud

Figure 4-43  The fan shroud is used to control the airflow direction.

SERVICE TIP  If the shroud is not severely damaged, it can be repaired using hot-air or airless welding. If this welding equipment is not available, it will be necessary to glue the shroud. It is hard to find a glue to hold polyethylene or polypropylene plastic. One method is to apply SuperGlue® to the seams of the break, and while applying pressure to hold the two pieces together, spread baking soda onto the crack. The baking soda creates a chemical action that results in a harder setting of the glue. Apply additional glue on the top and bottom of the crack, and add more baking soda as needed. The baking soda will become extremely hard, and it can be sanded and then painted as needed. If the shroud is constructed of fiberglass, it can be glued with epoxy.

Also inspect the idler pulley and belt tensioner, if equipped (Figure 4-44). Many manufacturers use idler pulleys so components such as alternators, air-conditioning ­compressors, power steering pumps, and so forth will be provided a greater area of belt contact on their pulleys (Figure 4-45). Tensioners are used to properly maintain drive belt tension. Most tensioners are spring- or silicone-filled to provide self-adjustment. Test the pulley for free rotation, and inspect for any wear grooves or looseness. If the pulley fails inspection, it must be replaced. There is no service available on these units. If the belt squeals just after the engine starts or as the engine is quickly accelerated, the belt tension may be less than it needs to be. A squealing belt means that it is slipping. If the belt slips, the accessories are not spinning as fast as they should. This may include critical items such as the water pump and alternator. If the belt system uses an automatic tensioner, you can test one by first removing the belt. Then place a ratchet, socket (or in some cases a special wrench) on the tensioner and attempt to move it back and forth. It should move back and forth smoothly (Figure 4-46). It also should not have any movement on its mounting bolt and not have any grease or silicone leaking from it. Don’t forget to check pulley misalignment for a possible cause of belt squeal.

Water Pump and Radiator Removal Water pump removal is usually performed with the engine in the vehicle. This is usually performed due to coolant loss through the water pump seal or noisy water pump. Radiator removal is usually performed only if the radiator requires special flushing, replacement, or the engine is being removed.

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Diagnosing and Servicing Engine Operating Systems

173

Figure 4-46  Depending on the design, you may be able to use a wrench or ratchet to move the belt tensioner. Figure 4-45  Idler pulleys provide for increased surface area contact of the drive belt. The dotted line indicates belt routing without idler pulleys. The added surface contact helps prevent belt slippage.

On some vehicles, it is necessary to remove the radiator prior to servicing the water pump, so this procedure will be discussed first. It is impossible to cover all of the procedures for removing the radiator on all vehicles. Always refer to the proper service information for the vehicle you are working on. Following is a general guide for radiator removal for vehicles equipped with electric fans (Figure 4-47): 1. Disconnect the negative battery terminal at the battery. This is necessary on vehicles using electric fans, to prevent them from turning on unexpectedly. 2. Drain the cooling system using the procedure covered earlier. 3. Loosen or remove the hose clamps; then remove the upper and lower hoses from the radiator. 4. Disconnect the transmission cooler lines and plug them off, if equipped. 5. Disconnect the electric fan motor connector, if equipped. 6. Remove the fasteners attaching the fan to the radiator. 7. On some vehicles equipped with air-conditioning systems, it may be necessary to discharge the system. This is the case if the radiator and condenser cannot be separated in the vehicle.

Transmission cooler nipples

Caution You must have ­special tools and be certified to perform operations on the ­air-conditioning system that require refrigerant handling.

Classroom Manual Chapter 4, Pages 78 & 82

Drain cock

Dual fan module

Figure 4-47  Radiator with dual fans. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 4

Upper radiator cross member

O-ring seal

Water pump Lower radiator supports Drive pulley (cog belt) from crankshaft Cooling module

Figure 4-48  The radiator is usually supported by an upper mounting that must be removed.

Figure 4-49  A gasket or seal is used between the water pump and the engine block. This water pump is driven by the timing belt; a bit more work is involved in this replacement.

8. Remove the upper radiator cross member or mounts (Figure 4-48). 9. Disconnect and plug the air-conditioning lines at the condenser, if needed. 10. Remove the radiator and fan as one unit if possible. 11. Separate the fan from the radiator. 12. If required, separate the radiator from the condenser. It is not always necessary to remove the radiator to service the water pump; however, on many vehicles, the fan shroud must be separated from the radiator to gain access to the fan mounting bolts. Once the fan is separated from the water pump, the shroud and the fan assembly can be removed together. Most water pumps can be removed after disconnecting the lower radiator hose at the pump (drain the cooling system first). Remove any other hoses that attach to the pump, such as bypass hoses. When removing the bolts attaching the pump to the block, note the location of each bolt in the pump. There are usually several different lengths of bolts used. Installing the wrong bolt in the wrong location can cause block damage or leaks. Most water pumps have gaskets or seals located at the mating surface to the block (Figure 4-49). Be sure to thoroughly clean the surfaces and to use the approved sealer. SERVICE TIP  It is common practice to replace timing belt–driven water pumps when replacing the timing belt and the tensioner.

GALLERY AND CASTING PLUGS

Special Tools Plug driver Bore brush

The oil gallery and coolant passages are important parts of the lubrication and cooling systems. Plugs are located on the block and cylinder head assemblies to cap the openings used for casting the block or for drilling the passages. Over time these plugs can rust through or work loose. In many cases, plugs can be replaced while the engine is still in the vehicle; however, anytime the engine is removed for service, it is common practice to replace all plugs.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems Sealing edge before installation

Cup-type plug

Cup-type core plug replacer tool

Figure 4-50  Installing a cup-type core plug.

Sealing edge before installation

Expansiontype plug

Expansion-type core plug replacer tool

Figure 4-51  Installing an expansion-type core plug.

Plugs can be either threaded in or pressed in. There are three basic designs of press-in plugs: 1. Disc-type plugs are installed with the convex side facing out. As the plug is driven into its bore, the crown is flattened. This causes the sides to push outward, providing a tight seal. 2. Cup-type plugs are installed with the convex side facing in (Figure 4-50). The sides of the plug are tapered so that the widest part is at the outer edge. The taper assists in the installation of the plug and works to seal the plug. 3. Expansion-type plugs have tapered sides with the narrow end at the outer edge (Figure 4-51). The convex side of this plug is installed facing out. As the plug is driven into place, the sides will expand outward and seal the plug. Pressed-in gallery plugs can be removed using a slide hammer with a self-threading screw. Center drill the plug, and then thread in the self-threading screw. With the slide hammer attached to the screw, work the sliding weight until the plug is removed. It is also possible to install a self-threading screw into the plug and to pry the plug out by gripping the screw with a pair of pliers or side cutters. Core plugs can be removed using the previous method or by tapping one edge with a punch to turn the plug 90 degrees in the hole (Figure 4-52). Use a pry bar or pliers to force the plug out of the hole. If the plug falls into the water jacket, it must be removed. The plug can usually be gripped with a pair of pliers and pried out of the opening.

Core plug

Drift

Remove loose plug with pliers Drive core plug inward at bottom

Figure 4-52  Removing the core plug.

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Chapter 4

Caution Driving a core plug in too far can cause damage to the ­cylinder wall.

Special Tools Steam cleaner Chemical dye leak detector Black light Leak tracing powder Soapy water Stethoscope Infrared exhaust analyzer Blow gun High-pressure air adapters

Caution Be sure all sealers used are oxygensensor safe. Some sealers will cause the sensor to fail.

Threaded gallery plugs may be difficult to remove. Over the life of the engine, these plugs expand and contract several times. In addition, contamination can accumulate around the threads and cause them to “seize” to the cylinder head. Whenever the block or cylinder head is serviced, these plugs must be removed for proper cleaning. To remove a seized gallery plug, it may be necessary to heat it and then spray it with penetrating oil after it cools. Another method is to heat the plug and then lay a piece of paraffin wax against the exposed threads of the plug. The wax will melt and work its way down the threads, lubricating them. Plugs with damaged heads or threads can be removed using the same type of equipment used to remove damaged fasteners. Common methods include using left-handed drill bits, or center drilling the plug and using a screw extractor to remove it. Refer to Chapter 5 of this book for the procedures to extract damaged fasteners. Oil gallery and core plugs are under pressure when the engine is running, so proper sealing is important. Coat the threads or flanges with a water-resistant sealer prior to installing the plug. Be careful to keep any chemical sealers off the end of the plug, where it can be washed into the engine oil. Start threaded gallery plugs by hand; then tighten them to the proper torque. Most threaded plugs use a taper pipe thread. These plugs will not fully seat until they are tightened. CUSTOMER CARE  Always protect the customer’s vehicle. The customer has worked hard to be able to afford the vehicle. Respect the owner and his possession by using fender covers, seat covers, and floor mats to protect the vehicle’s finish and interior. Keep your hands and clothes clean if you need to enter the vehicle. Attempt to return the vehicle to the customer as clean as or cleaner than when he or she left it in your care.

LEAK DIAGNOSIS Caution Always check the engine oil level before starting the engine. Remember, the vehicle was brought to the shop because of oil leaks. If the oil level is low, add oil to the crankcase to bring the level to the full line. It takes only a matter of seconds to severely damage an engine if it is run with a low level of lubricant. Classroom Manual Chapter 4, page 71

Oil and coolant leaks can cause serious engine problems. Running an engine low on oil or coolant can quickly turn the engine into scrap metal. Most external leaks are the result of deteriorating seals or gaskets. Additional causes include defective components and cracks in the cylinder block or head. Oil Leaks.  The most common locations for oil leakage are at the valve cover, oil pan, oil filter, front seal, and rear main seal. Other locations include the camshaft expansion plugs and timing chain cover (Figure 4-53). When inspecting these areas, look for wash where the oil has left a trail. Oil contains cleaning agents, and many times the area around the leak will be washed clean by the oil. WARNING  Follow all safety rules associated with hoist or floor-jack and safety-stand use if the vehicle must be lifted from the floor.

Regardless of the location of the leak(s), the technician must be aware that even the smallest of leaks can result in major oil loss. It is estimated that three drops of oil leaking every 100 feet results in a total loss of 3 quarts every 1,000 miles. Oil leakage occurs under two different conditions: normal and abnormal crankcase pressures. Seals and gaskets can leak when crankcase pressures are normal. Most of this leakage is due to normal wear; however, some leakage resulting from normal crankcase pressures is not the result of normal wear, including damage to seals and gaskets as a result of overheating or lack of oil. This damage is usually identified by excessive warping and discoloring of metallic components.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

177

Cap or grommets Head cover

Head Head gasket Oil pressure switch Engine block Oil filter

Crankcase

Dipstick tube

Front or rear seals

Figure 4-53  Common locations for external oil leaks.

If the crankcase pressures are excessive, early failure of seals will result. Generally, excessive crankcase pressure is developed when the positive crankcase ventilation (PCV) system inlet becomes plugged. The PCV system is designed to control normal engine oil vapor blowby without venting the vapors to the atmosphere (Figure 4-54). If the PCV valve malfunctions, it will not allow ventilation of the crankcase blowby vapors, and the result is excessive pressure. Several methods are used to locate the cause of an oil leak. The first is a complete visual inspection. Look for oil leaking onto the block, pan, and bell housing (Figure 4-55). It may be helpful to clean the engine and then start it to observe where the oil leaks from. WARNING Be careful to avoid hot exhaust manifolds and other engine c­ omponents when looking for the cause of an oil leak, because the engine must be at normal operating temperatures for the inspection to be successful. Moving parts, such as fans, pulleys, and belts, are also a danger.

The positive crankcase ventilation (PCV) ­system is an emission control system that routes blowby gases and unburned oil/fuel vapors to the intake manifold to be added to the combustion process. Blowby is the unburned fuel and products of combustion that leak past the piston rings and enter the crankcase.

PCV valve Front

Blowby gas Fresh air

Figure 4-54  Normal operation of the PCV system reduces crankcase pressures.

Figure 4-55  Fresh oil on the pan indicates the close proximity of an external leak.

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Caution Be sure to use ­regulated air pressure at 5 psi in the crankcase. Using higher pressure can cause seal failure.

The technician should keep two things in mind when performing a visual inspection for an oil leak. First, when the vehicle is stopped, the oil will seek a low point before it drips. Second, when the vehicle is moving, airflow over the engine will spread the oil to other undercar components. In most cases the cause of the leak is at the highest point; oil will travel down and somewhat to either side. If the oil finds its way into a rail or ledge, it will continue to follow that path until it gets to the lowest point. SERVICE TIP  Aerosol-type powder, such as foot powder, can be used to find the leak. Spray the area, and then operate the engine. Inspect the powder for traces of oil. WARNING  Whenever running the engine in the shop, be sure to connect the shop’s exhaust system to the vehicle’s exhaust pipe. Carbon monoxide is deadly.

If oil is spread throughout the undercar components, visual inspection becomes more difficult. In this case, clean the engine and undercar components with a steam cleaner or solvent. Allow the cleaning agents to dry completely. Start the engine, and observe suspect areas while the engine is brought up to normal operating temperatures. Sometimes a leak is more detectable with a cold engine, and in other instances, the leak may not appear until the engine is warm. If the visual inspection fails to locate the cause of the leak, a chemical dye can be added to the engine’s oil (Figure 4-56). First, clean the outside of the engine with a steam cleaner (being cautious to stay away from any air-conditioning components) or solvent. Next, add the recommended amount of dye to the oil. Run the engine for about 15 minutes to allow the oil to circulate throughout the engine. On vehicles with a small leak, it may be necessary to run the vehicle for a longer period or to have the customer return in a day or two. Shut off the engine, and inspect for traces of the dye with a black light. The dye will show fluorescent yellow or orange when the black light is used. A variation of the dye procedure is the use of a light-color leak-tracing powder. The powder will turn brown or black when it comes into contact with oil. Before applying the powder to the outside of the engine, all traces of oil must be removed from the engine. Use a steam cleaner or solvent to thoroughly clean the engine, and allow it to dry completely. Apply the powder to the suspected areas, and start the engine. While the engine is running, observe the powder; it will change color as the oil comes into contact with it. Low- and high-pressure air testing is another method of locating the cause of an oil leak. Low-pressure air testing uses a regulated air pressure of 5 psi (34.5 kPa) and soapy water to locate the leak.

Figure 4-56  Use of a chemical dye and a black light helps in locating the source of a leak. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Hose

Hose clamps Air gun Dipstick tube

Figure 4-57  Use an adapter connected to the dipstick tube to perform a low-pressure air testing.

A hose and clamp arrangement can be made to adapt the air hose to the dipstick tube (Figure 4-57). Pull and plug the PCV valve and breather tubes. Lock or tape the blow gun into the ON position. With a constant amount of air pressure entering the engine, apply the soap and water solution to likely leak areas. A leak is indicated by bubbles created by the escaping air. If the leak is bad enough, it may be possible to hear the air escaping. If low-pressure air testing fails to find the location of the leak, use high-pressure air testing. This test is done by first removing the oil pressure sending unit from the engine. Select the correct size adapters to tap into the threaded hole. Set the regulated air pressure between 80 and 100 psi, and install the blow gun to the adapters. Lock or tape the blow gun ON, and apply the soapy water solution around oil galley plugs, oil filter seals, and any other suspected areas. SERVICE TIP  Use a rubber hose or stethoscope to amplify the noise ­generated by the escaping air.

Once the location of the leak is isolated, the technician should make a determination of the cause. Gaskets and seals can fail due to several factors. One of the most common causes for gasket and seal failure is overheating. Before replacing a faulty gasket or seal, inspect the area for signs of overheating. These include bluing or discoloring of the metal, hardening and cracking of the gasket or seal, and warping of the surface areas. If overheating is not the cause of the failure, check for excessive pressure in the engine crankcase. If the PCV valve malfunctions, it will not allow ventilation of the crankcase blowby vapors, and the result is excessive pressure. Before faulting the PCV valve, check for a plugged filter in the breather line from the valve cover to the air cleaner housing. Quick-check the PCV valve by removing it from the engine and shaking it. A rattle should be heard; if not, the valve is stuck and needs to be replaced. A valve that does not rattle must be replaced; however, a valve that rattles may still be plugged enough to cause pressure. Next, remove the PCV valve from the engine, and allow it to hang free. Listen for a hissing sound from the valve. No sound indicates the PCV valve or hose is plugged. A vacuum should be felt if you place your thumb over the valve opening, and the engine speed should decrease by about 50 rpm. If there are no signs of external oil leaks, yet the engine is using oil, remove the spark plugs and inspect them for indications of oil burning. Oil on the spark plugs indicates valve seal leakage, worn valve guides, or worn piston oil control rings.

Special Tools Chemical dye leak detector Black light Cooling system pressure tester Combustion leak detector Infrared exhaust analyzer

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SERVICE TIP  An oil-covered air cleaner is a clue there is too much ­ ackpressure in the crankcase. This can be caused by a faulty PCV system or by b too much blowby past worn piston rings.

Coolant Leaks.  Cooling system leaks or loss of pressure can occur at many locations (Figure 4-58). When inspecting the engine for coolant leaks, check it both at cold and at normal operating temperatures. Sometimes coolant will only leak at a location when the engine is cold. The cold components are contracted, and gaps appear. As the engine warms, the gaps may close and stop the leak. Other leaks may not appear until the engine is warm and pressures are increased in the cooling system. WARNING  Electric fans can come on at any time. Keep fingers and hands away from the fans. Also, make sure you have no loose clothing or jewelry that can get tangled in the fans.

SERVICE TIP  The cooling system pressure is often indicated on the radiator cap; just be sure it is original equipment. Most systems use 13-lb. to 17-lb. caps. Do not increase pressure over 16 lbs. unless specifications call for higher test pressure. A four-gas exhaust analyzer enables the technician to look at the effects of the combustion process. It will measure hydrocarbons, carbon monoxide, carbon dioxide, and oxygen levels in the exhaust.

Engine coolant leaks that are not easily identified by visual inspection may be located using a cooling system pressure tester (Figure 4-59). To pressure test the cooling system, begin by using the correct service manual for the vehicle and engine being tested, to locate

Overflow recovery tank

Radiator cap

Radiator hose Thermostat

Heater control

Heater core

AIR FLOW Heater hoses

Radiator Water pump

Figure 4-58  Areas from where coolant or pressure can leak. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-59  A cooling system pressure test is used to test for internal and external leaks.

the cooling system pressure specifications. With fender covers properly placed to protect the vehicle’s finish, perform a visual inspection of the hose connections, and tighten any loose clamps (see Photo Sequence 9). PHOTO SEQUENCE 9

Cooling System Testing

P9-1  Visually inspect the coolant and use a coolant analysis strip to test the coolant.

P9-2  Dip the strip in the coolant and compare the colors to the indications in the bottle to determine if the coolant needs to be replaced.

P9-4  On some newer long-life coolants, a refractometer provides a more accurate ­analysis of the coolant.

P9-5  Test antifreeze protection level whenever cooling system maintenance is performed.

P9-3  With many coolants you can use a ­traditional antifreeze protection level tester.

P9-6  Use a cooling system pressure tester to test the system for leaks and to test the function of the radiator cap.

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PHOTO SEQUENCE 9 (CONTINUED)

P9-7  Pressurize the system to the pressure stated on the cap, and make sure the system holds pressure while you look for leaks.

P9-8  Test the radiator cap to be sure it holds pressure. A weak cap can cause boiling over and overheating. The cap should also release pressure above its rating.

P9-10  Use a pyrometer to be sure that the engine is running at normal operating temperature.

P9-9  You can use a chemical block tester to be sure that no combustion gases are leaking into the cooling system from a faulty head gasket.

P9-11  You can check your gauge accuracy by comparing your readings on the engine.

WARNING  Severe burns can result from heated coolant. Wait until the upper tank of the radiator is cool to the touch before opening the pressure cap. Remove the cap slowly to release any pressure in the system.

Remove the radiator cap, and inspect the spring washer for indications of weakness. If the spring is weak, replace the cap. Also, inspect the relief valve gasket on the cap and inner sealing surface of the filler neck for damage or contamination. Clean or replace as needed. Clean the cap and install it on a pressure tester. Pump the pressure tester slowly to obtain minimum holding pressure. A reading less than that specified as the minimum holding pressure in the service manual indicates a defective cap. Remove the cap from the pressure tester, and install the tester on the radiator filler neck. Use the pump to increase the pressure in the cooling system to the specified level. Once the specified pressure has been obtained, a correctly sealed cooling system will maintain it for 15 minutes. If the pressure drops, there is a leak. Visually inspect all possible areas for external leaks. If the leak cannot be found with a pressure tester, use a fluorescent dye similar to that used in locating oil leaks. Use a black light to pinpoint any leaks. If there are no visible signs of external leakage, the cause of the pressure drop is internal. WARNING  Relieve the pressure applied by the tester before removing the test equipment.

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Inspect the oil dipstick and oil filler cap for signs of water, milky-colored oil, or rust. Also, inspect for water on the spark plugs and oil deposits on the radiator filler neck. Any of these indicate that the coolant has entered the crankcase. WARNING  Be careful of moving parts. Fans, pulleys, and belts can cause severe injury.

To test for cylinder head gasket leakage, leave the cooling system pressure tester connected to the radiator filler neck and apply a low pressure of approximately 5 psi. Run the engine at idle while observing the gauge. Excessive pressure buildup indicates combustion chamber pressures are entering the cooling system. A damaged cylinder head gasket or cracked block can also be verified by the use of a combustion leak detector (Figure 4-60). Lower the coolant level in the radiator to allow a 1-inch space above the fluid. Start the engine, and add the special test fluid into the tester. Squeeze the bulb on the tester to draw in gases from above the coolant through the test fluid. If there are combustion chamber gases present in the coolant, the test fluid will change color. It is also possible to use an infrared exhaust gas analyzer. Place the probe over the filler neck with the engine running (Figure 4-61). Do not place the analyzer tip in the fluid. The presence of combustion chamber gases will be indicated by a hydrocarbon (HC) and/or CO reading.

Special Tools Infrared exhaust analyzer A four-gas exhaust analyzer enables the technician to look at the effects of the combustion process. It will measure hydrocarbons, carbon monoxide, and oxygen levels in the exhaust.

SERVICE TIP  A plastic bag held on the filler neck with the engine running can be used to collect any hydrocarbon gases. Then the analyzer probe can be inserted into the bag to check the sample for a blown head gasket.

A third method is to use a chemical tester. The test kit comes with a blue paper. A strip of the paper is soaked in the coolant. If combustion gases are present, the paper turns yellow.

Analyzer

Position the analyzer probe over (not in) the radiator filler neck

Figure 4-60  A combustion leak detector checks for combustion gases in the coolant.

Figure 4-61  A four- or five-gas exhaust analyzer can be used to detect ­combustion gases in the cooling system.

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CUSTOMER CARE  Gallery plugs or soft plugs that are rusted through indicate excessive water in the coolant mixture. If this condition is found, the customer should be advised of the correct coolant mixture to prevent a recurrence of the problem. The cooling system should be flushed when repairs are made.

Occasionally, the crack in the head gasket, head, or block is very small and will cause less-dramatic symptoms. When the engine is cool, the metals in either of the suspect parts contract and enlarge the crack. Coolant may leak into the affected cylinder and foul the spark plug or cause small amounts of white smoke to exit the tailpipe. Symptoms may occur for a short time after start-up; then the engine heat can cause enough expansion in the metal to seal the gap. To confirm your diagnosis, remove the spark plugs, allow the engine to cool thoroughly, and place rated system pressure on the coolant using a pressure tester. Let the vehicle sit for as long as is practically possible but at least one-half hour. Disable the fuel system; have an assistant crank the engine over and watch closely for coolant spray out of a cylinder. Sometimes it is helpful to place a paper towel in front of each plug hole so you are able to check each cylinder. Any coolant from a cylinder indicates a sealing failure. If you are uncertain of the result from a cylinder, you can perform a cylinder leakage test as described in Chapter 7 of the Shop Manual.

WARNING SYSTEMS DIAGNOSIS Engine warning systems must function properly to avoid costly engine failures. Every time you change the oil and filter, you should check that the oil pressure warning light or pressure gauge functions properly. Whenever you service either the lubrication system or the cooling system, test the warning system before returning the vehicle to the customer.

Engine Oil Pressure Warning System Every vehicle has a means of communicating low oil pressure to the driver. Most vehicles use a warning light, either with or without an oil pressure gauge (Figure 4-62). Test to be sure that the circuit is functional by observing the indicator with the key on, engine off. If it does not light, check the oil pressure sending unit wiring, instrument panel bulb, and power supply before starting the vehicle. If the oil pressure warning light is on and no engine noise is heard, check the circuit electrically first. The oil pressure sending unit is typically located near the oil filter housing. Most often, you can remove the single wire from the unit and the light will go off, and ground the wire to clean, bare metal to make the light come on or the gauge rise. Be certain to check the manufacturers’ wiring diagrams and service information first; this procedure could cause damage on some systems! If the circuit appears to function as designed, run an oil pressure test to check your findings. To replace an oil pressure switch, sending unit, or temperature sensor, unscrew it from its bore. If it is physically damaged, be certain you extract all the pieces from the engine block. If specified, use a small amount of thread tape or pipe sealant to prevent leakage. Tighten the unit to specification. Always check for proper operation of the system after replacing a component. Also check for and correct any leaks from the new part.

Cooling System Temperature Warning System Vehicles have either a cooling system warning light or a temperature gauge with a warning light that indicates excessive cooling system temperature to the driver. To test that the warning light is functional, turn the key to the crank position and observe the light. If it does not come on during the bulb check prove out test, check the bulb and the instrument Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Figure 4-62  This oil light comes on when the key is on and the engine is off as a bulb check, and when oil pressure falls below about 3 psi.

Figure 4-63  Aim the infrared pyrometer at the thermostat housing, and ­compare the reading to the coolant temperature on the scan tool.

panel wiring. Be sure to check the manufacturer’s test procedures; the following is an example of how to test the coolant sensor and gauge. One way to test the cooling system temperature sensor is to disconnect the electrical connector. Observe the gauge; it should fall to the minimum temperature or the light should go off. Next, short the terminals together. The light should come on or the gauge should rise to maximum temperature. If it does not, check the gauge assembly and the wiring to it. On most modern vehicles, you can check the accuracy of the temperature gauge by comparing the actual coolant temperature to the temperature that the PCM is displaying. Check the actual temperature by using an infrared temperature gauge (Figure 4-63). Compare that to the temperature displayed on a scan tool. Discrepancies in the readings are usually caused by a faulty temperature sensor or wiring.

Scan Tool Diagnostics Using a Scan Tool to Check for DTCs.  A scan tool can be a very powerful and useful tool. Understanding the basics of scan tool diagnostics is necessary when diagnosing basic engine problems. The different types of scan tools and computer systems are discussed in Chapter 3. A DTC may be set in the PCM’s memory even if the MIL is not illuminated. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 4-64  Connect the scan tool cable to the DLC.

If an engine is running rough, these DTCs may help you diagnose the problem quicker, maybe even saving money on major engine repairs. For example, if there are overheating and misfire codes set in the computer, you may be able to detect a slightly blown head gasket. You may be able to repair the condition before the engine further overheated and cracked the cylinder head, and possibly damaged other expensive engine components. The first step is to connect the scan tool cable to the DLC (Figure 4-64). Most scan tools are powered by the DLC, but some are self-powered (meaning they do not have to be plugged into the DLC to power up). All OBD II DLCs have pins for battery power and ground; this powers up a scan tool. Once the scan tool is plugged into the DLC, you have to get through the menu screens by selecting the year, make, model and sometimes parts of the VIN. Turn the key to the run position (do not start the engine). Once in the menu screen you should be able to maneuver around to read the codes. The description of each code can be looked up in the service manual. The manufacturer’s service information will have a diagnostic troubleshooting tree for each code. Refer to Photo Sequence 10 for the typical steps for using a scan tool to retrieve codes. Understanding these codes and their relationship to how the engine is running is important. Depending on the code, you can then further diagnose the engine by choosing a secondary test. These secondary tests may include compression tests, cylinder leakage tests, power balance tests, and others. These tests are further explained in Chapter 7.

CASE STUDY A customer brought his 2002 Ford Focus in because the temperature gauge went into the red zone twice while driving on the highway. The technician asked him for a few more details about the events and found out that less than a minute after the temperature gauge rose into the red, it returned back to a normal temperature. The technician brought the vehicle in and inspected the coolant level and condition; it was fine. Next, she checked the water pump drive belt for damage and appropriate tension; it, too, was in good shape. Suspicious of a sticking thermostat, she started the engine while monitoring the temperature of the upper radiator hose. It did get hot when the engine temperature came up to normal. The fan also operated properly. The technician replaced the thermostat. She let the vehicle run in the shop until the fan cycled on a few times, and then she took the vehicle for a good road test. The temperature stayed in the normal range. She returned the vehicle to the customer and then followed up with a telephone call a few days later to be sure she had corrected the problem. The customer reported that all was well and that he appreciated the call.

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PHOTO SEQUENCE 10

Typical Procedure for Using a Scan Tool to Retrieve DTCs

P10-1  Roll the driver’s side window down, turn the ignition to the off position, and block the wheels (or set the parking brake).

P10-2  Select the proper scan tool data cable for the vehicle you are working on.

P10-4  Turn the ignition key to the KOEO (key on, engine off) position. Some scan tools will automatically turn on at this point; others may need to be turned on.

P10-5  Enter the model year, make, and selected VIN components into the scan tool.

P10-3  Connect the scan tool data cable to the DLC on the vehicle.

P10-6  Maneuver through the scan tool’s menu, and select “read/retrieve DTC.”

P10-7  Record the DTCs on the repair order.

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ASE-STYLE REVIEW QUESTIONS 1. Technician A says that a stuck-open oil pump relief valve can cause higher-than-normal oil pressure. Technician B says that worn oil pump gears can cause low oil pressure. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. Each of the following is a likely cause of a no-crank condition, except: A. A bad battery connection B. A faulty starter solenoid C. A loose connection at the S terminal of the starter D. A chipped starter drive gear

2. Technician A says that you can use a chemical dye and a black light to pinpoint the cause of an oil leak. Technician B says to put 80 psi of air pressure in the dipstick tube and check for leaks. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

7. A customer says his vehicle overheats only in ­traffic while idling. Technician A says that the fan may be inoperative. Technician B says that the thermostat may be stuck closed. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says that a weak battery can cause engine performance problems. Technician B says that a discharged battery is a common cause of a no-start, no-crank problem. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

8. A vehicle has contaminated coolant. Technician A says to drain and refill the coolant. Technician B says to flush the cooling system. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. To perform a check of the battery clamp connection: A. Place an ohmmeter on the battery posts. B. Use a VAT to measure current flow. C. Place voltmeter leads on the battery clamp and post while cranking the engine. D. Place the voltmeter leads on the battery post and the top of the battery. 5. While discussing proper oil change procedures, Technician A says to lift the vehicle to check for fluid leaks after restarting the vehicle. Technician B says to adjust the tire pressures and check all fluid levels. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

9. The oil pressure warning light does not come on with the key on. Technician A says that the wire on the sending unit may be disconnected. Technician B says to ground the sending unit wire, and if the light comes on, the sending unit is bad. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 10. Technician A says that the radiator should be cleaned or replaced after an engine overhaul. Technician B says to replace the water pump after an engine overhaul. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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ASE CHALLENGE QUESTIONS 1. A starter makes a grinding noise when it engages the flywheel teeth. Technician A says that it could be shimmed improperly. Technician B says that the starter drive gear could be damaged. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. A technician is performing a starter current draw test because the engine will not turn over. The test results indicate that the current draw on the starter is higher than the specification. This means that the: A. starter solenoid is bad. B. battery needs charging. C. ignition switch is bad. D. engine may be hydrostatically locked. 3. A cooling system is pressurized with a pressure tester to locate a leak. After 15 minutes, the tester gauge has dropped from 15 psi to 5 psi, and there are no visible leaks in the engine compartment. Technician A says that the engine may have an internal head gasket leak.

Technician B says that the heater core may be leaking. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. A customer says that his oil pressure warning light comes on while the car is idling. An oil ­pressure test shows low oil pressure. Technician A says that the engine bearings may be worn. Technician B says that the oil pressure relief valve may be stuck closed. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. A coolant temperature gauge does not move from its lowest reading when the vehicle is driven. Technician A says that the coolant temperature sensor wires may be disconnected. Technician B says that the thermostat could be stuck open. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Name ______________________________________

Date __________________

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JOB SHEET

17

PERFORMING A BATTERY TEST Upon completion of this job sheet, you should be able to properly perform a battery ­capacity and conductance test. NATEF Correlation This job sheet addresses the following MLR/AST/MAST task for Electrical/Electronics Systems: B.2. Confirm proper battery capacity for vehicle application; perform battery capacity test; determine necessary action. Tools and Materials • Conductance battery tester • Capacity (load) battery tester Describe the vehicle being worked on: Year ______________________ Make _____________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following: 1. Locate the correct battery rating in the service manual.

h

2. What is the battery’s CCA? Note: The battery must be fully charged to 12.65 volts before testing. 3. Connect the battery to the capacity (load) test machine by placing the large red and black clamps on the terminals and the inductive pickup lead (amp clamp) on the negative lead (make sure that the arrow is pointing the right way).

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4. Zero the ammeter on the tester.

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5. Be prepared to observe the amperage and voltage during the test. Turn the test machine on, and draw the energy out of the battery. If this is done manually on the tester, use half of the CCA rating for 15 seconds. After the test, complete the section below. Amount of current used to test: _______________ Lowest voltage reading while testing: _______________ Is the battery good or bad? _______________ 6. Disconnect and remove the capacity (load) tester, and connect the conductance tester.

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7. Perform the battery conductance test, and report the results below. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date _________________

JOB SHEET

18

TESTING A STARTER Upon completion of this job sheet, you should be able to properly measure the current draw of a starter motor and interpret the results of the test. NATEF Correlation This job sheet addresses the following MLR/AST/MAST task for Electrical/Electronic Systems: B.1.

Perform starter current draw test; determine necessary action.

This job sheet addresses the following AST/MAST task for Electrical/Electronic Systems: C.6. Differentiate between electrical and engine mechanical problems that cause a slow crank or a no-crank condition. Tools and Materials • Battery starter tester and/or ammeter (DMM with current clamp) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________

193

Caution Most engines turn clockwise as viewed from the front (crankshaft pulley side). Some engines are the opposite (counterclockwise as viewed from the crankshaft pulley side). It is always best to check the service manual for warnings or ask your instructor.

VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following tasks: 1. Install a socket and ratchet on the crankshaft (do not use an air tool).

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2. Attempt to turn the engine over by hand. Does it turn over easily? _______________ 3. Remove the spark plugs from the engine. Attempt to turn the engine over by hand. Does it turn over easier than before? _______________ 4. Reinstall the spark plugs, and remove the socket. Now locate the starter test procedure in the service manual.

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5. Disable the ignition system or fuel-injection system to prevent the engine from starting. Briefly describe the procedure. _________________________________________________________________________ 6. Expected starter current draw is _______________ amperes. Voltage should not drop below _______________ volts. 7. Connect the starting/charging system tester cables to the vehicle. _______________

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8. Zero the ammeter on the tester. 9. Be prepared to observe the amperage when the engine begins to crank and while it is being cranked. Also, note the voltage while the engine is cranking and again after you stop cranking the engine. Initial current draw: _______________ Current draw while cranking: _______________ Voltage while cranking: _______________

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10. What is indicated by the test results? Compare test measurements with specifications. _________________________________________________________________________

Task Completed

_________________________________________________________________________ 11. Reconnect the ignition or fuel-injection system.

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12. An engine that does not turn over can be caused by a dead/bad battery, bad starter, hydraulically locked engine, or a seized engine. Explain the differences between these problems and how the tests you just performed will allow you to diagnose which one it was. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date __________________

INSPECTING THE ENGINE OIL Upon completion of this job sheet, you should be able to properly check the level and condition of the engine oil and understand improper oil conditions. Tools and Materials • Technician’s tool set • Shop rag • Bottle of new engine oil Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure 1. With the engine off, remove the oil fill cap. Describe the condition of the area inside the cap. _________________________________________________________________________ _________________________________________________________________________ 2. Now remove the engine oil dipstick. What is the level? _________________________________________________________________________ 3. Smell the oil on the engine dipstick, and compare it to the smell of new engine oil. Describe the difference. _________________________________________________________________________ 4. While wearing a set of thin rubber gloves, wipe the oil off the dipstick. Rub the oil between your fingers. Then clean your gloves and repeat the same steps with new engine oil. Describe the difference. _________________________________________________________________________ 5. What would the oil look, feel, and smell like if water (from coolant or condensation) were mixed with the oil? _________________________________________________________________________ 6. What would the oil look, feel, and smell like if it were flooded with gasoline (a condition existing because the fuel management ran the engine with a rich fuel/air mixture)? _________________________________________________________________________ 7. What is your diagnosis of the oil based on your inspection of the level, condition, smell, and feel? _________________________________________________________________________ _________________________________________________________________________ 8. Check the service information for technical service bulletins related to oil consumption, oil leakage, oil pressure, and oil condition. Describe what you found and if this relates to the vehicle and engine you are working with. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

19

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Chapter 4

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

197

JOB SHEET

20

PERFORMING AN OIL AND FILTER CHANGE Upon completion of this job sheet, you should be able to properly perform an oil and filter change. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.10.

Perform engine oil and filter change.

This job sheet addresses the following MLR task for Engine Repair: D.5.

Perform engine oil and filter change.

Tools and Materials • Technician’s tool set • Shop rag • Correct type of engine oil • Service manual • Oil filter wrench • Used oil container • Torque wrench Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Follow the instructions below to complete the oil and filter change. 1. Pull the oil fill level indicator (dipstick), and note the level and condition of the oil. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What are the API and SAE ratings for the oil you are going to use (consult the service manual for the correct information)? _________________________________________________________________________ _________________________________________________________________________ 3. Warm the engine to operating temperature. The oil will flow faster when the drain plug is removed.

h

4. Properly raise the vehicle on a lift.

h

5. Place the used oil container (or catch basin) under the drain plug. Remove the drain plug, and let the oil flow into the container. You may have to adjust the position of the container because the flow rate and position will change as more oil flows out of the engine.

h

6. Now remove the oil filter. You may have to use a special wrench or remove some panels. Make sure all of the oil flows into the used oil container.

h

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Task Completed 7. Look at the oil filter mounting surface on the engine. Was the old oil filter rubber gasket removed with the old oil filter? _________________________________________________________________________ 8. Describe what could happen if the old oil filter gasket is not removed. _________________________________________________________________________ _________________________________________________________________________ 9. Check the condition of the drain plug. Are the threads or the gasket damaged? _________________________________________________________________________ 10. Locate the new oil filter, and use new engine oil to lightly lubricate the rubber gasket.

h

Compare it to the old one to make sure it is the correct fit. 11. If there is a manufacturer’s specification to tighten the oil filter, then use it. Otherwise, refer to the oil filter installation instructions on the box it came in or use the accepted industry standard of tightening it 1/2 to 1 full turn past the contact point.

h

This will allow for the gasket to remain sealed until the next oil change. 12. Install the oil drain plug, and tighten it to the manufacturer’s torque specification.

h

13. Lower the vehicle, and refill the engine with the correct amount of oil.

h

14. Pull the oil fill level indicator (dipstick), and check the oil level. Add oil if needed.

h

15. Start the engine. Check to make sure that oil pressure builds immediately (or the oil light goes off ).

h

16. Check under the car. Are there any major oil leaks? _________________________________________________________________________ 17. Turn the engine off, wait for 30 seconds, and check the oil level on the dipstick. Add if needed.

h

18. Dispose of the used oil and oil filter properly.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

OIL CHANGE REMINDER/INDICATOR RESET Upon completion of this job sheet, you should be able to properly reset the oil change reminder/indicator. Tools and Materials • Technician’s tool set • Scan tool (if needed) • Oil reset specialty scan tool (if needed) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure 1. Using the service manual or the owner’s manual, describe the steps needed to reset the oil change reminder/indicator. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Does the vehicle require any special tools or removal of any covers? _________________________________________________________________________ _________________________________________________________________________ 3. Perform the steps as outlined in step 1. What happened? Did the light go out? Did the “oil life remaining” light reset to 100 percent? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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JOB SHEET

21

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

201

JOB SHEET

22

OIL PUMP INSPECTION AND MEASUREMENT Upon completion of this job sheet, you should be able to properly inspect and measure an oil pump. Tools and Materials • Technician’s tool set • Service manual • Feeler gauge set • Micrometer set • Dial caliper • Oil pump removed from an engine Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Remove, disassemble, and draw the oil pump and its parts in the space below.

2. What type of oil pump is it (gear, rotor, etc.)? _________________________________________________________________________ 3. Inspect the various parts of the oil pump. Do any of the parts show signs of wear or damage? 4. Each manufacturer uses a different method for measuring the oil pump. Using the service manual, look up all the measurements and specifications that you will need.

h

5. Measure the oil pump, and compare against the specifications. Use the chart below as a guide to measure the type of pump you have. For gear oil pumps, measure the following: Gear-to-gear clearance ______________________________________________________ Gear-to-gear specification ___________________________________________________ Gear-to-housing clearance ___________________________________________________ Gear-to-housing specification ________________________________________________ For rotor oil pumps, measure the following: Gear-to-rotor clearance _____________________________________________________ Gear-to-rotor specification __________________________________________________ Rotor-to-housing clearance ___________________________________________________ Rotor-to-housing specification ________________________________________________

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For internal/external oil pumps, measure the following: Gear-to-gear clearance ______________________________________________________ Gear-to-gear specification ___________________________________________________ Gear-to-crescent clearance ___________________________________________________ Gear-to-crescent specification ________________________________________________ Gear-to-housing clearance ___________________________________________________ Gear-to-housing specification ________________________________________________ 6. Based on your measurements and inspection, has the oil pump caused any problems with oil pressure, and is it reusable? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

203

JOB SHEET

23

OIL PRESSURE TESTING Upon completion of this job sheet, you should be able to properly perform an oil pressure test and interpret the test results. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.9.

Perform oil pressure tests; determine necessary action.

Tools and Materials • Oil pressure gauge • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following: 1. Using the service manual, locate the oil pressure specifications. Record the specifications below. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What is the current oil level? FULL LOW OVERFULL If low, fill to proper level. If overfull, drain the oil to the proper level. Check for gas or coolant in the oil.

h

Note: Be sure the proper dipstick is installed. 3. Does the oil smell funny or feel thinner than normal? _________________________________________________________________________ 4. Remove the oil pressure sending unit from the engine.

h

5. Use the required adapters to connect the oil pressure test gauge to the engine properly.

h

6. Start the engine, and observe the gauge as the engine is idling; record your reading. _________________________________________________________________________ 7. Record the gauge reading after the engine reaches normal operating temperatures. _________________________________________________________________________ 8. If oil pressure is present, increase the engine speed to 2,000 rpm, and record the oil pressure. _________________________________________________________________________

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Task Completed 9. Snap the throttle to wide open (only for a second). What happens to the oil pressure? _________________________________________________________________________ 10. Shut off the engine, and compare test results to specifications. What are your recommendations? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 11. Remove the test gauge, and reinstall the oil pressure sending unit. Consult the service manual; you may have to put a thread sealant on it.

h

12. Start the engine, and look for leaks from the sending unit. Shut the engine off.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

205

JOB SHEET

24

OIL LEAK DIAGNOSIS Upon completion of this job sheet, you should be able to properly determine the location of oil leaks and recommend proper repairs. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: A.4. Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. D.11.

Inspect auxiliary oil coolers; determine necessary action.

This job sheet addresses the following AST/MAST task for Engine Repair: A.3. Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. Tools and Materials • Oil leak dye and light • Air blow gun with rubber tip • Rubber tube and hose clamps to fit dipstick Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following tasks: 1. Check the engine oil level, and correct to proper level if needed.

h

2. Perform a visual inspection of the engine. Record any suspect areas you find.

h

3. Add the oil leak dye to the engine oil. Start the engine, and let it idle for 5 minutes.

h

4. Turn the engine off, and use the light to locate any dye that may have leaked out. You will have to raise the vehicle on a lift to fully check every possible area for a leak.

h

5. Describe the areas where you are most likely to see the oil leak.

h

6. Lower the vehicle and install a rubber tube with hose clamps on the dipstick. Use shop air at low pressure to pressurize the crankcase. Be very careful not to use too much air pressure or a small leak will turn into a big leak.

h

7. Lift the vehicle up again, and check for leaks.

h

8. Locate and inspect any auxiliary oil coolers. Are they leaking? _________________________________________________________________________ 9. Lower the vehicle, and describe your test results and recommendations.

h

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Chapter 4

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

207

JOB SHEET

25

TESTING AN OIL PRESSURE SWITCH/SENSOR AND CIRCUIT Upon completion of this job sheet, you should be able to properly test an oil pressure sensor and switch. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: D.12.

Inspect, test, and replace oil temperature and pressure switches and sensors.

A.3.

Verify operation of the instrument panel engine warning indicators.

This job sheet addresses the following MLR task for Engine Repair: A.2.

Verify operation of the instrument panel engine warning indicators.

Tools and Materials • Service manual • Technician’s tool set • Digital multimeter (DMM) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following: 1. Check the level and condition of the engine oil. If the oil level is low, add oil as needed. Change the oil and oil filter if necessary.

h

2. To verify that the problem is electrical, you should first perform an oil pressure test. This will rule out the possibility that the problem is with the engine.

h

Note: Steps 3–10 are for diagnosing a vehicle with an oil pressure switch. 3. How much engine oil pressure does it take to turn the dash warning light off? _________________________________________________________________________ 4. Is the oil pressure switch a normally open or normally closed switch? _________________________________________________________________________ 5. Turn the key to the on position. With the engine off, does the warning light come on? _________________________________________________________________________ 6. If the warning light does come on, does this mean that the circuit is working? _________________________________________________________________________ 7. Disconnect the oil pressure switch connector and start the engine. What happened to the light? _________________________________________________________________________ 8. Should that have happened? _________________________________________________________________________

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9. Turn the engine off, but leave the key in the on position, and check for voltage at the wire connector terminal (coming from the dash). Is there voltage present? _________________________________________________________________________

Task Completed

10. Based on your testing, what can you conclude about the oil pressure switch? _________________________________________________________________________ _________________________________________________________________________ Note: Steps 11–15 are for diagnosing a vehicle with an oil pressure sensor. 11. Describe how the sensor’s resistance readings relate to the engine oil pressure readings. _________________________________________________________________________ _________________________________________________________________________ 12. With the engine running, carefully measure the sensor’s resistance at idle. _________________________________________________________________________ 13. With the engine running, carefully measure the sensor’s resistance at 2,500 rpm. _________________________________________________________________________ 14. Describe if the resistance readings are within specifications, and if the sensor could be the possible cause of an incorrect dash reading. _________________________________________________________________________ _________________________________________________________________________ 15. According to the sensor’s resistance range, what should happen to the gauge when you disconnect the wire from the sensor? _________________________________________________________________________ 16. Disconnect the sensor’s connector, and verify your answer.

h

17. Explain why the gauge moved when the sensor was disconnected. _________________________________________________________________________ _________________________________________________________________________ 18. Based on your test results, what is your repair recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

209

JOB SHEET

26

TEST, DRAIN, AND REFILL COOLANT Upon completion of this job sheet, you should be able to properly perform test, drain, and refill the coolant and recommend repairs. NATEF Correlation This job sheet addresses the following MLR/AST/MAST task for Engine Repair: D.4. Inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required. Tools and Materials • Technician’s tool set • Coolant test strips • Refractometer • Voltmeter • Coolant recovery container Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following: 1. Place a shop rag over the radiator cap, and using caution, slowly open the cap.

h

2. Place a coolant test strip in the coolant, and quickly pull it out. Shake the strip for 30 seconds, and compare it to the bottle’s rating system. Describe what you found. _________________________________________________________________________ _________________________________________________________________________ 3. Using the eyedropper from the refractometer kit, place a small drop of coolant on the lens of the refractometer. Hold it up to some light, and describe what you found. _________________________________________________________________________ _________________________________________________________________________ 4. Set the voltmeter to read DC volts. Connect the test leads to the meter. Place the negative lead on the battery negative terminal and the positive lead in the coolant itself (do not touch the radiator or any other solid pieces). Describe your findings. _________________________________________________________________________ _________________________________________________________________________ 5. Leave the radiator cap off, and raise the vehicle up.

h

6. Position the coolant catch basin under the radiator drain valve (petcock).

h

7. Loose the radiator drain valve, let the coolant drain, and then remove the valve.

h

8. After the coolant is done draining, install the drain valve and lower the vehicle.

h

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9. What type of coolant and mixture should this vehicle use? _________________________________________________________________________

Task Completed

10. Add the proper coolant type and mixture to the system until it is full. You may need to add more fluid after a few minutes.

h

11. Start the engine with the cap off, and let it run for a few minutes. Add coolant as needed to the radiator or reservoir.

h

12. Install the coolant cap correctly, and start the engine again. Locate the cooling system bleeders (if applicable). Describe where they are located. _________________________________________________________________________ 13. With the engine running and at operating temperature, slowly open the bleeder screw. Keep it open until only liquid comes out (no bubbles).

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

211

JOB SHEET

27

RADIATOR REPLACEMENT Upon completion of this job sheet, you should be able to properly replace a radiator. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.6.

Remove and replace radiator.

Tools and Materials • Technician’s tool set • Coolant recovery container Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following tasks: 1. Let the engine cool down. Then carefully remove the radiator cap (or coolant recovery cap).

h

2. Open the radiator petcock, and drain the coolant from the radiator into the catch basin.

h

3. Remove the upper and lower radiator hoses, the fan shroud, and any electrical connections on the radiator (which may include the electrical fan).

h

4. Remove the transmission cooler lines with a flare wrench (if applicable).

h

5. Remove the radiator brackets, and lift the radiator out.

h

6. Before reinstalling the radiator, check the mounts and surrounding areas for cracks, rust, and damage. If you are installing a new radiator, check the size of the hoses, petcock locations, and other dimensions to make sure it fits.

h

7. Reinstall the radiator in the reverse process of removal.

h

8. Add the proper coolant type and mixture to the system until it is full. You may need to add more fluid after a few minutes.

h

9. Start the engine with the cap off, and let it run for a few minutes. Add coolant as needed to the radiator or reservoir.

h

h

10. Install the coolant cap correctly, and start the engine again. Locate the cooling system bleeders (if applicable). Describe where they are located. _________________________________________________________________________ 11. With the engine running and at operating temperature, slowly open the bleeder screw. Keep it open until only liquid comes out (no bubbles).

h

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Chapter 4

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

213

JOB SHEET

28

DIAGNOSING COOLING SYSTEM LEAKS Upon completion of this job sheet, you should be able to determine the location of coolant leaks properly and recommend proper repairs. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: D.1. Perform cooling system pressure and dye tests to identify leaks; check coolant condition and level, inspect and test radiator, pressure cap, coolant recovery tank, and heater core; determine necessary action. A.4.  Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. This job sheet addresses the following MLR tasks for Engine Repair: D.1. Perform cooling system pressure and dye tests to identify leaks; check coolant condition and level, inspect and test radiator, pressure cap, coolant recovery tank, and heater core; determine necessary action. A.3. Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. Tools and Materials • Technician’s tool set • Cooling system pressure tester Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following: 1. Check the coolant level, and correct to proper level if needed.

h

2. Visually inspect the engine and cooling system for indications of a leak. Record your findings. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Using the proper service manual, locate the cooling system pressure specifications and record them. _________________________________________________________________________ 4. Remove the radiator cap (cold engine only) and inspect it. _________________________________________________________________________ 5. Install the radiator cap to the pressure tester, and pump the pressure to the minimum holding pressure. Does the cap pass the test?

h Yes  h No

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Chapter 4

Task Completed 6. Install the pressure tester to the radiator fill neck, and pump the pressure to specifications. Does the system hold the pressure for 15 minutes?

h Yes  h No

If the pressure drops below specifications, visually inspect all areas for external leaks. Remove the dipstick, and look for evidence of an internal leak. What are the results of your inspections? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 7. Apply 5 psi of pressure to the radiator, and start the engine. With the engine idling, observe the pressure gauge. Does the reading indicate a cylinder head gasket leak?

h Yes  h No

8. If the cause of the leak is not found, determine what method you are going to use to locate the coolant leak (dye, infrared exhaust gas analyzer, etc.).

h

9. Briefly describe the procedure you have chosen to use. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Check the condition of the coolant. Does the condition of the coolant relate to any problems you found with the system? _________________________________________________________________________ 11. Based on your test results, what is your repair recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

REPLACING A WATER PUMP Upon completion of this job sheet, you should be able to properly replace a water pump and drain and refill the cooling system. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.5.

Inspect, remove, and replace water pump.

Tools and Materials • Technician’s tool set • Coolant recovery container Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Locate the procedure to remove and replace the water pump in the service information. Briefly outline the steps. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Loosen the radiator petcock to drain the coolant into a drain pan. How do you handle the used coolant? _________________________________________________________________________ _________________________________________________________________________ 3. Remove the lower radiator hose, and inspect it. Remove the water pump drive belt, and inspect it. Describe the results of your inspections. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Follow the manufacturer’s procedure to remove the water pump. Clean the engine block mating surface thoroughly. Install the new gasket, apply sealant if recommended, and torque the new water pump into place. Recommended sealant: _________________________________________________________________________ Water pump bolts’ torque specification: _________________________________________________________________________ Reassemble as needed. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

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5. Install the water pump drive belt, and adjust the tension as needed. Describe the procedure to adjust the tension. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Refill the cooling system, bleed it as required, and pressure test the system for leaks. Results: _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

217

JOB SHEET

30

DIAGNOSING AND REPLACING A THERMOSTAT Upon completion of this job sheet, you should be able to properly diagnose and replace a thermostat. The thermostat is often the most replaced component in the cooling system. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: D.2.

Identify causes of engine overheating.

D.7.

Remove, inspect, and replace thermostat and gasket/seal.

This job sheet addresses the following MLR task for Engine Repair: D.3.

Remove, inspect, and replace thermostat and gasket/seal.

Tools and Materials • Technician’s tool set • Coolant recovery container • Infrared temperature gun Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following: 1. Find the correct operating temperature using the service manual. _________________________________________________________________________ 2. Let the engine warm up to operating temperature, and check the temperature of the engine using the dash gauge and infrared gun, or a scan tool.

h

3. Check the operation of the thermostat by watching the scan tool data or using the IR gun on the upper radiator hose. Is the thermostat opening and closing properly? _________________________________________________________________________ 4. Let the engine cool down; then carefully remove the radiator cap (or coolant recovery reservoir cap).

h

5. Open the radiator petcock, and drain the coolant from the radiator into the catch basin until the level of coolant is below the thermostat.

h

6. Remove the correct radiator hose and the thermostat housing.

h

7. Remove the thermostat. How does it look? _________________________________________________________________________ 8. Clean the gasket mating surface.

h

9. After cleaning the thermostat housing and gasket surface, install the new thermostat and new gasket (or sealing ring).

h

10. Reinstall the housing and radiator hose. Torque the thermostat housing bolts to the manufacturer’s specification.

h

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Chapter 4

11. Refill the cooling system, bleed it as required, and pressure test the system for leaks. Results: _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

219

JOB SHEET

31

TESTING A COOLANT TEMPERATURE SWITCH/SENSOR CIRCUIT Upon completion of this job sheet, you should be able to properly test a coolant temperature sensor and switch. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.3.

Verify operation of the instrument panel engine warning indicators.

This job sheet addresses the following MLR task for Engine Repair: A.2.

Verify operation of the instrument panel engine warning indicators.

Tools and Materials • Service manual • Technician’s tool set • Digital multimeter (DMM) • IR temperature gun • Scan tool Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following: 1. Check the level and condition of the engine coolant. If the coolant level is low, add as needed.

h

2. Where is the coolant temperature switch and/or sensor located? _________________________________________________________________________ Note: There may be more than one of these sensors. Try to determine with your instructor which one to use. 3. To verify that the problem is electrical, you should first determine if the engine is heating and cooling properly. To determine this, start with the engine cold (and not running). Using the temperature gun, aim for a spot on the engine as close to the sensor as you can.

h

4. What is the temperature? _________________________________________________________________________ 5. Does the dash gauge or indicator reflect a similar temperature? _________________________________________________________________________ Note: Read the instruction manual for using the temperature gun. The distance at which it is held from the object you are measuring will make a difference in the reading.

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Chapter 4

6. Connect the scan tool to the vehicle, and check the PID for the engine temperature.

Task Completed

What does it read? _________________________________________________________________________ 7. Now disconnect the sensor/switch, and measure the resistance of it with the DMM. _________________________________________________________________________ 8. Reconnect the wires, and let the engine run until it gets warmer (don’t let it overheat). Again, measure the temperature on the engine as close to the sensor as you can.

h

9. What is the temperature? _________________________________________________________________________ 10. Does the dash gauge or indicator reflect a similar temperature? _________________________________________________________________________ 11. Connect the scan tool to the vehicle and check the PID for the engine temperature. What does it read? _________________________________________________________________________ 12. Turn the engine off; disconnect the sensor/switch and measure the resistance of it with the DMM. _________________________________________________________________________ 13. If the engine uses a switch, the switch will close or open when the temperature reaches a predetermined temperature (usually when the engine will overheat). A sensor will change its resistance with an increase or decrease in temperature. Go through the service manual, and describe how the sensor/switch works on the engine you are working with. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 14. Now disconnect the switch, and turn the engine on. Describe what the dash light/ gauge does/reads and what the scan tool PID reads. _________________________________________________________________________ 15. Based on your testing and inspection, describe what you found and any problems with the vehicle that need attention.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

221

JOB SHEET

32

ENGINE BELT AND SYSTEM INSPECTION Upon completion of this job sheet, you should be able to properly diagnose and inspect the engine belts, pulleys, and tensioners. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.3. Inspect, replace, and adjust drive belts, tensioners, and pulleys; check pulley and belt alignment. This job sheet addresses the following MLR task for Engine Repair: D.2. Inspect, replace, and adjust drive belts, tensioners, and pulleys; check pulley and belt alignment. Tools and Materials • Technician’s tool set • Serpentine belt tensioner tool • Cricket belt tensioner tool • Pulley alignment laser (or straightedge) Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Describe the method outlined in the service manual (or on the under-hood label) for removing the tension on the engine belt. _________________________________________________________________________ _________________________________________________________________________ 2. Using the proper tools, release the tension on the belt and remove it.

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3. If the system has an automatic tensioner, attempt to move it back and forth. Does it move smoothly and appear to be in reusable condition? _________________________________________________________________________ 4. Check the belt. If it has more than three cracks in 3 inches, it should be replaced. How does the belt you are working with look? _________________________________________________________________________ 5. If the belt you are working with is an EPDM belt, use the special orange Gates belt measuring gauge to check the belt rubber depth. What did you find? _________________________________________________________________________ 6. Using a pulley alignment laser (or a straightedge), check the pulleys for alignment. Also, look at the belt for signs that the pulleys are misaligned (frayed on the edges). Describe your findings. _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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7. Rotate and spin each pulley on the system. Describe your findings. _________________________________________________________________________

Task Completed

_________________________________________________________________________ 8. Reinstall the old belt if it is reusable, or install a new belt.

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Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

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JOB SHEET

33

COOLING SYSTEM FAN INSPECTION Upon completion of this job sheet, you should be able to properly diagnose and inspect the engine cooling fan (electrical or mechanical). NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: D.8. Inspect and test fan(s) (electrical or mechanical), fan clutch, fan shroud, and air dams. Tools and Materials • Technician’s tool set • Digital multimeter (DMM) • Scan tool • Infrared temperature gun Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following: 1. Visually inspect the air shroud and air dams. Do they appear to be cracked or damaged? _________________________________________________________________________ 2. If you have a fan clutch, visually inspect it for any signs of leakage and blade damage. Describe your findings. _________________________________________________________________________ 3. Start the engine and let it warm up. Does the fan clutch turn? _________________________________________________________________________ 4. Increase the engine speed to 2,500 rpm. Does the fan change speed or sound? _________________________________________________________________________ 5. For vehicles with electric fans, visually inspect the fan and its electrical connections.

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6. Turn the engine on, and let it warm up. Using the IR gun, a scan tool, or the dash gauge, watch the temperature. What temperature should the fan come on at? _________________________________________________________________________ 7. Turn the engine off, and disconnect the electrical connector to the electric fan.

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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8. Using the DMM, test the fan for continuity (resistance) by placing both test leads on the two motor connector terminals. What is your reading? _________________________________________________________________________ 9. Based on your testing and inspections, what are your recommendations? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing and Servicing Engine Operating Systems

Name ______________________________________

Date __________________

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JOB SHEET

34

USING A SCAN TOOL TO RETRIEVE ENGINE CODES Upon completion of this job sheet, you should be able to properly use a scan tool to retrieve DTCs on an OBD vehicle. Tools and Materials • Scan tool Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following: 1. Apply the parking brake or block the drive wheels, and roll the driver’s side window down.

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2. Describe the manufacturer, model, and version of the scan tool that you can use for this vehicle. _________________________________________________________________________ 3. Is the scan tool you are using a generic or manufacturer-specific scan tool? _________________________________________________________________________ 4. Make sure the key is off, and connect the scan tool to the diagnostic link connector.

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5. Turn the ignition to the run (no-start) position, and maneuver through the scan tool menu to retrieve the codes. List all the codes here. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Describe the process for clearing the codes (do not actually clear them). _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 5

DIAGNOSING ENGINE PERFORMANCE CONCERNS

Upon completion of this chapter, you should understand and be able to describe: ■■

■■

■■ ■■

■■ ■■

■■

How to replace and evaluate the older type of spark plugs, with nickel alloy steel electrodes every 30,000–60,000 miles, and the newer, platinum spark plugs that have a longer service interval, typically 60,000–100,000 miles. Why it is important to keep spark plugs in order when removing them so you can trace any problems with the plug to the correct cylinder. How to diagnose engine operating ­concerns by “reading” the spark plugs. How to use a power balance test to find a cylinder that is not contributing equally to the power of the engine. The reasons for blue smoke being ­emitted from the tailpipe. How to identify black smoke caused by too rich an air-fuel mixture or incomplete combustion. The causes of excessive oil consumption.

■■

How to use a cranking compression test to assess the condition of the rings, ­pistons, valves, and head gasket(s).

■■

How to use a wet compression test to help determine whether low ­readings are caused by worn rings or by a burned valve or piston. How to perform a running compression test to help you evaluate the condition of the valvetrain. How to use a cylinder leakage test to pinpoint the cause of improper ­combustion chamber sealing and ­interpret the test results. How to diagnose engine problems from intake manifold vacuum readings. How to listen closely to engine noises to help you correctly diagnose engine problems. Engine noises, their possible causes, and methods of diagnosis.

■■

■■

■■ ■■

■■

Terms To Know Bell housing Bottom-end knock Chemical combustion tester Compression test Crankshaft end play

Cylinder leakage test Detonation Fuel pressure regulator Knock sensor (KS) Oxygen sensor (O2S) Piston slap

Power balance testing Preignition Thrust bearing Valvetrain clatter

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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INTRODUCTION You should spend adequate time diagnosing the causes of engine performance problems before jumping into engine mechanical repairs. In this chapter you will learn several methods of determining why an engine is performing poorly. Some of these will lead you to determine that the engine requires engine mechanical repairs or even engine overhaul or replacement. Others will lead you to a less dramatic repair that may cost the customer much less. You need to isolate the cause of a performance problem as much as possible to help guide your repairs and ensure that you are able to make a successful repair on the first try.

SPARK PLUG EVALUATION AND POWER BALANCE TESTING A power balance test evaluates approximately how much each cylinder is contributing to the overall engine power. It is used to help identify a weak cylinder.

Spark plug reading and power balance testing are two methods you will use to gather information about how the engine is operating. You may use these tests during a routine tune-up, when there is a drivability concern, and as part of gathering information about an engine mechanical failure. Spark plugs can help identify if one or more cylinders are acting up or if all cylinders are affected. They can also help guide your diagnosis toward a fuel, ignition, or mechanical issue, for example. Similarly, a power balance test can determine how much each cylinder is contributing and pick out the malfunctioning cylinder(s).

SPARK PLUGS The spark plug must be in good condition to allow the spark to jump the gap. If the electrodes are worn rounded or covered with oil or gas, or if the gap is too large, the spark will not be strong enough to ignite a flame front, if it sparks at all. Spark plugs are generally one of two basic types: the older type plug with nickel alloy steel electrodes and the newer, more common platinum tip electrode plugs. Most new vehicles use the platinum plugs as original equipment (Figure 5-1). The platinum tip plugs have a service interval of 60,000 miles or longer. The older style plugs generally must be replaced every 30,000 miles.

Figure 5-1  A platinum tip spark plug. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Many times customers do not bring their cars in for service until there is a drivability concern. Spark plugs have a high failure rate; check them early on in your diagnosis. As a spark plug wears, the gap between the electrodes becomes so wide it may not allow the spark to jump the gap. This can cause partial or total misfiring on that cylinder. Ignition misfire is usually noticeable at low rpm under heavy acceleration. The engine may buck and shudder when the cylinder(s) misfires. It is often difficult to see wear on a platinum plug; the electrodes are small and do not show much visible degradation. Many technicians will replace rather than inspect and reinstall platinum plugs with more than 30,000 miles on them. Given today’s labor rates, this is often more cost-effective for the consumer. If the engine is running poorly and you have the spark plugs out, it may be wise to perform a compression test, which is described later in this chapter.

Spark Plug Removal and Installation While spark plug removal is a very common task in the automotive repair shop, it is not always a simple one. Many times you will have to disassemble parts of the engine to access the spark plugs. Some vehicles require you to remove an intake plenum, engine mount, or remove the turbocharger just to access the plugs. Every time you replace a set of spark plugs, you want to be sure you do not damage the plugs or the threads while installing them. Always be sure to replace the whole set of plugs. If one has failed, the others are likely not far behind. If access to the plugs is not simple, read through the service information to pick up any steps that will make the job easier. This task often requires a universal joint and an assortment of extensions (Figure 5-2). Blow away any sand and grit from around the spark plug holes before removing the plugs, to prevent sand and grit from falling into the cylinder head. Remove all plugs, and keep them in order so you can evaluate the condition of each plug and correlate it to the correct cylinder. Keep the spark plug wires (if applicable) organized, so you return them to their correct positions. Carefully inspect the ends of the plug wires. They can easily be damaged during removal and may require replacement. Also look closely at the plug wires for signs of electrical leakage or arcing to a ground path. If the wire’s insulation is damaged, you can often see a light gray or white residue on the wire where the high voltage arcs to a ground—on the valve cover, for example, rather than across the spark plug gap.

Caution Do not remove spark plugs from a hot aluminum cylinder head; this can easily damage the threads in the head. Allow the engine to cool down adequately before removal of spark plugs.

Caution Never use air tools to remove or install spark plugs. It takes a lot longer to repair a spark plug hole than it does to loosen plugs with a ratchet!

Figure 5-2  This spark plug is readily accessible; not every engine makes it this easy. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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CUSTOMER CARE  In one semester three students have come to me with a ­misfiring problem. In each case, they had recently replaced spark plugs using a popular, low-cost brand of spark plugs. Installing higher-quality or OEM spark plugs repaired each of the three late-model vehicles. Use OEM or high-quality spark plugs on your customers’ cars to prevent comebacks.

Check the spark plug gap before installing the new set of plugs. Sometimes the gap gets closed if the plugs have been dropped. Note that some platinum spark plugs do not have adjustable gaps. Clean the area around the spark plug hole. If you get grease on the electrodes during installation, you will likely wind up with a misfiring spark plug. Install the new plugs by hand; do not use air tools. If you can’t reach the plug itself, turn it in a few turns using only the extension.

Some manufacturers recommend coating the plug’s threads with an antiseize lubricant before installing them into the engine. Finish tightening the plug to the correct torque specification using a torque wrench. After your work is complete, always give the vehicle a thorough road test to be sure the engine runs perfectly.

SERVICE TIP  When the plugs are very difficult to reach, it is helpful to put a piece of vacuum line on the end of the spark plug. This flexible connection allows you to reach the spark plug hole. Turn the plug in a few turns using the end of the vacuum line. If you start to cross thread the plug, the vacuum line will spin on the spark plug and prevent thread damage.

Spark plug breakage can occur during removal (Figure 5-3). Breakage is not uncommon on certain models. Researching technical service bulletins (TSBs) before beginning can be helpful. A common recommended procedure is to blow out the spark plug tubes after removing the coils or plug wires. While the engine temperature is warm (not hot or cold), loosen the spark plugs no more than ⅛ to ¼ of a turn. Spray carburetor cleaner around each plug letting them soak at least 15 minutes. Lastly, while loosening the plugs, work them back and forth slowly to get them out. Note: Some techs soak the plugs overnight before attempting to remove them. Tools are available for broken spark plug removal for specific models. Spark plug thread inserts are also available to replace stripped-out threads.

Figure 5-3  This spark plug broke during removal. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Spark Plug Reading Each spark plug can tell you a story about what is occurring in the cylinder. During a routine service, you can use this information to help determine if the engine is mechanically sound. If one spark plug comes out caked with oil deposits from oil leaking past the rings or valve seals, you will be able to let the customer know that the engine is in need of more serious work. When you are performing a drivability diagnosis, the spark plugs can help guide your diagnosis. If one spark plug was wet with fuel, you would first confirm that the ignition system is delivering adequate spark to the plug. And whenever you are trying to narrow down the cause of an engine failure, analyze the spark plugs as part of your pre-teardown investigation. The more information you have going into the job, the more confident you can be that you will find the real cause of the problem. Spark plugs that are wearing normally should show a light tan to almost white color on the electrodes, with no deposits (Figure 5-4). The electrodes should be square, and the gap should be at or near at the specified measurement. You will see plugs that have a red or orange tint on them. This is the result of fuel additives found in certain fuels or in fuel system cleaning additives. A spark plug that has many miles on it but is wearing normally will still be light tan in color. There should be only very light deposits, if any, on the plug (Figure 5-5). On nonplatinum plugs, you will be able to see that the corners of the electrodes are rounded. The gap will usually be wider than specified. On platinum plugs, the tip may look brand new even when the plug is not firing well. Often you will have to judge wear by the miles since the last change. If the plug is not firing at all, it will be gas-soaked and smell like fuel.

231

Caution No technician has a torque wrench built into his elbow, no matter how adamantly he insists he can torque something properly. Spark plug torque specifications are very light on many new engines, and a stiff elbow can easily strip the spark plug threads on an aluminum cylinder head.

Figure 5-4  This spark plug is wearing nicely; it has no deposits and is a light tan color.

Figure 5-5  Notice the wide gap and rounded electrodes on these worn spark plugs. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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CUSTOMER CARE  Some spark plugs are advertised to last for over 100,000 miles. This doesn’t guarantee they’ll last that long; these platinum plugs have a high failure rate over 50,000 miles and often become welded into the cylinder head by 75,000 miles. A 60,000-mile service interval is a reasonable compromise that is likely to serve the customer better.

Fuel-fouled plugs will be wet with gas when you remove them from the engine. They will smell like fuel and may have a varnish on the ceramic insulator from heated fuel. The most common cause of this is inadequate spark, though a leaking fuel injector will also flood the plug. If the valves are burned or the compression rings are badly worn, the engine may lack adequate compression to make the air-fuel mixture combustible. A ­compression check will either verify or rule out that problem. SERVICE TIP  The classic symptoms of an ignition misfire are bucking and hesitation on hard acceleration. A fuel-related problem, such as a restricted fuel filter, is more likely to cause a steady lack of power as engine speed slowly increases.

When a vehicle is burning oil, the spark plugs will develop tan to dark-tan deposits on and around the electrode. As the oil is heated during combustion, it bakes onto the plug, leaving a residue. You will have to rule out any other possible causes of oil consumption, such as a plugged PCV system, badly worn valve seals, or a faulty turbocharger, but this is usually a telltale sign that the engine is mechanically worn. If you find this problem during a routine service, it is important to warn the customer about the failing condition of his engine. If the oil is wet and thick on the plug, look for a cause of heavy oil leakage into the cylinder. On rare occasions, a head gasket will crack between an oil passage and the cylinder, allowing oil into just one cylinder. This can cause an oil-soaked plug. Similarly, a hole blown in a piston can cover a plug with oil, but you will have other indicators of a serious mechanical failure. Black-colored, soot-covered spark plugs are found when the air-fuel mixture is too rich. This means there is too much fuel and not enough air. This can be caused by something as simple as a plugged air filter or as involved in the powertrain control system as an inaccurate engine coolant temperature (ECT) sensor (Figure 5-6). An engine that does not have good compression can also create carbon because combustion will not be

Engine coolant temperature sensor

Figure 5-6  A faulty engine coolant temperature sensor can cause the engine to run rich. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

complete. The key is to notice the condition. Locate the cause before considering a maintenance service complete. Write down your observations if you are evaluating an engine for serious mechanical repairs. Blistered or overheated spark plugs are a sign of potentially serious trouble in the combustion chamber. The porcelain insulator around the center electrode will actually have blisters in it, or there may be pieces of metal welded onto the electrode. It is possible that the wrong spark plugs were installed in the engine. Otherwise it is likely that pinging or detonation is occurring. If there is no engine damage yet, it is critical to find the cause of the problem before returning the vehicle to the customer. If you find this as you are diagnosing an engine mechanical failure, it is essential to record this information and find the source of the problem during your repair work. A cooling system passage with deposits in it could be causing one corner of a combustion chamber to be getting so hot that detonation occurs. If you were to replace the damaged piston and rings but not repair the cause of the problem, the customer would be back soon with a repeat failure. Your thorough evaluation of the engine and analysis of the causes of the symptoms will ensure customer satisfaction.

POWER BALANCE TESTING On a rough-running or misfiring engine, you can perform a power balance test to identify a cylinder that is not equally contributing power to the engine. To perform the test, you disable one cylinder at a time while noting the change in engine rpm and idling condition. The more the rpm drops or the rougher the engine runs, the more the cylinder is contributing. If a cylinder is producing little or no power, the change in rpm and engine running will barely be noticeable. You must note the rpm drop quickly as the cylinder is initially disabled; today’s PCMs will boost the idle almost immediately to compensate for the drop. You will also be able to feel and see the roughness of the engine as a functional cylinder is disabled. We’ll discuss a few different methods of performing a power balance test.

Power Balance Testing Using an Engine Analyzer or Scan Tool Many engine analyzers can perform a manual or automated power balance or cylinder efficiency test. With the analyzer leads connected to the ignition system as instructed in the user’s manual, select the power balance test from the menu (Figure 5-7). The tester will automatically disable the ignition to one cylinder at a time for just a few seconds and

Figure 5-7  This engine analyzer shorts one cylinder at a time and displays the engine rpm drop. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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display the rpm drop. The analyzer disables spark in the firing order; an engine with the firing order 1-3-4-2 would be tested on cylinder number one first, then number three, number four, and number two. On some analyzers, the power balance results will be displayed in bar-graph format for easy comparison of cylinder contribution. On some vehicles, the PCM is programmed to be able to perform a power balance test. The manufacturers and some aftermarket scan tools will be able to access this test. The only hookup required is to the diagnostic link connector (DLC). Then select the power balance test from the menu system. At the prompt, the scan tool will communicate with the PCM to initiate its disabling of cylinders by shutting off injectors one by one. The rpm drop for each cylinder will be displayed after the test.

Manual Power Balance Testing Even without an engine analyzer or a capable scan tool, you can perform a power balance test. The procedure will require that you manually disable either fuel or spark to each cylinder. It is also important that you check the vehicle for diagnostic trouble codes (DTCs) after performing this test and clear the codes if any are present. You can access DTCs using a scan tool; the code can help you locate the source of the problem. If the PCM detects a misfire, it is likely to set a DTC. When the malfunction indicator light comes on, a DTC has been set. Using the menu on a scan tool, you can erase any DTCs when your testing is complete. If the fuel injector connectors are accessible you can unplug the connectors to the fuel injectors one by one while listening to and watching the engine rpm. By preventing fuel from entering the cylinder, you can momentarily disable the cylinder. This allows you to note how much the cylinder is contributing to the overall power of the engine. Another way to perform a manual power balance test on vehicles that use spark plug wires to deliver the spark to the plug, is to short the spark to ground on each cylinder in turn to test the power contribution of cylinders. You’ll need a 12-volt test light and 1½-inch pieces of vacuum hose (one per cylinder). Install all the vacuum hose pieces between the spark plug wires and the distributor cap towers or on an EI ignition system between the coil and plug wire. Attach the ground clip of the test light to a good ground. With the engine running, short out one spark plug wire at a time by touching the vacuum hose with the tip of your test light. As you ground each vacuum hose listen for a clear change in rpm and idle quality. Monitor the rpm drop on a tachometer. There will be a considerable difference if that cylinder is contributing adequate power. On coil-on-plug ignition systems each spark plug has its own coil. Locate the connector going into the coil (Figure 5-8). While the engine is running, you can briefly remove the connector to prevent the coil from firing.

Figure 5-8  Disconnect the low voltage primary wiring to the individual coils and record the rpm drop. Be sure to clear any DTCs after your testing. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

As you unplug each coil, monitor the rpm drop on a tachometer. Repeat this for each cylinder, and compare your results. This testing is very likely to trigger the malfunction indicator light (MIL) and set a diagnostic trouble code, so be sure to clear the DTCs after your testing.

Analyzing the Power Balance Test Results When an engine is running properly, each cylinder should cause very close to the same rpm drop when disabled. Cylinders that are lower by just 50 rpm should be analyzed. Look at the following results: Cyl. No. 1

Cyl. No. 3

Cyl. No. 4

Cyl. No. 2

125 rpm

150 rpm

50 rpm

125 rpm

Cylinder number four is definitely not contributing equally to the power of the engine. The rpm changed very little when it was disabled, meaning that the engine speed is barely affected by that cylinder. There could be many causes of the problem, but you now know which cylinder to investigate. The problems could relate to fuel delivery; perhaps the fuel injector was not delivering adequate fuel to support combustion. An ignition system problem, something as simple as a spark plug with a very wide gap from worn electrodes, could also cause this. A cylinder with low compression will also produce less power and be suspect during a power balance test. Compression testing and cylinder leakage testing will help you determine whether the weak cylinder has an engine mechanical problem. They can also provide information about what the specific cause may be.

235

Caution You must be careful not to disable spark for longer than 15 seconds at a time, and you must allow the engine to run on all cylinders for one minute between tests. Failure to follow these guidelines can overload the catalytic converter with raw fuel and damage it from overheating. Running a floor fan in front of the vehicle is also recommended.

EXHAUST GAS ANALYZERS Modern exhaust gas analyzers are either four- or five-gas analyzers (Figure 5-9). By looking at the quality of an engine’s exhaust, a technician can look at the effects of the ­combustion process.

Figure 5-9  A five-gas analyzer. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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If an engine is running too rich, the level of CO will be higher than normal and the oxygen will be lower. A few possible causes of a rich mixture are a faulty fuel-pressure regulator or oxygen sensor, a restricted exhaust, or low compression. An engine with an ignition misfire will emit high levels of unburned fuel in the form of hydrocarbons, and the oxygen level will also be high. Worn spark plugs or spark plug wires, or faulty coils, are common culprits causing ignition misfire. A five-gas analyzer also measures the level of oxides of nitrogen (NO x ). This pollutant is formed when combustion temperatures are too hot; it contributes to the formation of ground-level ozone, smog.

ENGINE SMOKING Engine smoking can indicate a very serious engine problem. It may also be caused by a relatively minor problem. This makes your correct diagnosis essential. Some likely causes of engine smoking and methods of diagnosis are described next. CUSTOMER CARE  A customer came in distraught, convinced that the “engine is blown” because it started blowing blue smoke out of the tailpipe. A careful check of the specific times when the smoking occurred pointed to worn valve seals. The customer was relieved to have his vehicle repaired for a fraction of engine replacement or rebuild (Figure 5-10).

Blue Smoke SERVICE TIP  Oil found in the air filter housing indicates a possible PCV system restriction, excessive engine blow-by, or a leaking turbocharger seal.

There are several possible causes of blue smoke: ■■ Worn rings or cylinders ■■ A plugged PCV system ■■ Worn valve seals or guides ■■ A blown turbocharger ■■ A leaking head gasket

Figure 5-10  Replacing these worn valve seals cured the engine smoking concern. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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237

PCV valve

Figure 5-11  Shake the PCV valve to be sure it rattles, and blow through the hose to be sure it is clear.

Obviously the difference in parts and labor to repair a PCV system, as opposed to replacing faulty rings, is dramatic. Be very careful to check each of these possible causes before disassembling or replacing an engine. A clogged or frozen PCV valve or hose can cause a tremendous amount of blue smoke to pour out of the tailpipe at all times when the engine is running. The more you accelerate, the greater the smoking. Shake the PCV valve; it should rattle (Figure 5-11). Replace it if there is any possibility that it could be faulty. Blow through the larger diameter hose attached to the PCV valve that connects to the air filter housing. If it is clogged, clean it thoroughly, and road test the vehicle again to confirm your repair. Worn valve seals will cause smoking at predictable times. At start-up after the engine has been sitting for a period, you will notice a cloud of blue smoke. This occurs because when the engine is shut off, the oil sitting under the valve cover can leak past the worn seals into the combustion chamber. When the engine starts, it burns this oil that produces blue smoke. It will clear up significantly after running for a few minutes. Once the engine is running, the oil is constantly circulating through the engine and not pooling up above the seals, so the smoke will dissipate. Also, when the engine is at idle or decelerating for a period of time, the engine vacuum is high. This can draw oil into the combustion chamber past the weak seals. When you accelerate after idling or decelerating, you may notice a puff or cloud of blue smoke. Valve seals can be replaced relatively inexpensively; the ­cylinder head does not need to be removed (Figure 5-12). A turbocharger with blown seals can produce huge clouds of smoke on acceleration. This could easily be confused with worn rings, but an engine overhaul would not cure the problem. Whenever a turbocharged engine is smoking, check the turbo seals first. After the engine cools down remove the boot on the intake side of the compressor and look for oil. If plenty of oil is sitting in the turbo housing and the boot, replace the faulty turbocharger. By hand check the impeller for excessive up and down movement to help confirm this diagnosis. Usually it is wear in the bearings that allows the shaft to rock and destroy the turbo seals. While this is not a common problem, it is possible for a head gasket to split by an oil passage and allow oil into the combustion chamber. Check the spark plugs; if one

The combustion chamber can produce smoke with confusing different colors. Blue smoke typically indicates oil burning. White smoke typically indicates burning coolant (steam). Black smoke indicates a rich fuel mixture.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-12  Replacing valve seals with the head installed.

is drenched in oil, literally dripping, one of the possible causes is a blown head gasket. Perform a compression test. If the readings are normal or just slightly low, they point to a head gasket. If the rings were badly worn, you would usually get low compression results. Look very closely at the head gasket once the head is off to be sure that the head gasket is the cause of the blue smoke. You should be able to see a crack or path in the gasket from an oil passage into the combustion chamber. SERVICE TIP  Many manufacturers are having problems with head gasket sealing. Sometimes replacing the gasket is performing a complete repair.

Worn rings are a common cause of oil consumption. The engine may smoke all the time, but it will usually emit more blue smoke while accelerating. Perform a cylinder leakage test to confirm your suspicions. When the rings are badly worn, you will need to rebuild or replace the engine. Fully evaluate the condition of the engine, including valve seating, oil pressure, noises, cylinder leakage, and oil consumption. This will help you determine whether it would be more cost-effective to rebuild an engine or to replace it with a rebuilt unit. If the engine has valve problems, knocking noises, and excessive cylinder leakage, for example, it will likely be more efficient and inexpensive to replace the engine. In other cases, you may conclude that a set of rings and engine bearings will cure the problems and repairing the engine will be the best option.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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White Smoke When clouds of white smoke are pouring out of the tailpipe, it usually indicates that the head gasket is blown; otherwise, there is a significant crack in the block or head. The leak is most commonly past the head gasket, but a crack in the cylinder head or block will also cause coolant consumption. A distinct puff or small cloud of white smoke at startup, coupled with rough running, may be the result of a small crack in the head gasket or the cylinder head. A faulty head gasket or a cracked cylinder head or block can cause a number of different symptoms. The most obvious sign of one of these problems is excessive white, sweet-smelling smoke coming from the tailpipe. Other times the symptoms may include erratic heat and engine temperature; consistent or intermittent overheating; rough running; misfiring, especially at start-up; excessive pressure with bubbles in the cooling system; coolant overflow; coolant loss without an external leak; low compression on two adjacent cylinders; and coolant mixed in the oil, creating a fluid in the lubrication system that closely resembles a coffee milkshake (its lubricating quality is about as effective as a coffee milkshake, too). Prompt repair of a vehicle exhibiting any of these symptoms is essential to prevent more severe engine damage. Overheating typically causes failures of the head gasket, head, or block. Do not simply replace the faulty part. Thoroughly evaluate the cooling system to find the cause of overheating before calling the job complete. These failures will very often cause the telltale symptom of white smoke blowing out of the tailpipe as coolant leaks into the combustion chamber and burns. SERVICE TIP  Check the manufacturers’ service information, including technical service bulletins (TSBs). TSBs are bulletins that the manufacturer publishes when it has a common problem with its vehicles and has identified an effective correction. Some manufacturers are recommending that a liquid “stop leak” chemical be added to the coolant to try to seal the head gasket rather than replacing the gasket. Use only the chemical recommended by the manufacturer.

Occasionally, the crack in the head gasket, head, or block is very small and will cause less-dramatic symptoms. When the engine is cool, the metals in either of the suspect parts contract and enlarge the crack. Coolant may leak into the affected cylinder and foul the spark plug or cause small amounts of white smoke to exit the tailpipe. Symptoms may occur for a short time after start-up; then the engine heat can cause enough expansion in the metal to seal the gap. To confirm your diagnosis, remove the spark plugs, allow the engine to cool thoroughly, and place rated system pressure on the coolant using a pressure tester (Figure 5-13). Let the vehicle sit for as long as is practically possible, but at least one half hour. Disable the fuel system; then have an assistant crank the engine over and watch closely for coolant spray out of a cylinder. Sometimes it is helpful to place a paper towel in front of each plug hole so you can check each cylinder. Any coolant from a cylinder indicates a sealing failure. If you are uncertain of the result from a cylinder, perform a cylinder leakage test to confirm your suspicion. Combustion gases leaking into the cooling system may cause erratic temperatures, overheating issues, and problems of excess pressure and boiling over. The gases can form air pockets in the engine, preventing the thermostat from operating properly. When the leak is larger, the gases produce enough pressure in the system to force the cap to relieve pressure and coolant with it. One way to check for the presence of exhaust gases in the cooling system is to install a pressure tester on the filler neck. Do not pump any pressure

Caution If the engine does not crank over at all or at a normal rate of speed, stop your testing because the engine could be hydrolocked. This means that a cylinder(s) is so full of coolant that the engine cannot displace the coolant; nor can it compress it. Putting a battery charger on the system and continuing to crank could crack a piston, cylinder head, or even the block. Removing all the spark plugs will minimize the risk of this during testing.

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Figure 5-13  Pressurize the cooling system, and then check for leaks into the combustion chambers.

A chemical combustion tester uses a chemical that reacts to combustion gases. When air is passed across the solution from on top of the radiator, no combustion gases should be present. If they are, a problem with the head or head gasket is indicated.

on the tester. If compression pressure is leaking into the coolant, the pressure on the tester gauge will rise rapidly. Sometimes the leak is large enough to diagnose by observation. Be certain that the engine is cool enough to run without the pressure cap on for a few minutes. Remove the cap, and start the engine. If engine coolant bubbles violently and sprays out the top of the filler, then the head gasket, or head or block, has failed. When the problem is not this severe, use a chemical combustion tester to confirm your suspicions of leakage (Figure 5-14). This tester uses a chemical solution that changes color when exposed to combustion gases. Remove the pressure cap, and start the engine. Place the tester on the top of the reservoir or radiator. Use the bulb to pull air (not coolant) from the top of the fluid. Pump the bulb several times with the engine running, and watch the color of the liquid in the chamber. If it changes color, usually from blue to yellow, you have diagnosed a head gasket, head, or block leak. On an older vehicle with an automatic transmission, it is possible that a leaky vacuum modulator could cause these symptoms. On transmissions with a vacuum modulator, it is possible for the diaphragm inside to rip. This allows the vacuum line attached from the intake manifold to the modulator to pull in high quantities of automatic transmission fluid (ATF). The ATF introduced into the intake manifold is then burned in the cylinders and can also cause excessive white smoke from the tailpipe. A simple test to eliminate the modulator as the problem is to remove the vacuum line from the modulator and check to be sure no ATF is present in the line. If the modulator is faulty, the smoking will stop with the vacuum line disconnected. When coolant has gotten into the combustion chamber, you must also check the condition of the oil. Coolant that mixes with the oil produces a liquid very similar to a coffee milkshake. Its lubricating qualities are less effective than a good frappé. The very thick mixture of oil and coolant will block oil passages and quickly destroy the engine bearings. If the oil has been contaminated with coolant, warn the customer that major bottom-end damage may have occurred (Figure 5-15). If the engine has been run for any length of time with this “lubrication,” you will likely hear knocking from the bottom end of the engine. When the engine has high mileage, it may be advisable to check the price and availability of a rebuilt engine to repair the extensive engine damage this problem can cause.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Figure 5-14  Pull gases from above the coolant through the chemical in the combustion tester.

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Figure 5-15  This coolant-contaminated oil wrecked havoc in this engine.

Black Smoke An engine running too rich causes black smoke. Eliminate engine breathing problems first. Check the air filter and the exhaust system for restrictions. You may also need to check the fuel delivery system for faults. Possible problems include a faulty mass airflow (MAF) sensor or fuel pressure regulator, a leaking or stuck-open injector(s), an inaccurate engine coolant temperature sensor or oxygen sensor (O2S) (Figure 5-16), or faulty engine control wiring. You can use a scan tool to help verify proper operation of the sensors. Follow

Pre-catalyst oxygen sensor for air fuel mixture control

A fuel pressure regulator is typically a mechanical device that maintains the correct fuel pressure in the fuel rail the injectors sit in. An oxygen sensor sits in the exhaust stream and measures the amount of oxygen present in the exhaust. One use of this sensor is to help the computer to determine whether the engine is running rich or lean.

Post-catalyst oxygen sensor for testing converter efficiency

Figure 5-16  This engine uses an oxygen sensor before the catalytic converter to adjust the air-fuel ratio and another one after the converter to evaluate the converter’s efficiency. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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the manufacturer’s diagnostic troubleshooting chart to locate the cause of the problem. A cylinder(s) with low compression can cause less air to be pulled into the cylinder and for the air-fuel mixture to be less combustible. This can result in imperfect combustion and the emission of black smoke from the tailpipe. Check compression to verify that the engine is mechanically sound. The catalytic converter suffers from rich running and could become partially restricted or plugged. It could also trigger the MIL and set a DTC for low-catalyst efficiency on OBD II vehicles.

Oil Consumption Diagnosis Oil consumption can vary from engine to engine greatly. Oil consumption is defined as oil burning in the combustion chamber. Remember that some oil will normally burn in the combustion chamber due to the design and tolerances of the piston and rings. Some manufacturers use higher-quality piston rings and allow for less tolerance and clearance in the combustion chamber, while others do not. Oil consumption is considered excessive when it affects the customer’s ability to drive the car normally in-between oil changes or when it surpasses the manufacturers’ expectations. Oil consumption has many variables that can be controlled. Most manufacturers will provide a technical service bulletin that describes how to evaluate if a vehicle is consuming oil excessively or not. Some vehicle manufacturers claim that 1 quart or more consumed in 1,000 miles or less is excessive, while others claim it is normal for a highmileage engine. Some of the following items are conditions that may help a technician indicate when it is excessive oil consumption: ■■ Improper SAE oil viscosity for the temperature range used ■■ Improperly read oil level indicator ■■ Check the oil while the car is standing on a level surface. ■■ Allow adequate drain-back time. ■■ Continuous high-speed driving ■■ Broken, improperly installed, worn, or unseated piston rings ■■ Piston improperly installed or improperly fitted ■■ Heavy trailer towing (overloading) and excessive engine acceleration ■■ Continuous driving in the incorrect transmission range ■■ Malfunctioning PCV (positive crankcase ventilation) system ■■ Worn valve stem seals and/or valve guides ■■ Plugged cylinder head gasket oil drain holes

IMPROPER COMBUSTION

Preignition means that a flame starts in the combustion chamber before the spark plug ignition. Detonation is a ­dangerous explosion that occurs when two flame fronts collide in the combustion chamber.

Improper combustion can cause serious engine problems if it is left unrepaired. It can also be the cause of serious engine damage, and it will be absolutely critical that you recognize the problem during your engine overhaul. Preignition can cause a loss of power, but left uncontrolled it can lead to more damaging engine detonation. Detonation causes piston and ring damage, bent connecting rods and worn bearings, top ring groove wear, blown head gaskets, and possibly complete engine failure. Misfire will cause power loss, contamination of the engine oil, and catalytic converter failure. Common causes of preignition and detonation are: ■■ Deposits in the cooling system around the combustion chamber ■■ Engine overheating ■■ Too hot a spark plug ■■ An edge of metal or gasket hanging into the combustion chamber ■■ Fuel with too low an octane rating

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

A faulty exhaust gas recirculation (EGR) system Improper ignition timing ■■ Lean air-fuel mixtures (when there is less-than-desired fuel mixed with air) ■■ Carbon buildup in the combustion chamber ■■ A faulty knock sensor (KS) ■■ Excessive boost pressure from a turbocharger or supercharger Each of these areas should be investigated when a concern of preignition or detonation exists. ■■ ■■

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A knock sensor (KS) is bolted into the engine and senses engine vibrations that resemble knock. It relays this information to the PCM so it can adjust ignition timing to try to reduce knocking.

CUSTOMER CARE  Communication with the customer is essential to excellent repair work. In the case of engine preignition or detonation, it is very important to discuss any recent changes in driving habits or repair work with the customer. Did the customer recently change fuel brand or octane level? Did he just have his spark plugs changed? Several questions may lead you to a simple answer to a problem that is sometimes difficult to diagnose.

Check the engine for DTCs. Often the PCM will offer a hint about a problem. If the EGR system is not functioning, for example, combustion will be too hot and could easily lead to detonation. Evaluate the cooling system to be sure it is operating properly (Figure 5-17). If the engine is turbocharged or supercharged, verify that boost pressures are being controlled properly. Verify that the proper spark plugs are installed in the engine. An air-fuel mixture that is too rich or too lean, a faulty ignition system component, a faulty fuel injector, or inadequate cylinder compression can cause engine misfire. Most OBD II vehicles will identify an engine misfire and illuminate the MIL and set a DTC (Figure 5-18). Use a scan tool to identify the cylinder(s) whenever possible. You may also use a power balance test or a compression test to identify the faulty cylinder(s). Mechanical failures such as weak compression, burned valves, engine vacuum leaks, worn lifters, or rocker arms can all cause an engine misfire.

Figure 5-17  You can monitor areas of the engine with an infrared pyrometer.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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MIL light

Figure 5-18  The malfunction indicator light (MIL) will come on when the PCM has detected a problem that could allow emissions to increase; this certainly includes misfire.

COMPRESSION TESTING A cranking compression test measures the compression pressure in a cylinder while the engine is cranking. A running test checks compression with the engine running.

A compression test is an excellent way to determine if an engine has serious mechanical problems. When an engine is running poorly, it is important to establish that the mechanical function of the engine is sound before delving into testing the myriad of systems and components that could also cause drivability issues. Many technicians will perform a compression test on an engine that is running quite poorly before performing a major maintenance service. It is important to perform a compression test before undertaking any major engine work. You should know whether you will be performing work on the cylinder head and valves only or if the entire engine needs to be overhauled or replaced. A valve job, replacing or machining the valves and seats to reestablish proper sealing, may cost upward of $1,000 on many engines. A complete engine overhaul of the head and block or installing a crate engine is likely to set the customer back at least twice that amount. Compression testing can help provide you and the customer with information to make an appropriate repair choice.

Cranking Compression Test A cranking compression test is the most commonly used type of compression testing. It can clearly determine if the valves, rings, and head gasket(s) are sealing the combustion chamber properly (Figure 5-19). When any of those components are faulty, the engine may not be able to develop adequate compression. The manufacturer will provide a specification for the appropriate cranking compression pressure. Low compression will cause less productive combustion. You and the customer will notice that the engine lacks power or misfires on a cylinder(s). To perform a cranking compression test (Photo Sequence 11): 1. Let the engine warm up to normal operating temperature. (This ensures that the pistons have expanded to properly fit and seal the cylinder.) 2. Let the engine cool for 10 minutes so you don’t strip any threads; then remove the spark plugs. Remember to keep them in order so you can read them. 3. Block the throttle open at least part way open so the engine can breathe. 4. Disable the fuel system by removing the fuel pump fuse or relay to prevent contamination of the engine oil. 5. Disable the ignition system so you do not damage the coils. You can either remove the ignition fuse or remove the low-voltage connector to the coil(s). Do not simply remove the plug or coil wires and let them dangle. The coil can be damaged as it puts out maximum voltage trying to find a ground path for the wires. 6. Install a remote starter or have an assistant help you. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Spark plug gasket or seat

Exhaust valve

Intake valve

Piston rings

Head gasket

Figure 5-19  A cranking compression test will detect leaks at the valves, rings, pistons, and head gasket.

Figure 5-20  This style compression tester has adaptors that thread into the spark plug hole.

7. Carefully thread the compression tester hose into the spark plug hole and attach the pressure gauge to the adaptor hose (Figure 5-20). 8. Crank the engine over through five full compression cycles. Each cycle will produce a puffing sound as engine compression escapes through the spark plug ports. 9. Record the first puff and the final pressure. 10. Repeat the test on each of the other cylinders.

Analyzing the Results With all the pressure readings in front of you, compare them to the manufacturer’s ­specifications. Typical compression pressures on a gas engine range between 125 psi and 200 psi. The readings should be close to the specification and within 15 to 20 percent of each other. Some manufacturers specify only that the compression be over 100 psi and that each reading is within 20 percent of the others. To calculate 20 percent easily, take the normal reading (say, 160 psi) and drop the last digit (16 psi). Multiply by 2 (32 psi), and that is 20 percent. If the readings were 160, 150, 100, and 155, the third cylinder is more than 32 psi different than the other three. That indicates a significant problem with cylinder number three that must be identified and corrected. SERVICE TIP  A “blown” head gasket that is allowing coolant into the combustion chamber may be doing an adequate job of sealing compression. If an engine passes a compression test, it does not prove that the head gasket is sealing properly.

If one or more cylinders are below specification, it is likely caused by worn rings, burned valves, or valves sticking open from carbon on the seats, a faulty head gasket, or a worn or broken piston. Perform a wet compression test to help find the probable cause. When all the cylinders are slightly low, it usually indicates a high mileage engine with worn rings. Two adjacent cylinders with low compression readings may indicate a blown head gasket leaking compression between two cylinders. If all the cylinders are near zero or very low, suspect improper valve timing. A timing belt, chain, or gears that have “jumped” time by slipping a tooth will allow the valves to be open at the wrong time, causing low compression readings. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 11

Typical Procedure for Performing a Cranking Compression Test

P11-1  Tools required to perform this task: compression tester and adapters, spark plug socket, ratchet, extensions, universal joint, remote starter button, battery charger, service manual, and squirt can of oil.

P11-2  Follow the service manual procedures for disabling the ignition and fuel systems.

P11-3  Clean around the spark plugs with a low-pressure air gun, and remove all of the spark plugs from the engine.

P11-4  Install the remote starter button.

P11-5  Carefully install the compression tester adapter into the first cylinder’s spark plug hole.

P11-6  Connect the battery charger across the battery, and adjust to maintain 13 to 14.5 volts. This is needed to allow the engine to crank at constant speeds throughout the test.

P11-7  With the throttle plate held or locked into the wide-open throttle position, crank the engine while observing the compression reading.

P11-8  Continue to rotate the engine through four compression strokes as indicated by the jumps of the needle.

P11-9  Record the reading after the fourth compression stroke. Continue until all cylinders have been tested, and compare the test results. Compare test results with the manufacturer’s specifications.

WET COMPRESSION TEST To help determine the cause of a weak cylinder, perform a wet compression test (Figure 5-21). Use an oil can and put two squirts of oil into the weak cylinder. Reinstall the compression gauge, crank the engine over five times, and record the reading. If the low reading cylinder increases to almost normal compression pressure, it is likely worn Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Figure 5-21  Hold this compression gauge firmly against the spark plug hole to measure compression.

Figure 5-22  This cylinder showed low compression of only 100 psi while cranking dry and wet. A leak-down test will verify a leaking valve.

rings that are causing the cylinder leakage. The extra oil in the cylinder helps the rings to seal better during the test. If a valve is burned or being held open by carbon or if there is a hole in the piston, a film of oil will not dramatically improve the compression pressure. Note that a wet compression test may not be as effective on horizontally opposed engines, because the oil will seal only the lower half of the cylinder wall. Look at the examples that follow: Compression test results Cyl. No. 1

Cyl. No. 2

Cyl. No. 3

Cyl. No. 4

Cyl. No. 5

Cyl. No. 6

175 psi

165 psi

170 psi

80 psi

170 psi

170 psi

Wet compression test Cyl. No. 4 160 psi

This is a clear indication that the rings are severely worn on cylinder number four. If the wet compression test had shown no change or a slight rise, for instance, only 105 psi, you would suspect a burned valve or leaking valve. To definitively determine the cause of low cranking compression, perform a cylinder leakage test (Figure 5-22).

RUNNING COMPRESSION TEST It is possible that the cranking compression can show good results but the engine still is not mechanically sound. A cranking compression test does not do a good job of testing the valvetrain action. There is so much time for the cylinder to fill with air when the engine is spinning only at cranking speeds of about 150–250 rpm. A more accurate way to test the loaded operation of the valvetrain is to perform a running Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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compression test. Running compression readings will be quite low compared to the cranking ­compression pressures because there is so much less time to fill the cylinders with air. If you have identified a weak cylinder through power balance testing, check that cylinder and a few others to gain comparative information. In most cases, it is worth the time to check all the cylinders. To perform the running compression test: 1. Remove the spark plug only from the test cylinder. 2. Disable the spark to that cylinder by grounding the plug wire or removing the ­primary wiring connector to the individual coil. 3. Disable the fuel to the test cylinder by disconnecting the fuel injector connector. 4. Install the compression gauge into the spark plug port. 5. Start the engine and let it idle. 6. Release the pressure from the gauge that reading reflects cranking compression. Record the new pressure that develops at idle. 7. Rev the engine to 2,500 rpm. Release the idle pressure, and record the new pressure that develops at 2,500 rpm. 8. Remove the gauge and reinstall the spark plug. Remember to reattach the plug wire or coil and the fuel injector connector. 9. Repeat for several or all cylinders.

Analyzing the Results Generally, the running compression will be between 60 psi and 90 psi at idle and 30–60 psi at 2,500 rpm (Figure 5-23). The most important indication of problems, ­however, is how the readings compare to each other. Look at the following readings: Cyl. No. 1

Cyl. No. 2

Cyl. No. 3

Cyl. No. 4

Idle

70 psi

75 psi

45 psi

70 psi

2,500 rpm

40 psi

40 psi

20 psi

45 psi

Cylinder number three is barely below the general specifications, but it is clearly weaker than the other cylinders. These results warrant investigation of the ­problem in ­cylinder number three. The most likely causes of low running compression readings are: ■■ Worn camshaft lobes ■■ Faulty valve lifters ■■ Excessive carbon buildup on the back of intake valves (restricting airflow) (Figure 5-24) ■■ Broken valve springs ■■ Worn valve guides ■■ Bent pushrods SERVICE TIP  Direct injection engines tend to develop carbon deposits on intake valves.

Use a stethoscope, vacuum testing, and visual inspection under the valve covers to help locate the reason for the low reading. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

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Carbon buildup

Figure 5-23  The same cylinder showed low running compression at idle.

Figure 5-24 Excessive carbon buildup on the back of intake valves caused by a bad valve seal or guide leakage prevents the engine from pulling in enough air to make adequate power. The added weight can also cause the valve to float at higher rpms.

SERVICE TIP  If the piston and connecting rod are not exactly at top dead center (TDC), the engine may actually rotate as you apply air pressure. Inline engines need to be almost exactly at TDC, while V-type engines can be a little off. If the engine starts to turn while you apply air pressure, try to move the cylinder closer to TDC. If you still cannot get the cylinder to stop moving, then try other things like holding the ratchet (watch your hand), using a piston position locater or checking the timing marks on the crankshaft pulley. Each vehicle is very different, but you may be able to use a bar in a location where it stops a pulley from moving.

CYLINDER LEAKAGE TESTING Once you have identified a cylinder(s) with low cranking compression, you can use a ­cylinder leakage test to pinpoint the cause of the problem. To perform a cylinder leakage test, you put pressurized air in the weak cylinder through the spark plug hole when the valves are closed. You can then listen for leakage of air from the combustion chamber at various engine ports to determine the source of the leak. This is an excellent way to gather more information before disassembling the engine or when deciding whether a replacement engine should be installed. A cylinder leakage test is also a very thorough way of evaluating an engine when someone is considering purchasing a vehicle. You can even perform a cylinder leakage test on a junkyard engine to assess its value before purchasing it.

A cylinder leakage test places air pressure into a combustion chamber so you can listen for leaks from possible faulty components.

CUSTOMER CARE  A customer was anxious to buy a good-looking, performancemodified Honda. He was finally convinced to allow us to perform a cylinder leakage test after we noticed a bit of blue smoke coming from the tailpipe. A leak-down test showed very serious ring wear on two cylinders. While he still bought the car, he paid $1,500 less for it than he had planned. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-25  A cylinder leakage tester is used to ­indicate how well a cylinder is sealed.

Cylinder Leakage Test A cylinder leakage tester (Figure 5-25) applies compressed air to a cylinder through the spark plug hole. Before the air is applied to the cylinder, the piston of that cylinder must be at TDC on its compression stroke. A threaded adapter on the end of the air pressure hose screws into the spark plug hole. The source of the compressed air is normally the shop’s compressed air system. A pressure regulator in the tester controls the pressure applied to the cylinder. An analog gauge registers the percentage of air pressure lost from the cylinder when the compressed air is applied. The scale on the dial face reads 0 to 100 percent. A zero reading means that there is no leakage from the cylinder. Readings of 100 ­percent would indicate that the cylinder will not hold any pressure. Most vehicles, even new cars, experience some leakage around the rings. Up to 20 percent is considered acceptable during the leakage test. When the engine is actually running, the rings will seal much better, and the actual percentage of leakage will be lower; however, there should be no leakage around the valves or the head gasket. Possible causes of excessive leakage can be from valves, piston rings, and head gasket. The location of the compression leak can be found by listening and feeling for air leaks around various parts of the engine. Bubbles found in the cooling system indicates a problem with a blown head gasket or a cracked head, or cylinder wall. The cylinder leakage test can help you evaluate the severity of an engine mechanical problem and pinpoint the cause. You can test one low cylinder to find a problem, or you can test each cylinder to gauge the condition of the engine. Like a compression test, the cylinder leakage test will detect leaks in the combustion chamber from the valves, rings, or pistons and the head gasket. From this test, however, you can clearly identify which is the cause of the leak. To perform a cylinder leakage test: 1. Let the engine warm up to normal operating temperature. 2. Let the engine cool for 10 minutes, and then remove the spark plug from the cylinder to be tested. 3. Remove the radiator cap and the PCV valve. This prevents damage to the ­radiator or engine seals if excessive pressure leaks into the radiator or the engine’s crankcase. 4. Turn the engine over by hand until the cylinder is at TDC on the compression stroke. This ensures that the valves will be closed and the rings will be at their Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

highest point of travel. The cylinders wear the most at the top because of the heat and pressure of combustion, so if the rings are leaking, they will show the greatest evidence at the top. There are a few different methods of getting a cylinder to TDC compression, depending on the engine. a. Have an assistant turn the engine over slowly while watching the piston come up to TDC. You should be able to feel and hear blowing out of the spark plug hole if it is coming up on the compression stroke. If you begin the leakage, test and show 100 percent leakage, you are on TDC exhaust. Rotate the engine 360 degrees and retest. b. Remove the valve cover, and watch the rockers or camshaft as you turn the engine over. On the intake stroke, the intake valve will open and then close. Then both the valves will remain closed while the piston comes up to TDC. If the engine has rocker arms, move them up and down to be sure they both have lash (clearance) between the arm and the pushrod. If the engine has an overhead camshaft(s), the followers will be on the base circle not the lobes of the camshaft. c. If the vehicle has a distributor, remove the cap and rotate the engine until the rotor points at the test cylinder’s firing point. SERVICE TIP  A TDC “whistle” can be used to easily locate TDC on a cylinder.

5. With the cylinder at TDC compression, thread the cylinder leakage tester adaptor hose into the spark plug hole. 6. Apply air pressure to the leakage tester, and calibrate it according to the equipment instructions. On the tester shown, you turn the adjusting knob until the gauge reads 0 percent leakage without it attached to the cylinder. 7. Connect the leakage tester to the adaptor hose in the cylinder while watching the crankshaft pulley. If the engine rotates at all, reset it to TDC. When the engine is right at TDC, it will not rotate with air pressure applied. 8. Read the percentage of leakage on the tester and gauge as follows: ■■ Up to 10 percent leakage is excellent; the engine is in fine condition. ■■ Up to 20 percent leakage is acceptable; the engine is showing some wear but should still provide reliable service. ■■ Up to 30 percent leakage is borderline; the engine has distinct wear but may ­perform reasonably well. ■■ Over 30 percent leakage shows a significant concern that warrants repair. 9. With the air pressure still applied, use a stethoscope and listen at the following ports: ■■ At the tailpipe: Leakage here indicates a burned or leaking exhaust valve. ■■ At the throttle or a vacuum port on the intake manifold: Leakage here indicates a burned or leaking intake valve. ■■ At the radiator or reservoir cap: Leakage here proves that the head gasket is leaking. ■■ At the oil fill cap or dipstick tube: Leakage here indicates worn rings. ■■ If the leakage at the oil fill is near 100 percent, suspect damage to a piston (Figure 5-26). 10. Release the pressure, remove the adaptor, and rotate the engine over to the next test cylinder. Repeat as indicated. Refer to Photo Sequence 12 for detailed pictures and directions on performing a cylinder leakage test. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 5-26  This destroyed piston showed 100 percent leakage.

SERVICE TIP  Direct injection engines tend to develop carbon deposits on intake valves.

SERVICE TIP  There will always be some leakage past the rings; a light noise is to be expected. Excessive ring wear will cause distinct blowing out of the cap or dipstick hole. You will be able to hear the noise and feel the pressure.

CUSTOMER CARE  While a cylinder leakage test can identify the primary cause of low compression readings, remember to keep your mind and eyes open to other problems when repairing the engine. Do not automatically inform a customer that an exhaust valve is leaking and a valve job will cure the problem. Consider the engine mileage, oil condition, pressure and usage, and degree of leakage past the rings. If the engine has high miles, it is very likely that the rings are significantly worn. By replacing the faulty valve(s) and restoring the others to like-new condition, you will increase the compression and combustion pressures. The change may be significant enough that the old rings will not seal as well as they had been before the valve job. In this case, the customer would be back complaining about blue smoke from oil consumption or about the engine still lacking adequate power. This may very well be an example of when a replacement engine would be the most cost-effective repair for the customer. Evaluate the whole situation, and make your recommendation to the customer. If you offer the customer repair options, be very clear about explaining the possible consequences. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

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PHOTO SEQUENCE 12

Typical Procedure for Performing a Cylinder Leakage Test

P12-1  Loosen the ignition cassette to access the spark plugs.

P12-2  Disconnect power to the ignition ­cassette to avoid damaging the coils.

P12-3  Remove the ignition cassette.

Rotate engine over slowly with crank pulley

P12-4  Remove the spark plugs.

P12-7  Connect adaptor to test cylinder and read leakage. This cylinder is leaking slightly over 30 percent.

P12-5  Rotate the engine to TDC on the test cylinder’s compression stroke for the leakage testing.

P12-6  Hook up shop pressure to the leakage tester, and set to 0 percent leakage.

P12-8  Listen for air at the intake manifold for leakage past an intake valve.

P12-9  Listen for air at the oil fill to detect leakage past the rings. In this case you could feel the air blowing out the fill pipe.

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PHOTO SEQUENCE 12 (CONTINUED)

P12-10  Listen for air in the coolant reservoir for indications of a leaking head-gasket.

P12-11  Listen for air at the tailpipe to find leakage past an exhaust valve.

P12-12  The moderate blue smoke from the tailpipe substantiates the diagnosis of worn rings on this high mileage vehicle.

Engine Vacuum Testing Measuring intake manifold vacuum is another way to diagnose the condition of an engine. Manifold vacuum is tested with a vacuum gauge (Figure 5-27). Vacuum is measured in inches of mercury (in. Hg), kilopascals (kPa), or millimeters of mercury (mm Hg). To measure vacuum, a flexible hose on the vacuum gauge is connected to a source of manifold vacuum, either on the intake manifold or on a point below the throttle plate. Sometimes this requires removing a plug from the manifold and installing a special fitting. The test is made with the engine cranking or running. A good running vacuum reading is typically at least 16 in. Hg. However, a reading of 15–20 in. Hg (50–65 kPa) is normally acceptable. Because the intake stroke of each cylinder occurs at a different time, the production of vacuum occurs in pulses. If the amount of vacuum produced by each cylinder is the same, the vacuum gauge will show a steady reading. If one or more cylinders are producing different amounts of vacuum, the gauge will show a fluctuating reading. Low or fluctuating readings can indicate many different problems; for example, a low, steady reading might be caused by incorrect valve timing, engine wear, restricted exhaust, or a vacuum leak (Figure 5-28). A fluctuating needle can be caused by a valve-related problem.

Figure 5-27  Vacuum Gauge. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Diagnosing Engine Performance Concerns 15

15 10

20

5

10

25

0

25

0

10

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30

Carburetor or injector adjustment

5

30 Burnt or leaking valves

0

30

10

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0

25

15 10

20

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25

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30 Leaking head gasket

15 20

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5

Weak valve springs

15 20

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Manifold leak

15

15

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30

0

Late ignition timing

0

10

20

5

30

10

15

30 Sticking valves

20

5

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30

0

Choked catalytic converter or muffler

Figure 5-28  Vacuum readings.

ENGINE NOISE DIAGNOSIS Irregular engine noises may be caused by major or minor engine problems. Your job is to diagnose the noise as accurately as possible to be able to repair the engine in the most effective and efficient way. Low oil pressure can cause or increase the level of engine noises, so check that the engine has adequate oil and pressure before drawing conclusions. In many cases, you should consider changing the oil before performing an engine noise diagnosis. This allows you to use the correct oil and filter. Some bottom-end noises clearly indicate an engine that requires a thorough overhaul or replacement. Other noises may be resolved by much less drastic measures. While it is difficult to describe noises on paper, a few guidelines should help you narrow down the possible problem(s). A deep knock within the engine will require engine disassembly or replacement. If you disassemble the engine, be sure to look for all potential problems. Noise diagnosis should help you identify problems but not limit your investigation once the engine is apart. It is important to remember the engine’s operation, how the various engine components are manufactured, and how much each one might weigh. These items may help clue you into what component is making noise and what has to be done to repair it. For example, connecting rods and the crankshaft all rotate at the same speed and are located in the lower part of the engine. Valvetrain components rotate half as fast, weigh less, and are located in the upper part of the engine. Valvetrain components will also have a different frequency because they rotate at half the speed of the crankshaft. This is important because as the engine speed increases, the difference in frequency will be greater. Body and exhaust components can also create noises that will echo under the hood and seem like an engine noise. Make sure to check these and eliminate them before going too far.

Bottom-End Knock A loud knocking noise from the bottom end of the engine, a bottom-end knock portends imminent failure of the engine. This is a deep knocking sound caused by excessive clearance between the main or rod bearings and the crankshaft (Figure 5-29). Place a

Special Tools Stethoscope

A bottom-end knock is a loud, deep knocking noise heard from the lower end of the engine. It is usually an indication of serious engine problems, such as worn main or rod bearings or crankshaft, or low oil pressure.

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Figure 5-29  These rod journals were destroyed when a bearing spun; the knocking sounded as serious as the fault.

The bell housing is the portion of the transmission that bolts to the back of the engine.

stethoscope on the block just above the oil pan, and listen while the engine idles and when you open the throttle. A loud rapping noise indicates excessive bearing wear. Check the oil pressure at idle; low readings confirm your diagnosis. Excess bearing clearances allow oil to leak through the bearings, lowering pressures and allowing the crankshaft journals to crash against the bearing face without a soft cushion of oil. Engine knocking that is repaired promptly may require only engine bearing and ring replacement. If the engine is allowed to run for extended periods of time with worn bearings, the crankshaft and connecting rods will likely be damaged. This will often warrant a replacement engine rather than an overhaul. Be certain that the flexplate or flywheel is not cracked or loose and that the catalytic converter is not rattling; these problems can cause knocking that sounds very much like a bearing knock. Use your stethoscope on the bell housing and on the catalytic converter to clearly identify the source of the noise.

Crankshaft End Play A small amount of excessive crankshaft end play is required. Excessive end play is caused by bearing wear and can cause serious engine damage. A thrust bearing is a bearing on the crankshaft that is used to control the amount of wear when the crankshaft moves back and forth.

Valvetrain clatter is a light tapping noise from the top of the engine, associated with valverelated components.

When an engine knocks or clunks loudly on acceleration, suspect excessive crankshaft end play. The repair requires replacement of the engine main bearings, but while you are disassembling the engine, you must pay particular attention to the crankshaft and block. If the crankshaft has been slamming against the block without the benefit of a cushion from the thrust bearing, significant damage may have occurred. The thrust bearing is designed to minimize forward and backward movement of the crankshaft to protect the crankshaft and block from wear, but look for scoring along the thrust surfaces of the block and crankshaft (Figure 5-30). Minor damage can be corrected by a different thrust bearing, but serious damage requires component replacement. If left unrepaired, excessive crankshaft end play can result in the crankshaft breaking through the block. Many other drivetrain problems can cause clunking on acceleration. Make sure that the noise is coming from the engine rather than the differential or a U-joint, for example. You can often feel excessive crankshaft end play with the engine installed. Put the engine on a lift, and pry and push the crankshaft pulley forward and backward in the engine block. Movement and noise should be minimal. If the crankshaft moves significantly (more than a few thousandths of an inch), and you can hear a knocking noise, the engine will require repairs.

Piston Pin Knock When a piston pin develops clearance within the piston pin bore, you will hear a higher pitch, double-time knock at the top of the block. The noise is deeper than valvetrain clatter but not as deep as bottom-end knocking. Place a stethoscope near the top of the

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Figure 5-30  This thrust bearing was worn down to the copper causing a clunking on acceleration. It did its job of protecting the crank and block; a new set of bearings cured the problem.

257

Figure 5-31  The piston let loose due to excessive pin wear. It caused extensive cylinder and head damage.

block and listen for two knocks close together. The pin will knock as the rod pushes the piston up and then again as combustion forces the piston down. It is important to repair this problem immediately. Excessive pin clearance will often break the piston off the rod (Figure 5-31). This can cause extensive damage to the block and cylinder head.

Piston Slap Piston slap occurs when there is too much clearance between the piston and the cylinder. It usually begins as a knocking noise when the engine is cold and goes away as the engine fully warms up. Prompt repair can prevent piston breakage and more serious engine damage. Once the piston is slapping continuously, the engine is at risk of a catastrophic failure, even when the engine is warm. If you rebuild the engine, carefully measure the cylinder bore diameter, out-of-round, and taper. Often the repair for piston slap includes boring the cylinders out oversize and installing new pistons. In many cases, these extensive repairs will cost more than a crate engine, so a rebuilt engine assembly will be installed. Some manufacturers have been having problems with excessive piston slap on very low mileage engines. These engines are being replaced under warranty.

Timing Chain Noise A loose timing chain or worn gears will make a clacking or rattling noise, particularly when you allow the engine to decelerate after giving it some throttle. A chain will often slap on the timing chain cover when it wears. You will learn to identify this noise, but you can also verify it with a stethoscope on the timing cover. If the engine has gears, the noise will be less of a rattle and more of a knock. It will still be the worst during engine start-up and deceleration.

Piston slap is the knocking noise heard, especially when the engine is cold, on engines with cylinder wall wear.

Generally the deeper the engine noise or knocking is, the more extensive and expensive the repairs will be. Light ticking from the valvetrain may be relatively simple and inexpensive to repair. A bottom-end knock usually requires serious engine repairs or replacement.

Valvetrain Clatter When there is excessive clearance between components in the valvetrain, you will hear a tinny, clattering sound from the top of the engine. A common cause of valvetrain clatter is a collapsed hydraulic lifter. You may hear this in the morning, after a car has been sitting for an extended period, or after an oil change. The noise should go away within a few seconds. If the noise persists, the lifters are probably worn. Be sure that the engine is properly filled with clean oil before dismantling the engine to replace the lifters. Metallic clicking noises can also be caused by valves out of adjustment (too loose), a worn camshaft, worn lifters, or worn or broken rocker arms or rocker arm shafts. Remove the valve cover(s) to inspect the valvetrain components and look closely for signs of wear (Figure 5-32). Again, a stethoscope can help point you to the right area of the cylinder head or even to the affected cylinder.

Always check for TSBs when diagnosing engine noises.

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Figure 5-32  This badly worn lifter was causing serious valve-train clatter. The other lifters were not much better.

CASE STUDY A vehicle that was running very poorly with low power had been to two shops that tried unsuccessfully to locate the cause of the problem. A full maintenance service had been performed, as well as a new PCM, ECT, MAF, and turbocharger installed, to no avail! A cranking compression test showed adequate compression on each cylinder. After double-checking some of the previous work, the young technician at the new shop decided to perform a running compression test. The test showed very low readings on two cylinders. Careful inspection of the overhead camshaft showed well-worn lobes preventing adequate airflow into the engine. A new camshaft made the vehicle perform beautifully and made the frustrated customer very happy.

ASE-STYLE REVIEW QUESTIONS 1. A spark plug gap that is too wide can cause: A. Detonation B. Low compression C. Valvetrain clatter D. Misfire 2. Technician A says that black flaky carbon on a spark plug is caused by detonation. Technician B says that heavy tan deposits are caused by oil consumption. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. Technician A says that some platinum spark plugs may last up to 100,000 miles. Technician B says that it is reasonable to replace them at 60,000 miles. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. One weak cylinder is found during a power ­balance test. Technician A says it could be caused by a plugged fuel filter. Technician B says it could be caused by a bad fuel injector. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. Technician A says to check compression before disassembling an engine. Technician B recommends performing a ­compression test before completing a major maintenance service if the engine is running very badly. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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Diagnosing Engine Performance Concerns

6. Technician A says that cranking compression pressures are usually between 200 psi and 250 psi. Technician B says running compression pressures are lower than cranking compression pressures. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. A compression test is performed on an engine that is misfiring. All the pressures are between 175 psi and 185 psi except cylinder number five; it is 80 psi. Technician A says a valve seal could be bad. Technician B says the rings could be worn or broken. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. An engine produced the following compression pressures: cylinder number one, 150 psi; ­cylinder number two, 55 psi; cylinder number three, 45 psi; cylinder number four, 145 psi. Which is the most likely cause? A. A hole in the pistons B. A worn camshaft C. Bad rings D. A blown head gasket

259

9. An engine produces the following compression pressures: cylinder number one, 95 psi; cylinder number two, 140 psi; cylinder number three, 145 psi; cylinder number four, 135 psi. When a wet test is performed on cylinder ­number one, the pressure rises to 160 psi. The most likely cause of the problem with cylinder number one is: A. A blown head gasket B. Worn rings C. A bad oil pump D. A burned valve 10. An engine has 45 percent leakage, and air is heard at the intake manifold. Technician A says the rings are bad. Technician B says the engine should run fine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. An engine has low-running compression on two out of four cylinders; the cranking compression was normal. Technician A says the camshaft lobes may be worn. Technician B says the head gasket may be blown. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 2. A loud clattering is heard from the top of the engine. Technician A says it may be caused by ­collapsed lifters. Technician B says the rocker arms could be worn. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says that a loud clunk on acceleration may be caused by a loose timing chain. Technician B says that metallic clacking noise on deceleration is usually caused by worn camshaft bearings. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 4. A customer started up her car one extremely cold morning, and within a few minutes, a cloud of blue smoke was coming from the tailpipe. She stated that the engine had been running perfectly, with no smoking at all the day before. Which is the most likely cause? A. A blown head gasket B. Worn rings C. Bad main bearings D. Plugged PCV hose

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5. An engine with 135,000 miles is running poorly. The cause of low compression on the third cylinder is being diagnosed using a cylinder leakage test. The results show 55 percent leakage. Most of the leakage is past an intake valve, but there is ­significant air coming out the oil fill port. Technician A says that he would replace the bad valve.

Technician B says that he would recommend an engine overhaul or replacement. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

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Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

261

JOB SHEET

35

DIAGNOSING ENGINE NOISES AND VIBRATIONS Upon completion of this job sheet, you should be able to locate and recognize normal and abnormal engine noises and recommend repairs or further tests. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Performance: A.3. Diagnose abnormal engine noises or vibration concerns; determine necessary action. Tools and Materials • Stethoscope Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Check the oil level and correct as needed.

h

2. Start the engine and allow it to idle.

h

3. Are any abnormal noises coming from any areas of the engine?

h Yes  h No

4. Use an available information system to locate any technical service bulletins related to abnormal engine noises. Describe your findings: _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Use a stethoscope to listen to the bottom end of the block, the top end of the block, and the valvetrain. Describe your _______________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Raise the engine rpm to 2,500, and listen again for any unusual noises at the same locations. Describe your _______________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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7. Reduce the engine rpm to idle again, and listen at the accessories for unusual noises such as squealing bearings or rough metallic sounds. Describe your findings: _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Based on your tests and results, what are your recommendations? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

263

JOB SHEET

36

ANALYZING SPARK PLUGS AND PERFORMING A POWER BALANCE TEST Upon completion of this job sheet, you should be able to analyze spark plugs, perform a power balance test, and recommend repairs or further tests. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Performance: Ignition System Diagnosis and Repair, Task #4 Remove and replace spark plugs; inspect ­secondary ignition components for wear and damage. (P-1) A.6.

Perform cylinder power balance test; determine necessary action.

This job sheet addresses the following MLR task for Engine Performance: A.3.

Perform cylinder power balance test; determine necessary action.

Tools and Materials • Power balance tester • Insulated pliers • Scan tool Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Check the oil level and correct as needed.

h

2. Use an available information system to locate any technical service bulletins related to engine drivability concerns. Describe your findings: _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Start the engine and allow it to idle.

h

4. Record the engine idle speed. ___________________________________________________ Describe the idle conditions: ____________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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Task Completed 5. Prepare to perform a power balance test. If you are using an automated system, follow the instructions provided with the equipment. To perform a manual power balance test by disabling the spark to each cylinder in turn, follow these instructions: Using insulated pliers, remove the spark plug wire from cylinder number 1 and place the wire close to a good ground. Note the rpm drop and the idle condition. Describe your results: ________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Wait one minute between tests, so you do not overheat the catalytic converter. Repeat the power balance test on each of the other cylinders and describe your results: Cylinder number 2 ___________________________________________________________ _________________________________________________________________________ Cylinder number 3 ___________________________________________________________ _________________________________________________________________________ Cylinder number 4 ___________________________________________________________ _________________________________________________________________________ Cylinder number 5 ___________________________________________________________ _________________________________________________________________________ Cylinder number 6 ___________________________________________________________ _________________________________________________________________________ Cylinder number 7 ___________________________________________________________ _________________________________________________________________________ Cylinder number 8 ___________________________________________________________ _________________________________________________________________________ 7. Restore the engine to proper operating condition. Turn the engine off and allow it to cool before performing the spark plug analysis.

h

8. Analyze the results of the power balance test, and note any recommended repairs or tests. ______________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 9. Remove all spark plugs, and keep them in order so you can analyze the results of each plug. Describe your general results: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Describe the condition and written part number of each of the spark plugs: Cylinder number 1 __________________________________________________________ Cylinder number 2 __________________________________________________________ Cylinder number 3 __________________________________________________________ Cylinder number 4 __________________________________________________________ Cylinder number 5 __________________________________________________________ Cylinder number 6 __________________________________________________________ Cylinder number 7 __________________________________________________________ Cylinder number 8 __________________________________________________________ 10. Remove one spark plug wire at a time, and test the resistance, measure the length, and visually inspect each one. Good spark plug wires should have less than 5,000 ohms per foot. Cylinder

1

2

3

4

5

6

7

8

Resistance Length Good or Bad?

11. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

267

JOB SHEET

37

OIL AND COOLANT CONSUMPTION DIAGNOSIS Upon completion of this job sheet, you should be able to determine if the oil and coolant consumption on the vehicle you are working on is excessive. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Performance: A.4. Diagnose unusual exhaust color, odor, and sound; determine necessary action. This job sheet addresses the following AST/MAST task for Engine Repair: A.4. Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. This job sheet addresses the following MLR task for Engine Repair: A.3.  Inspect engine assembly for fuel, oil, coolant, and other leaks; determine necessary action. Tools and Materials • Coolant pressure tester • Service manual Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Turn the engine off, and let it sit for 5 minutes on a level surface. Check the oil and coolant levels. Describe your findings: _________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Use an available information system to locate any technical service bulletins related to oil and coolant consumption. Describe your findings: _________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Start the engine and allow it to idle.

h

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4. Check the exhaust tailpipe for blue, black, or white smoke. Describe your findings: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. What are the API and SAE ratings for the oil that should be used in this vehicle? ________________________________________________________________________ 6. According to the service manual, what driving conditions must the driver have to consider them classified under the severe maintenance service schedule? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 7. If the vehicle you are working on was classified in the severe service category, according to the service manual how often should the oil be changed? _________________________________________________________________________ 8. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

269

JOB SHEET

38

PERFORMING COMPRESSION TESTS Upon completion of this job sheet, you should be able to perform a cranking compression test and recommend repairs or further tests. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Performance: A.7. Perform cylinder cranking and running compression tests; determine necessary action. This job sheet addresses the following MLR task for Engine Performance: A.4. Perform cylinder cranking and running compression tests; determine necessary action. Tools and Materials • Compression tester • Oil can • Spark plug socket • Spark tester Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Check the oil level, and correct as needed.

h

2. Locate the compression specifications for the engine you are working on, and record them below: ________________________________________________________________ _________________________________________________________________________ 3. Start the engine, and allow it to idle until the engine is moderately warm. Allow it to cool slightly before removing the spark plugs.

h

4. Remove the spark plugs, and note their condition. Describe your results: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Prepare to perform a cylinder compression test. If you can, install a remote starter. Disable the fuel by locating the fuel pump fuse or relay and removing it. Disable the ignition system by removing the coil power wire or the ignition system fuse. Disable the fuel system by removing the fuse or relay for the fuel pump. Block open the throttle.

h

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Task Completed 6. Install the compression tester adaptor into the number 1 spark plug hole, and crank the engine over five times. Record your results: ____________________________________________________________ Repeat for each cylinder, and describe your results. Cylinder number 2 __________________________________________________________ Cylinder number 3 __________________________________________________________ Cylinder number 4 __________________________________________________________ Cylinder number 5 __________________________________________________________ Cylinder number 6 __________________________________________________________ Cylinder number 7 __________________________________________________________ Cylinder number 8 __________________________________________________________ 7. Analyze the results of the compression test, and note any recommended repairs or tests. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Identify the cylinder(s) with the lowest compression. Squirt 2 tablespoons of oil into the weak cylinder, and perform another compression test on that cylinder. Note the new results, and describe what problem this indicates: ____________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 9. Reconnect all the fuel and ignition components removed earlier, and start the engine. Let it run for a few minutes, and turn it off.

h

10. You may have to use the scan tool to clear and recorded codes when you are done.

h

11. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

271

JOB SHEET

39

PERFORMING A RUNNING COMPRESSION TEST Upon completion of this job sheet, you should be able to perform running compression tests and recommend repairs or further tests. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Performance: A.7. Perform cylinder cranking and running compression tests; determine necessary action. This job sheet addresses the following MLR task for Engine Performance: A.4. Perform cylinder cranking and running compression tests; determine necessary action. Tools and Materials • Compression tester • Spark plug socket • Spark tester • Scan tool Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Check the oil level and correct as needed.

h

2. Record the general running compression specifications at idle and at 2,500 rpm: _________________________________________________________________________ _________________________________________________________________________ 3. Start the engine, and allow it to idle until the engine is moderately warm. Allow it to cool slightly before removing a spark plug.

h

4. Remove a spark plug from cylinder number 1, and note its condition. Describe your results: __________________________________________________________ _________________________________________________________________________ 5. Install the compression tester adaptor into the number 1 spark plug hole, and run the engine. Release the pressure from the compression tester, and read the results at idle. Record your results: ____________________________________________________________ 6. Raise the engine speed to 2,500 rpm. Release the pressure from the compression tester, and record your results: ______________________________________________________ Repeat for each cylinder, and describe the spark plug condition and your idle and 2,500 rpm compression readings. Cylinder number 2 ________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Task Completed Cylinder number 3 ________________________________________________________ _________________________________________________________________________ Cylinder number 4 ________________________________________________________ _________________________________________________________________________ Cylinder number 5 ________________________________________________________ _________________________________________________________________________ Cylinder number 6 ________________________________________________________ _________________________________________________________________________ Cylinder number 7 ________________________________________________________ _________________________________________________________________________ Cylinder number 8 ________________________________________________________ _________________________________________________________________________ 7. Describe any significant differences between cylinders, and list the possible causes of low readings. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. You may have to use a scan tool to clear any diagnostic trouble codes present when testing is completed.

h

9. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Diagnosing Engine Performance Concerns

Name ______________________________________

Date __________________

273

JOB SHEET

40

PERFORMING A CYLINDER LEAKAGE TEST Upon completion of this job sheet, you should be able to perform a cylinder leakage test and recommend repairs or further tests. This job sheet addresses the following AST/MAST task for Engine Performance: A.8.

Perform cylinder leakage test; determine necessary action.

This job sheet addresses the following MLR task for Engine Performance: A.5.

Perform cylinder leakage test; determine necessary action.

Tools and Materials • Cylinder leakage tester • Spark plug socket • Stethoscope Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Check the oil level, and correct as needed.

h

2. Start the engine, and allow it to idle until the engine is moderately warm. Allow it to cool slightly before removing a spark plug.

h

3. Remove a spark plug from a cylinder (preferably one with low compression), and note its condition. Describe your results: __________________________________________________________ _________________________________________________________________________ 4. Rotate the engine until it is at TDC on the compression stroke on the test cylinder.

h

5. Apply shop air to the cylinder leakage tester, and adjust the tester to read 0 percent.

h

6. Install the cylinder leakage tester adaptor into the spark plug hole.

h

7. Connect the cylinder leakage tester adaptor in the spark plug hole to the leakage tester, and note the percentage of leakage: _________________________________________________________________________ Is this an acceptable amount of leakage? ________________________________________ 8. Use a stethoscope to listen at the oil dipstick. Describe your results: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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9. Use a stethoscope to listen at the intake manifold. Describe your results: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Use a stethoscope to listen at the tailpipe. Describe your results: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 11. Use a stethoscope to listen at the radiator fill. Describe your results: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 12. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 6

REPAIR AND REPLACEMENT OF ENGINE FASTENERS, GASKETS, AND SEALS

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■ ■■

How to inspect internal and external threads, and repair as needed. How to install a thread insert. How to replace engine gaskets.

■■ ■■

How to replace engine seals. How to choose and use sealant and ­liquid gasket makers properly.

Basic Tools Basic mechanic’s tools set Service information

Terms To Know Die Extractor

Self-tapping insert Tap

Thread insert

INTRODUCTION During the processes of removing an engine or performing major repairs, you are likely to experience broken bolts or damaged threads. Each fastener is important to proper vehicle and engine operation or it would not be used. It is important that each fastener have proper threads to hold securely. Also, gaskets, seals, and sealant and liquid gasket makers are used to contain engine fluids. Proper replacement of gaskets and seals is an integral part of engine repair. This chapter discusses the various methods of fastener removal and thread repair. You will learn how to install a thread insert. We will also discuss the proper replacement techniques for engine gaskets and seals, and cover the use of sealant and liquid gasket makers.

THREAD REPAIR At some time, every technician is frustrated because of a broken fastener or damaged threads. These must be repaired to provide proper clamping forces of the mating components. It is usually a lot faster to take the proper steps and precautions to prevent fastener breakage than it is to perform the repair procedures. Even with all steps taken, the fastener may still break. To help reduce the potential of fastener breakage and damage, the following offers some advice: 1. First, spray all fasteners with a penetrating oil before attempting to remove them. Using a little oil now may save lots of time later. A saying that can prevent a lot of problems later is, “The best time to use penetrating oil is before you need it.” The oil will work its way into the threads and dissolve the rust and corrosion. Also, the oil will lubricate the threads to aid in removal. Allow the oil to soak into the threads before attempting to remove the fastener.

Special Tools Stud remover Arc welder Nut splitter Left-hand twist drill bits Reversible drill Extractor set Tap and die set Thread insert repair kit

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Caution Make sure all bolt holes are clean and free of liquid before threading a screw or bolt; otherwise, the threaded component could be damaged due to the hydraulic pressure.

2. Next, be sure you are using the proper tools. Use a box-end wrench or socket that fits the fastener head snug. Avoid the use of open-end wrenches during disassembly. 3. If the fastener will not come loose with normal force, and you performed the first two steps, then make sure of the thread direction. Although not common on most engine applications, left-handed threads may be found on some parts such as fan clutch nuts, adjustable steering and suspension components, or wheel lug or hub nuts. If the fastener still does not loosen, remember, never force a fastener loose. The intent is to remove the fastener, not to break it off. If the fastener will not loosen using normal force, try to tighten the fastener slightly and then back it out. Sometimes this will break the corrosion loose and allow the fastener to be removed. 4. If the fastener still will not loosen, use a punch on the head of the bolt and strike it with a hammer. The shock may break the corrosion loose. 5. If the fastener still will not loosen, apply heat to the fastener. Use a minimal amount of heat; in most cases, a simple propane torch is sufficient. Heat either the fastener or the casting around the fastener, but not both. The trick is to get one component to expand more than the other; for example, if the nut on the end of a bolt will not loosen, heat the nut to get it to expand. If a bolt is stuck in the block, heat the casting to get the hole enlarged so the bolt can be removed. WARNING  Never use penetrating oil or spray lubricants on a fastener that has been heated and is still warm. Most of these materials are flammable and could result in a flare-up.

At this point, you are running out of options. Try heating the fastener with a torch, and while it is still hot, hold a piece of paraffin wax against the fastener, allowing the wax to run down and into the threads. Allow the wax to sit in the threads for a few minutes before attempting to remove the fastener. 6. If you are still unable to remove the fastener, it will probably need to be cut off and drilled out. These procedures are described in the discussion on the removal of broken bolts.

An extractor is a ­special tool that is used to remove a broken bolt from a bolt hole.

If the existing fastener cannot be removed due to a damaged head, several methods are available for removing the fastener: ■■ It may be possible to get a hold of the fastener with a stud remover (Figure 6-1). ■■ Use a chisel (Figure 6-2). Position the chisel off center of the fastener; then strike it with a hammer to drive the fastener in a counterclockwise direction. Do not use a chisel on a fastener seated against aluminum or sheet metal. ■■ Reverse splined socket-type extractors dig into the sides of rounded fasteners while trying to loosen. ■■ Use an arc welder to attach a rod to the head of the fastener. Then use locking pliers to turn the fastener out. ■■ If a nut is damaged, use a nut splitter to cut off the nut (Figure 6-3). ■■ Use a left-hand drill bit with a reversible drill and an extractor (Figure 6-4). ■■ Use an extractor by drilling a hole in the center of the fastener and tapping the extractor into the hole. Turn the extractor in the counterclockwise direction to remove the fastener (Figure 6-5). ■■ Drill out the center of the fastener using progressively larger drill bits until all that remains of the bolt is a thin skin. Peel the skin from the threads of the hole. If the fastener head is so badly damaged that a tool cannot be fitted onto it, and the preceding procedures do not work, the head usually must be cut off. This can be done with a die grinder and a cutting wheel. Be careful not to damage the casting area around

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Damaged bolt

Figure 6-2  Using a chisel and hammer to remove a damaged bolt.

Figure 6-1  A stud remover.

Cutter

Forcing screw

Screw head

Figure 6-3  A nut splitter for cutting off damaged nuts.

Figure 6-4  An extractor set.

Screw extractor

Broken bolt with hole drilled in the middle

Figure 6-5  Using an extractor to remove a broken bolt.

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Caution Chisel fasteners that are seated on iron castings only. Attempting to chisel a fastener on aluminum or stamped steel can result in damage to these components.

the fastener. Usually, removing the head will relieve the tension against the fastener and allow it to be removed by cutting a slot across the shank and using a standard screwdriver. If the fastener still will not loosen, an extractor may be needed. If the fastener head is broken off due to excessive torque or bottoming out in the hole, do not use an extractor to remove it. The extractor is made of very hard steel. Because of the hardness, it is very brittle and breaks easily. If the extractor should break off in the fastener, it is very difficult and time consuming to remove it. If an extractor should break off, do not attempt to drill it out. The drill bit will break off, leaving the extractor and the bit in the fastener. Special tap extractors can be used to remove some broken extractors. If an extractor is required, follow these steps: 1. Begin by using a center punch to mark the exact center of the fastener. This is the most important step. If the center punch is off center or the hole drilled at an angle, the extractor bit will have a greater potential of breaking. 2. Next, determine the largest size extractor you can use to remove the fastener. The larger, the better, but not so large as to damage the threads of the casting. The intent is to make the walls of the broken fastener as thin and flexible as possible so the fastener will lose its grip on the casting and allow the extractor to bite into the fastener better. Once the extractor size is determined, the correct size drill bit is selected. Most extractors will be stamped with the correct drill bit to use.   Using the correct size drill bit, drill a hole all the way through the center of the fastener. Use a drill guide if needed. If possible, use a left-hand drill bit, since it will sometimes draw the fastener out as the hole is drilled. For larger size fasteners, start with a small-size drill bit and work up to the correct size. 3. Once the hole is drilled, place the extractor into the hole and tap it lightly with a brass hammer. Make sure the extractor is straight into the hole. Tap (not pound) the extractor in just enough that the extractor will bite the wall of the drilled hole as it is turned. If you drive the extractor in too deep, the walls of the fastener will expand and cause the bond between the fastener and the casting to become even tighter. 4. Now use a tap wrench or open-end wrench to turn the extractor counterclockwise. Some kits come with a nut that fits over the extractor and the wrench fits over the nut. Never use power tools to turn the extractor, because it will probably break. SERVICE TIP  A common trick to remove a small piece of a broken tap is to use a center punch and hammer to deliver a sharp, hard blow to the tap. This will cause the tap to shatter into pieces, which can be removed with a magnet. Do not attempt this on a broken extractor. Extractors are harder than taps. Attempting to shatter one in this manner will cause it to wedge tighter into the drilled hole and make matters worse. If needed, take the component to a machine shop and have them remove the broken fastener for you. Some machine shops use a process called electrical discharge machining (EDM) to remove broken tools.

If the extractor begins to shear off, stop! It is a lot easier to remove an extractor that is in one piece than to remove a broken one. If the extractor does break, heat the drilled hole with a torch and then cool the broken extractor quickly by dripping water onto it (paraffin wax can also be used). Use a tap extractor to try to remove the broken extractor. Never attempt to drill out a broken extractor, all you will do is break the bit. An alternative to using extractors is to use a common set of Allen wrenches. Select an Allen wrench that is slightly smaller than the width of the broken fastener; for the tightest grip the bigger the Allen wrench size the better. Drill a hole through the bolt using a bit Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

size the same as the Allen wrench when measured across the flats. Tap the Allen wrench into the hole using a brass hammer. Usually, the corners of the Allen wrench will grip the fastener walls and cause the fastener to follow as the wrench is turned. It is also possible to remove a broken fastener by drilling it out. For this operation to work, the exact center of the bolt shank must be located and center punched. Starting with a small drill bit and working up, drill out the fastener until the last drill bit used is the same size as the minimum diameter of the fastener (the size bit used to tap the hole to fit the fastener). This will leave a very thin wall where the fastener used to be. Use a magnet or a pocket screwdriver to pick out the very thin wall of the fastener. If the exact center of the fastener is not drilled and the hole is off center, this process will not work. Internal thread damage can occur if the fastener is not properly installed or if corrosion has eaten away some of the threads. Damaged internal threads can usually be repaired using a thread chaser, tap, or thread inserts. Prior to making thread repairs, it is important to properly identify the pitch, size, and length of the fastener to be used. Thread chasers can be used to clean internal and external threads. Thread files can be used to remove burrs from external threads (Figure 6-6). Thread chasers and thread files can be used to clean and repair minor thread damage. These tools are designed to roll the threads back to their original shape, instead of cutting new threads. Thread chasers, taps, or dies should be used to clean the threads of every fastener used on the engine during the rebuilding process. If the threads cannot be restored by use of a thread chaser, it may be possible to use a tap or die to repair the damaged threads (Figure 6-7). Proper size selection is important. Use a thread pitch gauge to determine the correct pitch (Figure 6-8). Internal threads can be located in through holes or blind holes (Figure 6-9). Through holes are threaded using a taper tap, while bottoming taps are used for blind holes (Figure 6-10).

Figure 6-6  A thread file will refinish lightly damaged threads.

A tap is a special tool used to thread openings in metal components. A die is a special tool that is used to clean threads or make new threads on a bolt.

Thread chasers can be used to repair minor thread ­damage by rolling threads back to their original shape.

Figure 6-7  A master tap and die set with metric and standard equipment. Through hole

Blind hole

Figure 6-8  Use a pitch gauge to determine the correct ­selection of tap.

279

Figure 6-9  Comparison of through and blind holes.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 6-10  Two different types of taps. The tapered tap is used for through holes, and the bottoming tap is used for blind holes.

Chamfer

Figure 6-11  Chamfering the hole removes the raised edge.

WARNING  Wear proper eye protection whenever using a tap or die. These tools are very brittle and may shatter.

Once the correct tap or die is selected, the following guidelines should be adhered to: Thoroughly clean the hole or bolt. Lubricate the tap or die with cutting oil. ■■ Start the tap or die onto the existing threads, being careful to start the tool straight. ■■ Use the correct holding wrench for the tap. ■■ Chamfer the hole after the threads are repaired (Figure 6-11). If a fastener had to be removed and all of the threads were damaged, it may be possible to drill out the hole and tap it to fit a larger fastener. This usually works for such things as attaching bolts for the exhaust manifold to the cylinder head; however, if larger bolts are used, consider these before beginning; there must be enough casting to support the larger fastener, and the attaching component (i.e., exhaust manifold) may need to be drilled to accept the larger bolt. If it is determined that using a larger bolt is indeed the less expensive and time-­ consuming method of thread repair, and there are no interferences in the casting to ­prevent it, the first step is to determine the size of the fastener that will be used. Once the fastener size is determined, the size of drill bit needs to be selected. Usually, the tap kit will have a tap drill size chart that indicates the correct size bit for the tap. A drill tap ­usually provides about 75 percent of a full thread. If a chart is not available, thread the correct size nut onto the bolt that will be used. Once the correct nut is determined, use it to select the drill bit by using the largest bit that will fit into the nut. Using too large of a bit will result in the tap not cutting threads that will be deep enough to hold the fastener properly. Too small of a bit makes cutting the threads difficult. Once the proper size hole is drilled, it is then tapped. When tapping the hole, advance the tap a few turns and then back it off one-quarter turn. When cutting any metal other than iron, lubricate the tap with cutting oil, and keep it well lubricated throughout the operation. Iron can be tapped without the use of oil. Continue to advance and back off the tap until the hole is completely threaded. Steps to remove a broken bolt and clean the threads using a tap are outlined in Photo Sequence 13. If it is not possible to enlarge the fastener size, the original size will have to be restored using a form of thread insert (Figure 6-12). Several different types of thread inserts are available: ■■ Helical inserts ■■ Self-tapping inserts ■■ Key-locking inserts ■■ Chemical thread repair ■■ ■■

A thread insert may be called a heli-coil.

The thread insert allows for major thread repairs while keeping the same size fastener.

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Hexed-head cap screw

Thread insert

Damaged thread

Figure 6-12  A thread insert replaces the damaged threads without having to change the size of the fastener.

PHOTO SEQUENCE 13

Removing a Broken Bolt and Using a Tap

Broken Off Bolt

P13-1  This bolt broke off in the block and must be extracted.

P13-4  Center the drill carefully, and drill a hole to use the bolt extractor.

P13-2  A stud extractor was used but could not get enough of a bite to remove the broken bolt.

P13-5  Lightly tap the thread extractor into the drilled hole. Do not drive it in too far or you will tighten the bolt threads in the hole.

P13-3  Select the correct size drill to match the bolt extractor suitable for the broken bolt.

P13-6  Turn the thread extractor counterclockwise, and hopefully the broken bolt will come with it.

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PHOTO SEQUENCE 13 (CONTINUED)

P13-7  With the broken bolt removed, clean the threads with a tap.

P13-10  Lightly lubricate the threads of the new bolt.

P13-8  Use the correct size tap, and use a light touch to clean the threads of the hole.

P13-9  Clean the bolt hole of any metal filings. Be sure you have safety glasses on!

P13-11  Start the bolt in by hand to be sure it turns freely.

Helical inserts are made from stainless steel and look like a small spring. Installing a helical insert is a four-step process (Figure 6-13). First, the damaged hole is enlarged to a specified size. The drill bit size depends on the size of the insert and is supplied by the manufacturer. If necessary, install a stop collar on the drill bit to prevent it from drilling too deep. Second, clean the hole out thoroughly, and then tap the hole. Use the tap size specified by the manufacturer. The tap is a special tap for use with inserts. The large diameter and course pitch are not standard patterns for the fastener that will be installed. Do not attempt to substitute this tap with a regular one. Clean the hole again. The third step is to place the insert onto the mandrel and engage the tang of the insert onto the end of the mandrel. Next, apply a light coating of thread locking compound to the external threads of the insert and thread it into the hole. Once the insert is started into the hole, spring pressure will prevent it from unscrewing. Once started, the insert cannot be removed. When correctly installed, the insert should be one-quarter to one-half turn below the surface. If the hole is deeper than the length of a standard insert, thread the insert down far enough to allow a second insert to be threaded in on top of the first. If the hole is too shallow for the length of the insert, cut the insert to the proper length prior to installing it onto the mandrel. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

1. Drill hole to proper size

3. Tap hole to proper size

283

2. Install insert on mandrel

4. Install insert into threaded hole

Figure 6-13  The four steps to installing a thread insert.

SERVICE TIP  Placing a rubber hose over the drill bit works to prevent the bit from going too deep. Cut the hose so the desired depth of the hole is equal to the amount of exposed drill bit.

Remove the mandrel by unscrewing it from the insert. Use a small punch to break off the tang at the bottom of the insert. Another variation of the threaded insert is the self-tapping insert. These inserts are good to use in blank holes since they cut their own thread. Cutting their own thread eliminates the need of tapping the hole after it is drilled. The process of installing selftapping inserts is the same as the helical insert. Solid bushing inserts are also available. These inserts use a machine thread, so a standard tap may be used. All other installation steps are the same as with helical inserts. Some inserts are held in place by small keys. Key-locking inserts are similar to solid bushing inserts, except after they are installed, the keys are driven into place (perpendicular to the threads) to prevent the insert from coming out. Inserts for repairing spark plug holes are also available. The installation is the same as discussed previously; however, some spark plugs use a tapered seat, while others use a flat seat with a gasket. Be sure to install the correct insert that matches the spark plugs to be used.

A self-tapping insert provides a new thread when installed in an opening with damaged threads.

CUSTOMER CARE  If you have to install a thread insert into a spark plug hole, you should inform the customer. If something ever happens to the insert and the customer doesn’t know that the hole had previously been damaged, they could become angry and distrustful of your work.

Finally, some threads can be repaired using epoxies. Epoxies cannot be used to repair threads in high-stress, high-torque components. Epoxy should not be used to repair the threads of critical clamping force areas such as cylinder heads, intake manifolds, and internal engine parts. Epoxy thread repair kits usually contain a two-part epoxy and a releasing agent. To use the epoxy, first clean and dry the threads of the hole and the fastener ­thoroughly. Apply a very thin coat of the releasing agent to the threads on the fastener, ­covering the entire thread surface area. Mix together the two-part epoxy (resin and Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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hardener), making sure there will be enough mixed to complete the job. Spread the epoxy as evenly as possible on the inside of the hole. If the hole goes through the casting, use tape to shut off one end of the hole so the epoxy does not run out. Screw the fastener into the hole, but do not tighten it. Allow the epoxy to cure the required amount of time specified in the instructions. After the epoxy dries, tighten the bolt.

GASKET INSTALLATION For the gasket to perform its function, it must be installed correctly. There are a few basic steps to follow when preparing to replace a gasket:

Special Tools Torque wrench



1. Follow all instructions provided by the gasket manufacturer. 2. Thoroughly clean the mating surfaces. 3. Check the gasket for proper fit. 4. Never reuse gaskets.

Many gaskets are installed dry without additional sealants. Never use sealant unless the manufacturer specifies it; then follow the instructions closely. Most gasket and seal failures are caused by improper installation. When installing a gasket, you need to torque the cover or component on properly. Overtightening a cork gasket, for example, will cause the gasket to crack. Unequal torque on any gasket is likely to allow leakage. Use the recommended torque sequence. If one is not provided, tighten the bolts in a diagonal pattern starting at the inside and working your way out. Use a torque wrench and tighten the bolts to the proper specification. Do not use air tools to tighten gasket covers. SERVICE TIP  No-retorque gaskets are available for most engine applications; however, many imports and older engines require the cylinder head to be retorqued. This is required because the original set of the gasket occurs after initial engine operation and then relaxes. This causes the clamping pressure to be decreased. Retorquing the bolts will reset the proper clamping pressure.

SERVICE TIP  If the seal is stubborn, drill two small holes 180 degrees apart on the metal outer ring of the seal. Thread self-tapping sheet metal screws into the holes; then grip the screws with pliers or side cutters and pry the seal out.

CYLINDER HEAD GASKET INSTALLATION Cylinder head gaskets must be capable of withstanding combustion pressures up to 2,700 psi (1,862 kPa) and temperatures over 2,000°F (1,100°C ). Proper installation will ensure the gasket will withstand these conditions. Following is a typical procedure for cylinder head gasket replacement: 1. Check the gasket for proper fit. Note that the gasket may be marked for proper installation. 2. Clean and prepare the bolts. Make sure all guides or dowel pins are in place (Figure 6-14). 3. Install the gasket and cylinder head. 4. Follow the service manual torque sequence, and torque the bolts to specifications. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

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Block

Dowel must be bottomed out

Gasket

Dowel (2 required)

Figure 6-14  Some engines use dowel pins to guide the head and gasket.

Apply liquid gasket here

Oil pan gasket

Figure 6-15  Remove the deformation around the bolt holes of the valve cover before installing it.

Oil pan

Figure 6-16  Oil pan and gasket installation.

OIL PAN GASKET INSTALLATION When an engine is rebuilt or replaced or when the oil pan gasket is leaking, install a fresh gasket under the oil pan. When the job is done with the engine in the car, it may be necessary to remove some portions of the frame, suspension, or exhaust. One of the most important things to do when replacing a gasket is to be certain that all of the old gasket and any oil is removed from the engine block and from the oil pan. If the oil pan is stamped steel, it may be necessary to straighten deformities around the bolt holes. Use a ball peen hammer and a block of wood to flatten the bolt holes (Figure 6-15). Do not attempt this method on an aluminum oil pan; it will crack. Next, line up the new gasket on the pan, and be sure it fits properly. Locate the service procedure or gasket instructions to determine if any sealant or liquid gasket maker should be used (Figure 6-16). Locate and follow the torque sequence and specification to tighten the oil pan. Check for leaks after the engine has started.

VALVE COVER GASKET REPLACEMENT A common source of oil leaks is from the valve cover gasket(s). Replacement of these gaskets is typically straightforward, although on some vehicles it may be necessary to remove a number of components to gain access to the cover. The general procedures are very similar to those for replacement of an oil pan gasket. One of the leading causes of gasket failure is improper installation, so be certain to follow the manufacturer’s procedures for tightening the cover and for using any sealant on the gasket. Photo Sequence 14 shows typical steps involved in removing and replacing a valve cover gasket on a modern pickup truck.

Caution If the outer ring of the seal is coated with a silicone from the factory, do not use oil to aid in installation. The oil may not be compatible with the silicone and may cause leakage. Use soapy water to aid installation.

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PHOTO SEQUENCE 14

Replacing a Valve Cover Gasket

Leaking valve cover gasket

P14-1  After identifying the problem, consult the service information for instructions on how to replace the valve cover gasket properly.

P14-2  Remove the air distribution ductwork to gain access to the valve cover.

P14-3  Remove and label connectors and vacuum lines as needed.

P14-4  With the intake ducts out of the way, remove the spark plug wire loom and wires that will obstruct removal.

P14-5  Loosen the valve cover bolts using the proper sequence if one is specified.

P14-6  Maneuver the valve cover off of the cylinder head.

P14-7  Remove the old gasket material, and thoroughly clean and dry the valve cover.

P14-8  Install the new valve cover gasket securely. Use liquid gasket maker only if it is specified.

P14-9  Always properly torque the valve cover to the specification to ensure a quality repair.

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PHOTO SEQUENCE 14 (CONTINUED)

P14-10  Reinstall the ductwork securely.

P14-11  Reconnect all wiring and vacuum lines. Wipe down the valve cover and surrounding components. Finally, start the vehicle and check to be sure it runs properly and has no leaks.

SEAL INSTALLATION Most one-piece seals are removed by prying them out of the bore (Figure 6-17). When performing this task, care must be taken not to damage the bore. A special seal-removing tool may be required to remove the seal if it is recessed into the bore (Figure 6-18). Prior to installing a seal with a steel outer ring, coat the outer surface with a silicone sealer. The seal lip must always face toward the flow of lubricant. Use a seal driver or press of the proper size to install the seal (Figure 6-19). Support the back of the component where

Figure 6-17  Prying out the old seal.

Figure 6-18  Use a seal remover to pry the old seal out.

Seal driver

Figure 6-19  Driving in a new seal. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 6-20  Apply liquid gasket maker around any bolt holes or passages.

the seal is being installed, if possible, to prevent warpage or breakage. Do not use excessive force to install the seal. Drive the seal until it is the proper depth into the bore, as specified in the service manual. Coat the rubber seal with engine oil to protect it on initial startup.

Caution Do not use a sealer or liquid gasket maker on a gasket unless specified in the service manual.

USING ADHESIVES, SEALANTS, AND LIQUID GASKET MAKERS

Caution Make sure all gasket makers and sealers used on the engine and support systems are “Sensor Safe” so they do not damage the O2 sensors.

Caution Always check the expiration date on the sealant and liquid gasket makers before using it. Most sealants have a shelf life of one year. If the sealant or liquid gasket maker is too old, it may not set correctly.

There are several locations on the engine where sealants and liquid gasket makers are used. The proper liquid gasket maker must be selected for the application. Aerobic sealers, such as room-temperature vulcanizing (RTV) liquid gasket makers, are used on flexible metal flanges. Anaerobic sealers are used between two machined metallic surfaces. Before applying any type of sealer, the surface must be properly prepared. Use a flat-blade putty knife, scraper, or wire brush to clean all of the gasket surfaces. Inspect the surfaces for warpage, dents, and old gasket materials. Wipe the surfaces free of dirt and oil. Apply RTV liquid gasket maker in a 1/8-in. (3-mm) diameter continuous bead. Circle any bolt holes or fluid passages (Figure 6-20). For corner sealing, place a 1/8-to 1/4-in. (3-mm to 6-mm) drop in the center of the contact area. Use a shop towel to wipe away any gasket maker that expands out of the seam. RTV begins to cure in about 10 minutes, requiring all components to be installed and torqued before the gasket maker cures. RTV is not used in addition to a gasket. In some cases, it is used at the mating corners where gaskets connect, such as the ends of two-piece intake manifold gaskets on V-type engines. Be careful not to use too much RTV; more is not better. Using excess RTV can allow it to be drawn into the engine and clog critical fluid passages. Make sure to carefully follow the RTV manufacturer’s directions on total curing time before putting the gasket to the test. Apply anaerobic liquid gasket maker in continuous beads about 0.04 in. (1-mm) in diameter. Apply the gasket maker to only one gasket surface, making sure to circle any mounting hole or passages. Install the components and torque within 15 minutes.

CASE STUDY A student brought an engine to be overhauled into school. He had rebuilt the engine over the summer, but it started knocking just a few hundred miles later. Once the oil pan was removed, we could see the cause. The oil pickup screen was completely plugged with RTV. He had covered the oil pan gasket with RTV, thinking that it would provide the best seal.

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289

CASE STUDY When replacing a cracked exhaust manifold on a vehicle, a technician ran into some very rusty hardware (Figure 6-21). Some of the threads on the studs had actually rusted away. Rather than rethread the existing studs and risk having the nuts loosen up over time, the technician did the right thing and replaced the studs. She sprayed the studs generously with penetrating oil and let them sit before using the stud remover to extract the studs. Only one stud gave her trouble, but with a little heat to the head, it did break free and turn out.

Very rusted and corroded exhaust manifold studs and nuts

Figure 6-21  These very rusty nuts and studs required heat to extract them from the cylinder head.

ASE-STYLE REVIEW QUESTIONS 1. Technician A says to use a socket or a box-end wrench to loosen tight bolts. Technician B says to use locking pliers to free up rusted bolts. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Technician A says to heat a rusted nut and then spray penetrating oil on it. Technician B says you can use a nut splitter to remove damaged nuts. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

2. A bolt will not loosen: Technician A says to tighten the bolt slightly. Technician B says to rap the head of the bolt. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

5. A bolt head is damaged, and it won’t turn out. Technician A says that you can use a stud remover. Technician B says that you can use a center punch. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says to spray penetrating oil on rusty bolts before trying to loosen them. Technician B says to apply wax to the head of the bolt. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. To use an extractor, Technician A says to drill a hole into one side of the bolt. Technician B says to tap the extractor into the hole and turn it counterclockwise. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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7. An extractor broke inside a bolt. Technician A says to drill it out using a left-hand drill. Technician B says to heat the extractor and chisel it out. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that the sealing surfaces must be perfectly clean before fitting a new gasket. Technician B says that most gaskets should be ­lubricated with oil before installation. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

9. Technician A says that you should use RTV between two machined surfaces. Technician B says that anaerobic liquid gasket maker hardens within five minutes. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that you should apply a thin layer of RTV to the lip of a seal. Technician B says that you can use a chisel to get a stubborn seal out. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. While discussing thread insert installation, Technician A says that the first step is to use a tap to match the external threads on the heli-coil. Technician B says that the thread insert should be installed using the correct size drill bit. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. When using RTV for gasket applications: A. The gasket surface should be cleaned with acid. B. The RTV should be placed on the inside of the bolt holes. C. The RTV should be allowed to cure for 15 minutes before assembly. D. The RTV bead should be 1/8 in. (3 mm) in width.

4. Technician A says that you should spray head ­gaskets with copper sealer before installation. Technician B says that most head gaskets have a top marking on them. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that you can use a 1/4-in. drive air ratchet to install the oil pan. Technician B says to tighten the corners first and work your way in. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

3. While discussing seal installation, Technician A says that a seal lip should face toward the flow of lubricant it is sealing. Technician B says to tap around the edges of the new seal to fit it into place. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

Name ______________________________________

Date __________________

IDENTIFYING ENGINE FASTENERS AND TORQUE SPECIFICATIONS Upon completion of this job sheet, you should be able to properly identify the properties of common engine fasteners and their torque specifications. NATEF Correlation This job sheet addresses the following RST task: Tools and Equipment, Task # 2, Identify standard and metric designation. Tools and Materials • Service manual • Technician’s tool set • Torque wrench • Thread pitch gauge set • Dial caliper Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Your instructor will show you which fasteners should be removed from the engine. Remove each of the fasteners as directed. Then find the length, width, thread pitch, designation (metric or SAE), and torque specification. After you identify each fastener, reinstall them using a torque wrench to the manufacturer’s specification. 1. Fastener location_____________________________________________________________ Thread length __________________________ Total length __________________________ Thread pitch ___________________________ Designation __________________________ Torque specification _____________________ Socket size __________________________ 2. Fastener location_____________________________________________________________ Thread length __________________________ Total length __________________________ Thread pitch ___________________________ Designation __________________________ Torque specification _____________________ Socket size __________________________ 3. Fastener location_____________________________________________________________ Thread length __________________________ Total length __________________________ Thread pitch ___________________________ Designation __________________________ Torque specification _____________________ Socket size __________________________ 4. Fastener location_____________________________________________________________ Thread length __________________________ Total length __________________________ Thread pitch ___________________________ Designation __________________________ Torque specification _____________________ Socket size __________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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5. Fastener location_____________________________________________________________ Thread length __________________________ Total length __________________________ Thread pitch ___________________________ Designation __________________________ Torque specification _____________________ Socket size __________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

Name ______________________________________

Date __________________

LOOSENING A RUSTED FASTENER Upon completion of this job sheet, you should be able to remove a frozen fastener. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.7. Perform common fastener and thread repair, to include: remove broken bolt, restore internal and external threads, and repair internal threads with thread insert. This job sheet addresses the following MLR task for Engine Repair: A.6. Perform common fastener and thread repair, to include: remove broken bolt, restore internal and external threads, and repair internal threads with thread insert. Tools and Materials • Technician’s tool set • Heat source (if needed) • Tap and die set • Threaded insert set with lubricant Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure 1. Locate a damaged or seized fastener as guided by your instructor. Is your fastener a damaged nut, bolt, or stud? _________________________________________________________________________ 2. Spray penetrating oil on the fastener, and allow it to soak in. 3. Will your fastener loosen with a socket or box-end wrench? _______________________ _________________________________________________________________________ 4. Describe your next strategy for loosening the fastener. ____________________________ _________________________________________________________________________ Did that loosen the fastener? __________________________________________________ 5. Describe your next strategy for loosening the fastener. ____________________________ _________________________________________________________________________ Did that loosen the fastener? __________________________________________________ 6. Describe your next strategy for loosening the fastener. ____________________________ _________________________________________________________________________ Did that loosen the fastener? __________________________________________________

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7. If the fastener head is damaged, use a stud remover or an extractor to remove the fastener.

Task Completed

Describe your procedure and your results. ______________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Describe any additional steps required to remove the seized fastener. _______________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 9. Were you successful in removing the frozen fastener? _____________________________ 10. After removing the bolt, identify and use the correct tap to clean the threads of the hole. Do the same with a die for the old bolt. Note: You should replace the bolt if you used heat to remove it. 11. If the hole threads are damaged beyond repair, you will need to use a threaded insert. Start by drilling the hole to the proper size as indicated in the threaded insert kit.

h

12. Tap the new hole with the appropriate size cutting tap.

h

13. Apply locking compound to the threaded insert, and screw the new threaded insert into the hole.

h

14. Reassemble the components that are necessary, and install the bolt (new or old) into the new hole. Torque it to the specification.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Repair and Replacement of Engine Fasteners, Gaskets, and Seals

Name ______________________________________

Date __________________

295

JOB SHEET

43

REPLACING AN OIL PAN GASKET Upon completion of this job sheet, you should be able to properly replace the oil pan gasket. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.5.

Install engine covers using gaskets, seals, and sealers as required.

This job sheet addresses the following MLR task for Engine Repair: A.4.

Install engine covers using gaskets, seals, and sealers as required.

Tools and Materials • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

1. Locate the manufacturer’s procedure for removing and replacing the oil pan

h

2. Drain the oil, and remove the oil pan.

h

3. Clean the oil pan and the engine block of oil and old gasket material.

h

4. Lay the new gasket on the oil pan, and be sure the holes line up properly.

h

5. What type of gasket is used? __________________________________________________ _________________________________________________________________________ 6. Apply the recommended liquid gasket maker to the oil pan if applicable. What liquid gasket maker is recommended and where for your installation? ____________________ _________________________________________________________________________ 7. Install the new gasket, and tighten the oil pan using the appropriate sequence and torque specification. What is the torque specification for the oil pan attaching bolts? _________________________________________________________________________ 8. If working on an engine in a vehicle, replace the oil filter and reassemble the vehicle.

h

9. Refill the engine with the proper oil. What is the recommended oil? ________________________________________________ What is the engine oil capacity? ________________________________________________ 10. Start the engine, if applicable, and check for leaks. Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Repair and Replacement of Engine Fasteners, Gaskets, and Seals

Name ______________________________________

Date __________________

IDENTIFYING ENGINE MATERIALS Upon completion of this job sheet, you should be able to identify various engine materials and components used on late-model vehicles. Tools and Materials • Service information Procedure 1. Locate an engine that uses a cast-iron block and an aluminum cylinder head. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ 2. Locate an engine that uses an aluminum block and an aluminum cylinder head. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ 3. Locate an engine that has a lost foam casting block. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ 4. Locate an engine that uses a cast aluminum oil pan. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ 5. Locate an engine that uses a composite intake manifold. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ 6. Locate an engine that uses a cast-iron block and a cast-iron cylinder head. Describe the vehicle: Year ____________________ Make ___________________ Model ____________________ VIN ___________________________ Engine type and size __________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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JOB SHEET

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 7

INTAKE AND EXHAUST SYSTEM DIAGNOSIS AND SERVICE

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■

■■ ■■ ■■ ■■

How to service and replace air filters. How to diagnose drivability problems resulting from intake system vacuum leaks.

■■

How to use a vacuum gauge to ­diagnose engine problems. How to test the intake system for ­vacuum leaks. How to remove, inspect, and replace intake manifolds and gaskets. How to perform an exhaust system inspection.

■■

■■

■■ ■■ ■■

How to perform an exhaust system restriction test. How to remove and replace exhaust system components. How to test catalytic converters. How to inspect the turbocharger system. How to inspect the supercharger system. How to test for proper boost and boost control.

Basic Tools Service manual Technician’s tool set Penetrating oil Threadlock

Terms To Know Airflow restriction indicator Boost pressure Catalytic converter Diesel exhaust fluid (DEF) Diesel particulate filter Digital pyrometer

Front pipe Intake manifold Muffler Prelubrication Quick disconnect fittings Restricted exhaust

Supercharger Tailpipe Turbocharger Vacuum gauge Wastegate

INTRODUCTION The intake system must conduct the airflow into the cylinders without leaking or providing excessive airflow restriction. A small leak in the air intake duct between the air cleaner and the throttle body allows dirt particles to enter the air intake, which greatly reduces engine life. On an engine that uses a mass airflow sensor, a leak between the MAF and the intake manifold will allow air that is not measured (false air) to enter the engine. The PCM will “think” less air is flowing into the engine and will deliver less fuel than is required. This can cause serious drivability issues, such as hesitation and misfiring during acceleration. A leak between the throttle body and the intake valves allows air to be drawn into the intake manifold, and this action causes a lean air-fuel ratio, which results in performance problems such as engine surging at low speed. The exhaust system must carry the exhaust gases from the cylinders to the atmosphere without excessive restriction or noise. A restricted exhaust system results in a power loss at higher speeds. Accurate intake and exhaust system diagnosis and service is essential to provide proper engine performance and economy. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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When a turbocharger or supercharger system malfunctions, it can create an underboost or overboost condition. When too little boost is developed, the engine will lack its normal power and the engine will hesitate on acceleration. When the overboost control system malfunctions and too much boost is allowed, serious engine damage can occur; prompt repairs are essential.

AIR CLEANER SERVICE

Special Tools Vacuum gauge Vacuum pump Ultrasonic vacuum leak detector Smoke-type vacuum leak detector Splitting tool Digital pyrometer

If an air filter is doing its job, it will get dirty. That is why filters are made of pleated paper. The paper is the actual filter. It is pleated to increase the filtering area. By increasing the area, the amount of time it will take for dirt to plug the filter becomes longer. As a filter gets dirty, the amount of air that can flow through it is reduced. This is not a problem until less air than the engine needs flows through the filter (Figure 7-1). Without the proper amount of air, the engine will not be able to produce the power it should, nor will it be as fuel efficient as it should be. An engine with a plugged air filter will hesitate on acceleration and may not reach cruising speeds. Usually the engine will not misfire; it will just feel as though the engine does not respond to the accelerator pedal. When it is severely plugged, the engine may not start or will stall after starting. Included in the preventive maintenance plan for all vehicles is the periodic replacement of the air filter. This mileage or time interval is based on normal vehicle operation. If the vehicle is used or has been used in heavy dust, the life of the filter is shorter. Always use a replacement filter that is the same size and shape as the original. Follow these steps for air filter service or replacement: 1. Remove the wing nut, clips, or screws that retain the air filter cover, and remove the cover. You may also need to remove the intake ductwork (Figure 7-2).

MAF sensor

Air filter housing Retaining clip

Figure 7-1  This air filter was causing a significant hesitation on acceleration.

Figure 7-2  You have to remove the intake duct and the MAF sensor to replace this air filter.

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Intake and Exhaust System Diagnosis and Service

301

Lid

Element

Air cleaner housing

Figure 7-3  Air filter and air cleaner housing.

INH2O 25 22 15 11 8

Figure 7-4  Airflow restriction indicator.

2. Remove the air filter element from the air cleaner, and be sure that no foreign material such as small stones drop into the air cleaner duct or throttle body (Figure 7-3). If the air cleaner has an airflow restriction indicator, inspect the color of the indicator window (Figure 7-4). If the window appears orange and “Change Air Filter” appears, the air filter is restricted. When the window appears green, the air filter is not restricted. If the airflow restriction indicator window appears orange, press the reset button on top of the indicator to reset the indicator so green appears in the window. 3. Carefully clean the air cleaner housing to remove any small stones, bugs, and debris. Inspect the air cleaner housing for cracks, holes, and damage. 4. Visually inspect the air filter for pinholes in the paper element and damage to the paper element, sealing surfaces, or metal screens on both sides of the element. If the air filter is damaged or contains pinholes, replace the filter. 5. Place a shop trouble light on the inside surface of the air filter, and look through the filter toward the light. The light should be clearly visible through the filter, but there must be no pinholes in the paper element. If the light is not visible over most of the filter, or the filter is contaminated with oil, the air filter must be replaced. If the air ­filter is contaminated with oil, the engine has excessive blowby past the piston rings, or the positive crankcase ventilation (PCV) valve or hose is restricted (Figure 7-5). When either of these conditions exists, excessive crankcase pressure forces oil vapors out of the engine through the PCV clean air hose into the air cleaner. Clean air should normally flow from the air cleaner through the PCV clean air hose into the engine.

The airflow ­restriction indicator displays the amount of air filter ­element restriction.

When servicing an air filter, always service the positive crankcase ventilation (PCV) inlet filter.

SERVICE TIP  Rodents often plug up air filters and air filter housings by s­ toring food in them. Rodents are attracted to the warmth of the engine. Check underneath a filter for dog food, nuts, or bedding.

6. Clean or replace the PCV system filter in the air cleaner. 7. Install the replacement air filter in the air cleaner housing. Be sure the sealing surfaces on the element fit snugly on the air cleaner housing. Install the air cleaner cover, and tighten the retaining clamps, screws, or wing nut. 8. Be sure the PCV hose and any other hose sensors or wiring connectors are properly connected to the air cleaner.

Caution Do not use pressurized air to clean the housing unless you are sure that debris will not get into the engine or other compartments.

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PCV Tube

Figure 7-5  The PCV tube is sometimes connected to the air intake tube.

VACUUM SYSTEM DIAGNOSIS AND TROUBLESHOOTING Vacuum system problems can produce or contribute to the following drivability symptoms: 1. Stalls 2. Poor fuel economy 3. Detonation, or knock or pinging 4. Rich or lean stumble 5. Rough idle 6. Poor acceleration 7. Backfire (deceleration) 8. Overheating 9. Hard start (hot soak) 10. Rotten eggs exhaust odor 11. No start (cold) As a routine part of problem diagnosis, a technician who suspects a vacuum problem should first do the following: 1. Inspect vacuum hoses for improper routing or disconnections (engine decal identifies hose routing). 2. Look for kinks, tears, or cuts in vacuum lines. 3. Check for vacuum hose routing and wear near hot spots, such as exhaust manifold or the EGR tubes. 4. Make sure there is no evidence of oil or transmission fluid in vacuum hose connections. (Valves can become contaminated by oil getting inside.) 5. Inspect vacuum system devices for damage (dents in cans, bypass valves, broken nipples on vacuum control valves, broken tees in vacuum lines, and so on). Broken or disconnected hoses allow vacuum leaks that admit more air into the intake manifold than the engine is calibrated for. The most common result is a rough-running engine due to the leaner air-fuel mixture created by the excess air. Kinked hoses can cut Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Intake and Exhaust System Diagnosis and Service

off vacuum to a component, thereby disabling it. For example, if the vacuum hose to the EGR valve is kinked, vacuum cannot be used to move the diaphragm. Therefore, the valve will not open.

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Classroom Manual Chapter 7, page 149

SERVICE TIP  Do not clean air filters with shop air. This can break holes in the filter element and allow large particles into the engine, potentially causing serious damage. If the air filter is dirty, replace it; air filters generally are not terribly expensive.

To check vacuum controls, refer to the service manual for the correct location and identification of the components. Typical locations of vacuum-controlled components are shown in Figure 7-6. Tears and kinks in any vacuum line can affect engine operation. Any defective hoses should be replaced one at a time to avoid misrouting. Original equipment manufacturers’ (OEM) vacuum lines are installed in a harness consisting of ⅛-inch (3.18 mm) or larger outer diameter and 1 17-inch (1.59 mm) inner diameter nylon hose with bonded nylon or rubber connectors. Occasionally, a rubber hose might be connected to the harness. The nylon connectors have rubber inserts to provide a seal between the nylon connector and the component connection (nipple). In recent years, many domestic car manufacturers have been using ganged steel vacuum lines.

To fuel tank

EVAP purge solenoid

Special Tools Vacuum gauge Smoke leak detector

To brake booster EGR transducer

Crankcase breather

To air cleaner

EVAP canister

M

EGR valve

Throttle body PCV valve

M

Check valve w/orifice Engine valve cover

To climate control, cruise control, 4WD axle (when equipped)

Intake manifold

Engine valve cover

Figure 7-6  Typical vacuum devices and controls. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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A vacuum gauge is designed to read intake manifold vacuum.

An intake manifold vacuum leak causes a low, steady reading on a vacuum gauge connected to the intake manifold. It may also cause a rough or high idle condition. The vacuum in the intake manifold operates many systems, such as emission controls, brake boosters, heater/air conditioners, and cruise control. Classroom Manual Chapter 7, page 149

Special Tools Vacuum pump Smoke-type vacuum leak detector

VACUUM TESTS The vacuum gauge is a very important engine diagnostic tool used by technicians. With the gauge connected to the intake manifold and the engine warm and idling, watch the action of the gauge needle. A healthy engine will give a steady, constant vacuum reading between 17 and 22 inch Hg (57.5 and 74.4 kPa) (Figure 7-7). On some four- and sixcylinder engines, however, a reading of 15 inch Hg (50.7 kPa) is considered acceptable. With high-performance engines, a slight flicker of the needle can also be expected. Keep in mind that the gauge reading will drop about 1 inch (2.54 cm) for each 1,000 feet (305 m) above sea level. Figure 7-8 shows some of the common readings and what engine malfunctions they indicate. If your vacuum test or other symptoms indicate a vacuum leak, further testing may be needed to isolate the location of the leak. Vacuum can leak from a faulty intake manifold gasket, a cracked intake manifold, faulty injector O-rings, or from a vacuum line. The most effective method to test for a vacuum leak is with a smoke leak detector (Figure 7-9). You can connect the tester through the throttle bore and then depress the push button to introduce smoke into the intake system. If there is a leak in the system, you will see smoke emitted from the source of the leak (Figure 7-10). A flashlight or a light provided by the smoke machine’s manufacturer will assist you in finding smaller and hard-to-see vacuum leaks. Another method of testing for vacuum leaks is to use a propane tank with a lowpressure outlet line (Figure 7-11). First verify that there are no sources of ignition in or around the engine compartment. Then with the engine running, direct a small amount of propane at potential areas of leakage. When the propane is introduced toward a vacuum leak, the engine will pull the added fuel in and the idle quality will change. Turn the propane on and off at the site of the leak to confirm your suspicion. Be careful to perform this procedure in a well-ventilated area, and avoid using any more propane than is needed for diagnosis.

15 10

15 10

20

5

25 0

5

25 0

30 Manifold leak

15

5

25

30 Burnt or leaking valves

Figure 7-7  This engine has a healthy 18 in. Hg vacuum at idle.

10

20

0

30 Weak valve springs

15 10

20

20

5

25 0

30 Sticking valves

Figure 7-8  Vacuum gauge readings and the indicated engine conditions.

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Intake and Exhaust System Diagnosis and Service

Smoke billowing from the leaking intake manifold gasket

305

Smoke leak detector adaptor

Figure 7-10  This smoke test shows a serious leak at the intake manifold gasket. Figure 7-9  A smoke leak detector can be used to find intake or exhaust system leaks as well as evaporative emissions system leaks.

Figure 7-11  A small propane tank with a pressure control nozzle makes an excellent and inexpensive vacuum leak detection tool.

INTAKE MANIFOLD SERVICE There are few reasons why an intake manifold would need to be replaced. Obviously, if the manifold is cracked or the sealing surfaces are severely damaged, it should be replaced. The sealing surfaces should also be checked for flatness with a straightedge and feeler gauge. Minor imperfections on the surface can be filed away; however, do not attempt to clean up any serious damage.

The intake manifold distributes clear air to each cylinder of the engine.

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Another common problem is a leaking intake manifold gasket. This will create a vacuum leak that can cause stalling, rough running, misfire, and detonation from a lean air-fuel mixture. The intake manifold gasket can also allow coolant or oil leaks. You will need to remove the intake manifold and inspect the sealing surfaces to replace the intake manifold gasket. SERVICE TIP  The throttle body, fuel rail, and fuel injectors may need to be removed as an assembly when removing the intake manifold. The metal shield around the exhaust manifold from which a heated air inlet system picks up hot air may be called a heat stove.

The following is a typical intake manifold removal procedure:

The metal shield around the exhaust manifold from which a heated air inlet ­system picks up hot air may be called a heat stove.

1. Connect a 12-volt power supply recommended by the vehicle manufacturer to the cigarette lighter socket, and disconnect the negative battery cable. If the vehicle is air-bag-equipped, wait for the time period specified by the vehicle manufacturer before working on the vehicle. 2. Remove the sight cover bolts and the sight cover (Figure 7-12), and remove the duct between the air cleaner and the throttle body. 3. Open the large electrical harness retainer and then remove the retainer bolt, to separate the engine wiring harness from the intake manifold (Figure 7-13). 4. Disconnect the following electrical connectors: a. Eight fuel injector connectors b. Idle air control motor connector c. Throttle position sensor (TPS) connector d. Evaporative emission canister purge solenoid connector e. Manifold absolute pressure (MAP) sensor connector

Figure 7-12  Remove the sight cover from the intake manifold.

Figure 7-13  Remove the engine wiring harness retainer.

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Intake and Exhaust System Diagnosis and Service Retainer Vacuum line

307

Quick disconnect fittings are fuel line fittings that are removable with a special tool rather than threaded fittings.

Caution Fitting

Figure 7-14  Remove the purge solenoid vent hose.

Position the electrical connectors so they do not interfere with the intake manifold removal. 5. Squeeze the purge solenoid vent tube retainer, and pull the tube from the solenoid (Figure 7-14). Remove the inlet coolant hose from the throttle body. WARNING  Never disconnect any coolant hose or loosen the cooling ­system pressure cap if the engine coolant is warm or hot. The sudden decrease in cooling system pressure may cause the coolant to boil, resulting in personal injury.

6. Connect a fuel pressure gauge to the Schrader valve on the fuel rail, and place the gauge fuel drain hose in an approved gasoline container. Press the pressure relief valve on the gauge to relieve the fuel pressure. 7. Remove the dust covers from the quick disconnect fuel pipe fittings. Disconnect the quick disconnect fittings on the fuel supply and return lines. Use an air gun and shop air to blow any dirt from the quick disconnect fittings (Figure 7-15). Use a special tool on the quick disconnect fitting, and pull the connector apart (Figure 7-16). 8. Disconnect the vacuum brake booster hose from the intake manifold. 9. Remove the PCV valve and hose (Figure 7-17). 10. Remove the accelerator control cable bracket and retaining bolt, and disconnect the accelerator cable. If the vehicle is equipped with cruise control, disconnect the cruise control cable. 11. Remove the intake manifold retaining bolts, and remove the intake manifold and gaskets (Figure 7-18).

Quick disconnect fitting

Figure 7-15  Fuel lines with quick disconnect fittings.

Never reuse old intake manifold gaskets. This action may cause vacuum leaks and drivability problems.

Caution If any dirt particles or foreign objects enter the intake manifold or cylinder head air intake passages, they will likely be pulled into the combustion chambers when the engine is started, resulting in severe engine damage. Changing supercharger pulley size alters the supercharger rpm in relation to engine rpm, and this may cause improper boost pressure and engine performance problems.

Figure 7-16  The special quick disconnect fitting tools slide over the fitting to depress the locking tabs and allow the line to pull a part.

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PCV valve

Figure 7-17  Remove the PCV valve and hose.

Figure 7-18  Remove the intake manifold.

Inspect the intake manifold and cylinder head mating surfaces for nicks, scratches, cracks, and damage. Minor scratches may be polished out with crocus cloth. Always plug the cylinder head and intake manifold intake air passages with clean shop towels when the intake manifold is removed, to prevent any dirt particles or other objects from entering these passages. Clean the mating surfaces on the intake manifold and cylinder heads with a plastic scraper. Refer to Photo Sequence 15 for step-by-step pictures for removing and replacing an intake manifold gasket on a typical V6 engine.

PHOTO SEQUENCE 15

Typical Procedure for Removing and Replacing an Intake Manifold Gasket Smoke introduced into intake Smoke leaking from intake manifold gasket P15-1  A smoke leak detector reveals leakage from the intake manifold gasket.

P15-2  This manifold looks fairly simple to remove, but check the service information for tips and torque specifications and sequence.

P15-3  Disconnect the necessary vacuum lines and electrical connectors.

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PHOTO SEQUENCE 15 (CONTINUED)

EGR valve P15-4  This EGR valve needs to be unbolted from the manifold.

P15-5  Disconnect the throttle linkage.

P15-6  Remove the intake ducting.

P15-7  Loosen the intake manifold bolts in the opposite of the tightening sequence.

P15-8  Carefully lift the intake manifold off of the engine.

P15-9  Thoroughly clean the sealing surfaces, and install the new gaskets securely. These are installed dry.

P15-10  Place the intake manifold back into position without disturbing the gaskets.

P15-11  Torque the intake manifold in the ­correct sequence to the proper specification.

P15-12  Reconnect the intake ducting, throttle cable, EGR valve, and vacuum lines.

P15-13  Double-check your work to be sure you have reconnected all the electrical connectors and vacuum lines properly. Start the engine, listen for a smooth idle, and check for adequate vacuum. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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10

4

1

5

8

7

6

2

3

9

Throttle body

Figure 7-19  Tighten the intake manifold using the proper tightening sequence.

If the cylinder head or intake manifold mating surfaces are cracked or damaged, replace the necessary component(s). Inspect the intake manifold surface for cracks. Follow these steps to install the intake manifold:

Charging the ­supercharger pulley size alters the ­supercharger rpm in relation to engine rpm, and this may cause improper boost pressure and engine performance problems.

Caution Never reuse old intake manifold gaskets. This action may cause vacuum leaks and drivability problems. Classroom Manual Chapter 7, page 147

1. Install new intake manifold gaskets on the intake manifold. 2. Place a 0.20-inch (5-mm) band of threadlock GM part no. 12345382 or equivalent to the threads on the intake manifold bolts. 3. Install the intake manifold and the retaining bolts. Start each bolt into its threaded opening by hand, and then tighten each bolt to the specified torque in the sequence in Figure 7-19. 4. Install the PCV valve and hose. 5. Install the accelerator cable, bracket, and retaining bolt. Tighten this bolt to the specified torque. 6. Install the cruise control cable if equipped. 7. Install the vacuum brake booster hose. 8. Place a few drops of the appropriate lube on the male ends of the fuel supply and return pipes. Push the quick disconnect fitting together. After these fittings are pushed together, pull on both sides of the quick disconnect fitting to be sure the fitting does not pull apart. Install the dust covers over the quick disconnect fittings. 9. Install the purge solenoid vent tube. 10. Disconnect the fuel pressure gauge from the Schrader valve on the fuel rail. 11. Connect all the electrical connectors to sensors and components mounted on the intake manifold. 12. Install the engine wiring harness retainer attaching bolt, and install this harness in the retainer. 13. Install the sight cover and bolts. 14. Reconnect the negative battery cable, and disconnect the 12-volt power supply from the cigarette lighter socket. 15. Start the engine, and be sure engine operation and idle speed are normal. 16. Use a vacuum gauge, smoke machine, or scan tool to verify your work has been completed and the engine works fine before you close the hood. 17. Test-drive the vehicle to make sure the customer complaint was repaired.

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Intake and Exhaust System Diagnosis and Service

CUSTOMER CARE  Never sell customers automotive service that is not required on their cars. Selling preventive maintenance is a sound business practice and may save customers some future problems. An example of preventive maintenance is selling a cooling system flush when the cooling system is not leaking but the manufacturer’s recommended service interval has elapsed. If customers find out they were sold some unnecessary service, and some will find out, they will probably never return to the shop. They will likely tell their friends about their experience, and that kind of advertising the shop can do without.

EXHAUST SYSTEM SERVICE Exhaust system components are subject to both physical and chemical damage. Any physical damage to an exhaust system part that causes a partially restricted or blocked exhaust system usually results in loss of power or backfire up through the throttle plate(s). In addition to improper engine operation, a blocked or restricted exhaust system causes increased noise and air pollution.

Exhaust System Inspection Most parts of the exhaust system, particularly the front pipe, muffler, and tailpipe, are subject to rust, corrosion, and cracking. Broken or loose clamps and hangers can allow parts to separate or hit the road as the car moves. Some newer diesel engines use a different type of exhaust system that is essential to its emissions system. This is known as an after-treatment system. This type of exhaust uses a diesel particulate filter that captures soot to incinerate it during regeneration cycles. The engine computer uses a strategy to spray a fine mist of diesel exhaust fluid (DEF) in the exhaust during certain periods. This helps clean up the exhaust emissions and burn the soot in the filter. This reduces the black smoke typically found in the exhaust of a diesel engine. WARNING If the engine has been running, exhaust system components may be extremely hot! Wear protective gloves when working on these components, and keep flammable objects away from hot areas. WARNING  Exhaust gas contains poisonous carbon monoxide (CO) gas. This gas can cause illness and death by asphyxiation. Exhaust system leaks are dangerous for customers and technicians.

Any exhaust system inspection should include listening for hissing or rumbling that would result from a leak in the system. An on-lift inspection should pinpoint any of the following types of damage:

311

Caution Leaks in the exhaust system can result in illness, asphyxiation, or even death. Remember that vehicle exhaust fumes can be very dangerous to one’s health. The front pipe connects the exhaust manifolds to the catalytic converter or muffler. The muffler is a device mounted to the exhaust system behind the catalytic converter that reduces engine noise. The tailpipe conducts exhaust gases from the muffler to the rear of the vehicle. Diesel particulate filters trap soot (also known as particulate matter) and are located in the exhaust system. Diesel exhaust fluid (DEF) is a fluid that is added to some diesel vehicles. This fluid is sprayed into the exhaust under certain operating conditions.

1. Holes, road damage, separated connections, and bulging muffler seams 2. Kinks and dents 3. Discoloration, rust, soft corroded metal, and so forth 4. Torn, broken, or missing hangers and clamps 5. Loose tailpipes or other components 6. Bluish or brownish catalytic converter shell, which indicates overheating

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Muffler cutter

Expander

Sealant

Air chisel

Chain pipe cutter

Shaper

Pipe cutter

Hanger removal tool

Figure 7-20  Exhaust system service tools.

Replacing Exhaust System Components Before beginning work on an exhaust system, make sure it is cool to the touch. Some technicians disconnect the battery’s negative cable before starting to work to avoid shortcircuiting the electrical system. Soak all rusted bolts, nuts, and other removable parts with a good penetrating oil, and give plenty of time for the oil to sit on the bolts. Finally, check the system for critical clearance points, so they can be maintained when new components are installed. Most exhaust work involves the replacement of parts. When replacing exhaust parts, make sure the new parts are exact replacements for the original parts. Doing this will ensure proper fit and alignment, as well as ensure acceptable noise levels. Exhaust system component replacement might require the use of special tools (Figure 7-20). Many technicians will use oxyacetylene torches to heat or cut exhaust connections and components. With practice, it is possible to cut a leaky pipe off of a good one without damaging the good pipe. This process is often faster than trying to use an air chisel or muffler cutter to remove a bad pipe. You can also use torches to apply heat. Heating the outer pipe of a connection will usually cause the metal to expand enough to allow you to pull the pipes apart. Similarly, heating rusty nuts in the exhaust system will greatly help removal.

Exhaust Manifold and Exhaust Pipe Servicing As mentioned, the manifold itself rarely causes any problems. On occasion, an exhaust manifold will warp because of excess heat. A straightedge and feeler gauge can be used to check the machined surface of the manifold. Another problem, also the result of high temperatures generated by the engine, is a cracked manifold. This usually occurs after the car passes through a large puddle and coldwater splashes on the manifold’s hot surface. If the manifold is warped beyond manufacturer’s specifications or is cracked, it must be replaced. Also, check the exhaust pipe for signs of collapse. If there is damage, repair it. These repairs should be done as directed in the vehicle’s service manual.

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SERVICE TIP  If a heated oxygen sensor(HO2S) is mounted in the exhaust manifold, a cracked manifold upstream from the HO2S allows air to enter the exhaust manifold. This air affects the HO2S sensor signal and causes the ­powertrain control module (PCM) to supply a rich air-fuel ratio.

Replacing Exhaust System Gaskets and Seals The most likely spot to find leaking gaskets and seals is between the exhaust manifold and the front pipe (Figure 7-21). When installing exhaust gaskets, carefully follow the recommendations on the gasket package label and instruction forms. Read through all installation steps before beginning. Take note of any of the original equipment manufacturer’s recommendations in service manuals that could affect engine sealing. Manifolds warp more easily if an attempt is made to remove them while they are still hot. Remember, heat expands metal, making assembly bolts more difficult to remove and easier to break. To replace an exhaust manifold gasket, follow the torque sequence in reverse to loosen each bolt. Repeat the process to remove the bolts. This minimizes the chance that components will warp. Some exhaust manifolds have precision “machined” surfaces and do not come with a gasket from the factory. In some cases aftermarket and factory gaskets are available for these. Exhaust manifold studs and nuts are often very rusty due to the high heat they are subjected to (Figure 7-22). Heat the nuts to prevent breaking the studs off in the cylinder head. Any debris left on the sealing surfaces increases the chance of leaks. A gasket remover solvent applied to the old gasket will quickly soften it and the old adhesive for quick removal with a hand scraper. Carefully remove the softened pieces with a scraper and

CAUTION Be sure no part of the exhaust system contacts any part of the chassis, fuel lines, fuel tank, or brake lines. This condition causes a rattling noise and/ or damage to other components.

Stud Spring

Exhaust manifold Gasket

Nut Front pipe

Figure 7-21  Front pipe to manifold gasket.

Figure 7-22  It will be necessary to heat these rusty nuts before trying to loosen them, to avoid breaking the studs off in the cylinder head.

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Special Tools Splitting tool

Special Tools Digital pyrometer

a wire brush. Be sure to use a nonmetallic scraper when attempting to remove gasket ­material from aluminum surfaces. Inspect the manifold for irregularities that might cause leaks, such as gouges, scratches, or cracks. Replace it if it is cracked or badly warped. You can use a feeler gauge set and a straightedge to check for warpage. File down any imperfections to ensure proper sealing of the manifold. Due to high heat conditions, it is important to retap and redie all threaded bolt holes, studs, and mounting bolts. This procedure ensures tight, balanced clamping forces on the gasket. Lubricate the threads with a good high temperature antiseize lubricant. Most gaskets should be installed dry. If needed, a small amount of contact adhesive can be used to hold paper, cork, or some rubber gaskets in place. Align the gasket properly before the adhesive dries. Allow the adhesive to dry completely before proceeding with manifold installation. Install the bolts finger-tight. Tighten the bolts in three steps, one-half, three-quarters, and full torque, following the torque tables in the service manual or gasket manufacturer’s instructions. Torquing is usually begun in the center of the manifold, working outward in an X pattern. To replace a damaged front pipe, begin by supporting the converter to keep it from falling. Carefully remove the oxygen sensor if there is one. Remove any hangers or clamps holding the exhaust pipe to the frame. Unbolt the flange holding the exhaust pipe to the exhaust manifold. When removing the exhaust pipe, check to see if there is a gasket. If so, discard it and replace it with a new one. Once the joint has been taken apart, the gasket loses its effectiveness. Disconnect the pipe from the converter, and pull the front exhaust pipe loose and remove it. Although most exhaust systems use flanges or a slip joint and clamps to fasten the pipe to the muffler, a few use a welded connection. If the vehicle’s system is welded, cut  the pipe at the joint with a hacksaw or pipe cutter. The new pipe need not be welded to the muffler. An adapter, available with the pipe, can be used instead. When measuring the length for the new pipe, allow at least 2 inches (50.8 mm) for the adapter to enter the muffler. WARNING  Wear safety goggles to protect your eyes and work gloves to ­protect your hands from burns and cuts.

When trying to replace a part in the exhaust system, you may run into parts that are rusted together. This is especially a problem when a pipe slips into another pipe or the muffler. If you are trying to reuse one of the parts, you should carefully use a cold chisel or splitting tool (Figure 7-23) on the outer pipe of the rusted union. You must be careful when doing this, because you can easily damage the inner pipe. It must be perfectly round to form a seal with a new pipe. Slide the new pipe over the old. Position the rest of the exhaust system so that all clearances are evident and the parts aligned, then put a U-clamp over the new outer pipe to secure the connection (Figure 7-24).

Catalytic Converter Testing A catalytic converter reduces tailpipe emissions of carbon monoxide, unburned hydrocarbons, and nitrogen oxides.

The shell of a catalytic converter can become damaged like any other part of the exhaust system and require replacement (Figure 7-25). The converter can also be damaged internally and fail to perform as designed. A converter can fail to reduce emissions adequately. On an OBD II vehicle, the malfunction indicator light (MIL) will illuminate and a diagnostic trouble code (DTC) will be stored if the catalytic converter is not functioning properly. If the MIL is flashing during engine operation, it is a warning that if the vehicle

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Outer pipe

Inner pipe

Splitting tool

Ball peen hammer

Figure 7-23  Using an exhaust pipe splitting tool.

Figure 7-24  Install the new pipe, and secure it with a U-clamp.

Figure 7-25  A catalytic converter.

continues to operate in that condition, catalytic converter damage may occur. A flashing MIL, usually caused by a severe misfire, will set a DTC or continuing of misfires. The DTC will usually be P0420, low catalyst efficiency. The on-board diagnostic (OBD) system checks the efficiency of the catalytic converter by comparing the signals from the pre- and post-catalytic converter oxygen sensors. When the OBD system has determined that the catalyst is no longer at least 60 percent efficient, it must be replaced. On an older vehicle, you can also test if the catalytic converter is functioning by using a digital pyrometer. Be sure the vehicle is thoroughly warmed up before testing. Measure the temperature of the pipe going into the converter and the temperature of the pipe ­coming out. The outlet pipe should be at least 1008F (37.78C) hotter than the inlet pipe if the converter is working. If the outlet temperature is the same or lower, nothing is happening inside the converter.

A digital pyrometer is an electronic device that measures heat.

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Restricted exhaust is an exhaust system that offers more-thannormal restriction to the exhaust flow.

Before purchasing a new catalytic converter, check with the manufacturer for a warranty. Catalytic converters are covered by the emission control components of federal law. They are covered for 8 years/80,000 miles. New aftermarket converters must have a 5-year/50,000-mile warranty on the shell, casing, and end pipes, and a 25,000-mile warranty on the substrate and inside components.

A common source of drivability problems related to the catalytic converter is a restricted exhaust. The catalytic converter can often become partially or fully plugged, particularly after it has been overheated by extended periods of misfire or rich running. When this happens, the engine will lose power. It will accelerate slowly and have a hard time reaching higher speeds. In severe cases, the engine may stall or fail to start. If you suspect a restricted exhaust, give a light tap to the converter and to the muffler. Rattling in either component indicates internal damage that may be causing a restriction. There are several ways to test for a restricted exhaust. One way is to use the vacuum test we discussed previously. Place a vacuum gauge on an intake manifold vacuum port, and watch the gauge while you rev the engine to 2,500 rpm. Hold the rpm up for a couple of minutes, and monitor the gauge. If the vacuum falls, the exhaust is restricted. The vacuum falls because the high volume of air trying to pass through the exhaust starts to back up in the system and leaves residual pressure in the cylinder on the intake stroke. This reduces engine vacuum and power. You can also use a backpressure gauge to test the exhaust system (Figure 7-26). Install the gauge into the exhaust ahead of the converter. The gauge will typically read from 0 psi to 10 psi in half-psi increments. Often the gauge has an adapter that screws into the front oxygen sensor port. Other setups may require that you drill or punch a small hole in the front exhaust pipe and screw the gauge in. Always seal that hole before returning the vehicle to the customer. With the gauge installed, check the pressure at idle, 2,500 rpm, and under a hard, quick snap of the throttle. The pressure at idle should be near 0 psi, and it should stay below 1.5 psi at 2,500 rpm. During a snap of the throttle, the pressure should not exceed 4 psi. If the pressure is too high, remove the converter, and inspect it for damage. It is more common for a converter to fail than a muffler, but you may also have to remove and check the muffler or mufflers. Always consult the service manual for specific testing procedures on each vehicle. A converter is expensive, so be sure that replacing it will fix the problem! After replacing the catalytic converter, you should carefully verify that the engine is running properly. Most converters fail due to overheating from burning excess fuel. An ignition misfire or an excessively rich mixture can damage a catalytic converter in a relatively short time. Be sure that you cure the cause of the problem, to prevent the vehicle from returning with another damaged converter.

Figure 7-26  An exhaust pressure gauge.

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TURBOCHARGER DIAGNOSIS A faulty turbocharger can cause a serious lack of power. If the turbocharger fails to ­produce adequate boost pressure, the engine will be sluggish on acceleration. The turbo-charger itself could be faulty, but there are other possible causes of low boost pressure. The whole system must be inspected to correctly diagnose the cause. Other symptoms caused by problems with the turbocharging system include the following:

1. Whining on acceleration from worn turbocharger bearings 2. Blue smoke from worn turbocharger seals 3. Misfire and hesitation on acceleration from a leak in the intake ductwork 4. Engine detonation or overheating from overboosting

WARNING  If the engine has been running, turbochargers and related components will be extremely hot. Use caution and wear protective gloves to avoid burns when servicing these components.

The first step in turbocharger diagnosis is to check all linkages and hoses connected to the turbocharger (Figure 7-27). Inspect the wastegate diaphragm linkage for looseness and binding, and check the hose from the wastegate diaphragm to the boost control solenoid for cracks, kinks, and restrictions. Also, check the coolant hoses and oil line connected to the turbocharger for leaks. Excessive blue smoke in the exhaust may indicate worn turbocharger seals. The technician must remember that worn valve guide seals or piston rings also cause oil consumption and blue smoke in the exhaust. When oil leakage is noted at the turbine end of the turbocharger, always check the oil drain tube and engine crankcase breathers for restrictions. If sludge is found in the crankcase, change the oil and filter after flushing clean the engine, Check all turbocharger mounting bolts for looseness. A rattling noise may be caused by loose turbocharger mounting bolts. Some whirring noise is normal when the turbocharger shaft is spinning at high speed. Excessive internal turbocharger noise may be caused by too much shaft end play, which allows the blades to strike the housings. Turbine housing

A turbocharger is a device that is driven by exhaust pressure and that forces air into the cylinders.

Oil inlet Compressor housing

Wastegate linkage

Hose to boost control solenoid

Oil drain

Figure 7-27  Typical turbocharger assembly.

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Check for exhaust leaks in the turbine housing and related pipe connections. If exhaust gas is escaping before it reaches the turbine wheel, turbocharger effectiveness is reduced. Check for intake system leaks. If there is a leak in the intake system before the compressor housing, dirt may enter the turbocharger and damage the compressor or turbine wheel blades. When a leak is present in the intake system between the compressor wheel housing and the cylinders, turbocharger pressure is reduced. If the turbocharger’s boost is controlled by the engine computer, a DTC is stored in the PCM memory if a fault is present in the boost control solenoid or solenoid-to-PCM wiring. The following is a guide for turbocharger diagnosis and service: 1. A basic turbocharger inspection involves inspecting all turbocharger linkages, hoses, and lines, and checking for intake system and exhaust leaks. 2. Leaks in the air intake system may allow dirt particles to enter the turbocharger and damage the blades. 3. Exhaust leaks between the cylinders and the turbocharger decrease turbocharger efficiency. 4. Blue smoke in the exhaust may be caused by worn turbocharger seals, worn valve stem seals and guides, or worn piston rings. 5. Low cylinder compression reduces airflow through the engine and decreases turbocharger shaft speed and boost pressure. 6. Higher-than-specified boost pressure may be caused by a defective wastegate system. Higher-than-specified boost pressure may also be caused by the installation of after-market components or aftermarket computer reprogramming. 7. Lower-than-specified boost pressure may be caused by a faulty wastegate system, worn turbocharger bearings or blades, or low cylinder compression. 8. When the axial movement on the turbocharger shaft is more than specified, the blades may strike the end housings. 9. Premature turbocharger bearing failure may be caused by lack of lubrication, contaminated oil, or a contaminated cooling system. 10. After the turbocharger has been replaced, it must be prelubricated before starting the engine. 11. It should be explained to the customer that to prolong turbocharger life the engine should be allowed to idle for a minute or two before shut down. SERVICE TIP  If the engine has low cylinder compression, there is reduced airflow through the cylinders, which results in lower turbocharger shaft speed and boost pressure.

SERVICE TIP  Excessive boost pressure causes engine detonation and ­possible engine damage.

Common Turbocharger Failures The turbocharger is designed to provide years of useful service. Most premature failures of the turbocharger are due to lack of lubrication, contamination of the lubricant, or ingestion of foreign objects. Figure 7-28 provides information concerning troubleshooting the turbocharger and recommended remedies. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Intake and Exhaust System Diagnosis and Service

Condition

Possible Causes Code Numbers

Remedy Description by Code Numbers

Engine lacks power

1, 4, 5, 6, 7, 8, 9, 10, 11, 18, 20, 21, 22, 25, 26, 27, 28, 29, 30, 37, 38, 39, 40, 41, 42, 43

Black smoke

1, 4, 5, 6, 7, 8, 9, 10, 11, 18, 20, 21, 22, 25, 26, 27, 28, 29, 30, 37, 38, 39, 40, 41, 43

Blue smoke

1, 2, 4, 6, 8, 9, 17, 19, 20, 21, 22, 32, 33, 34, 37, 45

Excessive oil consumption

2, 8, 15, 17, 19, 20, 29, 30, 31, 33 34, 37, 45

Excessive oil turbine end

2, 7, 8, 17, 19, 20, 22, 29, 30, 32, 33, 34, 45

Excessive oil compressor end

1, 2, 4, 5, 6, 8, 19, 20, 21, 29, 30, 33, 34, 45

Insufficient lubrication

8, 12, 14, 15, 16, 23, 24, 31, 34, 35, 36, 44, 46

Oil in exhaust manifold

2, 7, 17, 18, 19, 20, 22, 29, 30, 33, 34, 45

Damaged compressor wheel

3, 4, 6, 8, 12, 15, 16, 20, 21, 23, 24, 31, 34, 35, 36, 44, 46

Damaged turbine wheel

7, 8, 12, 13, 14, 15, 16, 18, 20, 22, 23, 24, 25, 28, 30, 31, 34, 35, 36, 44, 46

Drag or bind in rotating assembly

3, 6, 7, 8, 12, 13, 14, 15, 16, 18, 20, 21, 22, 23, 24, 31, 34, 35, 36, 44, 46

Worn bearings, journals, bearing bores

6, 7, 8, 12, 13, 14, 15, 16, 23, 24, 31, 35, 36, 44, 46

Noisy

1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, 21, 22, 23, 24, 31, 34, 35, 36, 37, 44, 46

Sludged or coked center housing

2, 11, 13, 14, 15, 17, 18, 24, 31, 35, 36, 44, 46

1. Dirty air cleaner element 2. Plugged crackcase breathers 3. Air cleaner element missing, leaking, not sealing correctly; loose connections to turbocharger 4. Collapsed or restricted air tube before turbocharger 5. Restricted-damaged crossover pipe, turmocharger to inlet manifold 6. Foreign object between air cleaner and turbocharger 7. Foreign object in exhaust systme (from engine, check engine) 8. Turbocharger flanges, clamps, or bolts loose 9. Inlet manifold cracked; gaskets loose or missing, connections loose 10. Exhaust manifold cracked, burned; gaskets loose, blown, or missing 11. Restricted exhaust system 12. Oil lag (oil delay to turbocharger at startup) 13. Insufficient lubrication 14. Lubricating oil contaminated with dirt or other material 15. Improper type lubricating oil used 16. Restricted oil feed line 17. Restricted oil drain line 18. Turbine housing damaged or restricted 19. Turbocharger seal leakage 20. Worn journal bearings 21. Excessive dirt buildup in compressor housing 22. Excessive carbon buildup behind turbine wheel 23. Too fast acceleration at initial start (oil lag) 24. Too little warm-up time 25. Fuel pump malfunction 26. Worn or damaged injectors 27. Valve timing 28. Burned valves 29. Worn piston rings 30. Burned pistons 30. Burned pistons 31. Leaking oil feed line 32. Excessive engine pre-oil 33. Excessive engine idle 34. Coked or sludged center housing 35. Oil pump malfunction 36. Oil filter plugged 37. Oil-bath-type air cleaner: ◆ Air inlet screen restricted ◆ Oil pullover ◆ Dirty air cleaner ◆ Oil viscosity low ◆ Oil viscosity high 38. Actuator damaged or defective 39. Wastegate binding 40. Electronic control module or connector(s) defective 41. Wastegate actuator solenoid or connector defective 42. EGR valve defective 43. Alternator voltage incorrect 44. Engine shut off without adequate cool-dowm time 45. Leaking valve guide seals 46. Low oil level

Figure 7-28  Turbocharger troubleshooting guide.

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Turbocharger Inspection To inspect the turbocharger, start the engine and listen for noises being generated within the turbocharger. A high-pitched sound may indicate an air leak between the compressor wheel and the intake manifold. If the sound changes in intensity, the likely causes are a plugged air filter element, loose material in the inlet ducts, or dirt buildup on the wheels and housing. Check for loose clamps on all ducting associated with the turbocharger system (including the intercooler). Visually inspect all hoses, gaskets, and tubing for proper fit, damage, and wear. If there is no problem found in this area, remove the air cleaner and the ducting from the air cleaner to the turbo. Look for dirt buildup and damage from foreign objects. Once the turbocharger has fully cooled, inspect the wheels for free rotation. Also, look into the housing and visually inspect for signs of wheel-to-housing interference. Check the end of the turbine shaft to see if it is loose. The high-pressure side of the turbocharger system can be checked for leaks with the use of soapy water. While applying the solution to the connections, tubing, and the intercooler, watch for the presence of bubbles to pinpoint the leak. Leakage or restrictions in the exhaust system above the turbine housing will reduce turbocharger efficiency. Also, check for free operation of the wastegate ­actuator. Be sure to check the hose that is attached to the actuator for damage. Photo Sequence 16 shows a typical procedure for inspecting turbochargers and testing boost pressure.

Testing Boost Pressure Boost pressure is the amount of pressure supplied by the turbocharger to the intake manifold.

Low turbocharger boost pressure causes reduced engine performance. A wastegate is a valve that opens to bypass some exhaust around the turbine wheel to limit turbocharger boost pressure.

To test boost pressure, begin by connecting a pressure gauge to the intake manifold. The pressure gauge hose should be long enough so the gauge may be positioned in the passenger compartment. Road test the vehicle at the speed specified by the vehicle manufacturer, and observe the boost pressure. Some vehicle manufacturers recommend accelerating from a stop to 60 mph (96 km/h) at wide-open throttle while observing the boost pressure. Higher-than-specified boost pressure may be caused by a defective wastegate system. Low boost pressure may be caused by the wastegate system or turbocharger defects such as damaged wheel blades or worn bearings. An engine with low cylinder compression will usually have low boost pressure. Wastegate malfunctions can often be traced to carbon buildup that prevents bypass valve closing or causes it to bind. Also, check the linkage for bends that would prevent free movement. Usually, adjustment of the actuator rod is not necessary (unless someone misadjusted it previously). To test the wastegate on a PCM-controlled system, install a vacuum pump on the inlet hose. Pull a vacuum while monitoring the wastegate actuator rod. It should move freely and hold the wastegate open while vacuum is applied. If it fails to move, be sure that the linkage is not seized. If the linkage moves freely, replace the faulty wastegate. On an older system that relies on boost pressure to operate the wastegate, you’ll apply pressure to verify wastegate operation. Locate the pressure at which the wastegate is supposed to open. Apply that pressure to the wastegate hose to check actuator rod movement.

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PHOTO SEQUENCE 16

Typical Procedure for Inspecting Turbochargers and Testing Boost Pressure

P16-1  Check all turbocharger linkages for looseness, and check all turbocharger hoses for leaks cracks, kinks, and restrictions.

P16-2  Check the level and condition of the engine oil on the dipstick.

P16-3  Check the exhaust for evidence of blue smoke when the engine is accelerated.

P16-4  Check all turbocharger mounting bolts for looseness.

P16-5  Check for exhaust leaks between the engine and turbocharger, and use a stethoscope to listen for excessive turbocharger noise.

P16-6  Use a propane cylinder, metering valve, and hose to check for intake manifold vacuum leaks.

P16-7  Connect a pressure gauge to the intake manifold, and locate the gauge in the passenger compartment where it can be seen easily by the driver.

P16-8  Road-test the car and accelerate from 0 to 60 mph at wide-open throttle while observing the pressure gauge.

P16-19  Disconnect the pressure gauge from the intake manifold, and remove the gauge from the passenger compartment.

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On a PCM-controlled turbocharging system, be sure that there are no DTCs and that the fuel and ignition systems are functioning properly. A fault in the intake air temperature sensor, for example, could cause the PCM to limit boost pressure. Repair all related malfunctions before condemning the turbocharger.

Turbocharger Removal The turbocharger removal procedure varies depending on the engine; for example, on some cars, such as a Nissan 300 ZX, the manufacturer recommends the engine be removed to gain access to the turbocharger. On other applications, the turbocharger may be removed with the engine in the vehicle. Always follow the turbocharger removal procedure in the vehicle manufacturer’s service manual. The following is a typical turbocharger removal procedure:

Special Tools Pressure gauge Hand pressure pump Dial indicator

1. Disconnect the negative battery cable, and drain the cooling system. 2. Disconnect the exhaust pipe from the turbocharger. 3. Remove the support bracket between the turbocharger and the engine block. 4. Remove the bolts from the oil drain back housing on the turbocharger. 5. Disconnect the turbocharger coolant inlet tube nut at the block outlet, and remove the tube-support bracket. 6. Remove the air cleaner element, air cleaner box, bracket, and related components. 7. Disconnect the accelerator linkage, throttle body electrical connector, and vacuum hoses. 8. Loosen the throttle-body-to-turbocharger inlet hose clamps, and remove the three throttle-body-to-intake manifold attaching screws. Remove the throttle body. 9. Loosen the lower turbocharger discharge hose clamp on the compressor wheel housing. 10. Remove the fuel-rail-to-intake-manifold screws and the fuel line bracket screw. Remove the two fuel-rail-bracket-to-heat-shield-retaining clips, and pull the fuel rail and injectors upward out of the way. Tie the fuel rail in this position with a piece of wire. 11. Disconnect the oil supply line from the turbocharger housing. 12. Remove the intake manifold heat shield. 13. Disconnect the coolant return line from the turbocharger and the water box. Remove the line-support bracket from the cylinder head and remove the line. 14. Remove the four nuts retaining the turbocharger to the exhaust manifold, and remove the turbocharger from the manifold studs. Move the turbocharger downward toward the passenger side of the vehicle, and then lift the unit up and out of the engine compartment. CUSTOMER CARE  When returning vehicles to customers after a turbocharger replacement, be sure to discuss proper care and maintenance with them. Remind them that they should allow the turbo to wind down before shutting the vehicle off. This simply means that they should let the engine idle for a minute after driving before turning the ignition off. You should also remind them that regular oil changes are essential to turbocharger life. They can help ensure that the customer won’t be back anytime soon for turbocharger service.

Turbocharger Component Inspection If the vehicle manufacturer recommends turbocharger disassembly, inspect the wheels and shaft after the end housings are removed. Lack of lubricant or lubrication with contaminated oil results in bearing failure, which leads to wheel rub on the end housings. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Burnt bearings

Damaged blades Scored shaft

Figure 7-29  Inspect the turbocharger components for damage.

End housing

Figure 7-30  Inspect the end housing for wear.

A contaminated cooling system may provide reduced turbocharger bearing cooling and premature bearing failure. Bearing failure will likely lead to seal damage. Inspect the shaft and bearings for a burned condition (Figure 7-29). If the shaft and bearings are burned, replace the complete center housing assembly or individual parts as recommended by the manufacturer. If the shaft and bearings are in satisfactory condition, but the blades are damaged, check the air intake system for leaks or a faulty air cleaner element. When the blades or shaft and bearings must be replaced, always check the end housings for damage (Figure 7-30). When these housings are marked or scored, replacement is necessary. Since turbocharger components are subjected to extreme heat, use a straightedge to check all mating surfaces for a warped condition. Replace warped components as necessary.

Turbocharger Installation and Prelubrication Prior to reinstalling the turbocharger, be sure the engine oil and filter are in satisfactory condition. Change the oil and filter as required, and be sure the proper oil level is indicated on the dipstick. Check the coolant for contamination. Flush the cooling system if contamination is present. Reverse the turbocharger removal procedure explained previously Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 7 Plug (drain/fill)

Thermostat housing

Water box

Coolant temperature sensor

Figure 7-32  Prelubricate the turbocharger bearings by pouring oil in the oil inlet.

Figure 7-31  Remove the plug at the top of the water box while ­filling the cooling system.

CAUTION Failure to prelubricate turbocharger bearings may result in premature bearing failure.

Prelubrication entails lubricating turbocharger bearings or other components before starting the engine.

to install the turbocharger. Replace all gaskets, and be sure all fasteners are tightened to the specified torque. Before installing the new turbocharger, carefully check the oil supply and return lines for restrictions. If there is any sludge buildup in the hoses, clean them thoroughly or replace them. Restricted oil lines can cause premature failure of the new turbocharger. Follow the vehicle manufacturer’s recommended procedure for filling the cooling system. On some DaimlerChrysler engines, this involves removing a plug on top of the water box and pouring coolant into the radiator filler neck until coolant runs out the hole in the top of the water box (Figure 7-31). Install the plug in the top of the water box, and tighten the plug to the specified torque. Continue filling the cooling system to the maximum-level mark on the reserve tank. The turbocharger bearings must be prelubricated before starting the engine to prevent bearing damage. Some vehicle manufacturers recommend removing the turbocharger oil supply pipe and pouring a half pint of the specified engine oil into the turbocharger to prelubricate the bearings (Figure 7-32). Other vehicle manufacturers recommend disabling the ignition system by disconnecting the positive primary coil wire and cranking the engine for 10 to 15 seconds to allow the engine lubrication system to lubricate the turbocharger bearings. Always follow the turbocharger prelubrication instructions in the vehicle manufacturer’s service manual.

SUPERCHARGER DIAGNOSIS AND SERVICE A supercharger is a belt-driven device that forces more air into the cylinders.

The supercharger is not subjected to high speeds and temperatures like the turbocharger; however, it does operate at a high speed with very close tolerances. Proper lubrication is essential for long supercharger life. The fluid in the front supercharger housing lubricates the rotor drive gears. This fluid does not require changing for the life of the vehicle; however, this fluid level should be

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checked at 30,000-mile (48,000 km) intervals. To check the fluid level in the front supercharger housing, remove the Allen head plug in the top of this housing. The fluid should be level with the bottom of the threads in the plug opening. If the fluid level is low, add the required amount of synthetic fluid that meets the vehicle manufacturer’s specifications.

Supercharger Diagnosis The supercharger on most vehicles is serviced as an assembly only. Specialty shops with proper equipment may rebuild some superchargers if parts are available. Therefore, the technician must diagnose supercharger problems and replace the supercharger only if necessary. Supercharger problems include low boost, high boost, reduced vehicle response and/or fuel economy, noise, and oil leaks.

Classroom Manual Chapter 7, page 156

Supercharger Removal Follow these steps for supercharger removal:

1. Disconnect the negative battery cable. 2. Remove the air inlet tube from the throttle body. 3. Remove the cowl vent screens. 4. Drain the coolant from the radiator. 5. Disconnect the spark plug wires from the spark plugs in the right cylinder head, and position them out of the way. 6. Remove the electrical connections from the air charge temperature sensor, throttle position sensor, and idle air control valve. 7. Disconnect the vacuum hoses from the supercharger air inlet plenum. 8. Remove the exhaust gas recirculation (EGR) transducer from the bracket, and disconnect the vacuum hose to this component. 9. Disconnect the positive crankcase ventilation (PCV) tube from the supercharger air inlet plenum. 10. Disconnect the throttle linkage, and remove the throttle linkage bracket. Position this linkage and bracket out of the way. Remove the cruise control linkage if equipped. 11. Remove the two EGR-valve-attaching bolts, and place this valve out of the way. 12. Remove the coolant hoses from the throttle body. 13. Remove the supercharger drive belt. 14. Remove the inlet and outlet tubes from the intercooler (Figure 7-33). 15. Remove three intercooler-adapter-attaching bolts from the intake manifold. 16. Remove three supercharger mounting bolts (Figure 7-34). 17. Remove the supercharger and air intake plenum as an assembly. Follow these steps to install the supercharger: 1. Clean all gasket surfaces, and inspect these surfaces for scratches and metal burrs. Remove metal burrs as required. 2. Place a new gasket on the intake manifold surface that mates with the supercharger intercooler adapter. 3. Install the supercharger, throttle body, and air intake plenum as an assembly. 4. Install three supercharger mounting bolts, and tighten these bolts to the specified torque. 5. Install three bolts that retain the intercooler adapter to the intake manifold, and tighten these bolts to the specified torque. 6. Install the intercooler inlet and outlet tubes, and tighten all mounting bolts to the specified torque. 7. Install the coolant hoses on the throttle body, and tighten these hose clamps.

A slipping drive belt is often the cause of low supercharger boost pressure.

A blown engine may refer to a supercharged engine. This term may also refer to an engine with ­serious mechanical problems.

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Chapter 7 Intercooler inlet tube assembly

Intercooler outlet tube

Intercooler

Supercharger

Figure 7-33  Intercooler inlet and outlet tubes.

Intake manifold adapter Supercharger

Air intake plenum

Figure 7-34  Supercharger mounting bolt location.

8. Install a new EGR valve gasket, and install the EGR valve. Tighten the EGR-valvemounting bolts to the specified torque. 9. Install the throttle linkage and bracket, and tighten the bracket bolts to the specified torque. 10. Connect all the vacuum hoses to the original locations on the air intake plenum, EGR valve, and EGR transducer. 11. Install the spark plug wires on the spark plugs in the right cylinder head, and connect the electrical connectors to the throttle position sensor, air charge temperature sensor, and idle air control valve. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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12. Install the cowl covers. 13. Install and tighten the air inlet tube on the throttle body. 14. Install the supercharger drive belt. 15. Refill the cooling system to the proper level. 16. Connect the battery ground cable. 17. Start the engine, and check for air leaks in the supercharger system.

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Some German ­manufacturers call a supercharger a ­compressor because it compresses the incoming air.

CASE STUDY A customer complained about loss of power and a top speed of 55 mph (88 km/h) on a 2000 Oldsmobile Intrigue with a 3.5L V6 engine. The technician road tested the car to verify the customer’s complaint. The car did have a maximum top speed of 55 mph (88 km/h), but the engine ran smoothly at idle speed. During the road test, the technician observed the malfunction indicator light (MIL) in the instrument panel. This light was not illuminated with the engine running, indicating there were no diagnostic trouble codes (DTCs) in the PCM. When the technician returned to the shop, he performed a visual under-hood and under-car inspection of the wiring harness, fuel lines, exhaust system, and vacuum system. The visual inspection did not reveal any damaged, loose, disconnected, or defective components. The technician tested the fuel pressure and flow and found these values were within specifications. Next the technician connected a vacuum gauge to the intake manifold. With the engine idling, the vacuum was a steady 18 in. Hg (60.8 kPa). When the technician held the engine at 2,500 rpm for 3 minutes, the vacuum slowly decreased to 12 in. Hg (40.6 kPa), indicating a restricted exhaust system. When the front exhaust pipe was disconnected, the technician discovered the inside wall of this double-walled pipe had collapsed and severely restricted the exhaust passage through the pipe. After replacing this exhaust pipe, normal vehicle operation was restored.

ASE-STYLE REVIEW QUESTIONS 1. Airflow restriction indicators are being discussed. Technician A says if the restrictor window appears green, the air filter is restricted. Technician B says if the restrictor window appears green, the airflow restriction indicator must be replaced. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 2. Air filter service is being discussed. Technician A says the air gun should be held tight against the air filter element when blowing dirt out of the filter. Technician B says when the outside of the air ­filter is observed with a trouble light inside the ­filter, small holes in the filter indicate filter replacement is required. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. All of the following drivability and engine ­problems may be caused by an intake manifold vacuum leak except: A. Rough idle operation B. Low engine operating temperature C. Acceleration stumbles D. Engine detonation 4. A low steady vacuum gauge reading with the gauge connected to the intake manifold may be caused by A. a vacuum leak. B a burned exhaust valve. C. a defective spark plug. D. weak valve springs.

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5. An engine has 19 inch Hg (483 mm Hg) of vacuum in the intake manifold with the engine idling. With the engine running at 2,500 rpm for 3 minutes, the vacuum slowly decreases to 10 inch Hg (254 mm Hg). This problem could be caused by A. a restriction in the catalytic converter or muffler. B. a leak in the exhaust pipe. C. a leak in the intake manifold gaskets. D. a restricted vacuum hose connected to the brake booster.

8. When diagnosing a catalytic converter with the engine running at normal operating temperature A. the converter inlet should be 1508F (658C) hotter than the outlet. B. the converter outlet should be 1008F (388C) hotter than the inlet. C. the converter outlet should be 208F (6.68C) cooler than the inlet. D. the converter inlet should be 508F (198C) ­hotter than the outlet.

6. Removing and replacing an aluminum intake manifold is being discussed. Technician A says the old intake manifold gaskets may be reused. Technician B says a steel scraper should be used to remove old gasket material from an aluminum intake manifold. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

9. While discussing turbocharger inspection and diagnosis, Technician A says excessive turbo shaft ­endplay can cause a rattling noise from the turbocharger. Technician B says that an intake system air leak can damage the turbocharger. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

7. An exhaust manifold with an HO2S sensor is cracked upstream from the sensor. Technician A says this condition does not affect the HO2S sensor signal. Technician B says this condition will damage the HO2S sensor. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

10. While discussing turbocharger performance, Technician A says that worn turbocharger seals can cause blue smoke from the exhaust. Technician B says that a stuck-open wastegate can cause blue smoke from the exhaust. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. With a vacuum gauge connected to the intake manifold, the vacuum gauge reading is a steady 18 inch Hg (457 mm Hg) at idle. When the engine speed is increased to 2,500 rpm, the reading increases to 25 inch Hg (635 mm Hg). Technician A says the engine may have a restricted catalytic converter. Technician B says the EGR valve may be stuck open. Who is correct? A. A only B. B only

2. When a vacuum gauge is connected to the intake manifold, the gauge needle fluctuates between 15 and 20 inch Hg (381 mm Hg) The cause of this problem could be A. late ignition timing. B. intake manifold gaskets leaking. C. a restricted exhaust system. D. sticking valve stems and guides.

C. Both A and B D. Neither A nor B

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3. Technician A says an intake manifold vacuum leak may cause a cylinder misfire with the engine idling. Technician B says an intake manifold vacuum leak may cause a cylinder misfire during hard acceleration. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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5. While discussing turbocharger performance, Technician A says that reduced engine compression can cause reduced boost pressure. Technician B says that an air leak between the turbocharger and the throttle can cause misfire. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Reduced turbocharger boost pressure can be caused by A. a stuck-closed wastegate. B. a stuck-open wastegate. C. a leaking wastegate diaphragm. D. both A and C.

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Name ______________________________________

Date __________________

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JOB SHEET

45

INSPECT AND SERVICE AIR CLEANER Upon completion of this job sheet, you should be able to properly inspect and service air cleaners. NATEF Correlation This job sheet addresses the following AST task for Engine Performance: D.4.

Inspect, service, or replace air filters, filter housing, and intake duct work.

This job sheet addresses the following MAST task for Engine Performance: D.5.

Inspect, service, or replace air filters, filter housing, and intake duct work.

This job sheet addresses the following MLR task for Engine Performance: C.2.

Inspect, service, or replace air filters, filter housing, and intake duct work.

Tools and Materials • Shop towels • Air gun • Shop light • Vehicle with an air cleaner and airflow restriction indicator Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Describe the type of air cleaner mounting and type of filter element: ______________________________________________________________________________ Procedure

Task Completed

1. Remove the air cleaner cover wing nut, clips, or screws, and remove the cover and air filter.

h

2. Place a shop light inside the air filter, and observe the air filter condition. Air filter satisfactory _______________ Requires cleaning _______________ Requires replacement _______________ 3. Inspect the airflow restriction indicator. Window color _______________ Does “Change Air Filter” appear in window?

h Yes  h No

4. Inspect air cleaner housing for cracks, holes, and leaks. Air cleaner housing, satisfactory _______________ unsatisfactory _______________ If air cleaner housing is unsatisfactory, state conditions and necessary repairs. _________________________________________________________________________ 5. Clean the inside of the air cleaner housing with a shop towel, being sure that nothing falls into the air cleaner duct or throttle body. Air cleaner housing properly cleaned ____________________________________ h Yes Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Task Completed 6. Inspect all air intake ducts for cracks, holes, leaks, damage, and deterioration. Air intake ducts, satisfactory _______________ unsatisfactory _______________ If air intake ducts are unsatisfactory, state necessary repairs. _________________________________________________________________________ 7. If the air filter requires cleaning, place an air gun with 30 psi (207 kPa) shop air pressure 6 inches from the inside of the filter and blow the dirt out of the filter. Reinspect the air filter with a shop light. Air filter, satisfactory _______________ Requires replacement _______________ 8. Inspect the sealing surfaces of the air cleaner housing and cover. Do the sealing surfaces of the housing and cover fit squarely against the air filter seals? h Yes  h No If the answer above is no, state necessary repairs. _________________________________________________________________________ _________________________________________________________________________ 9. Install the air filter, air filter cover, and retaining clips, screws, or wing nut.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Intake and Exhaust System Diagnosis and Service

Name ______________________________________

Date __________________

DIAGNOSING VACUUM LEAKS Upon completion of this job sheet, you should be able to properly test a vehicle for vacuum and vacuum leaks, recognize symptoms of a vacuum leak or other problems, and recommend appropriate repairs. NATEF Correlation This job sheet addresses the following AST tasks for Engine Performance: D.5. Inspect throttle body, air induction system, intake manifold and gaskets for vacuum leaks and/or unmetered air. A.5. Perform engine absolute (vacuum/boost) manifold pressure tests; determine necessary action. This job sheet addresses the following MAST tasks for Engine Performance: D.6. Inspect throttle body, air induction system, intake manifold and gaskets for vacuum leaks and/or unmetered air. A.5. Perform engine absolute (vacuum/boost) manifold pressure tests; determine necessary action. This job sheet addresses the following MAST tasks for Engine Performance: A.2. Perform engine absolute (vacuum/boost) manifold pressure tests; determine necessary action. Tools and Materials • Vacuum gauge • Propane tank • Smoke leak detector Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Your instructor will provide you with a specific vehicle. Write down the information; then perform the following tasks: 1. Start the vehicle, and observe the engine idling condition and rpm. Describe your results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Attach a vacuum gauge, and observe the readings at idle and at 2,500 rpm. Describe the readings and the needle movement during the tests. _________________________________________________________________________ _________________________________________________________________________

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3. With the vacuum gauge still installed, hold the engine rpm at 2,500 for one minute and observe the vacuum gauge. Describe your results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Do your tests so far indicate any concerns with the vehicle you are working on?

h Yes  h No

If there are concerns, describe the possible causes. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Next, check the engine for vacuum leaks. Use a smoke leak detector if available or a propane tester if not. Follow the equipment manufacturer’s information for connecting the smoke leak detector to the throttle bore, and apply smoke to the intake. If you are using propane, be certain there are no sources of ignition, and direct the propane at all possible sources of vacuum leaks. Does your vehicle have any vacuum leaks?

h Yes  h No

If your vehicle does have a vacuum leak, describe the source of the problem and the recommended repair. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Attach a vacuum gauge to a port on the intake manifold or another source of manifold vacuum. Start the vehicle, and disconnect a vacuum line from the intake manifold. Describe the change in the idle condition and vacuum reading from your previous test. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 7. Turn the engine off, replace the vacuum line, and remove all test equipment. Start the engine, and be sure that it runs as smoothly as it did when you began your testing. _________________________________________________________________________ 8. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Intake and Exhaust System Diagnosis and Service

Name ______________________________________

Date __________________

EXHAUST SYSTEM INSPECTION AND TEST Upon completion of this job sheet, you should be able to properly inspect an exhaust system and determine the necessary repairs. NATEF Correlation This job sheet addresses the following AST task for Engine Performance: D.8. Inspect integrity of the exhaust manifold, exhaust pipes, muffler(s), catalytic converter(s), resonator(s), tail pipe(s), and heat shields; determine necessary action. This job sheet addresses the following MAST task for Engine Performance: D.9. Inspect integrity of the exhaust manifold, exhaust pipes, muffler(s), catalytic converter(s), resonator(s), tail pipe(s), and heat shields; determine necessary action. This job sheet addresses the following MLR task for Engine Performance: C.3. Inspect integrity of the exhaust manifold, exhaust pipes, muffler(s), catalytic converter(s), resonator(s), tail pipe(s), and heat shields; determine necessary action. Tools and Materials • Gasoline engine vehicle with an exhaust system • Digital pyrometer • Vacuum gauge Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Describe the type of exhaust system on the vehicle: ______________________________________________________________________________ Procedure 1. Inspect the HO2S (heated oxygen sensor) sensor wiring.

HO 2S sensor wiring, satisfactory _______________ unsatisfactory _______________ If the HO 2S wiring is unsatisfactory, state necessary repairs. _________________________________________________________________________ 2. Inspect exhaust manifold(s) for cracks and exhaust leaks. Exhaust manifold(s), satisfactory _______________ unsatisfactory _______________ If exhaust manifold(s) are unsatisfactory, state necessary repairs. _________________________________________________________________________

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3. Inspect exhaust pipe, muffler, and tailpipe for holes, cracks, leaks, kinks, dents, separated connections, and excessive rust. Exhaust pipe, satisfactory _______________ unsatisfactory _______________ Muffler, satisfactory _______________ unsatisfactory _______________ Tailpipe, satisfactory _______________ unsatisfactory _______________ If the exhaust pipe, muffler, and/or tailpipe are unsatisfactory, state necessary repairs. _________________________________________________________________________ 4. Inspect all exhaust system hangers and clamps. Hangers and clamps, satisfactory _______________ unsatisfactory _______________ If the hangers and/or clamps are unsatisfactory, state necessary repairs. _________________________________________________________________________ 5. Perform exhaust system restriction test. Intake manifold vacuum at idle speed _______________ Intake manifold vacuum at 2,500 rpm after 3 minutes _______________ Exhaust system restriction, satisfactory _______________ unsatisfactory _______________ If exhaust system restriction is unsatisfactory, state necessary corrective action. _________________________________________________________________________ 6. Perform catalytic converter test with engine at normal operating temperature. You must drive the vehicle under a load to properly precondition the catalytic converter and ensure that it is hot enough to be functional. An extended period of idling may allow the converter to cool down enough to become inefficient. Converter inlet temperature _______________ Converter outlet temperature _______________ Converter, satisfactory _______________ unsatisfactory _______________ If the converter is unsatisfactory, state necessary repairs. _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Intake and Exhaust System Diagnosis and Service

Name ______________________________________

Date _______________

JOB SHEET

TURBOCHARGER SYSTEM INSPECTION Upon completion of this job sheet, you should be able to perform a proper inspection of the turbocharger system and determine needed repairs. Tools and Materials • Vehicle with a turbocharger Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Your instructor will assign you (or your group) to a turbocharger-equipped vehicle. Using the proper service manual, you will identify the required steps to inspect the turbocharger system. WARNING  If the engine has been running, turbochargers and related c­ omponents are extremely hot. Use caution and wear protective gloves to avoid burns when servicing these components. 1. Inspect the wastegate diaphragm linkage for looseness and binding. Record your results. _________________________________________________________________________ _________________________________________________________________________ 2. Check the hose from the wastegate diaphragm to the intake manifold for cracks, kinks, and restrictions. Record your results. _________________________________________________________________________ _________________________________________________________________________ 3. Check the coolant hoses and oil line connected to the turbocharger for leaks. Record your results. _________________________________________________________________________ _________________________________________________________________________ 4. Check the engine oil level for proper fill and condition. Record your results. 5. Check for oil leakage at the end housings of the turbocharger. Is oil leaking?

h Yes  h No

6. Check the oil drain tube and engine crankcase breathers for restrictions. Record your results. _________________________________________________________________________ _________________________________________________________________________ 7. Check all turbocharger mounting bolts for looseness, and tighten to specifications as needed.

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h

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Chapter 7

8. Start the engine. After oil pressure is obtained, accelerate the engine while observing the tailpipe for excessive blue smoke. Is blue smoke present?

h Yes  h No

9. While the engine is running, listen for any unusual turbocharger noises. Record your results. _________________________________________________________________________ _________________________________________________________________________ 10. Listen for any exhaust leaks. Record your results. _________________________________________________________________________ _________________________________________________________________________ 11. Check for intake system leaks. Record your results. _________________________________________________________________________ _________________________________________________________________________ 12. Check the high-pressure side of the turbocharger system for leaks using soapy water. Record your results. _________________________________________________________________________ _________________________________________________________________________ 13. If the boost pressure is computer controlled, check and record any diagnostic trouble codes (DTCs). _________________________________________________________________________ _________________________________________________________________________ 14. Shut off the engine, and remove the air cleaner and the ducting from the air cleaner to the turbo. Look for dirt buildup and damage from foreign objects. Record your results. _________________________________________________________________________ _________________________________________________________________________ 15. Once the turbocharger has fully cooled, inspect the wheels for free rotation. Also, look into the housing and visually inspect for signs of wheel-to-housing interference. Record your results. _________________________________________________________________________ _________________________________________________________________________ 16. Based on your results, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date __________________

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JOB SHEET

49

TESTING BOOST PRESSURE Upon completion of this job sheet, you should be able to perform a boost pressure test of the turbocharger system and determine needed repairs. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Performance: A.5. Perform engine absolute (vacuum/boost) manifold pressure tests; determine necessary action. This job sheet addresses the following MLR task for Engine Performance: A.2. Perform engine absolute (vacuum/boost) manifold pressure tests; determine necessary action. Tools and Materials • Vehicle with a turbocharger (nonelectric motor) • Vacuum/pressure hand pump • Pressure gauge • Dial indicator Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will assign you (or your group) to a turbocharger-equipped vehicle. Using the proper service manual, you will identify the required steps to test the boost pressure. 1. What is the specification for boost pressure? ____________________________________ 2. Connect a pressure gauge to the intake manifold. The pressure gauge hose should be long enough so the gauge may be positioned in the passenger compartment.

h

3. Road test the vehicle at the speed specified by the vehicle manufacturer, and observe the boost pressure. Record the amount of boost indicated on the pressure gauge. _________________________________________________________________________ 4. Is the boost pressure within specification? If No, continue to step 6.

h Yes  h No

5. Check the actuator rod for bends that would prevent free movement. Record your results. _________________________________________________________________________ 6. Check for carbon buildup that prevents the valve from closing or causes it to bind. Record your results. _________________________________________________________________________

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7. Before condemning the wastegate, perform some basic checks of the ignition and fuel systems. Check ignition timing, the spark retard system, vacuum hoses, the knock sensor, the O 2 sensor, and fuel delivery to ensure all are operating properly. Record your results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Test the stroke of the wastegate actuator rod. Connect a hand pressure pump and a pressure gauge to the wastegate diaphragm. Position a dial indicator on the outer end of the actuating rod so it can measure rod movement. While supplying the specified amount of pressure with the hand pump, read the dial indicator and note the amount of movement. Specifications _______________ At what pressure is the specification? _______________ Actual rod movement measurement _______________ 9. Will an adjustment of the rod length correct the amount of rod movement?

h Yes  h No

10. If No, what needs to be done to correct the problem? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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CHAPTER 8

ENGINE REMOVAL, ENGINE SWAP, AND ENGINE INSTALLATION

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■ ■■ ■■ ■■

The steps required to prepare the engine for removal. How to remove an engine from a ­front-wheel-drive (FWD) vehicle. How to remove an engine from a ­rear-wheel-drive (RWD) vehicle.

■■

How to determine the proper engine cleaning methods. How to remove the engine accessories in preparation for engine repair or replacement.

■■

■■ ■■

How to remove and reinstall engine accessories for the installation of a rebuilt or remanufactured engine. How to install an engine on a stand. How to install an engine in a frontwheel-drive vehicle.

Basic Tools Basic mechanic’s tool set Service manual

How to install an engine in a rearwheel-drive vehicle.

Terms to Know Engine hoist Engine stand

Exhaust gas recirculation (EGR) valve

Purge solenoid Steam cleaner

INTRODUCTION Most engine rebuild operations require the removal of the engine from the vehicle. The procedure and tools used to remove the engine depend upon the vehicle’s design. Most rear-wheel-drive vehicles require the engine to be removed from the hood opening, while many front-wheel-drive vehicles require engine removal from the bottom of the vehicle. This chapter discusses the basic steps required to prepare an engine for removal and for removing it from the vehicle. The typical procedures for removing an engine from a front-wheel-drive and rear-wheel-drive vehicle are discussed. In addition, general engine disassembly procedures are discussed.

PREPARING THE ENGINE FOR REMOVAL WARNING  Cleanliness is important when removing an engine. To prevent injury, keep your work area clean. If fluids are spilled or grease falls to the floor, clean it up immediately.

Before beginning the job of removing an engine from the vehicle, be sure to place fender covers on both sides and in the front of the vehicle (Figure 8-1). A big scratch on the fender would cost you or your shop money, and understandably, the customer would be upset.

Classroom Manual Chapter 8, page 168

Special Tools Steam cleaner or pressure washer Fender covers Battery terminal puller Drain pans Antifreeze recycler A/C reclaimer/ recycler

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Figure 8-1  Don’t let a careless mistake harm your reputation as an excellent engine repair technician.

A steam cleaner uses hot, pressurized water to clean an engine or other components.

Caution Perform the engine cleaning process where a drain trap or waste water recycler is available.

Caution To prevent damage when steam cleaning an engine avoid contact with air-conditioning and electrical components.

The work of removing an engine from the vehicle is much cleaner if you can wash the engine and the engine compartment first. Many shops will wash every engine and engine compartment during major engine service because the customer is always pleased to see the engine “look like new.” Other shops choose not to clean engines before removal, due to concerns about component damage and/or environmental regulations or concerns. Always consult local regulations and the vehicle service information for precautions and warnings before cleaning. You will need to protect electrical components such as the starter and generator. There may be additional electronic components such as computers or sensors that also need to be removed or thoroughly covered. Follow the equipment manufacturer’s instructions when using a steam cleaner, pressure washer, or cleaning chemicals to clean the engine. Study the service information to determine what tools and equipment will be required to remove the engine, and to become familiar with the procedure for the vehicle you are working on. Until you have had a lot of practice, follow the service information’s step-bystep procedure to be sure that you do not miss anything. Often you will have to remove bolts that you can feel but not see. You could cause damage to components if you attempt to lift the engine with anything still attached. With the vehicle centered in the service bay or over a frame contact hoist, perform the following steps to complete the preparation process: WARNING The steps described in this book are typical steps in preparing the engine for removal. Always refer to the service manual for all procedures and become familiar with all warnings and safety concerns.

1. Disconnect the battery negative terminal and isolate the cable. Remove the positive terminal next and then remove the battery.

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Engine Removal, Engine Swap, and Engine Installation

CUSTOMER CARE  Disconnecting the battery will erase radio station presets. Before disconnecting the battery, take a few minutes to write down the presets. Before returning the vehicle to the customer, reset the radio stations. WARNING  Before disconnecting any electrical components or removing wire harnesses, always disconnect the battery first. Always disconnect the negative battery terminal first when removing the battery and connect it last when installing the battery. If the positive battery terminal is removed first, the wrench may slip and make contact from this terminal to ground. This action may overheat the wrench and burn the technician’s hand. Arcing near a battery can also cause it to explode. WARNING  Never wear jewelry when working around the vehicle. Gold, silver, and copper are excellent conductors of electricity. In addition, your body is also a conductor of electricity. If the jewelry makes contact with a current-carrying wire or terminal, severe injury may result. Also, jewelry may become caught on objects or in fans and other rotating parts.

2. If the hood must be removed, mark the location of the hinge to the hood for ­reference during assembly and then remove the hood and place it in a safe place (Figure 8-2). 3. Lift the vehicle on the hoist and drain the engine oil. 4. Drain the engine coolant from the radiator and engine block. Removing the radiator cap will increase the flow of coolant through the drain.

Figure 8-2  Mark the hood before removal so it can be easily reinstalled in correct alignment.

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WARNING  Do not open a radiator cap if the engine is warm. The release of hot coolant under pressure can cause serious burns.

5. If the transmission is being removed with the engine, drain its fluid. Disconnect shift linkages, transmission cooling lines, any vacuum hoses, clutch linkages, and drive shaft. 6. Disconnect the lower radiator hose and the transmission cooling lines (if needed). 7. If easily accessible while the vehicle is on the hoist, disconnect the cooling lines to the heater core. 8. Disconnect the exhaust system. Attempt to do this at the exhaust manifold if possible. 9. Disconnect any additional wiring harnesses, vacuum hoses, and cables that are easier to get to while the vehicle is on the hoist. Use some sort of identifying method to assure proper connections during engine replacement (Figure 8-3). 10. Lower the vehicle and remove the air intake ducts and air cleaner assembly (Figure 8-4). 11. Follow the service manual procedure to relieve fuel pressure. If a procedure is not listed in the service manual, attach a drain hose to the Schrader valve on the fuel rail. The other end of the drain hose must go into an approved container. When the pressure is completely relieved, disconnect the fuel feed line from the fuel rail. If the engine is equipped with a return fuel line from the pressure regulator, disconnect it also. To prevent fuel leakage, plug the fuel lines. Most modern vehicles use a quick-connect fitting on the fuel lines (Figure 8-5). These are separated by squeezing the retainer tabs together and pulling the quick-connect fitting assembly off of the fuel line nipple. The retainer will remain on the fuel line (Figure 8-6). 12. Disconnect the throttle cable to the throttle body (Figure 8-7). 13. Remove any accessory drive belts.

Figure 8-3  Take the time to label electrical connectors and hoses during removal; doing so takes a lot less time than trying to figure out where everything should be reinstalled without clues. After a few engine removals, you will learn shortcuts that save time. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Removal, Engine Swap, and Engine Installation

Intake ductwork

Air filter housing

Figure 8-5  These fuel lines have quick-disconnect fittings that come apart easily with the proper tool.

Figure 8-4  Remove the intake air filter housing and ductwork.

Figure 8-6  Typical quick-disconnect fitting tools for fuel systems and other applications.

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Figure 8-7  Disconnect the throttle cable.

14. If the air-conditioning compressor needs to be disconnected from the pressure hoses, the system must be evacuated into a reclaimer unit. Follow all instructions and safety procedures provided by the equipment manufacturer. In most cases, the compressor and bracket can be removed from the engine and wired off out of the way without disconnecting any lines. 15. Disconnect the air-conditioning compressor bracket, power steering unit, AIR pump, cruise control activators, and any other components that are attached to the engine block. Identify all wires or hoses that are disconnected, and cap any hoses that may leak fluid. If possible, lay the component to the side and secure it instead of disconnecting it and removing it from the engine compartment (Figure 8-8). 16. Disconnect the upper radiator hose. 17. Disconnect the electric cooling fan motor connector; then remove the radiator mounting. The radiator and cooling fans can usually be removed as a unit (Figure 8-9). 18. Disconnect any other wiring harnesses and vacuum hoses as required. Identify each connection. There may be individual connectors to each of the engine sensors and actuators; be sure to label them accordingly. Some engines use one or two large connectors to allow the engine harness to be disconnected from the chassis. If ­possible, disconnect the complete engine wiring harness at the bulkhead connector(s). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 8-8  Whenever possible, remove components as assemblies and secure them in the engine compartment.

Mounting brackets FRONT

Radiator

Caution Never intentionally discharge the air-conditioning system into the atmosphere. The refrigerant used in these systems when vented has an environmental impact. As a professional employed within an industry traditionally associated with hazardous materials, it is your responsibility to conduct yourself in such a manner as to protect the environment and to improve the public perception of the industry. Also, severe penalties or fines can be issued for intentional discharge of any type of refrigerant except for R-744. Only tested and certified technicians can use recover/recycle/ recharge equipment.

Lower radiator supports Connector Lower cushion Motor coolant fan ATF cooler lines Lower cushion

Figure 8-9  Remove the cooling fan and radiator assembly to prevent damage during engine removal.

Additional steps may include removing the distributor cap and wires, the distributor, and the water pump. The service manual is always your best source of information concerning engine removal procedures.

SERVICE TIP  When removing components from the engine, it is faster to remove assemblies rather than individual components. Also, it may not be necessary to remove all items from the engine compartment. The power steering pump, air-conditioner compressor, cruise control servo, and so forth can be tied off to the side.

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REMOVING THE ENGINE At this point, the procedure will vary depending on whether the engine is removed from the bottom of the vehicle or through the hood opening. Many front-wheel-drive vehicles require removal of the engine through the bottom, while most rear-wheel-drive vehicles require the engine to come out the top. In addition, different steps are required between front- and rear-wheel-drive vehicles. When removing the fasteners, pay close attention to their size and type. Many of the brackets used to secure the engine or accessories use several different size fasteners. Mark the fasteners so their proper location can easily be determined during reassembly. It is best to place fasteners in the same location to prevent mixing them. Many manufacturers use a crankshaft position sensor attached above the flywheel or flexplate. This sensor must be removed before separating the engine from the bellhousing to prevent damage. SERVICE TIP  If the radiator is not made from aluminum or copper, clean it in an acid solution to remove scale from the inside of the tubes and tanks. Installing a dirty radiator in a fresh engine can cause early engine failure.

Front-Wheel-Drive Vehicles In addition to the steps performed in preparing the engine for removal, the following steps may be required on FWD vehicles before the actual process of removing the engine is started (refer to Photo Sequence 17 for picture-by-picture steps of a typical FWD engine removal): 1. Remove the cross member (center beam) (Figure 8-10). 2. Disconnect the outer tie rod ends (Figure 8-11). Refer to the service manual for the proper procedure. 3. Disconnect the lower ball joint from the steering knuckle (Figure 8-12). 4. Remove the axles from the hubs and transaxle.

Classroom Manual Chapter 8, page 168

If the engine is removed from the hood opening, perform steps 1 through 4; then refer to the section on rear-wheeldrive vehicles for the hoisting procedure.

Caution When setting the frame contact hoist, consideration must be made concerning weight transfer with the engine removed.

Axle

Front beam

Center beam

Figure 8-10  To remove the engine from a front-wheel-drive vehicle, it may be necessary to remove portions. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Special tool

Steering knuckle

Tie rod end Lower ball joint

Steering knuckle

Lower control arm

Figure 8-11  Use a tie rod end removal tool to disconnect the tie rod from the steering knuckle.

Figure 8-12  You may need to remove the lower ball joints to get the axles out.

PHOTO SEQUENCE 17

Typical Procedure for FWD Engine Removal

P17-1  Disconnect negative cable first and then the positive cable; then remove the battery and battery holder.

P17-2  Remove the intake ducting and necessary vacuum lines and electrical connectors.

P17-3  Remove all throttle linkages.

Fuel supply line

P17-4  Relieve fuel pressure and disconnect the fuel supply (and return if applicable) line.

P17-5  Disconnect and label all necessary vacuum lines, electrical connectors, and fluid lines.

P17-6  Remove the wheels.

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PHOTO SEQUENCE 17 (CONTINUED)

P17-7  Disconnect the lower ball joints from the spindles.

P17-10  Remove the axles from the hubs, and pop them out of the transaxle.

P17-8  Remove the axle nuts.

P17-9  Remove the wishbone links.

P17-11  Remove the speedometer cable and other connections on the transaxle and engine.

P17-12  Remove the exhaust.

P17-13  Support the engine, and remove the suspension and engine cradle.

P17-14  Use the engine hoist to lower the engine and transaxle onto the dolly underneath the vehicle. Make sure everything is disconnected; then raise the vehicle from the power plant.

When the engine is removed through the bottom of the vehicle, use a special engine cradle and dolly to support the engine. If the vehicle manufacturer recommends engine removal through the hood opening, use an engine hoist (Figure 8-13). Regardless of the method of removal, the engine and transaxle are usually removed as a unit. 5. Adjust the pegs of the cradle to fit into the holes in the bottom of the engine block. 6. Remove the engine mount fasteners (Figure 8-14).

Special Tools Fender covers Taper breaker Engine cradle Engine dolly

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Engine block Engine mount bracket

Engine mount

Frame

Figure 8-13  Some front-wheel-drive vehicles require the engine to be removed from the hood opening. Use an engine hoist to lift the engine.

Figure 8-14  One of the last steps is to remove the engine mounts.

7. If required, remove the frame member from the vehicle (Figure 8-15). On some vehicles, the frame member affects wheel alignment—mark its position before removing the bolts. It may be necessary to disconnect the steering gear from the frame member. 8. Double-check to ensure that all wires and hoses are disconnected from the engine. 9. Lift the vehicle using a frame contact hoist. As the vehicle is lifted, the engine remains on the cradle. During this process, continually check for interference with the engine and vehicle body. Also watch for any wires or hoses that may still be attached to the engine.

Rear beam

Center beam

Front beam

Figure 8-15  Some or all of the engine cradle’s frame members may need to be removed to lower the engine through the bottom of the vehicle.

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SERVICE TIP  If the engine removal process requires the use of an engine hoist, make sure it is capable of lifting the weight of the engine to a height sufficient to clear the engine compartment. Remember that the engine oil pan hangs low below the engine block, and as the weight of the engine is removed from the ­vehicle’s suspension system, the body height will increase.

Rear-Wheel-Drive Vehicles The engine is removed through the hood opening on most RWD vehicles, requiring the use of an engine hoist. Refer to the service manual to determine the proper engine lift points. If the transmission is being removed with the engine, it may be easier if you locate the hook of the engine hoist to the chain in such a manner that the engine tips a little toward the transmission. Additional preparation steps depend on whether the engine and transmission are being removed together or if the engine is being removed alone. If the transmission is not being removed with the engine, support it with a transmission stand. Remove the bellhousing bolts and inspection plate. On vehicles equipped with automatic transmissions, remove the torque-converter-to-flexplate bolts. Use a C-clamp or other brace to prevent the torque converter from falling. Also, mark the location of the torque converter in relation to the flexplate for reference during installation.

TYPICAL PROCEDURE FOR RWD ENGINE REMOVAL

An engine hoist is a crane style pump jack that is specially designed to lift an engine out of a vehicle.

Special Tools Fender covers Engine hoist Chain or sling C-clamp Transmission stand or jack

If the transmission is being removed with the engine, remove the drive shaft after making an index mark with the companion flange at the differential. Disconnect the rear engine mount (Figure 8-16). Disconnect all shift and/or clutch levers. After performing the preceding steps to prepare the engine for removal, follow the typical steps shown in Photo Sequence 18 to remove the engine through the hood opening on most RWD vehicles. WARNING  Do not lift the engine by the intake manifold. Use the proper hooks, brackets, or fixtures. This action may break the intake manifold or retaining bolts, causing the engine to drop suddenly and result in technician injury.

Special Tools Engine stand Engine hoist

Transmission

Rear engine mount

Engine mount bracket Crossmember

Figure 8-16  The rear engine mount will have to be disconnected if the transmission is coming out with the engine.

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PHOTO SEQUENCE 18

Typical Procedure for RWD Engine Removal

P18-1  Tools required to perform engine removal include fender covers, lifting strap or chain, basic mechanic’s tools, and an engine hoist.

P18-4  Double-check to ensure that all wires and hoses are disconnected from the engine.

A engine stand is a special holding fixture that attaches to the back of the engine. It allows the engine to be supported at a comfortable working height.

P18-2  Attach the engine lifting fixture to the engine.

P18-5  Lift the engine from the vehicle.

P18-3  Disconnect the engine mounts.

P18-6  During this lifting process, continually check for interference with the engine and vehicle body. Also watch for any wires and hoses that may still be attached to the engine.

To begin the disassembly process, attach the engine to an engine stand (Figure 8-17). If the transmission or transaxle was removed with the engine, it will be necessary to separate it from the engine first. Before removing the flywheel or flexplate, mark its reference to the crankshaft. Bolt the adjustable arms of the engine stand to the bellhousing attaching holes. Never work on the engine while it is hanging from the hoist.

Figure 8-17  Proper installation of the engine to the stand is critical to your safety. Check the weight rating of the stand and thread the bolts in at least the distance equal to one and a half times the bolt diameter. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Removal, Engine Swap, and Engine Installation

WARNING  Check the load rating of the engine stand to ensure it will be able to maintain the weight of the engine being installed. SERVICE TIP  When attaching the engine to the engine stand, make sure the distance the bolts thread into the engine block is at least one and a half times the diameter of the bolt.

INSTALLING A REMANUFACTURED ENGINE In many cases you or your shop management will decide that it will be economically more profitable to install a remanufactured “crate” engine rather than to rebuild the existing engine in house. Remanufactured engines come with a warranty that relieves the shop of the liability that an error in your overhaul could cost the shop as well. With popular engines that are readily available as remanufactured units, this is definitely the trend in the automotive repair business. A crate engine, as the name implies, comes in a crate fully assembled (Figure 8-18). You will need to swap over to the “new” engine all of the engine accessories, sensors, actuators, and manifolds, and often oil pans, valve covers, and other components. The best method of approaching the preparation of the new engine is to have it side by side with the old engine. Then you will know precisely what has to be removed from the old engine and installed on the new one. You will also be able to see exactly how the component mounts on the engine and to transfer it directly. It is always a good idea to check the manufacturer’s technical service bulletins (TSBs) for information related to engine installation and removal. Organizations such as the Automotive Engine Rebuilders Association (AERA) will also offer advice in the form of TSBs that may be considered helpful when installing a crate engine (refer to Photo Sequence 19 for picture-by-picture steps of a typical procedure for mounting an engine on a stand).

Figure 8-18  Crate engines are available at aftermarket parts stores as well as from the manufacturer. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 19

Mounting the Engine on a Stand

P19-1  Locate the engine and crane near the engine stand.

P19-4  Securely tighten the mounting bolts. They should extend into the engine at least as far as one and a half times the width of the bolt.

P19-2  Adjust the mounting flange ears to fit the engine.

P19-5  Slide the mounting flange tube into the engine stand.

P19-7  Remove the engine hoist and the chain.

P19-3  Mount the flange onto the engine.

P19-6  Secure the engine with a pin through the stand and the flange.

P19-8  Now the engine is secure on the stand and ready for repair work.

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Engine Removal, Engine Swap, and Engine Installation

Generator

355

Water pump

Weep hole Power steering pump

Crankshaft pulley

Figure 8-20  This pump has been seeping past the weep hole, so it should definitely be replaced.

Figure 8-19  Start removing components from the front end of the old engine and installing what is good onto the new engine.

1. Start by disassembling the front end of the engine and removing the belt(s) hoses, lines and generator, power steering pump, air-conditioning compressor, and water pump (Figure 8-19). Some of these items may be hanging in the engine compartment, and you will reinstall them during the engine installation. Provided these components are in good condition, install them onto the new engine. If the crate engine does not come with a new water pump, it is customary to fit a new one at this point unless it has been replaced recently (Figure 8-20). Fit a new gasket using sealant only if it is recommended, and torque the water pump to the proper ­specification (Figure 8-21). 2. Remove the crankshaft pulley and harmonic balancer. Simply remove the bolts attaching the crankshaft pulley, and pull it off (Figure 8-22). To remove the ­harmonic balancer, first remove the attaching bolt from the center of the pulley. Use a flywheel holder to keep the engine from turning; this bolt will be on tight

Crankshaft pulley

Balancer

Figure 8-21  Install the new pump and attach the hoses. Be sure the clamps are in good condition or replace them.

Figure 8-22  Remove the crank pulley for installation on the new engine.

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Special Tools Crankshaft dampener puller Crankshaft dampener installer Flywheel turning bar

(Figure 8-23). Once the bolt is removed, you will likely need to use a puller (Figure 8-24). Make sure the harmonic balancer is in good shape; the keyway should not be rounded, and the rubber must not be separating between the inner and outer sections. Use an installation tool to press the balancer onto the new engine (Figure 8-25). Reinstall the crankshaft pulley, and install a new accessory drive belt. You may need to follow the routing directions labeled under the hood. Release the tensioner, and route the belt properly around all the pulleys (Figure 8-26). Allow the tensioner to tighten the belt if it is automatic, or tighten the belt to specification using a manual tensioner. Confirm proper tension of the belt(s) using a belt tension gauge. Reinstall any other hoses and lines that were attached to the front of the engine. Check their condition and replace as needed. Remember that the customer will not want to bring his vehicle back for service in the near future after this big job. If a component is questionable, replace it.

Crankshaft vibration damper

Attachment bolt

Figure 8-24  You will have to use a puller to remove most harmonic balancers. Be sure to place a round plug puller attachment at the end of the crankshaft to protect the threads.

Figure 8-23  Use a flywheel holder to hold the engine, and remove the harmonic balancer attaching bolt.

Generator Tensioner

Water pump

AC compressor

Power steering pump

Special installation tool Idler pulleys

Figure 8-25  Use a special installation tool to protect the crankshaft when reinstalling the balancer.

Figure 8-26  Route the belt carefully, and then check the tension with a belt tension gauge.

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Engine Removal, Engine Swap, and Engine Installation

3. Remove any components from the top of the engine. This typically includes many brackets, sensors, and solenoids (Figure 8-27). Remove them one by one, and install them directly onto the new engine to avoid confusion about brackets and placement. The ignition system components must be swapped over whether the system uses a coil for each plug, an individual coil with a distributor, or a coil pack (Figure 8-28). Carefully inspect the wires for nicks or wear points or any signs of a gray powdery residue where the wire could have been arcing to ground. If the

Throttle position sensor Intake air temperature sensor

Engine coolant sensor

EVAP purge control solenoid

Idle air control (IAC) Manifold absolute pressure sensor

PCV valve

Ignition control module (ICM)

Power steering pressure switch

Top dead center/crankshaft position/cylinder position (TDC/CKP/CYP) sensor Knock sensor

Heated oxygen sensor (HO2S)

Figure 8-27  A modern engine has many sensors, switches, and solenoids that will have to be swapped over.

Corrosion

Figure 8-28  The corrosion on tower number one warrants replacement. That could easily cause an ignition misfire. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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The exhaust gas recirculation (EGR) valve is an emission control device that cools the combustion chamber to reduce oxides of nitrogen emissions. The purge solenoid is part of the evaporative emissions control system and is used to purge fuel vapors from the fuel tank into the intake manifold to be burned with the air-fuel mix.

engine is equipped with an exhaust gas recirculation (EGR) valve, you will need to remove it from the engine (Figure 8-29). Clean the bottom of the EGR valve with a wire brush to remove carbon from the pintle. You will also need to remove and install solenoids such as the purge solenoid (Figure 8-30). You will need to install several sensors and vacuum lines on the new engine (Figure 8-31). It may be possible to remove the fuel rail, fuel-pressure regulator, and injectors as an assembly and install it onto the new engine (Figure 8-32). Carefully check for any other components left on the old engine that are not installed on the new engine. 4. Remove the intake manifold, and install it with a new gasket and the proper sealant if specified (Figure 8-33). Carefully lower the manifold into place without disturbing the gasket(s). Use the correct tightening sequence and torque specification (Figure 8-34). Swap the exhaust manifold to the new engine using a gasket if required and torque it properly (Figure 8-35). Be sure to use new studs and mounting hardware; the used hardware is usually damaged by rust. 5. If needed, swap the oil pan and valve covers onto the new engine. If the old engine was badly damaged, it may be quite a task to get the oil pan clean (Figure 8-36). Be sure to do an excellent job of cleaning it inside and out, to protect the new engine

Figure 8-29  A typical EGR valve.

Figure 8-30  A purge control solenoid for the evaporative emissions control system.

Figure 8-31  Install all the sensors and vacuum lines onto the new engine.

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O-ring seals

Fuel rail

Fuel-pressure regulator

Fuel injectors

Figure 8-32  This came apart as an assembly. Be sure to check the injector O-ring seals for damage and to lubricate them sparingly with petroleum jelly prior to installation.

Rear intake manifold seal

Intake manifold gasket

Silicon rubber sealer applied at each end of seal

Front intake manifold seal

Figure 8-33  Install the new intake manifold with any sealants specified.

1

3

5 6 4 2 8

7

Bolt

Intake manifold

Figure 8-34  Torque the intake manifold into place using the specified (if available) or typical torque sequence.

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Figure 8-35  Many technicians will clean and paint the old manifolds and covers to make the whole engine look like new.

Figure 8-36  This oil pan will require quite a bit of work before it will be suitable for installation on the new engine.

and to please the customer. Use new gaskets and torque the oil pan into place using the appropriate sequence and proper torque specification. Similarly, clean and ­properly install the valve cover(s) with new gaskets and torque them properly (Figure 8-37).

SERVICE TIP  Before and after transferring parts to a rebuilt or replacement engine make sure the engine turns over by hand to check for any possible problems.

6. Once you have the new engine assembled, you can bolt the flywheel or flexplate onto the back of the engine. Be sure to tighten these properly to avoid additional work and a frightening knock (Figure 8-38). On a manual transmission vehicle, this is an excellent opportunity to inspect the clutch disc and pressure plate (Figure 8-39). If it is significantly worn, now is

Flex plate

Crankshaft

Figure 8-37  Use a high-quality gasket and torque properly to avoid leaks that could bring the customer back dissatisfied.

Figure 8-38  The flexplate or flywheel attaches to the rear of the crankshaft.

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Pressure plate and cover assembly

Aligning tool

Flywheel

Clutch disk

Pressure plate

Figure 8-40  Use a clutch aligning tool to be sure the engine and transmission slide together.

Figure 8-39  Replace the clutch components if they are worn. Doing so now will be a lot cheaper than doing so after the transmission and engine are reinstalled.

the time to replace the clutch assembly. The labor to install a clutch later is quite costly; right now it is basically free. Use a clutch aligning tool to line up the clutch disc (Figure 8-40). Then tighten the pressure plate in a diagonal or star fashion to the specified torque. Torquing the bolts around in a circle can warp a brand-new pressure plate due to the spring tension. 7. Make a final check of the old engine to be sure that you have transferred all the required parts. Inspect the new engine to be sure you have tightened everything and installed it properly. Next you will install it back into the vehicle.

Caution Overtightening the oil filter may cause seal damage and result in oil leakage.

If the engine uses a mechanical fuel pump operated off an eccentric on the camshaft, install it. On some designs, the arm of the fuel pump must ride on top of the eccentric, while on other designs, it must ride on the bottom of the eccentric. Some engines use a rod between the camshaft eccentric and pump arm. The rod must be held up against the camshaft as the fuel pump is installed. To complete the assembly, lubricate the oil filter gasket and fill the filter with oil. Install the oil filter. Do not overtighten the filter. Turn the filter three-quarter turn after the seal makes contact.

INSTALLING THE ENGINE The process of engine installation is the next step. Before placing the engine into the vehicle, double-check all work thus far to be sure there are no loose fasteners or connections. When ready, locate the vehicle in the center of the service bay or over a frame contact hoist. Remove the engine from the engine stand, and attach it to the engine hoist. It may be easier to install the transmission on the engine before placing the engine into the vehicle. Regardless of when the transmission is installed, it must be properly centered before the bolts are torqued. When the transmission is attached to the engine, it should fit up to the block. If it does not fit up to the block, the clutch is not properly aligned. Automatic transmissions use torque converters to make the link between the engine and the transmission. The torque converter should be installed onto the front pump of the transmission before the transmission is installed to the engine. Installing the torque converter to the flexplate first makes aligning the pump shafts into the converter difficult and may result in pump or converter damage. Align the scribe marks made between the flexplate and torque converter during disassembly. The process of installing the engine into the vehicle is basically a reversal of the removal process. The same safety concerns applying to engine removal also apply to Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Special Tools Engine cradle and dolly Hoist

installing the engine. As with engine removal, the procedures vary between front-wheel and rear-wheel-drive vehicles. The procedure given here for front-wheel-drive vehicles assumes the engine is to be installed from under the vehicle. If the engine is installed from the hood opening, the procedure of placing the engine into the vehicle is similar to rearwheel-drive vehicles.

Front-Wheel-Drive Vehicles

Caution When setting the frame contact hoist, remember to consider the weight transfer with the engine installed.

Caution Never use the bolts to draw a transmission up to the engine. They should slide together by hand. If the transmission does not seat, remove it and realign the clutch disc.

Many front-wheel-drive vehicles require the installation of the engine through the bottom of the vehicle. Prepare for engine installation by installing the engine into the cradle and dolly (if needed). Lift the vehicle on the hoist, and position the engine under the vehicle. Slowly lower the vehicle over the engine while guiding wires and hoses out of the way. As the vehicle and engine approach each other, align the engine and transmission mounts. This may require some shaking of the engine. Be careful not to damage any steering or suspension components. When the engine mounts are aligned, install the mounting bolts into the motor mounts (Figure 8-41). The vehicle can now be lifted to a comfortable working height.

SERVICE TIP  When replacing a part, always thread all of the bolts in by hand before torquing the first one down.

SERVICE TIP  To assist lining up the engine mounts with the bushing, try using a long aligning punch. The punch is strong and can help move the engine in just the right direction.

SERVICE TIP  Because water is easier to clean up than antifreeze, fill the radiator with pure water until it is determined there are no leaks.

Engine mount bracket

Engine mount

Figure 8-41  As you locate the engine in the engine compartment, line up the engine mounts before dropping the engine into place.

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Exhaust pipe Axle shafts

Front beam

Center beam

Figure 8-42  Lift the vehicle to reassemble the bottom components of the engine, suspension, and transmission.

Undercarriage installation includes the following procedures: 1. Installation of the axle shafts (Figure 8-42). 2. Installation of the transmission and engine braces. 3. Connection of the exhaust system to the exhaust manifold. 4. Installation of any splash shields and/or heat shields. 5. Connection of clutch and shift lever linkages, and adjustment as needed. 6. Connection of any transmission cooling lines. 7. Connection of all wiring harnesses that are routed to the underside of the engine. 8. Installation of the tires and wheels, being sure to torque the lug nuts to the specified value. 9. Connection of the fuel delivery system.

Caution Make sure the engine hoist is capable of lifting the weight of the engine to a height sufficient to clear the engine compartment.

After the undercarriage installation is completed, the vehicle can be lowered so upper engine connections can be made. Following are common procedures required at the upper engine:

1. Connection of the fuel lines to the fuel rail or carburetor. 2. Connection of the heater hoses. 3. Installation of engine ground straps. 4. Connection of all engine electrical connectors. 5. Connection of all vacuum and fluid hoses. 6. Connection of the throttle linkage and adjustment as needed. 7. Installation of the radiator and cooling fans. This may also include connection of the transmission cooling lines (if equipped). 8. Installation of the upper and lower radiator hoses. 9. Installation of the battery tray. 10. Installation of the air cleaner, air intake ducts, and vacuum hoses.

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11. Installation and connection of any control modules. 12. Installation of the battery. Before making connections, make sure all wires are properly connected. Connect the battery, positive terminal first and then the negative terminal. 13. Fill the radiator. 14. Fill the crankcase with the proper oil type and quantity. 15. Fill the brake master cylinder or clutch cylinder as needed. 16. Fill the transmission with the proper fluid. 17. Follow the service manual procedures to fill the air-conditioning compressor with proper oil and amount; then connect the hoses. SERVICE TIP  A technician must be EPA Section 609 certified for refrigerant recovery and recycling to recover and recharge the air-conditioning system. WARNING  Never wear jewelry when working around the vehicle. Gold, silver, and copper are excellent conductors of electricity. Your body is also a conductor of electricity. If the jewelry makes contact with a current-carrying wire or terminal, severe injury may result. Jewelry may also become caught on objects or in fans and other rotating parts.

Rear-Wheel-Drive Vehicles On most rear-wheel-drive vehicles, it is possible to install the engine through the hood opening. Begin by attaching the engine lifting fixture to the engine. The following procedure is typical of most engine installations: WARNING  Do not lift the engine by the intake manifold. This action may cause the intake manifold or retaining bolts to break, allowing the engine to drop suddenly, resulting in technician injury.

Caution Make sure to install the proper refrigerant oil into the system. Oil used in R-12, R-134a, and R-1234yf systems is not interchangeable.

1. Lift the engine high enough to clear the vehicle, and center it over the motor mount towers. If the transmission is attached, it will have to be tipped to clear the bulkhead and lowered slowly to center it. 2. Slowly lower the engine until the engine settles into the front mounts. 3. Use a transmission jack to support the transmission. Locate the jack in an area that will not interfere with installation of the rear motor mount. 4. Secure the front motor mounts and cross members. 5. Install the rear motor mount and cross member. Complete under vehicle installation by raising the vehicle on the hoist. Install transmission and engine braces, and connect the exhaust system to the exhaust manifold. Make sure to install any splash shields and/or heat shields. Connect the clutch and shift lever linkages, and adjust as needed. Many clutch assemblies use hydraulic cylinders to actuate the clutch. These require the air to be bled for proper operation. On automatic transmissions, connect the cooling lines. In addition, connect all wiring harnesses that are routed to the underside of the engine. Finally, connect the drive shaft, using the marks made during removal to align it properly. Lower the vehicle, and complete the upper engine connections. These may include the following: 1. Connecting the fuel lines. 2. Connecting the heater hoses. 3. Installing engine ground straps.

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4. Connecting all engine electrical connectors. 5. Connecting all vacuum and fluid hoses. 6. Connecting and adjusting the throttle linkage. 7. Installing the radiator and cooling fans. Connecting the transmission cooling lines (if equipped). 8. Installing the upper and lower radiator hoses. 9. Installing the battery tray. 10. Installing the air cleaner, air intake ducts, and vacuum hoses. 11. Installing and connecting any control modules. Installation is complete after the following procedures are performed: 1. Install the battery. Before making connections, make sure all wires are properly connected. Connect the battery, positive terminal first and then the negative terminal. 2. Fill the radiator. 3. Fill the crankcase with the proper oil type and quantity. 4. Fill the brake master cylinder or clutch cylinder as needed. 5. Fill the transmission with the proper fluid. 6. Install and align the hood. 7. Follow the service manual procedure to fill the air-conditioning compressor with oil.

SERVICE TIP  It is a good idea for easier access to leave the hood off until the engine has been run and everything double-checked.

ENGINE START-UP AND BREAK-IN The first 20 minutes of an engine’s life is a critical time. Lubrication must be flawless, and coolant must be circulated efficiently. Worn parts have already lost their high spots and sharp edges, but new components must wear in; they need proper lubrication to avoid excessive scuffing. The increased friction of new parts creates higher engine temperatures that only a fully functional cooling system can control. The rings begin to break into the cylinder walls and develop a seal. The whole valvetrain must be properly adjusted and functional to allow the valves to wear into their seats. The bearings will be conforming to the shape of the journals. During the first couple of thousand miles of operation, the bearings will embed some fine metal particles into them as the sharp rings scrape the cylinder walls to seat. The new lifters and perhaps new camshaft will also experience some critical mating during the first half hour of operation. If you are installing a crate engine, you may receive specific instructions to follow. Manufacturers may also include guidelines about engine start-up and break-in. Camshaft manufacturers may include additional instructions to follow for the break-in process. This section will give generalized advice that should apply to start-up and break-in for most new or freshly rebuilt engines. We also discuss the important conversation you should have with the customer before handing over the keys.

CUSTOMER CARE  The process you use to break in a new engine can affect engine performance and oil consumption during the first few thousand miles.

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Start-Up and Initial Break-In The initial start-up and the first 20 minutes of operation are critical to the health of the new or rebuilt engine. Before starting the engine, double-check the fluids to be sure they are at the proper level; low coolant could cause engine overheating during the first 20 minutes of operation. A low oil level could be disastrous. The lubrication system should be primed before the engine actually runs, if possible, or the first minutes of operation could cause undue wear on new components. You should be prepared to evaluate the engine operation and sealing during its initial break-in period.

Priming the Lubrication System If the oil pump is driven by the crankshaft, you will not be able to physically rotate the pump effectively to prime the system. It is best to use an oil priming tool that will deliver oil under pressure to the engine through an adaptor on the oil filter housing or in the oil pressure sending unit bore. Some parts stores carry pressurized aerosol priming oil cans that can spray oil throughout the engine via the oil sending unit port. On an older engine that drives the oil pump through the distributor shaft, you can physically rotate the shaft to prime the lubrication system. You should already have an oil pressure gauge installed on the engine. If not, remove the oil pressure switch and install a gauge now. What you want to do is rotate the oil pump until some oil pressure is seen on the gauge. You will not meet normal oil pressure specifications, because you will not be able to spin the pump at a high enough rpm. You will know that oil has reached all areas of the engine. To rotate the pump, use a special drive tool to attach to the drive point of the pump. You may be able to use a 1/4-in. drive extension, a special tool with the correct flat drive on the end, or an old distributor drive shaft from another engine. Use a drill or a speed handle to rotate the pump until you can feel significant resistance. Continue rotating the pump for a minute or so to be sure that oil has reached the top of the engine. If priming the system is not an option, then disable the ignition and fuel systems, remove the spark plugs, and crank the engine until proper oil has been reached; however, do not do this for more than about 30 seconds at a time to keep from overheating the starter.

Starting the Engine

Caution Cranking the engine for extended periods can permanently damage or destroy a starter motor.

Set wheel chocks before and after a wheel. If the shift linkage has been disturbed and is not properly adjusted, the engine could start in gear and lurch forward. Set the parking brake as an added precaution. Install appropriate exhaust extraction equipment; the engine will smoke while it runs for the first several minutes. Recheck the oil and coolant levels; you should be positive that the engine will have adequate lubrication and cooling. Crank the engine over until it starts or for 30 seconds maximum. If everything in and on the engine is properly connected and adjusted, it should start within two 30-second cycles of the starter. If the engine does not start, take another look at electrical connectors and vacuum lines. Check the engine to be sure it is getting proper spark and fuel. Once the engine starts, it is important to hold the rpm to between 1,500 rpm and 2,000 rpm for the first 20 minutes of operation. Block the throttle open or use an adjusting rod on the accelerator pedal so you can make other checks while the engine runs. The increased engine rpm ensures that good oil pressure will lubricate all areas of the engine adequately. It also ensures that the cylinder walls receive generous splash flow. Make sure that the oil pressure is within specifications. The new rings will need good lubrication to prevent scuffing as they break in to the cylinders. A new camshaft and lifters will endure a lot of friction as they wear in together. Engine bearings will conform to their journals during the first minutes of operation. These areas of increased friction and others require the higher oil pressure and flow delivered at the increased engine rpm. Do not let the engine idle.

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Monitor the oil pressure, and be sure it stays within the specified psi. After a few minutes of operation, top off the coolant level once it has circulated throughout the engine. Replace the reservoir or radiator cap before the thermostat opens. Check the radiator inlet hose as the engine heats up; it should get hot and full as the engine warms up to temperature. If problems occur with oil pressure or cooling, or if you hear unusual noises, shut the engine down and investigate. Prevent extensive engine damage that could occur if you continue to run the engine while obvious problems exist. While the engine is running at 1,500 rpm to 2,000 rpm, check the engine for leaks. Raise the vehicle, and be sure that no seals, gaskets, or plugs are leaking. If you find leakage, stop the engine and repair the leaks now before damage occurs. It may be frustrating to go backward, but it is a lot better than having to redo major engine work. Listen for unusual noises all over the engine. Use a stethoscope, if needed, to isolate rattles or belt or bearing issues. Make sure that the engine is running on all its cylinders. The engine should look steady and sound smooth under the hood. The exhaust should have regular pulses of exhaust. Listen for vacuum or compression leaks, and correct if needed. Continually check the engine oil pressure and cooling system. Verify that the cooling fan comes on when the engine reaches the prescribed temperature. Use a pyrometer for the best accuracy and definitely if there is no coolant temperature gauge to monitor the engine temperature. Check for proper charging system operation by placing the leads of your voltmeter across the positive and negative posts of the battery. If the generator, voltage regulator, and wiring are all good, you should read between 13.5 and 15.0 volts. After 20 minutes of high-rpm operation, return the engine to its normal idle speed. Set the ignition timing as specified if applicable. Shut the engine down, and remove the oil pressure gauge. Install the oil pressure switch, and verify proper operation. The light must come on with the key in the RUN position; it should go out promptly after engine start-up. Make sure there is no oil leakage by the switch. Check all fluid levels before going on a road test.

Road Test Prepare yourself for a 15- to 20-minute road test. Turn the radio off so you can listen closely for rattles, knocks, or squealing. If any abnormal noises occur, make a mental note to repair the associated problem upon return. On modern engines, a knock sensor can pick up vibration from a rattle or knocking and the powertrain control module (PCM) will retard the timing and reduce power. If a rattle or knock is left alone, engine performance will suffer. If you can hear a noise, the customer will also likely pick it up. Figure out the cause, and repair it when you return to the shop. Pull over and stop the engine if a serious knocking noise occurs or if the oil light comes on. Attempting to limp the vehicle back to the shop could destroy your work. During the road test, you need to begin the process of breaking in the rings. Some ring manufacturers say this is no longer necessary, but it is still a generally recommended procedure. Run the vehicle on the highway or open road. Accelerate to 50 mph (as the speed limit allows), and allow engine braking to bring the speed back down to 30 mph. Accelerate aggressively but not to wide-open throttle. You should stay below 75 percent of maximum engine load while still pushing the engine close to that threshold. Repeat this cycle a dozen times. The acceleration will help the rings seal with good pressure around them. The high vacuum during deceleration helps keep the cylinder walls and rings well lubed as the rings break in. Do not over rev the engine or drive at excessive speeds. The smoking from the exhaust should noticeably diminish after this process, although a little blue smoke is still normal. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Final Checks After Break-In After your road test, repair any concerns noticed while you were driving. If you noticed a problem with the brakes, suspension, or exhaust system, mark your observations on the repair order so you can communicate these to the customer when he or she picks up his vehicle. If the check engine or MIL light came on during your road test, extract the diagnostic trouble code (DTC) from the PCM. If the code relates to a component such as the throttle position sensor or manifold absolute pressure sensor, check the wiring connections and vacuum supply to the part as applicable. Next, diagnose the fault using the manufacturer’s procedure. Give a final check to all the fluid levels. Take the time to put the vehicle back up on the lift and make sure there are no leaks from the engine. Repair any faults now, before the customer can notice them and return angrily to you. A small oil leak could lead to serious engine damage once the customer is driving the vehicle. Take one last look under the hood at wires, hoses, vacuum lines, fuel lines, and belts. Clean the steering wheel, seat, and fenders. Check the seat for any spots, and use an appropriate cleaner if needed. Put a fresh floor mat into the vehicle. Set the radio station presets to the channels you recorded earlier or to a variety of channels with good reception. Adjust the clock to the proper time. Set the trip odometer to zero so the customer can keep an eye on the mileage. Let the customer know that the battery had been disconnected. Explain that you set the clock and some radio stations but that those and seating memory position presets or other memory functions may not be set exactly as they had been. Tell them that you set the trip odometer to zero so they will be aware of when they should return for the 500-mile service. Explain the importance of returning for this oil change and checkup. Before handing over the keys, explain how the customer should drive the vehicle for the first few hours and then for the next 2,000 miles. In the short term, the customer should avoid maximum engine load or extensive idling. The more they vary the engine speed, the better it is for the rings. Ask the customer to idle the engine for 30 seconds before shutting the engine down after a hard drive. During the first 2,000 miles of operation, the customer should avoid over-revving the engine or driving at excessive speeds. They can drive aggressively but not to the point of abuse. Make sure the customer is aware that the rings may not fully seat for a few thousand miles. This can cause increased oil consumption, which is normal. Ask them to check and refill the oil and other fluids at every fuel fill while the engine is still breaking in. If they keep notes on the amount of oil they have to add, you will be able to gauge whether a problem is indicated. A final step in excellent customer service is to call the customer after a week to make sure the engine is running properly and that they have no concerns. Remind them of the 500-mile service and its importance to the longevity of the engine. Thank them for their business and let them know you will be looking forward to checking out their vehicle soon. This follow-up call can be an important one. It is hard to overcome the negative statements an unhappy customer might make to others in the community. A satisfied customer is the best advertisement you can get for your shop; take the time to be sure you have done the excellent work you have been trained to perform.

Five-Hundred-Mile Service After 500 miles of operation on a new or rebuilt engine, you should ask the customer to return for a service. Most shops will bill this into the engine overhaul charges so that it appears to be a “free” service to the customer. They are less likely to return if they have to lay out more money shortly after paying the large bill for major engine work. The service work should include an oil change. The oil becomes contaminated quickly with small metal particles as new engine components wear in. It is occasionally Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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recommended to retorque the intake manifold. Cylinder head shifting can affect manifold bolt tightness. Check the adjustment of solid lifters after the valves have had time to wear into their freshly ground or new seats. Verify that the engine is running and idling properly. Finally, road test the vehicle, and be sure that it is performing as it should. Take any measures needed to avoid a customer comeback. Repair any concerns that could be related to your engine work. Make a note of other problems, and discuss them with the customer. CUSTOMER CARE  It is best if you can speak directly with the customer when she or he comes to pick up her or his vehicle after major work. Be sure you are presentable and prepared to explain the work you have completed. Describe the problems you found and how you corrected them to ensure proper engine operation. Let the customer know that you have road tested the vehicle and that you know the engine is running properly. If you noticed any unrelated concerns, describe those to the customer so she or he is not surprised. If an axle boot is cracked or the muffler is leaking, let her or him know before she or he drives the vehicle. The customer will be more aware of noises and faults after a major service. Be prepared with a rough estimate of what the additional work would cost.

CASE STUDY On my very first engine overhaul, I failed to properly tighten the flywheel bolts. When I started the engine up, it had a serious knock. Luckily, the flywheel bolts were accessible through a cover, and I checked them before disassembling anything on the engine. Once they were properly torqued, the engine ran well and lasted a good long time for the customer. I never made that mistake again!

ASE-STYLE REVIEW QUESTIONS 1. Preparing the engine for removal is being discussed. Technician A says that you should read through the service procedure for the specific vehicle before beginning. Technician B says that the air-conditioning refrigerant should be vented to the atmosphere. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says to disconnect the positive ­battery cable first and then the negative cable. Technician B says to disconnect the negative ­battery cable first. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says that when removing the engine from a front-wheel-drive vehicle, you should first remove the differential. Technician B says that when removing an engine from a front-wheel-drive vehicle, it may be ­necessary to remove some steering and ­suspension components. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

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4. Technician A says that a front-wheel-drive engine may be removed from the top through the hood opening. Technician B says that the transaxle may have to be removed with the engine on a front-wheeldrive vehicle. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that you should use a special cradle to support the engine when it is removed from the bottom of the vehicle. Technician B says that you should remove the heavy accessories from the engine while it is on the hoist before mounting the engine on the stand. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 6. Technician A says that you often need to remove the radiator before removing the engine. Technician B says to drain the coolant from the engine block as well as from the radiator. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 7. Technician A says that when you are installing a crate engine, you will usually install a new water pump if one does not come with the engine. Technician B says that you will need to swap ­components such as sensors and actuators. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

8. Technician A says that a new or freshly rebuilt engine will run at higher engine temperatures during the break-in period. Technician B says that you should check oil ­pressure during the break-in period. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. Technician A says that during the first road test, you should accelerate and decelerate to full ­throttle several times to maximize oil pressure. Technician B says that after the road test, you should put the vehicle back up on the lift and make a final check for fluid leaks. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that any engine stand can hold engines that are eight cylinders or less. Technician B says that the attaching bolts must be threaded in at least as much as one and a half times the diameter of the bolts. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

ASE CHALLENGE QUESTIONS 1. Technician A says that an ECR valve should be thoroughly cleaned of RTV and fuel before reinstallation. Technician B says that the purge solenoid admits fuel vapors from the fuel tank into the intake manifold. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

2. Technician A says that you can remove the valve stem from the Schrader valve to drain the fuel from the fuel rail. Technician B says to install a pressure gauge to drain the fuel from the fuel rail. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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3. Technician A says to remove all the engine accessories before mounting the engine on the stand. Technician B says to place the crate engine next to the old engine to help you transfer all the accessories to the proper location. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. Technician A says that it is illegal to discharge most refrigerants into the atmosphere. Technician B says that you must be certified to operate air-conditioning recover/recycle/recharge equipment. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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5. Technician A says to let the engine idle for the first 15 minutes of operation after a rebuilt engine is installed. Technician B says that the oil should be changed after 500 miles of service on the rebuilt engine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Removal, Engine Swap, and Engine Installation

Name ______________________________________

Date __________________

373

JOB SHEET

50

ENGINE REMOVAL FWD Upon completion of this job sheet, you should be able to properly prepare and remove the engine from a vehicle. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.10. Remove and reinstall engine in an OBD II or newer vehicle; reconnect all attaching components and restore the vehicle to running condition. Tools and Materials • Engine lift • Engine stand • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will assign you (or your group) to a vehicle that needs to have its engine removed. Using the proper service manual, you will identify and perform the required steps to remove the engine. 1. Is the vehicle FWD? According to the service manual, does the engine come out from the top or the bottom?

h Yes  h No h Top h Bottom

2. Following all safety cautions and warnings, clean the engine and compartment.

h

3. On a separate sheet of paper, make a list of any special tools and equipment that are required to remove the engine. After making the list, gather the tools and organize them in your area.

h

4. Center the vehicle over the frame contact hoist.

h

5. Disconnect and remove the battery.

h

6. Lift the vehicle and drain all necessary fluids.

h

7. Is the transmission coming out with the engine?

h Yes  h No

8. Make a list of all the components that can be removed easily while the vehicle is on the hoist. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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Task Completed 9. Describe the method you will be using to ensure correct electrical and vacuum line connections are made when the engine is reinstalled. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Perform all steps necessary to prepare the bottom of the vehicle for engine removal.

h

11. Lower the vehicle, and perform all steps needed to prepare the top of the engine for removal.

h

12. List the components that can be removed as units from the engine block. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 13. Following the service manual procedure, remove the engine.

h

14. Once the engine is removed, attach it to an engine stand.

h

15. When attaching the engine to the stand, what is the minimum depth the bolts must thread into the block?

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Engine Removal, Engine Swap, and Engine Installation

Name ______________________________________

Date __________________

375

JOB SHEET

51

ENGINE REMOVAL RWD Upon completion of this job sheet, you should be able to properly prepare and remove the engine from a vehicle. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.10. Remove and reinstall engine in an OBD II or newer vehicle; reconnect all attaching components and restore the vehicle to running condition. Tools and Materials • Engine lift • Engine stand • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will assign you (or your group) to a vehicle that needs to have its engine removed. Using the proper service manual, you will identify and perform the required steps to remove the engine. 1. Is the vehicle RWD? According to the service manual, does the engine come out from the top or the bottom?

h Yes  h No h Top h Bottom

2. Following all safety cautions and warnings, clean the engine and compartment.

h

3. On a separate sheet of paper, make a list of any special tools and equipment that are required to remove the engine. After making the list, gather the tools and organize them in your area.

h

4. Center the vehicle over the frame contact hoist.

h

5. Disconnect and remove the battery.

h

6. Lift the vehicle and drain all necessary fluids.

h

7. Is the transmission coming out with the engine?

h Yes  h No

8. Make a list of all the components that can be removed easily while the vehicle is on the hoist. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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Task Completed 9. Describe the method you will be using to ensure correct electrical and vacuum line connections are made when the engine is reinstalled. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Perform all steps necessary to prepare the bottom of the vehicle for engine removal.

h

11. Lower the vehicle and perform all steps needed to prepare upper engine for removal.

h

12. List the components that can be removed as units from the engine block. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 13. Following the service manual procedure, remove the engine.

h

14. Once the engine is removed, attach it to an engine stand.

h

15. When attaching the engine to the stand, what is the minimum depth the bolts must thread into the block? _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Engine Removal, Engine Swap, and Engine Installation

Name ______________________________________

Date __________________

377

JOB SHEET

52

ENGINE INSTALLATION Upon completion of this job sheet, you should be able to properly prepare and install the engine into a vehicle. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.10. Remove and reinstall engine in an OBD II or newer vehicle; reconnect all attaching components and restore the vehicle to running condition. Tools and Materials • Engine lift • Technician’s tool set • Vehicle lift Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will assign you (or your group) to a vehicle that needs to have its engine removed. Using the proper service manual, you will identify and perform the required steps to remove the engine. 1. Is the vehicle FWD or RWD? If FWD, according to the service manual, does the engine get installed from the top or the bottom?

h FWD h RWD h Top h Bottom

2. Prepare the engine compartment for reinstallation by tying back any hoses, lines, or components that may be in the way.

h

3. If necessary, be sure that the suspension components are not going to block engine installation.

h

4. Make sure that the transmission is properly mounted and fastened to the engine if it was removed with the engine.

h

5. Center the vehicle over the frame hoist.

h

6. If the engine is being installed from the bottom, raise the vehicle on the lift. Center the engine under the vehicle, and slowly lower the engine into alignment with the mounts. Reattach the engine mounts, and secure the components required from underneath the vehicle. Make a list of components that need to be reinstalled from underneath the vehicle. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

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Task Completed 7. If the engine is being installed from the top, center the engine crane over the engine compartment. Slowly lower the engine into alignment with the engine mounts, and secure the engine mounts. Raise the vehicle, and describe the components that need to be reinstalled from underneath the vehicle. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Lower the vehicle, and attach all the hoses, lines, electrical connectors, and components that need to be reattached. Describe the process and components. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 9. Double-check your work so far. Then fill the engine and other components with fluids. Describe what fluids need to be filled. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Install an oil pressure gauge into the system so you can monitor oil pressure at start-up.

h

11. Start the engine, and follow the break-in procedures. Describe the procedures and your results here. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Removal, Engine Swap, and Engine Installation

Name ______________________________________

Date __________________

379

JOB SHEET

53

INSPECT, REMOVE, AND REPLACE ENGINE MOUNTS Upon completion of this job sheet, you should be able to properly inspect, remove, and replace engine mounts. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.8.

Inspect, remove, and replace engine mounts.

Tools and Materials • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle and engine package. Write down the information, and then perform the following tasks: 1. Looking under the hood and using the service manual as a reference, describe what type of motor mounts this vehicle has. _________________________________________________________________________ _________________________________________________________________________ 2. While using the service manual, check for any related TSBs.

h

3. You will need a partner to help you test the engine mounts. Open the hood, and locate the engine mounts. Have your partner start the engine, let it idle, hold the brake, and shift into gear (automatic transmission only—if using a manual transmission, place the car 1 ft off the ground on a hoist and have your assistant release the clutch while in first gear and idling). The engine should have moved when the transmission was engaged, but very little. Did the engine move? _________________________________________________________________________ 4. Turn the engine off. If the mounts are a rubber bushing style, use a pry bar to attempt to move the mounts and engine. Some slight movement is allowed. What did you find? _________________________________________________________________________ 5. If the mounts are hydraulic, inspect them for leaks. What did you find? ________________________________________________________ 6. Based on your inspection, what services would you recommend?__________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 9

CYLINDER HEAD DISASSEMBLY, INSPECTION, AND SERVICE

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■

■■

■■

■■ ■■

■■

How to remove a cylinder head from an engine. How to properly disassemble a cylinder head and prepare it for inspection and cleaning. How to perform a complete visual inspection of the valve and determine any failures or damage. How to properly determine wear of the valves by use of measuring instruments and by comparing results with specifications. How to inspect the cylinder head casting for cracks. How to determine the amount of mating surface warpage and recommend needed repairs. How to measure valve guide wear, clearance, and taper, and determine needed repairs.

■■

■■ ■■

■■ ■■ ■■ ■■ ■■

How to perform a complete visual inspection of the valve seats and properly measure valve seat width and runout. How to straighten aluminum cylinder heads.

Basic Tools Basic mechanic’s tool set Service manual

How to correct camshaft bearing bore alignment in an overhead camshaft (OHC) cylinder head. How to repair or replace worn valve guides. How to replace integral and insert valve seats. How to grind valves and obtain correct contact pattern. How to recondition valve faces and stem tips. How to identify proper valve face-toseat contact patterns.

Terms To Know Core plugs False guide Gallery plugs Interference angle

Liners Prussian blue Seat concentricity Throating

Topping Valve stem height

INTRODUCTION The cylinder head can be removed with the engine installed in the vehicle or as part of engine disassembly on an engine stand. With the cylinder head removed from the engine block, it is ready to be disassembled, cleaned, and completely inspected. The cylinder head should be checked for cracks after it is cleaned. Work performed on a cracked cylinder head would be wasted. Disassembly generally includes removal of the rocker arms, valve springs, valves, core plugs, and oil gallery plugs. It is important for today’s technician to properly inspect the cylinder head and its components to determine the presence of defects. Just as important, the cause of the failure should be identified. This chapter covers

Core plugs are used to cap the holes used to create hollow passages for coolant during the foundering process. Gallery plugs are used to cap the drilled oil passages in the cylinder head or engine block.

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typical cylinder head disassembly procedures and inspection. Keep track of the ­measurements obtained and the results of the inspections on the work order or in a notebook for future reference. Once the technician has determined the type of machine work required to restore the cylinder head, the actual work is the next step. Using the information gathered during the inspection process, the technician should have a good idea of how much machining will be required for each operation. It is important to perform the different machining and reconditioning operations in a logical order. This will prevent having to repeat operations. The valve faces and seats are usually reconditioned as a matter of common practice whenever the cylinder heads are disassembled. This chapter provides general procedures for reconditioning the cylinder head. In addition, this chapter discusses other major cylinder head reconditioning operations, including straightening aluminum cylinder heads, valve guide repair, reconditioning valve seats, grinding valves, and reconditioning cast rocker arms. The diversity of the different types of equipment available to perform cylinder head reconditioning operations makes it impossible to cover each procedure with each machine. The general procedures are provided in this text. Always refer to the equipment manufacturer’s instructions. If you are not familiar with the equipment, seek instruction before attempting to operate it.

Cylinder Head Removal Cylinder head removal can be performed as an in-vehicle service if a total engine rebuild is not necessary. Follow the manufacturer’s service information for cylinder head removal. It will offer the most accurate instructions for proper service. Our discussions are general and are to give you a sense of the procedure. They are not a replacement for specific service instructions. The removal procedure will vary depending on whether the engine is an OHC (overhead cam) or OHV (overhead valve) engine. Regardless of the design, some typical precautions should be observed. These include the following: 1. Do not loosen the intake manifold or head bolts when the engine is still warm. These components and the block should cool together to prevent warpage. 2. When removing the intake manifold bolts, reverse the tightening sequence as described in the service manual. 3. When removing the cylinder heads, loosen the head bolts in the reverse of the tightening sequence listed in the service manual. Loosen all the bolts first, and then go back and remove them.

OHV Engine Head Removal To remove the cylinder heads from an OHV engine, begin by removing the valve covers (Figure 9-1). If the engine is in the vehicle, you may need to remove electrical connectors, vacuum lines, the throttle cable, and various brackets and components to gain access to the covers. Mark these lines, connectors, and brackets for reference during reassembly. Use special care when removing plastic, aluminum, and magnesium valve covers. They will not bend; if you crack them, they must be replaced. Tin and stamped steel valve covers are a little more forgiving. If the engine is equipped with a distributor, it may need to be removed. Prior to removing it, make an index mark to aid in proper installation. Remove the intake ductwork and other components that will hinder the removal of the intake manifold. When removing the intake manifold, remove it in as much of an assembly as possible (Figure 9-2). The intake manifold can usually be removed with the injectors, fuel rail, and throttle body still attached. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Figure 9-1  In this case, you’ll have to remove the ignition cassette to gain access to the valve cover bolts.

Fuel rail

Throttle body

Injectors

Figure 9-2  Remove the intake manifold with the fuel rail and injectors attached.

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Figure 9-3  Soak the rusty exhaust manifold nuts with penetrating oil or use heat to remove them.

Next, remove the exhaust manifold from the cylinder head. In some areas of North America the exhaust studs and nuts may be quite rusty. You will usually replace the studs, but it is easier to remove them if they are not broken. It is good practice to spray these fasteners with penetrating oil and to allow them to soak a few minutes before removing them (Figure 9-3). In some cases, you will need to use some heat on the nuts before attempting to loosen them. Remove the rocker arm assemblies and pushrods. The method of removing the rocker arms depends on the mounting design. If the rocker arms are located on a single shaft, remove the fasteners that attach the shaft to the cylinder head. If the rocker arms are stud mounted or pedestal mounted, remove each one individually by removing the adjusting nut. If the rocker arms and push rods are going to be reused, it is a good practice to mark or store them in their original positions to ensure they are installed in the proper positions during reassembly. Next, remove the cylinder head bolts in reverse order of the tightening sequence. Break each bolt loose first; then go back and remove them. Pay attention to the sizes of the bolts as you remove them. Mark the bolts to identify their locations for reassembly (Figure 9-4).

Figure 9-4  Whether this is your first time rebuilding an engine or not, keep the bolts organized. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service Cylinder head gasket

8–9 mm

Dowel

Cylinder block

Figure 9-5  Do not attempt to slide the heads off, lift straight up otherwise you may damage the dowel pins or the head.

The cylinder head should now be ready for removal. It may be necessary to pry the cylinder head to break it loose. Make sure to pry in a location that will not damage the sealing surfaces. Do not use excessive force to pry the cylinder head loose. If it does not come off, make sure all of the bolts have been removed. On engines that use wet liners, leave the center bolt loose in the head and place a 2 3 4-inch block of wood against the cylinder head. Hit the wood sharply with a hammer to rotate the cylinder head. This will break the sleeves loose from the head and prevent them from being lifted out of the block as the head is lifted. SERVICE TIP  Never attempt to “slide” the head off the cylinder block. You may damage the head or block by moving the dowel pins in the block (Figure 9-5).

OHC Engine Head Removal Begin cylinder head removal by removing the valve cover. This may require the removal of several accessory items first. Next, remove the intake manifold (Figure 9-6). Then remove the exhaust manifold and gasket from the cylinder head (Figure 9-7). On an overhead camshaft engine, you will have to disturb the timing mechanism, either a timing chain or a timing belt. In many cases, there is a special tool that bolts to the camshaft sprockets, or in between the chain on a dual overhead camshaft engine, to hold the timing chain in place for cylinder head service. This tool prevents you from having to disassemble the front cover and access the tensioner. It will hold the chain in place while you remove the cylinder head. Follow the service manual instructions to install the tool before removing the camshaft or sprockets. If you do need to remove the belt or chain, be sure to rotate the engine to TDC number 1 and note the timing marks on the camshaft sprocket. If the engine is equipped with a variable valvetrain, you will have to use special tools to remove the servo and camshaft. These are explained in the manufacturer’s service manual. In some cases, you will need to remove the rocker arm shaft assemblies to gain access to the cylinder head bolts. Be sure to mark the rocker arms so they can be returned to their original positions on the camshaft. Other engine designs necessitate the removal of the camshaft. Some camshafts slide out of the bearing supports; others have split caps that allow the camshaft to be lifted from the cylinder head (Figure 9-8). Note the markings on the caps before disassembly. It is critical that the caps be returned to the same location Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 9 Intake manifold

Gasket Exhaust manifold

Upper cover Gasket

Bracket Cylinder head

Figure 9-6  Removing the intake manifold from an OHC engine.

Heat shield

Figure 9-7  Removing the exhaust manifold, shields, and brackets.

Camshaft bearing cap

Cylinder head

Camshaft

Figure 9-8  Some OHC engines use split camshaft bearings. Note the markings, and remove the caps to remove the camshaft from the engine. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

387

and installed in the same direction when reassembling. When removing the caps, follow the sequence in the service manual to prevent warping or breaking of the camshaft or damage to the threads in the cylinder head. As the camshaft is removed, mark or organize the followers to identify their original positions. There may be adjusting shims with each follower; it is important to keep them with their respective valve and follower assemblies.

DISASSEMBLING THE CYLINDER HEAD The cylinder head is attached to the block above the cylinder bores and is usually constructed of cast iron or aluminum. Disassembling the cylinder head usually begins with cleaning it with mild solution in a parts washer or by using a steam cleaner. Sludge can build up around the rocker arms and valve spring areas. Excessive sludge may indicate that the engine was neglected. This may include improper oil change intervals or not allowing the engine to warm properly before driving short distances. Removing this sludge will make the task of cylinder head disassembly easier and safer. However, before cleaning the head, inspect the combustion chamber. The type, color, and quantity of carbon buildup can provide hints to identify problem areas.

Classroom Manual Chapter 9, page 177

Special Tools Parts cleaner

CUSTOMER CARE  If excessive sludge is found throughout the cylinder head and crankcase, tactfully explain to the customer the need to change the engine oil at the mileage interval recommended by the vehicle manufacturer.

Normal carbon buildup is a light layer evenly covering the combustion chamber. If the carbon is thick and black in color, this indicates excessive oil induction into the combustion chamber. Oil induction is also identifiable by an oily residue on the carbon. This could be the result of worn valve stem seals, valve guides, or rings. Dry, black, ash-type deposits indicate a rich air-fuel mixture or ignition misfire. Some common causes include a ruptured fuel-pressure regulator, excessive fuel pressure, leaking injectors, or faulty spark plug cables, coils, or spark plugs. If the combustion chamber is clean and the metal is shiny, engine coolant may have leaked into it (Figure 9-9). This can be caused by a damaged head gasket, cracked cylinder head, cracked engine block, or blown intake gasket.

See Chapter 4 for information on removing core plugs. A core plug may be called a frost plug. If antifreeze protection is inadequate and coolant freezes in the cylinder head, the core plugs are usually pushed out of the head.

Figure 9-9  The number 1 piston is clean from a blown head gasket, allowing ­coolant into the cylinder. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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After the initial inspection of the cylinder head is complete, the head should be cleaned. Before cleaning the cylinder head, remove the core and gallery plugs. Remove carbon deposits from the combustion chambers with a scraper or wire wheel; then clean the cylinder head in a parts cleaner or use a steam cleaner. This cleaning will make cylinder head inspection easier and disassembly safer. It will be necessary to clean the cylinder head again after the valves and valvetrain components are removed. Once the initial cleaning is complete, inspect the cylinder head for cracks and other obvious damage. If the engine has been overheated, the cylinder head should be checked for cracks using magnaflux if it is cast iron or through pressure testing or fluorescent dye if it is aluminum. Aluminum heads should always be checked for cracks. If the cylinder head assembly has excessive damage, it may be more cost-efficient to replace it instead of repairing it. If the cylinder head passes this preliminary inspection, it is ready for disassembly. The rocker arms usually must be removed before the valves can be accessed for removal. Some OHC cylinder head designs have the camshaft running a follower directly on the valve, while others use rocker arms. Rocker shafts are removed as an assembly by removing the shaft retainer bolts (Figure 9-10). If the rocker arms are fitted under the camshaft, it may be necessary to remove them by prying against the spring retainer and sliding the rocker arm out.

Valve Removal Before beginning the task of removing the valves from the cylinder head, review the ­following safety concerns:

Special Tools Valve spring compressor Soft-faced hammer Pencil magnet Organizing board

1. Check the condition of the valve spring compressor before using it. If the tool is worn or damaged, do not use it. 2. Always wear safety glasses when removing the valve springs. When removing the keepers, the valve springs must be compressed. If the spring comes loose, both the keepers and the spring may be propelled at a high rate of speed and force. 3. When removing the valve springs, do not stand in front of the springs. Turn the heads so you are facing the combustion chamber and the springs are facing away from you. 4. Do not compress the valve spring more than needed to remove the keepers. Overcompressing the spring may result in damage to the compressor and cause the spring to come loose (Figure 9-11).

Shaft retainer bolts

Figure 9-10  Remove the rocker shaft retainer bolts to remove the rocker arm shaft.

Figure 9-11  Use a valve spring compressor to compress the spring and remove the keepers.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Valve stem installed height

Spring seat

Figure 9-12  Measuring valve stem tip height.

Figure 9-13  Valve stem height gauge.

Before removing the valves from the head, measure valve stem height. After the springs are removed, measure the height of the valve stem tip from the head casting (Figure 9-12). This can be done using calipers or by special tools designed for this function (Figure 9-13). Record the measurements for reference when performing valve reconditioning. When disassembling the cylinder head, consider the following: SERVICE TIP  A simple cylinder head holding fixture can be made using two tapered punches welded to a piece of steel.

1. Organize the components so their original positions in the head are maintained. This can be done using a board with holes drilled in it to hold the valves, valve springs, and rocker arms. 2. When handling OHC cylinder heads, remember some of the valves will be held open by the camshaft. Do not set the head down on the combustion chamber side, or damage to the valves may result. Mounting the head on head stands will prevent this damage, and make the disassembly procedure easier (Figure 9-14). 3. The valve retainers may be stuck to the keepers. Break the varnish loose before attempting to compress the spring by gently striking the retainer with a soft-faced hammer with an old piston pin (or small piece of pipe).

Head stands

Figure 9-14  Use head stands to hold the head up off the bench. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 9-15  Remove any tip “mushrooming” before removing the valve from the guide.

4. Measure stem tip height prior to removing the valve. After the valve springs are removed, use vernier calipers or a special valve stem tip height gauge to measure the distance from the cylinder head casting to the tip of the stem. The measurements should be within specifications and consistent between valves. Stem tip height greater than specifications indicates a recessed valve seat or a necked valve stem. Correct valve stem height is important for proper rocker arm geometry and lifter operation. If the seats and valves are reconditioned, valve stem tip height must be restored. Valve stem tip height must be within specifications after assembly. If the step tip height is not correct, a valve may be held open. 5. The tip of the valve stem may become “mushroomed” as the rocker arm pounds against it (Figure 9-15). Use a file or cup-type grinding wheel to debur the stem before removing the valve. Do not drive a valve stem through the guide. This can result in guide damage. SERVICE TIP  Always refer to the service manual for the engine you are working on. Photo Sequence 20 is a typical example that may assist in the event a service manual is not available.

Caution The camshaft on an overhead camshaft cylinder head is under pressure. Not following service manual procedures for loosening the bearing caps may result in camshaft or cylinder head damage. Classroom Manual Chapter 9, page 182

Follow Photo Sequence 20 to disassemble a typical OHC cylinder head. The procedure for disassembling the OHV cylinder head is similar to that for an OHC cylinder head, except there are no camshafts. WARNING  Wear approved eye protection when disassembling the cylinder head. Parts may come loose suddenly and become airborne.

Valve stem seals are used to control the amount of oil traveling down the valve stem and to provide lubrication. These seals are constructed of synthetic rubber or plastic and are designed to control the flow of oil, not prevent it. There is no reason to reuse valve stem seals; they should always be replaced when reconditioning the cylinder head. However, inspection of the seals may confirm your diagnosis or indicate that additional inspection is required (Figure 9-16). Remove the O-ring and umbrella seals by simply lifting them off. Positive-lock seals can be removed by prying them off with a small screwdriver, pliers, or a special removal tool (Figure 9-17).

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Positive lock seal

391

Umbrella oil shedder

Figure 9-16  Inspect the old valve stem seals to confirm your diagnosis.

Figure 9-17  Special valve stem seal pullers.

PHOTO SEQUENCE 20

Typical Procedure for Disassembling an OHC Cylinder Head

P20-1  Tools required to perform this task include a cylinder head holding fixture, a valve spring compressor, a dial indicator, dial calipers, a softfaced hammer, an old piston pin, a pencil magnet, and a service manual.

P20-2  Mount the cylinder head holding fixture. Then reverse the tightening sequence to loosen the rocker arm shaft attaching bolts, and remove the rocker arm shafts from the cylinder head. Be sure to maintain the original order of the rocker arms.

P20-4  Measure camshaft end play by attaching the dial indicator so the contact point is against the front of the camshaft. Zero the dial while the camshaft is pried rearward.

P20-3  Remove the camshaft timing belt sprocket.

P20-5  Pry the camshaft forward, and note the indicator reading.

P20-6  Remove the camshaft from the cylinder head. If the head is equipped with cam followers, lash adjusters, or lash adjusting shims, remove them at this time.

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PHOTO SEQUENCE 20 (CONTINUED)

P20-7  Use a soft-faced hammer and an old piston pin to loosen the keepers from the retainers. Do not use heavy blows.

P20-8  Use a valve spring compressor to relieve valve spring tension. Compress the spring only enough to remove the keepers.

P20-9  Remove the keepers from the top of the valve stem. A pencil magnet can be used to lift off the keepers.

As the cylinder head is disassembled and inspected, keep good notes concerning worn or damaged parts. In your notes, indicate if machining or replacement parts are needed. After inspecting the components of the cylinder head and referring to your notes, you will be able to provide an accurate evaluation to the customer. You will be able to help the customer determine the most cost-effective way of correcting any faulty conditions. Depending on the shop, sources for parts include vehicle manufacturer’s dealerships, chain retail and jobber stores, independent parts suppliers, and recycled parts distributors. It may be less expensive to purchase a used part and recondition it than to attempt to recondition the part that was originally on the engine; for example, if a cylinder head with integral valve seats is found to have four worn seats requiring replacement, and two combustion chambers have cracks between the valve seats, it may be more beneficial to purchase a used cylinder head requiring only the seats to be cut. It may be necessary to remove manifold studs and rocker arm studs before the head can be machined. The studs can be either threaded in or press fit. Use a stud remover to remove threaded-in studs (Figure 9-18). Special stud pullers are available to remove press-fit studs (Figure 9-19). An alternative method for pulling press-fit studs is to place a deep socket or steel tube over the stud; then install a washer and nut onto the threads (Figure 9-20). As the nut is tightened against the washer, the stud is pulled from the cylinder head.

Figure 9-18  Use a stud remover to remove threaded studs from the head.

Figure 9-19  Stud puller used to remove press-fit studs.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service Stud Nut Washer Socket

Figure 9-20  Using a socket and nut to draw out press-fit studs.

CUSTOMER CARE  If metal erosion is evident and the apparent cause is not coolant leakage, advise the customer to avoid the use of chemicals not recommended by the vehicle manufacturer. Use of these types of chemicals may void the vehicle warranty.

Complete this segment of cylinder head disassembly by inspecting the cylinder head coolant and oil passages for dents, scratches, and corrosion. With the cylinder head completely disassembled, it is ready for cleaning. Some areas of the head and valves may require the use of a wire brush to remove stubborn carbon (Figure 9-21). Make sure all oil passages are open and clean.

Figure 9-21  Use a guide brush to clean carbon from the valve guides. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 9

VALVE INSPECTION

Classroom Manual Chapter 9, page 184

Modern automotive engines use poppet valves, which are opened by applying a force against their tips. The valve is closed by spring pressure. This opening and closing action results in wear of the valve face at the contact point with the seat (Figure 9-22). If this wear is excessive, the valve will not seal properly, resulting in poor engine performance and possible burned valves. Burned valves can also be caused by incorrect valve lash adjustment, weak valve springs, no valve rotation, lack of exhaust backpressure, uneven cooling at the valve, and lean air-fuel mixtures to name a few. Begin inspection of each valve using a close visual inspection. A normally worn valve will need to be cleaned of carbon. You will be able to see the seating contact area on the valve face (Figure 9-23). The valve in Figure 9-23 shows normal wear and will be refinished and put back into service. Look for indications of burning, galling, warpage, and bends. If the valve fails visual inspection, it must be replaced. Any valves passing the visual inspection must be measured for wear before reusing. Areas of the valve requiring measuring include the face, margin, head, and stem (Figure 9-24). Always compare the measurements against specifications.

Inspecting the Valve Head

Classroom Manual Chapter 9, page 184

Special Tools Outside micrometer Vernier calipers Machinist’s rule

All valves must be inspected for damage and wear. The valve must be completely clean to properly inspect it. The fillet area may become coated with hard carbon deposits (Figure 9-25). Before placing the valve into a cleaner, remove as much of the carbon as possible. Using an old valve to knock off the deposits works well (Figure 9-26). Since the fillet shape affects the flow of the air-fuel mixture around the valve, leaving any carbon in this area will disrupt the flow of the air-fuel mixture. A fine wire brush, buffing wheel, or parts tumbler can be used to remove stubborn carbon from the valve. Note the contact location of the valve face and seat. Proper seat contact is in the middle of the face (Figure 9-27). Incorrect contact areas can usually be corrected. Minor pits, grooves, and scoring can be removed during the refacing operation. Excessively worn valve faces require valve replacement. Excessive face wear

Normal face wear

Figure 9-22  Comparison between a normal valve face and a badly worn valve face.

Check stem tip for spread.

Check for thin (worn) lands between the keeper grooves (multiple bead valves).

Check for bent stem. Diameter

0.794 mm (1/32 in.) minimum

Valve face angle

Figure 9-23  This valve shows little carbon buildup and ­normal wear on the valve face; The carbon can be cleaned off of it.

Head diameter

This line is parallel to the valve face.

Figure 9-24  High-wear areas of the valve that must be checked.

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Figure 9-25  This valve has heavy carbon buildup that must be thoroughly cleaned.

Figure 9-26  Use an old valve to knock carbon off the fillet area. Actual seating surface Head Margin worn away Valve face

Figure 9-27  Proper seat contact should be centered on the valve face.

Face

Figure 9-28  If the margin is worn to less than 1/32 inch, the valve must be replaced.

Visually inspect the margin for excessive wear. The margin allows for machining of the valve face and for dissipation of heat away from the valve head. As the face wears, the margin may become thinner. If the margin is worn away, the valve may not dissipate the heat sufficiently, resulting in a burned valve, cupped head, or warped stem. If the margin is worn away to the point where the face and head form a sharp edge, the valve must be replaced (Figure 9-28). Use an outside micrometer or calipers to measure the diameter of the valve heads. Compare the results with the manufacturer’s specifications. When measuring the valve head, check in at least two directions to inspect for out-of-round. Use vernier calipers or a machinist’s rule to measure the width of the margin. The size of the valve margin must meet or exceed the manufacturer’s specifications for the valve face to be reconditioned. If specifications are not available, most manufacturers require at least 1/32 inch (0.8 mm) margin width. Also, the margin must be measured after refacing the valve to ensure the margin is still at least 1/32 inch (0.8 mm) wide.

Classroom Manual Chapter 9, page 184

Valve Stem Inspection The stem guides the valve through its linear movement. The stem also has valve keeper grooves machined into it close to the top (Figure 9-29). These grooves are used to retain the valve springs. The stem rides in a valve guide located in the cylinder head. The Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 9-29  Inspect the keeper groove(s) near the top of the valve stem.

Classroom Manual Chapter 9, page 184

continual movement of the valve may result in wear on the portion of the stem traveling in the guide. As the stem wears, the oil clearance increases. This results in excessive oil being pulled through the valve guide by vacuum into the combustion chamber and the formation of deposits on the valve. When visually inspecting the valve stem, look for galling and scoring. Either of these can be caused by worn valve guides, carbon buildup, or off-square seating. If the valve stem is scored, the valve is usually replaced. Also look for indications of stress. A stress crack near the fillet of the valve indicates excessive valve spring pressures or uneven seat pressure. Stress cracks near the top of the stem can be caused by excessive valve lash, worn valve guides, or weak valve springs. If a stress crack is found, replace the valve. SERVICE TIP  Burned valves are often caused by improper seat contact. This can be caused by worn valve stems or valve guides. Inspect all components before replacing the damaged valve.

Special Tools Outside micrometer

Special Tools Straightedge Feeler gauge set Bore gauge Inside micrometer Outside micrometer

Inspect the tip of the valve stem for wear and flattening. These conditions can be caused by improper rocker arm alignment, worn rocker arms, or excessive valve lash. Separation of the tip from the stem can be caused by these same conditions. Light wear can be corrected when the valve is reconditioned. If the stem is flattened excessively, causing the overall length of the valve to be below specifications, replace the valve. Another condition to look for during the visual inspection is necking. Necking is identified by a thinning of the valve stem just above the fillet (Figure 9-30). The head pulls away from the stem, causing the stem to stretch and thin. This condition is caused by overheating or excessive valve spring pressures. In addition, necking can be caused by exhaust gases circling around the valve stem. If the valve stem passes visual inspection, it must be measured for taper and wear. Measure the stem diameter in three locations using an outside micrometer (Figure 9-31). Measure the stem at the top, in the middle, and near the fillet. The diameter of the stem must meet specifications. As a general rule, taper should not be more than 0.001 inch (0.025 mm). Always refer to the manufacturer’s specifications when measuring valve stems. Many modern engines use tapered stems to provide additional clearance between the stem and guide close to the head of the valve. This additional clearance allows for expansion due to heat and reduces scuffing, galling, and sticking valves. A tapered stem usually has a diameter 0.001 inch (0.025 mm) smaller at the head than at the tip. If the valve stem diameter is smaller than specifications or excessively tapered, it must be replaced. Bent valve stems are not always identified during a visual inspection, yet a bent valve cannot be reused. The easiest method of detecting a bent stem is during the valve reface operation. With the stem secured in the chuck of the valve machine, observe the face as it approaches the grinding wheel. If the valve head wobbles, the valve stem is bent.

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Stem necking

Figure 9-30  A valve with a necked stem must be replaced.

Figure 9-31  Visually inspect the valve stem for scoring, and measure it for wear.

CYLINDER HEAD INSPECTION With the valves and valvetrain components removed from the cylinder head and the casting thoroughly cleaned, the head must be inspected to determine its serviceability. The cylinder head casting, valve guides, and valve seats are visually inspected and measured. Visually inspect the cylinder head for cracks and other damage. Remember, not all cracks may be visible to the eye. Therefore, it may be necessary to perform additional tests if a crack is suspected. Common locations for cracks are between the valve seats, from the spark plug hole and valve seats, or any location where the metal is thinned. If a crack is detected, the head must be replaced or the crack repaired. If the crack is to be repaired, perform this operation before performing any machining on the head. Some manufacturers do not recommend repairing cracks and suggest the cylinder head be replaced. Always follow the manufacturer’s recommendations. Inspect the mating surface to the block and the old gasket for indications of leakage. The leakage can be from the coolant passages into the combustion chamber, from the coolant passages to the outside of the head, or due to compression leakage between cylinders. Compression leaks are identifiable by trails of carbon adhering to the cylinder head. Also, aluminum heads with corrosion around the water passages must be resurfaced. Also look for gasket etching. If the etching is deep enough to catch your fingernail as you move across it, the head must be resurfaced. Next check the cylinder head’s mating surface to the block for warpage, using a straightedge and feeler gauge (Figure 9-32). Warpage can occur in any direction on the head surface. Measure for warpage along edges and three ways across the center (Figure 9-33). The head surface must be thoroughly clean to get accurate measurements. When checking for warpage on the ends of the head, be sure to rock the straightedge to the opposite side of the head. If this is not done, only half of the warpage will be measured. Compare the resulting measurements with specifications. In the absence of specifications, a general rule of thumb is 0.003 inch (0.08 mm) for any 6 inch (153 mm) length or 0.006 inch (0.18 mm) overall. Excessive warpage may indicate that the engine was overheated. If this is suspected, closely inspect the cooling system components. The feeler gauge can be used as a “go, no-go” gauge by using a feeler gauge that is the thickness of the maximum allowable warpage. If the feeler gauge fits under the straightedge, the warpage is over the maximum limit. If the feeler gauge fits under the straightedge, increase the thickness to determine the amount of warpage. Continue to increase the thickness until the feeler gauge has a noticeable drag as it is pulled from under the straightedge. This information is necessary to determine if the cylinder head can be resurfaced.

See Chapter 6 in the Classroom Manual for crack detection and repair methods.

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Feeler gauge

Precision straightedge

Figure 9-32  Use a straightedge and feeler gauges to determine warpage of the cylinder head.

Figure 9-33  Measure for warpage around the edges and across the middle of the cylinder head.

Use the straightedge and feeler gauge method to check for warpage of the intake and exhaust manifold mating surfaces. As a general rule, the maximum amount of warpage allowed in these areas is 0.004 inch (0.1 mm). In addition, check the valve cover rail for warpage. The spark plug side of an OHC cylinder head is usually warped more than the other side. If the cylinder head warpage is excessive, the cylinder head must be straightened using heat or resurfaced. This operation is usually completed in an automotive machine shop rather than an automotive repair shop. On OHC engines, the camshaft bores or saddles must be inspected for warpage. The most common causes of camshaft bearing wear in an OHC engine are misalignment of the bearing bores or saddles and lack of lubrication. As with most components, begin with a thorough visual inspection. Scoring or galling of the bearing surfaces may indicate one of the preceding problems. To check the camshaft bores or saddles of an OHC cylinder head for proper alignment, use a straightedge and feeler gauge (Figure 9-34). Alignment should not be out more than 0.003 inch (0.08 mm). It may be possible to correct camshaft bore alignment if the manufacturer allows it. This can be done by align boring and using oversized bearings or by using heat and special clamping fixtures to straighten the cylinder head. If the manufacturer does not recommend straightening or boring, the head must be replaced. Next measure the diameter of the bearing bores. If the cylinder head uses bearing caps, they must be installed and properly torqued before taking any measurements. Check for taper and out-of-round by measuring several locations in the bore. Oil clearance can be determined by measuring the journal of the camshaft, subtracting it from the measurement of the bore, and then dividing the difference by two. If the cylinder head uses camshaft bearing caps, oil clearance can be checked using plastigage (Figure 9-35). Excessive oil clearance may be corrected on some cylinder heads by align boring the camshaft bores and installing oversize bearings. Another method is to remove stock from the mating surfaces of the camshaft bearing caps. If the manufacturer does not provide for these corrective actions, the head must be replaced. Excessive clearance can be the result of lack of lubrication or oil contamination. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 9-34  Use a straightedge and feeler gauges to check ­camshaft bore alignment. Plastigage strip

Plastigage measure

Figure 9-35  On cylinder heads equipped with camshaft bearing caps, the oil ­clearance can be checked with plastigage.

SERVICE TIP  If the camshaft bearing bores are out of alignment, do not correct the problem at this time. Other operations such as resurfacing and straightening will affect bore alignment. Because of this, do bearing bore alignment after all other operations are completed. The valve guide clearance is the difference between the valve stem diameter and the guide bore.

Valve Guide Inspection Valve guides are designed with very tight tolerances to the valve stem. Worn valve guides are common causes for excessive oil consumption. Also, unusual valve seat wear patterns are an indication of valve guide wear. Before measuring the valve guide for wear, use a guide cleaner or bore brush to clean the guide. This ensures that any contamination is removed and accurate readings will be obtained. Refer to the appropriate service manual for the recommended procedure to measure valve guide clearance. One of the following methods is generally used: 1. Dial bore gauge. Zero the dial bore gauge using a special fixture. This is usually done by placing two identical new valves in the fixture and locating the dial bore gauge stem between them. This sets the correct size to zero the gauge. Insert the bore gauge into the valve guide, and rotate it. Also move the gauge through the length of the guide to determine taper. The measurement indicated on the gauge is the valve guide clearance.

Special Tools Bore brush Dial bore gauge Small hole gauge Outside micrometer Dial indicator Valve stem clearance tool Machinist’s rule

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Small hole gauge

Small hole gauge

Take measurement in three places.

Outside micrometer

Figure 9-36  A small hole gauge used to measure guide diameter. Measure the valve guide in three locations to determine the amount of taper and bellmouthing.

The valve guide clearance is the difference between the valve stem and the guide bore.

Figure 9-37  Use a micrometer to measure the size of the small hole gauge.

2. Small hole gauge. With the tool inserted into the guide, turn the thumb screw until the fingers of the tool contact the guide walls (Figure 9-36). After locking the tool, remove it from the guide. Then measure the expanded fingers with an outside micrometer to determine the guide bore size (Figure 9-37). Measure the guide in three locations to determine wear and taper. This provides a measurement for the valve guide bore. Subtract the diameter of the valve stem from this reading to determine the valve guide clearance. 3. Valve rock method. Install a new valve with a special sleeve tool into the valve guide (Figure 9-38). The special tool maintains the correct height of the valve during the check. Set up a dial indicator so the contact point is against the head of the valve at a right angle (Figure 9-39). The check is made in the direction of rocker arm movement. Note the reading on the dial indicator as the valve is rocked back and forth. The amount of wear is half that indicated by the dial. SERVICE TIP  If the special fixture is not available, use an outside micrometer set to the size of the valve stem and then zero the bore gauge to the micrometer.

Special Tools Machinist’s rule Seat width scale Valve seat runout gauge

4. Special valve stem clearance tool (Figure 9-40). Place the tool over the valve stem until it is fully seated, and then tighten the set screw. The tool maintains the specific height of the valve by allowing the valve to drop off of its seat until the tool rests on the upper surface of the guide. A dial indicator is set up to measure the movement of the tool as the valve is rocked back and forth. The clearance measurement is the reading obtained divided by two, the division factor of the tool. The desired stem-to-guide clearance is between 0.001 and 0.003 inch (0.025 and 0.080 mm) for intake valves and 0.0015 to 0.0035 inch (0.04 to 0.09 mm) for exhaust valves. As the valve travels back and forth through the guide, wear can occur. This wear is accelerated if there is a lack of lubrication, if the valve seat is worn, or if the valve stem is bent. Some manufacturers require a valve guide height measurement. This measurement is the measured distance between the spring seat and the top of the guide (Figure 9-41).

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Valve

Dial indicator Special tool

Valve

Figure 9-38  The special tool maintains the proper height to measure valve movement.

Figure 9-39  Rocking the valve will indicate guide clearance on the dial indicator.

Valve stem clearance tool

Valve guide height

Figure 9-40  Some manufacturers have special tools to measure guide clearance.

Figure 9-41  Some manufacturers require a valve guide height measurement.

Top Middle Bottom

Figure 9-42  Bellmouth wear is normal, but it must be corrected before servicing the seats and fitting the valves.

Integral valve guides with excessive wear can be reconditioned. If the cylinder head is equipped with guide inserts, they can be removed and replaced with new ones. Unequal forces created by valvetrain components can result in normal bellmouthing of the valve guide (Figure 9-42). This type of wear is due to the angle at which most valves Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 9

are installed into the combustion chamber. The angle causes the valve stem to create wear in one direction at the top of the guide and in the opposite direction at the bottom of the guide. When measuring the diameter of the valve guide bore, measure it in three locations to check for excessive bellmouthing and taper. Worn valve guides can cause excessive oil consumption, exhaust smoke, and burned valves. Excessive valve guide wear is often found on exhaust valves closest to the exhaust gas recirculation (EGR) valve. If a severely worn exhaust valve guide is found, it is recommended that the valve’s spring be closely inspected. Hot exhaust gases escaping past the guide will heat the spring, causing it to lose its strength. SERVICE TIP  If the special sleeve tool is not available, use a piece of rubber hose slipped over the valve stem. Cut the hose to the length at which it will hold the valve at its open position.

Valve Seat Inspection

If the valve guide is worn, the valve seat runout reading will not be accurate. Seat concentricity is a measure of how circular the valve seat is in relation to the valve guide.

Special Tools Spring compressor Air hose adapters

When the valve closes, it must form a seal to prevent loss of compression. This seal is provided by the contact of the valve face with the valve seat (Figure 9-43). In addition to sealing compression pressures, the seat and face provide a path to dissipate heat from the valve head to the cylinder head. There are two basic types of valve seats: integral and inserts. Most cast-iron cylinder heads have integral valve seats machined into the cylinder head. Valve seats must be inspected for cracks and excessive wear (Figure 9-44). Some heads with integral seats may be reconditioned even if the seats are damaged. This is done by boring out the original seat to accept an insert. Cylinder heads equipped with inserts must be inspected for loose seats. Pry on the seat to load it while checking for looseness. Use a machinist’s rule or a special seat width scale to measure the width of the valve seat (Figure 9-45 and Figure 9-72). If the valve seat width is not within specifications, the valve seat can be reconditioned. Due to the assortment of problems that can arise from improper seating, seat ­concentricity should be checked before and after cylinder head reconditioning. Use a valve seat runout gauge with the arbor installed into the valve guide bore (Figure 9-46). Slowly rotate the gauge around the valve seat while observing the gauge readings. Compare the test results with specifications, generally 0.002 inch (0.050 mm). Runout is the total indicator reading. If runout exceeds specifications, the valve seat will require refacing. Crack

Valve face cut to 441/2°

Valve seat cut to 45°, 1/16 in. wide Cylinder head

Figure 9-43  Proper valve face-to-seat contact is critical to proper engine performance.

Figure 9-44  Inspect the cylinder head closely for cracks. This head is cracked between the seats.

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Cylinder Head Disassembly, Inspection, and Service Seat width scale

403

Caution An accurate runout reading will not be obtained if the guides are worn. Always check valve seat runout after resurfacing the valve seat or the valve guides.

5

10

5

10

0

Figure 9-45  Measuring valve seat width.

Figure 9-46  Using a valve seat runout gauge to measure seat concentricity.

MACHINE SHOP SERVICES The following section describes cylinder head straightening, valve guide repair, and valve seat replacement. These services are generally performed at a machine shop or engine repair specialty shop. If you work in a general service repair shop or new car dealership, it is unlikely that you will perform this work. You will still perform the inspections of the cylinder head and instruct the machine shop on what needs repair. It is also important to review the work that was performed before reassembling the cylinder head. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 9

STRAIGHTENING ALUMINUM CYLINDER HEADS

Special Tools Brass shim stock Straightening fixture Thermal oven

Warped aluminum heads may be straightened, provided the manufacturer allows this operation. If the manufacturer does not recommend straightening, replace the head. If head straightening is an option, make sure to straighten an aluminum cylinder head after the valve guides are installed, but before any cracks are repaired or the valve seats are reconditioned. Otherwise the valve seat or guide inserts may fall out. Remove all screws, bearings, rocker arm studs, core plugs, oil gallery plugs, and any other hardware. The cylinder head is attached to a special fixture (Figure 9-47). A fixture can be made from a steel plate about 2 inches (50 mm) thick, surfaced on both sides to remove any warpage. Holes are drilled through the plate to attach the head. The attaching bolts align only with the center bolt holes of the cylinder head. This allows for expansion over the full length of the cylinder head. Coat the attaching bolt threads with an antiseize compound to prevent thread damage. Use the inspection report for the cylinder head to determine the size of shims required. Place brass shim stock one-half the total amount of warpage under each end of the cylinder head (Figure 9-48). The shims must extend the full width of the cylinder head gasket surface. Tighten the attaching bolts to a torque of no more than 25 pounds-feet (18 Nm). Place the cylinder head and fixture into a thermal oven heated between 4508F and 5008F (2328C and 2608C) for about 5 hours. Then shut off the oven and allow the heads to cool inside the oven. Recheck the warpage to determine if the process requires repeating. WARNING  The cylinder head will retain heat for a long time. Wear a good pair of insulated gloves when removing the cylinder head from the oven.

OHC Bearing Bore Alignment Special Tools Bore bar Dial bore gauge

The straightening process may correct any camshaft bore out-of-alignment; however, always recheck the bore alignment using a straightedge and feeler gauges. Also, recheck bore taper and out-of-round at this time. If it is determined the bore must be aligned, this can be done by line boring or align honing.

Head straightening fixture

Figure 9-47  The head is placed on a thick steel fixture and bolted down to straighten it. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Cylinder head

Brass shim stock Steel plate

Figure 9-48  Preparing the cylinder head for straightening. The shims must fit the entire width of the head.

If the cylinder head uses bearing caps to retain the camshaft, it is possible to restore the bearing bores to their original size without using oversize bearings. The inside diameter of the bearing bore is decreased by removing material from the cap at the parting line. WARNING  Always wear approved eye protection when grinding or cutting.

RESURFACING CYLINDER HEADS Heads should be refinished if warped. It is common to have heads pressure-checked and resurfaced during head gasket replacement. They are typically resurfaced using a belt sander, a surface grinder, or a milling machine. Belt sanding is quick and simple but is generally not the preferred method because it does not square the head and is not as precise as other methods (Figure 9-49). The surface grinder uses a stone with a cutting liquid that cools and helps to keep debris away from the surface being cut. It can produce a smooth finish but may take multiple passes, and grinding aluminum can load up the stone causing overheating and a poor finish (Figure 9-50). Milling can be precise and quick. It is possible to refinish a head surface in a single pass using a milling machine with a skilled operator and good equipment. A milling machine can use one or multiple cutters. Dry milling produces less mess and is preferred over wet milling (Figure 9-51). Head and block deck resurface quality is important because a refinished surface that is too rough, especially with MLS-type

Figure 9-49  Belt sanding.

Figure 9-50  Using a surface grinder.

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Chapter 9

Figure 9-51  Milling a head.

gaskets, may allow combustion gas or coolant to seep out. A refinished surface that is too smooth, especially with composite-type gaskets, may not hold the head gasket. If too much material must be removed from this surface, the compression ratio will increase as the deck height is lowered. These changes may result in detonation, intake manifold to head misalignment on V-type engines, retarded valve timing on OHC engines, pushrods too long on OHV engines, or even valve-to-piston contact. Most manufacturers require that the head be replaced. In some cases aftermarket head shims may be an option to restore the head height.

VALVE GUIDE REPAIR Classroom Manual Chapter 9, page 186

Knurling is a procedure in which a special bit is forced through a bore to swell the metal and decrease the bore size. The bore is then reamed to the specified diameter. Knurling is effective on valve guides with wear less than 0.005 inch (0.13 mm) over the specified clearance.

Valve guide repair is usually one of the first operations performed when reconditioning the cylinder head. The valve guides must be repaired or replaced before any valve seat work is performed. The guide is used as a pilot during seat replacement and seat refinishing; if the guide is worn, the seat may not be properly centered. There are several options available to the technician if it is determined the valve guides are excessively worn. These options include the following: ■■ Knurling the guide ■■ Reaming the valve to accept oversize valve stems ■■ Replacing insert guides ■■ Installing guide liners ■■ Replacing integral guides with false guides ■■ Installing coil inserts Regardless of the method used, it is vital that the valve guide is centered so the valve face will be concentric in its seat. Also, after the guide is repaired, always clean it before assembling the valves. Most operations will leave metal chips and debris that will result in premature failure if not removed.

Knurling Classroom Manual Chapter 9, page 186

Knurling can be done using a thread-type arbor (Figure 9-52). Knurling arbors are generally available in 5/16 -inch, 11/32-inch, and 3/8-inch (7.937-mm, 8.731-mm, and 9.52-mm) sizes. In addition, knurling arbors are available in 0.005 inch (0.13 mm) over standard to accommodate oversize valve stems. Following is a typical procedure using the thread-type knurler:

1. Clean the valve guides. 2. Select a knurling arbor that is the normal size of the valve guide. 3. Lubricate the guide and arbor. 4. Install the arbor into the guide from the combustion chamber side. 5. Use a tap handle to hand start the arbor into the guide. Be careful not to rock the arbor while starting it.

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Figure 9-52  This cylinder head bench has an assortment of knurling bits.

6. Using an electric drill equipped with a speed reducer (1,200 rpm to 1,600 rpm), drive the arbor into the guide (Figure 9-53). The arbor will feed itself down the guide. Do not back the arbor through the guide. Once the arbor is through the guide, release it from the drill chuck. If the motor stalls, remove the motor and ­finish the guide by hand. 7. Clean the guide with solvents and a bore brush. 8. Select the correct-size reamer to obtain one-half the specified clearance. The reamer size selected is usually 0.001 to 0.002 inch (0.025 to 0.050 mm) larger than the valve stem diameter.

Special Tools Knurling bit Electric driver Speed reducer Reamer Guide hone Deburring tool

Drill chuck

Speed reducer

Good

Knurling arbor

Valve guide Bad

Figure 9-53  Driving the knurling arbor into the valve guide. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Special Tools Reamer

Caution When selecting valve guide inserts or liners, match guide materials to valve stem materials. Silicon-bronze guides are not compatible with stainless steel stems. If this type of guide is used, the stems must have a hard chrome finish.

WARNING  Always wear approved eye protection whenever performing this task.

Oversize Valve Stems If the valves are going to be replaced anyway, it may be more cost-efficient to install valves with oversize stems. The only operation involved is to ream the valve guide to the next oversize and then replace the valve to obtain the correct clearance. Valves are available in these standard stem oversizes: 0.003, 0.005, 0.006, 0.010, 0.013, and 0.015 inch.

Guide Replacement Guides that are worn too excessively to be knurled can be replaced using special inserts. If the original valve guide is insert designed, the old insert can be driven out and a new one can be installed. On integral guides, the technician may choose to use coil inserts, liners, or false guides.

Liners are thin tubes placed between two parts.

Special Tools Guide driver Scale Small hole gauge Micrometer Reamer Guide hone

9. Insert the pilot end of the reamer into the guide, and use a tap handle to turn the reamer clockwise (Figure 9-54). If a cast-iron guide is used, do not lubricate the guide. If the guide is bronze, it must be lubricated with high-pressure lubricant. 10. If a closer clearance is desired, use a guide hone until the desired clearance is obtained. 11. Use a deburring tool to remove irregularities in the guide.

Insert Guides.  The old insert guide must be pressed out using a special guide replacement tool (Figure 9-55). The tool fits into the guide and has a shoulder slightly smaller than the outside diameter of the guide. The tool can be used with a press or a heavy hammer. Using a press is best since it applies a constant force. Special drivers that attach to an air hammer can be used. The insert usually has a 0.001- to 0.002-inch (0.025- to 0.050-mm) interference fit into the cylinder head. The direction in which the guide is removed varies between manufacturers. For this reason, always refer to the appropriate service manual for the recommended procedure. Some manufacturers use guides with an angle cut on one end. Never attempt to remove or install these guides by pressing against the angle cut. WARNING  Always wear approved eye protection when driving or pressing guides out or installing them.

Valve guide reamer Valve guide punch

Figure 9-54  After the guide is knurled, a reamer is run through to obtain the desired clearance.

Valve guide

Figure 9-55  Removing the old guide with a guide driver.

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Figure 9-56  False guides can be installed to correct excessive valve guide wear.

Integral Guides.  A variety of machining operations makes it possible to recondition cylinder heads with worn integral valve guides. Depending on the amount of wear, the guide can be repaired using a liner, false guide, or coil inserts. If valve guide wear is within 0.030 inch (0.80 mm) of standard, a thin-wall liner can be used to restore original clearances.

SERVICE TIP  If the insert guide is hard to drive out, heat the head in an oven at 250°F (121°C).

If the wear is greater than 0.020 inch (0.50 mm), the guide can be drilled out to accept a false guide (Figure 9-56). Another accepted method of guide repair involves the installation of a bronze coil insert. This method involves threading the inside of the original guide bore to accept a coil. The coil insert reduces the inside diameter of the guide. The coil is finished to obtain the desired clearance. Like knurling, the clearance can be halved since the threads trap sufficient oil.

A false guide is a replacement guide that is installed in the cylinder head in place of the original valve guide.

REPLACING VALVE SEATS If the cylinder head uses insert valve seats, excessively worn seats should be replaced and ground to ensure proper sealing. Lightly worn insert seats and integral seats can usually be cleaned up by resurfacing the seat. If the seat is damaged too extensively to be restored by surfacing, the seat will have to be replaced. Always resurface new valve seats to ensure proper concentricity.

Classroom Manual Chapter 9, page 186

Insert Valve Seat Replacement The procedure for replacing insert valve seats is as follows: 1. Remove the original insert by prying it out of the head or using a special seat remover (Figure 9-57). Remove all inserts that are to be replaced. 2. Thoroughly clean the insert counterbore. Check this area closely for cracks. If any cracks are found, they will have to be repaired before proceeding. 3. If the counterbore does not require recutting to accept oversize inserts, go to step 8. Recut the counterbore using a pilot installed in the guide, and mount the base and ball shaft assembly to the sealing surface of the cylinder head (Figure 9-58). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 9 Feed handwheel Drive motor input Swivel casting Puller

Chisel

Mounting base

Grinding wheel Counterbore

Figure 9-57  Removing the old valve seat inserts.

Special Tools Seat remover Counterbore cutter Pilot and ball shaft Driver motor Thermal oven Insert driver

Figure 9-58  Cutting the counterbore to accept a new seat insert.

4. Set an outside micrometer to the recommended counterbore size. Use the micrometer to set the cutter head to this size. The recommended size is usually set to provide a 0.005- to 0.008-inch (0.13- to 0.20-mm) interference fit. 5. Place the counterbore cutter over the pilot and ball shaft. 6. Set the depth of the insert at the feed screw. 7. Turn the stop collar to cut the counterbore. Apply cutting oil to the cutter at regular intervals. Continue until the stop collar reaches the preset depth. 8. Place the cylinder head in a thermal oven set at 350°F to 400°F (177°C to 204°C). While the cylinder heads are heating, place the inserts in a freezer. 9. Use an insert driver to press the new insert into the counterbore. Make sure the insert is flush and fully seated. 10. After all inserts are installed, stake or peen the edge around the outer edge of the insert (Figure 9-59). SERVICE TIP  If the original valve seat failure is the result of recession, replace the seat with hardened seat inserts. Recession is common on early 1970s engines, when lead was removed from fuels.

Integral Valve Seat Replacement If the cylinder head is equipped with integral valve seats, a counterbore is cut into the original seat to accept a new seat insert. The counterbore must provide a 0.005- to 0.008-inch (0.13- to 0.20-mm) interference fit with the seat insert. For the counterbore to be centered, the valve guides must be reconditioned before doing this operation. The procedure for counterboring and installing insert seats into a cylinder head with integral seats is similar to the insert replacement discussed previously. Removal and installation of integral-type valve seats is as follows: 1. Thoroughly clean the area around the seats. 2. Install a pilot into the guide, and mount the base and ball shaft assembly to the sealing surface of the cylinder head. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Arbor Nut

Insert seat Peening tool point

Figure 9-59  Peening the valve seat insert ensures that it will not come loose during operation.

3. Set an outside micrometer to the recommended counterbore size. Use the micrometer to set the cutter head to this size. 4. Place the counterbore cutter over the pilot and ball shaft. 5. Set the depth of the insert at the feed screw. 6. Turn the stop collar to cut the counterbore. Apply cutting oil to the cutter at regular intervals. Continue until the stop collar reaches the preset depth. 7. Place the cylinder head in a thermal oven set at 350°F to 400°F (177°C to 204°C), while freezing the inserts. 8. Use an insert driver to press the new insert into the counterbore. Make sure the insert is flush and fully seated. 9. After all inserts are installed, stake or peen the outer edge of the insert.

Caution Do not continue to hit the driver after the insert is fully seated, or the insert may break.

SERVICE TIP  To remove difficult inserts, weld a small bead around the inside of the seat. This will shrink the seat, allowing easier removal.

WARNING  Always wear approved eye protection when performing this task.

REFINISHING VALVES AND VALVE SEATS Most valve machining work is sent out to a local machine shop. There the technicians perform this work daily and can efficiently produce refinished cylinder heads. Many general repair shops cannot afford to purchase the high-tech equipment required to refinish late-model cylinder heads. The general repair shop will often make more money on the job by subletting the machine work out to a local and trusted machine shop. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Caution Always wear approved eye protection when performing this task.

In some cases, the job of refinishing the valves and valve seats may still be performed in the general repair shop. Many older facilities still have the equipment and will use it to perform the valve work if the cylinder head is in good condition otherwise. First the valves are all refinished; then the seats are refinished and the valves fitted to the seat to ensure that the contact area is correct on the valve face.

Valve Reconditioning Caution Sodium-filled exhaust valves should not be machined, they can explode if overheated.

An interference angle may or may not be specified by the manufacturer. It means that the valve face and valve seat are cut at angles that are ½ to 1 degree different from each other to improve sealing.

A valve grinding machine is required to reface the valves (Figure 9-60). You want to cut as little metal off the valve face as possible while still removing all cupping and pitting. Make sure the valve face and stem are clean. This ensures that the cutting stone will not get loaded with carbon and that the valve will sit squarely in the mounting chuck. Make sure you have enough margin left to cut the valve face. There are several different types of valve grinders available; you will have to become familiar with the one used in your shop. The following guidelines apply to most valve grinding equipment: 1. Refer to the manufacturer’s specification to determine at what angle the valve face should be cut. Sometimes an interference angle is used. This is a difference in angle between the valve face and the valve seat of ½ to 1 degree. It promotes better sealing by increasing the valve seating pressure due to less contact area. In most cases the interference angle will wear down within a couple hundred miles. 2. Adjust the valve holding bench to the specified angle. 3. Use the diamond tip stone dresser to put a good clean finish on the stone. Use lubrication while cutting. Take as little material off as necessary. Make several fast passes across the diamond while you are removing material; then finish the stone by moving it slowly across the diamond several times to smooth the surface finish (Figure 9-61). 4. Place the valve in the holding chuck as close to the neck as possible. Be sure the balls of the chuck are contacting the machined part of the stem. Spin the valve, and check for runout of the valve head. You can set up a dial indicator to measure runout as you spin it in the chuck. Replace a valve that has over 0.002-inch (0.050-mm) runout as shown by the total indicator reading (TIR). 5. If possible, set the mechanical stops on the bench (Figure 9-62). Move the valve in close to the stone. You want the valve to move all the way across the stone so as not to develop a groove in your freshly dressed stone. Adjust the stops so the valve does not travel beyond the end of the stone; this can nick the valve as it runs back up onto the stone. You also want to set the stops so you prevent the stone from contacting the neck of the valve. If you nick the neck of the valve, the valve must be replaced.

Figure 9-60  A typical shop valve grinding machine. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 9-61  Pass the stone across the diamond cutting tip to clean the face of the stone.

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Figure 9-62  Adjust the stops on the bench so you cannot nick the valve neck and so you use the whole stone.

6. Turn the chuck and the stone on, and adjust the lubrication so it hits the valve face. 7. Slowly move the valve into contact with the stone, while simultaneously moving the stone back and forth across the valve (Figure 9-63). If equipped, set the depth indicator to zero. Move the stone quickly, and adjust the valve into the stone slowly, until you can see no more pitting. Then put a nice finish on the face by making slow passes across the valve. Move the valve away from the stone, and turn off the machine. Look at the depth indicator to see how much material you removed from the valve. 8. Carefully inspect the valve, and continue grinding if pits or cupping are still seen. 9. Measure the margin, and be sure you have enough left to reuse the valve. If not, ­discard the valve; if the valve is OK, proceed to the next step. 10. Next, you need to dress the valve tip to make a clean smooth surface to contact the rocker arm. You also want to remove the same amount of material from the tip as you did from the face so you don’t disturb the rocker arm geometry. If you have depth indicators, simply match the amount of material you take off the tip with what you removed from the face. On machines without this measuring equipment, you will have to gauge this by feel and then measure valve installed height. 11. Dress the tip cutting stone, usually on the end of the valve grinder (Figure 9-64).

Figure 9-63  Draw the valve into the stone while both are rotating. Set the oil so it is running over the valve face.

Figure 9-64  Run the valve tip back and forth across the stone to dress the tip.

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Figure 9-65  Rotate the valve in the holder, and put a light chamfer on the edge of the valve tip.

Special Tools Counterbore cutter Pilot and ball shaft Driver motor Thermal oven Insert driver

Special Tools Valve machine

12. Place the valve in the holder, and adjust the lubrication to hit the tip. Move the stone into the valve tip slowly while rocking the valve back and forth across the stone. Proceed until the tip is fully freshened. 13. Finally, place the valve in the chamfering holder. Very gently push the valve against the stone to produce a slight chamfer. All you are trying to do is to eliminate the sharp edge of the tip; a deep chamfer is not desired (Figure 9-65). 14. Repeat the process for each of the valves. Many technicians will refinish the face of each valve and then refinish the tips to avoid resetting the stops on the stone bench.

SERVICE TIP  For cylinder heads with the valve guides set at an angle in relation to the cylinder head surface, it will be necessary to set the base in the direction of the centerline of the valves.

The end result should be a perfectly cleaned-up valve face and tip with a margin at least as thick as specified.

Valve Seat Refinishing Special Tools Pilots Stone assortment Stone holder Power head Diamond dressing tool Lapping stick Prussian blue Machinist’s rule Valve seat concentricity gauge Dressing bit

The valve seats must be fully refinished to provide a good sealing surface for the fresh valves. You will have to achieve a good finish on the seat and the proper seat width. Remember, typical specifications are 1/16 inch on the intakes and 3/32 inch on the exhausts, but check your particular specifications. It is best to clean the valve seats and port area with a light wire brush if the head has not been professionally cleaned. This saves the stones and cutters from getting loaded up with carbon. There are several types of valve seat refinishing equipment. A diamond cutter type is shown in Figure 9-66. This bench includes valve guide pilots, knurling tools, diamond seat cutters, and an overhead drill for cutting the seat (Figure 9-67). Another type of seat cutter is an adjustable carbide cutter that can cut three angles on the seat in one shot. Other seat cutting equipment uses stones of different sizes and angles. This has been the traditional method for years, but equipment is often being replaced by the other styles. Any type of equipment is designed to achieve the same effects on the valve seats.

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Cylinder Head Disassembly, Inspection, and Service

Figure 9-66  These diamond seat cutters are long lasting and do an excellent job of refinishing the seats.

415

Figure 9-67  The machine shop uses this bench for much of the seat work.

SERVICE TIP  Be careful not to remove too much material from the grinding stone in one pass. Grinding stones and diamond tip dressers are expensive, but can last a long time with good maintenance and if used as directed.

Carbide Seat Cutters To use the carbide cutter, adjust the cutters to fit the seat (Figure 9-68). The cutter shown has a guide pilot in it. With any cutting procedure, you must select a proper fitting pilot that fits securely in the guide to ensure that you cut the seat squarely in relation to the

Figure 9-68  This adjustable carbide seat cutter cuts all three angles at one time while maintaining the correct seat width. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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guide. Some cutters are designed to be used with a drill; others can be turned by hand. Rotate the tool clockwise. Follow the equipment instructions. Remember, these cutters cut the seat and finish it to the correct width. It performs a three-angle valve job. The seat is typically cut at 45 degrees, and there is a 15-degree or 30-degree angle on the top of the seat and a 60-degree or 75-degree angle cut on the lower part of the seat, in the throat.

Stone Seat Cutters The stone-type refinishing equipment, whether diamond or traditional, uses very similar processes. We’ll discuss the stone seat cutting procedure here. When using a stone, it must be dressed like the stones on the valve grinding machine. Diamond cutters do not require refinishing; they should theoretically last forever unless the diamonds break free from the tool. To refinish a seat using a stone cutter: 1. Select a 45-degree stone (or 30-degree stone if that is the seat angle) that fits the seat without scraping on any portion of the combustion chamber. It must be large enough to cut the whole width of the seat (Figure 9-69). 2. Fit the stone onto the drilling tool (Figure 9-70). 3. Place a drop of oil on the stone dressing shaft, and place the stone and tool onto the shaft. Select the proper angle at which the diamond cutter will cut the stone. 4. Apply the power head (special drill) on top of the stone holding fixture, and spin the stone. Support the weight of the power head, and hold it squarely on the stone. Slowly move the diamond cutter into the stone while moving it quickly up and down across the stone (Figure 9-71). Finish the stone by taking several slow passes across the stone. 5. Make sure the guide is clean, and select the proper pilot (Figure 9-72). The pilots are tapered. They should fit snugly and not quite bottom out on the guide. They are sized as 9/32 (as an example), 9/32 11 (0.001 in.), 12, 13, —1, and so on for each different size guide. 6. Place a drop of oil on the pilot, and place the stone and its holder over the pilot. 7. Spin the stone on the seat while supporting the weight of the power head and holding it squarely above the stone. Spin the stone for just a few seconds at a time; check the seat between cuts. You want to take little material off but remove all pitting from the seat (Figure 9-73).

Figure 9-69  Stones are still a fine way to refinish seats; you just need some patience. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Figure 9-70  Fit the stone on its holder to get it ready for use with the power head.

Figure 9-71  Pass the diamond across the stone to freshen up the stone.

Figure 9-72  Use this tool to secure the pilot into the guide. It is also very helpful when removing the pilot.

Figure 9-73  Make short cuts on the seat with the stone. Check the seat often; you want to take as little material off as possible.

Fitting the Valve and Seat Once the valve and seat are clean, you must narrow the seat (usually) and check to see where the valve face is contacting the seat. Check the manufacturer’s specifications, and compare the seat width to the specification (Figure 9-74). You want the area of contact Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 9-74  Measure the width of the seat using a machinist’s rule. Intake seats are ­typically 1/16 inch, and exhausts are often 3/32 inch.

Prussian blue is a thick ink used to show the area of seat contact on the valve face. Topping a seat with a 15-degree or 30-degree stone narrows the valve seat and lowers the area of contact toward the tip. Throating a seat with a 60-degree or 75-degree stone narrows the valve seat and raises the area of contact toward the head.

Figure 9-75  Rotate the valve in the head with a lapping stick to see where the seat is contacting the valve.

to be near the center of the face, with some area above and below the contact patch still left on the face. To check where the seat is contacting, dab a little Prussian blue on the valve face and use a lapping stick to spin the valve on the seat (Figure 9-75). The Prussian blue will be rubbed away from the contact patch. If the contact is high (Figure 9-76) toward the head, you will cut a 15-degree or 30-degree angle on the top of the seat to narrow the seat and adjust the valve contact down (Figure 9-77). This is called topping, and it is the most common requirement when using refinished valves because they tend to sink down in the head as they wear. If the seat is wide and the area of contact is low on the valve face, toward the tip, cut the seat with a 60-degree or 75-degree stone in the throat. Throating will narrow the seat and move the area of contact up toward the head. Continue adjusting until you have the correct seat width and contact area on the valve face. Always finish the seat with a short burst with the 45-degree stone. This removes any burrs that could be left on the seating surface by the other cuts. Make a final check of the contact area using Prussian blue. Next you should check the concentricity or runout of the seat. If it is concentric, it means that it is centered to the valve guide. Use a dial indicator seated in the guide to check that the seat runout is less than 0.001 inch. Cut with 30-degree stone to narrow seat and lower contact

45°

30°

Contact patch too high toward head

Seat width too wide

60°

Figure 9-76  The 3-degree angle valve seat cuts.

Figure 9-77  Cut a 30-degree angle on the top of the seat to narrow the 45-degree seat, and move the contact down toward the tip.

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Some technicians will perform a three-angle valve job on every job. This means they will cut the 45-degree seating angle, a 15-degree or 30-degree topping cut, and a 60-degree or 75-degree cut in the throat. In production work on a stock engine, this is not required. Finally, you need to check the integrity of the valve face to the seat. You can apply a vacuum to the valve seal stand or the top of the guide, and make sure each valve can hold a vacuum. Alternately, you can pour a clean solution of parts cleaner or mineral spirits on top of the valves, and make sure none leaks down within 1 minute. Photo Sequence 21 shows step-by-step directions for refinishing valve seats.

Valve Measurement Valve stem height should be measured to determine if more material needs to be ground off the valve stem tip. After the seat and face refinishing, the valve stem will sit higher above the head. This measurement is particularly important on engines with nonadjustable hydraulic lifters. If you install the lifter and the tip is extending too far, the lifter may not allow the valve to close. Measure stem height (if specified), using a machinist’s rule, from the base of the head to the top of the tip (Figure 9-78). Compare the measurement to specifications. If the stem is too tall, grind the required amount off of the tip.

Valve stem height is the height of the valve tip as measured from the base of the head to the top of the valve tip.

Valveinstalled height

Figure 9-78  Measure the height of the valve stem from the cylinder head to the valve tip.

CASE STUDY The technician had diagnosed an oil consumption concern as worn valve guides. With the cylinder head removed from the engine block, the technician cleaned, disassembled, and carefully inspected it. The guides were excessively worn, but upon closer examination it was found that some of the seats were not concentric. After consulting with and explaining the condition to the vehicle owner, the technician performed the repair. Simply replacing or reconditioning the valve guides would have resulted in a comeback, as the valves would not have sealed properly. Careful inspection saves time and money, as well as earns you respect from your customers.

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PHOTO SEQUENCE 21

Typical Procedure for Grinding Valve Seats

P21-1  Select the correct size and grit of stones required. Select the stones required for the seat, for topping, and for throating.

P21-2  Thread each stone onto a stone holder. Using a holder for each stone will reduce the amount of time required to recondition the seats and will keep stone location consistent.

P21-3  Dress each stone by attaching the stone holder to the grinder motor and using a diamond dressing tool. The stones should be dressed before use on each seat. If the surface finish is rough or shows indications of chatter, redress the stone.

P21-4  Select the proper size pilot and pass it through a cloth saturated with oil. Do not squirt oil into the valve guide.

P21-5  Insert locating pilots into each of the valve guides by pushing the pilot down while twisting it until it firmly wedges in place. The pilot should extend at least 2½ inches from the seat to fit inside the stone holder.

P21-6  Locate the lifting spring over the pilot. Lubricate the pilot with a few drops of motor oil.

P21-7  Place the stone holder, with the proper stone for the seat, over the pilot. Check its fit onto the seat.

P21-8  Attach the driver motor to the holder. Hold the driver with the pistol grip in one hand, supporting the weight. Cradle the front of the driver with the other hand.

P21-9  Turn on the motor and work the stone into the seat. When working the ­grinding stone, lift it on and off the seat at a rate of 120 times per minute to prevent excessive pressures on the stone and seat.

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PHOTO SEQUENCE 21 (CONTINUED)

P21-10  Remove only enough material to provide a new surface all around the seat. Grind for only a few seconds, and stop to check the work.

P21-11  Check the width of the seat with a scale.

P21-12  Top and throat the valve seat to obtain the proper seat width.

P21-13  Check valve seat concentricity by placing the fixture over the guide pilot.

P21-14  Check the fit of the valve into the seat by coating the valve face with a light layer of Prussian blue and then placing the valve into the seat.

P21-15  Rotate the valve back and forth onequarter turn while applying pressure to the center of the valve.

P21-16  Remove the valve, and inspect the contact pattern on the valve face and seat.

P21-17  If the valve seat-to-face contact requires correction, this is done by topping and throating the seat. If the seat contact is high, topping the seat will lower the contact area. When the seat is finished, the surface must be free of any chatter marks.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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ASE-STYLE REVIEW QUESTIONS 1. Reconditioning valves is being discussed. Technician A says that the valve is stroked across the stone at the same time it is fed in. Technician B says to back the valve out of the stone when the last pass is complete. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that the valve head runout can be checked with the valve in the valve machine. Technician B says that a total indicated reading (TIR) greater than 0.002 inch (0.05 mm) on the valve head requires valve replacement. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 3. Guide replacement is being discussed. Technician A says to match guide materials to valve stem materials when selecting valve guide inserts or liners. Technician B says that all guides are removed toward the combustion chamber. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. Installing guide inserts is being discussed. Technician A says to measure the amount the guide protrudes from the head casting so the new guides can be installed to the same height. Technician B says to cut a chamfer on the insert if the insert does not have one. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Reconditioning OHC cylinder heads is being discussed. Technician A says that the cylinder head warpage does not affect the camshaft bearing bore alignment. Technician B says if the head is to be straightened by heat, brass shim stock equal to the thickness of the total amount of warpage is placed under each end of the cylinder heads.

Who is correct? A. A only B. B only

C. Both A and B D. Neither A nor B

6. Reconditioning valve seats is being discussed. Technician A says that if the seat is too narrow, it is corrected by using the same degree stone as the valve seat angle. Technician B says to throat the seat if the valve seat is too wide. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 7. Technician A says that valve guides can be ­pearlized to restore them to their original condition. Technician B says that worn valve guide inserts can be pressed or driven out and new ones installed. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 8. Technician A says to try to take as much material off the valve stem tip as you did off the face. Technician B says that you should put a light chamfer on the tip. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 9. Technician A says that the valve guide must be clean and not worn excessively before repairing valve seats. Technician B says to pick a guide pilot that slides down to the bottom of the guide easily. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. A valve seat is too wide. The area of contact is high toward the head of the valve. The seat should be cut with a _______________ stone. A. 30-degree C. 45-degree B. 44-degree D. 60-degree

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ASE CHALLENGE QUESTIONS 1. What preparation must be done to the valve guides before measuring valve seat runout? A. Use 30W engine oil to lubricate the guide. B. Clean the valve guide with a bore brush. C. Ream the valve guide to its original diameter. D. Use a pilot to hold the guide in place. 2. Technician A says that a worn-out valve guide will provide an inaccurate valve seat runout measurement. Technician B says that the valve seat-to-face ­contact area provides a path for heat from the valve head to dissipate. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. All of the following are considerations when grinding valve seats except: A. Dress the stone before grinding any seat. B. Remove only enough material to provide a new surface. C. Use transmission fluid to lubricate only the stone. D. Do not apply pressure to the grinding stone. 5. Technician A says that if the valve seat is too ­narrow, the valve may burn. Technician B says that if the valve seat is too wide, the valve may not seal properly. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. An acceptable intake valve seat width is: A. 1/ 16 inch (1.58 mm). B. 3/16 inch (4.76 mm). C. 7/ 32 inch (5.56 mm). D. ¼ inch (6.35 mm).

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

425

JOB SHEET

54

REMOVING THE HARMONIC BALANCER AND PULLEY Upon completion of this job sheet, you should be able to properly remove and reinstall the harmonic balancer or crankshaft pulley. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: C.1.

Remove, inspect, or replace crankshaft vibration damper (harmonic balancer).

Tools and Materials • Technician’s tool set • Harmonic balancer or gear puller (or specialized manufacturer tool as needed) Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific engine. Write down the information, and then perform the following tasks: 1. Locate the service steps for removing the harmonic balancer in the service manual. Briefly outline the steps and special tools needed to remove it, as outlined in the service manual. _________________________________________________________________________ _________________________________________________________________________ 2. If needed, remove the drive belt and any sensors that would interfere with the removal of the harmonic balancer.

h

3. Set up the puller tool to remove the balancer. The fingers/claws should grab the pulley in the same area as each other and should be behind the pulley instead of in the grooves (if space permits). Some pullers are bolted directly to the harmonic balancer.

h

4. Determine which parts of the main threaded rod are going to be used when pulling the balancer off. Use chassis grease (or any other thick grease) on those threads.

h

5. Using a socket and ratchet, turn the threads and remove the harmonic balancer. Make sure to use caution not to damage or chip the crankshaft, and (if applicable) save the woodruff key that may fall out.

h

6. After removing and inspecting the harmonic balancer, clean the crankshaft and threads with a clean cloth.

h

7. Explain how you are going to hold the crankshaft from turning. _________________________________________________________________________ _________________________________________________________________________ 8. Reinstall the bolt. Torque it to the manufacturer’s specification.

h

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Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

427

JOB SHEET

55

CYLINDER HEAD REMOVAL Upon completion of this job sheet, you should be able to properly remove a cylinder head from an engine. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.1. Remove cylinder head; inspect gasket condition; install cylinder head and gasket; tighten according to manufacturer’s specifications and procedures. Tools and Materials • Technician’s tool set • Penetrating oil Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Use an engine in a vehicle or on a stand to perform the following steps to remove the ­cylinder head. 1. Locate the service information procedure for removing the cylinder head from your engine. Read through the procedure, and list in order the components that must be removed from the head before removal from the engine. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Install safety glasses and fender covers. Disconnect the negative battery cable.

h

3. Remove all wiring connectors, vacuum lines, and hoses as needed. Mark them carefully for reinstallation.

h

4. Follow the manufacturer’s procedure to remove the valve cover(s). What type of valve cover is used on your engine? _________________________________________________________________________ 5. Follow the manufacturer’s procedure to remove the intake manifold. Be sure to follow the loosening sequence or reverse the tightening sequence. Describe the pattern in which you loosened the attaching fasteners. _________________________________________________________________________ _________________________________________________________________________

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Task Completed 6. Spray the exhaust manifold nuts with penetrating oil, and allow them to soak for a minute. Remove the exhaust manifold while following any special instructions offered in the service information.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

429

JOB SHEET

56

CYLINDER HEAD DISASSEMBLY Upon completion of this job sheet, you should be able to disassemble a cylinder head properly. This job sheet addresses the following AST/MAST task for Engine Repair: B.1. Remove cylinder head; inspect gasket condition; install cylinder head and gasket; tighten according to manufacturer’s specifications and procedures. Tools and Materials • Technician’s tool set • Parts washer • Valve spring compressor Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Using the cylinder head(s) that you removed from the engine and the proper service ­manual, you will identify and perform the required steps to disassemble the cylinder head. 1. On what page of the service manual are the cylinder head disassembly procedures found? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What components of the cylinder head must be removed prior to removing the valves? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. List any special tools and equipment required to disassemble the cylinder head. After making the list, gather the tools and organize them in your area. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Clean the cylinder head and mount the head to the holding fixture.

h

5. If working on an OHV cylinder head, go to step 12. On OHC cylinder heads, reverse the tightening sequence to loosen the rocker arm shaft attaching bolts, and remove the bolts.

h

6. Remove the rocker arm shafts from the cylinder head. Be careful to maintain the original order of the rocker arms.

h

7. Remove the camshaft timing belt sprocket.

h

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Task Completed 8. Measure the camshaft end play, and record your reading. _________________________________________________________________________ 9. Remove the camshaft from the cylinder head.

h

10. If the head is equipped with cam followers, lash adjusters, or lash adjusting shims, remove them at this time. Be careful to maintain proper order of all components.

h

11. Use a soft-faced hammer and an old piston pin to loosen the keepers from the retainers. Do not use heavy blows. Be sure the head is mounted on head stands to avoid bending valves.

h

12. Use a valve spring compressor to compress the valve springs. Compress the springs only enough to remove the keepers.

h

13. Remove the keepers from the top of the valve stem.

h

14. Slowly release the valve spring compressor until it can be removed. Remove the valve spring retainer, valve spring, valve spring shims, and stem seal. Maintain proper order of the valve spring components to the cylinder head.

h

15. Measure the thickness of any spring shims used, and record the results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 16. What type of stem seal is used on this cylinder head? _________________________________________________________________________ 17. Measure the valve stem tip height, and record the results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 18. Use a file to remove any mushrooming at the top of the valve stem.

h

19. Remove the valve from the cylinder head.

h

20. Repeat this procedure for all valves. Organize the components so their original positions in the cylinder head are maintained.

h

21. Are there any studs that must be removed from the cylinder head?

h Yes  h No

If yes, are they pressed in or threaded? h Pressed h Threaded Use the proper procedure to remove the studs. 22. Remove any core plugs that may be installed into the head.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

431

JOB SHEET

57

CYLINDER HEAD CRACK DETECTION Upon completion of this job sheet, you should be able to use two different methods to determine if a cylinder head is cracked. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: B.1. Remove cylinder head; inspect gasket condition; install cylinder head and gasket; tighten according to manufacturer’s specifications and procedures. B.2. Clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish; check passage condition. Tools and Materials • Technician’s tool set • Magnaflux crack detection kit (magnetic particle) • UV light penetrating spray crack detection kit Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

1. Clean the cylinder head with a parts washer or solvent. Disassemble and remove any components from the cylinder head. It should be bare when inspecting for leaks. Note: Steps 2–4 are for iron cylinder heads using the magnaflux method (magnetic particle).

h

2. Apply the powder from the kit in one area of the head. Try to limit the application to one cylinder and on one side of the head (e.g., try to apply it to the valve seat area for one cylinder).

h

3. After the powder is on the area to inspect, attach the magnet to go across the area. Turn on the magnet after it is positioned. If there is a crack, it will show up because the powder will collect in the crack. Rotate the magnet to different positions. Sometimes the crack will be visible only when the magnetic force is in a certain direction. Describe what you found. _________________________________________________________________________ _________________________________________________________________________ 4. After inspecting the entire cylinder head, clean the powder off by washing it. Note: Steps 5–8 are for aluminum cylinder heads using the penetrating spray and UV light method.

h

5. With the cylinder head clean and dry from a normal parts washing method, apply the special cleaner spray that is included in the kit. Allow the area to dry.

h

6. Next spray the penetrant dye onto the area, and allow it to dry for a few minutes (look in the directions of the kit for specific time measurement).

h

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Chapter 9

7. Next spray the developer from the kit onto the area. Use the UV light provided in the kit, and check for cracks. Describe what you found. _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

MEASURING CYLINDER HEAD WARPAGE Upon completion of this job sheet, you should be able to measure the warpage of a cylinder head. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.2. Clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish; check passage condition. Tools and Materials • Technician’s tool set • Straightedge • Feeler gauge Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure 1. Make sure the cylinder head gasket surface areas are thoroughly cleaned. Using the service manual, what is the specification for the maximum cylinder head warpage? _________________________________________________________________________ 2. Using the straightedge and feeler gauge, measure and record the maximum warpage of the cylinder head in several different directions and locations, following the service manual procedures. What is the maximum amount of warpage that you measured? _________________________________________________________________________ 3. Perform the same measurement and technique on the intake and exhaust gasket surfaces. What is the maximum amount of warpage that you measured? _________________________________________________________________________ 4. Based on your inspection and measurement, what services do you recommend? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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433

JOB SHEET

58

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

MEASURING VALVE-STEM-TO-GUIDE CLEARANCE Upon completion of this job sheet, you should be able to measure and inspect the ­valve-stem-to-guide clearance and determine what repair method should be used. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: B.9. Inspect valve guides for wear; check valve-stem-to-guide clearance; determine necessary action. Tools and Materials • Expanding small hole gauge • Outside micrometer Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure 1. Using the service manual as a guide, what is the maximum valve-stem-to-guide clearance specification? _________________________________________________________________________ 2. With the valves removed, insert the expanding small hole gauge into one valve guide in three areas (top, bottom, and middle). After removing the small hole gauge, use the outside micrometer to measure the dimensions and record them below. You are actually measuring the inside diameter of the valve guide. Position

I.D. of Valve Guide

Top Middle Bottom

3. Using the outside micrometer, measure the outside diameter of the valve stem (that came from that valve guide) in the same three places (top, middle, bottom) that you measured for the guide in step 2. The valve usually has a shiny wear pattern that will help you see where to measure the top, middle, and bottom. Position

O.D. of Valve Stem

Top Middle Bottom

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JOB SHEET

59

436

Chapter 9

4. Now calculate the difference in the inside and outside diameters from steps 2 and 3. The maximum of the three numbers is the actual valve-stem-to-guide clearance. Circle the maximum. Position

Difference between I.D. of Guide and O.D. of Stem

Top Middle Bottom

5. Compare the measurements from step 4 to the manufacturer’s specification. If it is outside of the manufacturer’s specifications, describe the repair procedure that must be used. Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

437

JOB SHEET

60

VALVE SEAT GRINDING Upon completion of this job sheet, you should be able to resurface the valve seat properly. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: B.10.

Inspect valves and valve seats; determine needed action.

Tools and Materials • Valve seat grinding stones • Valve seat grinder • Valve seat concentricity tool Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Describe the type of valvetrain in the engine: ______________________________________________________________________________ Procedure

Task Completed

Using the cylinder head(s) that you removed from the engine and the proper service ­manual, you will identify and perform the required steps to resurface the valve seat. 1. What are the valve seat angles for your cylinder head? Intake _______________ Exhaust _______________ 2. What is the angle needed to throat the seat? Intake _______________ Exhaust _______________ 3. What is the angle needed to top the seat? Intake _______________ Exhaust _______________ 4. Select the correct size and grit of stones required. Select the stones required for the seat, for topping, and for throating.

h

5. Thread each stone onto a stone holder.

h

6. Dress each stone.

h

7. Select the proper size pilot, and pass it through a cloth saturated with oil.

h

8. Insert a pilot into each of the valve guides by pushing it down while twisting it until it is firmly wedged in place. The pilot should extend at least 2½ inches (63.5 mm) from the seat to fit inside the stone holder.

h

9. Locate the lifting spring over the pilot. Lubricate the pilot with a few drops of motor oil.

h

10. Place the stone holder, with the proper stone for the seat, over the pilot. Check its fit onto the seat.

h

11. Attach the driver motor to the holder.

h

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Chapter 9

Task Completed 12. With the stone off of the seat, turn on the motor and work the stone into the seat. When working the grinding stone, lift it on and off the seat at a rate of 120 times per minute to prevent excessive pressures on the stone and seat.

h

13. Remove only enough material to provide a new surface all around the seat.

h

14. Use a scale, and measure and record the width of the seat. _________________________________________________________________________ 15. Top and throat the seat as needed to obtain the proper seat width.

h

16. Check valve seat concentricity by placing the fixture over the guide pilot. Specification _______________ Actual _______________ 17. Check the fit of the valve into the seat by coating the face with a light layer of Prussian blue and then placing the valve into the seat.

h

18. Rotate the valve back and forth 1/4 turn while applying pressure to the center of the valve. A small suction cup can be used.

h

19. Remove the valve, and inspect the contact pattern on the valve face and seat. Where is the contact located? _________________________________________________________________________ 20. What action is required to correct the contact? _________________________________________________________________________ 21. Repeat for all valve seats.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Cylinder Head Disassembly, Inspection, and Service

Name ______________________________________

Date __________________

439

JOB SHEET

61

RECONDITIONING VALVES Upon completion of this job sheet, you should be able to recondition the valves properly. Tools and Materials • Valve refacing equipment Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Using the cylinder head(s) that you removed from the engine and the proper service ­manual, you will identify and perform the required steps to recondition the valves. 1. What is the specified face angle for the valves? Intake _______________ Exhaust _______________ 2. Does the manufacturer recommend an interference angle?

h Yes  h No

3. Set the spindle head to the specified angle. Lock into place.

h

4. Dress the stone with a diamond tool.

h

5. Clamp the valve into the spindle chuck. What special concerns must you be aware of when setting the stem depth into the chuck? _________________________________________________________________________ _________________________________________________________________________ 6. Set the stroke length. What special concerns are associated with this step?

h

7. Correctly position the valve face and the stone.

h

8. Advance the stone into the valve slowly until light contact is noted. Begin to stroke the valve across the stone.

h

9. Note the micrometer reading. _________________________________________________________________________ 10. Continue to dress the face, feeding it 0.001 inch (0.25 mm) per pass until the face is clean.

h

11. Note the micrometer reading. _________________________________________________________________________ 12. What was the total amount of face material removed? _________________________________________________________________________ 13. Measure and note the valve margin. _________________________________________________________________________ Is the margin still within specifications? h Yes  h No If no, what must be done? _________________________________________________________________________

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Chapter 9

Task Completed 14. Use a piece of emery cloth to break the margin.

h

15. Measure and note valve head runout. Specification _______________ Actual _______________ 16. Inspect the valve face. Report any defects to your instructor.

h

17. Remove the valve from the spindle chuck, and set it into the valve stem holding fixture.

h

18. Dress the stone used to grind the valve stem.

h

19. How much material needs to be removed from the tip of the stem? _________________________________________________________________________ 20. Why is it important to stem the valve? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 21. Stem the valve, followed by chamfering the tip.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 10

VALVETRAIN SERVICE

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■

■■ ■■

■■ ■■

How to inspect the camshaft for straightness. How to measure the camshaft lobes and journals and determine needed repairs. How to inspect solid and hydraulic ­lifters and determine needed repairs. How to perform the leak-down test on hydraulic lifters and accurately interpret the results. How to inspect the pushrods and ­determine needed repairs. How to describe the methods used to correct rocker arm geometry.

■■ ■■ ■■ ■■ ■■ ■■ ■■

How to recondition rocker arms and replace studs. How to evaluate and measure valve springs. How to adjust the valvetrain during installation of hydraulic lifters.

Basic Tools Basic mechanic’s tool set Service manual

How to adjust valve clearances on engines using mechanical lifters. How to properly reassemble the ­cylinder head. How to install a cylinder head. How to replace valve seals with the ­cylinder head installed on the engine.

Terms To Know Base circle Camshaft Duration Heel Leak-down Lifter

Lobe lift Nose Open pressure Overlap Pushrods Rocker arm

Seat pressure Spring free length Spring shims Spring squareness

INTRODUCTION The valvetrain works to open and close the valves at the proper time. As the engine is run, the components of the valvetrain wear and stretch, causing the valve opening to be altered. This chapter discusses the methods used to inspect and repair the valvetrain, reassemble the cylinder head, adjust the valves, diagnose a failed head gasket, and replace worn valve stem seals on the car. Remember, before deciding to rebuild components such as camshafts and lifters, the cost of rebuilding components must be compared to the cost of replacing them. These components can usually be purchased new at less expense than rebuilding; however, there may be instances when rebuilding is a viable option.

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442

Chapter 10

INSPECTING AND SERVICING THE VALVETRAIN The camshaft, lifters, rocker arms, and pushrods work together to open and close the valves. If any of these components are worn or damaged, valve operation is adversely affected.

Removing and Replacing the Camshaft, OHV Engines

Caution Inadequate camshaft bearing or lobe lubrication may cause damage during the first few seconds of engine operation.

Before removing the camshaft on an OHV engine, the timing chain and camshaft sprocket must be removed, as we’ll discuss in the next chapter. The rocker arms, pushrods, and valve lifters must be removed so the valve lifters do not interfere with the camshaft removal. Other components driven by the camshaft, such as the oil pump and/or distributor, must be removed prior to camshaft removal. On a rear-wheel-drive (RWD) vehicle with the engine in the vehicle, the radiator usually has to be removed to allow camshaft removal. After these components are removed, the camshaft may be removed from the front of the engine. All the camshaft journals and lobes must be thoroughly lubricated with the engine manufacturer’s specified oil or an approved prelubing compound before installing the camshaft. The camshaft bearings must also be well lubricated. Install the camshaft in the camshaft bearing openings. Hold the camshaft in a horizontal position during installation, and avoid scraping the cam lobes across the bearings, which results in bearing scratches. After the camshaft is installed, the valve lifters, pushrods, and rocker arms may be installed, followed by the oil pump and distributor. Install the camshaft sprocket and timing chain, and be sure the camshaft is properly timed to the crankshaft. Install the other components that were removed to gain access to the timing chain and sprocket. Be sure all fasteners are tightened to the specified torque.

Removing and Replacing the Camshaft, OHC Engines Read through the service information for the vehicle you are working on before attempting to remove the camshaft from an overhead camshaft engine. Often there are special tools or procedures that can make your work both safe and efficient. The following procedure outlines the steps required to remove the camshafts on a late-model Asian overhead camshaft V6 engine:

1. Remove the valve covers. 2. Rotate the engine to top dead center (TDC) firing on cylinder number 1. 3. Remove the camshaft sprocket bolts, but do not disturb the sprockets. 4. Install the sprocket holding fixtures in between the camshaft sprockets, and remove the sprockets from the camshafts. 5. Loosen the camshaft cap retaining caps in stages, following the proper sequence. Failure to do so can break the camshaft. 6. Remove the camshafts, and inspect them thoroughly. 7. Remove and label the rocker arms, if needed, to be able to reassemble them in their original positions.

Removing Camshafts and Rocker Arms, DOHC Engine Before removing the camshafts on a DOHC engine, the timing belt must be removed, as we’ll discuss. Follow this procedure to remove the camshafts: 1. Remove the pulley to camshaft retaining bolts on each camshaft, and remove the camshaft pulleys (Figure 10-1). Identify each pulley so it is reinstalled in the ­original location. 2. Identify all camshaft holder plates and camshaft holders so they will be reinstalled in their original locations. Loosen the rocker arm locknuts and adjusting screws, Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service



and then remove the retaining bolts in the camshaft holder plates and camshaft holders (Figure 10-2). 3. Remove the camshafts from the cylinder heads. 4. Place an elastic around each triple set of rocker arms to keep them together. Identify all rocker arm sets or lay them out in order after removal, because they must be reinstalled in the original positions. 5. Remove the rocker shafts from the cylinder heads toward the transmission end of the engine (Figure 10-3). 6. Remove the rocker arm sets from the cylinder head. Camshaft holder plate Camshaft holders

Camshaft sprockets

Retaining bolts Oil seal

Figure 10-1  Removing the camshaft pulleys.

Figure 10-2  Removing camshaft holder and holder plates.

Rubber band

12-mm bolt

Rocker arm assembly

Figure 10-3  Removing rocker arm shafts.

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444

Chapter 10 Plastigage strip

Plastigage measure

Figure 10-4  Measuring camshaft end play.

Special Tools Outside micrometer V-blocks Dial indicator Pushrod adapter

Figure 10-5  Measuring camshaft bearing clearance.

Measuring Camshaft End Play and Camshaft Bearing Clearance, DOHC Engine Follow these steps to measure the camshaft end play:

The camshaft contains a group of lobes that open and close the intake and exhaust valves at the correct time. Duration is the number of degrees that a cam lobe holds a valve open. Overlap is the number of degrees that the crankshaft rotates when both intake and exhaust valves are open near TDC on the exhaust stroke. The nose is the area just before and after the peak of the lobe. The camshaft heel is 180 degrees from the lobe high point. This is where the valve will be closed.

Classroom Manual Chapter 10, page 201

1. With the rocker arms removed, place the camshafts in their original positions on the cylinder head. Be sure the camshaft journals and bearing surfaces are clean. 2. Place a light coating of the engine manufacturer’s specified oil on the camshaft holder and holder plate bolt threads. Install the camshaft holders, holder plates, and retaining bolts. Tighten these bolts in the proper sequence to the specified torque. 3. Mount a dial indicator so that the indicator stem contacts the front of the camshaft (Figure 10-4). With the camshaft pushed rearward, zero the dial indicator. 4. Pull the camshaft forward, and read the end play on the dial indicator. 5. Remove the camshaft holder plates and holders, and place a plastigage strip across each camshaft journal. 6. Install the camshaft holders and holder plates, and tighten the retaining bolts in the proper sequence to the specified torque. 7. Remove the camshaft holders and holder plates, and measure the plastigage width to determine the camshaft bearing clearance (Figure 10-5). 8. If the camshaft bearing clearance is more than specified, and the camshaft has been replaced, the cylinder head must be replaced. If the camshaft has not been replaced, remove the camshaft, and measure the camshaft runout. If the runout is within specifications, replace the cylinder head. When the runout is not within specifications, replace the camshaft, and recheck the bearing clearance.

Inspecting the Camshaft Thorough inspection of the camshaft is important due to the many factors that apply to valve operation and ultimately engine performance. These factors include lift, duration, and overlap. The proper relationship among these three aspects of the camshaft can be maintained only if the lobes are not worn (Figure 10-6). Begin camshaft inspection with a visual inspection of the lobes and journals. Both of these must be free of scoring and galling. Normal lobe wear is a pattern slightly off center, with a wider wear pattern at the nose than the heel (Figure 10-7). The off-center wear is a result of the slight taper (0.0007 to 0.002 inch) of the lobe used in conjunction with

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Valvetrain Service

445

Lobe-separation angle (lobe centers)

Overlap TDC

Exhaust closed

Intake opens

Lift

Lift

Intake duration

Exhaust duration

Intake lobe

Exhaust lobe

Intake closed

Exhaust opened

Figure 10-6  Wear on the camshaft lobe can affect several factors of valve timing and duration.

Normal wear pattern wide at nose of lobe and narrow toward heel Lifter Nose Lobe Crown

Base circle

Taper Heel Abnormal wear pattern extends across to the edges of the lobe

Figure 10-7  Normal wear patterns are slightly off center on the lobe.

the convex shape of the lifter to rotate the lifter. If the wear pattern extends to the edges of the lobe, the lifter will not rotate. If there is any scoring or galling, the camshaft will have to be replaced or reconditioned. Also inspect the fuel pump eccentric and distributor drive gear (if equipped). The camshaft lobe lift can be measured using an outside micrometer. Lift is determined by measuring the lobe from heel to nose and subtracting the base circle measurement from the initial measurement (Figure 10-8). Another method is to install the camshaft onto V-blocks and use a dial indicator to measure the amount of lift. Locate the

The camshaft base circle is the diameter across the sides of the camshaft lobe with the lobe facing upward.

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Chapter 10 Duration

Nose Flank area

Flank area

B

A

Base circle Heel

Figure 10-8  Determining camshaft duration.

plunger of the indicator on the heel of the lobe, and zero the indicator. Rotate the camshaft until the highest reading is observed. This is the amount of lobe lift. Check camshaft straightness before checking lift in this manner. SERVICE TIP  Worn camshaft lobes may cause a heavy clicking noise at 1,500 rpm to 2,000 rpm.

Lobe lift is the distance that a cam lobe moves the contacting valvetrain component as the cam lobe rotates.

Camshafts with high durations cannot be measured using a micrometer, since a true base circle measurement will not be obtainable. This is due to the ramps beginning more toward the heel. In these instances, use a dial indicator to measure the lift of the pushrod. Another method of measuring lobe lift involves installing the camshaft into the engine block with the lifters and pushrods. A special cup-shaped adapter is installed onto the dial indicator to accept the pushrod (Figure 10-9). With the pushrod at its lowest point of travel, zero the dial indicator. Continue to rotate the camshaft until the maximum amount of deflection of the dial is observed. This represents the total lift of the camshaft. Measure the camshaft journals for size, taper, and out-of-round using an outside micrometer (Figure 10-10). Most overhead valve engines have different size journals, with the largest being toward the front of the engine. This is done to make camshaft removal and installation easier. To determine the amount of out-of-round, measure each journal in two different directions and compare to specifications. Also check for journal taper by measuring at each end of the journal (Figure 10-11). Once the new camshaft bearings are installed into the engine block, the clearance can be determined. The bearings may need to be honed to obtain the required clearance. This will not be possible if the journals are worn beyond limits. Camshaft straightness can be checked by placing it in V-blocks. The camshaft is supported in the blocks by the journals on both ends. Install a dial indicator onto the central journal (Figure 10-12). Observe the dial indicator as the camshaft is rotated. A total indicated reading (TIR) of 0.002 inch (0.050 mm) indicates excessive warpage. With the camshaft set up to measure straightness, also check base circle runout. Locate the dial indicator plunger on the heel of the lobe, and zero the gauge. Slowly rotate the camshaft until the lowest gauge reading is obtained. This is the point where the camshaft lobe ramp starts. Note this reading; then rotate the camshaft in the opposite

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Pushrod

Camshaft journals

Figure 10-9  Using a special adapter to measure OHV camshaft lobe lift with the camshaft installed in the engine.

Figure 10-10  Worn camshaft journals can cause reduced oil pressure.

Rotate camshaft while measuring

Figure 10-11  Compare each journal to specifications and check for taper while inspecting the lobes for wear.

Figure 10-12  Measuring camshaft warpage.

direction until the gauge indicates the start of the other ramp. As a rule, total runout should not exceed 0.001 inch (0.025 mm). If the runout is excessive, the lifters may pump up when the valve is closed.

INSPECTING AND SERVICING VALVETRAIN COMPONENTS, OHV ENGINE Inspecting the Lifters Inspect the camshaft contact surface or face of the lifter. It must be smooth, with a centered circular wear pattern. To reduce wear, the lifter rotates in its bore. Part of this ­rotating action is accomplished by a convex contour machined in the face. If the wear extends to the edge of the face, it indicates that the lifter is flat or concave. If the wear pattern runs across the lifter face, it indicates that the lifter was stuck in its bore. Lifter crown can be checked by laying a straightedge across the face. If the straightedge does not rock, the lifter must be replaced.

Valve lifters are sometimes called tappets because of the sound they make during operation, especially if they are loose.

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Caution If it is determined the camshaft requires replacement, always replace the lifters. The camshaft and lifters become wear mated within a short time, and used lifters will rapidly wear a new camshaft. It is possible to replace a single lifter without replacing the camshaft. Leak-down is the relative movement of the plunger in respect to the lifter body.

Classroom Manual Chapter 10, page 206

Special Tools Leak-down tester Special tester fluid

Roller lifters may degrade over time if the engine’s lubrication system is not properly maintained. This can be inspected by looking for wear patterns and grooves on the roller itself. It may also cause low engine rpm misfires due to the lifter not operating smoothly and lifting the valve properly. Displacement on demand (active fuel management) lifters require great lubrication system maintenance. An improper viscosity oil or worn-out oil will cause engine operation issues and diagnostic trouble codes (DTCs) will be stored in the computer. The lifter body should be polished and absent of any signs of scoring or scuffing. The pushrod seat should be polished and smooth. If the seat shows signs of a ridge, the lifter must be replaced. Hydraulic lifters passing visual inspection should be tested for leak-down. A special leak-down tester is used for this operation (Figure 10-13). Test results are determined by the length of time, in seconds, required before the tester overcomes the hydraulic pressures in the lifter. Normal leak-down range is between 20 and 90 seconds. Always refer to the manufacturer’s specifications. A lifter that fails the first leak-down test should be retested, since air may be trapped in it. If the test results indicate a failure or marginal results, replace the lifter. To perform a leak-down test: 1. Fill the cup with enough fluid to cover the lifter, and place the lifter into the fluid. 2. Position the tester ram into the pushrod seat of the lifter, making sure that the ram is centered. 3. Adjust the ram length until the pointer aligns with the set mark on the lever, and tighten the jam nut. 4. Pump the weight arm to move the lifter plunger through its entire range of travel. This is done to purge air from the lifter. Continue to pump the lifter until a resistance is felt. 5. Raise the arm to return the lifter to its full height; then lower the ram onto the pushrod seat. Time how long it takes for the weight to compress the lifter. During this test, turn the hand crank on the tester so the cup rotates at a rate of one turn every 2 seconds. Roller lifters are inspected in the same manner. The roller must be smooth and cannot be twisted to the body. In addition, inspect the mechanism used to prevent lifter rotation. The lifter must be parallel to the camshaft lobe at all times. To prevent rotation, some Weighted arm Pointer

Ram Handle

Cup

Figure 10-13  Using a special lifter leak-down tester to determine lifter condition.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service Oil hole

Metering valve

Retainer Ball

Lifter body

Plunger spring

449

Lock ring

Plunger Spring

Pushrod seat

Figure 10-14  Internal components of a hydraulic lifter.

manufacturers use a pivot link between two lifters, while others use some type of lock. These mechanisms cannot have any twist in them. If the lifters are to be reused, it is important to maintain their original positions on the camshaft. When a lifter is determined unserviceable, replace the set. Also, replace the camshaft whenever the lifters are replaced. Make sure the replacement lifters have the same body diameter, operating height, oil groove position, and oil groove width as the original equipment lifters. It may occasionally be necessary to disassemble a hydraulic lifter to clean it or to inspect it. If this is necessary, disassemble one lifter at a time and pay attention to the order of the check valve assembly. Lifter disassembly is done by pressing down on the pushrod seat with your thumb and using a screwdriver to remove the snap ring. Remove the plunger from the body; this may require tapping the body. Next, remove the check valve assembly. After thoroughly cleaning the lifter components in solvent, visually inspect them for signs of wear. If the internal components pass inspection, the lifter can be reassembled (Figure 10-14). During reassembly, cleanliness of the parts is of utmost importance. SERVICE TIP  Worn or sticking valve lifters may cause a clicking noise at low speed, especially when the engine is warming up.

SERVICE TIP  It is common practice to replace the valve lifters during an engine overhaul or if one or more lifters fail. This is insurance against a failure shortly after significant labor costs were charged to the customer. Lifter leak-down is still commonly performed on heavy-duty or specialty applications, but it is not common in the general repair shop.

Inspecting the Pushrods Inspect pushrods for wear and bending. Any pushrod failing inspection must be replaced. Visually inspect the two tip surfaces for wear. Normal wear results in a smooth and polished finish. Wear on the side of the pushrod indicates that the pushrod guide is defective and it, too, must be replaced. Finally, check the pushrod for warpage by rolling it on a sheet of glass or using a special fixture (Figure 10-15). Total pushrod runout should be less than 0.003 inch (0.08 mm). On hollow pushrods, clean the oil passage with a piece of wire and solvent. The oil passage opening should be circular and have a well-defined edge. If the hole is oval shaped or the edge is chamfered, replace the pushrod.

Caution Wear safety glasses when disassembling lifters; components may spring out under pressure.

On OHV engines, ­pushrods connect the valve lifters to the rocker arms.

Special Tools Pushrod tester Dial indicator Sheet of glass

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Chapter 10 Pushrod

50 40

40 30

30

20

20 10

_

0+

10

Holding fixture

Dial indicator

Figure 10-15  A special fixture used to measure warpage of the pushrod.

Inspecting and Servicing Rocker Arms and Shafts When rocker arms are removed, always set them out in order so they can be installed in their original positions. Inspect all rocker arms for wear in the pushrod contact area, the tip that contacts the valve stem, and the bore in the center of the rocker arm. A slight amount of wear on the end of the rocker arm that contacts the valve stem may be removed with a valve grinding machine. A special attachment on these machines is available for rocker arm resurfacing. Do not remove excessive material from the rocker arm, because this action changes the rocker arm geometry. Rocker arm wear in the pushrod contact area or in the bore requires rocker arm replacement. SERVICE TIP  Worn valvetrain components, such as rocker arms, shafts, and pushrods, cause valvetrain noise.

On individual rocker arms, inspect the rocker arm for wear in the pivot contact area. Wear in this area requires rocker arm replacement. Worn pivots must also be replaced. Inspect all rocker arm shafts for wear, scoring, cracks, blocked oil passages, and a bent condition. If these conditions are present, replace these shafts. Use shop air pressure and an air gun to blow out all oil passages in the rocker arms and shafts. Be sure the oil passages in the cylinder head that supply oil to the rocker arms and shafts are not restricted. If the oil for the rocker arms is supplied through the pushrods, be sure all the pushrod oil passages are not restricted.

REPLACING ROCKER ARM STUDS If the threaded stud has a jamming shoulder, the boss does not require milling.

Special Tools Stud puller Milling tool Tap set

If any of the rocker arm studs are damaged, worn, or loose in the cylinder head, they must be replaced. Broken or damaged press-in studs can be replaced by pulling the original stud and replacing it with a standard press-in stud. If the original press-in stud is loose, the technician can oversize the hole and install oversize studs. Press-in oversize studs are available in 0.006, 0.010, and 0.015 inch oversize. If desired, it is possible to replace press-in studs with threaded studs. Begin by removing the original studs using a stud puller (Figure 10-16). If the new stud has a jam nut, the stud boss height must be reduced the same amount as the height of the nut. Use a milling tool to remove the required amount of material. The stud boss is ready to be tapped to accept the new threaded stud.

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Valve tip

Pushrod socket

Puller in use

Fulcrum

Figure 10-16  Using a stud remover to pull a rocker stud.

Figure 10-17  The three wear areas of the rocker arm.

The rocker arm is constructed of cast iron, stamped steel, or aluminum. The contact areas with the pushrods and valve stems are usually hardened. Regardless of the type of mounting used by the manufacturer, all rocker arms must be inspected for wear at the three high-stress areas. These areas are the pivot, pushrod contact, and valve stem contact surfaces (Figure 10-17). The pushrod contact area of the rocker arm should be round and the wear even. Normal wear will result in a shiny surface. A ridge buildup around the pushrod contact area indicates the rocker was hammering or too much valve lash. Pits, scores, and galling generally indicate lack of lubrication or excessive heat. Valve stem wear should be centered in the arm. If the wear is not centered, the rocker arm pivot may be worn or the stud may be bent. If these are good, then carefully inspect the valve guide and seat for wear. In addition to these checks, inspect the side of the rocker arm for any indications of cracks. Pay close attention around the pivot contact area. Stamped steel rocker arms are not resurfaceable and should be replaced if found to be worn. The method the manufacturer uses to mount the rocker arm will require unique inspection procedures. Following are some of the additional inspections that should be made based on the type of mounting:

Classroom Manual Chapter 10, page 210

Special Tools Sheet of glass Outside micrometer Bore gauge

1. Shaft-mounted rocker arms are located on a heavy shaft running the length of the cylinder head (Figure 10-18). The shaft is supported by stands. Inspect it for wear on the shaft where the rocker arm pivots. The shaft should be free of scoring or galling. Normal wear is indicated by a slight polishing but no ridges. Wear in this location is usually due to lack of lubrication or excessive heat. Also check the shaft for warpage by simply rolling it on a flat surface (such as a sheet of glass). Shaft-to-bore clearance can be checked by using an outside micrometer to measure the diameter of the shaft where the rocker rides. Use a bore gauge and zero it to the micrometer (Figure 10-19). Insert the bore gauge into the rocker arm, and note the dial reading. Out-of-round can be checked at the same time as clearance by measuring in at least two directions. Compare the results to specifications. If wear is excessive, the rocker arm must be replaced. Typical oil clearance specification is a maximum of 0.005 inch (0.13 mm). Visually inspect the springs and spacers used to separate the rocker arms for warpage, breakage, scoring, and other types of unusual wear patterns. Replace any when it is found to be defective or worn. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10 Bore gauge

Micrometer

Figure 10-18  Shaft-mounted rocker arms.

Figure 10-19  Shaft-to-bore clearance and taper can be checked by using an outside micrometer set to the size of the rocker arm shaft and then zeroing the small bore gauge to the micrometer.

2. Stud-mounted rocker arms use a split ball for the pivot point of the rocker arm (Figure 10-20). Pedestal-mounted rocker arms are similar to the stud-mounted assembly, except the rocker pivots on a split shaft (Figure 10-21). With both of these styles, the pivot fulcrum must be inspected for wear. Look for nicks, scoring, or scuffs. If the pivot or rocker arm is worn in these areas, replace both components. Scoring or scuffing indicates a lack of lubrication. Stud-mounted rocker arms can be lubricated through a hollow pushrod or by small holes drilled through the mounting stud. Pedestal-mounted rocker arms are usually lubricated by oil passing through a hollow pushrod. If poor lubrication is suspected, the stud should be replaced.

Rocker arm bolt Rocker arm stud nut

Rocker arm

Fulcrum seat Rocker arm

Fulcrum

Rocker arm ball stud

Figure 10-20  Stud-mounted rocker arm.

Figure 10-21  Inspect the pivot fulcrum and contact surface for nicks, scoring, or scuffing.

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Shorten valve or lengthen pushrod. Rocker arm high position 50 percent open Small fractures

Figure 10-22 Inspect the stud nuts for wear or damage.

Rocker arm low position

If valve is short, remove material and shorten pushrod or adjust clearance.

If valve is long, add shims and lengthen pushrod or adjust clearance.

Add to stem length or shorten pushrod.

Figure 10-23  Methods of correcting rocker geometry.

On positive stop rocker-arm stud nuts, check the shoulder for ­damage or fractures (Figure 10-22). Also check the rocker arm’s contact surface with the pivot fulcrum. If the pivot or rocker arm is worn in this area, replace both components. The follower may have a flat pad, sliding pad, or rollers where it rides against the camshaft lobe. This area must be visually inspected for wear. Check the rest of the follower much like the rocker arm. SERVICE TIP  If the engine is equipped with stamped steel rocker arms, it is a good practice to replace them during a rebuild. The cost of these components is very low and can be considered inexpensive insurance.

Rocker arm studs may pull out of the head or wear from contact with the rocker arm. Inspect the stud very closely. If it is loose, install a new stud.

Correcting Rocker Arm Geometry If the rocker arm is not contacting the valve stem tip in its center at 50 percent valve opening, the valve guide will be exposed to excessive side thrust. To correct rocker arm geometry, one of the following methods can be used (Figure 10-23): ■■ Changing the length of the pushrod ■■ Machining or shimmying the rocker arm stand ■■ Correcting valve stem height

The rocker arm is a pivoting lever used to transfer the motion of the pushrod to the valve stem.

Inspecting and Servicing Rocker Arms and Shafts, DOHC Engines

Classroom Manual Chapter 10, page 210

Inspect the contact pad on all rocker arms for scoring and wear. Shafts that are visibly worn and/or scored must be replaced. Measure the rocker arm shaft diameter with a micrometer in the first rocker arm position on one end of the shaft. Install a bore gauge in the micrometer with the micrometer set at the rocker arm shaft diameter, and zero the bore gauge (Figure 10-24). Install the bore gauge in the matching rocker arm opening, and determine the rocker arm to shaft clearance by reading the amount the gauge pointer moved from the zero position (Figure 10-25). Repeat this procedure for all the rocker arms. Replace any rocker arms and shafts if this clearance is not within specifications. SERVICE TIP  If correction is done by milling or shimming the rocker arm stand, alter the stand height one-half the total amount needed at the stem tip.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Bore gauge

Push

Measure rocker arm bore.

Micrometer

Figure 10-24  Transferring rocker arm shaft diameter reading from a micrometer to a small bore gauge.

Inspect rocker arm face for wear.

Figure 10-25  Measuring rocker arm bore.

Hydraulic lifter assembly

Figure 10-26  Testing a hydraulic lifter for resistance.

Inspect each lost motion assembly for scoring or wear. Replace all scored or worn assemblies. If the lost motion assembly bores in the cylinder head are scored, replace the cylinder head. When the lost motion assembly protrusion is pressed gently with finger pressure, it should sink slightly (Figure 10-26). Increasing the force on the protrusion should result in further sinking. If any lost motion assembly does not move smoothly when finger pressure is applied to the protrusion, replace the assembly.

Valve Springs Spring squareness refers to how true to vertical the entire spring is. A warped spring will cause valve stem and guide wear.

Begin valve spring inspection with a visual inspection. If a spring is broken or obviously shorter than the others, replace it (Figure 10-27). In addition, look for cracks, excessive corrosion, pitting, and nicks. If a valve spring has any of these defects, replace it. If the spring passes visual inspection, other checks are required before reusing it. These checks include spring squareness, free length, valve close pressure, and valve open pressure.

Figure 10-27  Any valve springs that are below free height specifications must be replaced. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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2

3

Valvetrain Service

Check specification.

Closed end downward

Figure 10-28  Spring squareness can be checked by placing the spring next to a square and rotating the spring.

A spring that is not square can cause excessive side pressure on the valve stems. This pressure can cause wear or stress on the stem, guide, and valve seat. The spring free length of the spring must be checked and compared to specifications. Valve springs below the minimum length indicate weak springs. Valve springs under the specified height may be the result of excessive heating. Check the cylinder head and valves for other indications of overheating. Springs that are below the specified height can cause burned or floating valves. Also, the valve spring free length should not vary more than 1/32 inch (0.8 mm) between springs. It may be possible to use spring shims to correct for spring height instead of replacing the spring. To inspect the valve spring for squareness and free length, place the spring next to a square and rotate it (Figure 10-28). Watch for any warpage of the spring as evidenced by a gap between the top of the spring and the square. A general rule is the spring should not have more than a 2.3-degree angle. The gap between the spring and square will be different based on the length of the spring. For this reason, general specifications for all springs should be avoided. The basic formula for determining gap is. SERVICE TIP  Rocker arms must be replaced in sets of three.

Spring length 3 0.039 5 Maximum gap

Spring free length is the height at which the spring stands when not loaded. Spring shims are used to correct the installed height of the valve spring. Details concerning shim use and selection are provided later in this chapter.

Classroom Manual Chapter 10, page 212

Special Tools Square Machinist’s rule Spring tension tester Torque wrench

where 0.039 is the product of 2.3 times 0.017 (the maximum amount of gap allowed per degree per inch). For example, if the spring free length is 2 inches, the maximum gap would be 2 3 0.039 5 0.078 inch. To convert to metric measurements, use spring length times 0.43 5 maximum gap in mm. While checking squareness, also note the length of the spring as it is rotated. The length should not vary by more than 1/32 inch (0.8 mm). If the spring is not square or free length is not within specifications, replace the spring. Valve closed and open pressures are tested using a special spring tension tester (Figure 10-29). It is possible for a spring to pass the free height check but fail the tension tests. This is due to changes in the metal structure as a result of temperature changes. Springs not within specifications must be replaced. Spring pressure is measured at the two lengths at which the spring operates: valve open and valve closed. To test the spring, begin by checking that the gauge reads zero. Place the spring onto the tester’s table. Pull down on the lever until the spring is compressed to the specified installed height as indicated on the scale. Read the pressure, Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Figure 10-29  Testing the valve spring for proper seat and open pressures.

Seat pressure indicates spring tension with the spring at installed height with the valve closed. Open pressure indicates spring tension with the spring compressed and the valve fully open.

indicated on the dial, required to achieve the specified height. Compare the dial reading with the manufacturer’s specifications. This reading provides the spring’s seat pressure (valve closed pressure). Next, compress the spring to the valve open height specification. This open pressure specification is determined by the maximum camshaft lift; for example, if the installed height specification is 1 13/16 inches and the cam lift is 7/16 inch, then compress the spring until the height of the spring is 1 3/8 inches. Compare the tension reading obtained at the valve open height to specifications. While maintaining the valve open height, check for coil bind by trying to insert a 0.010- to 0.012-inch (0.25- to 0.30-mm) feeler gauge between each coil. If the feeler gauge cannot fit between the coils, replace the spring. SERVICE TIP  Check new springs for squareness and warpage before installing them.

Repeat the pressure tests for all outer and inner valve springs. Remember that the inner spring rides on a stepped portion of the spring retainer, and you will have to allow for this; for example, if the step measures ⅛ inch, the inner spring must be compressed 1/8 inch more than the outer spring. Spring tension should be within 10 percent of the manufacturer’s specification, with no more than a 10-pound difference between springs. If the spring tensions are outside of specifications, the springs must be replaced. Another style of spring tension tester uses a torque wrench instead of a gauge (Figure 10-30). To adjust the table of this tool, turn it until the surface is in line with the specified height marked on the threaded stud (Figure 10-31). Make sure the zero mark is facing toward the front. Locate the valve spring over the stud on the table, and Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Set knob to compressed length of spring

457

Valve spring tester

Figure 10-30  Another style of valve spring tension tool uses a torque wrench instead of a dial to indicate pressures.

Figure 10-31  Adjust the table height to the installed height of the spring.

lift the compressing lever to reset the tone device. Install a needle- or dial-type torque wrench onto the tension tester. Compress the spring with the torque wrench until the ping is heard. Note the reading on the torque wrench. Spring tension is determined by multiplying the torque wrench reading by two. Valve open tension tests are performed in the same manner.

Caution Be sure all sealers used are oxygensensor safe. Some sealers will cause the sensor to fail.

CYLINDER HEAD REASSEMBLY The cylinder head is now ready for reassembly. Begin this procedure by replacing any studs removed during the reconditioning operation. Next, clean all oil galleys and coolant passages, and install the plugs. If the cylinder head uses a core plug to seal the back camshaft bore, do not install this plug until the camshaft is fitted. Coat threads with liquid pipe thread sealer or Teflon tape. Core and galley plugs are driven into the cylinder head using a special driver. Make sure to drive the plug in the correct direction. Coat the sides of the plug with a good water- and oil-resistant sealer. Be careful to keep any chemical sealers off the end of the plug where they can be washed into the engine oil. Start all plugs by hand, and then torque them to specifications. Most plugs use a taper pipe thread. These plugs will not fully seat until they are tightened.

Special Tools T-gauge Micrometer

Installed Spring Height Before installing the valves, polish the valve stems using a fine crocus cloth and solvent, and then thoroughly clean the valves again. Lubricate the valve stems with a generous amount of engine oil or assembly lube, and install the valves into their correct ports. After the valves are installed in the head, check spring height. This can be done without Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Valve spring retainer

Valve spring installed height

Measure from underside of retainer to spring seat.

Valve stem

Spring seat

Figure 10-32  Measuring valve spring installed height without the valve spring installed.

Figure 10-33  Measuring spring installed height.

installing the valve spring. Install the valve and the spring retainer; then measure the distance between the cylinder head and valve spring retainer (Figure 10-32). Stem height increases due to resurfacing the valve face and seat. Stem height is corrected by removing material from the stem tip. This operation restores the proper rocker arm geometry. However, the valve spring keeper grooves are higher from the valve spring seat now than they were originally. A telescoping gauge or vernier calipers can be used to check spring height (Figure 10-33). The valve retainer and keeper are installed without the valve spring to make this measurement. If the installed height is greater than specifications, select the correct shim to return the spring height to specifications. If the spring height measurement is greater than 0.060 inch (1.5 mm) over specifications, the valve seat will need to be replaced. To determine the shim size required, measure the installed height of the valve spring. Compare the measurement with specifications. If the measured distance is greater than specifications, subtract the measurement from the specifications to determine the difference. The difference is the correct size shim required.

Caution Use of shims in excess of recommendations will overstress the valve springs and overload the camshaft lobes. Shims should never be used to correct for a weak spring.

Installing Valve Stem Seals The point at which the valve stem seals are installed during reassembly of the head depends upon the type of seal. If the cylinder heads use positive lock valve stem seals, they may need to be installed prior to installing the valves. A seal installation tool is used for this purpose (Figure 10-34). Other types of positive seals are installed over the valve stems. Most manufacturers use different size seals for the intake valves than for the exhaust valves. The seals are usually color coded or identified in some manner. Always refer to the appropriate service manual to determine proper seal location. SERVICE TIP  A 0.015-inch (0.4-mm) shim increases spring pressure by 3 pounds (21 kPa), a 0.030-inch (0.8-mm) shim increases pressure by 6 pounds (42 kPa), and a 0.060-inch (1.5-mm) shim increases pressure by 12 pounds (83 kPa).

Installing Positive Stem Seals.  Many aluminum cylinder heads use a steel spring seat between the head and the valve spring (Figure 10-35). The seal must fit onto the seat properly. Fit the seat first; then install the seal. After all the seals are installed, place the cylinder head into a work stand for preparation for valve installation. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Valve keepers

Valve retainer Valve guide seal installer Valve spring

Valve seal

Valve spring Spring seat

Figure 10-34  Using a special tool to install the valve stem seal.

Figure 10-35  Many aluminum cylinder heads use a steel spring seat. Install the seat before installing the valve stem seal.

Following is a general procedure for the seals if the valve stem seal is to be installed over the valve stems: 1. If it has not already been done, polish the valve stem using a fine crocus cloth and solvent. Be sure to thoroughly clean the valve again before installing it. 2. Lubricate the valve stem with a generous amount of engine oil or assembly lube. 3. Install the valve into its correct port. 4. Place the plastic sleeve over the end of the valve stem to protect the seal as it is installed. The sleeve is included in the valve stem seal kit. 5. Place the seal over the stem, and slide it down until it contacts the top of the valve guide. 6. Use the installation tool to press the seal over the guide until it is flush with the top of the guide.

Special Tools Plastic sleeve Valve seal installation tool

Installing Umbrella-Type Seals.  Umbrella-type seals are installed after the valves are located into the cylinder head. Before installing the valve, polish the valve stem using a fine crocus cloth and solvent; then thoroughly clean the valve again. Lubricate the valve stem with a generous amount of engine oil or assembly lube, and install the valve into its correct port. Place the stem seal over the stem, and push it down until it touches the valve guide boss. There is no need for special tools or press fitting this type of seal. Installing O-Ring Stem Seals.  The O-ring seal is installed after the valve springs have been located over the valve stem and are compressed. With the spring compressed, install the seal into the bottom groove. It is a good practice to lubricate the seal with engine oil before installing it. Check the seal to make sure it did not twist during installation.

SERVICE TIP  If the special seal installation tool is not available, it may be possible to use a ⅝-inch-deep socket and a light hammer to drive the seal in place.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Installing the Valves, Springs, and Keepers

Caution Be sure to install the correct length of umbrella seal. If a seal that is too short is installed, the upand-down motion will create a pumping action. This will result in excess oil entering the combustion chamber.

If the cylinder head uses positive stem seals requiring installation prior to valve installation, press them onto the valve guide bosses at this time. Start at one end of the cylinder head and work toward the other, working with one valve at a time. The following general procedure can be used to install the valves into the cylinder head (Figure 10-36): WARNING  Wear approved eye protection when assembling the cylinder head. In addition, face the springs away from your body as they are being compressed.

1. Polish the valve stems using a fine crocus cloth and solvent. Be sure to thoroughly clean the valve again before installing it. 2. Lubricate the valve stems with a generous amount of engine oil or assembly lube. 3. Locate the valve into the correct port. Do not mix the valves. The valve should install easily into the guide. 4. Install the correct size spring shim with the serrated side resting against the cylinder head. 5. Install umbrella-type or positive-type valve stem seals (if equipped) over the valve stem. 6. Place the valve spring over the stem. When installing the valve spring, make sure it is facing in the correct direction. Variable rate springs are installed with the tightly coiled end of the spring face toward the head. If the valve spring has a taper, the larger end fits against the spring seat. 7. Locate the spring retainer over the valve spring. 8. Use an approved spring compressor to compress the valve spring (Figure 10-37). Compress the spring only enough to install the keepers. 9. If the cylinder head uses an O-ring-type valve seal, install it onto the bottom groove while the spring is compressed. 10. With the spring compressed, install the keepers (Figure 10-38). Make sure they are seated into their grooves before releasing the valve spring compressor. 11. With the head on a stand, tap the top of the valve stem with a plastic hammer (Figure 10-39). This is to ensure that the keepers are properly seated. 12. Attempt to turn the valve spring by hand. If it is properly installed, the valve spring should not rotate. 13. Repeat for all valves. Keepers (key must be set properly) Spring retainer Valve spring Valve stem seal

Cylinder head

Exhaust valve

Figure 10-36  Typical cylinder head assembly.

Intake valve

Figure 10-37  Compress the spring, and use a dab of grease to hold the keepers in place.

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Plastic mallet Valve keepers

Valve spring compressed

Valve stems

Figure 10-38  The spring must be compressed to install the keepers.

Figure 10-39  Tap the valve spring retainer with a plastic hammer to be sure that the keepers are fully seated.

14. Lubricate the stem tips with a multipurpose grease. 15. Install the rocker arms, fulcrums, or shafts. Do not tighten the rocker arm bolts at this time. In addition, it is a good practice to test the valve seat sealing after the valves are installed. To do this, install the spark plugs and then place the cylinder head with the combustion chambers facing up. Fill the chambers with solvent, and let the heads sit for a few minutes. If the seats leak, solvent will leak down the stem and into the ports. SERVICE TIP  The upper two grooves of the valve stem are for the retainer assembly; the third groove down the stem is for the O-ring seal. On some engines, umbrella seals can be used in place of O-ring seals.

Caution Positive-type valve stem seals require a protective sleeve be installed over the valve keeper grooves to prevent damage to the seal.

Special Tools Valve spring compressor

OHC Cylinder Head Assembly Following is a general procedure for assembling an OHC engine cylinder head with camshaft bearing caps. Follow the preceding procedure to install the valves; then return here to continue with the assembling process: 1. Assemble the rocker arm assembly following the manufacturer’s procedures (Figure 10-40). 2. Clean the camshaft and cylinder head bores. 3. Lubricate the bores and journals with engine oil or assembly lube. 4. Install the camshaft into the lower half of the bores. 5. Rotate the camshaft so the keyway is facing up at the 12:00 position. This is top dead center (TDC) for number 1. 6. Insert correct size plastigage strips on each journal. 7. Position the rocker arm assembly (or bearing caps) in place, and loosely install the bolts. Check the bolts before reusing them; the threads must be clean and undamaged.

Special Tools Plastigage Dial indicator If the cylinder head is an OHC design, perform the camshaft service before assembling the cylinder head.

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Chapter 10 Intake rocker arm #6 camshaft holder

#5 camshaft holder

#4 camshaft holder

#3 camshaft holder

#2 camshaft holder

#1 camshaft holder

Spring Exhaust rocker arm

Wave washer

Intake rocker shaft

Exhaust rocker shaft

Figure 10-40  Rocker arm assembly.

Caution Make sure the rocker arms are in the proper position on the valve stems. In addition, loosen and back off the valve adjustment screws before installing the rocker arm assembly. If these screws are not backed off, the valves may be forced against the pistons, resulting in valve damage.

8. Tighten each rocker arm two turns at a time following the recommended tightening sequence. 9. Finish torquing the rocker arm assembly bolts to the final torque value. 10. Remove the rocker arm assembly, and measure the plastigage at its widest point. This is the amount of oil clearance. Check the results against the specifications. 11. Remove the plastigage from the journals. 12. Slide the camshaft seal onto the camshaft. 13. Some manufacturers require liquid sealers to be used in specified locations. Use the specified sealer type. 14. Position the rocker arm assembly in place, and loosely install the bolts. 15. Tighten each rocker arm two turns at a time following the recommended tightening sequence. 16. Finish torquing the rocker arm assembly bolts to the final torque value. 17. Seat the camshaft by pushing it all the way to the rear of the cylinder head. 18. Install a dial indicator against the front of the camshaft, and zero the gauge (Figure 10-41). 19. Push the camshaft back and forth to measure the end play. Compare the results with specifications. 20. Remove the dial indicator. 21. Install back plates (if equipped) and the camshaft pulley. Torque all bolts to proper specifications.

Camshaft

Figure 10-41  Checking camshaft end play after reassembly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

For other styles of camshaft mounting, follow the manufacturer’s recommended torque values and sequences. Installing the camshaft and followers may require the use of special tools. Verify bearing oil clearances before considering the procedure completed. Coat all components with engine oil before installing them.

VALVE ADJUSTMENT Valve adjustment can be performed before the engine is installed after an overhaul or replacement. To perform a periodic adjustment, you will remove the valve cover(s) and follow the same procedures. The adjustment must be correct to provide long valve life and excellent engine performance. If there is too much clearance (lash) in the valvetrain, it will clatter and the valves won’t open as much as they should. Too little valve lash can cause valve burning and poor engine performance. Some hydraulic lifters are adjustable and are set after replacement or reinstallation. Other hydraulic lifters are not adjustable. Mechanical lifters require periodic adjustment. One method of adjustment involves loosening or tightening an adjustment screw on the rocker arm (Figure 10-42). Another process involves measuring the lash and adjusting the clearance by changing the size of a shim installed between the camshaft and the follower. We’ll look at the general methods of adjusting each type of valvetrain.

Adjustment Intervals Adjustable hydraulic lifters should be adjusted during installation of new or used lifters or whenever the valvetrain has been disassembled. An example would be after an onthe-car valve seal replacement. After reinstalling the rockers, the lifters must be adjusted. This initial adjustment should last as long as the valvetrain components or until they are disassembled again. If during normal service the valvetrain becomes noisy, check the lifter adjustment if no visible damage is seen before condemning the lifters. Mechanical or solid lifters require periodic adjustment. They should be adjusted at the specified interval. This may be as little as every 15,000 miles or as long as every 90,000 miles. Adjustment every 30,000 or 60,000 miles is a common recommendation. If the valves clatter, they should be adjusted regardless of the specified mileage.

Figure 10-42  These rocker arms have adjusting screws held in place with a locking nut. Use a feeler gauge to measure the clearance between the rocker arm and the valve tip. Adjust the screw to the correct clearance and tighten the locknut. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Symptoms of Improper Valve Adjustment When the valvetrain has too much lash, it cannot open the valve as far as it is designed to do. You can identify the problem by listening under the rocker cover for the telltale valvetrain clatter. It is a light, fast, tapping or ticking noise from under the valve cover(s). Loose valve adjustment will also affect engine performance. When the valves don’t open fully or for as long as they should, volumetric efficiency decreases. As you know, this will cause a loss of power, particularly at higher rpm. The lack of fresh air will also affect emissions as the engine may run too rich. If there is less than zero clearance, it means the valves are tight. They are held open more than they should be and may not close fully when on the camshaft’s base circle. This is a very dangerous situation; the valves can burn quickly. The valves need to fully seat to dissipate their heat. If the exhaust valves open too early in the combustion stroke, they are subject to too much heat. In severe cases, the engine will run poorly as the valves stay open too long, and overlap will be too great. The engine may backfire through the intake and exhaust. The engine might also turn over irregularly, as though the valve timing is off. It will also significantly increase hydrocarbon and carbon monoxide emissions.

Adjusting Hydraulic Lifters Some manufacturers use nonadjustable hydraulic lifters. In these cases, the proper “adjustment” method is to torque the rockers on their stands to the proper specification. If serious changes (valve and seat grinding) have been made that could affect the rocker geometry, pushrods or rocker stand shims of different length can be fitted. Follow the manufacturer’s procedures for determining when you must perform these “adjustments.” It is not common on modern passenger vehicle or light-duty truck engines to have to make any changes to the existing setup. The valves are smaller than they used to be, and you usually can’t take enough material off the valves to alter the valvetrain geometry significantly before the valve needs replacement. Commonly, hydraulic lifters are adjustable. The goal in adjusting hydraulic lifters is to center the plunger in the lifter bore (Figure 10-43). If the plunger is centered, it can adjust the valvetrain tighter or looser as needed without bottoming out at one end. Centering it gives the plunger equal travel in both directions. If it were adjusted too tight, the plunger would sit near the bottom of the bore and have little adjustment left as the valves wear. The procedure for adjusting hydraulic lifters is similar on most vehicles, but it is critical to look at the manufacturer’s service information to determine how much to tighten the rocker. When reassembling an engine after a rebuild, you should perform a preliminary adjustment during engine assembly and then make a final adjustment after the engine has run. You can perform the adjustment procedure while the engine is off or when it’s running. It’s messier with the engine running because oil is splashed around. Oil deflectors fit on top of the pushrod end of the rockers to help minimize the oil splash (Figure 10-44). In either case, you’ll need to remove the valve covers. To adjust the valves with the engine running: 1. Loosen a rocker bolt until you can hear the valve clatter; this raises the plunger toward the top of its bore. 2. Tighten the nut until the clatter goes away. Now the valve is at zero lash with the plunger still near to the top. 3. Tighten the rocker nut the number of turns specified by the manufacturer, typically a half to one-and-a-half turns. This centers the plunger in the bore. 4. Repeat for each valve. To adjust the valves with the engine off: 1. Rotate the engine to TDC number 1. One-half of the rockers should be loose with the cam on the base circle; these can be adjusted. You should retrieve this service Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Centered in bore

Plunger

Plunger bottomed in bore—rocker adjustment too tight

Figure 10-43  Follow the correct procedure to center the plunger in the bore. This will allow the lifter to adjust the valvetrain both looser and tighter.

Figure 10-44  These oil deflectors clip over the rocker arms and around the pushrod, blocking the oil splash hole on top of the rocker.

information and have it with you. For example, one engine may specify to adjust intake and exhaust number 1, intake on number 5, and exhaust on number 2. Then you rotate the crankshaft 360 degrees and adjust intake and exhaust number 6, intake on number 2, and exhaust on number 4 and number 5. As an alternate method, you can rotate the engine until you reach TDC number 1 compression and adjust those valves. Then rotate the engine, and watch the rockers for the next cylinder in the firing order to come up to TDC on compression. You will watch the intake rocker come up and then become loose as the piston approaches TDC on the compression stroke. This puts the camshaft on the base circle for all the valves in that cylinder. Adjust them, and continue to rotate the engine through the firing order, adjusting as you go. 2. To make the adjustment, tighten (if necessary) the rocker just until the lash is removed between the rocker arm and the valve and the pushrod does not spin freely or there is no lash between the rocker and the valve (Figure 10-45). 3. Tighten the rocker arm nut the specified number of turns. 4. Repeat for each valve.

Figure 10-45  Tighten the rocker nut on its stud until the pushrod resists turning. Rotate the nut the specified number of degrees further to achieve the proper adjustment. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Caution Do not use a generic specification when adjusting lifters. If you adjusted a rocker nut one-and-a-half turns when the specification was a half turn, you would significantly misadjust the lifter.

Caution When using a remote starter to turn the engine over, be sure the transmission is in neutral, the parking brake is set, and the ignition key is off.

When the valves are adjusted, replace the valve cover gasket and properly torque the cover. Wipe up all excess oil that may have spilled on the exhaust manifold or other components. Start the engine. Make sure that it cranks over and starts and runs normally. Listen for any valvetrain clatter. Readjust if necessary.

ADJUSTING MECHANICAL FOLLOWERS WITH SHIMS Engines that use mechanical followers with the camshaft riding above them may use shims to adjust the valves (Figure 10-46). To check the clearances, locate the clearance specifications in the service information. The clearances are also often listed in the engine information on the decal on the underside of the hood. The specifications will be given for when the engine is either hot or cold. An example could be 0.008- to 0.012-inch intake, 0.016- to 0.020-inch exhaust when hot. Be sure to adjust the valves with the engine properly heated or cooled. First you will check the clearance, and then you will tighten or loosen the clearance by fitting a thicker or thinner shim, respectively. On some engines, you can remove the shim by depressing the follower and using a magnet or special tool to pull the shim out. Several different tools are available for this job, depending on the vehicle (Figure 10-47). On other engines, you may have to remove the camshaft to access the shims; they may be placed under the follower. On engines with removable shims, you can adjust one valve at a time. When you have to remove the cam to replace shims, you’ll need to carefully record all your clearances first. Then you can remove the cam and bring all the clearances within specification. On either type, always double-check your adjustment after the new shim is installed. To begin adjustment, rotate the engine, using the crank bolt, to TDC number 1. You will be able to check half of the valves. Run a feeler gauge under the camshaft on top of the follower. When you fit a gauge that has a little drag as you pass it under the cam, you have found the clearance (Figure 10-48). Record the clearance. You can see which clearances can be checked by looking for the ones where the base circle of the camshaft is on the follower. Rotate the engine another 360 degrees, and you can check the remaining valves. You can look for the specified valve sequence in the service information if you have any difficulty determining which valve should be adjusted. Other technicians will use a remote starter and “bump” the engine over until each cylinder in turn is at TDC or until each camshaft lobe is facing straight up. To adjust the clearance, you’ll change the thickness of the shim. Use a micrometer to measure the thickness of the current shim. Calculate the needed change in

Cam lobe

Tappet Adjustable shim

Figure 10-46  On this engine the shim sits on top of the tappet or follower.

Figure 10-47  This tool can be used on some engines to depress the follower so a magnet can be used to extract the shim.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 10-48  Carefully check the clearance between the shim and the camshaft while the camshaft is on its base circle.

clearance for the valve, and select a shim that is much thicker or thinner. Let’s look at an example: 1. Cylinder number l exhaust clearance is 0.009 inch. The specification is 0.016 to 0.020 inch. 2. The valve clearance should be 0.007 to 0.011 inch greater. 3. The existing shim size is 0.156 inch. 4. The clearance needs to be 0.007 to 0.011 inch greater, so the shim must be that much thinner. 5. Select a shim: 0.156 to 0.010 inch 5 0.146 inch. 6. Install the new shim, and recheck the clearance. After you have adjusted and checked each of the valves, crank the engine over for a few seconds and recheck the clearances. You need to be sure that all the shims are properly seated in the followers. Readjust as needed. SERVICE TIP  When adjusting mechanical drivetrains make sure the clearance specifications are for “cold” if adjusting cold.

ADJUSTING VALVE CLEARANCE USING ADJUSTABLE ROCKER ARMS Another common method of adjusting mechanical valvetrains is through the rocker arm. One side of the rocker may ride on the camshaft or a solid lifter. The other side can work on the valve. One end of the rocker arm has a locknut and adjusting screw. To adjust the valve, you can loosen the locking nut and turn the screw in or out to tighten or loosen the valve adjustment respectively (Figure 10-49). The clearance specifications will be similar to those with shim-adjusted valve lash. To adjust the valves: 1. Obtain the lash specifications, and be sure the engine is at the desired temperature. 2. Rotate the engine to TDC number 1, and note which valves can be adjusted using the service information. 3. Using feeler gauges, determine the clearance on the valve you are adjusting. The feeler gauge should fit in the clearance under the adjustment screw with light drag (Figure 10-50).

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Chapter 10 Screwdriver

Adjusting screw

Locknut

Rocker arm Feeler gauge

Figure 10-49  Loosen the locknut on the adjusting screw, fit the appropriate feeler gauge between the screw and the valve tip, and adjust the screw until some drag is felt on the feeler gauge.

Special Tools Torque wrench Alignment dowels

Figure 10-50  Check the clearance first to make sure that adjustment is needed.

4. If the valve needs adjustment, loosen the locknut just enough that you can turn the screw. Insert the desired thickness (clearance) feeler gauge under the lash adjuster, and lightly tighten the adjuster screw while alternately feeling the clearance. When there is just the right amount of drag, tighten the locknut (Figure 10-51). 5. Recheck your adjustment. This is essential as the adjustment can change as the locknut pulls the adjuster screw up. It may be necessary to adjust the valve a little snugly and then have it loosen up as you tighten the locknut. It is essential to recheck the adjustment after tightening the locknut. 6. Repeat for all the other valves adjustable at TDC number 1. Rotate the crank 360 degrees, and complete the adjustment of the valves. 7. Properly install the valve cover, and start the engine. It should turn over smoothly. 8. Allow the engine to warm up, and listen for any excessive valvetrain clatter and feel for rough running. Refer to Photo Sequence 22 for an additional method of adjusting valves with the engine installed. SERVICE TIP  If locating dowels are not used, alignment pins can be made to assist in head installation. Thread a couple of locating pins in the corners of the deck surface. Slide the cylinder head gasket over the pins, and locate it on the deck surface. Next, slide the cylinder head over the pins and onto the gasket. Install the head bolts finger-tight; then remove the alignment pins and install the correct bolts.

Installing the Cylinder Head If the engine is an OHC type, the cylinder heads must be installed before the timing components. On OHV engines, the timing components can be installed before the heads. The procedures for cylinder head installation are similar. On some OHC engines, the camshaft and valvetrain components can be installed into the head before the head is placed onto the engine block. Use the following checklist along with the appropriate service manual as the cylinder heads are installed. 1. Any bolts that enter into coolant or oil passages must have approved sealer applied to the threads. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Cylinder head gasket

8–9 mm

Dowel

Cylinder block

Figure 10-51  Three hands to hold the wrench, the screwdriver, and the feeler gauges would make this job easier.

Figure 10-52  Alignment dowel installation.

2. Be sure that the block and cylinder head surfaces are perfectly clean. As described earlier, the head bolt holes must also be cleaned. 3. Install any dowels that were originally equipped on the deck (Figure 10-52). PHOTO SEQUENCE 22

Typical Procedure for Adjusting Valves

P22-1  Prepare the vehicle and assess the task.

P22-4  Remove the necessary wiring and ­linkage to remove the valve cover.

P22-2  Read through and follow the service information procedures.

P22-5  Remove the valve cover following any sequence specified.

P22-3  This service information provides a diagram of how to line up the camshaft to adjust the valves.

P22-6  Remove the upper timing belt cover to access the timing marks on the camshaft sprocket.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 22 (CONTINUED)

P22-7  With the valve cover and timing cover off you have plenty of room to work.

P22-8  Rotate the engine through the access port in the wheel well to rotate the engine to line up the marks on the camshaft. Do not rotate the engine over with the camshaft sprocket bolt.

P22-9  Check the adjustment of the valves using feeler gauges and compare to specifications.

P22-10  Loosen the locknut and turn the adjusting screw to achieve the proper adjustment. Double-check your work after you retighten the locknut.

P22-11  Properly torque the new valve cover gasket and valve cover into place.

P22-12  Be sure to reinstall all hoses, connectors, and linkages you disconnected to remove the valve cover.

P22-13  Make sure your work is clean and that the engine runs smoothly and quietly before you call the job complete.

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4. Locate any markings on the cylinder head gasket that identify the proper direction for installation (Figure 10-53). 5. Position the new head gasket over the dowels, and check for proper fit. 6. Locate the crankshaft a few degrees before TDC so all pistons are below deck height. 7. Position the cylinder head over the dowels. On V-type engines, make sure the correct head is installed onto the correct bank. 8. Install and torque the cylinder head bolts. Most manufacturers specify multiple steps to torquing the head bolts. Follow these instructions to prevent ­warpage (Figure 10-54). Also follow the correct torque sequence. Torque-to-yield ­cylinder head bolts are used in many engines. These bolts must be tightened to the specified torque and then rotated a specific number of degrees (Figure 10-55). ­Torque-to-yield bolts must be replaced each time the cylinder head is removed and replaced.

Cylinder head

Head gasket Engine block

Figure 10-53  Most cylinder head gaskets have markings to indicate proper installation direction.

10

4

2

6

8

7

5

1

3

9

Front

Figure 10-54  Typical cylinder head torque sequence.

Figure 10-55  A torque angle gauge allows you to accurately measure the degrees of turning.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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ON-CAR SERVICE You can replace worn valve seals or springs without removing the cylinder head from the engine. Worn valve seals will cause oil consumption. Valve seals often wear as a result of worn valve guides (Figure 10-56). The customer will likely notice a big cloud of blue smoke just after starting the vehicle. The oil on the top of the head leaks down past the valve seals as the vehicle sits; when it starts, the oil in the combustion chamber burns. Blue smoke is also often seen after a period of idling or deceleration. High engine vacuum pulls oil past the weak intake valve seals into the combustion chamber. The resulting blue smoke is a telltale sign of worn seals. This pattern of smoking is different than oil consumption caused by worn rings. Ring troubles generally lead to more consistent smoking that is worse when the engine is under a load. Before replacing the valve seals, it is a good idea to check for valve guide wear. Often the seals are damaged because the guides are allowing the valves to wobble back and forth in the seals. Check the engine vacuum at idle and at 2,500 rpm. If the vacuum fluctuates at idle but smoothes out at higher rpm, suspect worn valve guides. The valve is not being guided correctly onto its seat at lower rpms. You can also check running compression. The compression would be lower at idle when the valve has more time to rock back and forth in the guide. Running compression would return to a nearly normal value at 2,500 rpm. To replace a valve seal with the head installed, you must work one cylinder at a time (see Photo Sequence 23). Remove the valve cover(s) first. The critical issue during this service is to prevent the valve from dropping into the engine when the keepers are removed. That mistake could require that you remove the cylinder head. Place the first cylinder at TDC on the compression stroke. Remove the camshaft, rocker arm, and lifter or follower as needed to gain access to the valve retainer. Use a cylinder leakage tester or regulated shop air to apply 100 psi of air pressure into the cylinder with the valves closed. This will keep the valves up in the head while you release the valve retainer and keepers. Place a socket over the valve retainer, and give it a light rap to break any varnish loose; this may make it much easier to compress the spring. Use a valve spring compressor to compress the spring and remove the keepers (Figure 10-57). Set the spring, retainer, and keepers safely aside. Note which end of the spring faces up; often tighter coils are placed at the bottom toward the head. Use a screwdriver or seal puller to remove the old valve seal. Check for damage or excessive scoring on the valve stem that could ruin a new valve seal. Lubricate the inner lip of the new valve seal with oil, and install it onto the valve. Many positive lock seals must be driven down onto the

Engine oil

Engine oil

A

B

Figure 10-56  Worn valve seals allow oil to be pulled into the combustion chamber through the guides. It burns and exits the exhaust port and tailpipe as blue smoke. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Shop air

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Spring compressed

Figure 10-57  Compressed air holds the valve up while you compress the spring to remove the keepers.

PHOTO SEQUENCE 23

Replacing Valve Seals on the Vehicle

P23-1  Remove all necessary wiring and vacuum lines from the intake ducting.

P23-2  Remove the intake ducting to access the valve cover.

P23-3  Move wiring and remove the bolts as needed to remove the valve cover.

P23-4  Remove the valve cover.

P23-5  Rotate the engine to TDC firing on the cylinder you are going to work on first. You can watch the intake valve close and go a bit further until the piston is at TDC.

P23-6  Apply 100 psi of air pressure to the cylinder to hold the valves up.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

PHOTO SEQUENCE 23 (CONTINUED)

P23-7  Remove the rocker arms and compress the valve spring. Remove the keepers and the spring assembly. Set it aside for reinstallation.

P23-10  Replace the valve spring and keepers. Give a light rap on the valve retainer to be sure the keepers are fully seated.

P23-8  Pry the old seal off or use a valve seal removing tool if available.

P23-11  Adjust the rocker arm by removing the lash and turning the adjusting bolt one turn further. Check the specifications, this will vary with different vehicles.

P23-9  It is best to use a valve seal installation tool made for the job, but if you are careful you can find just the right size deep socket to drive the new seal on without damaging the seal or popping the valve open.

P23-12  Be sure to torque the valve cover properly to prevent a comeback.

P23-13  Fully reassemble the engine and be sure it runs quietly, smoothly, and without leaks. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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head to seat properly. Use a valve seal installation tool to fit the seal into its proper position. If the correct tool is not available, you can use a deep socket that matches the diameter of the seal but will easily slide over the valve stem. Be sure the socket is deep enough to tap the seal down without hitting the valve tip. Knocking the tip could release the air pressure in the cylinder and cause you to drop a valve into the cylinder, necessitating head removal. Refit the valve spring, retainer, and keepers. When the valve is back in place, take the socket and lightly rap again on the retainer to check that the keepers are fully seated. Repeat the procedure for the other valve(s) on this cylinder. Then move to the next cylinder and repeat the process to replace the whole set of valve seals.

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Caution Do not rotate the camshaft or crankshaft without the timing belt properly installed unless instructed to do so in the service manual.

VALVE SPRING REPLACEMENT Weak or broken valve springs can cause valve float and valve burning. When the valve hangs open like this, you can notice misfiring and power loss at higher rpms. If the valve spring is broken, the valve may never close. This can cause a steady misfire and popping out of the intake if it is an intake valve spring and out of the exhaust if it is a broken exhaust valve spring. A broken valve spring must be replaced immediately to prevent the valve from burning. The procedure to replace valve springs is the same as for replacing valve seals. As a matter of fact, technicians should replace the valve seals while they have the valves disassembled. Once the valve spring is removed, carefully inspect it for cracks, proper free length, squareness, and opening tension. To ensure a quality repair, test the valve spring before replacing it to verify it has failed. CUSTOMER CARE  Always concentrate on thorough and quality work to achieve customer satisfaction. Most customers do not mind paying for vehicle repairs if they believe that the work is necessary and performed properly. This is evidenced in the following case study. A follow-up phone call to ensure that the customer is satisfied a few days after the service work demonstrates that you consider quality work and customer satisfaction a priority.

CASE STUDY A customer came in very upset about his vehicle. He said the engine was blowing blue smoke out the tailpipe, but he didn’t have enough money to rebuild the engine. The technician drove the vehicle and noticed that the engine did not smoke during acceleration as it would if the rings were worn. Instead, he noticed smoking after a period of idle. To confirm his suspicion that the rings were in reasonable condition, he performed a cylinder leak-down test. The results showed less than 15 percent leakage on all four cylinders. He also performed a vacuum test to be sure that the valve guides didn’t indicate excessive wear. The technician went back to the customer and reported his findings. He asked the customer if he had noticed that it smoked heavily during the first start-up of the day. When the customer told him that was indeed the case, the technician let him know that his symptom was common for worn valve system seals, which only cost a fraction of a full engine rebuild or replacement. The diagnosis and repair resulted in a very happy customer.

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Chapter 10

ASE-STYLE REVIEW QUESTIONS 1. Technician A says that cylinder head and block deck resurfacing may affect rocker arm geometry. Technician B says that intake manifold replacement will change rocker arm geometry. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that if face wear on the lifter runs across the face, it indicates that the lifter was stuck in its bore. Technician B says that a worn lifter can cause ­valvetrain clatter. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. Technician A says that installing a modified camshaft may affect rocker geometry. Technician B says that using different pushrods can correct rocker geometry. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 4. Technician A says to check the pushrod for warpage and tip wear. Technician B says that wear on the side indicates that the pushrod guide is defective. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that a worn camshaft lobe can cause reduced engine power. Technician B says that a bent camshaft should be straightened. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

6. Technician A says that if you replace the ­camshaft, you should replace the lifters. Technician B says that lifters should be slightly concave on their face. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. Technician A says to measure valve installed height when reassembling the cylinder head. Technician B says to shim the valve springs if the valve installed height is below specifications. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Valve spring free length should be measured: A. with the valve and spring installed. B. with a machinist’s rule. C. with the valve in its fully opened position. D. with the spring on the bench. 9. A shim-type valvetrain is being adjusted. The exhaust clearance is specified at 0.016 in. to 0.020 in. (0.41 mm to 0.51 mm). The existing clearance is 0.027 in. (0.69 mm). The current shim is 0.116 (3.15 mm). To correct the clearance, install a shim _______________ thick. A. 0.146 inch (3.7 mm) B. 0.142 inch (3.6 mm) C. 0.130 inch (3.3 mm) D. 0.126 inch (3.2 mm) 10. Technician A says that you should replace the valve seals when replacing the valve springs. Technician B says that you should check the ­condition of the valve guides before replacing the valve seals on the car. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

477

ASE CHALLENGE QUESTIONS 1. Technician A says that on a RWD vehicle with an OHV engine, the radiator usually needs to be removed to replace the camshaft. Technician B says that you can crack an overhead camshaft if you do not follow a bolt-loosening sequence. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that rocker arms should be replaced in their original positions if the camshaft will be reused. Technician B says that you typically resurface a rocker arm by about 0.002 to 0.004 inch to restore a good mating finish with the camshaft. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

4. Technician A says that lobe lift is determined by subtracting the base circle diameter from the distance from the bottom of the base circle to the end of duration. Technician B says that worn camshaft lobes may cause a heavy clicking noise at 1,500 rpm to 2,000 rpm. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that lifters are typically replaced during an engine overhaul. Technician B says that too little valve clearance can cause valvetrain clatter. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says on some engines valve stem seals can be replaced without removing the head. Technician B says rocker arms can affect valve lift. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

479

JOB SHEET

62

VALVE STEM SEAL REPLACEMENT ON AN ASSEMBLED ENGINE Upon completion of this job sheet, you should be able to replace the valve stem seals while the engine is still in the vehicle or on an assembled engine. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: B.8. Replace valve stem seals on an assembled engine; inspect valve spring retainers, locks/keepers, and valve lock/keeper grooves; determine necessary action. Tools and Materials • Cylinder compression tester kit or cylinder leakage tester kit • Technician’s tool set • In-vehicle valve spring compressor Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

1. Rotate the engine to TDC of the compression stroke (similar steps for testing cylinder leakage).

h

2. Remove the spark plug, and insert the testing extension from the cylinder leakage tester into the hole. The test extension must have the Schrader valve removed.

h

3. Connect the testing extension to an air source, and pressurize the cylinder to 80–100 psi. This will hold the valves in place when you remove the springs and retainers/ locks.

h

4. Remove any components, such as the valve cover and others, to gain access to the valve springs and retainers/locks.

h

5. Using the special spring compressor, connect it to the cylinder head and compress one of the valve springs. Once the spring is compressed, remove the retainer/locks/ keepers/etc.

h

6. With the spring removed, remove the valve stem seal.

h

7. Insert a new valve stem seal.

h

8. Inspect the valve spring, retainers, locks, keepers, and keep groove before reinstalling them. Describe what you found. _________________________________________________________________________ _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Task Completed 9. Reassemble the valve spring, reduce the air pressure to zero, and move to the next cylinder.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

481

JOB SHEET

63

VALVE SPRING INSPECTION Upon completion of this job sheet, you should be able to properly reassemble the cylinder head. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: B.10.

Inspect valves and seats.

Tools and Materials • Valve spring height measuring equipment • Valve spring compressor and scale • Dial caliper Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Describe the type of valvetrain in the engine: ______________________________________________________________________________ Procedure

Task Completed

Use the valve springs that you removed from the engine. Write down the information, and then perform the following tasks: 1. What is the specification for the spring free length (sometimes called free height)? Intake ______________________________ Exhaust ______________________________ 2. Using the dial calipers, measure the free length (free height) of each spring: Intake ______/______ Exhaust ______/______ Number 1 Number 2 Intake ______/______ Exhaust ______/______ Number 3 Intake ______/______ Exhaust ______/______ Number 4 Intake ______/______ Exhaust ______/______ Intake ______/______ Exhaust ______/______ Number 5 Number 6 Intake ______/______ Exhaust ______/______ Number 7 Intake ______/______ Exhaust ______/______ Number 8 Intake ______/______ Exhaust ______/______ Place an * in the preceding chart for any springs that are out-of-specifications. 3. Inspect each spring for cracks and signs of rotation and wear. Describe what you found. _________________________________________________________________________ _________________________________________________________________________ 4. Place each spring in the spring compressor scale, and measure the force at the specified height. Record your findings. Number 1 Intake ______/______ Exhaust ______/______ Number 2 Intake ______/______ Exhaust ______/______ Number 3 Intake ______/______ Exhaust ______/______ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 10

Task Completed Number 4 Number 5 Number 6 Number 7 Number 8

Intake ______/______ Intake ______/______ Intake ______/______ Intake ______/______ Intake ______/______

Exhaust ______/______ Exhaust ______/______ Exhaust ______/______ Exhaust ______/______ Exhaust ______/______

5. Put an * in the preceding chart for any springs that are out-of-specifications.

h

6. Based on your tests and results, what are your recommendations?

_________________________________________________________________________

_________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

483

JOB SHEET

64

INSPECTING THE CAMSHAFT Upon completion of this job sheet, you should be able to properly inspect the camshaft for wear and damage. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.5. Inspect and replace camshaft and drive belt/chain; includes checking drive gear wear and backlash, end play, sprocket and chain wear, overhead cam drive sprocket(s), drive belt(s), belt tension, tensioners, camshaft reluctor ring/tone wheel, and valve timing components; verify correct camshaft timing. Tools and Materials • Service manual • Micrometer • Dial indicator • Camshaft

Task Completed

Procedure Using the camshaft from the engine that you have disassembled and the proper service manual, you will identify and perform the required steps to inspect the camshaft. 1. What page of the service manual covers the procedure for inspecting the camshaft? 2. Perform a visual inspection of the camshaft, and record your results.

Intake Lobes

Exhaust Lobes

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

3. Describe the wear pattern on the lobes. 4. Put an * in the previous chart for any lobes that show abnormal wear. 5. What are the lobe lift specifications? Intake lobes _______________ Exhaust lobes _______________ 6. Measure the lift for each lobe, and record your results.

Intake Lobes

Exhaust Lobes

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

484

Chapter 10

Task Completed Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

7. Put an * in the previous chart for any lobes that are out-of-specification.

h

8. List the journal measurements: Size Taper Out-of-Round Journal 1

_______________

_______________

_______________

Journal 2

_______________

_______________

_______________

Journal 3

_______________

_______________

_______________

Journal 4

_______________

_______________

_______________

Journal 5

_______________

_______________

_______________

9. Put an * in the previous chart to note any journals that are out-of-specification. 10. Measure each lobe for base circle runout, and record your results.

Intake Lobes

Exhaust Lobes

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

11. Put an * in the previous chart for any lobes that are out-of-specification.

h

12. Based on your evaluation of the camshaft, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

485

JOB SHEET

65

INSPECTING THE LIFTERS (LASH ADJUSTERS) Upon completion of this job sheet, you should be able to properly inspect the lifters for wear and damage. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: B.12.

Inspect valve lifters; determine necessary action.

Tools and Materials • Service manual • Leak-down tester • Valve lifters Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Using the lifters removed from the engine that you have disassembled and the proper ­service manual, you will identify and perform the required steps to inspect the lifters. 1. What page of the service manual covers the procedure for inspecting the lifters? _________________________________________________________________________ 2. Perform a visual inspection of each lifter, and record your results.

Intake Lifters

Exhaust Lifters

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

3. Put an * in the previous chart for any lifters that show abnormal wear or damage.

h

4. What is the specification for lifter leak-down testing? _________________________________________________________________________ _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

486

Chapter 10

Task Completed 5. Perform a leak-down test of each lifter, and record the time.

Intake Lifters

Exhaust Lifters

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

6. Put an * in the previous chart for any lifters that are out-of-specification.

h

7. Based on your test results, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

487

JOB SHEET

66

INSPECTING THE PUSHRODS AND ROCKER ARMS Upon completion of this job sheet, you should be able to properly inspect the pushrods for wear and damage. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.3. Inspect pushrods, rocker arms, rocker arm pivots and shafts for wear bending, cracks, looseness, and blocked oil passages (orifices); determine necessary action. Tools and Materials • Service manual • Pushrods Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Using the pushrods removed from the engine that you have disassembled and the proper service Task Completed manual, you will identify and perform the required steps to inspect the pushrods. 1. What page of the service manual covers the procedure for inspecting the pushrods? 2. Perform a visual inspection of each pushrod, and record your results.

Intake Pushrods

Exhaust Pushrods

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

3. Put an * in the previous chart for any lifters that show abnormal wear or damage.

h

4. Inspect each pushrod for warpage, and record your results.

Intake Pushrods

Exhaust Pushrods

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

488

Chapter 10

Task Completed Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

5. Put an * in the previous chart for any pushrods that are bent.

h

6. Clean the oil passage through each pushrod.

h

7. Inspect the oil passages for oval shape or edge chamfering.

h

8. Inspect the rocker arms for damage, cracks, and excessive wear, and record your results.

h



Intake Rockers

Exhaust Rockers

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

9. Check the rocker arm shafts, pivots, and mounting hardware for wear, bends, and cracks. What did you find? _________________________________________________________________________ 10. Based on your test results, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

489

JOB SHEET

67

CHECKING AND ADJUSTING VALVE CLEARANCE Upon completion of this job sheet, you should be able to properly check and adjust the valve clearance. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B4.

Adjust valves (mechanical or hydraulic lifters).

This job sheet addresses the following MLR task for Engine Repair: B1.

Adjust valves (mechanical or hydraulic lifters).

Tools and Materials • Service manual • Engine with adjustable valvetrain • Feeler gauge set • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Using a provided engine and the proper service manual, you will identify and perform the required steps to check and adjust the valve clearance. 1. What page of the service manual covers the procedure for adjusting the valve clearance? 2. What is the specification for valve clearance? Intake valves _______________ Exhaust valves _______________ 3. Is the specification for:

h HOT h COLD

4. What valves are adjusted with the engine at TDC number 1 compression stroke? _________________________________________________________________________ _________________________________________________________________________ 5. What location must the crankshaft be in to adjust the remaining valves? _________________________________________________________________________ 6. What method is used to adjust the valve clearance? h ADJUSTING NUT h SHIMS h SCREW h PUSHROD LENGTH 7. With the engine at TDC number 1 compression stroke, measure the valve clearance, and record your results.

Intake Valves

Exhaust Valves

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

490

Chapter 10

Task Completed Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

8. Put an * in the previous chart for any valve clearances that are out-of-specification.

h

9. Correct any valves that are out-of-specification.

h

10. Rotate the crankshaft to the position determined in step 5.

h

11. Measure the clearance of the remaining valves, and record your results.

Intake Valves

Exhaust Valves

Cylinder 1

_______________

_______________

Cylinder 2

_______________

_______________

Cylinder 3

_______________

_______________

Cylinder 4

_______________

_______________

Cylinder 5

_______________

_______________

Cylinder 6

_______________

_______________

Cylinder 7

_______________

_______________

Cylinder 8

_______________

_______________

12. Put an * in the previous chart for any valve clearances that are out-of-specification.

h

13. Correct any valves that are out-of-specification.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

Name ______________________________________

Date __________________

491

JOB SHEET

68

REASSEMBLING THE CYLINDER HEAD Upon completion of this job sheet, you should be able to properly reassemble the cylinder head. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.1. Remove cylinder head; inspect gasket condition; install cylinder head and gasket; tighten according to manufacturer’s specifications and procedures. Tools and Materials • Torque wrench • Valve spring height measuring equipment • Valve stem height measuring equipment • Valve spring compressor Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Describe the type of valvetrain in the engine: ______________________________________________________________________________ Procedure

Task Completed

Using the cylinder head(s) that you removed from the engine and the proper service ­manual, you will identify and perform the required steps to reassemble the cylinder head(s): 1. Replace any studs that were removed.

h

2. Clean all oil and coolant passages.

h

3. Install oil and coolant passage core plugs and cups.

h

4. Polish the valve stems with a fine crocus cloth and solvent. Make sure all valves are clean.

h

5. Lubricate the valve stem, and install the valve into the cylinder head. Check spring height and record your results. Number 1

Intake _______________ Exhaust _______________

Number 2

Intake _______________ Exhaust _______________

Number 3

Intake _______________ Exhaust _______________

Number 4

Intake _______________ Exhaust _______________

Number 5

Intake _______________ Exhaust _______________

Number 6

Intake _______________ Exhaust _______________

Number 7

Intake _______________ Exhaust _______________

Number 8

Intake _______________ Exhaust _______________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

492

Chapter 10

Task Completed 6. What is the specification for the spring height? Intake _______________ Exhaust _______________ 7. Place an * in the preceding chart for any valves that are out-of-specifications. 8. Indicate below what size shim will be required to correct installed spring height: Number 1

Intake _______________ Exhaust _______________

Number 2

Intake _______________ Exhaust _______________

Number 3

Intake _______________ Exhaust _______________

Number 4

Intake _______________ Exhaust _______________

Number 5

Intake _______________ Exhaust _______________

Number 6

Intake _______________ Exhaust _______________

Number 7

Intake _______________ Exhaust _______________

Number 8

Intake _______________ Exhaust _______________

9. Install the valve stem seals. To install most positive lock seals, the valve will need to be removed before the seal is installed. Some seals are installed after the springs are installed. What type of seals are used? _______________ If different size seals are used for the intake and exhaust valves: What color are the intake valve seals? _______________ What color are the exhaust valve seals? _______________ 10. Install the valves (one at a time) into the cylinder head.

h

11. Install the correct size spring shim as determined above.

h

12. Depending on seal type, install the stem seal.

h

13. Place the valve spring over the stem. Is the valve spring directional? If yes, Yes h  No h which direction does it face? _________________________________________________________________________ 14. Locate the retainer over the valve spring.

h

15. Use an approved spring compressor to compress the spring just far enough to install the keepers. If O-ring seals are used, install them now.

h

16. Install the keepers, making sure they are locked in place.

h

17. Slowly release the valve spring compressor and remove it.

h

18. Use a soft-faced hammer, and tap the top of the valve stem to ensure the keepers are properly installed.

h

19. Attempt to rotate the valve spring by hand. Note any that rotates. Number 1

Intake _______________ Exhaust _______________

Number 2

Intake _______________ Exhaust _______________

Number 3

Intake _______________ Exhaust _______________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Valvetrain Service

493

Task Completed Number 4

Intake _______________ Exhaust _______________

Number 5

Intake _______________ Exhaust _______________

Number 6

Intake _______________ Exhaust _______________

Number 7

Intake _______________ Exhaust _______________

Number 8

Intake _______________ Exhaust _______________

20. If the valve spring rotates, what must be done?

h

21. Repeat for all valves.

h

22. Lubricate the stem tips with a multipurpose grease.

h

23. On OHV cylinder heads, install the rocker arms, fulcrums, or shafts. Do not tighten the rocker arm bolts at this time.

h

24. Turn the cylinder head over, and test for leakage. Indicate your results. Number 1

Intake _______________ Exhaust _______________

Number 2

Intake _______________ Exhaust _______________

Number 3

Intake _______________ Exhaust _______________

Number 4

Intake _______________ Exhaust _______________

Number 5

Intake _______________ Exhaust _______________

Number 6

Intake _______________ Exhaust _______________

Number 7

Intake _______________ Exhaust _______________

Number 8

Intake _______________ Exhaust _______________

25. If leakage is detected, consult your instructor. If you are working on an OHC engine, complete the following steps: 26. Using the service manual procedures, assemble the rocker arm assembly.

h

27. Clean the camshaft and the camshaft bores.

h

28. Lubricate the camshaft bores with engine oil or assembly lube.

h

29. Install the camshaft into the cylinder head.

h

30. Rotate the camshaft so it is in position for TDC number 1 cylinder. How is this identified? _________________________________________________________________________

h

31. If the camshaft uses journal caps, place a piece of plastigage on each camshaft journal.

h

32. Make sure that the cylinder head is lifted so the valves can open if needed.

h

33. If all one assembly, install the rocker arm shaft and caps (or the journal caps if separate assemblies).

h

34. Following the service manual procedure, torque the cap bolts (or arm assembly) to specifications. Specified torque: _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Task Completed 35. Remove the caps by reversing the torque sequence, and measure the plastigage. Bore 1 _______________ Bore 2 _______________ Bore 3 _______________ Bore 4 _______________ 36. Compare measurements to clearance specifications. Specifications: _________________________________________________________________________ 37. Place an * in the previous chart to identify any bores that are out-of-specification. If any are out-of-specification, consult your instructor and determine needed repairs. 38. Remove the plastigage, and install the camshaft seal.

h

39. Reassemble the caps (rocker arm assembly), and tighten in proper sequence and to proper torque.

h

40. Measure camshaft end play. Actual _______________ Specifications _______________ If not within specifications, consult your instructor and determine needed repairs. 41. Install back plates (if used) and the camshaft timing sprocket. Is the sprocket directional?

h Yes h No

If yes, how is the direction determined? _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 11

TIMING MECHANISM SERVICE

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■ ■■ ■■ ■■

■■

The symptoms of a jumped or broken timing mechanism. How to perform a chain/belt deflection test and interpret the results. How to inspect the timing belt or chain tensioner.

■■

How to inspect the sprockets, idler pulleys, and guides. How to discuss the possible extent of damage on an interference engine with the customer before beginning the job or offering an estimate. How to replace and properly time the timing mechanism of an OHC engine using a timing belt.

■■

■■

■■

How to replace and properly time the timing mechanism of an OHV engine using a timing chain. How to replace and properly time the timing mechanism of an OHC engine using a timing chain. How to replace and properly time the timing mechanism of an engine with variable valve timing. How to inspect an Active Fuel Management or Variable Cylinder Displacement System for Proper Operation.

Terms To Know Backlash

Camshaft position actuator

INTRODUCTION To prepare for valve timing mechanism service, you must carefully inspect the components and decide which need replacement. Even when the timing mechanism is being replaced during a major engine overhaul, you should carefully inspect for damage of components to determine if there was a particular cause for the wear. Belts, chains, and gears must be inspected for wear. Tensioners, sprockets, and guides must also be thoroughly evaluated to make a good decision about which components should be replaced. You want to provide repairs in a cost-effective manner but without the risk of premature failure of your work. In many cases, you will replace multiple components in the timing mechanism. You should use the manufacturer’s specific procedures when that information is available or if you have any doubt about your diagnosis. There are also industry standard procedures for determining the condition of belts, chains, and gears, which we discuss here. These inspections will serve well to give you an overview of the inspection process. SERVICE TIP  “Crrraaaaaaaaank, crank, crank, crrraaaaaaaaank, crank, crank, pop, pop.” That’s an engine cranking over at irregular speeds and backfiring; it’s a telltale sign of a valve timing mechanism that has jumped out of time. If the engine is old enough to have adjustable ignition timing, check that out, too; it can cause the same symptoms. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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WARNING  It is important to know whether the engine with a suspected timing mechanism problem is an interference or free-wheeling type. If it is an interference engine, major damage to the engine may already have occurred. You could also incur damage if you rotate the engine to test compression or rotate the engine by hand when the valves are hitting the top of the pistons. Check the service information for the vehicle you are working on to be sure you provide professional service for your customers.

SYMPTOMS OF A WORN TIMING MECHANISM We mentioned that a worn timing chain may slap against the cover or against itself on a quick deceleration and make a rattling noise. Use a stethoscope in the area of the chain to confirm your preliminary diagnosis, and then proceed with the checks described in the next section to confirm the extent of the damage (Figure 11-1). A customer may also report that the engine seems to have poor acceleration from starts but runs well, perhaps even better, at higher rpms. When there is slack in the chain, the camshaft timing is behind the crank. This is called retarded valve timing. This improves high-end performance while sacrificing low-end responsiveness. Backlash is the small amount of clearance between the gear teeth that allows room for expansion as the gears heat up.

SERVICE TIP  A noisy timing chain that is slapping against the timing cover should be replaced right away to avoid failure and the need for more costly repairs. Backlash is the small amount of clearance between the gear teeth that allows room for expansion as the gears heat up.

Figure 11-1  Listen for a slapping or rattling noise on deceleration. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Timing gears or cam phasers may clatter on acceleration and deceleration. The engine does not have to be under a load; just snap the throttle open and closed while listening under the cover for gear clatter. The customer is unlikely to notice the reduced low-end performance before the gears break from too much backlash. Customers with worn or cracked timing belts will notice nothing until their engines stop running or begin running very poorly. What you and they should be paying close attention to is the mileage on the engine and the recommended belt service interval. Skipping a recommended replacement is at the very least an invitation to meet a tow truck driver.

SYMPTOMS OF A JUMPED OR BROKEN TIMING MECHANISM When a timing chain, belt, or gear breaks and no longer drives the camshaft(s), you can often tell by the sound of how the engine turns over. It cranks over very quickly, and no sounds even resembling firing occur (Figure 11-2). The engine has no compression. Hopefully, it has been towed to your shop; that is the only way it will run again. When a timing chain, belt, or gear skips one or more teeth (jumps time), it sets the valve timing off significantly. Some engines will run when the timing is off one or even two teeth, but not well. Usually you can hear the problem as the engine cranks over. It turns over unevenly; the engine speeds up and then slows down as you crank. Idle quality, acceleration, and emissions will be affected. If the timing is off significantly, it will pop out of the intake or exhaust or backfire under acceleration. Often the engine will not even start.

Diagnosing a Jumped or Broken Timing Mechanism If the engine just spins over fast and does not run at all, you may be able to crank the engine over and look for valvetrain movement through the oil filler cap. If there is no movement, the mechanism is broken. When you cannot see the valvetrain components through the oil fill cap, it may be easiest to pull the upper timing cover off. When a customer said that it was running fine yesterday and today it stopped running and cranks over quickly, a failed timing mechanism is a common cause. One good way to verify a jumped or broken timing mechanism or to confirm your suspicions is to perform a cranking compression test. If the engine is running poorly because of an engine that jumped time, your diagnosis may require a compression test. Crank the engine over, and check each cylinder. When the timing has jumped, the compression will be low on all the cylinders. Frequently it will be as low as 50 psi or 75 psi on every cylinder (Figure 11-3).

Figure 11-2  This snapped timing belt left the customer stranded on the highway. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 11-3  Low compression on most or all cylinders can point to a timing belt/chain that jumped a gear and changed the valve timing.

Figure 11-4  The arrow on the camshaft sprocket and the dot on the cylinder head designate TDC number 1 when they are aligned.

Another quick check for a broken timing mechanism is to check cranking vacuum. Instead of the normal 3–6 in. Hg vacuum, you will see no vacuum if the mechanism is broken. The vacuum will be low if the belt or chain has jumped time. If the engine runs, engine vacuum will be lower than the usual 18–22 in. Hg vacuum found at idle on a healthy engine. SERVICE TIP  A dual trace oscilloscope connected to the crank and camshaft position sensors may be necessary to check for a valve timing problem on a VVT system.

Sometimes when the engine runs fairly well but not correctly, the compression may not be low enough to confirm jumped timing. If you still suspect that the valve timing is off, rotate the engine to top dead center (TDC) number 1 compression using the crankshaft or camshaft indicator. If you can locate TDC on the cam sprocket pretty easily, you may be able to detect TDC of the number 1 piston by a mark on the crankshaft pulley. If there is no mark on the crankshaft pulley, you may still be able to pick out jumped time without removing the crankshaft pulley and accessories. Remove the upper timing cover. Rotate the engine by hand until the TDC number 1 marking is lined up on the camshaft (Figure 11-4). Remove the spark plug from cylinder number 1. Place a straw or a suitable plastic piece on top of the piston. Rotate the engine to ensure that the straw starts declining within a couple of degrees of crankshaft rotation. Rotate the engine two full revolutions, and carefully observe the straw as you approach TDC number 1 on the camshaft. If the timing is on, the piston must reach the top of its travel and stop briefly right when the camshaft timing mark lines up.

TIMING CHAIN INSPECTION To inspect a timing chain for wear, you can measure the amount of movement that the crankshaft makes before the camshaft(s) begins to move. Generally this should be less than 8 degrees, but check the manufacturer’s specifications. Use the crankshaft timing marks when available to watch the degrees of crankshaft movement. Many newer engines do not have timing marks on the crank pulley and front cover, because ignition timing is rarely Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Timing chain

Crankshaft

TDC

Figure 11-5  Rotate the crankshaft backward to get all the slack on one side. Next, measure the rotation before the camshaft moves as you rotate the slack out of the chain.

adjustable now. If that is the case, use a torque angle gauge on a ratchet as you turn the crankshaft. On an older engine that has a distributor, remove the distributor cap and watch for rotor movement as a sign that the chain is rotating the cam or an auxiliary sprocket. When an engine does not use a distributor, it may be possible to detect movement of the camshaft through the oil fill cap. Remove the cap and see if you can clearly view the camshaft or a rocker. If you can, rotate the crankshaft counterclockwise and then clockwise to measure the amount of slack before movement of the cam or valvetrain (Figure 11-5). Sometimes it will be necessary to remove a valve cover to get a good view of the movement of the cam or rockers. If the crankshaft rotates more than 8 degrees before the camshaft moves, the timing chain and/or tensioner is worn beyond usable limits. If you have the timing cover off of a cam in the block engine, you can try to deflect the chain. If you can deflect it less than one-quarter of an inch, the chain is generally satisfactory for continued service as long as the chain itself and the sprockets are in good shape. Deflection of one-half of an inch requires immediate attention. Be sure to consult the service information for the deflection specifications. You can use this same procedure on an overhead cam timing chain by removing the valve cover. Replacement is recommended when there is more than one-half of an inch of deflection or as specified by the manufacturer. Inspect the chain itself for shiny spots on the edges of the chains; sometimes they slap against the metal cover. Look for worn or flat rollers on a roller-type chain. On a flat-link silent chain, look for wear at the attachment pins and joints; shiny spots indicate friction points.

TIMING BELT INSPECTION To inspect a timing belt, you really need to pull the top timing cover off of the engine. This is usually a plastic cover with an upper section and a lower section. For inspection purposes, it only will be necessary to remove the upper cover (Figure 11-6). You will be looking for cracks similar to those in serpentine belts. Rotate the engine around to be able to view the whole belt. Look on the underside of the belt at the cogs or teeth that hold the belt in the sprocket. Any broken or missing teeth dictate immediate replacement. Figure 11-7 shows some typical timing belt failures. If the belt shows signs of oil or coolant contamination, the belt should be replaced and the leak must also be fixed as part of the repair. Be sure to diagnose the cause of the leak and include that procedure and part(s) in your estimate to the customer. As we have discussed, there is no reason to try to eek out another few months on a damaged belt; it could result in a very expensive repair. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Rounded edge

Peeling Tooth missing and canvas fiber exposed

Rubber exposed

Abnormal wear (fluffy strand)

Cracks

Clip

Figure 11-6  Remove the upper timing cover to get a look at the belt. This cover is easily removed with accessible clips.

Peeling

Figure 11-7  Any fault with the belt warrants replacement.

CUSTOMER CARE  Many maintenance manuals provided with new vehicles have a long list of components and systems that are supposed to be inspected at regular intervals. It may be, for example, that at every 60,000 miles when the spark plugs are replaced, the timing belt is also supposed to be inspected. A careless technician may ignore this and other portions of the 60,000-mile service and just replace the new components. A true professional will perform all the tasks recommended by the manufacturer; they are listed for a reason. By performing full service, you will be providing your customers with the excellent quality repair work they are paying for.

TIMING GEAR INSPECTION To check timing gears for excessive wear, remove the timing cover. You should listen before you take the cover off so you will begin to learn what good and bad gears sound like. Put a ratchet on the crankshaft bolt, and rock it lightly back and forth between the backlash of the gears. You do not want to turn it so much that the camshaft actually turns. Just listen for the clacking of the gears. It may be so bad you will know it the very first time, but take the cover off to confirm your diagnosis. Worn teeth will be sharp, shiny, and pointed (Figure 11-8). If you are not sure by visual inspection, you can measure the gear backlash. This is the small clearance left between any gear set that allows room for expansion as the gears heat up. You can measure the clearance between any two teeth. Typical gear backlash is 0.004 to 0.008 in.; you may be able to visually see that this set of gears has more than that. If you are unsure, take Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Rounded edge shows minor wear. Good teeth

Worn teeth

Figure 11-8  Worn teeth develop a sharp pointed edge.

Figure 11-9  This timing chain sprocket was replaced with the chain. Although the wear was not severe, the timing mechanism had a lot of miles on it.

feeler gauges and rock the crank so the teeth are touching and then go backward as far as you can without rotating the camshaft. Measure the clearance between the gears, and compare your reading to the actual specification. Excessive backlash or visual damage to the gears warrants replacement.

SPROCKET INSPECTION Recommended practice is to replace the sprockets used when a timing chain is replaced. The job is not usually a simple one, and the sprockets have typically been in service for over 100,000 miles. The teeth of the sprockets wear with the chain. If you had a low-mileage failure, you would carefully inspect the sprocket teeth. Worn teeth will be shiny and sharper; good sprockets will have an unworn flat spot at the top of the tooth (Figure 11-9). The teeth may actually be rounded on the face from wear with the rollers. Sprockets are not normally replaced when the timing mechanism uses a belt. The belt is very soft compared to the steel sprockets. The sprockets should be inspected, but are not normal wear components. Always check with the manufacturer’s service procedures when inspecting them, however, because in some rare circumstances sprockets have failed. A sharp edge on a timing belt sprocket will cause premature failure of a new belt. Compare each of the cogs to the others, and make sure they are in fine condition. Always check the manufacturer’s TSBs (technical service bulletins) for information about replacing the sprockets. If you have any doubt, replace them.

TENSIONER INSPECTION The timing chain hydraulic-type tensioner is commonly replaced with a high-mileage timing chain job. Again, it makes good sense to take care of all the components in the system. Most tensioners have a minimum length that the plunger should stick out from the body. Refer to the manufacturer’s specifications, and if the plunger length is not within specifications, replace it. You should also check for oil leakage past the front seal from which the plunger protrudes. If you see wetness around the seal, you should replace the tensioner. The pulley-type tensioner used with belts is also commonly replaced when the service interval is long, every 90,000 miles, for example. If the timing belt is being replaced for Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Belt tensioner pulley

Figure 11-10  Replace the belt tensioner pulley if it has excessive mileage or if you can feel any roughness or wobbling in the bearing.

the second time and it was not replaced the first time, you should definitely recommend replacement (Figure 11-10). An engine that requires belt replacement every 100,000 miles deserves a new tensioner to prevent premature failure. To inspect the tensioner for faults, check for scoring on the pulley surface. Scratches, sharp edges, or grooves can damage a new belt rapidly. Also check the pulley’s bearing. Rotate it by hand, and feel for any roughness. If you can hear it scratching or feel coarseness, replace it. Also check the pulley for side play; grasp it on its ends and check for looseness. If it wobbles at all, replace it. A timing belt automatic tensioner is also typically replaced during belt replacement. If there are any signs of oil leakage, replacement is mandatory. If the belt replacement interval is relatively frequent, it may be possible to use the automatic tensioner through the life of two timing belts. The best advice is to follow the recommendation of the manufacturer and carry out any inspections or measurements indicated. SERVICE TIP  Some timing chain sprockets are nylon or plastic coated to quiet them down. If these sprockets are worn, you should remove the oil pan and thoroughly clean the pan and the oil pump pickup screen. The missing fragments are often found in the sump, clogging the oil pickup screen.

TIMING CHAIN GUIDE INSPECTION You should replace the guides on a high-mileage timing chain replacement. They are synthetic rubber or Teflon® or some other material that is much softer than the chain. It is recommended practice to replace the guides. To inspect a guide for wear, look at the surface where the chain rides. If the grooves are deeper or wider or you can see any signs of wear, be safe and replace the guide.

REUSE VERSUS REPLACEMENT DECISIONS When in doubt, replace a worn valve timing mechanism component. A premature failure can cause extensive damage, and you could lose a customer. When you choose to reuse components, make sure you are confident that they will last an appropriate amount of time for the customer and the engine. Your repair work should result in reliable and long-term service. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

TIMING MECHANISM REPLACEMENT The actual repair procedures for service of timing chains, belts, and gears vary immensely. Some OHC timing chains can be replaced in a few hours with the engine in place; others require the engine to be removed from the vehicle. It is common to have to remove the cylinder head and/or timing cover. Timing belts can generally be replaced with the engine in the vehicle. They can be simple and straightforward or time consuming and a little tricky. A timing belt on a transversely mounted V6 engine in a minivan, for example, may leave you little room to access the front end of the engine. Replacing the timing mechanism on cam-in-the-block engines using either a chain or a gear set is usually uncomplicated. In every case, it is critical that you set all the shafts into perfect time with the crankshaft. As we have discussed, setting the valve timing off by one tooth will impact engine drivability and emissions. Similarly, an engine with balance shafts not timed properly will vibrate noticeably. Often it is too easy to miss the timing of a shaft by one tooth if you are not paying close attention and double-checking your work (Figure 11-11). This is an important and time-consuming service work; you want to do it only once! Many technicians will replace the camshaft and crankshaft seals while they have access to them during the job. If the water pump is driven by the timing belt, you will usually replace that as well. Always check idle quality and engine performance after a replacement job to be sure the engine is operating as designed. This text cannot offer a replacement for the manufacturer’s service procedures. Instead it offers a couple of specific examples of the procedures for replacing different timing mechanisms. You will still need manufacturers’ specific information to achieve proper timing mark alignment and to perform the job in the most efficient manner. You may also need special tools to hold the camshaft sprockets in position while replacing the belt or chain(s).

Figure 11-11  This engine has balance shafts. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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CUSTOMER CARE  When repairing an engine with a broken timing mechanism, it is important to know whether the engine is an interference engine or not. If it is, advise the customer of the potentially very high added cost of removing the cylinder head and replacing valves. Also make sure the customer understands that even more serious damage, such as a valve stuck into a piston, could have occurred. Even on free-wheeling engines, it is wise to inform the customer that valve damage is possible. Discuss these issues with the customer or service advisor before offering an estimate for the work.

TIMING CHAIN REPLACEMENT ON OHC ENGINES Replace the timing chain(s) on an engine during a thorough overhaul if noise or symptoms indicate excessive wear, or if the chain has broken. Timing chain replacement procedures vary significantly in the specifics of what must be removed to access the chain and sprockets. You will usually have to remove the valve cover(s), the front engine or timing cover, the engine drive belt(s), any accessories blocking access to the front cover, and the harmonic balancer. Sometimes you will need to remove the front engine mount as well. You must follow the manufacturer’s specific instructions to perform the job most efficiently. Below is a general outline of procedures for replacing the timing chain on a popular double overhead cam (DOHC) engine:

1. Disconnect the negative battery cable. 2. Drain the coolant, and remove the reservoir. 3. Remove the serpentine engine drive belt. 4. Loosen the generator and swing it back out of the way. 5. Remove the upper timing cover fasteners. 6. Remove the engine mount assembly. These bracket bolts may be torque-to-yield bolts and must be replaced with new special bolts. 7. Raise the vehicle, and remove the right wheel. 8. Remove the inner fender splash guard. 9. Use a suitable puller to remove the harmonic balancer. 10. Remove the lower front cover fasteners. 11. Lower the vehicle, and remove the front cover. 12. Rotate the engine clockwise until the camshafts’ keyways are at 12:00 (Figure 11-12). The holes in the camshaft sprocket should line up with the holes in the timing housing. 13. The crankshaft sprocket keyway should be at 12:00 if the valve timing is correct. 14. Remove the timing chain tensioner and guides. 15. Make a front marking on the cam and crank sprockets, using a paint stick or correction fluid, in case they will be reused. 16. Remove the timing chain. 17. Carefully inspect all the components, and determine which, if any, you will reuse (Figures 11-13 to 11-15). 18. Clean the front cover and mating surface thoroughly using a plastic scraper on ­aluminum surfaces. 19. Install the camshaft and crankshaft sprockets with the front markings out. Torque them to the specified value.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Figure 11-12  Line up the timing marks before disassembling the timing chain.

505

Figure 11-13  This chain shows wear on the shiny spots from the friction between the pins and the links.

Figure 11-14  This timing chain guide has a deep groove worn in it from the chain.

Figure 11-15  The tensioner plunger did not protrude the specified length; it was replaced.

20. Make sure the camshaft sprocket holes are still lined up with the holes in the housing. If not, rotate the crankshaft 90 degrees off TDC to provide valve clearance, and turn the cams to line up the holes. Install a dowel through the sprocket into the hole in the timing housing to retain the sprockets (Figure 11-16). 21. Turn the crankshaft backward (counterclockwise) to TDC until the keyway is in the 12:00 position and the marks on the sprocket and the engine block align. 22. Install the chain around the crank sprocket, idler sprocket, and exhaust cam sprocket. Be sure all slack is on the tensioner side of the chain. Remove the intake cam dowel, and rotate the sprocket just a little to install the chain with no slack between the two cam sprockets. Relax the cam, and refit the dowel pin. If it does not slide in, retime the sprocket and chain. All the chain slack must be on the tensioner side. 23. Raise the vehicle, and recheck the crank sprocket alignment marks; adjust as needed.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Dowels

Figure 11-16  Insert the dowels through the sprockets and into the head. This holds the camshafts in perfect alignment while you install the chain.

24. Use a small screwdriver to release the ratcheting mechanism in the tensioner (Figure 11-17). Fully depress the tensioner, and install a retaining pin through the hole in the plunger and housing (Figure 11-18). Install the tensioner and torque to specification. 25. Install the guides and torque properly. Remove the retaining pin in the tensioner. 26. Remove the camshaft dowels, and rotate the engine two complete revolutions. Recheck the alignment marks to be sure they are perfect; adjust as needed (Figure 11-19). 27. Replace the front seal, and lubricate its lip with chassis grease or oil. 28. Reassemble in reverse order using appropriate torque specifications and procedures. 29. Idle the engine, and road test the vehicle to confirm proper performance. SERVICE TIP  When rotating an engine, you should always use the crankshaft bolt rather than the camshaft(s) bolt. You could break a camshaft trying to rotate the engine with it. Also, turn the engine in its normal direction of rotation unless specified otherwise. Engines rotate clockwise when looking at them from the front.

Figure 11-17  Use a tiny screwdriver to release the ratcheting mechanism while you retract the tensioner.

Figure 11-18  Slide a small Allen head or pin through the hole in the tensioner body to retain the tensioner in its retracted position.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service Timing mark

Timing marks must be in position shown with number 1 piston at TDC.

Camshaft mark

Timing mark

Camshaft mark

Timing mark

Figure 11-19  Line up the timing marks exactly as shown in the service information.

As you can see from these instructions, the work of replacing a timing chain requires time, concentration, and attention to the details of valve timing alignment. Follow the manufacturer’s procedures for reinstallation to ensure that all bolts are torqued properly and components are installed correctly.

TIMING BELT REPLACEMENT Check the maintenance manual for the vehicle whenever a vehicle comes to your shop for service. Routine maintenance is often neglected by customers because many expect technicians to inform them when a procedure is due. This is critically important when it comes to timing belt replacement. Many consumers have no idea what a timing belt is, much less that it needs to be replaced periodically. Explain the importance of timing belt maintenance to your customers. Remember that when the timing belt also drives the water pump, it is common practice to install a new water pump when replacing the belt. The safest way to determine if a belt needs replacement is through a visual inspection and by mileage intervals.

CUSTOMER CARE  As a technician, it is important that you read TSBs when performing service work. One manufacturer decided to change the timing belt replacement interval to every 15,000 miles because the belts were snapping so often! Other manufacturers have lengthened the service interval to over 100,000 miles due to improvements in timing belt materials.

The interval on timing belt replacement varies widely. On modern vehicles the typical interval is 100,000 miles or five years. Some new timing belts do not have scheduled replacement. Inspect them at the requested intervals, and replace them when signs of wear are evident. Some older vehicles may require replacement every 30,000, 45,000, or 60,000 miles. All these examples must make it clear that you will need to check the maintenance information to be sure. Timing belts are replaced during a thorough engine overhaul as well. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 11-20  Read through the service information first so you understand the procedure.

To replace the timing belt, you will need to remove the upper and lower timing covers, the harmonic balancer, and any accessories that are in the way of those covers. The procedure will be similar to the timing chain replacement, but the plastic timing belt covers do not seal oil. If the timing belt drives the water pump, this is an excellent opportunity to replace it. Sometimes a timing belt replacement is a pretty quick and simple job. Read through the whole service procedure before beginning so you will be familiar with all the steps required (Figure 11-20). Let us look at a typical example of the procedure to replace a timing belt. Also refer to Photo Sequence 24:

1. Remove the negative battery cable. 2. Remove the accessory drive belts. 3. Lift the vehicle, and remove the right wheel and inner fender splash guard. 4. Remove the engine drive belt(s) and the harmonic balancer using a suitable puller. 5. Lower the vehicle, and support the engine with a jack. 6. Remove the right engine mount and bracket from the engine. 7. Remove the timing belt cover. 8. Rotate the engine to TDC number 1 firing, and note that the marks on the cam and rear timing cover line up. Check the crankshaft sprocket to be sure its notch lines up with the notch on the rear timing cover. (If the engine is equipped with an ­auxiliary or balance shaft, make sure that its marks are also properly aligned [Figure 11-21].) 9. Rotate the tensioner pulley counterclockwise to loosen it until you can slide a small Allen wrench or pin through the locking hole in the pulley and into the hole in the tensioner bracket. This relieves the tension on the belt. 10. Remove the timing belt. Do not rotate the camshaft or crankshaft. 11. Scrutinize the sprockets, tensioner pulley, and water pump; replace components as needed. 12. Install the new components and new timing belt, ensuring that the belt fits tightly around all the components. The slack should be on the tensioner pulley side. 13. Rotate the tensioner pulley just enough to pull out the locking pin. Allow the automatic tensioner to properly tension the belt. Note: Some tensioners are not automatic. On these you will have to loosen the locking nut, rotate the pulley on its eccentric bolt until the proper tension is achieved, and tighten the locking bolt. Use a belt tension gauge to confirm proper tension (Figure 11-22). The belt Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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509

Camshaft

Crankshaft, camshaft, and intermediate shaft marks

Intermediate shaft

Crankshaft

Figure 11-21  Check all the alignment marks before disassembly so you know how they should be lined up during reassembly.

Figure 11-22  Use a belt tension gauge when the tensioner is manual to be sure you make the correct adjustment.

tension gauge fits over the belt and further deflects the needle the tighter the belt is. Read the tension on the gauge, compare to specifications, and adjust as needed. 14. Check the camshaft and crankshaft alignment marks. Rotate the engine two ­complete revolutions, and check the marks again. Adjust as needed (Figure 11-23). 15. Reassemble in reverse order following the recommended procedures. 16. Idle the engine, and road test the vehicle to confirm proper performance.

Figure 11-23  The timing marks should line up perfectly after two revolutions of the engine.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 24

Typical Procedure for Replacing a Timing Belt on an OHC Engine

P24-1  Disconnect the negative cable from the battery prior to removing and replacing the timing belt.

P24-2  Carefully remove the timing cover. Be careful not to distort or damage it while pulling it up. With the cover removed, check the immediate area around the belt for wires and other obstacles. If some are found, move them out of the way.

P24-3  Align the timing marks on the camshaft’s sprocket with the mark on the cylinder head. If the marks are not obvious, use a paint stick or chalk to mark them clearly.

P24-4  Carefully remove the crankshaft timing sensor and probe holder.

P24-5  Loosen the adjustment bolt on the belt tensioner pulley. It is normally not necessary to remove the tensioner assembly.

P24-6  Slide the belt off the camshaft sprocket. Do not allow the camshaft pulley to rotate while doing this.

P24-7  To remove the belt from the engine, the crankshaft pulley must be removed. Then the belt can be slipped off the crankshaft sprocket.

P24-8  After the belt has been removed, inspect it for cracks and other damage. Cracks will become more obvious if the belt is twisted slightly. Any defects in the belt indicate that it must be replaced. Never twist the belt more than 90 degrees.

P24-9  To begin reassembly, place the belt around the crankshaft sprocket. Then reinstall the crankshaft pulley.

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PHOTO SEQUENCE 24 (CONTINUED)

P24-10  Make sure the timing marks on the crankshaft pulley are lined up with the marks on the engine block. If they are not, carefully rock the crankshaft until the marks are lined up.

P24-11  With the timing belt fitted onto the crankshaft sprocket and the crankshaft pulley tightened in place, the crankshaft timing sensor and probe can be reinstalled.

P24-13  Adjust the tension as described in the service manual. Then rotate the engine two complete turns. Recheck the tension.

P24-12  Align the camshaft sprocket with the timing marks on the cylinder head. Then wrap the timing belt around the camshaft sprocket, and allow the belt tensioner to put a slight amount of pressure on the belt.

P24-14  Rotate the engine through two complete turns again, and then check the alignment marks on the camshaft and the crankshaft. Any deviation needs to be corrected before the timing cover is reinstalled.

SERVICE TIP  A timing belt that is adjusted too tightly will make a whining or whirring noise when you start the engine up. Do not be tempted to let it “break in”; it could easily snap or damage the engine or water pump bearings.

CUSTOMER CARE  Do not omit what seem like little details on a job. It is critical that you replace the plastic timing covers securely on the engine. They keep debris off the belt, but they also prevent water or ice from leaking in. If ice or even a lot of water gets onto the belt, it can skip teeth even when it is relatively new and properly tensioned. This has happened many times to careless technicians. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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TIMING CHAIN OR GEAR REPLACEMENT ON CAMSHAFT-IN-THE-BLOCK ENGINES Replace an in-the-block timing chain or gear set when an engine is overhauled, when excessive wear is detected, or after the mechanism fails. Rotate the engine to TDC number 1 using the mark on the harmonic balancer. To access the timing mechanism, you will generally have to disconnect the negative battery clamp and remove the cooling fan if it is mounted on the water pump snout. You may have to drain the coolant and remove the water pump; if you do, look over the pump closely and replace it if it has defects or extended mileage on it. Remove the engine drive belts. Use a puller (generally) to remove the crankshaft pulley and any other accessories or brackets that may be blocking access to the timing cover bolts. Remove the timing cover bolts and timing cover, and note the markings—usually small dots, notches, or lines—on the gears or sprockets. Inspect the chain or gears for damage so you are confident that your diagnosis will repair the original concern. Examine the sprockets for the timing chain; they are typically replaced with the chain. Scrape the timing cover and mating surface clean. Replace the gears or chain and sprockets (Figure 11-24). When replacing a timing chain, place the chain around the sprockets, and adjust the sprocket until the timing marks line up; then reinstall the sprockets onto the crankshaft and camshaft. With gears, mate them together so the timing marks are aligned, and then slide them over the shafts (Figure 11-25). In both cases, the shafts will have to be properly set up so the gears or sprockets will fit over the keys on the camshafts and crankshafts. Rotate the engine two full revolutions, and be sure that the marks line up perfectly. Reinstall the timing cover with a new gasket and any recommended sealant. Torque the bolts in the designated sequence; this is typically in a diagonal fashion around the cover. Reassemble the rest of the components, and verify proper engine performance.

Figure 11-24  Fit the chain over the sprockets so the alignment dots point toward each other.

Figure 11-25  Slide the sprockets over the shafts with the marks aligned. Recheck the marks after two engine revolutions.

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TIMING CHAIN REPLACEMENT ON ENGINES WITH OHC AND BALANCE SHAFTS There is no room for error in replacing the timing chains on an engine with overhead camshafts and balance shafts. The valve timing must be perfect for the engine to perform properly and achieve good fuel economy and proper emissions. The balance shafts must be timed precisely to prevent engine vibration. There is no substitute for the manufacturer’s service information. Make sure you have any special tools required to perform a professional job. In some cases you will have to remove the engine from the vehicle to perform the job. In other cases, you can perform the work with the engine in the vehicle. To make the job simplest, place the engine at TDC number 1 firing, remove the timing cover, and make a careful note of the timing marks. This will help you during the reassembly process. Carefully inspect for wear of all the timing chain components: guides, tensioners, sprockets, and chains. Refer to Photo Sequence 25.

PHOTO SEQUENCE 25

Typical Procedure for Replacing Timing Chains on a DOHC Engine with Balance Shafts

P25-1  Set the engine at TDC number 1 ­compression, and remove the valve cover and crank pulley.

P25-2  Remove the timing cover.

P25-4  Remove the camshaft sprockets and chain.

P25-5  You may need to remove the cylinder head to access all the guides. Remove the guides and primary chain.

P25-3  Remove the tensioner, do not allow the engine to rotate, and loosen the camshaft sprockets.

P25-6  The secondary chain runs the balance shafts and water pump. Remove, inspect, and replace any worn guides. It is common practice to replace guides, sprockets, chains, and tensioners when replacing chains on a highermileage engine.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 25 (CONTINUED)

P25-7  Align the balance shafts and crankshaft sprockets exactly as shown in the service manual. To set the chain up, you compress the tensioner and install a pin to relieve pressure. When all is lined up, remove the pin to tension the chain.

P25-8  Rotate the engine two complete revolutions, and be sure that the timing marks line up perfectly.

P25-9  Install the crankshaft sprocket for the primary chain.

P25-10  Line the chain up on the camshaft sprocket in its correct position, and torque the sprocket to specification.

P25-11  With the primary chain installed, check the alignment marks on the camshaft and crankshaft sprockets.

P25-12  Torque the tensioner, and rotate the engine another two revolutions to recheck your timing marks. You want to do this job only once.

P25-13  Reassemble the engine using the proper torque specifications, gaskets, and ­sealants if required.

Because the task is usually a time-consuming and expensive proposition, most technicians will replace those components just listed. Never be satisfied with “close enough” when it comes to lining up the timing marks; this is a job you want to do only once! Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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TIMING CHAIN REPLACEMENT ON ENGINES WITH VVT SYSTEMS To successfully replace the timing chain(s) on a VVT engine, you will need to closely follow the manufacturer’s procedure and have access to any special tools required. The Cadillac VVT system uses three timing chains to drive the four overhead camshafts. The primary chain drives each intermediate camshaft sprocket. A chain is used, one on each head, from the intermediate sprocket to drive the top camshaft sprockets with the ­camshaft position actuators. The actual procedure is not dramatically different from other timing chain replacements, but there are more steps because of the multiple chains. What follows is a simplified outline of the steps to replace the timing chain on the Cadillac VVT engine. 1. Place the engine at TDC number 1 on the compression stroke. 2. Remove the camshaft covers (Figure 11-26). You will need to remove the brake booster vacuum hose, the fuel injector sight shield, and the positive crankcase ventilation (PCV) tube from the left cover. Also remove the ignition module, the camshaft sensors, the ground strap on the left cover, and the dipstick tube securing bolt. 3. Remove the front timing cover and oil pump. 4. Install the special camshaft holding tools to the backs of the camshafts to prevent them from rotating. 5. Use a paint stick to mark the location of the black links of the chains in relation to the timing marks on the camshaft actuators and intermediate sprockets (Figure 11-27). 6. Remove the bolts attaching the timing chain tensioners. They will expand as you remove them (Figure 11-28). 7. Remove the timing chains, camshaft actuators, and sprockets. 8. Clean and inspect all components, and replace any parts that show signs of wear, such as scoring; rounded edges; or shiny, sharp teeth. 9. Reinstall the camshaft actuators and sprockets, with the timing marks positioned according to the manufacturer’s diagrams. 10. To reassemble with a new chain, locate the black links and reposition them in the same locations on the sprockets (Figure 11-29). 11. Align the timing marks as indicated by the manufacturer’s diagrams (Figure 11-30). 12. Compress and lock the timing chain tensioners, and reinstall them using the proper torque specification (Figure 11-31). 13. Release the tensioners, and recheck the timing marks. Adjust as needed. 14. Rotate the engine two complete revolutions, and confirm that the timing marks are properly aligned. 15. Reassemble the engine, and check for oil leaks, proper idle, and quality engine performance.

A camshaft position actuator is a hydraulically actuated device that changes the camshaft in relation to the crankshaft.

Black links

Alignment marks

Figure 11-26  Remove the camshaft cover.

Figure 11-27  Use a paint stick to mark the black links and the alignment marks on the sprockets.

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Chapter 11 Chain tensioner

Secondary chain

Black links

Black link

Figure 11-29  Use the black links on the new chain to align with the marks on the sprockets.

Figure 11-28  Remove the timing chain tensioners.

3

4

Lever

1

2 Figure 11-30  The upper numbers 3 & 4 show the black links aligned with the marks on the camshaft sprockets. The numbers 1 and 2 on the intermediate and crankshaft sprockets show those alignment marks.

Figure 11-31  Collapse the lever to retract the tensioner; then hold the lever down to retain the tensioner until it is installed. Sometimes a pin can be installed to hold the ratcheting mechanism back.

Removing Camshafts and Rocker Arms, DOHC Engine with VTEC Before removing the camshafts on a DOHC engine with variable timing electronic control (VTEC), the timing belt must be removed, as we will discuss. Follow this procedure to remove the camshafts: 1. Remove the pulley to camshaft retaining bolts on each camshaft, and remove the camshaft pulleys (Figure 11-32). Identify each pulley so it is reinstalled in its original location. 2. Identify all camshaft holder plates and camshaft holders so they will be reinstalled in their original locations. Loosen the rocker arm locknuts and adjusting screws, Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service Camshaft holder plate Camshaft holders

Camshaft sprockets

Retaining bolts Oil seal

Figure 11-32  Removing the camshaft pulleys.



Figure 11-33  Removing camshaft holder and holder plates.

and then remove the retaining bolts in the camshaft holder plates and camshaft holders (Figure 11-33). 3. Remove the camshafts from the cylinder heads. 4. Remove the retaining bolt on each rocker shaft oil control orifice, and pull out the oil control orifices (Figure 11-34). 5. Remove the VTEC solenoid from the cylinder head, and then remove the sealing bolts from the cylinder head (Figure 11-35). 6. Place an elastic around each triple set of rocker arms to keep them together. Identify all rocker arm sets or lay them out in order after removal, because they must be reinstalled in the original positions. 7. Screw a 12 3 1.25-mm bolt into each rocker arm shaft, and pull these shafts from the cylinder heads toward the transmission end of the engine (Figure 11-36). 8. Remove the rocker arm sets from the cylinder head.

Measuring Camshaft End Play and Camshaft Bearing Clearance, DOHC Engine with VTEC Follow these steps to measure the camshaft end play: 1. With the rocker arms removed, place the camshafts in their original positions on the cylinder head. Be sure the camshaft journals and bearing surfaces are clean. 2. Place a light coating of the engine manufacturer’s specified oil on the camshaft holder and holder plate bolt threads. Install the camshaft holders, holder plates, and retaining bolts. Tighten these bolts in the proper sequence to the specified torque. 3. Mount a dial indicator so that the indicator stem contacts the front of the camshaft (Figure 11-38). With the camshaft pushed rearward, zero the dial indicator. 4. Pull the camshaft forward, and read the end play on the dial indicator. 5. Remove the camshaft holder plates and holders, and place a plastigage strip across each camshaft journal. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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O-ring

O-ring Filter

Rocker shaft oil control orifices

Washer

VTEC solenoid valve Sealing bolt

Figure 11-35  Removing VTEC solenoid and sealing bolts.

Figure 11-34  Removing rocker shaft oil control orifices.

Rubber band

Rocker arm assembly

12-mm bolt

Figure 11-36  Removing rocker arm shafts.

Special Tools Outside micrometer V-blocks Dial indicator Pushrod adapter

Figure 11-37  Measuring camshaft end play.

6. Install the camshaft holders and holder plates, and tighten the retaining bolts in the proper sequence to the specified torque. 7. Remove the camshaft holders and holder plates, and measure the plastigage width to determine the camshaft bearing clearance (Figure 11-38). 8. If the camshaft bearing clearance is more than specified, and the camshaft has been replaced, the cylinder head must be replaced. If the camshaft has not been replaced, remove the camshaft, and measure the camshaft runout. If the runout is within specifications, replace the cylinder head. When the runout is not within specifications, replace the camshaft, and recheck the bearing clearance.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service Plastigage strip

Rocker arm pistons

Primary

Plastigage measure

Mid

Secondary

Figure 11-38  Measuring camshaft bearing clearance.

Figure 11-39  Inspecting VTECH rocker arms.

Inspecting and Servicing Rocker Arms and Shafts with VTEC Inspect the contact pad on all rocker arms for scoring and wear. Then inspect the rocker arm pistons for scoring and free movement in the rocker arms (Figure 11-39). Scored or sticking pistons require rocker arm and piston replacement. Inspect the rocker arm shafts for wear and scoring. Shafts that are visibly worn and/or scored must be replaced. Measure the rocker arm shaft diameter with a micrometer in the first rocker arm position on one end of the shaft. Install a bore gauge in the micrometer with the micrometer set at the rocker arm shaft diameter, and zero the bore gauge (Figure 11-40). Install the bore gauge in the matching rocker arm opening, and determine the rocker arm to shaft clearance by reading the amount the gauge pointer moved from the zero position (Figure 11-41). Repeat this procedure for all the rocker arms. Replace any rocker arms and shafts if this clearance is not within specifications. Bore gauge

Measure rocker arm bore.

Micrometer

Figure 11-40  Transferring rocker arm shaft diameter reading from a micrometer to a small bore gauge.

Inspect rocker arm face for wear.

Figure 11-41  Measuring rocker arm bore.

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SERVICE TIP  If correction is done by milling or shimming the rocker arm stand, alter the stand height one-half the total amount needed at the stem tip.

Checking an Active Fuel Management or Variable Cylinder Displacement System for Proper Operation Special Tools Compression Tester Scan Tool

This type of check can be done by performing a compression test on all the cylinders. Use a bidirectional scan tool to activate the solenoids for every individual cylinder while measuring that cylinder’s compression. There should be a notable difference (approximately 50 psi). No noticeable difference indicates a malfunction in the electrical or hydraulic circuit for that cylinder and will have to be further checked for opens, shorts, solenoid, lifter, or ECM faults.

Diagnosing Active Fuel Management or Variable Cylinder Displacement Systems Follow these steps to diagnose active fuel management or variable cylinder displacement systems:

Special Tools DMM Scan Tool

1. Check the condition and level of the engine oil. 2. Use a scan tool to check for Engine Control Module DTCs and look for any related TSBs. 3. If any TSBs or DTCs are located, follow the manufacturer’s chart to diagnose the condition. 4. If no related TSBs or DTCs are found, check for proper oil pressure. 5. If oil pressure is within specifications, then verify proper operation of system components using a bidirectional scan tool or by using the manufacturer recommended tester. 6. If any components are not operational, then remove the solenoid assembly. Check the resistance on the bench of the solenoids and compare them to the manufacturer’s specifications. 7. If they do not meet specifications, replace the solenoids. If the solenoids meet specifications, replace the lifters as needed. 8. Clean the oil passages, change the oil and filter, and confirm proper operation. CUSTOMER CARE  When servicing an engine with variable cylinder displacement, variable valve timing, or variable lift systems, make sure to use the proper oil and filter. Most system malfunctions can be traced back to the oil and filter not being serviced on time, a lack of oil service all together, driving with a low oil level, using the incorrect viscosity oil during service, or installing an inadequate oil filter. Most system actuators have filter screens that can be inspected for debris that could indicate an oil service–related problem. If necessary, remind the customer of the importance of checking the oil level and having the oil system serviced on time.

CASE STUDY A student was traveling back to college in Colorado from her home in Vermont. She had just had her older vehicle serviced and a new timing belt installed. It seemed to run fine, and she made it to Colorado without any trouble. When she went for her emissions test, however, the engine failed for high CO and HC levels. It took a technician a few hours to figure out that the timing belt was off one tooth, and it took a few more hours to repair it.

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ASE-STYLE REVIEW QUESTIONS 1. Technician A says that generally a timing chain is replaced every 60,000 or 90,000 miles. Technician B says that typically the timing chain is replaced during a major engine overhaul. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. The best way to properly determine if a timing belt needs replacement is to: A. ask the customer when it was last done. B. look at the maintenance information to ­determine the recommended interval. C. remove the top timing cover to inspect the condition of the belt. D. replace it at every tune-up to be safe. 3. Technician A says that the timing chain is removed before the tensioner. Technician B says that to install the tensioner, you have to lock the plunger into the body. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 4. Technician A says that a VTEC engine should have zero camshaft end play. Technician B says that you should check the camshaft bearing clearance on a VTEC engine with plastigage. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that the timing chain cover seals oil in. Technician B says that the plastic timing belt ­covers can be left off if they crack during removal. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. Technician A says that after a timing mechanism replacement you need to rotate the engine two complete revolutions to make a final check of the timing marks. Technician B says that you should always road test a vehicle after a timing mechanism replacement. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. Technician A says that an engine with a worn ­timing belt will run better just before it breaks. Technician B says that low-end acceleration may deteriorate with a worn timing chain. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that worn timing gears may clatter on acceleration or deceleration. Technician B says to verify worn timing gears by checking for excessive end play. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 9. Technician A says that timing chain tensioners are typically replaced with the chain. Technician B says that you should measure the timing chain tensioner’s spring tension to determine if it can be reused. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that timing chain guides should last the life of the engine. Technician B says that worn timing belt pulleys will show scoring and/or roughness in the bearing. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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ASE CHALLENGE QUESTIONS 1. Technician A says that being off on valve timing as little as three teeth can result in valve-to-piston contact. Technician B says that advancing the camshaft one tooth will improve high rpm breathing. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that most engines are timed at BDC of the compression stroke for cylinder ­number 1. Technician B says that valve timing should be adjusted every 60,000 miles. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Each of the following is a likely symptom of a valve timing problem except: A. Detonation C. Rough idle B. Backfiring D. Poor fuel economy 5. Technician A says that you have to remove the engine to replace the timing mechanism on a variable valve timing system. Technician B says that the camshaft actuators must be properly timed during reassembly. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. Technician A says that you may need to use a block of wood to hold the camshafts in place when replacing the timing chains. Technician B says that if the crankshaft rotates less than 20 degrees before the camshaft moves, the chain is acceptable. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Name ______________________________________

Date __________________

INSPECTING, REMOVING, AND REPLACING A TIMING CHAIN OR BELT Upon completion of this job sheet, you should be able to properly inspect the timing chain or belt. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.6.

Remove and replace timing belt; verify correct camshaft timing.

This job sheet addresses the following MLR task for Engine Repair: A.5.

Remove and replace timing belt; verify correct camshaft timing.

Tools and Materials • Service manual • Technician’s tool set • Torque wrench Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure Using an assigned engine and the proper service manual, you will identify and perform the required steps to inspect the valvetrain timing chain or belt. 1. Does your assigned engine use a timing belt or a timing chain? ____________________ 2. What page of the service manual covers the procedure for checking timing belt or chain wear? ________________________________________________________________ 3. What is the specification for chain or belt deflection? _____________________________ 4. What is the measured deflection? _____________________________________________ 5. If a chain and sprocket system is used on your engine, inspect the camshaft and crankshaft sprockets for wear and damage. Record your findings. _________________________________________________________________________ _________________________________________________________________________ 6. If a timing belt is used on your engine, inspect it for cracks and separations. Note any defects. _________________________________________________________________________ 7. If your engine uses a timing belt, what type of belt tensioner is used? 

Hydraulic h Mechanical h

8. Inspect the tensioner, and note any defects. _________________________________________________________________________ 9. Based on your inspection, what is your recommendation? _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

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Chapter 11

10. The service directions for removing timing chains and belts are different for each engine. Go to the service manual, and briefly outline the specific procedure in the space below.

11. Use the space below to write down the torque specifications for the components you will need to reinstall.

12. Follow the manufacturer’s service manual removal directions to remove the belt or chain. While you are in the process of the removal of components, take note of the condition of the following components. Make a note if they should be replaced. Component

Condition

Component

Water Pump

Seals

Tensioner

Cover

Pulleys/Gears

Other

Condition

13. Follow the manufacturer’s service manual installation directions to install the belt or chain. Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Name ______________________________________

Date __________________

INSPECTING THE VARIABLE VALVETRAIN TIMING COMPONENTS Upon completion of this job sheet, you should be able to properly inspect the timing components of a variable valvetrain engine. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.5. Inspect and replace camshaft and drive belt/chain; includes checking drive gear wear and backlash, end play, sprocket and chain wear, overhead cam drive sprocket(s), drive belt(s), belt tension, tensioners, camshaft reluctor ring/tone wheel, and valve timing components; verify correct camshaft timing. Tools and Materials • Service manual • Technician’s tool set Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure 1. Using the service manual, list all of the variable valvetrain components that are used in the engine you are working on. _________________________________________________________________________ _________________________________________________________________________ 2. Inspect the tone wheel for cracks and damage. What did you find? _________________________________________________________________________ 3. Inspect the tone wheel position sensor for damage to the sensor itself, the seal, and the wiring harness. What did you find? _________________________________________________________________________ 4. If the engine is equipped with a specific oil filter or screen for the VVT system, inspect it for dirt, grease, sludge, and damage. What did you find? _________________________________________________________________________ 5. Rotate the crankshaft, and check the timing marks on the chain. Do they line up? _________________________________________________________________________ 6. Based on your inspections, what services do you recommend? _____________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

70

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Name ______________________________________

Date __________________

527

JOB SHEET

71

OHV VALVETRAIN TIMING Upon completion of this job sheet, you should be able to time the valvetrain on an OHV engine properly. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.6.

Establish camshaft position sensor indexing.

Tools and Materials • Service manual • Technician’s tool set • Torque wrench • OHV engine Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Using an assigned engine and the proper service manual, you will identify and perform the required steps to time the valvetrain on an OHV engine. 1. What page of the service manual covers the procedure for setting valve timing? _________________________________________________________________________ 2. Align the timing marks so the engine is at TDC. How do you know when TDC is obtained? _________________________________________________________________________ _________________________________________________________________________ 3. Following the service manual procedure, remove the timing chain and sprockets. 4. Inspect the camshaft sensor magnet or position indicator. Is it damaged? _________________________________________________________________________

h

5. Install the new chain over both the camshaft sprocket and crankshaft sprocket. Describe how you were able to line up both sprockets (or gears). _________________________________________________________________________ _________________________________________________________________________ 6. Align the timing marks to their proper location. 7. Following the service manual procedure; install the chain and sprockets. 8. What is the torque specification for the camshaft sprocket bolt? _________________________________________________________________________

h h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Name ______________________________________

Date __________________

529

JOB SHEET

72

SOHC VALVETRAIN TIMING Upon completion of this job sheet, you should be able to time the valvetrain on an SOHC engine properly. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.6.

Establish camshaft position sensor indexing.

Tools and Materials • Service manual • Torque wrench • Technician’s tool set • SOHV engine Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Using an assigned engine and the proper service manual, you will identify and perform the required steps to time the valvetrain on an SOHC engine. 1. What page of the service manual covers the procedure for setting valve timing? _________________________________________________________________________ 2. Align the timing marks so the engine is at TDC. How do you know when TDC is obtained? _________________________________________________________________________ _________________________________________________________________________ 3. Following the service manual procedure, release the belt tension.

h

4. Following the service manual procedure, remove the timing belt.

h

5. While preventing the camshaft from rotating, remove the camshaft sprocket.

h

6. While preventing the crankshaft from rotating, remove the crankshaft sprocket. List any special tools required to remove this sprocket. _________________________________________________________________________ _________________________________________________________________________ 7. Install the camshaft sprocket. What is the torque specification for the sprocket bolt? _________________________________________________________________________ _________________________________________________________________________ 8. Install the crankshaft sprocket. List any special tools required to install the sprocket. _________________________________________________________________________ _________________________________________________________________________ 9. Following the service manual procedure, install the timing belt.

h

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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10. Briefly describe the procedure for adjusting belt tension. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Timing Mechanism Service

Name ______________________________________

Date __________________

DOHC VARIABLE VALVE TIMING Upon completion of this job sheet, you should be able to understand the procedure for ­service of a timing mechanism on a DOHC engine with variable valve timing. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: B.6.

Establish camshaft position sensor indexing.

Tools and Materials • Service information • Technician’s tool set • Torque wrench • VVT engine Describe the vehicle being worked on: Year _____________________ Make ______________________ Model ____________________ VIN ____________________________ Engine type and size _____________________________ Procedure 1. Using a suitable form of service information, locate the description of operation about the variable valve timing system. 2. In a few sentences, describe the basic operation of the system. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Read through the service procedure. List any special tools required to perform a replacement of the timing chain. _____________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. Briefly outline the steps to remove the timing chains(s). 1. ______________________________________________________________________ 2. ______________________________________________________________________ 3. ______________________________________________________________________ 4. ______________________________________________________________________ 5. ______________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

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6. ______________________________________________________________________ 7. ______________________________________________________________________ 8. ______________________________________________________________________ 9. ______________________________________________________________________ 10. ______________________________________________________________________ 11. ______________________________________________________________________ 12. ______________________________________________________________________ 13. ______________________________________________________________________ 14. ______________________________________________________________________ 5. Describe the procedure to time the camshaft sprockets, intermediate shafts, and crankshaft sprockets. Use a diagram if needed. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. What is the torque specification for the crankshaft sprocket? _____________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 12

INSPECTING, DISASSEMBLING, AND SERVICING THE CYLINDER BLOCK ASSEMBLY

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■ ■■

■■

■■

■■ ■■

How to properly disassemble the engine block. How to clean the engine assembly and individual components. How to perform a complete visual inspection of the cylinder block and determine needed repairs. How to properly measure the cylinder block for deck warpage and other damage. How to measure and evaluate the cylinder bores for taper and out-of-round. How to properly refinish cylinder bores. How to measure the main bore for wear or misalignment and determine needed repairs.

■■

■■ ■■

■■ ■■ ■■ ■■

How to perform a thorough visual inspection of the crankshaft and determine needed repairs. How to accurately measure crankshaft warpage. How to measure the journals, seal diameters, flange, and vibration dampener mating surface of the crankshaft for wear and determine needed repairs. How to remove core plugs and gallery plugs for engine cleaning. How to properly remove and inspect the harmonic balancer. How to inspect the flywheel and determine needed service. How to evaluate the engine block to determine if repairs or replacement would be more economical.

Terms To Know Align honing Cylinder boring Deck Dry sleeves Harmonic balancer Impact screwdriver

Interference fit Line boring Magnafluxing Out-of-roundness Peening Pilot bushing

Polished Ring ridge Sleeving Taper Total indicator reading (TIR) Wet sleeves

INTRODUCTION The engine disassembly procedure is an important part of your engine repairs. Work like a detective, carefully inspecting each component as it is removed. You need to pay attention to all the clues to ensure that you find every fault and each potential problem during your service. You should have to remove an engine only once to make all the necessary repairs. Speed is not the most important factor when disassembling the engine. It will come apart easily, but your organization is what will allow you to put it back together efficiently as well. Separate and label bolts, and mark brackets. Write down problems as you see them so you will remember to repair them and you can also refer to them when you evaluate the extent of the damage. Save the old parts and gaskets until the overhaul is complete. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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You may need to compare new parts to the old parts, and the customer may want to look at damaged components. When you are replacing an engine, it is easiest to have the replacement engine next to the old one. That will make it clear which components need to be transferred to the new engine and will show you how they are mounted.

ENGINE PREPARATION

The harmonic balancer attaches to the front of the crankshaft and reduces torsional vibrations.

Make sure that the engine is well secured on the engine stand (Figure 12-1). Before beginning the engine disassembly, clean the outside of the engine well enough so you will not be getting dirt or grime into it. Make a clean work area for yourself with enough room to lay parts out for examination and proper storage. Many parts when reused will have to be installed back into their original location. Have coffee cans, plastic containers with lids, or plastic bags available for storing the many sets of bolts you will remove. Use masking tape and a permanent marker for labeling (Figure 12-2). Do not mix bolts from the oil pan, valve cover, timing cover, rockers, and main and rod caps into one big bin. Digging through a pile of bolts trying to find the correct ones is not an efficient or reliable way to reassemble an engine. Spray the exhaust manifold studs, the crankshaft snout to ­harmonic balancer seam, and any other rusty bolts with penetrating oil, and allow it to soak while you proceed. Follow the manufacturer’s procedure for complete disassembly instructions. It will provide torque sequences for removing major components such as the head, main caps, and intake manifold. SERVICE TIP  The best engine repair technician I have met took some ribbing for how much time he spent disassembling the engine. He carefully marked each set of bolts or threaded them lightly back into place; everything was very well organized. Not once in the years I worked with him did he have an engine come back for as much as an oil leak or a rattle.

Figure 12-1  This high-mileage, late-model, turbo-charged engine is already in need of an overhaul.

Figure 12-2  Separate and label the bolts to help yourself with reassembly. Many parts such as lifters and rocker arms should be reinstalled in their original locations if they are to be reused.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

CYLINDER HEAD REMOVAL You can remove the cylinder head with the engine either in or out of the vehicle. The procedure is similar with the engine installed. You may have to remove some of the hoses, connections, and cables that we discussed in engine removal to gain access to the valve cover(s) and head(s). Be sure the engine is cool when loosening intake or head bolts to prevent warpage. The following is a general outline of the procedure to remove a cylinder head: 1. Remove the intake manifold using the reverse of the tightening sequence (unless a loosening sequence is provided). You can usually leave the injectors, fuel rail, and pressure regulator attached to the manifold. On some V-type engines, you will have to remove the pushrods before you can lift the manifold out (see step number 5). 2. Remove the exhaust manifold(s). In some areas of North America, the exhaust studs and nuts may be quite rusty (Figure 12-3). You will usually replace the studs, but it is easier to remove them if they are not broken. Many times it is safest to use some heat on the nuts before attempting to loosen them. 3. Remove the valve cover(s). 4. If the engine has an overhead cam, you will have to remove the timing belt or chain. Rotate the engine to TDC number 1, and locate the timing marks on the camshaft(s) pulley(s). Make notes about the TDC markings to facilitate installation. Some manufacturers call for removal of the timing cover to access the tensioner. On other vehicles, it is possible to remove the tensioner from the outside of the cover. Release the tension on the chain or belt. Remove the camshaft sprocket from the camshaft and inspect it for wear. 5. On an engine with the camshaft in the block, loosen the rocker arms and remove the pushrods. It is a good idea to mark their position so they can be installed in the same location. Inspect the pushrods for bends or wear. 6. Remove the lifters from their bores. If you might reuse them, mark their correct location with a marker or masking tape; they should be returned to their original bore and contact the same lobe on the camshaft. The lifters can be sticky in their bores; a special tool can help remove them (Figure 12-4).

Figure 12-3  These exhaust manifold nuts will require heat to loosen them. Replace the studs while the cylinder head is off. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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10

4

2

6

8

7

5

1

3

9

Front

Figure 12-4  This lifter removing tool can help remove sticky lifters without damaging the lifter or the bore.

Figure 12-5  Reverse this tightening sequence to loosen the head bolts.

7. If you are working on a V-type engines, mark the cylinder heads left and right. Left and right are determined by looking at the engine from the flywheel end. 8. Loosen the head bolts using the loosening sequence. If one is not specified, use the reverse of the tightening sequence (Figure 12-5). Check for any differences in the bolts, and if they differ, mark their proper locations. If the bolts are to be reused, clean them and inspect the threads for damage. On many newer engines, the manufacturers use torque-to-yield bolts and specify replacement after one use. 9. Knock the cylinder head(s) with a plastic dead blow hammer to try to loosen it. You may have to use a pry bar to release the head. Be careful not to damage the sealing surface of the head. If the head does not pry off easily, check to be sure all the bolts are removed. Use the service information to locate all the cylinder head bolts to prevent damaging the head. 10. Remove the cylinder head and gasket. Carefully inspect the gasket for signs of leakage or detonation. Detonation will often distort the steel fire ring on the gasket that surrounds the cylinder bore. SERVICE TIP  One time a new technician had a V6 engine almost fully put together after an overhaul. He started putting the brackets and accessories back on, but two of the brackets would not bolt up. On one head, there were no mounting holes showing at all. After a period of frustration, he realized the heads were installed on the wrong sides.

TIMING MECHANISM DISASSEMBLY To uncover the timing mechanism, you will have to disassemble the front end of the engine, including the timing cover, any remaining accessories or brackets, and the harmonic balancer. Remember to mark the position and bolts for brackets and accessories. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Removal of the harmonic balancer can be a challenging project. This straightforward operation has turned many simple repairs into a daylong exercise. Improper removal procedures can lead to crankshaft damage and the need for expensive replacement. In most cases, a front pulley is attached to the harmonic balancer to drive the accessory belt(s) (Figure 12-6). Remove the bolt and washer that retain the harmonic balancer (Figure 12-7). The harmonic balancer can be designed as a slip fit or an interference fit. Slip-fit balancers are simply removed by sliding (or gently prying) the balancer off. A key or flat area on the crankshaft prevents rotation of the pulley on the crankshaft. Most harmonic balancers are interference or press fit onto the end of the crankshaft. A bolt may also be used, and it may be necessary to use a flywheel holding tool to keep the engine from spinning. Use a puller to remove the harmonic balancer (Figure 12-8). It is important to place a spacer between the threaded end of the puller and the crankshaft. If you fail to do this, the puller threads can thread into the crankshaft and seriously damage it. Usually holes are threaded in the end of the balancer, so you can mount the puller to the balancer and then push on the crankshaft. Sometimes you will have to use jaws on the outside of the balancer (Figure 12-9). In either case, be sure to protect the internal threads of the crankshaft. Install a spacer button on the end of the crankshaft so the puller cannot thread into the crank.

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Interference fit ­components are slightly smaller than the shaft they fit onto or the bore they fit into. This makes a puller or a press necessary for disassembly and reassembly.

Crankshaft vibration damper

Crankshaft pulley

Attachment bolt

Balancer

Figure 12-6  Removing the crankshaft pulley.

Figure 12-7  Remove the attaching bolt before pulling the ­balancer off.

Insert Puller

Figure 12-8  The right puller makes short work of pulling the balancer off safely.

Figure 12-9  Some balancers require the use of a ­jaw-type puller.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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SERVICE TIP  Many late-model overhead camshaft engines have complex timing chain mechanisms and variable cam timing components that require special service tools and procedures. Refer to the manufacturer’s specific procedures before disassembling the timing mechanism.

With the balancer off, remove the timing cover. Be sure to mark where bolts go when they are different lengths; you may want to insert them into the proper hole of the cover and tape them into place. If the oil pump is mounted on the front of the crankshaft, remove it and set it aside for evaluation later (Figure 12-10). You may have to remove brackets, accessories, or the water pump to access the timing cover (Figures 12-11 and 12-12). Before disassembling the timing mechanism, rotate the engine to TDC number 1 compression so that the timing marks line up (Figure 12-13). It is helpful to see how the marks should line up when the timing is correct. Check the

Figure 12-10  This crank-driven oil pump must be removed before the bottom end can be disassembled.

Figure 12-11  Removing the water pump to access the timing cover. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

539

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly Cam sprocket timing mark

Water pump

Arrow on rear cover

Timing cover Tensioner pulley

Front cover gasket

TDC reference mark

Cylinder block TDC mark

Figure 12-12  In some cases, it is faster to remove the water pump and timing cover together. If the job is a thorough overhaul, it is customary to replace the water pump anyway.

Figure 12-13  Align the timing marks before removing the timing belt so you’ll know how they align during reassembly.

chain or gears for excess slack or backlash. Remove the tensioner and guides if applicable. Remove the camshaft or crankshaft sprocket to release the chain or belt (Figure 12-14). You may need to use a puller to remove the crankshaft sprocket (Figure 12-15). You may be able to pry it off, but do not use a hammer; you will chip the teeth. If the engine has timing gears, remove them now. Carefully inspect the timing mechanism and sprockets to determine whether they should be reused. When performing a thorough overhaul on a high-mileage engine, you should generally replace the timing components. Record your recommendation. Engine block

Timing cover

Tension spring

Puller

Thrust pin

Camshaft sprocket

Washer

Crankshaft sprocket

Preload bolt

Figure 12-14  A thrust pin may be used to keep the camshaft from walking in the block.

Figure 12-15  Using a puller to remove the crankshaft sprocket.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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ENGINE BLOCK DISASSEMBLY Proceed methodically through the block disassembly. There are several special procedures and critical inspections to perform. Keep your eyes open and your mind on the job; pay attention to details. Be careful not to cause any damage as you disassemble the engine. The engine should still be upright. Remove the oil pan using the reverse of the tightening sequence or a diagonal pattern around the pan. Many engine stands have drain pans that rest on their frame so the engine oil will be contained. If not, place some rags underneath the engine to keep your work area safe.

Removing the Camshaft

An impact screwdriver twists the screw as you hit the end of the driver with a hammer. It works very well to remove tightly fastened, rusty, or recessed screws. A ring ridge develops at the top of the cylinder that the rings scrape and wear down. Carbon also builds up in this area to create a smallerdiameter region of the cylinder bore.

If you are working on an OHV engine, remove the valve lifters and pushrods if this has not already been done. The lifters will normally be replaced during a thorough overhaul, but you should organize the lifters and pushrods so they could be replaced in their original positions. Remove the camshaft retainer or thrust plate before removing the camshaft carefully from the block (Figure 12-16). You may need to use an impact screwdriver on countersunk Phillips head screws. Use care to remove the camshaft; banging it against the block can chip the lobes and require replacement. Set the camshaft safely aside for later examination.

Ring Ridge Removal When the engine is running, the top ring does not reach the top of the cylinder bore. It is constantly cleaning and scraping most of the cylinder wall, but at the very top it is pushing carbon up onto a ridge. Remove this ring ridge before attempting to get the pistons out. If the pistons are driven up past the ring ridge, they can easily break. Also, if new rings and bearings are installed without removing the ridge, the top ring can hit the bottom of the ring ridge and snap the land or break the ring. Either result would be disastrous after a fresh rebuild. If you can feel the ridge with your fingernail, remove it before extracting the pistons. Move the piston down toward bottom dead center, and place the ring ridge remover on top of the piston (Figure 12-17). Tighten the top bolt down to center, and tighten the tool in the cylinder. Adjust the cutting bit so that it touches the cylinder wall just below the ridge. Then rotate the nut and cutting tip up and out through the top of the cylinder. Do not take a second pass; you could remove too much material from the cylinder wall. Repeat for each of the cylinders.

Figure 12-16  After removing the thrust plate, attach some long bolts into the camshaft to give yourself leverage to pull it straight out. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Figure 12-17  Turn the ridge reamer in a clockwise direction to thread the cutters up the cylinder to remove the ridge.

Piston Removal Before removing the pistons, check the connecting rod caps for markings. They may be numbered or have punch marks on both halves of the cap. If they are not marked, use a paint stick or correction fluid to mark the rods. If you use a number punch, to keep from distorting the cap halves, mark the caps on their parting faces while they are installed. Number one is at the front (harmonic balancer) end of the engine (Figure 12-18). If the rod caps are installed on the wrong connecting rods or even backward on the same rod, the bore will not be perfectly round. This will cause crankshaft and bearing damage as the crank is forced to turn through a distorted bore. Remove one connecting rod cap. You may need to tap the rod bolts and side of the cap lightly with a brass hammer to loosen the caps. Place a piece of vacuum line over the rod bolts so that they do not scrape the crankshaft or cylinder wall as you tap the piston out ­(Figure 12-19). Use a plastic mallet to drive the piston out. You will be replacing the bearings, so it is appropriate to tap on the bearing half in the rod. Do not let the piston drop; pull it out the rest of the way once its head is out of the top of the block. Leave the bearing halves in so you keep

Figure 12-18  Mark the rod and cap with a paint stick or a number punch. The caps must be returned to the same rod and bolted in the same direction.

Figure 12-19  Protect the crankshaft and cylinder walls by using rubber hose on the ends of the connecting rod bolts.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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them with the correct connecting rod for inspection. Lightly thread the cap back on the rod, and store in a safe place where the pistons will not get scratched. Remove all the pistons.

Crankshaft Removal Line boring the main bearing bores means boring these bores so they are perfectly aligned with each other.

The main bore in which the crankshaft lies was drilled out with one long boring bar. This is called line boring. As a result of this process, the caps and the block will form round bores only if the caps are installed in the same spot and in the same direction. If a main cap is put on backward, it will cause the crank to seize (Figure 12-20). Check the main caps for markings that indicate number and direction. If there are none, use a center punch or number punches to mark the block and the caps. Loosen the main caps in two stages in the reverse of the tightening sequence. In the first stage, turn each main cap bolt about one turn to loosen it. Then follow the proper sequence again and fully loosen the bolts (Figure 12-21). The main caps have a tight fit and can be removed using two of the loose bolts (Figure 12-22). Remove the caps leaving the bearings installed for a thorough inspection. If the bearings are in their proper spots, you will be able to see if there is any pattern to the wear. You may be able to pick out something as serious as a twisted main bore or a bent crankshaft by looking at the bearings. Remove the crankshaft, and store it on end to prevent it from bending or sagging.

Core and Oil Gallery Plugs Many times you will send the engine block out to a machine shop to have it thoroughly cleaned and perhaps have the cylinders bored. Technicians in the machine shop will then remove the oil gallery plugs and clean the passages. They will also remove and replace the freeze plugs on any old or high-mileage engine. Your shop may also choose to perform these operations in-house if properly equipped. To remove core plugs, you can use a punch or chisel to hit on one side of the plugs. Be careful not to drive the plug into the block. With the plug turned out of the block, grab it with pliers or vise grips and pull it out of the block (Figure 12-23). Alternately, thread a sheet metal screw into the center of the plug. Put vise grips on the screw, and tap or pull it out with the plug attached. Be sure to lightly sand the corrosion out of the sealing surface of the bore with an emery cloth before installing new core plugs. Oil gallery plugs have tapered threads that seal very tightly. Though you would think they would be constantly lubricated with oil, the reality is that they can become quite rusty and difficult to remove. Use the proper tool to remove them; this may be a square plug, an Allen head, or an eight-point socket. If they are particularly difficult, heat them with a torch, drop a little wax on them, and try again. It may help to use an impact gun; just be sure to Main cap installed backward

Block

Figure 12-20  With the main caps on backward, the main bore is no longer round. This can cause premature bearing wear or can seize the crankshaft. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Main bearing cap bolt loosening sequence 7

1

9

4

5 3 PRY

8 10 6

2

Figure 12-21  Follow the recommended sequence for removing the main bearing cap bolts; this will prevent crankshaft warpage.

Figure 12-22  Main bearing cap removal.

Core plug

Drift Remove loose plug with pliers Drive core plug inward at bottom

Figure 12-23  Remove the core and gallery plugs so the block can be thoroughly cleaned.

apply plenty of force against the plug to prevent stripping the head. Use stiff-bristle, long gallery brushes and hot soapy water to remove all sludge and debris from the oil galleries. Blow the passages out with pressurized air to get any residual particles out and to dry the galleries. A thorough cleaning of the block and all components is an essential step in engine repair. Any residual contamination left in the engine can lead to premature failure. Proper cleaning is required during the rebuilding process (Figure 12-24). With the engine fully disassembled and the parts well organized, you will be able to inspect each of the components thoroughly. With this information, you will be able to make appropriate repair decisions. It is common to see significant damage to the cylinder bores and crankshaft, for example, and to determine during disassembly that engine replacement would offer a more efficient and cost-effective resolution (Figure 12-25). With the engine block disassembled, it should be thoroughly cleaned and inspected. Before cleaning the block, remove the core and gallery plugs. After the block is cleaned, coat it with a water-repellant solution. This is important in the cylinder and journal bores to prevent the formation of surface rust. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Crack

Figure 12-24  The block is thoroughly cleaned in a hot tank before inspection and machining.

Figure 12-25  The crack (highlighted by dye penetrant) in this racing engine will be pinned to save the block.

This chapter discusses the process of inspecting the block casting, main bearing bores, camshaft bores, cylinder bores, piston assemblies, and crankshaft. Keep a record of the needed parts and machining procedures required before reassembling the engine. Also, this chapter covers the procedures for reconditioning the components of the cylinder block assembly.

INSPECTING THE CYLINDER BLOCK

Magnafluxing is a crack detection method that can be used on any ferrous metal component. Magnets are placed at either end of the component, and liquid with metal filings is poured over the component. If there is a crack, the filings line up across the crack.

Begin block inspection by first giving it a thorough visual inspection. Inspect the bores and journals for wear patterns and the entire casting for cracks. Look for cracks especially in the cylinder walls and in the lifter valley. If an engine had a coolant consumption problem or if it was overheated, use a special procedure to check for cracks that cannot be detected visually. Cast-iron blocks can be checked by magnafluxing. To magnaflux the block, you apply magnets at either end of the casting and spread a solution on the block that contains metal filings. If there is a crack, the filings will line up on either side of it, attracted by the opposite charges across the crack. To check for a crack on an aluminum block, pour a special dye penetrant over the block. If there is a crack, the dye will settle into it and highlight the crack under a black light so you can see it. You may have to send the block out to the machine shop to have these procedures performed (Figure 12-25). Also, use this time to clean and inspect all oil passages. Some of these passages can be quite small and easily plugged (Figure 12-26). Use a small bore brush or a piece of wire to clean all oil passages. If the block passes visual inspection, it must be checked for deck warpage, cylinder wall wear, crankshaft saddle alignment, camshaft bore wear, and lifter bore wear.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Figure 12-26  Make sure that all oil passages are thoroughly cleaned.

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Figure 12-27  Measure the deck in several directions to determine the amount of warpage.

Checking for Deck Warpage Visually inspect the deck for scoring, corrosion, cracks, and nicks. If a scratch in the deck is deep enough to catch your fingernail as you run it across the surface, the deck needs to be resurfaced. Measure deck warpage using a precision straightedge and feeler gauge. To obtain correct results, the deck must be completely clean. Check for warpage across the four edges and across the center in three directions (Figure 12-27). The amount of warpage is determined by the thickest feeler gauge that will fit between the deck and the straightedge (Figure 12-28). Compare the results with specifications. The deck can be resurfaced if the cylinder block dimensions will still be within specifications after machining  (Figure 12-29). Even if the deck is within specifications, it is a good practice to put a new

The deck is the top of the engine block where the cylinder head is attached.

Classroom Manual Chapter 12, page 235

Special Tools Precision straightedge Feeler gauges

Deck

Block Deck Height

Crankshaft centerline

Figure 12-28  Clean the deck thoroughly, and then use a straightedge and feeler gauges to measure for warpage. If the deck is not flat, the head gasket will not seal.

Figure 12-29  The deck may be resurfaced if the overall block height will still be within specifications.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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surface finish on the deck so the gasket will seal properly. This can be done by using a light cut on the milling machine or using a special disc to clean the deck. If the deck is warped, it is important to determine how much material the manufacturer will allow to be removed. If more material will have to be removed than the manufacturer allows, the block will have to be replaced or a thicker head gasket will have to be used (if available). Removing more material than allowed may result in piston-to-valve contact. In addition, removing stock from the deck surfaces may affect intake manifold bolt alignment. V-type engines require both decks to be machined the same amount to keep the compression ratio equal on both sides.

Inspecting and Measuring Cylinder Wall Wear

Taper is the difference in diameter at different locations in a bore or on a journal.

Special Tools Dial bore gauge Micrometer Telescoping gauge

Caution If the cylinder is bored to accept an oversize piston, oversize rings are required. A cylinder’s out-ofroundness refers to the difference in diameter measured across the cylinder. In other words, how far from being a perfect circle, and closer to resembling an oval is it.

After visually inspecting the cylinder bores, use a dial bore gauge, an inside micrometer, or a telescoping gauge to measure the bore diameter. First, check to see if the cylinders have been bored to an oversize on a previous rebuild. Oversize pistons usually have a stamped number on the piston head to indicate the size. If the piston has no numbers, bore oversize can be checked by measuring the cylinder diameter near the bottom of the bore. Since this is a nonwear area, if the bore is larger than original specifications, the cylinder has been oversized. This information is important when ordering new pistons and rings. Common piston oversizes are 0.020, 0.030, 0.040, and 0.060 inch. Metric oversizes are in 0.50-mm increments. Piston movement in the cylinder bore produces uneven wear throughout the cylinder. The cylinder wears the most at 90 degrees to the piston pin on the thrust sides of the cylinder walls. Wear also occurs most at the top of ring travel, where combustion pressures and temperatures are hottest and there is the least lubrication. Wear decreases toward the bottom of the cylinder, resulting in taper. Taper in the cylinder bore causes the piston ring gaps to change as the piston travels in the bore. Out-of-round wear is caused by the thrust forces exerted by the piston. Another cause of out-of-round wear is gasoline washing away the oil film from the cylinder walls during cold engine operation or other high-fuel conditions. Normally, the most cylinder wear occurs at the top of the ring travel area. Pressure on the top of the ring is at a peak and lubrication at a minimum when the piston is at the top of its stroke. A ridge of unworn material will remain above the upper limit of ring travel. Below the ring travel area, wear is negligible because only the piston skirt contacts the cylinder wall. A properly reconditioned cylinder must have the correct diameter and have no taper or out-of-roundness, and the surface finish must be such that the piston rings will seat to form a seal that will control oil and minimize blowby. Taper is the difference in diameter between the bottom of the cylinder bore and the top of the bore just below the ridge (Figure 12-30). Subtracting the smaller diameter from the larger one gives the cylinder taper. Using a dial bore gauge is the easiest way to measure for taper (Figure 12-31). Set the gauge to zero near the bottom of ring travel, and drag the gauge up to the top of ring travel. The reading on the dial is the amount of taper. Repeat the procedure a few times to be sure your readings are consistent. Often, some taper is permissible. Later model, 1990s and newer, engines may specify as little as 0.002 inch (0.0508 mm), while many older engines allow up to 0.006 inch (0.1524 mm). The only way to be certain is to check the manufacturer’s specifications for the engine you are working on. If an engine has too much taper, it must be bored. Some taper is permissible, but normally not more than 0.006 inch (0.1524 mm). If the taper is less than that, reboring the cylinder is not necessary. Cylinder out-of-roundness is the difference between the cylinder’s diameter when measured parallel with the crank and then perpendicular to the crank (Figure 12-32). Often, a cylinder bore is checked for out-of-roundness with a dial bore gauge; however, a telescoping gauge can also be used (Figure 12-33).

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Cylinder bore taper

A

C Cylinder walls

Figure 12-30  To check for taper, measure the cylinder diameter at A and C. The difference between the two ­readings is the amount of taper.

Figure 12-31  A dial bore gauge makes measuring taper quick work.

Cylinder block

Cylinder bore

Figure 12-32  Measure the bore diameters on the thrust and nonthrust sides.

Figure 12-33  Measure the bore diameters just below the ring ridge. The difference between the two readings is the amount of cylinder out-of-round.

SERVICE TIP  A simple method to check taper without any special measuring tools is to use a feeler gauge and an old piston ring. Use a piston to square an old ring just below the ring ridge, and measure the end gap with feeler gauges. Push the ring down to the bottom of ring travel with the piston and again measure the ring end gap. The amount of taper is the difference between the two readings.

Measure the cylinder near the top of ring travel on the thrust sides and then on the nonthrust sides. Compare the readings on the dial of a bore gauge; the difference is outof-round. When using a telescoping gauge and micrometer, subtract the diameter of the nonthrust side from the diameter of the thrust side. This gives you the measurement of out-of-round. Look at the following example: Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Thrust Diameter Nonthrust Diameter Out-of-Round

Special Tools Precision Straightedge Arbor

Cylinder No. 1

Cylinder No. 2

Cylinder No. 3

Cylinder No. 4

3.656 in.

3.656 in.

3.656 in.

3.657 in.

–3.651 in.

–3.652 in.

–3.650 in.

–3.651 in.

0.005 in.

0.004 in.

0.006 in.

0.006 in.

The original diameter of the cylinders is 3.650 inch. Compare your measurements to the specified diameter; the engine could have been bored oversize. You would need to know this when ordering parts. This engine has cylinder out-of-round between 0.004 and 0.006 inch. On an older engine, this may be just barely acceptable. Many newer engines specify a maximum of 0.001 inch (0.0254 mm) to 0.002 inch (0.0508 mm) of out-of-round. Some newer engines allow for absolutely no out-of-round or taper, while some older engines may allow up to 0.005 inch (0.127 mm). It is important to check the specifications for the engine you are working on to make a good repair decision. If the out-of-round is beyond the allowable limit, the engine should be bored to produce a powerful and long-lasting engine. When new rings are installed in a cylinder with too much out-of-round blowby, compression loss and oil consumption can result. When an engine requires boring, new oversized pistons will have to be fitted. Given today’s trend toward replacement, these findings may dictate engine replacement rather than overhaul.

Checking Main Bearing Bore Alignment Over the life of the engine, the main bearing bores can become misaligned (Figure 12-34). The main bearings will usually compensate for this by wearing unevenly; however, if new main bearings are installed into an engine with the bores misaligned, the crankshaft will have increased resistance to turning. If excessive misalignment is not corrected, the new main bearings will fail prematurely. Upon inspection of the old main bearings, it may be possible to determine if the bores are misaligned. A warped crankcase will result in bearing wear on one side of the insert. Warpage of the main bearing bores can be checked with a precision straightedge and a feeler gauge. The straightedge must be longer than the length of the engine block. With the main bearing inserts removed, install the bearing caps and torque the bolts to specifications. This stresses the crankcase to provide accurate measurements. Place the straightedge into the bore. Then select a feeler gauge half the thickness of the maximum oil clearance. If the feeler gauge fits under the straightedge on any of

Centerline of warped crankcase

True centerline of crankcase

Figure 12-34  The crankcase can warp, causing saddle misalignment.

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Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

the saddles, the block is warped. Follow Photo Sequence 26 for the procedures on performing this measurement. Repeat this procedure at two other parallel positions in the bores. A second method is to use an arbor ground to 0.001 inch (0.025 mm) less diameter than the minimum saddle bore specification. The arbor must be long enough to fit into all bores simultaneously. Place the arbor into the saddles with the bearings removed and install the bearing caps. Torque the bolts to specifications. Attempt to rotate the arbor using a foot-long bar. If it will not turn, the crankcase is warped. Another method is to coat the crankshaft main-bearing journals with Prussian blue and install the crankshaft into the saddles. New bearings are installed for this method. With the bearing caps installed and torqued, rotate the crankshaft two revolutions. Then turn the engine upside-down and rotate the crankshaft through two additional rotations. This ensures that the weight of the crankshaft will fall on both bearing halves. Remove the crankshaft from the block, being careful to lift it straight up. The areas of contact on the bearing will be blue. Acceptable alignment is indicated when 75 percent or more of the bearing is blue. If the amount of warpage is not excessive, it can be corrected. This is done by line boring the saddles and installing the appropriate oversize bearings.

549

Special Tools Dial bore gauge Micrometer Telescoping gauge Small-bore gauge

Engine Block Bore Measurements All bores of the engine block should be measured to determine size, taper, and out-ofround. This includes the main bearing, camshaft, and lifter bores. In particular, the main bearing bores are susceptible to wear. When a main bearing becomes excessively hot, the bearing bore size decreases. Bearing bores can be checked with a telescoping gauge, an inside micrometer, or a dial bore gauge. When measuring main bearing bores, the caps must be installed and the bolts properly torqued. Check bore diameter in three directions (Figure 12-35). The vertical measurement should not be larger than any of the others. A larger reading in the vertical direction indicates that the bore is stretched. Out-of-round measurements of less than 0.001 inch (0.025 mm) are acceptable, provided the vertical reading is not the largest. If the bore measurements are out of specifications, the block will require line boring before assembly. An engine that requires line boring is a good candidate for replacement.

Figure 12-35  Measure the main bore in different locations to check for out-of-round.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 26

Typical Procedure for Checking Main Bore Alignment

P26-1  This engine uses a single piece main cap or “bedplate” to hold the crankshaft. Loosen the bedplate or the main caps to begin the check of the main bore alignment.

P26-4  Use a plastic mallet if the bearings come out hard. Keep them in order so you can look for patterns of wear that can indicate problems.

P26-2  Lift the bedplate or main caps off, and remove the crankshaft.

P26-3  The block mating surface must be clean, and the main bearings are removed.

P26-5  Torque the bedplate or main caps back on in sequence and to specification.

P26-6  Lay a machined straightedge the length of the bore, and check for any warpage. Generally, no more than 0.001 inch is allowed, but as always, check the specifications.

P26-7  Check in the center of the main bore as well.

P26-8  Flip the engine over to check the lower half of the bores. A misaligned bore can cause premature bearing wear or even a seized crankshaft.

Check the camshaft bores in the same manner. If the wear is out of limits, the bores can be honed to accept oversized bearings, if available. Visually inspect the lifter bores for scoring or wear. Clean the bores with a stiff brush to remove any varnish. Measure the diameter of the bores, and compare to specifications. If necessary, the lifter bores can be honed to a standard oversize to fit oversize lifters if available. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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551

INSPECTING THE CRANKSHAFT As the pistons are forced downward on the power stroke, pressure is applied to a crankshaft, causing it to rotate. The crankshaft transmits this torque to the drive train and ultimately to the drive wheels. These pressures and rotational forces eventually cause wear and stress on the crankshaft. The lack of proper lubrication or the addition of abrasives greatly accelerates this wear. Before the crankshaft can be reused, a thorough inspection of suspect areas is required. These areas include main-bearing journals, connecting-rod journals, fillets, thrust surfaces, oil passages, counterweights, seal surfaces, flange, and vibration dampener journal. Generally, crankshaft inspection begins with a thorough visual inspection, followed by checking for warpage and measuring the journals for excessive wear. An additional check is to inspect for stress cracks. This can be done again visually, using the tap test as is done on brake drums. The tap test is done by tapping the counterweights with a steel hammer while hanging the crankshaft, listening for a ringing. A crack could be indicated by a dull “thud” sound (Figure 12-36). If the crankshaft is cracked it must be replaced. First, visually inspect the crankshaft for obvious wear and damage. This includes inspecting the threads at the front of the crankshaft, the keyways, and the pilot bushing bore. When inspecting the journals, run your fingernail across their surfaces to feel for nicks and scratches. If a journal is scored, it will have to be polished before accurate micrometer readings can be obtained. Remember to inspect the area around the fillet very closely. Stress cracks can develop in this area (Figure 12-37). If the crankshaft is going to be used under extreme conditions, or if there are any doubts concerning cracks, magnaflux the crankshaft. Clean the oil passages by running a length of wire or a small bore brush through them, followed by spray cleaner (such as spray carburetor cleaner). Inspect the passage openings. There cannot be any nicks in these areas. If there is a rise in the metal around the hole, it will have to be removed by polishing or grinding the journal.

Checking Crankshaft Warpage The loads placed on the crankshaft can cause it to warp into a bow shape. If a warped crankshaft is installed with new bearings, the bearings will fail prematurely. Always check crankshaft straightness before returning it to service. If the crankshaft is out of specifications, it should be replaced; however, some machine shops use a special press to straighten the crankshaft.

The pilot bushings or pilot bearings are pressed into the centerline of the crankshaft at the back. They are used to support the front of the transmission’s input shaft. Polishing is the process of removing light roughness from the journals by using a fine emery cloth. Polishing can be used to remove minor scoring of the journals that does not require grinding.

Figure 12-36  Despite severe damage to the journals under the hoop, this $1,400 racing crank will be repaired if it is not cracked. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 12-37  This scored crank should be polished, if not ground or replaced. If reused, it should be checked carefully for cracks in the fillets and probably magnafluxed.

The total movement of the dial indicator (above and below zero) is the total indicator reading (TIR).

To check crankshaft warpage, place the crankshaft into two V-blocks or between lathe pins so that they support the end main-bearing journals (Figure 12-38). Install a dial indicator on the middle main-bearing journal with the plunger positioned in the three o’clock position on the journal. Rotate the crankshaft one revolution while observing the dial indicator. The amount of crankshaft warpage is 50 percent of the total indicator reading (TIR) (Figure 12-39). Remember, any journal out-of-round will affect the TIR. If specifications are not available, a general rule is that TIR should not exceed half of the minimum bearing clearance specification. SERVICE TIP  A crack can sometimes be detected by “ringing” the counterweights with a light tap from a hammer. A dull sound indicates a crack is present.

SERVICE TIP  Excessive torsional vibrations usually result in a crack near the number 1 piston connecting-rod journal. Causes of excess vibration include an unbalanced crankshaft, a defective vibration damper, a wrong flywheel, a damaged or improper converter drive plate, or an improperly balanced torque converter.

Dial indicator

Rotate crankshaft two complete revolutions

V-blocks

Figure 12-38  A setup to check crankshaft warpage.

Figure 12-39  The actual amount of warpage is half of the total indicated reading.

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553

Record the indicator readings, and mark the high spots on the journal. The highest of the runout readings indicates the point of the bend. Marking the points of highest runout on each journal provides a general plane of the bend. All of the marks will usually line up. If they do not, this indicates multiple bends in the shaft. While the crankshaft is set up in the V-blocks, move the dial indicator to measure the runout of the vibration dampener journal. Next, measure the runout of the flywheel flange. Compare these results to specifications.

Measuring Crankshaft Journals Main- and connecting-rod journals are machined to very close tolerances and require thorough inspection. Use an outside micrometer to measure the diameter, taper, and out-of-round of each journal (Figure 12-40). Measure each journal at two or three locations and in two different directions (90 degrees apart) at each location (Figure 12-41). Compare the measurements with specifications. If any of the main-bearing journals are out of specifications, all main-bearing journals should be ground to the next undersize. This ensures that the journals are on the same centerline. Another alternative is to build up the crankshaft journal using special welding techniques, and then grind the journal to its original size.

SERVICE TIP  If V-blocks are not available, it is possible to measure the crankshaft warpage by installing the front and rear upper bearing inserts and then placing the crankshaft into the block. Set a dial indicator to measure the middle journal. This procedure will be accurate only if the crankshaft saddles are straight.

Special Tools V-blocks Dial indicator

The lateral movement of the crankshaft is controlled by a thrust bearing and a thrust surface on the crankshaft (Figure 12-42). Inspect the thrust surface for indications of excessive contact and wear. If the thrust surface is worn, causing excessive end play, the crankshaft will have to be replaced, the surface built up, or an undercut radius machined into the journal (Figure 12-43).

Crankshaft journals may be called crank pins.

Figure 12-40  Measure the crankshaft journals to be sure the crank is within specifications and can be reused.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Journal diameter

Thrust surface

Journal width

Figure 12-41  Measuring the journals for wear, taper, and out-of-round.

Figure 12-42  Crankshaft thrust is controlled by a thrust bearing and a thrust surface on the crankshaft.

Original radius New undercut radius

Figure 12-43  Undercut radius restores the thrust surface.

INSPECTING THE HARMONIC BALANCER AND FLYWHEEL Classroom Manual Chapter 12, page 245

The harmonic balancer (vibration dampener) is inspected for signs of wear in its center bore. Also inspect the rubber mounting for indications of twisting and deterioration. Replace any harmonic balancer that has slipped. If the flexplate or flywheel is to be reused, inspect it closely for stress or heat cracks. Flexplates generally crack around the mounting hole area. Flywheels can develop cracks as a result of overheating because of a slipping clutch. If the cracks are deep or the flywheel is excessively blue, replace the flywheel. SERVICE TIP  If the crankshaft journals have pits, yet measure within specifications, polish the worst journal. After the journal is clean of pits, remeasure it. If it is still within specifications, the crankshaft will not require grinding.

Flywheels with light scoring and surface check cracks can be resurfaced (Figure 12-44). In addition, warpage can be removed during the resurfacing procedure. The clutch disc must have a flat surface to ride against. If the flywheel is warped, the contact surface for the disc is reduced, causing it to chatter on engagement or slip. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 12-44  This milling machine can be used to resurface cylinder heads, block decks, or flywheels.

Flywheels and flexplates also contain the starter ring gear. Inspect the gear for damage. If a flexplate ring gear is damaged, replace the flexplate. Most flywheel ring gears can be removed from the flywheel, and a new one can be installed.

SERVICING THE CYLINDER BLOCK ASSEMBLY The cylinder block assembly may require some machining operations to ensure proper sealing and performance. Although not all machining operations listed in this section will have to be performed on all engine block assemblies, it is important for today’s technician to be aware of the machining options available. This section discusses the procedures for performing some of the most popular methods of reconditioning the engine block, crankshaft, connecting rods, and pistons. If you are working in a general repair facility, you will have many of these processes performed at a machine shop. It is not the intent of this text to replace the operating manuals for the equipment being used. The procedures performed in this manual are general procedures and are designed to familiarize you with the procedures. Always refer to the equipment manufacturer’s instructions and the engine service manual for proper machining procedures.

Special Tools Micrometer

Line Boring and Align Honing The main bearing bores can be resized and realigned by line boring or align honing. Line boring is performed if the bearing bores are warped or are excessively worn, while align honing is used to make small corrections to the bores. The main purposes of these operations are to be sure that all bores are straight, have the correct diameter, provide the correct bearing crush, and provide proper heat transfer. Line boring or align honing the main bearing bores is usually the first machining operation performed on the engine block since many of the other operations require the main bearing bores to be lined and sized. Line boring and align honing resize and realign the main bearing bores by slightly changing their location in the crankcase. The first procedure to be performed when reconditioning the main bearing bores is to remove metal from the parting surface of the bearing cap. After the proper amount of metal is removed from the main bearing caps, these caps are installed on the engine block, and the retaining bolts are tightened to the specified torque. A line hone (Figure 12-45) or a line boring machine is then used to bore the main bearing bores so they are properly aligned. The main bearing bores are usually bored to their original diameter. Align ­honing or line boring main bearing bores is normally done in an automotive machine shop, not in an automotive repair shop.

Caution Do not store a crankshaft lying down. In this position, it may warp or become bent. Store the crankshaft in a support designed for the crankshaft.

Special Tools Line boring machine Dial bore gauge Align honing is used to make small corrections to the bores.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 12-45  Set the honing mandrel so the centering pins are resting on the center saddle.

Resurfacing the Deck

Special Tools Line boring machine Dial bore gauge

Resurfacing the deck gives the cylinder head gasket a flat, machined surface to seal against. Even if the deck is not warped, a finish surface should be cut. A minimum amount of material should be removed to provide a new surface finish for proper gasket sealing. This operation is usually performed after the main bearing bores are machined and before cylinder boring. This is because many boring bars and indexing plates are mounted to the deck surface. The exception is if the cylinders are being sleeved. In this case, the sleeves are installed first and then the deck is surfaced. Generally, three methods are used to recondition the deck surface of the engine block: grinding, broaching, and milling. The same milling machine shown in Figure 12-44 can be used to resurface cylinder decks. Resurfacing the block deck is usually done in an automotive machine shop, not in an automotive repair shop.

Cylinder Reconditioning

Cylinder boring makes it possible to bore cylinders to accept oversize pistons.

Classroom Manual Chapter 12, page 239

Special Tools Boring bar Dial bore gauge Indexing plate Torque plate

The cylinder must be the proper diameter for the piston, be free of taper, and have no out-of-round. In addition, the surface finish must allow the rings to seal. Depending on the amount of wear, cylinder wall reconditioning can be performed using one of the following methods: ■■ Deglazing ■■ Cylinder boring ■■ Honing ■■ Sleeving the cylinder Before reconditioning the cylinder bores, use an abrasive wheel to cut a chamfer at the top of the cylinder. Make sure the angle of the chamfer does not cut into the area of upper ring travel. The finished cylinder wall surface should have a crosshatch pattern. It is the proper crosshatch that assists in sealing the piston rings. The crosshatch leaves thousands of small diamond-shaped reservoirs for oil and maintains the oil film for the rings to glide on. After the cylinders are reconditioned, they must be thoroughly cleaned. Use hot soapy water and a stiff brush to remove all of the residue. Rinse and dry the block; then lightly coat each cylinder with engine oil. Do not use a solvent tank or steam cleaner to clean the cylinders. You must get into each bore and remove all traces of grit and metal particles. If any grit or metal shavings are left in the bores, the rings will be damaged. Deglazing.  If the original crosshatch is still visible, clean the varnish using lacquer thinner. Achieving the surface finish required by today’s engines is impossible using the old methods of glaze breaking. If the crosshatch is not present, hone the cylinder with a rigid hone.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Cylinder Boring.  If it is determined that the cylinders are worn beyond specifications, it may be possible to bore the cylinders to accept oversize pistons. This operation is possible only if the cylinder bore diameter is not beyond the maximum allowed. If the bore is too large, the cylinder wall is thinner than required to maintain its shape and to prevent cracks. Whenever a cylinder is bored, the pistons will have to be replaced with the correct oversize. If any of the cylinders require boring, all of the cylinders should be bored to the same oversize to keep cylinder output equal. Use the inspection notes to determine the oversize of the bores required to clean up the worst cylinder. Refer to the parts supplier’s catalog and engine service manual to determine available oversize pistons. The cylinders should be bored to the smallest oversize piston that will clean the worst cylinder bore. All cylinders will be bored to this oversize. It is a good practice to match the pistons to the bore. The pistons will have some differences in size due to manufacturing tolerances. Measure the exact size of each of the replacement pistons. Then determine the desired finished size of the cylinder and how much will be bored, leaving 0.003 to 0.005 inch (0.075 to 0.125 mm) for finishing by honing. When setting up the boring machine, there are some special considerations. First, centering the cutting bit is vital. Center is not based on the center of the original bore. Instead, the bit must be centered to the crankshaft centerline. One method of centering the bit is to use an indexing plate attached to the deck of the block (Figure 12-46). The indexing plate aligns the cutting bit to bore the cylinders based on the position of the head bolts. This method is used by many high-performance machine shops. Another method is to center the cutting bit using the bottom of the cylinder where no wear has occurred. Once the boring bar is located at the centering location, turn the control knob to expand the centering fingers. The bar may have three or four fingers. The fingers contact the indexing plate or cylinder wall and are pushed out tightly. With the bar centered, clamp the machine to the engine block by inserting an anchor assembly through the cylinder adjacent to the one being bored. Next, raise the boring bar out of the cylinder. Another consideration is that the boring machine must be square to the engine block. If the machine is not square, the cylinders will not be parallel. Also, keep the cutting bit dressed and lapped.

Boring bar

557

Blueprinting is a technique of building an engine using stricter tolerances than those used by most manufacturers. This results in a smoother running, longer lasting, and higher-output engine.

Indexing plate

Cylinder block

Figure 12-46  An indexing plate is used to center the boring bar. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Install the cutting bit into the tool holder using a micrometer that has been set to the desired dimension of the cylinder. Fit the tool holder into the boring bar head, and adjust it to the required setting using a special boring bar micrometer. The set screw locks the tool holder into the head.

Caution The boring bar relies upon the deck surface to align its cutting bits. The deck surface must be machined with at least a zero cut before the cylinders are bored.

SERVICE TIP  Make a small cut above the ring ridge first. Measure the cut to determine if the boring bar cutter is properly set. If an improper cut is made in this area, it will not affect piston travel.

Caution Some engine blocks have a thin block design that requires the use of a torque plate when honing the cylinder. Always refer to the manufacturer’s service manual for information regarding special considerations.

Special Tools Driver motor Rigid hone Torque plate Dial bore gauge

Before cutting the bore, set the feed stop to prevent the boring bit from going past the bottom of the cylinder. Finally, set the spindle speed and feed rate. The settings used will depend upon the type of machine used, the type of material the block is constructed of, and the type of bit used. The boring machine manufacturer provides guidelines to use in determining speed and feed rate. Finally, turn on the motor and engage the feed lever. The cutting bit will work its way down the cylinder as it cuts the bore. When the bore bar reaches the bottom of its travel, turn off the motor. Remove or relocate the cutting bit so the bore bar can be raised out of the cylinder without damaging the new cylinder wall surface. Some machines use a long cutting bit for cutting a chamfer at the top of the cylinder. If a chamfer was not already cut, do so now. Check the bottoms of the cylinders for chamfer. Some chamfer should remain. A sharp edge at the bottom of the cylinder can scrape oil off of the piston skirt. Honing Cylinder Walls.  A rigid hone can be used to correct slight taper or out-of-round conditions in the cylinder. Honing is also recommended to bring the cylinder bore to its final size after boring. This is done to remove the very rough surface the boring bar leaves (Figure 12-47).

Figure 12-47  Notice the torque plates bolted to the deck to prevent the honing process from distorting the cylinders. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

559

Cylinder honing can be performed using manual or automatic feed machines. Follow Photo Sequence 27 for general cylinder honing operations using a manual honing machine. When honing a cylinder to size, set the stop so the stones are stroked just above the deck. Do not allow the stone to come out of the top of the cylinder, or a taper will be cut. If a manual machine is used, stroke the honing head with a fast and steady up-anddown movement to achieve the correct crosshatch pattern. On either system, allow the stone to run free of drag after the bore has been honed to its desired size. This results in desirable plateaus that act as bearing surfaces for the rings. SERVICE TIP  Obtain the replacement pistons before honing the cylinder walls. Measure each piston, and custom hone each cylinder to size. There are some variations in sizes of pistons within a set.

After cylinders are honed, they must be thoroughly cleaned. Use hot soapy water and a stiff nonmetallic brush to remove all of the residue. Rinse and dry the block; then lightly coat each cylinder with engine oil. PHOTO SEQUENCE 27

Typical Procedure for Cylinder Honing

P27-1  Tools required to perform this task include a variety of hone stones, a torque plate, a new head gasket, bolts to attach the torque plate, a honing machine, a setting gauge, and a bore gauge.

P27-2  Install and torque the main bearing caps to the crankcase. This stresses the lower end of the engine block.

P27-3  Place a new head gasket on the block deck, and install the torque plate. Make sure the bolts used to attach the plate go the same distance into the block as the original cylinder head bolts.

P27-6  Select the appropriate stone to rough cut the cylinder to within 0.0005 inch of the finished size. A stone grit of 150 to 220 is ­usually used.

P27-4  Install the engine block into the honing machine and level it.

P27-5  Locate the setting gauge in the cylinder to be bored and center it. Once it is centered, tighten the knob, and move the graduated slide to zero. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 27 (CONTINUED)

P27-7  Place one of the stones on the setting gauge, and add shims to remove any slack. A stone that is properly shimmed will slide in and out of the setting gauge easily. Both stones are shimmed using the same thickness.

P27-10  With the stones fully retracted, insert the honing head into the cylinder. Adjust the cradle so the stones protrude about 3 8 inch out from the top of the cylinder.

P27-8  Place one of the guides in the setting gauge to determine the size of the shim required. Select the second guide shim in the same manner.

P27-11  Select the proper stroke length, ­spindle speed, and stroking rate.

P27-14  Engage the clutch to begin the stroking of the hone head. P27-13  Turn on the motor, and adjust the coolant flow over the work.

P27-9  Install the stones into positions 1 and 2 of the honing head. The main guide goes into position 3, and the centering guide into ­position 4.

P27-12  Use the feed wheel to expand the stones gradually. The stones should be just snug in the cylinder.

P27-15  Hone for about 20 to 30 ­seconds; then ­disengage the clutch and measure the bore. Once the bore diameter is within 0.0005 inch of the desired finished diameter, change stones to provide a finer cut. The finish stone used will depend upon the type of piston rings selected.

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Figure 12-48  The plateaus provide a bearing-type surface for the rings to glide over.

Plateau Honing.  Plateau honing removes the peaks left by normal honing operations (Figure 12-48). With the peaks flattened out, the rings will seal and wear in faster. You will need to vary the machine settings to match the specific bore diameter you are working with. Set the spindle speed and strokes per minute to achieve a crosshatch angle between 30 and 40 degrees. Start with a 200- or 220-grit stone. Hone the cylinder to within 0.0005 inch (0.013 mm) of the finished size. Change to a 280-grit stone, and leave the machine’s spindle speed, stroke rate, and feed the same as when finished with the previous stone. Use this stone to bring the cylinder bore to its final size. Leaving the machine at the same settings, install a plateau honing tool, soft honing tool, or 600-grit stone. Run the machine for about 45 seconds to remove the peaks. You should always consult the service information for your particular engine, as the surface finish requirements can vary. Different types of rings will also require different stone grits. Many machinists use the Automotive Engine Rebuilders Association (AERA) publications to locate up-to-date engine machining specifications that are not easily found in traditional service information sources. Sleeving.  Even engine blocks that are not equipped with sleeves may be repaired using a dry sleeve. This is usually done if one or two of the cylinders are worn or damaged to the extent that boring cannot be done, or when the expense of boring the cylinders is too high. Sleeving also provides a method of repairing a cylinder that is cracked. Dry sleeves are typically installed as an alternative to boring all the cylinders and installing oversize pistons when a low-mileage engine has suffered a catastrophic failure in one or two cylinders. The other cylinders would need to have very little wear, or boring all the cylinders would make the most sense. An example of a situation when installing a dry sleeve would be advisable is if an engine with 34,000 miles on it had a connecting rod come loose and it severely scored just that cylinder. To install one sleeve on the low-mileage engine would be much less expensive than boring all the cylinders and purchasing new oversize pistons. Most sleeving operations are performed using dry sleeves that are pressed into the block with a 0.001- to 0.002-inch (0.025- to 0.050-mm) interference. A general rule of thumb is 0.0005-inch (0.013-mm) interference per inch (25.4 mm) of cylinder bore diameter. Dry sleeves are available in 3 32 - or 1 8 -inch (2.5- or 3.0-mm) wall thickness. The cylinder is sleeved by boring it to a size 0.002 inch (0.050 mm) less than the outside diameter of the sleeve. If any finer adjustment is required to the cylinder, use a hone. The sleeve may not be perfectly round. Measure it in three directions at the top and bottom; then add the six measurements together. Divide the sum of the measurements by 6 to get the average outside diameter (Figure 12-49). Generally, a 3 32 -inch (2.5-mm) sleeve requires the cylinder wall to be bored about 0.1875 inch (4.8 mm) over the standard size. For the 1 8 -inch (3-mm) sleeve, the cylinder will need to be bored about 0.250 inch (6.5 mm) over standard. When the cylinder is bored, leave a step about 0.250 inch (6.5 mm) from the bottom to prevent the sleeve from pushing out (Figure 12-50). Chamfer the top of the cylinder to assist in sleeve installation. In addition, cut a chamfer at the bottom of the sleeve. Coat the sleeve with a high-pressure lubricant; then drive it into the cylinder. Cut off any excess sleeve with a hacksaw or cutoff bit. After all sleeves are installed into the block, machine the deck to blend the top of the sleeve with the deck. Since pressing the sleeves into the block distorts the cylinders, install all sleeves before honing any of the bores. If only some of the cylinders are to be sleeved, install the sleeves before machining any of the other cylinders. The inside diameter of the sleeve is smaller

Automatic honing machines allow the operator to set the required crosshatch pattern. In addition, some can be used to bore the cylinders to the next oversize instead of using a boring bar. This is the recommended procedure for reconditioning aluminum cylinders.

Sleeving is the process of boring the cylinder to accept a sleeve. Sleeving is used to restore the cylinder bore to its original size.

If sleeves are to be installed, perform this operation before resurfacing the block deck. Note that the amount to be bored is over standard, not the amount to be removed from the existing cylinder bore size. Classroom Manual Chapter 12, page 238

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Driver

Cylinder sleeve A

Sleeve

Engine block

A A

A A

A

A A

Figure 12-49  Determining the outside diameter of the new sleeve.

Special Tools Boring bar Dial bore gauge Torque plate Sleeve driver Rigid hone

Figure 12-50  A step is left at the bottom of the bore so the sleeve cannot drop into the crankcase.

than a standard bore. After all the sleeves are installed, they can be bored and honed to the desired size using the methods already discussed. Match the piston to the cylinder to achieve the best results. CUSTOMER CARE  It is in the best interest of the customer to do a little research to make sure that high-quality rings are fitted into cylinders with the correct surface finish. Opting for the cheapest and easiest option may not provide the level or length of performance that she expects.

A dry sleeve can be installed into a cylinder block by pressing it in. In this design there is no air gap and no coolant passage between the sleeve and the block.

Sleeve Installation Many aluminum and some cast-iron blocks use replaceable liners in their cylinders (Figure 12-51). Dry sleeves are thin-walled liners that are pressed into the block, while wet sleeves are thicker and are held in place by supporting flanges in the block. Each type of sleeve is serviced differently. In addition, dry sleeves can be used to restore worn cylinders.

Figure 12-51  Some engine blocks have replaceable sleeves. Liners can also be used to correct excessive wear problems in a cylinder. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Top measurements – 4.1378 4.1365 4.1362 Bottom measurements – 4.1381 4.1379 4.1378

Measure in three directions.

Average outside diameter 4.1378 + 4.1365 + 4.1362 + 4.1381 + 4.1379 + 4.1378 24.8243

4.1374 6 24.8243 Measure in three directions.

Figure 12-52  The sleeve is driven into the cylinder bore with an interference fit. A cut-down axle works well as a driver.

SERVICE TIP  Thermal heating the block to about 2008F (938C) and freezing the sleeve before pressing the sleeve will make installation easier.

Replacing Dry Sleeves.  Dry sleeves are pressed into the block with 0.001- to 0.002-inch (0.025- to 0.050-mm) interference. To remove the sleeve, it is bored to make its walls very thin. The thin shell is then pried away from the block and lifted out. The new sleeve is installed by lubricating the outer diameter with a high-pressure lubricant and then pressing it or driving it into the block (Figure 12-52). The sleeve is longer than the cylinder, requiring the remainder of the sleeve to be cut off using a hacksaw or a cutoff bit. The deck is machined after the sleeves are installed to blend the top of the sleeve with the deck. The sleeve bore diameter is smaller than a standard bore, so it must be bored and honed to original size. Replacing Wet Sleeves.  Many engines originally fitted with wet sleeves call for replacement of any sleeves that have any scoring, taper, or out-of-round. Wet sleeves are supported in the block only at the top and bottom of the cylinder. Engine coolant surrounds the sleeve and is kept out of the crankcase by O-rings. To remove wet sleeves, the supporting flanges in the block are bored out. A special puller may be required to remove the sleeve (Figure 12-53). The puller is fitted inside the sleeve and then expanded so it is tight against the walls. Some pullers use a slide hammer attachment to force the sleeve out.

Wet sleeves are thicker sleeves constructed to support the forces of combustion; coolant jackets surround them.

Lifter Bore Repair To complete the machining of a pushrod (OHV) engine block, the lifter bores are reconditioned. The lifters must be able to rotate in the bores. If they cannot, the bottom of the lifter will wear along with the camshaft lobe.

0.250 in.

Figure 12-53  A special sleeve puller. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Use a small glaze breaker or hone to remove any burrs or glazing inside the bore. Be careful not to enlarge the bore; only clean it up. If the bore is too large, oil will leak past the lifters and accelerate wear. It is also possible to remove varnish from the lifter bore with a small brush and lacquer thinner. If the bores are excessively damaged, some manufacturers and aftermarket suppliers provide oversize lifters.

Special Tools Small glaze breaker or hone

CAMSHAFT AND BALANCE SHAFT BEARING SERVICE Camshaft Bearing Measurement, Removal, and Replacement Worn camshaft bearings cause low oil pressure. During an engine rebuild, the camshaft bearings are usually replaced. To determine the camshaft bearing clearance, measure the camshaft bearing diameter with an inside micrometer or a telescoping gauge, and measure the matching camshaft journal with a micrometer. Subtract the two readings to obtain the bearing clearance. If the bearing clearance is more than specified, the camshaft bearings must be replaced. A special camshaft bearing removal and replacement tool is used to remove and replace the camshaft bearings. This tool consists of a guide cone (1), driving w ­ ashers (2 or 3), expander bearing drivers (4–8), driver bars (9 or 10), expander jaws (11), expander sleeve (12), expander cone (13), expander shaft (14), and expander assembly (15) (Figure 12-54). The expansion plug in the rear camshaft bearing bore located in the rear of the block must be removed before camshaft bearing removal and replacement. Use the proper expander/driver, driver bar, and a hammer to remove the front and rear camshaft bearings (Figure 12-55). Some engine manufacturers recommend the use of a special puller to remove all the camshaft bearings. Always follow the instructions in the vehicle manufacturer’s service manual. Use the proper driver bar, expander/driver, and expander cone to remove the center camshaft bearing (Figure 12-56). The centering cone centers the driver so the camshaft bearing is driven straight out of the bore. SERVICE TIP  If the block has oil grooves around the camshaft bearing bores, install the camshaft bearings with the oil hole in the bearing at the three o’clock position. This position allows oil to enter the bearing easily as the camshaft rotates.

Be sure the camshaft bearing bores are clean and smooth prior to installing the camshaft bearings. In some engine blocks, the camshaft bearings are different sizes, with the largest bearing at the front of the block and the bearings progressively smaller toward the

10

15

9

12

11

14

13

3

8

7

6

5

4

2

Figure 12-54  Camshaft bearing puller and driver with attachments.

1

Figure 12-55  Removing or replacing front or rear camshaft bearings.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Figure 12-56  Removing or replacing a center camshaft bearing.

rear of the block. Be sure to install the camshaft bearings in the proper bores. Use the proper driving tools and centering cone to install the center camshaft bearing. Be sure that the oil hole in the bearing is aligned with the oil passage in the block on all the camshaft bearings. If these oil holes are not aligned, the camshaft bearing does not receive adequate lubrication, and the bearing will fail very quickly. When the bearing fails because of lack of lubrication, the camshaft journal will be severely scored, and so the camshaft must be replaced. Install the front and rear camshaft bearings with the proper driving tools. Some front camshaft bearings are installed past the front surface of the bearing bore to provide oil flow from this bearing bore to the timing chain and gears.

Balance Shaft Bearing Measurement, Removal, and Replacement Use a C-clamp to mount a dial indicator above the rear of the balance shaft ­(Figure 12-57). Position the dial indicator stem against the balance shaft, and zero the dial indicator. Grasp the balance shaft, and pull upward and push downward on this shaft while observing the shaft to rear bearing play. If this play exceeds specifications, the balance shaft bearing and balance shaft must be replaced. After the balance shaft is removed, measure the balance shaft journal diameter with a micrometer to determine if this journal is worn. Use the C-clamp to mount the dial indicator near the front of the balance shaft, and position the dial indicator stem against the surface of the balance shaft. Zero the dial indicator. Grasp the balance shaft, and pull upward and push downward on the balance shaft while observing the shaft Dial indicator

Figure 12-57  Measuring rear radial balance shaft play. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Dial indicator

Figure 12-58  Measuring balance shaft end play.

to block play on the dial indicator. If this play is excessive, the balance shaft requires replacement because the balance shaft journal directly contacts the block bore. After the balance shaft is removed, measure the front block bore to determine if the block bore is worn. Since there is no load on the balance shaft, wear in the front balance shaft block bore is unlikely. Use a C-clamp to mount the dial indicator on the front of the block so the dial indicator stem may be positioned against the retaining bolt in the front of the balance shaft (Figure 12-58). Grasp the balance shaft, and move it forward and rearward while observing the end play on the dial indicator. If the end play is excessive, the balance shaft retainer may be worn. Position the dial indicator such that the stem is contacting one of the balance shaft gear teeth, and zero the dial indicator (Figure 12-59). Grasp the balance shaft, and try to turn it back and forth while observing the gear lash on the dial indicator. If the gear lash is excessive, the balance shaft drive and driven gears must be replaced. Use a special puller to remove the balance shaft (Figure 12-60).

SERVICE TIP  The camshaft bearings should require moderate force to drive them into the bearing bores. If the bearings can be installed easily, the bearing may have the wrong outside diameter.

Dial indicator

Balance shaft gear

Figure 12-59  Measuring balance shaft gear lash.

Figure 12-60  Removing the balance shaft.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Figure 12-61  Removing the rear balance shaft bearing.

Figure 12-62  Installing the rear balance shaft bearing.

Figure 12-63  Installing the balance shaft.

Use the special removal tool to remove the rear balance shaft bearing (Figure 12-61). Be sure that the rear balance shaft bearing bore is clean and smooth. A special bearing installation tool is used to install the rear balance shaft bushing (Figure 12-62). Use the proper driving tool to install the balance shaft (Figure 12-63). When installing the balance shaft drive and driven gears, these gears must be properly timed, or severe engine vibrations will occur.

RECONDITIONING CRANKSHAFTS A worn crankshaft does not always require replacement, though it is often the more costeffective option. Depending on the severity of the damage and the material the crankshaft is constructed from, it may be reconditioned with no adverse affects. As discussed in the Classroom Manual, crankshafts are constructed from forged steel or cast iron. Forged steel crankshafts are easily repaired. Until recently, cast crankshafts were too brittle to be reconditioned, other than resizing the bearing journals. Modern materials have made cast crankshaft reconditioning possible, including straightening. Proper interpretation of the crankshaft inspection results will provide the necessary information regarding the extent of crankshaft reconditioning required. The journal surfaces can be reconditioned to provide a smooth surface, and if necessary, they can be built up using a special welding process and then machined to restore original size. In addition, many crankshafts can be straightened; however, do not attempt repairs on a cracked crankshaft (Figure 12-64). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 12-64  Despite this severe damage, this specially made racing crankshaft will be repaired.

When reconditioning the crankshaft, a proper order should be followed. First, if the crankshaft is warped, it must be straightened before any other machining operations are performed. Second, if the bearing journals are tapered, out-of-round, or worn, they may be ground to accept a standard undersize bearing. After the journals are ground to the desired size, they should be polished. If the journals are not worn beyond specifications, they should be polished to provide a smooth surface.

Crankshaft Straightening WARNING  Always wear approved eye protection when performing this task.

Hydraulic pressure is used to assist in relieving pressure, not to straighten the shaft.

If the inspection of the crankshaft indicates excessive warpage, the shaft may be straightened. The labor costs of this operation must be balanced against the replacement cost. If the crankshaft is to be straightened, this procedure must be done before any other machining operations are performed. There are two methods for straightening the crankshaft: peening and using straightening presses. Both methods work on forged and cast shafts; however, pressing cast shafts requires extra caution. In addition, it is important to understand exactly what the operation of crankshaft straightening is. Straightening the crankshaft is done by relieving the stress tension built up in the shaft. The shaft is not bent back into alignment. Removing the stress within the crankshaft will automatically return it to its original shape. Stress is removed by striking the crankshaft in the direction of the bend. A hammer and a rounded bronze chisel with its end dressed to fit the fillet radius of the rod journals are used for peening (Figure 12-65). Striking the journal in this location prevents damage to the bearing surface. The chisel is struck with a hard, sharp blow from the hammer. The crankshaft straightening press applies hydraulic pressure to the bend. A dial indicator is attached to the journal to indicate the amount of overbend being applied. At this time, the chisel and hammer are used to strike the fillet radius of the bent journal in the direction of the bend. This is done to relieve stress in the shaft.

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Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

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Area of bend

0.004 in. (0.100 mm)

0.011 in.

(0.280 mm)

0.002 in.

(0.050 mm)

0.007 in.

0.006 in.

(0.180 mm)

(0.150 mm)

TIR readings

Figure 12-65  Peening a crankshaft to remove warpage.

Figure 12-66  The journal with the greatest amount of TIR is the location point of the bend. Start at this location, and move outward to remove the bend.

With either procedure, the crankshaft is placed into V-blocks to support the ends at the rear seal diameter and dampener mounting surface. Following is the procedure for peening the crankshaft. All straightening is done at the rod journals, not the main journals. Once the TIR and location of the bend are identified and the crankshaft is properly supported, position it so the high point of runout (the marks) is facing down. Straighten the shaft starting at the journal indicating the greatest amount of TIR. Work from this journal down the shaft in both directions to remove the warpage (Figure 12-66). Locate V-blocks or clamps on the main-bearing journals adjacent to the actual bend location. Frequently check the progress of the work to prevent bending the crankshaft in the opposite direction.

Peening is the process of removing stress in a metal by striking it in the direction of the bend.

Special Tools V-blocks Dial indicator Bronze chisel

Journal Grinding The importance of journal surface condition to forming the correct oil barrier between the journal and the bearing was discussed in the Classroom Manual. The manufacturer often applies a hardening treatment to the journals to protect them from wear; however, even with hardened surfaces, the bearing journals can become scored or scuffed due to improper lubrication, excessive heat, contamination, or improper installation. It may be possible to restore the journal surfaces by grinding them to a standard undersize. Grinding of the crankshaft journals is done to correct any of the following conditions: ■■ Out-of-round ■■ Taper ■■ Improper oil clearances ■■ Scratches, scoring, or nicks ■■ Damaged thrust surfaces The crankshaft shown in Figure 12-37 has scoring deep enough that it should be reground or replaced.

INSTALLING OIL GALLERY PLUGS AND CORE PLUGS After thorough cleaning, install the oil gallery plugs. Make sure that the threads in the block and on the plug are clean. Apply pipe sealant to the threads, and torque the plugs in to their specification. Check to be sure that each gallery hole is properly sealed. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Sealing edge before installation

Cup-type plug

Cup-type core plug replacer tool

Figure 12-67  Use a proper tool to install core plugs so you don’t damage them.

New oil gallery plug

New core plug

Figure 12-68  With new core plugs and oil gallery plugs installed, the block is clean and ready for reassembly.

SERVICE TIP  If the shaft has multiple bends, treat the shaft as if it were separate shafts and remove each bend individually.

Caution Do not attempt to straighten a crankshaft by striking it against the direction of the bend. Doing this causes the shaft to be bent back into position and weakens the shaft.

Make sure that there are no deposits or corrosion in the core plug bores. Any dirt in the bores or on the new plugs can cause leakage. Apply a hardening sealant as specified to the outside diameter of the core plug. Use a core plug tool or bearing driver to install the core plugs (Figure 12-67). The driving face should be just slightly smaller than the edges of the plug. Do not hit the core plug in the center area; this will collapse it and distort the sealing edge. Using a punch to tap the plug in will also deform the core plug and cause leaks (Figure 12-68).

CASE STUDY Inspection of a V8 engine block indicated that one cylinder was excessively scuffed and damaged. The technician researched the options available and discussed them with the customer. It was decided that the cost of a new block was not feasible and having to bore each cylinder would require the purchase of new pistons. In this instance, it was decided that the most cost-effective method of repairing the block was the installation of a sleeve. After completing all the required machining operations on the engine block, the technician was ready to turn her attention to the crankshaft. The inspection notes taken indicated that one of the mainbearing journals required grinding to restore its surface finish. All other main-bearing journals were good. Realizing it is unusual to have only one bearing fail in this manner, the technician inspected the old bearing very closely and discovered that the original bearing was undersize even though the journal was not ground. Someone had attempted to remove an engine noise by simply installing a thicker bearing to take up clearance. The extra friction caused the journal to score. To maintain proper crankshaft position in the block, all main-bearing journals were ground to the next standard undersize, new bearings were installed, and oil clearances were checked. By taking the time to find what is in the best interest of the customer, your reputation as an honest technician will grow.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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ASE-STYLE REVIEW QUESTIONS 1. Technician A says to reverse the tightening sequence when loosening the cylinder head. Technician B says to loosen the main caps starting at the front of the engine and moving toward the rear. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that you can pry most ­harmonic balancers off with two big pry bars. Technician B says that you can damage the ­crankshaft if you do not protect the threads while using a puller. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 3. Technician A says to rotate the engine to TDC number 1 before removing the timing mechanism. Technician B says to make a mental or written note of the location of the timing marks. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 4. Technician A says that the pistons should come out the top of the block. Technician B says to drive on the edge of the ­piston skirt with a punch to remove the pistons. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 5. The crankshaft has been removed for inspection. Technician A says the area around the fillet is a common location for stress cracks. Technician B says a crack near the number 1 ­piston connecting-rod journal may indicate a faulty vibration damper. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. The cylinder block is ready for inspection. Technician A says that deck warpage can be checked using a precision straightedge and feeler gauge. Technician B says that the main bearing saddle alignment can be checked with a precision straightedge and a feeler gauge. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 7. While servicing camshaft bearings: A. The largest bearing is installed at the rear of the block. B. Worn camshaft bearings may cause a ­knocking noise at idle speed. C. A hammer and brass punch may be used to remove camshaft bearings. D. Worn camshaft bearings cause low oil pressure. 8. While measuring and servicing balance shaft bearings: A. A Balance shaft end play may be measured with plastigage. B. Balance shaft gear lash may be measured with a dial indicator. C. Balance shaft upward and downward movement may be measured with a machinist’s ruler. D. Balance shaft bushings may be replaced with a slide hammer-type puller. 9. Technician A says that the cylinder boring bar is ­centered to the crankshaft centerline. Technician B says that an indexing plate can be used to center the boring bar. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Cylinder bore inspection is being discussed. Technician A says that the greatest amount of wear will be toward the bottom of the ring travel area. Technician B says that if any of the cylinders are out of specifications, all cylinders should be bored to a standard oversize. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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ASE CHALLENGE QUESTIONS 1. If pistons are removed without removing the ring ridge, the following may result: A. The piston skirt may be damaged. B. The piston pin may be broken. C. The connecting rod bearings may be damaged. D. The piston ring lands may be broken. 2. While discussing cylinder measurement, Technician A says that cylinder taper is the difference between the cylinder diameter at the top of the ring travel and the cylinder diameter at the center of the ring travel. Technician B says that cylinder out-of-round is the difference between the axial cylinder diameter at the top of the ring travel and the thrust cylinder diameter at the bottom of the ring travel. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

4. Technician A says to mark the main caps before disassembly. Technician B says that if main caps are installed in the wrong direction, the crankshaft could seize. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says that a failed harmonic balancer can cause a crankshaft to crack. Technician B says that a cracked crankshaft is generally welded to repair it. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

3. Technician A says that core plugs are generally replaced during a high-mileage overhaul. Technician B says that oil galleries should be blown out with an air gun to clean them. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

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Name ______________________________________

Date __________________

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JOB SHEET

74

DISASSEMBLING AN ENGINE BLOCK Upon completion of this job sheet, you should be able to properly disassemble the bottom end of the engine (also known as the short block). NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: C.2. Disassemble engine block; clean and prepare components for inspection and reassembly. Tools and Materials • Technician’s tool set • Rubber hose • Number punch or paint stick Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific engine. Write down the information, and then perform the following tasks: 1. Locate the service information for engine disassembly, and read through the instruction.

h

2. Draw a diagram of the head bolt loosening sequence.

3. Set the engine at TDC number 1 firing, and note the markings on the camshaft if you are working on an OHC engine. Remove the cylinder heads, and label all components and bolts as needed.

h

4. Is your engine an OHV or OHC engine? _________________________________________________________________________ 5. What sort of timing mechanism is used? _________________________________________________________________________ 6. Remove the timing cover, and observe the timing marks. Describe the marks and their positions. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Task Completed 7. Remove the timing chain, belt, or gears. Carefully inspect the chain, belt, or gears; the sprockets; the guides; and the tensioners. List below the condition of each of the components and whether they should be reused or replaced: ______________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Feel for a ring ridge with your fingernail in each of the cylinders. Which cylinders have a noticeable ridge? _________________________________________________________________________ Use the ring ridge remover to remove the ridge before removing the pistons.

h

9. Are the connecting rod caps marked? _________________________________________________________________________ If not, use a paint stick or a number punch to mark them. Then loosen the connecting rod nuts for one cylinder, place pieces of rubber hose over the rod bolts, and drive the piston out of the top of the engine using the plastic or wooden end of the hammer on the rod. Be sure to put the rod cap back on the piston assembly. Repeat for all pistons. 10. Locate the main cap loosening sequence, and draw it.

11. Loosen the main caps in the proper sequence. Loosen each bolt one turn; then repeat the sequence to fully loosen the bolts. Set the caps aside, and remove the crankshaft.

h

12. Visually inspect the crankshaft for scoring or cracks; describe your results. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

13. Visually inspect the block assembly for cracks, severe wear, and core and oil gallery plug condition. Describe your results. _________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 14. Based on your initial inspections, what is your recommendation for further measurement and possible repair of the block assembly? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

575

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Name ______________________________________

Date __________________

577

JOB SHEET

75

ENGINE BLOCK CRACK DETECTION Upon completion of this job sheet, you should be able to properly check a cylinder block for cracks. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: C.3.  Inspect engine block for visible cracks, passage condition, core and gallery plug condition, and surface warpage; determine necessary action. Tools and Materials • Service manual • Technician’s tool set • Magnetic particle inspection equipment • Penetrant dye crack detection equipment Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure for Iron Engine Blocks

Task Completed

Using an assigned engine and the proper service manual, you will identify and perform the required steps to detect cracks on an iron engine block. 1. Check technical service bulletins for articles related to engine crack detection. Describe what you found. _________________________________________________________________________ 2. After cleaning the cylinder block, place the electromagnet in one area of the cylinder block gasket surface.

h

3. Turn the electromagnet on, and dust the iron powder in between the magnets.

h

4. If a surface or near-surface crack is present, the powder will collect near the crack. Did this occur? _________________________________________________________________________ 5. Continue to perform this testing on the remainder of the cylinder block, paying special attention to cylinders, crankshaft saddles, core and gallery plugs, and oil/coolant passages. Describe what the results of this test were. _________________________________________________________________________ _________________________________________________________________________ Procedure for Aluminum Engine Blocks Using an assigned engine and the proper service manual, you will identify and perform the required steps to detect cracks on an aluminum engine block. 1. Check technical service bulletins for articles related to engine crack detection. Describe what you found. _________________________________________________________________________ 2. After cleaning the cylinder head using conventional methods, spray the suspected area with the supplied spray bottle of special cleaner and wipe it dry.

h

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Task Completed 3. After the cleaner dries, spray the area with the penetrant and wait 5 minutes.

h

4. After the penetrant dries, spray the area with the developer and wait 5 minutes.

h

5. If a surface or near-surface crack is present, the developer will outline the crack in a different color. Use of a black light will aid in seeing any cracks. Did this occur? _________________________________________________________________________ 6. Continue to perform this testing on the remainder of the cylinder block, paying special attention to cylinders, crankshaft saddles, core and gallery plugs, and oil/coolant passages. Describe what the results of this test were. _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Name ______________________________________

Date __________________

579

JOB SHEET

76

MEASURING DECK WARPAGE Upon completion of this job sheet, you should be able to properly inspect and measure the engine block deck for warpage. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: C.3. Inspect engine block for visible cracks, passage condition, core and gallery plug condition, and surface warpage; determine necessary action. Tools and Materials • Straightedge • Feeler gauge • Disassembled engine block • Gasket scraper • Gasket remover spray Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Using the engine you have disassembled and the proper service manual, you will identify and perform the required steps to inspect and measure the engine block deck for warpage. 1. Specification for maximum warpage allowed. __________________________________ 2. What are the special tools required to perform this procedure? _________________________________________________________________________ _________________________________________________________________________ 3. Make sure the deck surface is clean. If it looks like there is any gasket material left, spray the gasket remover and scrap the remaining material off. Do not use a steel scraper on aluminum blocks.

h

4. Note any damage (nicks, scratches, etc.) to the deck surface. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Actual warpage measurement. Left bank _______________ Right bank _______________

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6. Based on your findings, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Name ______________________________________

Date __________________

581

JOB SHEET

77

CYLINDER BLOCK THREAD CLEANING Upon completion of this job sheet, you should be able to clean the block threads with a tap and die set. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.7. Perform common fastener and thread repair, to include: remove broken bolt, restore internal and external threads, and repair internal threads with thread insert. This job sheet addresses the following MLR task for Engine Repair: A.6. Perform common fastener and thread repair, to include: remove broken bolt, restore internal and external threads, and repair internal threads with thread insert. Tools and Materials • Technician’s tool set • Tap and die set • Thread repair kit Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________

Task Completed

Procedure Using the engine block from the engine you have disassembled and the proper service ­manual, you will identify and clean the threads listed below with a tap and die set. 1. Gather the engine thread repair kit and the tap and die set. Describe the thread size and pitch for the following components: Fastener

Thread Diameter

Thread Pitch

1. Cylinder head bolt threads in block 2. Oil pan bolt threads in block 3. Timing cover bolt threads in block 4. Main bearing cap bolt threads in block 5. Main bearing cap bolts 6. Connecting rod bolt threads 7. Connecting rod nuts 8. Cylinder head bolts 9. Rocker arm stud/shaft

2. Clean the threads listed above by using the proper thread file, tap and/or die, and an air blow gun. Make sure to blow the dirt and metal filings out before and after you clean up the threads.

h

3. Are any of the threads damaged beyond repair? _________________________________

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4. If yes, what repair method are you going to have to do to restore them? _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Name ______________________________________

Date __________________

INSPECTING AND MEASURING THE CYLINDER WALLS Upon completion of this job sheet, you should be able to properly inspect and measure the cylinder walls for wear. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: C.4. Inspect and measure cylinder walls/sleeves for damage, wear, and ridges; determine necessary action. Tools and Materials • Technician’s tool set • Dial bore gauge • Engine block • Cylinder deglazing equipment • Cylinder cleaning equipment and soap Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Using the block from the engine you have disassembled and the proper service manual, you will identify and perform the required steps to inspect and measure the cylinder walls for wear. 1. Do any of the cylinders have visible signs of wear or damage?   h Yes  h No If Yes, which one(s)? _________________________________________________________________________ _________________________________________________________________________ 2. Is the cross-cut pattern still visible on all cylinder walls?   h Yes  h No If No, on which ones is it no longer visible? _________________________________________________________________________ _________________________________________________________________________ 3. What is the specification for the bore? _________________________________________ 4. At what location in the cylinder is the bore measurement to be taken? _________________________________________________________________________ 5. What is the specification for the maximum amount of taper? _____________________ 6. At what locations in the cylinder is the taper measured? _________________________________________________________________________ 7. What is the specification for the maximum amount of out-of-round?_______________ _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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JOB SHEET

78

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Chapter 12

Task Completed 8. At what location in the cylinder is out-of-round measured? _________________________________________________________________________ 9. Measure each cylinder at the locations required, and record your results. Bore

Taper

Out-of-Round

Cylinder 1

_______________

_______________

_______________

Cylinder 2

_______________

_______________

_______________

Cylinder 3

_______________

_______________

_______________

Cylinder 4

_______________

_______________

_______________

Cylinder 5

_______________

_______________

_______________

Cylinder 6

_______________

_______________

_______________

Cylinder 7

_______________

_______________

_______________

Cylinder 8

_______________

_______________

_______________

10. Put an * (or more than one if necessary) in the preceding chart to indicate any readings that are out-of-specification. 11. Have the cylinders been bored to an oversize?

h

h Yes  h No

If Yes, what size? __________________________________________________________ 12. Prepare the engine for cylinder deglazing. What special tools and equipment are needed for this service? _________________________________________________________________________ 13. Deglaze the cylinders to the point where you can see the crosshatch as specified in the service manual.

h

14. After deglazing the cylinders, thoroughly wash them out with soap. Make sure to air dry everything.

h

15. Soak a clean towel with engine oil, and apply it to the cylinder walls to prevent flash rusting.

h

16. Based on your readings, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Inspecting, Disassembling, and Servicing the Cylinder Block Assembly

Name ______________________________________

Date __________________

INSPECTING AND MEASURING MAIN BEARING BORE ALIGNMENT Upon completion of this job sheet, you should be able to properly inspect and measure the main bore alignment and determine if there is a connecting rod alignment problem. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: C.9.  Identify piston and bearing wear patterns that indicate connecting rod alignment and main bearing bore problems; determine necessary action. Tools and Materials • Straightedge • Feeler gauge • Engine block Describe the vehicle being worked on: Year_____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure Using the block from the engine you have disassembled and the proper service manual, you will identify and perform the required steps to inspect and measure the main bores for proper alignment. 1. Do any of the main bearings show signs of wear caused by bore misalignment? h Yes  h No If Yes, which one(s)? _________________________________________________________________________ _________________________________________________________________________ 2. Do any of the saddles or caps have visible signs of wear or damage? h Yes  h No If Yes, which one(s)? _________________________________________________________________________ _________________________________________________________________________ 3. What is the maximum amount of bore misalignment allowed? ____________________ 4. Describe the method used to determine bore misalignment. _________________________________________________________________________ _________________________________________________________________________ 5. Actual amount of bore misalignment. _________________________________________ 6. Visually inspect the connecting rod bearing and piston wear patterns. Do they correlate to the main saddle wear patterns and directions? ________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

585

JOB SHEET

79

586

Chapter 12

7. Based on your findings, what is your recommendation? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 13

SHORT BLOCK COMPONENT SERVICE AND ENGINE ASSEMBLY

Upon completion and review of this chapter, you should understand and be able to describe: ■■ ■■

■■ ■■

■■ ■■

How to inspect main and rod bearings and perform accurate failure analysis. How to visually inspect and measure pistons and determine necessary repairs. How to inspect piston pins and ­determine condition. How to perform a complete inspection of the connecting rods, including ­big-end and small-end bores and bends and twists. How to recondition connecting rods. How to install press-fit and full-floating piston pins.

■■

■■ ■■ ■■ ■■ ■■

How to properly install piston rings, including measuring and correcting ring end gap, checking side clearance, and staggering end gaps. How to properly install camshaft ­bearings and camshaft into an OHV engine. How to correctly install the crankshaft and measure end play. How to install main and rod bearings and measure bearing oil clearances. How to correctly install the piston assemblies into the engine block. How to properly complete the engine assembly.

Basic Tools Basic mechanic’s tool set Service manual

Terms To Know Big end Camshaft end play Dry starts Head Land Lugging

Minor thrust side Oversized bearings Pickup tubes Pin boss Pressure plate Registering

Sizing point Skirt Small end Undersized bearings

INTRODUCTION With the engine block disassembled, cleaned, and repaired, it is now time to inspect the internal components. The engine bearings, pistons, rings, and connecting rods must all be carefully inspected. You will reassemble the engine using new rings and bearings and any other components that have significant wear. Proper reassembly of the engine block includes several critical measurements: ring end gap and side clearance, bearing oil clearances, camshaft and crankshaft end play, and rod side clearance when applicable. Proper torque sequences and specifications are essential for professional work.

Classroom Manual Chapter 13, page 250

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588

Chapter 13

INSPECTING CRANKSHAFT BEARINGS

Oversized bearings are thicker than standard to increase the outside diameter of the bearing to fit an oversized bearing bore. The inside diameter (ID) is the same as standard bearings. Undersized bearings have the same outside diameter as standard bearings, but the bearing material is thicker to fit an undersized crankshaft journal.

As discussed in the Classroom Manual, the crankshaft does not rotate directly on the main or rod bearings. Instead, it rides on a thin film of oil trapped between the bearing and the crankshaft. If the journals are worn or become out-of-round, tapered, or scored, the oil film will not form properly. This will result in direct contact with the bearing and eventual damage to the bearing, crankshaft, or both. Soft materials are used to construct the bearings in an attempt to limit crankshaft wear. Crankshaft bearings are always softer than the metal structure they support. When an engine is reconditioned, the main and rod bearings are replaced. However, inspection of the old bearings provides clues to the cause of an engine failure; for example, the soft material used to construct the bearings allows impurities to embed into it. Excessive metal flakes may alert the technician that there was metal-to-metal contact between moving parts within the engine. Inspect the main and rod bearings for wear patterns, and record your determination in your notebook or on the work order. Note any unusual wear patterns indicating crankcase or crankshaft misalignment, lack of oil, and so forth. Inspection of the back side of the bearing may indicate that previous machining was performed to the crankshaft or main bearing bores. Most bearings are stamped to indicate standard, oversize, or undersize (Figure 13-1).

Bearing Failure Analysis Bearing failure can result from a variety of causes. The most common are oil contamination, oil breakdown, or lack of oil. Other causes include improper installation, improper crush, and worn or bent components. Normal bearing wear is usually indicated by a smooth, gray appearance. Any wear should be confined to the center of the bearing insert, with little wear located by the parting surface. Under normal conditions, the outer material can wear away and expose some of the inner layers. Dirt intrusion is identified by fine scoring on the bearing surface (Figure 13-2). The most likely cause for dirt intrusion is a dirty air filter that has not been replaced during regular maintenance intervals, a loose oil dipstick, a loose oil filler cap, or overextended oil change intervals.

XXXX X

Figure 13-1  Bearing sizes are stamped on the back of the insert.

Figure 13-2  The bearings on the left are worn down to the copper under layer. The one on the right shows moderate scoring.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Metal particles cause wide grooves to be dug into the bearing surface. Small amounts of the particles are usually embedded in the bearing. Excessive metal particles indicate parts failure. If the bearing failed due to metal particles, carefully inspect the oil pump since it will usually be damaged also. Another common cause for bearing failure is loading. Bearings are under low-load conditions when the engine is operated within its effective rpm range. This range is usually 200 rpm to 400 rpm above maximum torque output, and 200 rpm to 400 rpm below the maximum horsepower output. Normal loads in the effective rpm range come from combustion pressure, centrifugal force from the piston assembly, and inertia of the piston assembly. These loads are actually a continuous series of loadings. The lower main bearing and the upper connecting rod bearing inserts carry most of the load (Figure 13-3). Excessive wear on the lower main bearings indicates the engine lugging, excessive idling, or preignition. Overloading indicated by wear on both insert halves indicates excessive engine speeds. When the loading and friction become excessive, the bearing can spin in its bore. This will destroy the crankshaft and the bore (Figure 13-4). A bearing that has spun in its bore will be loose in its cap. Both the inner and outer sides of the bearing will be scored. You will be able to see scoring in the bore as well. This requires repair to the bore; do not attempt to simply install a new bearing if the old one has spun. A repeat failure is almost inevitable. This fault with the block could also make replacement an effective alternative to overhaul. Also make sure that the oil supply holes in the block and crankshaft are clear. Oil starvation is a common cause of spun bearings. Severely worn bearings will usually damage the crankshaft journals; inspect them carefully. The specific bearings that indicate wear will also provide hints that point to the cause of the initial failure; for example, if the bearing the farthest from the oil pump has more wear than the other main bearings, this may indicate dry starts. Another example is if all of the lower main bearing inserts, except the front one, show wear and the front bearing shows wear on the upper half; the cause may be an excessively tight accessory drive belt.

Dry starts refer to an engine increasing its speed and load right after it has been started, before the oil has been properly pressurized and circulated.

Combustion force

Figure 13-3  Combustion forces will cause the lower main bearing and the upper rod bearing inserts to wear more than the other bearing half inserts.

589

Figure 13-4  The bearing spun in its bore and destroyed the crankshaft and the ­connecting rod.

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Chapter 13

CUSTOMER CARE  Dry starts are very hard on engine components. If bearing wear indicates dry starts, inform the customer of the need to allow the engine to run long enough to achieve oil pressure and circulation before it is loaded.

When inspecting the bearings, look closely at the wear pattern. Asymmetric wear patterns can provide information concerning a variety of engine problems. If the bearing appears to have localized smears, this may indicate contamination between the bearing and the saddle (Figure 13-5). The contamination deformed the bearing to the point where it contacted the journal during its rotation. This type of wear can also indicate improper assembly. Main bearing wear in different locations on all bearings indicates that the saddles are warped (Figure 13-6). A bearing cap that is not properly aligned to the saddle is indicated by excessive wear on the edges of the bearing shell. Connecting rod bearings displaying wear patterns on opposite sides of the upper and lower bearings indicate the possibility of a bent connecting rod. A shifted bearing cap is indicated by wear patterns on the parting edges. Lack of lubrication will cause the bearing to smear. Corrosion from acid formation in the oil will cause a pitted surface in the bearing. Corrosion is an indication of improper maintenance schedules, the use of the wrong type of oil, or a contamination of the oil by another fluid such as coolant or fuel.

Bearing face

Bearing back

Foreign particle

Journal

Bearing

Figure 13-5  Foreign particles under the bearing cause localized areas of wear.

The greatest amount of wear occurs on the middle bearings.

Figure 13-6  Main bearing wear indicating warped main bearing saddles.

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Short Block Component Service and Engine Assembly

591

Figure 13-7  This thrust bearing is not badly worn, but the ­bearings are always replaced during an engine overhaul.

It is also important to inspect the back of the bearing for wear. If the bearing spun in the saddle, the back of the bearing will have scoring or may look polished. If this is the indication, the bearing did not have the proper clearance between the shell and the journal. It is always important to check the manufacturer’s technical service bulletins (TSBs) for information on diagnosing abnormal bearing wear that may be common to that engine or may help you after rebuilding the engine. The thrust bearing will also show signs of wear through normal use (Figure 13-7). An excessively worn thrust bearing can cause damage to the crankshaft and block. Check the areas on the crank and block where the thrust bearing rides. If you can see wear in these areas, repairs will be necessary. Thrust bearing failure can be caused by a defective clutch pressure plate, harsh shifting, or riding the clutch when the engine is coupled to a manual transmission. On an engine mated to an automatic transmission, fluid pressure in the torque converter normally pushes the crank toward the front of the engine. If the pressure is excessive, the torque converter can swell or balloon under loads and damage the thrust bearing. Check the clutch pressure plate transmission fluid pressure, or discuss driving habits with the customer if you find excessive thrust bearing wear on an otherwise sound engine.

The pressure plate couples and uncouples the clutch disc from the flywheel on a manual transmission to transmit engine torque to the transmission.

Classroom Manual Chapter 13, page 252

INSPECTING THE PISTONS AND CONNECTING RODS The piston assembly is subject to severe temperature changes, extreme pressures, and very high inertia loads. Over the life of the engine, these forces may cause the piston to deform and become unserviceable. In addition, as the cylinder bore size increases (due to wear), the piston may be allowed to rock within the cylinder and cause skirt scuffing as it contacts the wall. Many of the pistons from modern engines do not have a skirt that protrudes downward on the piston as much as those used in past engines. This lighter weight design leads to more piston rocking when the engine is at colder temperatures (often known as the engine noise “piston slap”). Although some cylinders are made of a hardened material, this may cause excessive wear in the cylinder. Before the piston is reused, it must be inspected and measured to ensure its serviceability. The areas of concern are the head, the pin boss, the lands, the ring grooves, and the skirt. If the piston has not been cleaned already, use a scraper to remove the carbon from the top of the piston. Do not dig into the piston head; remove only the heavy deposits. Remove the remainder of the carbon by soaking the piston in a cold tank.

Caution Using a wire wheel to remove carbon from the top of the piston may result in the removal of some metal and rounding off of the piston head. Do not use a wire wheel to clean the skirt or ring grooves.

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Special Tools Ring expander Ring groove cleaner Torch tip cleaner

Caution If a bead blaster is used to clean the piston, it must be separated from the connecting rod first to facilitate cleaning and prevent connecting rod bearing damage. Piston pins connect the piston to the connecting rod. Three basic designs are used: piston pin anchored to the piston and floating in the connecting rod, piston pin anchored to the connecting rod and floating in the piston, and piston pin fullfloating in the piston and connecting rod.

Piston Ring Removal and Groove Cleaning WARNING  The rings can have sharp edges. Be very careful when removing the rings from the piston. The piston rings will most likely have a lot of carbon buildup on them, adding to the difficulty of removing them. Clean this area with a solvent as much as possible before attempting removal. Note the direction and placement of the rings as you remove them. In addition, rings are very brittle and can break easily. The edges of the break can be sharp and can easily cause injury.

The piston rings must be removed to inspect and clean the grooves. The carbon at the back of the groove must be removed to allow the new rings to compress as they are worked into the cylinder. The rings must be removed in a manner that will not damage the lands. Begin by cleaning the piston in a cold tank to remove any sludge or carbon that may inhibit ring removal. The rings can usually be removed by hand by spreading the ring gap and working the ring over the land. A ring expander can be used to remove piston rings if needed (Figure 13-8). After the rings are removed, clean the piston grooves using a ring groove cleaner (Figure 13-9). Select the proper size bit for the groove; then locate the tool over the piston with the bit in the groove. Adjust the depth of the bit to the same depth as the groove. Work the tool around the piston while checking your work carefully. Be careful not to remove any metal from the groove. Use a torch tip cleaner to remove carbon and debris from the oil drain holes of the bottom groove.

Checking Piston Pin Wear To check for any piston pin wear, clamp the connecting rod in a vise with a shop rag around it. Pull up and push down firmly on the piston. There should be absolutely no detectable movement between the rod and the piston. If there is, disassemble the piston, pin, and connecting rod to repair the problem (Figure 13-10).

Removing the Piston Pin Before removing the piston from the connecting rod, determine if the piston is offset on the rod. This is generally detectable if the piston head has a notch or arrow indicating the direction of installation (Figure 13-11). The procedure for removing the piston from the connecting rod differs between full-floating and press-fit piston pins.

Piston ring

Ring expander

Figure 13-8  Use a ring expander to remove the ring from the piston.

Figure 13-9  Use a ring groove cleaner to remove carbon from the engine.

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Short Block Component Service and Engine Assembly

593

Figure 13-10  Checking for movement between the rod and the piston.

Connecting rod Retainer ring Piston

Right and left bank indicator R

Front mark

EX

Toward exhaust

Figure 13-11  A notch or arrow on the piston head indicates which side faces the front of the engine.

Figure 13-12  Full-floating piston pins can usually be pushed out after removing the snap rings.

Full-Floating Pin Removal.  Full-floating piston pins use snap rings or locks to hold the pin in the piston pin boss. The clearance between the piston and the pin, and the pin and the small end of the rod is enough to allow the pin to be removed without the use of a press. Remove the snap rings from the pin boss, and push the pin out of the piston and the connecting rod (Figure 13-12). Note the direction the snap rings came out of the boss. Some are tapered or chamfered and must be reinstalled the same way to prevent the pin from coming loose. If the piston pin is too tight to allow removal by hand, use a brass drift and light hammer blows. Carefully inspect the snap ring groove, and replace any piston exhibiting wear or damage in this area. Press-Fit Pin Removal.  Most press-fit piston pins have an interference fit in the ­connecting rod and float in the piston. The interference fit necessitates the use of a press and special adapters to remove the pin (Figure 13-13). The special adapters prevent piston distortion and rod cocking. The lower adapter must support the piston and allow enough room for the pin to fit through it as it is pressed out. The pin driver must sit fully on the pin without contacting the piston. Once the rod is removed from the piston, store it by hanging it.

Piston offset is used to provide more ­effective ­downward force onto the ­crankshaft by ­increasing the ­leverage applied to the crankshaft.

Special Tools Press Pin drivers Piston support adapters

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Chapter 13

A

Piston pin driver Embossed mark facing up

Caution Do not reuse piston pin snap rings or locks. Reused snap rings or locks may come loose during engine operation, resulting in piston and cylinder wall damage.

Caution Do not use a hammer and drift punch to drive out the piston pin. Use special adapters to ­prevent damage to the piston. Classroom Manual Chapter 13, page 258

Figure 13-13  Special tools must be used to remove press-fit pins to prevent damage to the piston.

Piston Inspection The head of the ­piston is the top piston surface.

A piston land is the area between the ring grooves.

The piston skirt is the area from the lowest ring to the bottom of the piston.

The head of the piston is subjected to the greatest amount of heat and pressure. Visually inspect the head for any damage. Light pitting or nicks on the top of the piston generally do not necessitate replacement; however, the causes of this damage must be determined and corrected. Visually inspect the land and groove area for nicks and cracks. Damage in this area usually necessitates piston replacement. When inspecting the ring grooves, look for a step on the lower, inner portion of the groove (Figure 13-14). Combustion pressures force the ring down and outward (Figure 13-15). This movement may cause a step to wear in the groove and increase the ring side clearance. Worn grooves are reason to discard the piston. Visually inspect the skirt for indications of scuffing (Figure 13-16). Normal skirt wear is a slightly polished symmetrical pattern. Light scoring does not necessitate piston replacement; however, if the skirt is heavily scored or scuffed, the piston must be replaced

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Short Block Component Service and Engine Assembly

595

Compression pressures

Worn area High step

Figure 13-14  Check for ring groove wear.

Figure 13-15  Compression pressures work to seal the ring tighter.

Diagonal wear pattern

Figure 13-16  This piston has some moderate vertical scuffing on the major thrust side.

Figure 13-17  Diagonal scuffing due to a ­misaligned connecting rod. The piston cannot travel a true path in the cylinder.

and the cause must be identified. Scuffing in a diagonal direction on the skirt indicates a misaligned connecting rod (Figure 13-17). Finally, inspect the pin boss area for indications of cracks. This is a common area for stress cracks.

The pin boss area is a common area for stress cracks.

Classroom Manual Chapter 13, page 258

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Special Tools Rod vise Dial bore gauge The sizing point is the location the manufacturer uses to measure the diameter of the piston to determine clearance.

Measuring the Piston.  If the piston passes visual inspection, follow the manufacturer’s recommended procedures for measuring the piston. Measure the piston to determine clearance and to check for collapsed skirts. The clearance depends on piston materials and engine applications; thus, there are no general specifications. Piston clearance is determined by measuring the size of the piston skirt at the manufacturer’s sizing point. This measurement is subtracted from the size of the cylinder bore. If the piston clearance is not within specifications, it may be necessary to bore the cylinder to accept an oversize piston. Since most pistons are cam ground, it is important to measure the piston diameter at the specified location (Figure 13-18). Some manufacturers require measurements across the thrust surface of the skirt at the centerline of the piston pin. Others require measuring a specified distance from the bottom of the oil ring groove. Always refer to the appropriate service manual for the engine you are servicing. In addition, some manufacturers may require piston measurements at several locations (Figure 13-19). A piston that has smaller-than-specified diameters should be replaced. A smaller-than-specified skirt diameter may indicate a collapsed skirt. A common cause of collapsed skirts is piston pin seizure. The seized pin prevents the piston skirt from conforming properly to the bore. 12 mm (1/2 in.)

Figure 13-18  Measure the piston diameter at the specified location. 98.704 to 98.831 mm (3.886 to 3.891 in.)

98.577 to 98.704 mm (3.881 to 3.886 in.)

26.543 mm (1.045 in.)

62.230 mm (2.45 in.) Diameter D should be 0.0000 to 0.0152 mm (0.0000 to 0.0006 in.) larger than C

Elliptical shape of the piston skirt should be 0.254 to 0.304 mm (0.010 to 0.012 in.) less than diameter A than across the thrust faces at diameter B

C

C D

D A

B

45°

B

A

Figure 13-19  It may be necessary to measure the piston at several locations to determine wear or damage. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Some pistons are designed with tapered skirts. The bottom of the skirt may be 0.001 to 0.0015 inch (0.03 to 0.04 mm) larger than the top of the skirt. As the piston moves up and down in the cylinder, it is constantly changing speeds. This action can hammer hard on the piston pin and pin boss. Before reusing the ­piston, measure the pin boss bore for size and out-of-round. Then compare the results with specifications. Some machine shops will hone a worn bore to accept a larger piston pin. A dial bore gauge is the easiest to use for making these measurements. Measure the outside diameter (OD) of the piston pin, and zero the gauge to this size. Insert the gauge into the pin bore, and note the dial reading as the gauge is rotated and worked up and down the bore (Figure 13-20). As a final check, measure the ring groove for wear. This can be done by installing a new ring backward in the groove and using a feeler gauge to measure the clearance (Figure 13-21). Check the groove at several locations around the piston. If the side clearance is excessive, replace the piston. Excessive side clearance can result in ring breakage. The top ring groove generally wears more than the others. Normal ring-to-groove side clearance is between 0.002 and 0.004 inch (0.05 and 0.10 mm). With a new ring located in the groove, attempt to slide in a feeler gauge the size of the maximum clearance specification. If the gauge slides in, the clearance is excessive. Groove depth can also be checked using the new ring. Locate the ring into the ring groove in the same manner as checking clearance. Roll the ring around the entire groove while observing for binding. The ring depth should be consistent. Piston Wear Analysis.  The wear indicated on the piston can be a help in detecting the cause of the failure. Rarely does the piston cause a failure; usually something else causes the piston to fail. Studies indicate that about 41 percent of piston failures are attributable to contamination or lack of oil. The second leading cause of piston failure is scuffing. About 26 percent of piston failure is attributable to this condition. Scuffing can be caused by cylinder bores warping due to overheating, bent connecting rods, or momentary welding of the piston to the cylinder wall at top dead center (TDC). In addition, scuffing on only one side of the piston may indicate excessive idling or engine lugging.

Caution Make sure the proper rings are used when measuring clearance. While making the measurement, ensure that the ­piston ring is installed right side up. Usually there is a marking that indicates the top side of the ring. Do not fault the piston until proper ring size is verified. Improper rings may have excessive groove clearance.

Lugging of the engine results from improper gear selection for the load and acceleration or overloading the engine, such as towing in excess of the recommended limit.

Feeler gauge

Ring

Figure 13-20  Measure the piston pin boss for wear.

597

Figure 13-21  Measuring the ring groove clearance.

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Incorrect installation accounts for about 11 percent of all piston failures. Use the ­following chart to help analyze piston wear: Condition

Cause

 urned piston top. Identified by 1. B a smooth hole in the top of the piston or on the outer edge of the crown (Figure 13-22)

Abnormal combustion (detonation and preignition)

2. Jagged hole in piston head

Coolant ingestion into the combustion chamber The rapid cooling of the head as the coolant enters causes the head to crack and create a hole Valve contact with top of piston

3. Nicks on piston head

Valve contact with piston Foreign material in the intake manifold

4. Broken second land

Detonation Too thin a piston ring

5. Skirt scuffing near pin boss

Piston pin seized in bore

6. Collapsed piston skirt

Piston pin seized in bore

7. Erosion around pin boss

Broken piston pin lock ring causing piston to move on the pin and contact the cylinder wall

8. H  eavy scuffing of the skirt (scuffing on only one or two pistons)

Improper piston clearance Bent connecting rod

9. H  eavy scuffing on most pistons (Figure 13-23)

Lack of lubrication Contaminated oil Oil breakdown Piston overheating Cylinder bore distortion caused by overheating or improper head bolt torques Bent connecting rods

Figure 13-22  This piston has been badly damaged by detonation.

Figure 13-23  This piston shows severe scuffing.

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Inspecting the Piston Rings A visual inspection is usually all that is required for the rings. Visually inspect the old rings for breakage, scoring, scuffing, and glazing. The major cause for ring wear is abrasion. When inspecting the rings for wear, look for the following conditions: Condition

Cause

1. T op ring indicates more wear than the second ring and has vertical lines

Dirty air entering through the air intake system

2. Lower rings and cylinder walls show more wear than the top ring

Abrasives in the lubrication system

3. The bottom side of the ring indicates wear, leaving a lip on the outside edge

Abrasives

4. Abrasive wear (dull gray appearance with vertical lines)

Oil contamination Lack of oil Oil breakdown Dirty air cleaner element Vacuum leaks

5. Scuffing or scoring (scratches and voids in the ring face)

Lack of oil Oil breakdown Too rich air-fuel mixture causing the oil film to be washed away and allowing the formation of carbon deposits Overheating Distorted cylinder bore Improper cylinder wall finish Improper piston clearance Improper ring end-gap (indicated by polished ring ends) Detonation High-speed operation

6. Broken rings

Worn piston ring grooves Detonation Excessive cylinder wall ridge Improper installation

7. Glazing

Improper ring seating

When new rings are installed, they should be checked for side clearance as discussed, and end-gap measurements.

Inspecting Piston Pins As discussed earlier, the piston pin and pin boss are subjected to severe operating conditions. Compounding this is the difference in expansion rates between the steel piston pin and the aluminum piston. A steel pin expands about 0.0003 inch (0.008 mm) for every 508F (288C) (increase in temperature). The diameter of the bore may increase 0.0006 inch (0.02 mm) during the same temperature increase. Consequently, proper clearance is critical. Manufacturers vary concerning recommended procedures for checking pin clearance and how much clearance is allowed. For example, Chevrolet suggests measuring the pin diameter and bore diameter; any clearance over 0.001 inch (0.025 mm) requires

Special Tools Micrometer Piston pins may be called wrist pins. Classroom Manual Chapter 13, page 261

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Figure 13-24  Measuring piston pin clearance.

Special Tools Rod vise Dial bore gauge Telescoping gauge Micrometer Rod aligner Press

replacement of the pin and piston. Pontiac says the pin will fall through the bore with 0.0005-inch (0.01-mm) clearance but will not with 0.0003 inch (0.008 mm). Some import manufacturers check pin and bore wear by holding the piston and attempting to move the connecting rod up and down. Any movement felt indicates wear. Feel is not always a reliable method. If you have any doubts, measure the clearance. Measure the pin using the recommended procedure for the engine being serviced (Figure 13-24). With the pin removed, visually inspect it for wear. Use your hands to feel for scuffing or scoring. If there is any wear, the pin must be replaced. Seized or scored piston pins are generally caused by overheating of the piston. This can be caused by poor cooling system operation and improper combustion due to preignition or detonation. These overheating conditions cause lubrication failures of the pin.

Inspecting Connecting Rods

Big end refers to the end of the connecting rod that attaches to the crankshaft. Small end refers to the end of the connecting rod that accepts the piston pin.

Caution The connecting rod and cap are manufactured as a unit and cannot be interchanged. Mark the cap and rod to maintain the original position.

The connecting rod is subjected to extreme operating conditions. As discussed earlier, the speed of the piston assembly is constantly changing between TDC and bottom dead center (BDC). These speed changes result in g-loads (1 g is equal to the force of gravity at the Earth’s surface) that literally stretch and compress the connecting rod every stroke; for example, an engine running at 6,000 rpm can exert 2,440 g of tension at TDC and compress the rod with 1,300 g at BDC. These forces can deform the two bores and/or bend the ­connecting rod. Under extreme conditions, the connecting rod can break apart. Before a connecting rod is accepted for reuse, it must be carefully inspected and ­measured. Both the big-end and small-end bores should be inspected for clearance, ­out-of-round, and taper. Most of the wear of the big-end bore occurs in the cap and in a vertical direction. In addition, the rod should be checked for center-to-center length. SERVICE TIP  It is a good practice to measure the crankshaft big-end bore on new connecting rods before installing them.

When measuring the inside diameter of the big end, assemble the cap to the rod, ­leaving the nuts loose. Locate the rod into a soft jaw vise or a special rod vise, with the jaws covering the parting line (Figure 13-25), and torque the cap nuts to specifications. This procedure ensures that the cap and rod are properly aligned with each other. The easiest way of measuring the bore is to use a dial bore gauge. If an inside micrometer or telescoping gauge is used, measure the diameter in two or three directions and near each end of the bore (Figure 13-26) to obtain out-of-round and taper measurements. The greatest amount of out-of-roundness will occur in the cap and in a vertical direction. Note: Some

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Connecting rod

Figure 13-26  Measure the big-end bore for wear, taper, and out-of-round.

Figure 13-25  Using a rod vise to align the rod to the cap before torquing the cap bolts.

manufacturers will specify directions for measuring connecting rods for out-of-round and taper at different areas in the big-end bore. Inspect the small-end bore in the same manner as the big-end bore. Use a dial bore gauge to measure clearance, out-of-round, and taper. If the piston assembly is designed with a press-fit pin in the connecting rod, the bore must be the correct size to provide an interference fit. In addition, any scuffing or nicks in the bore may inhibit the piston from rocking properly. Sometimes the bore can be honed to a larger size to accept an oversized piston pin. SERVICE TIP  If the rod bearing spun in the bore, an accurate bore diameter may not be obtainable. In this case, it may be necessary to hone the bore until the scoring is removed and then measure it. The bore can be machined to restore original bore diameter instead of replacing the rod.

Full-floating piston pins ride in a bronze bushing pressed in the pin bore of the connecting rod. These bushings should be replaced as a matter of standard procedure. The old bushing is pressed out and a new one is pressed in. The new bushing should be measured for clearance and corrected by honing if necessary. After honing the bushing, recheck it for taper. Taper can result if the hone is not perfectly straight with the bore. If there is more than 0.0002-inch (0.005-mm) taper, press out the bushing and install another one. Bores should be checked for parallelism and twist (Figure 13-27). To perform this task, install the piston pin into the rod without the piston, attach the cap to the rod, and torque the bolts while the cap and rod are held in alignment. Install the rod assembly onto a special alignment fixture with the thrust side of the rod facing out (Figure 13-28). Next, locate the bend indicator fixture against the piston pin. The fixture straddles the connecting rod, and this fixture should fit squarely against the piston pin. If a feeler gauge can be inserted between the fixture and the piston pin, the rod is twisted or bent. Some manufacturers recommend the cap bolts or nuts holding the connecting rod assembly together be replaced whenever the piston assembly is removed from the engine. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Bend must be within specifications

Twist must not exceed specifications

Figure 13-27  Connecting rod bend and twist must be checked before reusing the rod.

Figure 13-28  Using a rod aligner to measure twist and bend. When installing the rod to the aligner, the thrust side must be facing outward.

Check the TSBs from the manufacturer for specific information. After completing the bigend bore measurements, remove the bolts by pressing them from the rod (Figure 13-29). Inspect the area around the bolt holes for indications of stress cracks. This area is the weakest part of the connecting rod and is subject to fractures. If there are any cracks, replace the rod. Most manufacturers recommend that connecting rods be replaced as a set. Some connecting rods have oil jets or “squirt” holes to provide cylinder wall lubrication (Figure 13-30). Clean these holes with a proper size drill bit or torch tip cleaner. The following chart lists some common connecting rod failures and their causes: Failure

Cause

1. Big-end breakage

Improper cap bolt torquing Bolt breakage Connecting rod failure Excessive bearing clearance Nicks in the rod Hydrostatic lock Detonation

2. Rod bolt failure

Improper torquing Reusing rod bolts

3. Bent or twisted rods

Hydrostatic lock Seized piston pin Excessive compression ratio Detonation

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Connecting rod

Squirt hole

Piston

Figure 13-29  Pressing the cap bolts from the ­connecting rod.

Figure 13-30  A “squirt” hole is used to lubricate the cylinder wall and keep the piston head cool.

PISTON ASSEMBLY SERVICE Service to the piston assembly is usually confined to connecting rod reconditioning; ­however, the piston may require the installation and sizing of piston pin bushings. Some procedures such as piston pin bore enlarging, skirt knurling, and ring groove repairs can also be performed. These operations are not very common and are mainly used for special applications, such as heavy-duty diesel and marine engine applications.

Reconditioning Connecting Rods If the connecting rod fails inspection, it is not always necessary to replace it. A connecting rod can often be reconditioned. The following procedures may need to be performed on a connecting rod before it is returned to service: ■■ Replacing rod bolts ■■ Straightening ■■ Resizing the big-end bore ■■ Resizing the small-end bore ■■ Installing bushings into the small-end bore ■■ Beaming Before reconditioning the rods, inspect the thrust surfaces on the sides of the big-end bore. If there are any nicks or gouges, they should be dressed to provide proper seating in the grinder. Nicks and gouges are also stress risers; if they are not removed, the rod may fail prematurely. Connecting rod reconditioning is usually done at a machine shop. A technician should always consider the costs associated between reconditioning rods and purchasing new rods. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Cap Bolt Replacement.  It is a good practice to replace the connecting rod bolts whenever the rods are removed from the engine. If the big-end bore requires reconditioning, the bolts will have to be removed to perform some of the machining operations; however, if the rod requires straightening, straighten the rod before replacing the bolts. Most connecting rod bolts are press fit into the connecting rod. It is best to press both bolts out at the same time instead of attempting to knock them out with a hammer. They should come out with little pressure. If excessive pressure is required, back off the press ram. Continuing to increase pressure may break or bend the connecting rod. Use a connecting rod heater to heat the rod, and try pressing the bolts out again. After the caps and rods are machined, new bolts can be installed. When installing the bolts, it is important to protect the parting surface of the rod. A fixture can be made or purchased for installing the bolts (Figure 13-31). With the rod located over the fixture, the bolts can be seated with a punch and hammer.

Special Tools Connecting rod straightening fixture Bending bar

Special Tools Rod honer Rod grinder Rod vise Dial bore gauge

WARNING  Wear approved eye protection when performing this task. Do not stand in front of the connecting rod; stand to the side.

Straightening Connecting Rods.  Even though slight warpage of the connecting rod can be corrected by straightening, do not perform this operation if replacement rods are readily available. Liability and cost are factors you need to consider when deciding on this procedure. If the inspection of the rod indicates it is bent or twisted, it may be possible to straighten it. One method of correcting bend and twist is cold bending. This can be manually performed using a special holding fixture (Figure 13-32). When performing this procedure, it is important not to nick or scratch the rod. Nicks and scratches weaken the connecting rod and may lead to possible breakage. Begin by determining the direction of bend or twist. Most bends in the rod will be located near the small-end bore. Place the connecting rod into the straightening fixture using the correct size big-end and small-end adapters. Install the cap, and torque the cap bolts to specifications. Select the correct size bending bar. It should closely fit the rod to prevent nicks and scratches. Use the bar to bend the rod in small increments. Measure the progress on a rod alignment fixture. Resizing the Big-End Bore.  Big-end bores can be reconditioned using two methods: oversizing the bore or returning the bore to original size. The method used depends on the amount of wear and damage in the bore.

Connecting rod

Figure 13-31  Using an installation block to press in the new rod bolts ­protects the parting surface.

Figure 13-32  Cold straightening a connecting rod using a special holding fixture.

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Figure 13-33  Installing the rod into the grinder. Make sure it is square so equal amounts are removed from both ends.

WARNING  Always wear approved eye protection when grinding the caps and rods.

If it is determined that the bore is to be returned to its original size, grind the parting surfaces of the rod and cap to make the vertical diameter of the bore about 0.002 inch (0.050 mm) smaller. When grinding the parting surface of the rod, remove only enough material to restore the surface. The procedures for removing material from the cap and the rod are the same. First, remove the cap bolts. Place the workpiece in the grinder so it is resting on the squaring rod (Figure 13-33). Tighten the machine’s vise to secure the workpiece. It is important that the workpiece be secured so the grinding wheel removes an even amount from both ends. If unequal amounts are removed, the cap and the rod will not be square. Back off the feed wheel to be sure the grinding wheel will not contact the workpiece at this time. Position the workpiece over the grinding wheel, and adjust the feed wheel until the parting surface just comes into contact with the stone. Swing the workpiece out of the way. Turn on the motor and swing the workpiece over the grinding wheel. This is the zero cut. Adjust the feed wheel to remove 0.002 inch (0.050 mm), and take another pass over the stone with the workpiece. If more metal must be removed, adjust the feed wheel to the desired amount, and swing the cap over the stone. Do not remove more than 0.002 inch (0.050 mm) at a time. Then install the connecting rod cap and torque it to the specified value. To keep the cap and rod assembly straight, use a rod vise when installing the cap. Use a dial bore gauge to determine how much material must be honed. Then select the honing mandrel that fits the bore diameter. Install the mandrel to the machine, and test the feed of the stones by turning the machine on and adjusting the feed back and forth. The stones should go in and out. Set the spindle speed. If the bore diameter is over 2 inches (50 mm), the speed should be set to 200 rpm. Next, set the cutting pressure. On many machines, use a dial setting of 2 for rough honing and 1 to finish honing the bore. Then rotate the spindle until the mandrel shoes are facing up, and loosen the clamp that secures the shoes. Place a connecting rod onto the connecting rod reconditioner (Figure 13-34). Depress the foot pedal, and adjust the feed dial until the shoes expand and lock the rod in place. Retighten the shoe clamp screw; then back off the feed until the dial indicator reads zero. This provides a zero set to determine how much the bore is being honed.

Throughout this ­procedure, the cap or the rod is referred to as the workpiece.

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Torque rod

Figure 13-34  This rod reconditioning machine can resize the big- or small-end bore.

Figure 13-35  Position the rod against the torque rod. The torque rod should be on a flat surface as close to the small-end bore as possible.

Adjust the torque rod to support the flat surface of the rod as close to the s­ mall-end bore as possible (Figure 13-35). Adjust the coolant flow over the workpiece. Use the foot pedal to control the machine. Stroke the rod the entire length of the stones while ­maintaining stone pressure by turning the feed dial. Observe the honing dial to measure the amount of material removed. Use a slower speed to provide a smooth finish. Do not use any additional stone ­pressure. After the bore has been resized, measure the bore diameter. SERVICE TIP  Honing two connecting rods at the same time helps keep the bores square. The two rods are held next to each other during the honing operation.

It is recommended that the bores be rechamfered to restore the original oil throw-off properties. Remember the following considerations when reconditioning the big-end bore: ■■ Attempt to remove most of the metal from the rod cap instead of the rod. ■■ Removing metal from the rod reduces the center-to-center distance of the rod and the compression ratio of the cylinder. ■■ The center-to-center distance between rods should not vary more than 0.010 inch (0.254 mm).

Special Tools Press Bushing driver Expander bit Dial bore gauge Hone

WARNING  Always wear approved eye protection when honing the connecting rod bore.

If returning the bores to their original size will result in excessive center-to-center length reduction, it may be possible to bore or hone the big-end bore to accept an oversize bearing. This can be done only if oversize bearings are available. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Reconditioning the Small-End Bore.  The reconditioning method used on smallend bores depends upon the type of piston pin fit. Press-fit piston pins require about 0.001-inch (0.025-mm) interference. If the bore is worn, it will need to be resized to accept an oversize pin. This will require the pin boss in the piston to be oversize as well. Before performing this operation, be sure to weigh the cost of replacement versus the labor cost involved. WARNING  Always wear approved eye protection when performing this ­operation. Do not wear jewelry, and be sure to secure any loose clothing.

Full-floating piston pins ride in a bushing pressed into the small-end bore. This bushing should be replaced as a matter of common practice whenever the engine is being rebuilt. Press out the old bushing, using an adapter to prevent damage to the connecting rod. Press the new bushing into the bore, making sure that any oil holes in the rod and the bushing align to each other. If the bushing uses parting lines or slots to direct oil flow, install these lines to the minor thrust side of the rod. Once the new bushing is installed, it is sized to the pin. The first step is to expand the bushing using an expander bit (Figure 13-36). This seats the bushing into the bore. If this process is not done, proper heat transfer will not occur. To expand the bushing, select the correct size mandrel for the bushing. Set the spindle speed to 200 rpm, and rotate the pressure-setting dial all the way off. Locate the small-end bore over the mandrel. Direct the coolant flow into the workpiece. Use the foot pedal to start the spindle, and stroke the connecting rod back and forth over the mandrel. Adjust the feed dial until you feel the expander bit contact the bushing. Increase the feed dial two numbers while stroking the connecting rod. Remove the rod, and inspect the work. Next, use the facing cutter to remove any material from the outside of the bore. Finally, hone the bushing to fit the pin. The clearance is usually between 0.0003 and 0.0005 inch (0.008 and 0.013 mm). To do this procedure, start by determining the amount to be honed from each bushing. Adjust the pressure setting to 1, and follow the same procedure for expanding the bushing to hone the bushing to final size. Check piston pin fit on each bushing. If a bushing is too loose, remove it and install a new one.

The minor thrust side is the side away from the side of the rod that is stressed during the power stroke.

Expander bit

Expander bar

Bushing

Figure 13-36  The bushing should be sized first with an expander bit to set the bushing into the rod properly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Piston and Connecting Rod Reassembly If the engine is not going to be balanced, the pistons and the connecting rods can be assembled at this time. If the engine is going to be balanced, assemble the pistons and the connecting rods after each component is weighed separately and matched. Remember to keep all pistons, rods, and pins identified to the cylinder bore in which they will be installed. In addition, check the service manual to determine if the pistons are offset and the proper orientation of the rod to the piston. Also, the connecting rod may have oil spit holes or jet valves that must be installed in the proper direction. The spit hole is used to squirt oil onto the cylinder walls and under the piston head to keep it cool. V-type engines typically use offset connecting rods. If these are installed backward, the engine may lock up and not rotate. Rod bearings are usually offset in the rod bore toward the middle of the crank journal. This is so the edges of the bearings will not rub on the fillets. Before beginning the reassembling procedure, double-check the rods and pistons. They must be absolutely clean. As each piston is fitted to the rod, double-check the ­clearances. Rod bearing clearance can be checked by installing the rod bearings into the connecting rods and torquing the cap bolts to specifications. Measure the inside diameter of the bearing and the outside diameter of its crankshaft journal. Compute the difference between these readings, and divide it by 2 to obtain the oil clearance. Piston-to-connecting-rod installation methods depend on whether the pin is full floating or press fit.

Special Tools Press Piston pin installation set Rod heater

Classroom Manual Chapter 13, page 258

Full-Floating Pins.  Installing pistons with full-floating pins does not require any special tools. These types of pins can generally be pushed in using your hands. Coat the pin, piston bore, and small-end bore with light oil or assembly lube prior to installation. Fit the piston pin into one side of the piston bore until it enters into the center of the piston about 1/16 inch. Next, locate the rod into the piston, making sure it is facing the proper direction. Align the small-end bore with the protruding piston pin, and push the piston pin through the connecting rod bore and into the other piston bore. If necessary, tap the pin in with light hits with a plastic hammer. Check to be sure the pin is free to rotate in both the piston bosses and the connecting rod. Finally, install the snap rings. It is very important to install the retaining clip properly. If it is installed improperly, the pin can come out and damage the cylinder bore. Handle the snap rings carefully. Do not overstress them by compressing them more than necessary. The open end of the snap ring should face toward the bottom of the piston. This places the strongest part of the snap ring in the portion of the pin boss receiving the highest stress. In addition, some snap rings are tapered or chamfered and must be reinstalled in the proper direction to prevent the pin from coming loose. Press-Fit Piston Pins.  Press-fit piston pins can be installed using a hydraulic press or by heating. Be sure to use the proper tools and equipment when pressing in the pin. The heating method expands the small-end bore of the connecting rod to allow the piston pin to be slip fit. The small end of the connecting rod is raised to a temperature of about 4258F (2048C) using a special rod oven.

Installing Piston Rings

Special Tools Ring expander

Installing piston rings is usually an easy task; however, improper procedures can lead to early engine failure. Take the time to do the task properly and make all required measurements and checks. First, double-check to be sure the piston ring grooves are thoroughly cleaned. Next, check and correct ring end gap. Proper ring gap is critical due to expansion of the piston, rings, and cylinder bore during engine running conditions. If the end gap is too wide, compression can escape; if it is too narrow, scuffing or ring breakage can result. To check ring end gap, place the ring into the cylinder bore that it will be installed into later. Use the piston to slide the ring to the specified depth in the cylinder. The piston head

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Piston ring

End gap

Figure 13-38  Measure the ring end gap using feeler gauges.

Figure 13-37  Install the ring into the bore toward the bottom of ring travel, using a piston to be sure it is square.

will keep the ring square in the bore so that accurate measurements can be made. If the cylinder has been honed or bored to correct parallelism, the ring can be installed anywhere in the cylinder. If the bore has not been reconditioned, locate the ring where specified in the service manual. Some manufacturers require gap checks to be made at the top of ring travel, while others require it at the bottom of ring travel (Figure 13-37). Use a feeler gauge to measure the width of the gap (Figure 13-38). The end of the gap is tapered, so be sure to measure at the outer edge to obtain accurate measurements. If the gap is too wide, use oversize rings. If the gap is too narrow, use a file or ring grinder to carefully remove some material. Check all rings that are to be installed into that cylinder. If the rings are not to be installed immediately onto the piston, identify them to the cylinder to maintain order. Ring gap specifications vary according to the material the ring is constructed of and the diameter of the piston. Following is a general specification chart that may be used if manufacturer specifications are not available: Standard Iron Rings Diameter

Ring Gap Clearance

2.000 in. to 2.999 in.

0.007 in. to 0.017 in.

3.000 in. to 3.999 in.

0.010 in. to 0.020 in.

4.000 in. to 4.999 in.

0.013 in. to 0.025 in.

5.000 in. to 5.999 in.

0.017 in. to 0.028 in.

6.000 in. to 6.999 in.

0.020 in. to 0.032 in.

High-Strength Iron Rings 3.000 in. to 3.999 in.

0.010 in. to 0.026 in.

4.000 in. to 4.999 in.

0.014 in. to 0.030 in.

5.000 in. to 5.999 in.

0.017 in. to 0.034 in.

6.000 in. to 6.999 in.

0.021 in. to 0.038 in.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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SERVICE TIP  A rule of thumb for ring end gaps is 0.003 to 0.004 inch for each inch of cylinder bore diameter.

If any of the end gaps are too narrow, the gap can be increased by a file or ring gap cutter. If a file is used, cut from the outside of the ring toward the center. Correct all rings requiring wider gaps. If the ring gap is too wide, it is possible that the gap was checked with the ring in a slightly worn area of the cylinder bore; for example, if the ring were into an area of the bore that was 0.002 inch (0.05 mm) oversize, the gap would be increased by 0.006 inch (0.15 mm). As a result, a ring with a 0.018-inch (0.46-mm) gap would measure 0.024-inch (0.61-mm) clearance. Also, if the bore diameter were increased, oversize rings would have to be used. Rings are available for standard 0.020, 0.030, 0.040, and 0.060 inch oversizes. If a 0.010-inch oversize piston is installed, a standard size ring is used. Metric oversizes are 0.50, 0.75, 1.0, and 1.5 mm. SERVICE TIP  You cannot file or grind the end of most chrome rings; the coating will chip away. Follow the instructions that are provided in the ring package.

The oil control rings can generally be installed by hand (Figure 13-39). Install the expander ring first. The two ends of the expander must contact each other without any gap. Make sure the two ends do not overlap. Rotate the expander until the ends are 90 degrees from the piston pin. Next, install the upper oil ring side rail. Start the ring by placing one end between the ring groove and the expander. Hold this end in place while working the ring around the piston and into the groove. Locate the end gap of this ring 45 degrees from the end of the expander. Now install the lower side rail in the same ­manner. Locate the end gap of this rail 180 degrees from the end gap of the top rail. The oil ring side rails must be free to rotate after installation. SERVICE TIP  It may be tempting sometimes to install oversize rings to compensate for worn cylinders instead of boring the cylinder. This is not a good idea, because the taper of the worn cylinder will cause the rings to lock up as they travel down the cylinder bore.

Upper rail gap Lower rail gap

Ends butting

Figure 13-39  Installing the oil control ring assembly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Figure 13-40  Use a ring expander, so you do not twist the ring or scrape the piston.

611

Figure 13-41  A damaged compression ring is the result of trying to roll the ring into the ring groove.

Starting with the bottom compression ring, use a ring expander to install the rings into the piston grooves (Figure 13-40). The ring expander prevents the ring from being rolled onto the piston. Rolling a ring will result in distortion (Figure 13-41). Be careful not to overexpand the ring; doing so may cause it to crack. Be sure to note any markings indicating that the rings are directional (Figure 13-42). With the rings installed, use a feeler gauge to measure ring-to-groove clearance, and compare the measurement to specifications (Figure 13-43). After the rings are installed, the end gaps should be staggered. This is done to prevent compression leakage. Follow the manufacturer’s recommendations for proper location of ring end gaps (Figure 13-44).

Special Tools Tap set Core plug driver Bushing driver Hone kit

SERVICE TIP  Do not install the core plug for the back of the camshaft until the camshaft is installed.

SERVICE TIP  Some manufacturers require threaded inserts be installed on aluminum blocks before reassembly.

Figure 13-42  Most directional rings are marked in some way to identify proper installation direction. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Figure 13-43  The proper ring side clearance allows the ring to seat properly in the piston.

Oil ring gap Second ring gap

90°

Spacer gap

15° 15° Oil ring gap Do not position any ring gap at piston thrust surfaces.

90°

Top ring gap

Do not position any ring gap in line with the piston pin hole.

Figure 13-44  Position the ring end gaps to prevent compression leakage.

Special Tools Micrometer Three-cornered scraper Flex hone Core plug driver Dial indicator

Special Tools To assist in the installation of the camshaft, install 4-inch bolts into the threaded holes at the front of the camshaft. Use the bolts to rotate the camshaft and to push it into the engine block.

ENGINE BLOCK PREPARATION Before assembling components in the engine block, use the following checklist to be sure that they are properly prepared: 1. Chamfer the edge of the cylinder head bolt holes to prevent cylinder head gasket deformation during the torquing process. 2. Inspect all sealing and gasket surfaces for irregularities, nicks, scratches, and so forth. 3. Clean the threads of all bolt holes, using the correct size bottoming tap. 4. Inspect all bearing surfaces for nicks, galling, or sharp edges. 5. Check all notes made during the inspection to be sure all machining operations have been performed. 6. Clean the engine block. 7. Install the core and oil gallery plugs (Figure 13-45). If the engine uses any bushings inside of bores, such as the distributor shaft bore, use a bushing driver to replace them. It may be necessary to hone the bushing to obtain proper fit. Driving the bushing may cause it to deform slightly on the edge. Use a knife or scraper to remove this edge.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

New oil gallery plug

613

New core plug

Figure 13-45  With new core plugs and oil gallery plugs installed, the block is clean and ready for reassembly.

Installing OHV Camshafts, Bearings, and Balance Shafts Installing OHV Camshaft Bearings.  The camshaft bearings should be installed before installing the crankshaft assembly. Camshaft bearings are press fit into the engine block and are often sized differently for the different bearing journals. Installing OHV camshaft bearings requires special tools. The most common type of tool used is a universal installation tool. This type of tool uses an expanding mandrel that fits snug and tight against the bearing. The mandrel is connected to a driver, and a h ­ ammer is used to press the bearings in aligning the oil hole in its proper position.

Caution Do not use emery cloth to remove high spots. The grit can embed in the bearing surfaces and damage the journals.

SERVICE TIP  Long in-line engine blocks attached to an engine stand may flex enough to prevent free camshaft rotation. Try supporting the front of the engine also before condemning the camshaft or bearings.

Installing OHV Camshafts and Balance Shafts.  When sliding the camshaft into the bearings, be careful to protect the journals and bearings. The following is a guide to typical procedures for installing the camshaft into an OHV engine: 1. Determine oil clearance between the installed camshaft bearings and the camshaft journals, and compare with specifications. 2. Use a rag soaked in solvent to remove any coating on the camshaft journals. Be careful not to remove the coating on the lobes. Lubricate the journals with engine oil or assembly lube before fitting the camshaft into the block. 3. Install the camshaft, preventing any contact between the lobes and the bearings. When the camshaft is fully seated in place, spin it to ensure free rotation. If rotation is impaired because of high spots on the bearings, they can be removed using a threecornered scraper (Figure 13-46). Slight corrections to the bearings can be made with a flex hone. Make sure to clean the engine block after performing these operations. If the bearings are not the cause of the binding, the camshaft may be bent. 4. Apply sealer to the outer edge of the rear core plug, and install the plug with the convex side out (Figure 13-47). Drive the plug to the specified depth. Once the core plug is installed, use a dull punch to deform it slightly. This increases the ­tension applied to the outer edges to provide a positive seal. After the core plug is installed, rotate the camshaft to be sure the plug is not causing interference. 5. Install the camshaft retainer plate. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Engine block

Camshaft plug

Figure 13-46  Use a three-corner scraper to remove high spots in the ­camshaft bearing.

Camshaft end play is the measure of how far the camshaft can move lengthwise in the block.

Special Tools Torque wrench Plastigage Dial indicator Pilot bushing/ bearing puller Pilot bushing/ bearing driver Micrometer

Figure 13-47  The camshaft plug is installed at the rear of the block.

6. Measure camshaft end play, and correct it if needed. Install a dial indicator to measure the lateral movement of the camshaft; then use a screwdriver to gently pry the camshaft back and forth. The total indicated reading (TIR) of the indicator is the amount of end play. Some engines use shims to correct end play. If shims ­cannot be used, the camshaft may need to be replaced. 7. Apply special camshaft break-in high-pressure lubricant onto the lobes, being ­careful not to get any onto the journals. 8. Lubricate the balance shaft journals and bearings with the vehicle manufacturer’s specified engine oil, and install the balance shaft. 9. Apply sealer to the outer edge of the balance shaft rear expansion plug. Position this plug with the convex side out, and drive the plug into the rear expansion shaft bearing bore to the specified depth. Use a hammer and punch to strike the expansion plug in the center until it is slightly deformed. 10. Install the camshaft and balance shaft matching gears so the timing marks are aligned. 11. Install the camshaft drive gear and timing chain so the timing marks are properly aligned (refer to Figure 13-48). Camshaft to crankshaft Align marks

Balance shaft to camshaft

Align marks

Figure 13-48  Proper balance shaft and camshaft timing. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

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12. Tighten the balance shaft gear and camshaft gear retaining bolts to the specified torque. 13. Lubricate the camshaft gears, balance shaft gear, timing chain, and crankshaft gear with the specified engine oil.

PHOTO SEQUENCE 28

Typical Procedure for Checking Main Bearing Oil Clearances

P28-1  After thoroughly cleaning the engine block and bearing bores, gather the tools you will need. This includes oil, the service manual, plastigage, and a torque wrench.

P28-4  After placing the plastigage on the other journals, torque the crankshaft main bearing cap bolts to specification using the manufacturer’s provided sequence. Avoid ­turning the crankshaft during this step!

P28-2  Install the new bearings in the block. Avoid touching the front and back sides of the bearings, and do not lubricate the bearing just yet. Using tight-fitting rubber gloves is helpful for keeping the grease from your fingers off the bearings.

P28-5  Remove the main bearing caps, in sequence, and check the width of the ­plastigage. The plastic strip will widen when it is squeezed, due to the bearing cap providing pressure on it.

P28-7  After cleaning all of the plastigage up from the bearings and the caps, thoroughly ­lubricate the new bearings before final ­assembly. Some technicians use a heavier engine assembly lube.

P28-3  Cut off a small piece of plastigage and install it lengthwise on the crankshaft journal.

P28-6  After recording all of your measurements, remove the plastigage by scraping it off with your fingernail in a clean shop rag.

P28-8  Torque down the main caps one at a time using the manufacturer’s provided sequence. Check to make sure that the crankshaft turns after each one is fastened down.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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SERVICE TIP  If the balance shaft is not properly timed, severe engine vibrations will occur.

INSTALLING THE MAIN BEARINGS AND CRANKSHAFT Caution If engine components are not properly ­lubricated during engine assembly, rapid component wear occurs during the first few seconds of engine operation.

It is a good practice to replace the pilot bushing or bearing installed in the end of crankshafts used with manual transmissions. The old bushing or bearing is pulled out using a special puller adapter (Figure 13-49). Remove any burrs inside the cavity, being careful not to enlarge the size of the bore. Then drive the new bushing or bearing into place (Figure 13-50). Be careful to start the pilot straight. The pilot should enter the cavity with moderate hammer blows. Do not use excessive force to drive the pilot in. Soak the bushings in oil before installing them. Pilot bearings may have an integral seal that must be installed in the correct direction. Most pilot bearings are lubricated during assembly and do not require any additional lubrication during installation.

Pilot bushing

Figure 13-49  Using a puller to remove the pilot bushing or bearing.

Pilot bearing Driver tool

Bearing seal must face the transmission

Figure 13-50  Installing the pilot bushing. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

SERVICE TIP  On vehicles with a manual transmission, a worn pilot bearing or bushing causes a rattling, growling noise with the clutch disengaged.

SERVICE TIP  A pilot bushing can be forced out by filling the cavity with heavy grease and then using a hammer to hit a dowel the same size as the ID of the bushing. The grease cannot compress and will push the bushing out.

Make sure that proper main bearings are selected for the engine. If no machining was required on the crankshaft journals or bearing bores, refer to the service manual for proper bearing selection. Some manufacturers use a select fit bearing selection procedure. A code that is used to select the bearings is usually stamped on the engine block and the crankshaft (Figure 13-51). A chart is then referenced for the proper bearing selection (Figure 13-52). Some manufacturers use color coding instead of numbers. In preparation for installation of the main bearings and the crankshaft, use the engine stand to rotate the block so the crankcase is facing up. Before installing the crankshaft main bearings, clean the block saddles, caps, and bearings thoroughly. When installing the bearing inserts, hold them between the thumb and forefinger and slightly squeeze the ends together. Install the bearing insert, and push in on the ends to be sure it is fully seated. When installing the crankshaft, lift it by the harmonic balancer journal and the bolts threaded into the rear flange. As the crankshaft is lowered into the bearings, keep it parallel to the bearings and lower it straight down. If it is installed properly, the crankshaft will seat squarely and will be supported by the bearings. Main bearing oil clearance must be checked and corrected, if needed. There are three common methods of measuring oil clearance. The first is to install the bearings into the block and torque the cap bolts to the assembled torque specification (the crankshaft is not installed at this time). Measure the inside diameter of the bearings, and record the reading. It is important to measure the bearing vertically in the engine since most main bearings are thinner at the parting lines. Subtract the outside diameter size of the corresponding main-bearing journals to get total clearance. Actual clearance is obtained by dividing this value by 2.

Block bearing select code

Front of engine

xxxxx

Crankshaft bearing select code

Figure 13-51  Engines with select bearings usually have codes stamped on the block and crankshaft to identify the proper ­selection of bearings. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Cylinder Block Code

91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68

98 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2

99 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2

00 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2

01 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2

02 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2

03 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 3

04 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 3 3

05 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 3 3 3

06 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3

07 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3

08 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3

09 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3

10 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3

11 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3

12 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3

13 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3

14 1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3

15 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3

16 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3

17 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3

18 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3

19 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

20 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

21 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

Figure 13-52  Bearing selection chart.

The second, and most common, method of measuring oil clearance is to use Plastigage. Plastigage is a piece of plastic that is compressed by the bearing and assembly when it is installed. The compression of the plastic makes it wider and the width is what is measured. That measurement is very accurate and represents the oil clearance between the bearing and the crankshaft. Plastigauge is actually a brand name for a plastic precision clearance gauge. Although it is not as accurate as measuring oil clearance with a micrometer, plastigage is usually accurate enough for most engine applications. Follow Photo Sequence 28 for using plastigage to determine oil clearance. The third method requires several measurements but is the most accurate. Begin by measuring the wall thickness of the bearing insert. Measure the insert in the center where there is no taper. Double the measured dimension so both sides of the journal are considered. Also measure the journal diameter and bore diameter. Subtract all measurements from the bore diameter to obtain total clearance (Figure 13-53). Divide total clearance by 2 to obtain actual clearance.

Housing bore Bearing wall thickness (0.061) 3 2 Bearing assembled inside diameter Shaft diameter Oil clearance

2.124" –0.122" 2.002" –2.000" 0.002"

Figure 13-53  Example of mathematically figuring oil clearance. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

619

Main bearing caps

Main bearing cap bolts

Main bearing lowers

Crankshaft

Front of engine

Cylinder block assembly

Main bearing uppers

Figure 13-54  Installing main bearing caps.

Refer to Photo Sequence 29, and use the following list as a guide to installing the main bearings and the crankshaft (Figure 13-54): 1. Make sure the bearings are the correct size for the journals and bores. 2. Install all upper bearing inserts into the block. These inserts have oil holes and grooves that must be properly aligned with the block. Make sure to install the thrust washer into the specified saddle. 3. Install the lower bearing inserts into the caps. 4. Inspect the cap bolts for damage. 5. Measure bearing clearance. 6. If the rear main seal is a two-piece lip seal, install the pieces into the block and rear cap. Make sure the lip is facing into the crankcase. 7. Lubricate the inside surfaces of the bearing inserts with a film of engine oil. 8. Install the crankshaft, caps, and bolts. If required by the manufacturer’s service instructions, apply anaerobic sealer between the rear cap and the cylinder block (Figure 13-55). Place the main bearing caps over the crankshaft journals starting at the rear journal and working toward the front of the engine. Make sure that each cap is installed in the correct location and in the proper direction. Register the main bearing caps by tightening the cap bolts by hand while rotating the crankshaft.

Registering the main bearing caps is done by tightening the cap bolts using hand pressure only while rotating the crankshaft. This squares the cap to the block before the bolts are torqued.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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PHOTO SEQUENCE 29

Typical Procedure for Installing the Main Bearings and Crankshaft

P29-1  Thoroughly clean the engine block and bearing bores.

P29-2  Install the new bearings in the block. Avoid touching the front and back of the ­bearings, and do not lubricate the back.

P29-3  Install the lower bearing halves into the bedplate or the main caps.

P29-4  Thoroughly lubricate the new bearings after they have been put into their bores and before laying the crankshaft in place. Some technicians use a heavier engine assembly lube.

P29-5  Lay the perfectly clean crankshaft in place.

P29-6  Use the proper sealant as specified on the crankshaft bedplate.

P29-7  Torque the bedplate (or main caps) in the proper sequence and stages to the final torque. Double-check the final torque to be sure that you did not miss any bolts. It is a good idea to spin the crankshaft after each main cap is fastened.

P29-8  This engine uses six-bolt main caps; be sure to torque all the bolts properly.

P29-9  With the crankshaft bolted in, confirm that the crankshaft rotates smoothly and has end play within the specified range. Use a dial torque wrench to check rotating (spinning) torque.

9. With the main bearing cap bolts fingertight, pry the crankshaft back and forth to align the thrust bearing (Figure 13-56). 10. Engines with bedplates (one-piece main bearings) may also require the use of liquid gasket maker (Figure 13-57). In some instances, installation of the bedplate must be done within 6 minutes after the sealant is applied. 11. The crankshaft should rotate freely, with no binding or restrictions. Correct any problems before continuing. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly Anaerobic sealant

19 mm (0.75 in.)

6 mm (0.25 in.)

Rear main bearing cap

Figure 13-55  Apply sealant to the rear main bearing cap, if indicated. Hold crankshaft forward

Hold crankshaft forward

Pry cap backward

Pry forward Thrust bearing

Tighten bolts

Thrust bearing

Pry crankshaft forward

Tighten cap

Pry cap backward

Figure 13-56  Aligning the thrust bearing.

6-mm gap

Bedplate 6-mm gap

Figure 13-57  One-piece main bearing caps may require a special application of sealant.

12. Torque the bolts of the first cap in sequence to the specified value (Figure 13-58). Check crankshaft rotation by rotating the crankshaft with a torque wrench. Note the amount of torque required to rotate the crankshaft during several revolutions. Read only rotating torque, not the amount of torque required to get the crankshaft to rotate. 13. Torque the next cap in the sequence, and check the rotating torque of the crankshaft again. 14. Continue to torque the cap bolts in sequence, making sure to check rotating torque after each cap is tightened. Watch for large increases in the torque required to rotate the crankshaft. If there is a large increase in the torque requirement, stop and locate the cause of the problem. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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622

Chapter 13 Front

1

9

5

8

4

3

2

10

6

7

Figure 13-58  Typical main bearing torque sequence.

Seal assembly Crankshaft rear seal installer

Figure 13-59  Installing a one-piece rear main seal.

15. After all the cap bolts are torqued, check the rotating torque of the crankshaft. It should not require more than 5 lbs.-ft. (6.75 Nm) to rotate the crankshaft. 16. If the engine uses a one-piece lip seal, install it (Figure 13-59). Some manufacturers require the use of a special pilot tool for installation. After the seal is located over the pilot tool, it is tapped into place with a plastic hammer. Other manufacturers may require the use of special drivers. 17. Check crankshaft end play (Figure 13-60). With the dial indicator set up to read lateral movement of the crankshaft, use a pry tool to move the crankshaft as far to the rear of the block as possible. Zero the dial gauge at this point; then force the crankshaft as far forward as it will go. The TIR must be within specifications.

SERVICE TIP  If all the engine needs is new main bearings, they can usually be changed with the engine still in the vehicle. When checking bearing clearance with plastigage, use a jack to remove the load from the crankshaft so accurate measurements can be taken.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

623

Figure 13-60  Check to be sure that crankshaft end play is within specifications. Too much end play will cause knocking on acceleration; too little could cause the crank to seize.

INSTALLING THE PISTONS AND THE CONNECTING RODS Begin the piston installation procedure by installing the bearing inserts into the connecting rods and caps, making sure the oil holes align and the tabs are properly located (Figure 13-61). Coat the cylinder walls with clean engine oil, and soak the piston head in a container of clean engine oil. If oil clearance is being checked using a micrometer, it is easier to measure the inside diameter of the bearing before the piston assembly is installed into the engine block. The cap bolts must be torqued to the specified value while the connecting rod and the cap are held in a rod vise to maintain alignment. In addition, oil clearance can be checked using plastigage. If bearing clearance is being measured using plastigage, do not apply oil to the bearings. Similar to crankshaft main bearings, connecting rod bearing clearances should always be checked with plastigage before continuing with reassembly. Do not apply any oil to these bearings during the measurement and measure one connecting rod at a time. After measuring and correcting for the bearing clearance on one rod, lubricate the bearing with engine oil or assembly lube and torque the cap down to specification. Check the rotating torque of the crankshaft assembly after each connecting rod is torqued to specification. This method will allow you to pinpoint any problems with a single connecting rod or bearing during reassembly. It may be easier to install the connecting rod caps if the crankshaft throw is located at BDC as each piston is installed, and to rotate the engine on the stand so the bore is horizontal. Cover the connecting rod bolts with a special guide or pieces of rubber hose to protect the cylinder walls and crankshaft-rod journals from damage (Figure 13-62). To prevent damage to the piston and rings, use a ring compressor to squeeze the rings together. Double-check to be sure that each piston is being installed into the correct corresponding bore and that it faces the correct direction. The pistons should go into the bore with a slight restriction. Using a hammer handle to tap the piston assembly into the cylinder will make installation easier (Figure 13-63). When installing the rod caps to the connecting rods, make sure to match the correct units, and make sure that they are facing the correct direction. If the rod is chamfered on one side, the chamfered side goes toward the fillet and the flat side toward the companion rod.

Special Tools Torque wrench Plastigage Micrometer Rod protectors Ring compressor Dial indicator

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Locating lug

Slot

Figure 13-61  Install the rod bearings into the cap and the rod. Be sure that the tab locks into the slot.

Figure 13-62  Cover the connecting rod bolts to protect cylinder walls and crankshaft-rod journals from damage.

Figure 13-63  Make sure that the piston ring compressor’s arrow is pointing in the correct direction, and make sure that the piston is facing the correct direction. Use a soft-handled hammer and tap the pistons in place. If you encounter resistance, stop and see if a ring has popped out; you can easily break a ring in this procedure.

When installing and torquing the cap bolts for the final assembly, coat the bolt threads with a thread locking compound. As each connecting rod is installed onto the crankshaft, tighten the cap bolts only fingertight. Check the rotating torque of the crankshaft as each piston is installed. This gives an indication of the interference between the piston rings and cylinder walls. If any of the pistons causes a large increase in turning torque, repair the cause before continuing. After all the pistons are installed, check the rotating torque and record it. SERVICE TIP  Some connecting rod bolts should be installed with only thread lubrication. Always check with the rod manufacturer for proper installation instruction.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

625

Figure 13-65  Use a feeler gauge to measure the clearance between two rods sharing a journal. Figure 13-64  Be certain to torque each of the rod bolts properly; one loose bolt could ruin an engine.

Figure 13-66  You can see the notches on the right of the pistons all facing forward on this engine.

Starting with the first connecting rod in sequence, torque the cap bolts (Figure 13-64). As the bolts are torqued, tighten them in small increments, alternating back and forth between the two bolts. After each piston assembly is properly torqued, rotate the crankshaft to check for binding. With all connecting rods torqued to specifications, recheck turning torque. The total increase in torque should not be more than 5 lbs.-ft. (6.75 Nm) above the value recorded earlier. After all piston assemblies are installed, use a feeler gauge to check connecting rod side clearance (Figure 13-65). Finally, flip the engine over and double-check to be sure that all your pistons are facing in the correct direction (Figure 13-66).

Classroom Manual Chapter 13, page 258

COMPLETING THE BLOCK ASSEMBLY Most of the measurement checks have been completed, and the block is ready to receive the oil pump, cylinder heads, valvetrain, valve timing units, and manifolds.

Special Tools Torque wrench

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Installing the Oil Pump The oil pump can usually be installed next. If the oil pump is integral to the front cover, it will be necessary to install the valve timing components first. Always replace the front cover oil seal using an appropriate driver (Figure 13-67). Use the following list to check progress as the oil pump is installed (Figure 13-68):

The pickup tube is used by the pump to deliver oil from the bottom of the oil pan. The bottom of the tube has a screen to filter larger contaminants.

1. Prime the oil pump before installing it by submerging it into a pan of clean engine oil and rotating the gears by hand. When the pump discharges a stream of oil, the pump is primed. 2. If a gasket is installed between the pump and the engine block, check to make sure that no holes or passages are blocked by the gasket material. Soak the gasket in oil to soften the material and allow for good compression. 3. Install the oil pump, making sure that the drive shaft is properly seated. Torque the ­fasteners to the specified torque value (Figure 13-69). 4. Bolt-on pickup tubes may use a rubber O-ring to seal them. Do not use a sealer in place of the O-ring. Lubricate the O-ring with engine oil prior to assembly; then alternately tighten the attaching bolts until the specified torque is obtained.

Installing the Cylinder Head If the engine is an OHC type, the cylinder heads must be installed before the timing components. On OHV engines, the timing components can be installed before the heads. The procedures for cylinder head installation are similar. On some OHC engines, the camshaft and valvetrain components can be installed into the head before the head is placed onto the engine block. Use the following checklist along with the appropriate service manual as the cylinder heads are installed.

Oil pump Bolt

Seal driver

Retainer

Intermediate shaft

Dowel

Engine block

Figure 13-67  Driving in a new seal.

Figure 13-68  Oil pump installation.

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Figure 13-69  This oil pump tightening specification was given in inchpounds. Torque to the correct value; the manufacturer has engineered the engine carefully.

Cylinder head gasket

8–9 mm

Dowel

Cylinder block

Figure 13-70  Alignment dowel installation.

1. Any bolts that enter into coolant or oil passages must have approved sealer applied to the threads. Make sure that the bolt holes are free of fluid and have clean threads. 2. Install any dowels that were originally equipped on the deck (Figure 13-70). 3. Locate any markings on the cylinder head gasket that identify the proper direction for installation (Figure 13-71). 4. Position the new head gasket over the dowels and check for proper fit. 5. Locate the crankshaft a few degrees before TDC so all pistons are below deck height. 6. Position the cylinder head over the dowels. On V-type engines, make sure that the ­correct head is installed onto the correct bank. Note: Some manufacturers ­recommend the use of guide pins to align the head(s) to the block. 7. Install and torque the cylinder head bolts. Most manufacturers specify multiple steps for torquing the head bolts. Follow these instructions to prevent warpage (Figure 13-72). Also follow the correct torque sequence. Torque-to-yield cylinder head bolts are used in many engines. These bolts must be tightened to the specified torque and then rotated a specific number of degrees. Torque-to-yield bolts must be replaced each time the cylinder head is removed and replaced.

Special Tools Torque wrench Alignment dowels

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Cylinder head

Dowel pin

Head gasket

FRONT

Engine block

TOP

Figure 13-71  Most cylinder head gaskets have markings to indicate proper installation direction.

10

4

2

6

8

7

5

1

3

9

Front

Figure 13-72  Typical cylinder head torque sequence.

SERVICE TIP  If locating dowels are not used, alignment pins can be made to assist in head installation. Thread a couple of locating pins in the corners of the deck surface. Slide the cylinder head gasket over the pins, and locate it on the deck surface. Next, slide the cylinder head over the pins and onto the gasket. Install the head bolts fingertight; then remove the alignment pins and install the correct bolts.

Caution Do not rotate the camshaft or crankshaft without the timing belt properly installed unless instructed to do so in the service manual.

VALVE TIMING AND INSTALLING VALVETRAIN COMPONENTS On OHV engines, the valve timing components can be installed after the camshaft and crankshaft. On OHC engines, these components are installed after the cylinder head and the valvetrain components. Regardless of the type of engine, it is important to install the valve timing components properly and to index them properly. Valve timing is usually done by aligning index marks. This procedure was discussed in Chapter 11 of this manual. If a balance shaft is used, it will also have timing marks, and it must be properly indexed.

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When installing the valve timing components, be sure that all idler and tensioner ­pulleys are free to rotate. In addition, the water pump may be driven from the timing belt, requiring installation before the timing belt. On many OHC engines, the valvetrain components can be installed before the ­cylinder head. If they are already installed, pour clean engine oil over them.

OHV Valvetrain Installation After the timing chain or belt is properly installed, the timing chain cover is installed next. Apply a small bead of sealant around the outer diameter of the timing cover seal, and install it with the lip facing toward the engine block. Lubricate the lip of the seal with engine oil. Locate the timing cover gasket onto the engine block, or place a bead of liquid gasket maker onto the block. Install the timing cover on the engine block. Torque the fasteners to the specified value. SERVICE TIP  On some engines, the water pump can be installed onto the timing cover before the cover is installed.

If the water pump is located outside the timing cover, it is installed next. Begin by placing the water pump gasket(s) onto the engine block, using adhesive if necessary. Install the bypass hose onto the nipple of the water pump. Place the hose clamps over the hose. Position the water pump to the engine block while installing the bypass hose to the block nipple. Torque the fasteners to the specified valve. Tighten the hose clamps. The remaining valvetrain components are installed next. Following is a typical ­procedure used on most OHV engines:

1. Dip the lifters into clean engine oil. 2. Install the lifters into their bores. 3. When properly installed, the lifters should rest on the camshaft lobes. 4. Rotate each lifter to be sure it is not bound in the bore. 5. Lubricate the pushrods with engine oil or assembly lube. 6. Install the pushrods, making sure they seat properly in the lifters. 7. If oil baffles or pushrod guides are used, install them. 8. Place the rocker arms or shaft assemblies over the pushrods, making sure that the ­pushrods seat properly in the rocker arms. 9. If the rocker arms are nonadjustable, torque the attaching bolts to the specified torque.

Caution If the original lifters are being reused, they must be ­reinstalled in their original positions on the camshaft.

Caution If the original ­followers and lash adjusters are being reused, they must be reinstalled in their original positions on the camshaft.

OHC Engine Valvetrain Following is a typical procedure for installing valvetrain components on OHC engines:

1. Dip the lash adjusters into clean engine oil. 2. Install the lash adjusters into their bores. 3. Rotate each lash adjuster to make sure it is not bound in the bore. 4. Place the followers over the lash adjusters. Make sure the valve stem is properly seated. 5. Install the camshaft. If caps are used, torque them to proper values. 6. Install the camshaft sprockets, aligning the keyway, and torque the fastener. It may be necessary to install the rear portion of the front cover before installing the sprockets. 7. Pour engine oil over the valvetrain assembly. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13 Cam sprocket timing marks

TDC mark Inspection hole

Pointer on lower cover Crankshaft TDC mark

Flywheel

Pointer on block

Figure 13-73  Timing belt installation on an OHC engine.

Figure 13-74  Some engines have timing marks on the flywheel.

Most OHC engines run the water pump from the timing belt, requiring it to be installed before the belt. Use adhesive to locate the gaskets onto the engine block. Place the water pump over the gasket, and torque the fasteners to the specified value. The timing belt is usually installed next (Figure 13-73); however, on some engines, it may be necessary to install the flexplate or flywheel before setting valve timing. This will be necessary if the ignition timing marks are located on the flexplate or flywheel (Figure 13-74). When installing the flexplate or flywheel, align the scribe marks made for reference during disassembly. Install the valve timing components and set valve timing using the procedures ­discussed in Chapter 11.

CHECKING AND ADJUSTING VALVE CLEARANCE After the valvetrain components are installed and the valves are properly timed, valve clearance should be checked (and in some instances adjusted). Refer to “Valve Adjustment” in Chapter 10 for more details. Valve clearance is easier to adjust on V-type engines when the intake manifold is still off. This is because lifters and pushrod positions can be seen. The correct hydraulic lifter adjustment is obtained by removing the lash between the lifter and the pushrod, and then depressing the pushrod a specified distance into the lifter. SERVICE TIP  If the service manual specifies a hot specification but does not provide a cold specification, make a slightly tighter (0.002 inch or 0.05 mm) initial cold setting. After the engine is warmed, readjust the valves using the hot specification.

COMPLETING THE ENGINE ASSEMBLY Completion of the assembly process requires the installation of such items as the oil pan, harmonic balancer, manifolds, valve covers, flywheel, fuel pump, and various accessories. Inspect the crankshaft vibration damper for wear on the sides of the pulley grooves. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Replace the vibration damper if there is wear in this area. Be sure the key, and keyways, in the crankshaft and vibration damper are not worn. Check for scoring on the seal contact area on the vibration damper. Replace the vibration damper if scoring or wear is present in this area. Some vibration dampers may be machined to a smaller size, and a sleeve may be pressed over the seal contact area. If the rubber ring in the vibration damper is cracked, oil soaked, or deteriorated, replace the damper. The vibration damper should also be replaced if the outer ring has slipped on the rubber ring, because this places the timing mark in the wrong position if this mark is located on the outer ring.

SERVICE TIP  Adjusting zero lash between the lift and pushrod can be done with the intake manifold installed by rotating the pushrod as the adjustment is made. When the pushrod no longer rotates, the lash is removed.

Inspect the oil pan flanges for a bent condition and metal stretching around the bolt holes. Bent flanges or stretched metal around the bolt hole may be corrected with a hammer and a block of wood. Be sure that all old gasket material is cleaned from the mating surfaces on the oil pan, valve covers, water pump, and manifolds. Following is a guide for completing the engine assembly: 1. Install the oil pan and gasket, and torque the fasteners to the specified value (Figure 13-75). Use sealant only if specified by the manufacturer (Figure 13-76). 2. Coat the crankshaft vibration damper sealing surface with engine oil, and apply sealer to the keyway. 3. Install the damper onto the front of the crankshaft. A special tool may be required to press the damper onto the crankshaft. 4. Torque the fastener to specifications. 5. Install the lower pulley to the vibration damper. 6. Install the water pump pulley (if equipped), and tighten the fasteners to specifications (Figure 13-77). The intake manifold is installed next (Figure 13-78). It is usually easier to adjust the valves before installing the intake manifold on V-type engines. If valve clearance has not been set, set it at this time. First check for proper fit of the intake manifold gasket

Apply liquid gasket here

Oil pan gasket

Oil pan

Figure 13-75  Oil pan and gasket.

Figure 13-76  This oil pan gasket is installed without any additional sealant.

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Chapter 13 3 1

5 6

4

2

8

7

Pulley Bolt

Water pump

Intake manifold

Timing cover

Front cover gasket

Cylinder block

Figure 13-77  Water pump, pulley, and timing cover installation.

Caution Do not install the damper by striking it with a hammer. The damper or crankshaft may be damaged.

Figure 13-78  Intake manifold and typical torque sequence.

(Figure 13-79). Most gaskets are marked to indicate proper direction for installation. After testing the fit, remove the intake gasket. Apply sealer at any locations directed in the service manual. On V-type engines, the four intersection points of the cylinder heads and the engine block usually require sealer. On V-type engines, locate the front and rear end seals onto the block. In addition, the intake manifold gasket may have alignment tabs that must fit into the head gasket for proper installation (Figure 13-80). The studs will hold the gasket in place while the manifold is installed on most in-line engines. On V-type engines, the gasket may slip as the manifold is lowered into place. To prevent this, use an adhesive to hold the gasket in place. Carefully lower the manifold into position. Then install the fasteners and torque to specifications. WARNING  If the cylinder heads on a V-type engine have been machined, the intake manifold must be machined accordingly so. Failure to machine the intake manifold before reassembly may cause oil and coolant leaks or consumption as well as reduced performance. Refer to Chapter 9 for more information.

On fuel-injected engines, install the fuel rail and the intake plenum and gasket. Torque the fasteners to the specified value. Next, install the throttle body assembly (Figure 13-81). Make sure to replace the high-pressure (2,000 psi) fuel lines when installing the ­camshaft-driven high-pressure pump onto the cylinder head of GDI (gasoline direct ­injection) systems. Next, install the exhaust manifold and gasket. Replace all mounting hardware used with the exhaust manifold. The old fasteners may have been weakened as a result of the Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Flange gasket

Alignment tabs

Rear intake manifold seal

Intake manifold gasket

Silicon rubber sealer applied at each end of seal Front intake manifold seal Cylinder head gasket

Figure 13-79  Installation of the intake manifold gasket.

Figure 13-80  Some intake gaskets must be indexed to the head gasket.

Intake manifold

Throttle body assembly Throttle body gasket

Figure 13-81  A typical throttle body installation. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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extreme temperatures. When installing oxygen sensors into the exhaust manifold, use an approved antiseize compound on the threads. Be sure to install all original heat shields and brackets onto the exhaust system. SERVICE TIP  Staking the engine block where the end strip gaskets are installed with a center punch will cause small bits of metal to be raised. This raised metal will catch and hold the strips in place while the intake manifold is being installed.

Some technicians prefer to leave the valve covers off until after the engine has been preoiled so they can see if oil is reaching the upper engine and to assist in still timing of the engine. Whenever the covers are installed, the following procedures apply:

Caution The fasteners used to secure the intake manifold must be properly torqued to prevent vacuum leaks. Use the ­tightening sequence and procedure ­recommended in the service manual.

1. Before installing a stamped steel cover, use a ball-peen hammer and a block of wood to remove deformities in and around the bolt holes. 2. If a plastic or cast aluminum cover is used, it must be replaced if it is distorted. 3. Torque the valve cover attaching fasteners, using the manufacturer’s specified torque (Figure 13-82). If no pattern to reference is available, use a cross pattern to prevent warpage to the cover. Overtightening the valve covers can result in oil ­leakage and can possibly crack the cover. 4. Always follow the manufacturer’s torque specification value and sequence when tightening. Overtightening the cylinder head (valve) covers can cause leakage from an unevenly pressed gasket. It may also bend or crack the cover. Installation of the flexplate or flywheel is next. Inspect the flywheel and crankshaft flange mating areas for metal burrs. Remove any metal burrs with a fine-toothed file. Metal burrs in this area cause excessive flywheel runout and improper clutch or transmission operation such as a grabbing clutch. Inspect the flywheel ring gear for worn teeth

Figure 13-82  Torque the valve covers; a careless installation could cause an oil leak and an unhappy customer. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Dial indicator

Dial indicator stylus should contact the flywheel approximately 1 inch from the edge.

Hold the flywheel and crankshaft forward or backward while checking runout.

Engine block

Figure 13-83  Using a dial indicator to measure flywheel runout.

and cracks. Worn ring gear teeth result in improper starting motor engagement. If these teeth are worn or the ring gear is cracked, ring gear replacement is necessary. Use the alignment marks inscribed during disassembly to properly index the flywheel to the crankshaft. Many manufacturers offset the bolt hole pattern so the flywheel can be installed in one position only. With the bolts properly torqued, use a dial indicator to check flywheel runout (Figure 13-83). Check runout by holding the crankshaft as far forward or rearward as it will go so end play is not indicated. Set the dial to read zero; then turn the ­flywheel one complete revolution while observing the dial indicator gauge. The TIR must be within specifications. If it is not, the flywheel may need to be resurfaced or replaced; however, before condemning the flywheel, remove it from the crankshaft flange and install the dial indicator to check flange runout. Also make sure there are no burrs on the mounting flange or the mounting surface of the flywheel. Install all accessory items that attach to the block. These may include the following: ■■ The accessory drive belts, generator, power steering pump, air injection reaction (AIR) pump, air-conditioning compressor, and water pump ■■ Ignition coil and spark plugs, exhaust gas recirculation (EGR) assembly, thermostat housing, and thermostat ■■ All electrical sensors and switches (Figure 13-84) ■■ Engine mounts

Special Tools Dial indicator

Caution Overtightening the oil filter may cause seal damage and result in oil leakage.

SERVICE TIP  It may be easier on some engines to leave the spark plugs and distributor out until the engine is installed into the vehicle. Leaving the spark plugs out will make it easier to rotate the engine if needed.

To complete the assembly, lubricate the oil filter gasket and fill the filter with oil. Install the oil filter. Do not overtighten the filter. Turn the filter three-quarter turn after the seal makes contact. With the engine fully assembled, double-check your work before installation (Figure 13-85). Follow the installation and break-in procedures provided in Chapter 8 of the Shop Manual to ensure that your hard work is fully successful. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13 EVAP purge control solenoid

Throttle position sensor Intake air temperature sensor

Engine coolant sensor

Idle air control (IAC) Manifold absolute pressure sensor

PCV valve

Power steering pressure switch

Ignition control module (ICM)

Top dead center/crankshaft position/cylinder position (TDC/CKP/CYP) sensor Knock sensor

Heated oxygen sensor (HO2S)

Figure 13-84  Modern vehicles have several sensors and switches mounted on the engine assembly.

Figure 13-85  The technician double-checked her work, repainted the old components, and is anxious to hear her freshly built engine run.

CUSTOMER CARE  Before the customer picks up the vehicle, have it cleaned and completely inspected. Correct any problems that are found, even if they are not associated with your repairs. This will lead to higher customer satisfaction.

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CUSTOMER CARE  A few days after the customer picks up the vehicle, call her to make sure everything is to her satisfaction. Ask the customer how many miles are on the new engine, and schedule the 500-mile follow-up service. To prevent the customer from having to spend additional money at the time of the follow-up service, do not charge for this service separately. Include the cost of the 500-mile service in the cost of the engine rebuild.

CASE STUDY Many hours of labor have been put into the rebuilding of the customer’s engine. The technician’s reputation is on the line with every job performed. Taking pride in a job well done is a big step toward building a good reputation. The technician has seen his efforts restore a worn engine into a new power plant. Now he is ready for the moment of truth. The engine has been installed; everything has been double-checked. The key is turned over and the engine roars to life. Before turning the vehicle back over to the owner, the technician takes a few extra moments to clean the vehicle and reset the radio. A few days later he calls the customer to confirm all is right and remind her of the scheduled service.

ASE-STYLE REVIEW QUESTIONS 1. The main bearings indicate wear on the lower inserts on all journals. Technician A says that this indicates lack of oil. Technician B says that this indicates excessive idling. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

4. Technician A says that a bend in a connecting rod may not be noticeable during a visual inspection. Technician B says that a misaligned connecting rod will produce diagonal scuffing on the piston. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

2. While discussing the removal of press-fit piston pins, Technician A says that the pin can be carefully driven out with a punch and hammer while securing the piston in a vise. Technician B says that removing the pin requires a press and special adaptors. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

5. The camshaft bearings are being installed in the block of an OHV engine. Technician A says that the camshaft bearings may have some minor high spots from the installation process. Technician B says that the camshaft bearings ­usually require a special tool to install them because they are press fit. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. While discussing piston ring end gap, Technician A says that an end gap that is too wide can result in scuffing. Technician B says that an end gap that is too ­narrow can allow blowby. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. Technician A says that excessive camshaft end play may cause timing chain noise. Technician B says that camshaft end play is checked using a feeler gauge. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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7. While discussing main bearing installation, Technician A says that many manufacturers use a select fit bearing selection procedure. Technician B says that most manufacturers ­identify the use of select bearings by codes on the engine block and the crankshaft. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. Technician A says that plastigage strips should be placed lengthwise on the journal. Technician B says that plastigage measures total ­bearing clearance. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

9. Technician A says that most piston assemblies are nondirectional. Technician B says that the notch on the piston head usually faces toward the front of the engine block. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. If a harmonic balancer outer ring has slipped on the rubber mounting, the technician should. A. twist the outer ring back to the original position. B. secure the outer ring by welding it in place. C. replace the harmonic balancer. D. press on a new outer ring.

ASE CHALLENGE QUESTIONS 1. If pistons are installed without removing the ring ridge, the following may result: A. The piston skirt may be damaged. B. The piston pin may be broken. C. The connecting rod bearings may be damaged. D. The piston rings may be broken. 2. A bent connecting rod may cause. A. uneven connecting rod bearing wear. B. uneven main bearing wear. C. uneven piston pin wear. D. excessive cylinder wall wear.

4. A piston that is installed backward will. A. break the connecting rod. B. wear out the rod bearings quickly. C. cause piston slap. D. break the piston. 5. A worn pilot bearing may cause a growling, ­rattling noise. A. while driving at a steady speed of 50 mph (80 km/h). B. in reverse with the clutch engaged. C. while accelerating in second gear. D. with the clutch disengaged.

3. While discussing piston ring service, Technician A says that the ring end gap should be measured with the ring just below the ring ridge. Technician B says to position the ring at the ­bottom of ring travel to measure the end gap. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

639

JOB SHEET

80

INSPECTING THE PISTONS AND CONNECTING RODS Upon completion of this job sheet you should be able to properly inspect pistons, connecting rods, and piston pins. You should also be able to remove a piston from a connecting rod. NATEF Correlation This job sheet addresses the following MAST tasks for Engine Repair: C.9. Identify piston and bearing wear patterns that indicate connecting rod alignment and main bearing bore problems; determine necessary action. C.10.

Inspect and measure piston skirts and ring lands; determine necessary action.

C.12.

Inspect, measure, and install piston rings.

Tools and Materials • Micrometer • Vise • Press • Piston pin press tools • Connecting rod vice Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific engine. Write down the information, and then perform the following tasks: 1. Line up the pistons and connecting rods in order on a clean bench.

h

2. Visually inspect each connecting rod for damage, bend, cracks, and nicks. Record your results. Piston no. 1 _______________________________________________________________ Piston no. 2 _______________________________________________________________ Piston no. 3 _______________________________________________________________ Piston no. 4 _______________________________________________________________ Piston no. 5 _______________________________________________________________ Piston no. 6 _______________________________________________________________ Piston no. 7 _______________________________________________________________ Piston no. 8 _______________________________________________________________ 3. Remove the rod bearings, and keep them in order for later inspection.

h

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4. Clean the big-end bore; note any visible issues, and measure the diameter and for out-of-round. Record your results.

Task Completed

Rod no. 1 _________________________________________________________________ Rod no. 2 _________________________________________________________________ Rod no. 3 _________________________________________________________________ Rod no. 4 _________________________________________________________________ Rod no. 5 _________________________________________________________________ Rod no. 6 _________________________________________________________________ Rod no. 7 _________________________________________________________________ Rod no. 8 _________________________________________________________________ 5. Remove the piston rings using a ring expander, and be careful not to scrape the sides of the pistons. Lay to the side for later inspection. Clean the ring grooves using a ring groove cleaner.

h

6. Visually inspect the piston ring grooves, ring lands, piston heads, and piston skirts for excessive scuffing. Record your results. Piston no. 1 _______________________________________________________________ Piston no. 2 _______________________________________________________________ Piston no. 3 _______________________________________________________________ Piston no. 4 _______________________________________________________________ Piston no. 5 _______________________________________________________________ Piston no. 6 _______________________________________________________________ Piston no. 7 _______________________________________________________________ Piston no. 8 _______________________________________________________________ 7. Locate the manufacturer’s service information for where to measure piston diameter. Describe that procedure. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Measure the piston diameter and compare it to specifications. Record your results. Piston no. 1 diameter _______________ Within specification?  h Yes  h No Piston no. 2 diameter _______________ Within specification?  h Yes  h No Piston no. 3 diameter _______________ Within specification?  h Yes  h No Piston no. 4 diameter _______________ Within specification?  h Yes  h No

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Task Completed Piston no. 5 diameter _______________ Within specification?  h Yes  h No Piston no. 6 diameter _______________ Within specification?  h Yes  h No Piston no. 7 diameter _______________ Within specification?  h Yes  h No Piston no. 8 diameter _______________ Within specification?  h Yes  h No 9. Hold one piston assembly, and feel for free movement of the connecting rod. Place a shop rag around the connecting rod, and place it in a vise. Push up and down on the piston to feel for even the slightest vertical movement. It should move sideways freely. Repeat for each piston and rod assembly. Record your results. Piston no. 1 _______________________________________________________________ Piston no. 2 _______________________________________________________________ Piston no. 3 _______________________________________________________________ Piston no. 4 _______________________________________________________________ Piston no. 5 _______________________________________________________________ Piston no. 6 _______________________________________________________________ Piston no. 7 _______________________________________________________________ Piston no. 8 _______________________________________________________________ 10. If any pistons felt loose on the rod and your shop has the proper press and piston pin adaptor, remove those pistons from the rod. Does your shop have the proper equipment to remove the piston?

h Yes  h No

11. If your shop does not have the proper equipment, have your instructor check your work now.

h

12. If you have the equipment, note or mark the orientation of the piston on the rod. Set the piston and pin press adaptor on the vise. Be certain the piston and press rod are aligned properly. You must have safety glasses on. Press the pin from the piston and the connecting rod. Repeat for as many piston assemblies as required. If the piston pins are full floating, simply remove the snap rings and push the pins out. Did you successfully remove the pin(s)?

h Yes  h No

13. Set the piston and the connecting rod aside. Visually inspect the piston pin for wear and measure its diameter. Record your results. Pin no. 1 visual condition and diameter. _______________________________________ Pin no. 2 visual condition and diameter. _______________________________________ Pin no. 3 visual condition and diameter. _______________________________________ Pin no. 4 visual condition and diameter. _______________________________________ Pin no. 5 visual condition and diameter. _______________________________________ Pin no. 6 visual condition and diameter. _______________________________________ Pin no. 7 visual condition and diameter. _______________________________________ Pin no. 8 visual condition and diameter. _______________________________________

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14. Compare the pins to specification. Which, if any, are worn? _________________________________________________________________________ _________________________________________________________________________ 15. Inspect the connecting rod and the piston bore for signs of wear. Measure the connecting rod bore using an inside micrometer or a dial bore gauge. Compare the bore to specifications. (On some piston assemblies, it will also be necessary to measure the bore in the piston; perform the work as specified in the service information.) Record your results. Bore no. 1 diameter _______________ Within specifications?  h Yes  h No Bore no. 2 diameter _______________ Within specifications?  h Yes  h No Bore no. 3 diameter _______________ Within specifications?  h Yes  h No Bore no. 4 diameter _______________ Within specifications?  h Yes  h No Bore no. 5 diameter _______________ Within specifications?  h Yes  h No Bore no. 6 diameter _______________ Within specifications?  h Yes  h No Bore no. 7 diameter _______________ Within specifications?  h Yes  h No Bore no. 8 diameter _______________ Within specifications?  h Yes  h No 16. Describe any work necessary to repair improper piston to rod fit. Record your results. Piston no. 1 _______________________________________________________________ Piston no. 2 _______________________________________________________________ Piston no. 3 _______________________________________________________________ Piston no. 4 _______________________________________________________________ Piston no. 5 _______________________________________________________________ Piston no. 6 _______________________________________________________________ Piston no. 7 _______________________________________________________________ Piston no. 8 _______________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

643

JOB SHEET

81

INSPECTING THE BEARING WEAR PATTERNS Upon completion of this job sheet, you should be able to inspect main and connecting rod bearings and determine problems indicated by unusual wear patterns. NATEF Correlation This job sheet addresses the following MAST tasks for Engine Repair: C.8. Inspect main and connecting rod bearings for damage and wear; determine necessary action. C.9. Identify piston and bearing wear patterns that indicate connecting rod alignment and main bearing bore problems; determine necessary action. Tools and Materials • Dial bore gauge • Straightedge • Feeler gauges Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific engine. Write down the information, and then perform the following tasks: 1. Lay the main bearing halves out with main number 1 bottom half below main number 1 top half. Line up the rest in order in the same fashion. Describe the visual wear on the front and back of each bearing. Record your results. Bearing no. 1 bottom _______________________________________________________ Bearing no. 1 top ___________________________________________________________ Bearing no. 2 bottom _______________________________________________________ Bearing no. 2 top ___________________________________________________________ Bearing no. 3 bottom _______________________________________________________ Bearing no. 3 top ___________________________________________________________ Bearing no. 4 bottom _______________________________________________________ Bearing no. 4 top ___________________________________________________________ Bearing no. 5 bottom _______________________________________________________ Bearing no. 5 top ___________________________________________________________ Bearing no. 6 bottom _______________________________________________________ Bearing no. 6 top ___________________________________________________________ Bearing no. 7 bottom _______________________________________________________ Bearing no. 7 top ___________________________________________________________ Bearing no. 8 bottom _______________________________________________________ Bearing no. 8 top ___________________________________________________________

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Chapter 13

Task Completed 2. Is the bearing wear uneven around the bearing halves?   h Yes  h No Does the pattern of bearing wear indicate the possibility of main bearing bore h Yes  h No misalignment? 3. If main bearing bore misalignment is a possibility, check it now. Torque the main caps on in the proper sequence to the proper specification.

h

Look up the specification for the maximum allowable main bore misalignment. Record your results. ________________________________________________________ Lay a straightedge in the top and bottom of the bearing bores, and try to fit a feeler gauge the size of the allowable misalignment under the straightedge in each cap. Does the feeler gauge fit anywhere?   h Yes  h No If the misalignment is too great, describe the procedure to fix the problem. _________________________________________________________________________ 4. Do your bearings show any concentrated wear on the sides, indicating that a bearing cap was misaligned?   h Yes  h No 5. Are your bearings smeared, indicating improper or inadequate lubrication, or dirt behind the bearing back?   h Yes  h No 6. Are any of your bearing backs scored or polished, indicating that they may have spun in their bore?   h Yes  h No 7. Do any of your connecting rod bearings indicate wear on the opposite sides of the upper and lower bearing, indicating a bent connecting rod?   h Yes  h No 8. Describe your overall assessment of the main and rod bearings in your engine and what corrective actions you will have to take before reassembling your engine. Main bearing indications: _________________________________________________________________________ _________________________________________________________________________ Rod bearing indications: _________________________________________________________________________ _________________________________________________________________________ Corrective actions: _________________________________________________________________________ _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

645

JOB SHEET

82

INSTALLING THE PISTON RINGS Upon completion of this job sheet, you should be able to properly install the piston rings. NATEF Correlation This job sheet addresses the following MAST task for Engine Repair: C.12.

Inspect, measure, and install piston rings.

Tools and Materials • Ring expander • Feeler gauges Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific engine. Write down the information, and then perform the following tasks: 1. Locate the correct rings for your engine. Look up the correct installation of the ring gaps, and draw a diagram showing it below:

2. Look up the specification for ring side clearance and for ring end gap. Record your results. Ring side clearance specification: _____________________________________________ Ring end gap specification: __________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

3. Place an oil ring in the cylinder where indicated by the service information or toward the bottom of ring travel, and square it with a piston. Measure the end gap. Place the second ring in the cylinder and measure the end gap. Place the top ring in the cylinder and measure the end gap. Repeat for all cylinders. Record your results. Cyl. no. 1: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 2: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 3: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 4: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 5: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 6: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 7: oil gap ______________ Second gap ______________ Top gap _____________ Cyl. no. 8: oil gap ______________ Second gap ______________ Top gap _____________ 4. Are any gaps too wide? h Yes h No What, if anything, will you do to correct this? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Are any gaps too narrow? h Yes h No What, if anything, will you do to correct this? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Lubricate piston number 1. Install the oil ring, expander, and second oil ring by hand, being careful not to twist them excessively. Use a ring expander to properly install the second ring. Is there a top marking?   h Yes h No Use a ring expander to properly install the top ring. Is there a top marking? h Yes h No Repeat for all pistons. 6. Measure ring side clearance for the oil, second, and top rings as specified. Repeat for each piston. Record your results. Piston no. 1: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 2: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 3: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 4: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 5: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 6: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 7: oil clearance ________ Second clearance ________ Top clearance ________ Piston no. 8: oil clearance ________ Second clearance ________ Top clearance ________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Task Completed 7. Space the gaps as instructed on each piston.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

647

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

649

JOB SHEET

83

INSTALLING THE CAMSHAFT Upon completion of this job sheet, you should be able to install the camshaft into the engine block (OHV engine) or the cylinder head (OHC engine) properly. NATEF Correlation This job sheet addresses the following AST/MAST tasks for Engine Repair: B.5. Inspect and replace camshaft and drive belt/chain; includes checking drive gear wear and backlash, end play, sprocket and chain wear, overhead cam drive sprocket(s), drive belt(s), belt tension, tensioners, camshaft reluctor ring/­ tone-wheel, and valve timing components; verify correct camshaft timing. B.6.

Establish camshaft position sensor indexing.

Tools and Materials • Dial indicator • Micrometer • Inside micrometer • Telescoping gauge • Engine block Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Task Completed

Procedure Using the engine block or cylinder head from the engine you have disassembled and the proper service manual, you will identify and perform the required steps to install the camshaft. 1. What are the specifications for oil clearance of the camshaft bearings? _________________________________________________________________________ 2. Measure the oil clearance between the installed camshaft bearings and the camshaft journals, and record your results in the following chart. Bore Number

Clearance

1

_______________

2

_______________

3

_______________

4

_______________

5

_______________

3. Place an * (or more than one, if necessary) in the previous chart to indicate any clearances that are out of specification. If any bearing clearances are excessive, consult your instructor. 4. Use a rag soaked in solvent to remove any coating on the camshaft journals. Be careful not to remove the coating on the lobes.

h

5. Lubricate the journals with engine oil or assembly lube.

h

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Task Completed 6. Install the camshaft, preventing any contact between the lobes and the bearings.

h

7. Spin the camshaft to ensure free rotation. Does the camshaft spin freely? h Yes h No If No, inspect the camshaft bearings for high spots, and remove using a threecornered scraper. If the bearings are not the cause of the binding, the camshaft may be bent. 8. What is the specification for the depth of the rear camshaft core plug? 9. Apply sealer to the outer edge of the rear core plug, and install the plug in the correct direction and to the correct depth. Which way does the plug face?

Caution Do not use emery cloth to remove high spots. The grit can embed into the ­bearing surfaces and damage the journals.

10. After the core plug is installed, rotate the camshaft to ensure the plug is not causing interference.

h

11. Install the camshaft retainer plate.

h

12. What is the specification for camshaft end play? __________________________________ 13. Measure camshaft end play. ____________________________________________________ 14. If the camshaft end play is out of specification, how can it be corrected? 15. Apply special camshaft break-in high-pressure lubricant onto the lobes, being careful not to get any on the journals.

h

16. If a camshaft sensor is used, install it using the manufacture’s service directions for installation and indexing. If the engine you are working on has a camshaft sensor, describe how it was installed and indexed. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

651

JOB SHEET

84

INSTALLING THE MAIN BEARINGS AND THE CRANKSHAFT Upon completion of this job sheet, you should be able to install the main bearings and the crankshaft into the engine block properly. Tools and Materials • Dial indicator • Plastigauge clearance indicator gauge (Plastigage) • Torque wrench • Engine block Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Using the engine block and crankshaft from the engine you have disassembled and the proper service manual, you will identify and perform the required steps to install the main bearings and the crankshaft. 1. Replace the pilot bushing or bearing installed in the end of crankshaft (used with manual transmissions).

h

2. Make sure the proper main bearings are selected for the engine. Does this engine use select bearings? h Yes h No If Yes, how are they identified? _________________________________________________________________________ 3. Clean the block saddles, caps, and bearings thoroughly.

h

4. Install all upper bearing inserts into the block. These inserts will have oil holes and grooves that must be properly aligned with the block. Make sure to install the thrust washer into the specified saddle. Which bore is the thrust bearing installed in? _________________________________________________________________________ 5. Install the lower bearing inserts into the caps.

h

6. Inspect the cap bolts for damage.

h

7. What is the specification for main bearing oil clearance? _________________________________________________________________________ 8. Is the specification for actual or total oil clearance?

h

9. What method of measuring oil clearance is recommended by the service manual? _________________________________________________________________________ 10. If using plastigage, install the crankshaft into the saddles. When installing the crankshaft, lift it by the harmonic balancer journal and by bolts threaded into the rear flange. As the crankshaft is lowered into the bearings, keep it parallel to the bearings, and lower it straight down. If installed properly, the crankshaft will seat square and be supported by the bearings.

h

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Task Completed 11. Measure the oil clearance of each main bearing, and record your results in the following chart. Bore Number

Clearance

1

_______________

2

_______________

3

_______________

4

_______________

5

_______________

12. Place an * (or more than one, if necessary) in the previous chart to indicate any oil clearances that are out of specification. If any clearances are out of specification, what procedure can be used to correct them? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 13. Correct any oil clearances to specifications as needed.

h

14. If the rear main seal is a two-piece lip seal, install the pieces into the block and rear cap. Which direction must the lip of the seal face? _________________________________________________________________________ 15. Lubricate the inside surfaces of the bearing inserts with a film of engine oil.

h

16. Install the crankshaft, caps, and bolts. Apply anaerobic sealer between the rear cap and the cylinder block (if needed).

h

17. Place the main bearing caps over the crankshaft journals, starting at the rear journal and working toward the front of the engine, making sure that the correct cap is installed in the correct location and in the proper direction.

h

18. Register the main bearing caps by tightening the cap bolts by hand while rotating the crankshaft.

h

19. With the main bearing cap bolts fingertight, pry the crankshaft back and forth to align the thrust bearing.

h

20. Rotate the crankshaft. Does it rotate freely with no binding or restrictions? h Yes h No If No, correct any problems before continuing. 21. What is the torque specification for the main bearing cap bolts? _________________________________________________________________________ 22. In the space below, draw the torque sequence for the main bearing cap bolts. 23. Torque the bolts of the first cap in sequence to the specified value.

h

24. Check crankshaft rotation by rotating it with a torque wrench. Note the amount of torque required to rotate the crankshaft during several revolutions. _________________________________________________________________________ Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Task Completed 25. Torque the next cap in the sequence, and check the rotating torque of the crankshaft again.

h

26. Continue to torque the cap bolts in sequence, making sure to check rotating torque after each cap is tightened. Record the turning torque of the crankshaft for the remaining caps. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 27. Were there any large increases in the torque required to rotate the crankshaft? h Yes h No If Yes, stop and locate the cause of the problem. 28. With all cap bolts properly torqued, check the rotating torque of the crankshaft. Specification _______________ Actual _______________ 29. If the engine uses a one-piece lip seal, install it.

h

30. Check crankshaft end play. Specification _______________ Actual _______________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

653

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

Name ______________________________________

Date __________________

655

JOB SHEET

85

INSTALLING THE PISTONS AND THE CONNECTING RODS Upon completion of this job sheet, you should be able to properly install the piston assemblies into the engine block. Tools and Materials • Ring compressor • Torque wrench • Feeler gauge • Engine block Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Using the engine block and piston assemblies from the engine you have disassembled and the proper service manual, you will identify and perform the required steps to install the piston assemblies into the block. 1. Is there a difference between the bearing inserts that fit into the connecting rod and the inserts that fit into the cap? h Yes  h No If Yes, describe which ones fit the rod and which ones fit the cap. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. Install the bearing inserts into the connecting rods and the caps, making sure that the oil holes align and the tabs are properly located.

h

3. Coat the cylinder walls with clean engine oil, and soak the piston head in a container of clean engine oil. If bearing clearance is being measured using plastigage, oil cannot be applied to the bearings.

h

4. Rotate the crankshaft so that the connecting-rod journal for the piston assembly being installed is at BDC.

h

5. Ensure that the piston assemblies are in the proper order and the correct caps are with the correct rods.

h

6. Cover the connecting rod bolts with a special guide or pieces of rubber hose to protect the cylinder walls and crankshaft-rod journals from damage.

h

7. Use a ring compressor to squeeze the rings together.

h

8. Install the piston assembly into the correct bore. Double-check to ensure that the correct piston is being installed into its corresponding bore and it faces the correct direction. The pistons should go into the bore with a slight restriction. Using a hammer handle to tap the piston assembly into the cylinder will make installation easier.

h

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Chapter 13

Task Completed 9. As each connecting rod is installed onto the crankshaft, tighten the cap bolts only fingertight. Check the rotating torque of the crankshaft as each piston is installed. This gives an indication of the interference between the piston rings and the cylinder walls. If any of the pistons causes a large increase in turning torque, repair the cause before continuing.

h

10. Starting with the first connecting rod in sequence, torque the cap bolts. As the bolts are torqued, tighten them in small increments, alternating back and forth between the two bolts.

h

11. As each piston assembly is installed, fill out the following chart: Rod cap bolt torque specification _______________ Connecting rod bearing oil clearance specification _______________ Actual oil clearance: Piston No.

Clearance

1

_______________

2

_______________

3

_______________

4

_______________

5

_______________

6

_______________

7

_______________

8

_______________

12. After all the pistons are installed, check the rotating torque and record it. _________________________________________________________________________ What is the specification? ___________________________________________________ If the actual turning torque is not within specifications, what must be corrected? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 13. When installing and torquing the cap bolts for the final assembly, coat the bolt threads with a thread locking compound.

h

14. What is the specification for connecting rod side clearance? _________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Short Block Component Service and Engine Assembly

15. Measure the side clearance for each connecting rod, and record your results in the following chart. Piston No.

Clearance

1

_______________

2

_______________

3

_______________

4

_______________

5

_______________

6

_______________

7

_______________

8

_______________

16. What is the minimum specification for deck clearance? _________________________________________________________________________ 17. Actual deck clearance: _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

657

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

CHAPTER 14

ALTERNATIVE FUEL AND ADVANCED TECHNOLOGY VEHICLE SERVICE

Upon completion and review of this chapter, you should understand and be able to describe: ■■

■■

How to shut off fuel on a propanefueled vehicle to perform engine ­maintenance and repair. How to shut off fuel on a compressed natural gas (CNG) vehicle to perform engine maintenance and repair.

■■

■■

The safety precautions necessary for working on hybrid electric vehicles (HEVs). The specific maintenance and service procedures for HEVs and alternative fuel vehicles.

Terms To Know Fuel control valve Lineman’s gloves Manual shut-off valve

INTRODUCTION Most of the base engines in all of the alternative fuel and advanced technology vehicles described in the classroom manual are serviced using the same techniques we have discussed in the previous chapters of this shop manual. What differs here is that there are fuels under extremely high pressures and voltages above safe levels. You must receive proper instruction to work on the engines of these vehicles. This chapter is intended to offer some basic safety precautions for work on these vehicles. This information is not a substitute for the manufacturer’s recommended procedures. You should always consult the service information for the vehicle you are working on before attempting engine repairs on an alternative fuel, HEV, or other advanced technology vehicle. Your basic knowledge of safety procedures such as always wearing appropriate safety glasses and clothing, using proper ventilation, and eliminating sources of ignition when working with fuel are still critical elements of safe vehicle service.

SERVICING PROPANE-FUELED ENGINES The engine of an liquefied petroleum gas (LPG) vehicle is nearly the same, if not identical to, that of a gas-powered vehicle. You can expect the engine wear to decrease with the use of propane, but still there will be occurrences of mechanical wear or failures within the engine. When these occur, you should evaluate the engine using the same tests—such as compression, noise analysis, and power balance—as you have learned for gasoline engines. If the vehicle has been converted, you can use the same specifications (such as compression, valve adjustment) as those listed for its gasoline counterpart. If ignition timing and Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

659

660

Chapter 14

Repair rate (repairs per 5,000 miles)

2.5

2.0

1.5

1.0

0.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Vehicle number Vehicle repair LPG-related repair

Figure 14-1  This chart shows that few of the required repairs to this fleet were related to the LPG system.

Figure 14-2  The LPG tanks hold fuel under high pressure.

fuel delivery is adjustable, those specifications will be modified and should be marked on an under-hood label or in an addition to the owner’s manual. As mentioned in the Classroom Manual, propane-fueled engines may last two to three times longer than the same engine run on gasoline. Spark plugs may also last significantly longer. But when problems arise, you should still check these basics before suspecting problems related to the LPG supply system. One fleet study showed that the vast majority of repairs were performed on the gas-powered vehicles rather than the propane-fueled vehicles (Figure 14-1). When performing tests on a running propane vehicle, there should be no unusual safety precautions. If you smell propane, shut the fuel supply off immediately. Locate and repair the source of the leak before proceeding with engine diagnosis. Cooling and lubrication system testing will be the same on an LPG engine as on a gasoline engine. Before performing mechanical repairs on a propane engine that require you to disable fuel or disconnect fuel fittings, you need to turn the propane supply off (Figure 14-2). Follow the manufacturer’s procedure to disable the propane fuel system. Run the vehicle until it stalls to remove the remaining fuel from the lines. With the propane vented from the lines and engine, you can safely work on the engine mechanical components as you would on any other vehicle.

SERVICING CNG VEHICLES

The fuel control valve is a manually operated valve designed to stop fuel flow from the cylinder.

Your primary consideration when performing mechanical repairs on a CNG vehicle is safety. CNG is stored at pressures between 3,000 psi and 3,600 psi. You should be a qualified CNG technician before performing repairs on the CNG system. Once you learn how to disable the fuel system, you should still be able to perform the engine diagnosis and repair procedures you have already learned. To disable the fuel system, locate the fuel control valve on the tank(s) and shut it off (Figure 14-3). Turn it fully clockwise to prevent fuel flow out of the cylinder. Now no fuel can flow from the tank. Next, start the vehicle, if possible, to purge the remaining fuel from the lines. You should attempt to start the vehicle three times, and once it starts, it will run out of fuel and shut off. Now the system is free of fuel. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicle Service

661

Fuel cylinder

Fuel gauge pressure sensor

Valve handle

Manual shut-off valve

Pressure relief safety device

Figure 14-3  Rotate the fuel control valve clockwise to stop fuel flow.

MANUAL SHUT-OFF VALVE CAUTION: HIGH PRESSURE

Figure 14-5  The manual shut-off valve will be labeled.

Vehicle frame

Figure 14-4  Locate the manual shut-off valve on the exterior of the vehicle.

Manual shut-off valve

Handle

Fuel line

Vehicle frame

Figure 14-6  Turn the quarter turn manual shut-off valve so it is perpendicular to the fuel line.

Finally, you should turn off the manual shut-off valve (Figure 14-4). It will be accessible from the exterior of the vehicle and highlighted with a label (Figure 14-5). Turn the quarter turn valve so that the handle is perpendicular to the fuel line (Figure 14-6). This stops fuel flow from this point forward to the engine. Even with the fuel system fully disabled, there are some precautions you should follow when working around a CNG vehicle (Figure 14-7). These include the following: ■■ Only qualified CNG technicians should service the CNG system. ■■ Natural gas is explosive. Do not use sources of ignition with natural gas vapors present. ■■ The work area should have adequate ventilation. ■■ Natural gas contains an odor additive. If a strong natural gas odor occurs, shut the fuel control valves off at the tank immediately. Ventilate the area to allow the gas to dissipate. Natural gas is lighter than air, so it will rise. This minimizes the risk of fire or explosion as long as there is adequate ventilation. If necessary, evacuate the area and contact emergency personnel. ■■ Do not undercoat or paint any fuel system line or component. ■■ Do not attempt to weld any fuel system component. ■■ Do not attempt to repair any fuel cylinder problems; they are serviced by replacement.

The manual shut-off valve stops fuel flow from the CNG cylinder(s) to the engine.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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CNG WARNING: DO NOT WORK ON OPEN GAS LINES OR FITTINGS WITHOUT MAKING CERTAIN ALL TANKS ARE COMPLETELY SHUT OFF.

CNG FUELED VEHICLE MODEL # SERIAL # VIN # INSTALLED BY SYSTEM WORKING PRESSURE

TOTAL CYLINDER WATER VOLUME CU. IN.:

HIGH PRESSURE NO WELDING OR CUTTING

LITERS:

CYLINDER RETEST DATE:

ALL CNG COMPONENTS MUST BE SERVICED BY AUTHORIZED MECHANICS ONLY.

CAUTION: HIGH PRESSURE

Figure 14-7  Typical CNG vehicle warning labels. ■■ ■■ ■■ ■■ ■■

■■

MANUAL SHUT-OFF VALVE

Figure 14-8  Most CNG refilling stations are protected and need ­special training to operate.

Do not modify fuel system components or replace them with parts of lesser quality than those provided by the manufacturer. When a vehicle is disabled for a period of time, turn off the fuel control valves at the tank and the manual shut-off valve. Do not attempt to fill a damaged cylinder. Whenever a CNG vehicle has been in an accident, inspect the CNG cylinders as specified by the manufacturer. This is a law in the United States and in Canada. CNG cylinders must be removed and inspected every three years. Repairs are not allowed. A label noting the date of inspection and expiration must be affixed to the tank and sealed with epoxy. CNG cylinders must be replaced every 15 years. SERVICE TIP  It is normal to smell some natural gas when starting and stopping the engine of a CNG vehicle. Use proper ventilation when running the vehicle in the shop.

CUSTOMER CARE  When working on a customer’s CNG vehicle, visually inspect the fuel system components for wear or damage. Locate the cylinder inspection label, and inform the customer when the next inspection is due.

With the fuel system properly disabled and the work area ventilated, you may begin work on the CNG engine. Follow the manufacturer’s procedures carefully to properly remove fuel system components for access to components such as water pumps, cylinder heads, or even for engine removal. The oil requirement may also be different for a CNG engine. Your study of this text and your work in the shop will qualify you to work on a CNG engine, just not the CNG fuel system. Remember to check manufacturer’s specifications, as dedicated CNG engines have been modified from gasoline engines. The compression values for the Civic CNG with a 12.5:1 compression ratio will be higher than those for the gasoline version. In order to refill the fuel tank on a CNG vehicle you must have specialized training (Figure 14-8). Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicle Service

SERVICING HYBRID ELECTRIC VEHICLES The service of HEVs is currently limited to technicians who have received factory training from the manufacturer. Manufacturers require that a dealership that sells an HEV model has at least one technician who has participated in factory training through an interactive training program and classroom and hands-on training. This text cannot train you to work on any current HEV. As a technician, you should be aware of the safety precautions of these vehicles. If you perform towing, you must be fully aware of the safety precautions before approaching a damaged HEV. These vehicles come with extended warranties, so it is likely that you will only see them in your service bay in the next few years if you are working at a dealership that sells them. Your education may well place you at the front of the line for training on these advanced technology vehicles. SERVICE TIP  Something as simple as a blown high-voltage fuse could cause a vehicle not to drive. You will still need to follow special safety precautions for testing them, though. They are rated between 400 and 600 amps!

Safety, as with CNG vehicles, must be your first consideration when approaching an HEV (Figure 14-9). The voltages on some HEVs may reach 500 volts and regularly store 360 volts. Voltage varies with make, but over 30 volts is potentially fatal to humans, so we are dealing with a potentially lethal mechanism. All high-voltage cables are identifiable by a bright orange coating. Never touch these wires while the electrical system is live. All high-voltage components are labeled as such (Figure 14-10). The battery packs are well insulated and protected in an accident. Nickel metal hydride (NiMH) batteries, as used in many of today’s HEVs, are sealed in packs designed not to leak even in the event of a crash. If they do leak, the electrolyte can be neutralized with a dilute boric acid solution or vinegar. Understanding proper operation of the vehicle you are working on is essential. Though you should have received factory training, much of this information can be found in the owner’s manual. The vehicle may be “ready” and able to move with a tap of the accelerator, even when neither the electric motor nor the gasoline engine is running. The owner’s manual will provide you with special operating characteristics of the vehicle and basic safety warnings.

Figure 14-9  Use caution! Look carefully at this warning label; it says “you will be killed” if you do not use appropriate safety precautions. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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High-voltage cables

Figure 14-10  The brightly colored big cables hold high voltage; components that use high voltage have warning labels.

CUSTOMER CARE  It is not uncommon for a customer with a new technology vehicle to come in with service questions. Most consumers do not take the time to read the owner’s manual or view the operational CD provided. When you are working on a make of vehicle, be as familiar with it as possible so you can competently answer questions a customer might have about his new vehicle.

Special Tools Lineman’s gloves

SERVICING THE TOYOTA PRIUS First, familiarize yourself with the layout of the vehicle components (Figure 14-11). The figure identifies the location of the following components: Component

Location

Description

1.

12-volt battery

LR of trunk

Typical lead-acid battery used to operate accessories

2.

HV battery pack

Rear seat back support, in trunk

274 NiMH battery pack

3.

HV power cables

Under-carriage and engine compartment

Thick, orange cables carrying HV DC and AC current

4.

Inverter

Engine compartment

Converts DC to AC for the electric motor and AC to DC to recharge the battery pack

5.

Gasoline engine

Engine compartment

Powers vehicle and powers generator to recharge battery

6.

Electric motor

Engine compartment

AC PM motor in transaxle to power vehicle

7.

Electric generator

Engine compartment

AC generator in transaxle used to recharge battery pack

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2

1

5

3 7

6 4

Gas combustion engine HV power pack Traction motor and transaxle

Motor controller and power inverter

12-volt battery

Figure 14-11  Locations of components on the Toyota Prius.

Only a certified technician should disable the high-voltage system by disconnecting the negative terminal of the 12-volt auxiliary battery. This is located in the left rear of the trunk. Disconnecting the auxiliary battery shuts down the high-voltage circuit. For additional protection, wait 5 minutes, and then remove the service plug located through an access port in the trunk (Figure 14-12). Wear certified insulated rubber class “0” 1,000 volt lineman’s gloves when removing the service plug. Always carefully check the gloves for pinholes. Blow slightly into them like a balloon, fold the cuffs and see that they do not

Lineman’s gloves are highly insulated rubber gloves that protect the technician from lethal high voltages.

High voltage and service warning

Service plug

Figure 14-12  The high-voltage service plug is located in the trunk. Use lineman’s gloves to switch power off. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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GRACE READY

km/h MPH

F

P R N D B

CHECK

BRACE

ABS

E

Figure 14-13  Make sure the Ready light is off during service.

leak any air. Even a very small hole could allow a deadly spark to penetrate and reach you. After removing the service plug, wait at least 10 minutes to allow full discharge of the high-voltage condensers inside the inverter. Once the high-voltage system has fully discharged, you may diagnose and repair the Prius gas engine similar to most engines. This is a newly designed engine; be sure to use proper procedures and service specifications. If service or repair includes working around air-conditioning components, make sure to follow proper procedure as some HEV compressors run off of high voltage, use special oil and require a designated Refrigerant Recovery, Recycling, and Recharging Machine for servicing.

Oil and Filter Change Service (Prius) To avoid a reduction in fuel economy, startability, or possible engine damage always use the recommended engine oil. Make sure the “Ready” light is off during service (Figure 14-13)” into the Oil and Filter Change Service.

Hybrid Engine Compression Testing (Prius) Caution It may be necessary to make sure that the ignition is off and the key is the recommended distance from the vehicle to prevent the possibility of engine start-up for HV battery charging during service.

Be sure to look for updated tools and procedures before testing. Adhere to the vehicle manufacturer’s recommended procedures and service specifications for the specific vehicle being tested. Due to the Idle/Stop feature and higher cranking rpm (1,200) on hybrid vehicle engines, special compression test procedures may be required by the manufacturer. 1. Put the engine in Inspection Mode (Maintenance Mode); see Inspection Mode Procedure. 2. Warm the engine up. 3. Shut the engine off and remove the spark plugs. 4. Insert a compression gauge into the first spark plug hole. 5. Connect the factory or enhanced scan tool to the data link connector. 6. Turn the ignition switch on. 7. Using the scan tool make sure the HV battery is fully charged. 8. Enter the following menus: Diagnosis/Enhanced OBD II/ HV Powertrain ECU / Active Test / Compression Request Test (slows cranking speed to the standard 250–300 rpm) / ON. 9. Depress and hold the brake pedal, and turn the ignition switch on (READY). 10. Check the compression for each cylinder to make sure it meets the manufacturer’s specifications and that they are within 15 percent of each other. 11. Reinstall the spark plugs. 12. Clear the diagnostic trouble codes (DTCs).

Inspection Mode Procedure (Prius) Be sure to look for updated tools and procedures before testing. Adhere to the v­ ehicle manufacturer’s recommended procedures and service specifications for the specific ­vehicle being tested. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicle Service

R N D

P

MAINTENANCE MODE 000 00 0 0 10637Ml

Figure 14-14  Follow the manufacturer’s service procedure to enter Maintenance or Inspection Mode.

Activating Maintenance Mode (Without a Scan Tool) 1. Perform the following steps in 60 seconds. a. Turn the ignition switch on (IG). b. With the shift lever in P, fully depress the accelerator pedal twice. c. With the shift lever in N, fully depress the accelerator pedal twice. d. With the shift lever in P, fully depress the accelerator pedal twice. 2. Make sure that “MAINTENANCE MODE” is displayed on the multi-information display (Figure 14-14). 3. While depressing the brake pedal, start the engine by turning the ignition switch on (READY). Note: In maintenance mode and with the shift lever in P, the idle speed is approximately 1,000 rpm. When the accelerator pedal is halfway, the engine speed will increase to 1,500 rpm midway with the shift lever in P. When the accelerator pedal is depressed more than midway or when the accelerator pedal is depressed fully, the engine speed increases to approximately 2,500 rpm.

Follow the manufacturer’s service procedure to enter Maintenance or Inspection Mode.

COOLING SYSTEM SERVICE Draining Procedures 1. Remove the left-side engine cover to gain access to the heated coolant storage pump. 2. Disconnect the heated coolant storage pump connector to prevent the circulation of potentially hot coolant. 3. Locate all three coolant drain plugs located at the bottom of the heated coolant storage tank, lower left side of the radiator, and the rear of the engine block to drain the hoses. Then loosen all three coolant drain plugs. 4. Remove the radiator cap. 5. Drain the coolant into a drain pan. 6. When empty, tighten all three coolant drain plugs. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Cooling System Air Bleed and Refill Procedure 1. Connect a hose from the radiator bleeder plug to the reservoir. Make sure that the other end of the hose is submerged in the new coolant. 2. Loosen radiator air bleeder of the driver’s side of the radiator, remove the radiator cap, and fill the radiator to the top with the coolant. 3. Tighten the radiator bleeder plug and install the radiator cap. 4. Fill the reservoir tank to the full level. 5. Connect the heated coolant storage pump connector. 6. Connect the factory or a capable enhanced scan tool to the DLC. Using the scan tool turn on the water pump by selecting Active Tests; then Run Water Pump. 7. Loosen the radiator bleeder plug, remove the radiator cap, and top up the radiator with the coolant. 8. Tighten the radiator bleeder and install the radiator cap. 9. With the scan tool enter the Inspection Mode. 10. Run the engine until the thermostat opens and the radiator fan cycles on and off. 11. Turn the key off and let it sit until the engine cools down. 12. Remove the radiator cap and top up the radiator and the reservoir tank.

SERVICING THE HONDA CIVIC HYBRID The Civic hybrid runs current at 144 volts through brightly colored orange cables. Its Integrated Motor Assist (IMA) system uses a 1.3-liter gasoline engine and a DC brushless motor (Figure 14-15). You must shut off the high-voltage electrical circuits and isolate the IMA system before servicing its components. Do not touch the high-voltage cables without lineman’s gloves (Figure 14-16). To isolate the high-voltage circuit, turn the high-voltage battery module switch to off. Secure the switch in the off position with the locking cover before servicing the IMA system. Wait at least 5 minutes after turning off the battery module switch, and then disconnect the negative cable from the 12-volt battery. Test the voltage between the high-voltage battery cable terminals with a voltmeter. Do not disconnect them until the voltage is below 30 volts. Again, once you have safely disabled the high-voltage system, you can use your skills and the service information to service the engine and its components. The 1.3-liter in-line High-voltage cables

Figure 14-15  Honda’s IMA system “engine” compartment.

Figure 14-16  The high-voltage cables are routed through the engine compartment, but you cannot miss them with their bright orange color. Disable the high-voltage system before touching them.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicle Service

Figure 14-17  Underneath the HEV covers lies a typical four-cylinder engine that you should feel competent to work on.

Figure 14-18  This vehicle uses 0W-20 motor oil. Follow the manufacturer’s service information carefully to help you provide excellent work on any vehicle.

four-cylinder engine uses a coil-on-plug ignition (Figure 14-17). Note that Honda specifies 0W-20 motor oil in this engine (Figure 14-18). Follow the manufacturer’s service information carefully on these new engines.

HEV WARRANTIES To reassure the public about the new technology and encourage consumer confidence, most HEV manufacturers offer extensive warranties on the battery packs and the hybrid components. You should always consult the manufacturer’s service information before recommending expensive repairs to consumers of these vehicles, even as the vehicles age and you begin to see them in independent repair facilities. A few examples are as follows: Ford Escape

8 years/80,000 miles on battery pack*

Honda HEV

8 years/80,000 miles on battery pack*

Toyota Prius

8 years/100,000 miles on battery pack* and on the hybrid power plant, including the engine

*

Battery packs must be warranted for 10 years/150,000 miles in “green states” (CA, MA, VT, NY, ME)

CASE STUDY A friend who owns a Honda Civic hybrid called the other day concerned because “the light that looks like an engine” was on. Although the vehicle was still under warranty, I took my scan tool and hooked it up to the powertrain control module diagnostic link connector. The diagnostic trouble code indicated a gross evaporative emissions leak. We checked the gas cap and found it loose; tightening it three clicks solved the problem. A simple explanation of the system and reassurance that it would also have happened on a conventional vehicle relieved my friend’s fears that his advanced technology vehicle was going to give him hi-tech trouble.

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ASE-STYLE REVIEW QUESTIONS 1. Technician A says that propane is not flammable unless it is under pressure. Technician B says that the fuel system should be disabled before performing mechanical repairs on the engine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that most LPG engines have higher compression pressures than gas engines. Technician B says that engines run on LPG may last twice as long as their gas counterparts. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. When working on an LPG engine performance concern, Technician A says to check the LPG ­system ­components first. Technician B says that more repairs are required on the base engine than on the LPG system. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B 4. Technician A says that CNG is not explosive, because it is lighter than air. Technician B says that CNG is odorless. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. Technician A says to turn the fuel control valves clockwise to shut fuel off. Technician B says that you should purge the fuel from the lines before disconnecting CNG components. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. Each of the following is a service caution when working on a CNG vehicle except: A. Use ventilation equipment when starting the vehicle in the shop. B. Do not modify CNG fuel system components. C. Run the vehicle with the fuel shut off to purge the fuel from the lines. D. Use only epoxy when repairing a CNG cylinder. 7. Technician A says that a CNG cylinder must be inspected every five years. Technician B says that a CNG cylinder must be removed to be inspected. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 8. A minimum voltage of _______________ can be lethal to humans. C. 42 volts A. 24 volts B. 30 volts D. 120 volts 9. Technician A says that disconnecting the 12-volt auxiliary battery on a Toyota Prius isolates the high-voltage circuit. Technician B says that there is a service plug to isolate the high-voltage system located in the trunk of a Prius. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 10. Technician A says that voltages on an HEV may reach 500 volts. Technician B says that NiMH battery electrolyte can be neutralized with baking soda. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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ASE CHALLENGE QUESTIONS 1. Technician A says that an LPG vehicle runs with fuel pressures over 200 psi. Technician B says that an LPG vehicle does not need spark plugs replaced at regular intervals. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 2. Technician A says that if the fuel pressure ­regulator fails on a CNG vehicle, the engine may not start. Technician B says that compression on a CNG vehicle will be lower than on a gas engine. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 3. Technician A says that gasoline is more explosive in the shop environment than CNG. Technician B says that the manual shut-off valve turns fuel off at the CNG cylinder. Who is correct? C. Both A and B A. A only B. B only D. Neither A nor B

4. Technician A says that if an electric motor will not run, one of the first things to check would be the fuse. Technician B says that you can pull the fuse out and look at it to see if it is blown. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 5. An HEV comes in on a tow truck. The HEV’s owner said it just stopped moving, even though the battery indicator and fuel levels were both above half. Technician A says to check the fuel pressure. Technician B says to check the battery voltage. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Alternative Fuel and Advanced Technology Vehicle Service

Name ______________________________________

Date __________________

673

JOB SHEET

86

SERVICING AN LPG OR CNG VEHICLE Upon completion of this job sheet you should be able to properly disable the fuel system of an alternative fuel vehicle and perform a compression test. Tools and Materials • Technician’s tool set • Safety glasses • Special tools as required • Compression tester Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN _____________________________ Engine type and size ____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Is the vehicle you are working on a dedicated or retrofitted alternative fuel vehicle?

h

2. Locate the service information for disabling the fuel system. Describe the procedure below: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Disable the fuel system according to the manufacturer’s recommended procedure, and have your instructor check your work. 4. Locate the procedure and specifications for performing a compression test on the vehicle you are working on. What is the compression specification?

h

5. Disable the ignition system, block open the throttle, and remove the spark plugs.

h

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Task Completed 6. Perform a compression test as instructed by the service information, and record your results. Cylinder no. 1 ______________________________________________________________ Cylinder no. 2 ______________________________________________________________ Cylinder no. 3 ______________________________________________________________ Cylinder no. 4 ______________________________________________________________ Cylinder no. 5 ______________________________________________________________ Cylinder no. 6 ______________________________________________________________ Cylinder no. 7 ______________________________________________________________ Cylinder no. 8 ______________________________________________________________ 7. Are any of the cylinders below specification?

h Yes h No

If there are cylinders below specification, perform a wet compression test or leakdown test as directed by your teacher. 8. Properly reinstall the spark plugs, close the throttle, and enable the ignition system.

h

9. Locate the instructions in the service information for enabling the fuel system, and describe the procedure. _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 10. Enable the fuel system properly, and have the instructor check your work. Task completed properly?

h

11. Attach exhaust equipment; set the parking brake; start the vehicle, and ensure that it is running properly. Clean up all tools and equipment.

h

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Alternative Fuel and Advanced Technology Vehicle Service

Name ______________________________________

Date __________________

RESEARCHING AN ADVANCED TECHNOLOGY VEHICLE Upon completion of this job sheet, you should be able to research and locate research relevant automotive information and understand the basic operation of an advanced technology vehicle. Tools and Materials • Internet or library access Procedure Choose a production hybrid electric vehicle that is currently being sold in North America for your research. Describe the vehicle being researched: Year _____________________ Make ________________________________________________ Model __________________________________________________________________________ Procedure 1. Provide a basic description of the power plant. __________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What type(s) of power sources are used? ________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. What are the engine classifications? Displacement _______________________________ Cylinders _______________ Configuration _______________ Fuel used ______________ Torque ___________________________ HP ______________________________________ Estimated fuel economy: city _____________________ highway _____________________ Emissions rating ______________________ (ULEV, SULEV, AT-PZEV) 4. What type of electric motor(s) is used? _________________________________________ What is its torque rating? _____________________________________________________ 5. Describe the basic power flow of the electric motor(s) and engine from a stop sign up through acceleration to cruising at highway speeds. _______________________________ _________________________________________________________________________ _________________________________________________________________________

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_________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. What is the base price of this vehicle? _________________________________________ 7. If you were considering buying this vehicle, what advantages and disadvantages would affect your decision? _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Name ______________________________________

Date __________________

677

JOB SHEET

88

DISABLING THE HIGH-VOLTAGE BATTERY PACK ON A HYBRID ELECTRIC VEHICLE Upon completion of this job sheet, you should be able to safely and properly disable the high-voltage battery on a hybrid electric vehicle. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.9.

Identify hybrid vehicle internal combustion engine service precautions.

This job sheet addresses the following MLR task for Engine Repair: A.7.

Identify hybrid vehicle internal combustion engine service precautions.

Tools and Materials • Lineman’s rubber gloves (high-voltage protective gloves) • Hybrid electric vehicle Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Set the parking brake on the vehicle.

h

2. Move the shift lever to park, turn the ignition switch to the Off position, and place the key on a bench outside of the vehicle.

h

3. Disconnect the negative terminal from the 12-volt auxiliary battery.

h

4. On some models, you need to open the trunk and remove some panels to gain access to the disabling switch. Describe where the switch is located on the vehicle you are working on. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. While wearing the special gloves, turn the high-voltage switch to the Off position.

h

6. Using the service manual as a guide, describe how long it takes to depower the highvoltage battery pack so that it is safe. _________________________________________________________________________ _________________________________________________________________________

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Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Name ______________________________________

Date __________________

679

JOB SHEET

89

PERFORMING A COMPRESSION TEST ON A HYBRID ELECTRIC VEHICLE Upon completion of this job sheet, you should be able to properly perform a compression test on a hybrid electric vehicle. NATEF Correlation This job sheet addresses the following AST/MAST task for Engine Repair: A.9.

Identify hybrid vehicle internal combustion engine service precautions.

This job sheet addresses the following MLR task for Engine Repair: A.7.

Identify hybrid vehicle internal combustion engine service precautions.

Tools and Materials • Compression tester • Hybrid electric vehicle • Manufacturer’s scan tool • Oil can • Spark plug socket • Spark tester Describe the vehicle being worked on: Year _____________________ Make _____________________ Model _____________________ VIN ____________________________ Engine type and size _____________________________ Procedure

Task Completed

Your instructor will provide you with a specific vehicle. Write down the information, and then perform the following tasks: 1. Check the oil level and correct as needed.

h

2. Locate the compression specifications for the engine you are working on, and record them. ______________________________________________________________________ _________________________________________________________________________ 3. Start the engine, and allow it to idle until the engine is moderately warm. Allow it to cool slightly before removing the spark plugs. Note: You may have to drive an HEV at highway speed to get the engine to turn on. 4. Remove the spark plugs, and note their condition. Describe your results. _________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. Connect the manufacturer’s scan tool or handheld tester to the vehicle.______________________________________________________________________

h

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6. Install the compression tester adaptor into the number 1 spark plug hole, and crank the engine over five times using the scan tool or handheld tester. Note: Refer to the operator’s manual or the manufacturer’s service manual for specific directions on operation. Record your results. __________________________________________________________ Repeat for each cylinder, and describe your results. Cylinder no. 2 _____________________________________________________________ Cylinder no. 3 _____________________________________________________________ Cylinder no. 4 _____________________________________________________________ Cylinder no. 5 _____________________________________________________________ Cylinder no. 6 _____________________________________________________________ Cylinder no. 7_____________________________________________________________ Cylinder no. 8 _____________________________________________________________ 7. Analyze the results of the compression test, and note any recommended repairs or tests. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 8. Identify the cylinder(s) with the lowest compression. Squirt 2 tablespoons of oil into the weak cylinder, and perform another compression test on that cylinder. Note the new results, and describe what problem this indicates. ____________________________ _________________________________________________________________________ _________________________________________________________________________ 9. Based on your tests and results, what are your recommendations for further testing and repairs? _________________________________________________________________________ _________________________________________________________________________

Instructor’s Response ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

APPENDIX A ASE PRACTICE EXAM

1. Two technicians are discussing the markings on the heads of bolts (cap screws): Technician A says the higher the number of lines, the higher the strength of the bolt. Technician B says the higher the number on the metric bolts, the higher the grade. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

6. A battery is being tested: Technician A says that a capacity (load) test will draw current from the battery. Technician B says that a conductance test will test the battery without drawing current from the battery. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

2. A metric bolt size of M8 means: A. The bolt is 8 mm long. B. The bolt is 8 mm in diameter. C. The pitch (the distance between the crest of the threads) is 8 mm. D. The bolt is 8 cm long.

7. A starter motor cranks the engine too slowly to start: Technician A says that the cause could be a weak or defective battery. Technician B says that the cause could be loose or corroded battery cable connections. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

3. On a metric bolt size M8 × 1.5, the 1.5 means: A. The bolt is 1.5 mm in diameter. B. The bolt is 1.5 cm long. C. The bolt has 1.5 mm between the crest of the threads. D. The bolt has a strength grade of 1.5. 4. The cylinder head bolts have been removed from an engine. The manufacture of an engine requires replacement of these bolts for the installation procedure of the cylinder head. This is because: A. They are torque-to-yield bolts. B. The bolts are likely to be dirty and rusty. C. The bolts have been updated. D. The bolt grade will be reduced after regular service and use. 5. If the bore of an engine is increased without any other changes except for the change to propersize replacement pistons, the displacement will  and the compression . rate will  A. Increase; increase C. Decrease; increase B. Increase; decrease D. Decrease; decrease

8. At the normal service interval for an oil change, the technicians notice that before draining the old oil, the level reads just below the normal level on the dipstick: Technician A says that all engines will consume some amount of oil within the normal service interval. Technician B says that the technician should check TSBs and inform the customer. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 9. An engine uses an excessive amount of oil: Technician A say that clogged oil drain-back holes in the cylinder head could be the cause. Technician B says that worn piston rings could be the cause. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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Appendix A

10. Starter motor current draw during cranking is excessive. Technician A says that a defect in the engine may be the cause. Technician B says that the starter motor may be defective. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 11. Two technicians are discussing torquing cylinder head bolts: Technician A says that many engine manufacturers recommend replacing the head bolts after each use. Technician B says that many manufacturers recommend tightening the head bolts to a specific torque and then turning the bolts an additional number of degrees. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 12. Engine ping (spark knock or detonation) can be . caused by A. Advanced ignition timing B. Retarded ignition timing 13. Two technicians are discussing the diagnosis of a lack-of-power problem: Technician A says that a jumped timing chain could be the cause. Technician B says that retarded ignition timing could be the cause. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 14. An engine equipped with a turbocharger is burning oil (blue exhaust smoke) all the time. Technician A says that a defective wastegate could be the cause. Technician B says that a plugged PCV system could be the cause. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B

15. An engine idles roughly and stalls occasionally: Technician A says that using fuel with too high an RVP level could be the cause. Technician B says that using winter-blend gasoline during warm weather could be the cause. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 16. Technician A says that coolant flows through the engine passages and does not flow through the radiator until the thermostat opens. Technician B says that the temperature rating of the thermostat indicates the temperature of the coolant when the thermostat is opened fully. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 17. Technician A says a higher concentration of water in a vehicle’s coolant will protect it better from rust and corrosion buildup. Technician B says that a 50/50 mix of antifreeze and water is the ratio recommended by most vehicle manufacturers. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 18. Technician A says that the radiator pressure cap is designed to raise the boiling point of the coolant. Technician B says that the radiator pressure cap helps prevent cavitation and therefore improves the efficiency of the water pump. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 19. Technician A says that used antifreeze coolant is often considered to be hazardous waste. Technician B says that metals absorbed by the coolant when it is used in an engine are what make the antifreeze fatally poisonous to animals. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

ASE Practice Exam

20. A water pump has been replaced three times in three months: Technician A says that the drive belt(s) may be installed too tightly. Technician B says that a cooling fan (mounted directly on the water pump) may be bent or out of balance. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 21. The “hot” light on the dash is being discussed by two technicians. Technician A says that the light comes on if the cooling system temperature is too high for safe operation of the engine. Technician B says that the light comes on whenever there is a decrease (drop) in cooling system pressure. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 22. An engine noise is being diagnosed: Technician A says that a double knock is likely to be due to a worn rod bearing. Technician B says that a knock only when the engine is cold is usually due to a worn ­piston pin. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 23. A compression test gave the following results: cylinder number 1 = 155, cylinder number 2 = 140, cylinder number 3 = 110, cylinder number 4 = 105. Technician A says that a defective (burned) valve is the most likely cause. Technician B says that a leaking head gasket could be the cause. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B

683

24. Two technicians are discussing a compression test: Technician A says that the engine should be turned over with the pressure gauge installed for “two puffs.” Technician B says that the maximum difference between the highest-reading cylinder and the lowest-reading cylinder should less than 20 percent. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 25. Technician A says that oil should be squirted into all of the cylinders before taking a compression test. Technician B says that if the compression greatly increases when some oil is squirted into the ­c ylinders, it indicates defective or worn piston rings. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 26. During a cylinder leakage (leak-down) test, air is noticed coming out of the oil fill opening. Technician A says that the oil filter may be clogged. Technician B says that the piston rings may be worn or defective. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 27. A cylinder leakage (leak-down) test indicates 30 percent leakage, and air is heard coming out of the air inlet. Technician A says that this indicates a slightly worn engine. Technician B says that one or more intake valves are defective. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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684

Appendix A

28. Two technicians are discussing a cylinder power balance test: Technician A says the more the engine rpm drops, the weaker the cylinder. Technician B says that all cylinder rpm drops should be within 50 rpm of each other. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

33. Technician A says that pistons should be removed from the crankshaft side of the cylinder when disassembling an engine, to prevent possible piston or cylinder damage. Technician B says that the rod assembly should be marked before disassembly. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

29. Technician A says that a low vacuum reading can be an indication of an intake manifold leak. Technician B says that a sticking valve is indicated by a fluctuating valve gauge needle reading. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

34. Before the valve is removed from the cylinder head: A. The valve spring should be compressed and locks removed. B. The valve tip edges should be filed if the tip is mushroomed. C. The ridge should be removed. D. Both A and B

30. Technician A says that black exhaust smoke is an indication of a too-rich air-fuel mixture. Technician B says that white smoke (steam) is an indication of coolant being burned in the engine. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 31. Excessive exhaust system back pressure has been measured: Technician A says that the catalytic converter may be clogged. Technician B says that the muffler may be clogged. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 32. A head gasket failure is being diagnosed: Technician A says that an exhaust analyzer can be used to check for HC when the tester probe is held above the radiator coolant. Technician B says that a chemical block tester changes color in the presence of combustion gases. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

35. A steel wire brush should be used to clean the gasket surface of an aluminum cylinder head. A. True B. False 36. Technician A says that all valvetrain parts that are to be reused should be kept together. Technician B says that valve springs should be tested. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 37. A cast-iron cylinder head is checked for warpage using a straightedge and a feeler (thickness) gauge. The amount of warpage on a V-8 cylinder head is 0.002 in. (0.05 mm). Technician A says that the cylinder head should be resurfaced. Technician B says that the cylinder head should be replaced. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 38. Technician A says that a dial indicator (gauge) is often used to measure valve guide wear by measuring the amount by which the valve head is able to move with the valve stem in the guide. Technician B says that a ball gauge can be used to measure the valve guide. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

ASE Practice Exam

39. Technician A says that a worn valve guide can be reamed and a valve with an oversize stem can be used. Technician B says that a worn valve guide can be replaced with a bronze insert to restore the cylinder head to useful service. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 40. Technician A says that worn integral guides can be repaired by knurling. Technician B says that worn insert guides can be replaced. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 41. Typical valve-to-valve guide clearance should be  . A. 0.001 to 0.003 in. (0.025 to 0.076 mm) B. 0.010 to 0.030 in. (0.25 to 0.76 mm) C. 0.035 to 0.060 in. (0.89 to 1.52 mm) D. 0.100 to 0.350 in. (2.54 to 8.90 mm) 42. Before a valve spring is reused, it should be checked for . A. Squareness C. Tension B. Free height D. All of the above 43. Many manufacturers recommend that valves be ground with an interference angle. This angle is the difference between the . A. Valve margin and valve face angles B. Valve face and valve seat angles C. Valve guide and valve face angles D. Valve head and margin angles 44. A cylinder is 0.008 in. out of round: Technician A says that the block should be bored and oversize pistons installed. Technician B says that oversize piston rings should be used. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 45. After the engine block has been machined, the block should be cleaned with . A. A stiff brush and soap and water B. A clean rag and engine oil C. WD-40 D. Spray solvent washer

685

46. Two technicians are discussing ring end gap: Technician A says that the ring should be checked in the same cylinder in which it is to be installed. Technician B says that the ends of some piston rings can be filed if the clearance is too small. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 47. Technician A says that connecting rod caps should be marked when the connecting rod is ­disassembled and then replaced in the exact same location and direction on the rod. Technician B says that each piston should be ­fitted to each individual cylinder for best results. Which technician is correct? A. A only C. Both A and B B. B only D. Neither A nor B 48. A bearing shell is being installed in a connecting rod. The end of the bearing is slightly above the parting line. Technician A says that this is normal. Technician B says that the bearing is too big. Which technician is correct? C. Both A and B A. A only B. B only D. Neither A nor B 49. Technician A says that before servicing a CNG system, you should turn the fuel control valve clockwise until it stops. Technician B says you must also turn off the manual shut-off valve. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B 50. Technician A says that hybrid electric ­vehicles operate with voltage levels that can be deadly. Technician B says that highly insulated lineman’s gloves must be worn when disabling the high-voltage system of a Toyota Prius. Who is correct? A. A only C. Both A and B B. B only D. Neither A nor B

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APPENDIX B SPECIAL TOOLS SUPPLIERS

Ajax Lifting Equipment Roseville, MI

Mac Tools Washington Courthouse, OH

Bear Automotive Service Equipment Milwaukee, WI

Magnaflux Corporation Chicago, IL

Blackhawk Automotive Inc. Waukesha, WI

Mitchell International San Diego, CA

Dana Corporation Ann Arbor, MI

OTC Division, SPX Corporation Owatonna, MN

Federal Mogul Corporation St. Louis, MO

Permatex Inc Hartford, CT

Fluke Corporation Everett, WA

Sealed Power Corporation Muskegon, MI

Gates Corporation Denver, CO

Sioux Tools Inc. Sioux City, IA

KD Tools Danaher Tool Group Lancaster, PA

Snap-on Tools Inc. Kenosha, WI

K-Line Industries Inc. Holland, MI

Sunnen Products Company St. Louis, MO

Kwik-Way Manufacturing Company Marion, IA

Winona-Van Norman Machine Company Winona, WI

Lisle Corporation Clarinda, IA

686

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

APPENDIX C MANUFACTURERS’ SERVICE INFORMATION CENTERS Acura See Honda.

Lexus See Toyota.

Audi erwin.audi.de 800-544-8021

Maserati www.maseratiusa.com

Bentley www.bentleytechinfo.com BMW www.bmwtechinfo.com Chrysler/Dodge/Eagle/Jeep/Plymouth www.techauthority.com 800-890-4038 Ferrari www.ferrariusa.com Fiat www.techauthority.com Ford/Lincoln/Mercury www.motorcraft.com General Motors Buick/Cadillac/Chevrolet/Geo/GMC/Hummer/ Oldsmobile/Pontiac/Saturn www.gmtechinfo.com 800-825-5886 800-272-8876 (Saturn) Honda/Acura www.serviceexpress.honda.com Hyundai www.hmaservice.com Infiniti See Nissan. Isuzu www.isuzutechinfo.com Jaguar www.jaguartechinfo.com Kia www.kiatechinfo.com 866-542-8665 Lamborghini 781-788-0600 Land Rover www.landrovertechinfo.com

Mazda www.mazdatechinfo.com 800-824-9655 Mercedes-Benz www.startekinfo.com Mini www.minitechinfo.com Mitsubishi www.mitsubishitechinfo.com Nissan/Infiniti www.nissantechinfo.com www.infinititechinfo.com 440-572-0725 Porsche www.techinfo.porsche.com Saab www.saabtechinfo.com Scion See Toyota. Subaru www.techinfo.subaru.com 866-428-2278 Suzuki www.suzukitechinfo.com Tesla https://service.teslamotors.com Toyota/Scion/Lexus www.techinfo.toyota.com www.techinfo.scion.com www.techinfo.lexus.com 800-622-2033 Volkswagen erwin.volkswagen.de 800-822-8987 Volvo www.volvotechinfo.com 800-258-6586

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687

APPENDIX D METRIC CONVERSION CHARTS

To convert these

to these,

multiply by:

TEMPERATURE Degrees Fahrenheit

Degrees Fahrenheit

Degrees Celsius

1.8 then + 32 0.556 after adding 32

LENGTH Inches Millimeters Feet Meters Miles Kilometers

0.03937 25.4 3.28084 0.3048 0.62137 1.60935

AREA Square Centimeters Square Inches

Square Inches Square Centimeters

0.155 6.45159

VOLUME Cubic Centimeters Cubic Inches Cubic Centimeters Liters Liters Cubic Inches Liters Quarts Liters Pints Liters Ounces Milliliters Ounces

688

to these,

multiply by:

WEIGHT

Degrees Celsius

Millimeters Inches Meters Feet Kilometers Miles

To convert these

Cubic Inches Cubic Centimeters Liters Cubic Centimeters Cubic Inches Liters Quarts Liters Pints Liters Ounces Liters Ounces Milliliters

0.06103 16.38703 0.001 1,000 61.025 0.01639 1.05672 0.94633 2.11344 0.47317 33.81497 0.02957 0.3381497 29.57

Grams Ounces Kilograms Pounds

Ounces Grams Pounds Kilograms

0.03527 28.34953 2.20462 0.45359

WORK Centimeter-kilograms Inch-Pounds Meter Kilograms Foot-Pounds

Inch-Pounds Centimeter-Kilograms Foot-Pounds Newton-Meters

0.8676 1.15262 7.23301 1.3558

Pounds/Square Inch

14.22334

Kilograms/Square ­Centimeter Pounds/Square Inch Bar Kilopascals Pounds/Square Inch

0.07031

PRESSURE Kilograms/Square ­Centimeter Pounds/Square Inch Bar Pounds/Square Inch Pounds/Square Inch Kilopascals

14.504 0.06895 6.895 0.145

OUNCES TO POUNDS 1 oz 2 oz 3 oz 4 oz 5 oz 6 oz 7 oz 8 oz 9 oz 10 oz 11 oz 12 oz 13 oz 14 oz 15 oz 16 oz

0.0625 lb 0.125 lb 0.1875 lb 0.25 lb 0.3125 lb 0.375 lb 0.4375 lb 0.5 lb 0.5625 lb 0.625 lb 0.6875 lb 0.750 lb 0.8125 lb 0.875 lb 0.9375 lb 1 lb

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APPENDIX E ENGINE SPECIFICATIONS CHART

General Engine Specifications ___________________________ Manufacture of Engine Model Year Engine Block Casting Number(s) Cylinder Head Casting Number(s) Cylinder Block Casting Material Cylinder Head Casting Material Combustion Chamber Design # of Cylinders Bore Stroke Rated Horsepower Compression Pressure Compression Ratio Cooling Capacity

Cyl. Arrangement Firing Order Valve Arrangement Rated Torque Oil Capacity Oil Pressure Oil Type

Engine Torque Specifications ___________________________ Crankshaft Main Bearing Bolts Connecting Rod Bolts/Nuts Oil Pump Housing Water Pump Timing Cover Thermostat Housing Spark Plugs Cylinder Head Bolts Intake Manifold Exhaust Manifold

Rocker Arm Shaft/Stud Vibration Damper Flywheel/Flexplate Flywheel Clutch Pressure Plate Camshaft Caps Timing Tensioner Camshaft Sprocket Oil Pan Oil Pump Bolts/Nuts

Engine Dimensions ___________________________ Camshaft Bearing Journal Diameter Base Circle Runout Cam Lobe lift Valve Lift Intake Valve Timing Exhaust Valve Timing Valve Overlap Duration

Opens @ Opens @

Closes @ Closes @

Intake

Exhaust

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689

690

Appendix E

Crankshaft End Play Main Bearing Journal Diameter Main Bearing Journal Width Main Bearing Clearance Connecting Rod Journal Diameter Connecting Rod Journal Width Maximum Out-of-Round (All Journals) Maximum Taper (All Journals) Cylinder Block Deck Height Deck Clearance Cylinder Bore Diameter (Standard) Maximum Taper Maximum Out-of-Round Maximum Cylinder Block Flatness Connecting Rods Total Length (Center-to-Center) Piston Pin Bore Diameter Connecting Rod Bore Bearing Clearance (Standard) Side Clearance Pistons Piston-to-Bore Clearance Piston Ring Gap Clearance Piston Ring Side Clearance Piston Ring Groove Height Piston Ring Groove Diameter Piston Pin Diameter Piston-to-Pin Clearance Cylinder Head Combustion Chamber Volume Valve Arrangement Valve Guide Inside Diameter Valve Stem-to-Guide Clearance Intake Valve Seat Angle Exhaust Valve Seat Angle Intake Valve Seat Width Exhaust Valve Seat Width Valve Seat Runout Cylinder Head Flatness Cylinder Head Thickness Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Engine Specifications Chart

Rocker Arms & Push Rods Rocker Arm Ratio Push Rod Length Push Rod Diameter Lifter/Tappet Diameter Valves Intake Valve Length Exhaust Valve Length Intake Valve Stem Diameter Exhaust Valve Stem Diameter Intake Valve Head Diameter Exhaust Valve Head Diameter Intake Valve Face Diameter Exhaust Valve Face Diameter Intake Valve Face Angle Exhaust Valve Face Angle Valve Interference Angle Valve Margin Valve Lash

Cold

Hot

Valve Springs Intake Valve Spring Free Length Exhaust Valve Spring Free Length Intake Spring Tension (force@length) Exhaust Spring Tension (force@length) Installed Height

Oil Pressure Oil Pump Gear-to-Body Clearance Oil Pump Gear End Clearance

Oil System @ Idle RPM

@ 2,000 RPM

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691

GLOSSARY

Note: Terms are highlighted in bold, followed by Spanish translation in color. 3Cs  Concern, Cause, and Correction related to why the ­customer brought their vehicle into the shop for repair should be noted on the repair order. Las 3 C  Hay que anotar en el pedido de reparación el problema, la causa y la corrección por lo que el cliente llevó su vehículo al taller para reparación. Abrasive cleaning  Abrasive cleaning uses an abrasive product to clean the surface of grease, rust, and dirt. Limpieza abrasiva El método abrasivo de limpieza es el que utiliza un producto abrasivo para eliminar la grasa, el óxido y la suciedad de una superficie. Airflow restriction indicator  The airflow restriction indicator displays the amount of air filter element restriction. Indicador de restriccion del flujo del aire  El indicador derestricción del flujo del aire muestra la cantidad de restricción del elemento del filtro de aire. Align hone  The align hone is able to hone all bearing bores at the same time to realign them. Alineadora  La alineadora es capaz de pulir al mismo tiempo los diámetros de todos los rodamientos para realinearlos. Aligning bars  Tools used to determine the proper alignment of the crankshaft saddle bores. Barras para alinear  Las herramientas que sirven para determinar el alineamiento correcto de los taladros del asiento del cigüeñal. Aluminum hydroxide  Corrosion products that are carried to the radiator and deposited when they cool off. They appear as dark gray when wet and white when dry. Hidróxido de aluminio  Los productos de corrosion que se llevan al radiador y se depositan al enfriarse. Son de color gris obscuro mojados y se blanquean al secarse. Backlash  The clearance between two parts. Culateo/juego  La holgura entre dos partes. Base circle  The base circle is the diameter across the sides of the camshaft lobe with the lobe facing upward. Círculo de la base  El círculo de la base es el diámetro a través de los lados del compartimiento del árbol de levas con el compartimiento que va hacia arriba. Battery terminal test  A test that checks for poor electrical connections between the battery cables and terminals. Use a voltmeter to measure voltage drop across the cables and terminals. Prueba de los terminates de la batería  Una prueba que averigua las conexiones eléctricas malas entre los cables y los terminales de la bateria. Usa un voltimetro para medir la caida del voltaje entre los cables y los terminales. Bearing  Soft metallic shells used to reduce friction created by rotational forces. Cojinete  Una pieza hueca de metal blanda que sirve para reducir la fricción creada por las fuerzas giratorias.

692

Bell housing  The bell housing is the portion of the transmission that bolts to the back of the engine. Caja de la campana  La caja de la campana es la porción de la transmisión que se fija en la parte posterior del motor. Belt surface  Belt surfacers reface the cylinder head surface using a special type of sanding paper. Pulidor de banda Los pulidores de banda rectifican la superficie de la cabeza del cilindro utilizando un tipo especial de papel de lija. Big end  The end of the connecting rod that attaches to the crankshaft. Extremo grande  Refiere a la extremidad de la biela que se conecta al cigüeñal. Blow-by  The unburned fuel and combustion products that leak past the piston rings and enter the crankcase. Soplado  El combustible no consumido y los productos de la combustión que escapen por los anillos de pistón y entran al cárter. Boost pressure  Boost pressure is the amount of pressure supplied by the turbocharger or supercharger to the intake manifold. Presión impulsadora  La presioón impulsadora es la cantidad de presión que provee el turbocargador o el supercargador al colector de entrada. Boring  The process of enlarging a hole. Escariar  El proceso de agrandar un agujero. Bottom-end knock  A loud, deep knocking noise heard from the lower end of the engine. It is usually an indication of ­serious engine problems, such as worn main or rod bearings or crankshaft, or low oil pressure. Golpe de fondo  Un golpe de fondo es un ruido fuerte que se escucha en el fondo del motor. Es usualmente una indicación de problemas serios con el motor, tales como cojinetes principales o de la varilla o del cigüeñal que están gastados, o por baja presión del aceite. Broach  A broach refaces the cylinder head using metal blades. Broca La broca rectifica la cabeza del cilindro utilizando hojas de metal. Caliper  A precision measuring tool that is used to measure the inside, outside, and depth of an object. Calibres El calibre es una herramienta de precisión para medir el interior, el exterior y la profundidad de un objeto. Camshaft  Shaft containing lobes to operate the engine valves. Arbol de levas  Un eje que tiene lóbulos que operan las válvulas del motor. Camshaft end play  The measure of how far the camshaft can move lengthwise in the block. Juego longitudinal del árbol de levas  El juego longitudinal del árbol de levas es la medida de hasta donde se puede mover el árbol de levas longitudinalmente en el bloque.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Glossary Camshaft position actuator  A hydraulically actuated device that changes the camshaft timing in relation to the crankshaft. Biela de accionamiento de la posición del arbol de levas La biela de accionamiento de la posición del árbol de levas es un dispositivo ac-tuado hidráulicamente que cambia la puesta a punto del árbol de levas en relatión con el cigüeñal. Capacity (load) test  A capacity (load) test draws energy from the battery and measures the amount of voltage drop. Prueba de capacidad (de carga) Una prueba de capacidad (de carga) toma energía de la batería y mide el nivel de caída del voltaje. Carbon monoxide  An odorless, colorless, and toxic gas that is produced as a result of incomplete combustion. Monóxido de carbono  Un gas sin olor, sin color y tóxico que se produce como resultado de una combustión incompleta. Catalytic converter  A catalytic converter reduces tailpipe ­emissions of carbon monoxide, unburned hydrocarbons, and oxides of nitrogen. Catalizador  Un catalizador reduce las emisiones del tubo de escape de monóxido de carbono, hidrocarburos no quemados y óxidos de nitrógeno. Chassis ear  A chassis ear machine uses several small microphones that can be placed under the hood and then routed to the passenger compartment where the driver can use a set of headphones. Detector inalámbrico de sonidos para el chasis  Un detector inalámbrico de sonidos para el chasis utiliza varios micrófonos pequeños que se pueden colocar bajo el capó y luego ser direccionados hacia la cabina donde el conductor puede utilizar un par de auriculares. Chemical cleaning  Chemical cleaning uses chemicals to remove grease, scale, rust, paint, or anything else that is causing an issue because of its presence. Limpieza química Los métodos químicos de limpieza ­utilizan productos químicos para eliminar grasa, sarro, óxido, pintura o cualquier otra sustancia cuya presencia cause un problema. Chemical combustion tester  A chemical combustion tester uses a chemical that reacts to combustion gases. The tester draws fumes off the top of the radiator and changes color in the presence of combustion gases. Probador de bloque químico  Un probador químico en tubo usa un químico que reacciona ante los gases de combustíon. Cuando se pasa aire a través de la solutión por encima del radiador, no debe estar presente ningun gas de combustión. Si hay, se está indicando que existe un problema con la cabeza o con la cabeza de la junta. Compression  The reduction in volume of a gas. Compresión  La reducción del volumen de un gas. Compression gauge  A compression gauge is used to check the compression pressure of an engine cylinder. Calibre de compresión Un manómetro es un dispositivo que se utiliza para verificar la compresión de los cilindros de un motor. Compression testing  A diagnostic test to determine the engine cylinder’s ability to seal and to maintain pressure. Prueba de compresión  Una prueba diagnóstica que determina la habilidad del cilindro del motor de sellar y mantener la presión.

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Conductance test  A battery can be tested in many ways. A ­conductance test sends a low current AC signal into the ­battery and the return signal is analyzed. Prueba de conductancia  Una batería se puede probar de muchas maneras. La prueba de conductancia envía una señal baja de corriente CA a la batería y analiza la señal de retorno. Core plugs  Metal plugs screwed or pressed into the block or cylinder head at locations where drilling was required or sand cores were removed during casting. Tapones del núcleo  Los tapones metálicos fileteados o prensados en el monoblock o en la cabeza de los cilindros ubicados en donde se había requerido taladrar o quitar los machos de arena durante la fundición. Crankshaft end play  The measure of how far the crankshaft can move lengthwise in the block. Juego en el extremo del cigüeñal  La medida de cuánto puede moverse el cigüeñal a lo largo del monoblock. Current draw test  A test that measures the amount of current that the starter draws when actuated. It determines the electrical and mechanical condition of the starting system. Prueba de carga al corriente  Una prueba para medir la cantidad del corriente que consuma el motor de arranque al ser puesto en acción. Determina la condición eléctrica y mecánica del sistema de arranque. Cylinder bore dial gauge  A cylinder bore dial gauge is a special made type of dial gauge that fits in a common engine cylinder. The dial reads similar to other dial gauges. Micrómetro con cuadrante para cilindros El micrómetro con cuadrante para cilindros es un tipo especial de micrómetro con cuadrante que se ensambla en el cilindro de un motor común. El cuadrante se lee de manera similar a otros medidores de cuadrante. Cylinder boring  Cylinder boring makes it possible to bore ­cylinders to accept oversize pistons. Perforatión del cilindro  La perforatión del cilindro hace posible perforar los cilindros para que acepten pistones de gran tamaño. Cylinder leakage test  A cylinder leakage test is performed to measure the cylinder’s capability to seal (or percentage of leak). Prueba de fugas en el cilindro La prueba de fugas del ­cilindro se realiza para medir la estanqueidad del cilindro (o porcentaje de fugas). Deck  The top of the engine block where the cylinder head is attached. Cubierta  La parte superior del monoblock en donde se conecta la cabeza del cilindro. Detonation  A defect that occurs if the air/fuel mixture in the cylinder is burned too fast. Detonatión  Un defecto que ocurre si la mezcla aire/combustible en el cilindro se quema demasiado rápido. Diagnostic link connector (DLC)  A connector, usually located under the dash, that provides access to diagnostic information. Conectador de bieleta de diagnóstico  El conectador de bieleta de diagnóstico es un conectador que generalmente se localiza debajo del tablero de instrumentos, que proporciona acceso a la informatión de diagnóstico.

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694

Glossary

Diagnostic trouble code (DTC)  A coded output from the PCM to identify system faults. Código de diagnóstico de problemas  Un código de diagnóstico de problemas es una salida en código desde el MCM para identificar las fallas del sistema. Dial calipers  Vernier style calipers with a dial gauge installed to make reading of the vernier scale easier and faster. Calibres de carátula  Los calibres tipo vernier equipados con una carátula para facilitar y acelerar la lectura de un escala vernier. Dial indicator  A measuring instrument consisting of a dial face with a needle. The dial is usually calibrated in 0.001-inch ­increments. A spring loaded plunger or toggle lever transfers movement to the dial needle. Indicador de carátula  Un instrumento de medida que consiste de una carátula con una aguja. La carátula suele ser calibrada en incrementos de 0.001 de una pulgada. Un piston tubular cargado de resorte o por una palanca acodada transfere el ­movimiento a la aguja de la carátula. Die  A tool used to repair or cut new external threads. Matriz  Una herramienta para reparar o cortar las roscas exteriores. Diesel exhaust fluid (DEF)  A fluid that is added to some diesel ­vehicles to assist in lowering tailpipe emissions. It is injected into the exhaust. Líquido de escape diesel El líquido de escape diesel (DEF)  Es un fluido que se le agrega a algunos vehículos diesel. Este líquido se pulveriza dentro del tubo de escape en determinadas condiciones de funcionamiento. Diesel particulate filter  Diesel particulate filters trap soot (also known as particulate matter) and are located in the exhaust system. Filtro de partículas para motores diesel Los filtros de partículas para motores diesel capturan el hollín (también denominado partículas) que se encuentra en el sistema de escape. Digital pyrometer  An electronic device that measures heat. Pirómetro digital  Un pirómetro digital es un dispositivo ­electrónico que mide el calor. Dry sleeves  A dry sleeve can be installed into a cylinder block by pressing it in. In this design there is no air gap and no coolant passage between the sleeve and the block. Camisas secas Una camisa seca se puede instalar en un bloque de cilindros presionándola hacia adentro. En este diseño no hay espacio de aire ni paso de refrigerante entre la camisa y el bloque. Dry starts  Increasing the engine speed right after engine ­starting, before oil has filled the system. Arranque en seco  Los arranques en seco se refieren a aumentar la velocidad del motor justo después de encenderlo, antes de que el aceite haya llenado el sistema. Duration  The length of time, expressed in degrees of crankshaft rotation, the valve is open. Duración  La cantidad del tiempo, representado por los grados de rotación del cigüeñal, que esta abierta la válvula. Electrolysis  The chemical and electrical process of decomposition that occurs when two dissimilar metals are joined in the presence of moisture. Electrólisis  Es el proceso electroquímico de descomposición que tiene lugar cuando se unen dos metales diferentes en ­presencia de humedad.

Engine dynamometer  A machine bolted to the engine and used to measure the torque of the engine when it is running. Dinamómetro para motores El dinamómetro para motores es una máquina acoplada al motor que se utiliza para medir el par de torsión del motor cuando está en funcionamiento. Engine hoist  A crane style pump jack that is specially designed to lift an engine out of a vehicle. Motor elevador El motor elevador es un gato mecánico tipo grúa especialmente diseñado para levantar el motor de un vehículo. Engine stand  A special holding fixture that attaches to the back of the engine, supporting it at a comfortable working height. In addition, most stands allow the engine to be rotated for easier disassembly and assembly. Bancada para motor  Un accesorio de apoyo especial que se conecta a la parte trasera del motor. Permite que se soporta el motor en una altura ideal para trabajar. Además, la mayoría de las bancadas permiten la rotación del motor para facilitar el desmontaje y montaje. Environmental Protection Agency (EPA)  A department of the federal government dedicated to reducing pollution and improving environmental quality. Secretaría de Protección del Ambiente  La Agencia de Protección del Ambiente es una agencia del gobierno federal que se dedica a reducir la contaminatión y a mejorar la calidad del ambiente. Exhaust gas analyzer  A diagnostic tool that measures the amount and type of gas in the exhaust stream. Analizadores de gases de escape El analizador de gases de escape es una herramienta de diagnóstico que mide la cantidad y el tipo de gas en la corriente del tubo de escape. Exhaust gas recirculation (EGR) valve  An emission control device that cools the combustion chamber to reduce emissions of oxides of nitrogen. Válvula de recirculatión del gas de emisión  La válvula de recirculatión del gas de emisión es un dispositivo de control de emisiones que enfría la cámara de combustión para reducir las emisiones de los óxidos de nitrógeno. Exhaust valve  An engine part that controls the expulsion of spent gases and emissions out of the cylinder. Válvula de escape  Una parte del motor que controla la expulsión de los gases consumidos y los emisiones del cilindro. Extractor  A special tool that is used to remove a broken bolt from a bolthole. Extractor  Un extractor es una herramienta especial que se usa para quitar un tornillo de un hoyo de tornillo. False guides  Devices that are similar to inserts. Guías falsas  Los dispositivos muy parecidos a las piezas insertas. Feeler gauge  A measuring tool consisting of a series of metal strips cut to precise thicknesses. Galga calibrada  Una serie de hojas metálicas cortadas a los espesores precisos. Flat rate pay  Flat rate pay means that you are paid for each hour of billable work as determined by the manufacturer, an aftermarket labor-estimating guide, or your shop. Tarifa bloque  La tarifa bloque significa que se pagará por cada hora de trabajo realizado como lo determina el fabricante, una guía de estimatión de trabajo por horas extras, o por el taller. Flex fans  Fans designed to widen their pitch at slow engine speeds when more air flow is required through the radiator fins. At higher engine speeds, the pitch is decreased to reduce the horsepower required to turn the fan.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Glossary Ventiladores ajustables  Un diseño de los ventiladores que amplían su paso en las velocidades más bajas que requieren más flujo del aire por los devanados del radiador. En las velocidades más altas el paso se disminuye reduciendo los requerimientos del par de dar las vueltas al ventilador. Floor jack  A portable hydraulic lifting device that is used to lift part of a vehicle off the ground. Gato Un gato de piso es un dispositivo portátil hidráulico de elevación que se utiliza para levantar parte de un vehículo del suelo. Front pipe  The front pipe connects the exhaust manifolds to the catalytic converter or muffler. Tubo frontal  El tubo frontal conecta los colectores de emisión con el catalizador o mofle. Fuel control valve  The fuel control valve on a CNG vehicle is a manually operated valve designed to stop fuel flow from the cylinder. Válvula de control del combustible  La válvula de control del combustible en un vehículo GNC es una válvula que se maneja manualmente diseñada para parar el flujo del combustible que está en el cilindro. Fuel-pressure gauge  A device used to measure the pressure of the fuel system. Manómetro de presión del combustible El manómetro de presión del combustible se utiliza para medir la presión del sistema de combustible. Fuel-pressure regulator  A fuel-pressure regulator is typically a mechanical device that maintains the correct fuel pressure in the fuel rail the injectors sit in. Regulador de la presión del combustible  Un regulador de la presión del combustible es típicamente un dispositivo mecánico que mantiene la presión correcta del combustible en el riel de combustible en donde se asientan los inyectores. Gallery plugs  Metal plugs used to cap the drilled oil passages in the cylinder head or engine block. They can be threaded or pressed into the hole. Tapones de la canalización de aceite  Los tapones metálicos que sirven para estancar los pasajes taladrados del aceite en la cabeza del cilindro o en el monoblock. Pueden ser fileteados o prensados en el agujero. Harmonic balancer (vibration dampener)  A component attached to the front of the crankshaft used to reduce the ­torsional or twisting vibration that occurs along the length of the crankshaft. Equilibrador armónico (amortiguador de vibraciones) Un componente conectado a la parte delantera de un cigüeñal que sirve para reducir las vibraciones torsionales que ocurren por la longitud del cigüeñal. Head  The head of the piston is the top piston surface. Cabeza  La cabeza de un pistón es la superficie superior del pistón. Heel  The camshaft heel is roughly 180° from the lobe high point. This is where the valve will be closed. Talón  El talón del árbol de levas está a aproximadamente 180 grados del punto más alto del compartimiento. Allí es donde se cerrará la válvula. Hydraulic press  A tool used to remove and install components with a tight press fit. Prensa hidráulica  La prensa hidráulica es una herramienta que se usa para quitar e instalar componentes con un cierre apretado.

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Hydrostatic lock  The result of attempting to compress a liquid in the cylinder. Since liquid is not compressible, the piston is not able to travel in the cylinder. Bloqueo hidrostático  El resultado de un intento de comprimir un líquido en el cilindro. Como no se puede comprimir un líquido, el pistón no puede moverse en el cilindro. Impact screwdriver  An impact screwdriver twists the screw as you hit the end of the driver with a hammer. It works very well to remove tightly fastened, rusty, or recessed screws. Destornillador de golpe  Un destornillador de impacto le da vuelta al tornillo mientras se golpea la orilla del destornillador con un martillo. Trabaja muy bien para quitar tornillos muy apretados, oxidados o en retranqueo. Intake manifold  Component that delivers the air or air/fuel mixture to each engine cylinder. Múltiple de admisión  Un componente que entrega el aire o la mezcla del aire/combustible a cada cilindro del motor. Interference angle  Valve design in which the seat angle is 1° greater than the valve face angle to provide a more positive seal. Angulo de interferencia  Un diseño de la válvula en el cual el ángulo del asiento de la válvula es un grado además del ángulo de la cara de la válvula para proveer un sello más positivo. Interference fit  Interference fit components are slightly smaller than the shaft they fit onto or the bore they fit into. This makes a puller or a press necessary for disassembly and reassembly. Ajuste duro  Los componentes de ajuste duro son un poco más pequeños que el eje en el que caben o el orificio en el que están. Esto hace necesario el uso de un arrancador o de una prensa para desensamblarlo y reensamblarlo. Jack stands  (safety stands) Support devices used to hold the vehicle off the floor after it has been raised by the floor jack. Torres (soportes de seguridad)  Los dispositivos de soporte que se emplean para mantener el vehículo levantado del piso despues de que haya sido levantado del piso por un gato hidráulico. Jet valves  Valves used by some manufacturers to direct a stream of oil to the underside of the piston head. Jet valves are ­common on turbocharged engines to keep the piston cool to prevent detonation and piston damage. Válvulas de chorro  Las válvulas empleados por algunos fabricantes para dirigir un chorro de aceite a la parte inferior de la cabeza del pistón. Las válvulas de chorro suelen usarse en los motores turbo-cargados para mantener frío al pistón y para prevenir la deton-ación y los daños al pistón. Knock sensor  A knock sensor is bolted into the engine and senses engine vibrations that resemble knock. It relays this information to the PCM so it can adjust ignition timing to try to reduce knocking. Sensor de golpe  Un sensor de golpe está atornillado al motor y percibe las vibraciones del motor que parezcan golpes. Le envía esta informatión al MCM para que ajuste el encendido de arranque y trate de reducir el golpeteo. Knurl  A special bit that rolls a thread into the guide and causes the metal to rise. Moleta  Una broca especial que enreda un hilo en la guía y causa que se levanta el metal. Knurling  Knurling a valve guide cuts and deforms the metal to straighten it out. Moleteado El moleteado de la guía de una válvula corta y deforma el metal para enderezarlo.

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696

Glossary

kPa  The common unit of pressure measurement using the ­metric system is ­kilopascals. kPa  es una unidad de medida del sistema métrico que significa kilopascales (kPa). Land  A piston land is the area between the ring grooves. Apoyo, contacto  El apoyo o contacto del pistón es el área entre las rodadas de los anillos. Leakdown  The relative movement of the lifter’s plunger in respect to the lifter body. Tiempo de fuga  El movimiento relativo del émbolo de levantaválvulas con relatión al cuerpo del levantaválvulas. Lifters  Mechanical (solid) or hydraulic connections between the camshaft and the valves. Lifters follow the contour of the ­camshaft lobes to lift the valve off its seat. Levantaválvulas  Las conexiones mecanicas (sólidas) o hidráulicas entre el árbol de levas y las válvulas. Los levantaválvulas siguen el contorno de los lóbulos del árbol de levas para levantar la válvula de su asiento. Line boring  A machining process of the main-bearing journals that restores the original bore size by cutting metal using ­cutting bits. Taladrar en serie  Un proceso de rectificatión a máquina de los munoñes del cigüeñal que restaura el tamaño original del ­taladro cortando el metal con brocas para cortar. Lineman’s gloves  Highly insulated rubber gloves that protect the technician from lethal high voltages. Guantes de operador de línea  Los guantes de operador de línea son guantes de hule altamente aislantes que protegen al técnico de un alto voltaje letal. Liners  Thin tubes placed between two parts. Manguitos  Los tubos delgados puestos entre dos partes. Lobe lift  The distance that a cam lobe moves the contacting ­valvetrain component as the cam lobe rotates. Realce del lóbulo  El realce del lóbulo es la distancia que un lóbulo del eje mueve el componente del tren de la válvula de contacto mientras gira el lóbulo del eje. Lockout Tag  should be used to prevent use anytime a piece of machinery or equipment capable of movement is cleaned, ­serviced, adjusted, or being set up. Etiqueta de bloqueo  Debe usarse para evitar el uso cada vez que se vaya a limpiar, dar servicio, ajustar o configurar una pieza de maquinaria o equipo con partes móviles. Lugging  Lugging of the engine results from too high a gear selection for the load. Arrastre  El arrastre de un motor resulta de la selección de una velocidad muy alta para la carga. Machinist’s rule  A multiple scale ruler used to measure distances or components that do not require precise measurement. Regla de acero  Una regla con graduaciones múltiples para medir las distancias o los componentes que no requieren una medida precisa. Magnafluxing  A crack detection method that can be used on any ferrous metal component. Magnets are placed at either end of the component and liquid with metal filings is poured over the component. If there is a crack, the filings line up across the crack and are highlighted under a black light.

Aplicación de la magna flujo  La aplicación de la magna flujo es un método para detectar grietas que puede usarse en cualquier componente metálico ferroso. Los imanes se colocan en cualquier terminal del componente y un líquido con partículas metálicas se vacía sobre el componente. Si hay una grieta, las partículas se forman a lo largo de la grieta y se realzan bajo una luz negra. Malfunction indicator light (MIL)  An amber light on the dash used to alert the driver about an emissions-related powertrain problem. It is on all 1996 and newer passenger cars and lightduty trucks sold in the United States and Canada. Luz indicadora de falla  La luz indicadora de falla es una luz color ámbar en el tablero de instrumentos y se usa para alertar al conductor sobre problemas con una emisión relacionada con el motor. Está presente en los automóviles de pasajeros y en las camionetas de carga li-gera desde los modelos de 1996 en ­adelante que se venden en EU y Canadá. Manual shut-off valve  The manual shut-off valve stops fuel flow from the CNG cylinder(s) to the engine. Válvula de apagado manual  La válvula de apagado manual para el flujo de combustible de los cilindros GNC al motor. Meter  One meter is a little more than three inches longer than a yard. Metro  Un metro es un poco más de 3 pulgadas más largo que una yarda. Microinch  One millionth of an inch. The microinch is the ­standard measurement for surface finish in the American ­customary system. Micropulgada  La millonésima parte de una pulgada. Una microp-ulgada es una unidad común para el acabado de la superficie en el sistema de medida americana. Micrometer  One millionth of a meter. The micrometer is the standard measurement for surface finish in the metric system. Micrómetro  Una millonésima parte de un metro. La medida común para el acabado de la superficie en el sistema métrica. Micrometer  Precision measuring instrument designed to ­measure outside, inside, or depth measurements. Micrómetro  Un instrumento de medidas precisas diseñada para tomar medidas exteriores, interiores o de profundidad. Minor thrust side  The side opposite the side of the rod that is stressed during the power stroke. Lado de empuje menor  El lado opuesto del lado cuyo biela recibe el esfuerzo durante la carrera de potencia. Misfire  A misfire is when a combustion event is incomplete or does not occur at all. Fallo de encendido  El fallo de encendido es cuando un evento de combustion esta incompleto o no sucede del todo. Muffler  A device, mounted to the exhaust system behind the catalytic converter, that reduces engine noise. Mofle  El mofle es un dispositivo montado en el sistema de ­emisiones detrás del catalizador, que reduce el ruido del motor. National Institute of Automotive Service Excellence (ASE)  The National Institute of Automotive Service Excellence (ASE) offers nationally recognized certifications to automobile and heavy-duty truck technicians through a combination of biannual testing and proof of professional experience.

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Glossary Instituto Nacional para la Excelencia del Servicio Automovilístico  El Instituto Nacional para la Excelencia del Servicio Automovilístico ofrece certificaciones reconocidas a nivel nacional a los técnicos de automóviles y camionetas de carga pesada mediante una combinatión de exámenes bianuales y prueba de experiencia profesional. Noid light  Noid lights are used to check the electrical signal sent by the computer to the fuel injectors. Lámpara noid las lámparas noid se utilizan para comprobar la señal eléctrica enviada por la computadora a los inyectores de combustible. Nose  The area just before and just after the peak of the camshaft lobe. Boca  La boca es el área justo antes y después del tope del lóbulo del árbol de levas. OBD II  An OBD II (On Board Diagnostics) vehicle meets an EPA requirement for emissions and also has a standardized computer system and DLC location. OBD II  Un vehículo OBD II (con diagnóstico a bordo) cumple con los requisitos de la EPA respecto de las emisiones y también cuenta con un sistema informático y de localización del conector de diagnóstico (DLC) estandarizado. Occupational Safety and Health Administration (OSHA)  The Occupational Safety and Health Administration is a part of the U.S. government tasked with protecting the health and safety of workers. Administratión de la Salud y Seguridad Ocupacional La Administración de la Salud y Seguridad Ocupacional es una agencia del go-bierno de EU. que se encarga de proteger la salud y la seguridad de los trabajadores. Oil pressure test  Test to determine the condition of the bearings and other internal engine components. Prueba de presión de aceite  Una prueba que se efectua para determinar la condición de los cojinetes u otros componentes interiores del motor. Oil pump  A rotor or gear type positive displacement pump used to take oil from the sump and deliver it to the oil galleries. The oil galleries direct the oil to the high-wear areas of the engine. Bomba de aceite  Un rotor o una bomba de tipo deplazamiento positivo de engrenajes que sirve para tomar el aceite de un suministro y entregarlo a las canalizaciones de aceite. Las canalizaciones de aceite dirigen el aceite a las areas del motor que imponen gastos severos. Open circuit voltage test  Test to determine the battery’s state of charge. It is used when a hydrometer is not available or ­cannot be used. Prueba de voltaje de circuito abierto  Una prueba para ­determinar el estado de carga de la bateria. Se usa cuando no es disponible o no se puede usar un hidrometro. Open pressure  Spring tension when the valve spring is compressed and the valve is fully open. Presión abierta  La tensión de un resorte de la válvula al estar comprimido con la válvula completamente abierta. Out-of-round gauges  Instruments used to measure the ­concentricity of connecting rod bores. Calibradores de ovulado  Los instrumentos para medir la ­concentricidad de los taladros de las bielas.

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Out-of-roundness  A cylinder’s out-of-roundness refers to the difference in diameter measured across the cylinder. In other words, how far from being a perfect circle, and closer to ­resembling an oval is it. Ovalización La ovalización de un cilindro se refiere a la ­diferencia en el diámetro medida transversalmente al eje del cilindro. En otras palabras, qué tan lejos está de ser un círculo perfecto y cuánto más cerca está de parecerse a un óvalo. Overlap  The number of degrees, as measured in degrees of crankshaft rotation, when both the intake and exhaust valves are open near TDC on the exhaust stroke. Solapado  El solapado es el número de grados, como se mide en grados de la rotacion del cigüeñal, cuando ambas válvulas de entrada y de sa-lida están abiertas cerca del PMS en el golpe de salida. Oversize bearings  Bearings that are thicker than standard to increase the outside diameter of the bearing to fit an oversize bearing bore. The inside diameter is the same as standard bearings. Cojinete de medidas superiores  Los cojinetes que son de un espesor más grueso de lo normal para aumentar el diámetro exterior del cojinete para quedarse en un taladro que rebasa la medida. El diámetro interior es lo mismo del cojinete normal. Oxygen sensor  An oxygen sensor sits in the exhaust stream and measures the amount of oxygen present in the exhaust. One use of this sensor is to help the computer to determine whether the engine is running rich or lean and adjust accordingly. Sensor de oxigeno  El sensor de oxígeno se asienta en la corriente de salida y mide la cantidad de oxígeno presente en la salida. Un uso de este sensor es el ayudar a la computadora a determinar si el motor está trabajando en alta o en baja combustibilidad y a hacer los ajustes correctos. Particulates  Small carbon particles present in diesel exhaust that are considered to be pollutants. Microparticulas  Las micropartículas son pequeñas partículas de carbono presentes en las emisiones diesel y se les considera contaminantes. Peening  The process of removing stress in a metal by striking it. Martillar  El proceso de quitar la fatiga de un metal golpeandolo. Pickup tube  A tube used by the oil pump to deliver oil from the bottom of the oil pan. The bottom of the tube has a screen to filter larger contaminants. Tubo de captación  Un tubo empleado por la bomba de aceite para entregar el aceite del fondo del colector de aceite. La parte inferior del tubo tiene una rejilla para filtrar los contaminantes más grandes. Pilot bushings  The pilot bushings or pilot bearings are pressed into the centerline of the crankshaft at the back, or the flywheel. They are used to support the front of the transmission’s input shaft. Casquillos piloto  Los casquillos piloto o cojinetes piloto están apretados hacia adentro de la línea central del cigüeñal al fondo, o del volante. Se usan para apoyar el frente del eje de entrada de la transmisión. Pin boss  A bore machined into the piston that accepts the piston pin to attach the piston to the connecting rod. Mamelón  Un taladro tallado a máquina en el pistón que ­acomoda la espiga del pistón para conectarlo a la biela.

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698

Glossary

Piston slap  A sound that results from the piston hitting the side of the cylinder wall. Golpeteo del pistón  Un ruido resultando del pistón golpeando contra el muro del cilindro. Plastigage  A string-like plastic that is available in different diameters used to measure the clearance between two components. The diameter of the plastigage is exact, thus any crush of the gage material will provide an accurate measurement of oil clearance. Plastigage  Un plástico en forma de hilo disponible en diámetros distinctos que se emplea en medir la holgura entre dos componentes. El diámetro del calibre plástico es preciso, asi cualquier aplastamiento del material del calibre provee una medida ­precisa de la hogura del aceite. Pneumatic tools  Power tools that use compressed air to increase the power and capacity of the tool. Herramientas neumáticas  Las herramientas neumáticas son aquellas que utilizan aire comprimido para aumentar la potencia y la capacidad de la herramienta. Polishing  The process of removing light roughness from the journals by using a fine emery cloth. Polishing can be used to remove minor scoring of journals that do not require grinding. Bruñido  El proceso de quitar la aspereza ligera de los muñones usando una tela abrasiva muy fina. El bruñido puede emplearse en quitar las rayas superficiales de los muñones que no requieren rectificación. Positive crankcase ventilation (PCV) system  An emission control system that routes blow-by gases and unburned oil/fuel vapors to the intake manifold to be added to the combustion process. Sistema (PCV) de ventilación positiva de la caja del ­cigüeñal  Unsistema de emisión que lleva los gases soplados y los vapores del aceite/combustible no quemados al múltiple de entrada para que se pueden añadir al proceso de combustión. Pounds per square inch (psi)  A common measurement of ­pressure using the imperial standard system. Libra por pulgada cuadrada (psi)  es una unidad de medida de presión del sistema anglosajón de medidas. Power balance testing  Test used to determine if all cylinders are producing the same amount of power output. In an ideal situation, all cylinders would produce the exact same amount of power. Prueba del equilibrio de fuerza  Una prueba para determinar si todos los cilindros producen la misma cantidad de potencia de salida. En una situatión ideal, todos los cilindros producirían exactamente la misma cantidad de poder. Power tools  Tools that are operated by an outside power source. This may include batteries, electrical outlets, compressed air, or hydraulic fluid. Herramientas de motor Las herramientas mecánicas son aquellas que utilizan una fuente de energía externa. Estas fuentes pueden incluir baterías, tomacorrientes, aire comprimido o fluido hidráulico. Powertrain control module (PCM)  The vehicle’s computer that controls engine performance and related functions such as fuel and spark control. Módulo de control del motor (MCM)  El modulo de control del motor (MCM) es la computadora del vehículo que controla el funcionamiento del motor y las funciones relacionadas tales como el control del combustible y de la chispa. Preignition  Defect that is the result of spark occurring too soon. Autoencendido  Un defecto que resulta de una chispa que ocurre demasiado temprano.

Prelubrication  Prelubrication entails lubricating the engine or turbocharger bearings or other components before starting the engine. Pre-lubricación  La pre-lubricación implica la lubricatión del motor o de los cojinetes del turbosobrealimentador u otros componentes antes de encender el motor. Pressure plate  The pressure plate couples and uncouples the clutch disc from the flywheel on a manual transmission to transmit engine torque to the transmission. Placa de presión  La placa de presión acopla y desacopla los ­discos del embrague del volante en una transmisión manual para transmitir par motor a la transmisión. Profilometer  A tool capable of electrically sensing the distances between peaks to determine the finish of a cut. Perfilómetro  Una herramiento capaz de detectar electrónicamente las distancias entre dos puntos altos para determinar cuando terminar un corte. Prussian blue  Thick ink used to show the area of seat contact on the valve face. Azul de Prusia  El azul de Prusia es una tinta fuerte que se usa para mostrar el contacto de asiento en la cara de una válvula. Purge solenoid  Part of the evaporative emissions control system and is used to purge fuel vapors from the fuel tank into the intake manifold to be burned. Solenoide de purga  El solenoide de purga es parte del sistema de control de emisiones evaporativas y se usa para purgar los vapores del combustible desde el tanque de la gasolina hacia el colector de admisión para quemarse. Pushrod  A connecting link between the lifter and the rocker arm. Engines designed with the camshaft located in the block use pushrods to transfer motion from the lifters to the rocker arms. Varilla de presión  Una conexión entre la levantaválvulas y el balancín empuja válvulas. Los motores diseñados con el árbol de levas en el bloque usan las varillas de presión para transferir el movimiento de la levantaválvulas a los balancines. Quick disconnect fittings  Fuel line fittings that are removable with a special tool rather than threaded fittings. Montaje de desconectado rápido  Los montajes de desconectado rápido son montajes de la línea del combustible que se pueden quitar con una herramienta especial en vez de montajes enroscados. Radiator  A component consisting of a series of tubes and fins that transfer the heat from the coolant to the air. Radiador  Un componente que consiste de una serie de tubos y aletas que transferen el calor del fluido refrigerante al aire. Registering  Registering the main bearing caps is done by tightening the cap bolts using hand pressure only while rotating the crankshaft. This squares the cap to the block before the bolts are torqued. Ajuste  El ajuste de las tapas de los cojinetes principales se hace al apretar las tapas de los tornillos usando sólo la presión de la mano mientras gira el cigüeñal. Esto escuadra la tapa al bloque antes de que se tuerzan los tornillos. Relief valve  Valve used to prevent excessive oil pressure. Since the oil pump is positive displacement, pressures could increase to a hazardous level at higher engine speeds. The relief valve opens to return oil to the sump and drop pressure in the system. Válvula de rebose  Una válvula que previene una presión excesiva de aceite. Como la bomba de aceite es de desplazamiento positivo, las presiones podrían aumentar a un nivel peligroso en las velocidades más altas. La válvula abre para regresar el aceite al resumidero y bajar la presión del sistema.

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Glossary Repair order  A written legal document that describes the concern (customer complaint), the cause (what needs repair or what is wrong), and the correction that has been made. Orden de reparación  Es un documento legal escrito que describe el problema (el reclamo del cliente), la causa (qué se debe reparar o no funciona) y la corrección realizada. Restricted exhaust  An exhaust system that offers more-thannormal restriction to the exhaust flow. Escape restringido  Es un sistema de escape que ofrece una restricción, mayor a la normal, al flujo de escape. Ridge reamer  A cutting tool used to remove the ridge at the top of the cylinder. Escariador de reborde  Una herramienta de cortar que sirve para quitar el reborde en la parte superior del cilindro. Right-to-Know Laws  Right-to-Know Laws inform workers regarding exposure to hazardous materials. Leyes de derecho de información  Las leyes de derecho de informatión informan a los trabajadores sobre el riesgo de exponerse a los materiales peligrosos. Ring ridge  A ring ridge develops at the top of the cylinder above where the rings scrape and wear down. Carbon also builds up in this area to create a smaller diameter region of the cylinder bore. Canal del anillo  El canal del anillo se desarrolla en la parte superior del cilindro encima donde los anillos se tallan y se gastan. El carbón también se junta en esta área para crear una región de un diámetro más pequeño de la perforatión del cilindro. Rocker arm  Pivots that transfer the motion of the pushrods or followers to the valve stem. Balancín  Un punto pivote que transfiere el movimiento de las levantaválvulas o de los seguidores al vástago de la válvula. Rod aligner  A rod aligner measures connecting rod twist and bend. Ajustador de la biela  Un ajustador de la biela mide la torcedura y doblez de la biela. Rod honer  A machine that hones (precision scratches) the ­connecting rod. Pulidora de bielas La pulidora de bielas es una máquina que pule (marcas de precisión) las bielas. Safety Data Sheet (SDS)  A sheet that contains detailed ­information concerning hazardous materials. The SDS must be maintained by the employer. Hoja de datos de seguridad (SDS)  Es una hoja que contiene información detallada sobre materiales peligrosos. El empleador debe encargarse del mantenimiento de la SDS. Safety glasses  Safety glasses have lenses that resist breaking and protect the eyes from airborne objects or liquids. If you wear prescription glasses, wear safety goggles that will securely fit over your glasses. Gafas de seguridad  Las gafas de seguridad tienen lentes resistentes a la rotura y protegen los ojos de los objetos o los líquidos que están en suspensión en el aire. Si usted usa lentes recetados, use antiparras de seguridad que se ajusten bien por encima. Safety goggles  Safety devices that provide eye protection from all sides. Goggles fit against the face and forehead to seal off the eyes from outside elements. Gafas de seguridad  Proporciona la protectión a los ojos de todos lados siendo que quedan apretados contra la cara y el frente para formar un sello para los ojos contra los elementos exteriores.

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Scale  The distance of the marks from each other on a measuring tool. Escala  La distancia entre las marcas en una herramienta de medir. Scan tool  A scan tool communicates with the powertrain ­control module to display diagnostic trouble codes and engine data. Herramienta de análisis  Una herramienta de análisis se comunica con el MCM (modulo de control del motor) para mostrar códigos de problemas de diagnóstico y datos del motor. Seat concentricity  Seat runout or concentricity is a measure of how circular the valve seat is in relation to the valve guide. Concentricidad de alojamiento  El alcance de alojamiento o concentricidad es la medida de cuán circular es el alojamiento de la válvula con relatión a la guía de la válvula. Seat pressure  Term that indicates spring tension with the spring at installed height and the valve closed. Presión del asiento  Un término que indica la tensión del resorte en su altura de instalación con la válvula cerrada. Self-tapping insert  A self-tapping insert provides a new thread when installed in an opening with damaged threads. Inserto rosea cortante  Un inserto rosea cortante proporciona una nueva rosea cuando se instala en una abertura con enroscado dañado. Sizing point  The location the manufacturer designates for ­measuring the diameter of the piston to determine clearance. Punto de calibración  El lugar indicado por el fabricante para efectuar las medidas del diámetro del pistón para determinar la holgura. Skirt  The piston skirt is the area from the lowest ring to the ­bottom of the piston. Bisel  El bisel del pistón es el área desde el anillo inferior hasta el fondo del pistón. Sleeving  The process of boring the cylinder to accept a sleeve. Sleeving is used to restore the cylinder bore to its original size. Encamisado  Es el proceso de perforación del cilindro para que acepte una camisa. El encamisado se utiliza para restaurar el diámetro del cilindro a su tamaño original. Small end  The end of the connecting rod that accepts the piston pin. Extremo menor  El extremo de la biela que acepta el pasador del pistón. Small-hole gauge  An instrument used to measure holes or bores that are smaller than a telescoping gauge can measure. Calibre de taladros chicos  Un instrumento que se emplea para medir los agujeros o taladros que son demasiado pequeños para medirse con un calibrador telescópico. Spring free length  The height the spring stands when not loaded. Longitud libre del resorte  La altura del resorte cuando no tiene carga. Spring shims  Components used to correct installed height of the valve spring. Spring shims are used to correct for machining tolerance. Chapas de relleno  Los componentes que se emplean para ajustar la altura de instalación del resorte de la válvula. El sobreespesor del maquinado se puede ajustar por medio de estas chapas. Spring squareness  Refers to how true to vertical the entire spring is. Escuadrado del resorte  Refiere a si la positión del resorte entero esta en linea recta al vertical.

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700

Glossary

Starter quick test  The starter quick test will isolate the problem area; that is, if the starter motor, solenoid, or control circuit is at fault. Prueba rápida de encendido  La prueba rápida de encendido aislará el área problemática; esto es, si tiene falla el motor de encendido, el solenoide o el circuito de control. Steam cleaners  A pressure washer that uses a soap solution, heated under pressure to a temperature higher than its normal boiling point. The superheated solution boils once it leaves the nozzle as it shoots against the object being cleaned. Limpiadoras de vapor  Una limpiadora a presion que utiliza una solutión de jabón, calentado bajo presión a una temperatura mós elevada de su punto de ebullitión. La solutión sobrecalentada hierve al salir de la boquilla projectada hacia el objeto para limpiar. Straight time pay  Straight time pay means that you are paid for every hour you are physically at work, regardless of your productivity. Pago por el número de horas acostumbrado por un período de trabajo  El pago por el mimero de horas acostumbrado por un periodo de trabajo significa que se paga por cada hora que se esta fisicamente en el trabajo, sin reparar en la productividad. Sulfuric acid  A corrosive acid used in automotive batteries. Ácido sulfúrico  El ácido sulfúrico es un ácido corrosivo que se usa en las baterías de automóviles. Supercharger  A belt-driven device that forces more air into the cylinders. Sobrealimentador  Un sobrealimentador es un dispositivo manejado por una banda que fuerza mas aire hacia los cilindros. Surface grinder  A surface grinder may be used to machine ­cylinder surfaces. Afiladora de superficies  Una afiladora de superficies puede usarse para tornear las superficies del cilindro. Tailpipe  The tailpipe conducts exhaust gases from the muffler to the rear of the vehicle. Tubo de escape  El tubo de escape conduce los gases de emisión del mofle hacia la parte posterior del vehículo. Tap  A tool used to repair or cut new internal threads. Macho  Una herramienta que sirve para reparar o cortar las ­roscas interiores nuevas. Taper  The difference in diameter at different locations in a bore or on a journal. Conicidad  La conicidad es la diferencia en diámetro en diferentes lugares en un orificio o en una muñequilla. Telescoping gauge  A precision tool used in conjunction with outside micrometers to measure the inside diameter of a hole. Telescoping gauges are sometimes called snap gauges. Calibrador telescópico  Una herramienta de precisión que se emplea junta con los micrómetros exteriores para medir los diámetros interiores de un agujero. Tambien se llaman ­calibradores de brocha. Thermal cleaning  Thermal cleaning relies on heat to break the dirt and grease from a part. Limpieza térmica  El método térmico de limpieza es el que utiliza el calor para eliminar la suciedad y la grasa de una pieza. Thread insert (hell-coil)  A device that allows for major thread repairs while keeping the same size fastener. Inserto prerescado (heli-coil)  Un dispositivo que permite las reparaciones completas de las roscas manteniendo los retenes del mismo tamaño.

Throating  Machining process using a 60-degree stone to narrow the contact surface. Rectificación  Un proceso de rebajar a máquina empleando una muela de 60 grados para disminuir la superficie de contacto. Thrust bearing  A bearing on the crankshaft that is used to ­control the amount of wear when the crankshaft moves back and forth. Cojinete de empuje El cojinete de empuje es un cojinete en el cigüeñal que se utiliza para controlar el nivel de desgaste cuando el cigüeñal se mueve hacia atrás y hacia adelante. Topping  Refers to the use of a 30-degree stone to lower the contact surface on the valve face. Despunte  Refiere al use de una muela de 30 grados para rebajar al superficie de contacto en la cara de la válvula. Torque plates  Metal blocks about 2 inch thick that are bolted to the cylinder block at the cylinder head mating surface to prevent twisting during honing and boring operations. Chapas de torsión  Los bloques de metal midiendo unas dos pulgadas de grueso empernados al monoblock en la superficie de contacto de la cabeza del cilindro que previenen que se retuerce durante las operaciones de esmerilado y taladreo. Torque wrench  A precision measuring tool that is used to ­connect to a socket and provide a measurement of fastener torque. Llave de tuercas para par La llave de tuercas para par es una herramienta de medición de precisión que se usa conectada a un tomacorriente y que mide el par de torsión. Torque-to-yield  A bolt that has been torqued to its yield point can be rotated an additional amount without any increase in clamping force. When a set of torque-to-yield fasteners is used, the torque is actually set to a point above the yield point of the bolt. This assures that the set of fasteners will have an even clamping force. De torsión a rendimiento  Un tornillo que se ha torcido hasta su punto de rendimiento puede girarse un poco más sin aumentar su fuerza de apriete. Cuando se usa un juego de sujetadores de torsión a rendimiento, la torsión se asienta a un punto encima del punto de rendimiento del tornillo. Esto asegura que la fijación de los sujetadores tendra una fuerza de sujeción más pareja. Total indicator reading (TIR)  The total movement of the dial indicator (above and below zero) is the total indicator ­reading (TIR). Lectura total del indicador  El movimiento total del indicador graduado (encima y por debajo de cero) es una lectura total del indicador. Turbocharger  A device that is driven by exhaust pressure and that forces air into the cylinders. Turboalimentador  El turboalimentador es un dispositivo al que lo impulsa la presión de emisión y que fuerza aire hacia los cilindros. Undersize bearing  Bearing with the same outside diameter as standard bearings but constructed of thicker bearing material in order to fit an undersize crankshaft journal. Cojinete de dimensión inferior  Un cojinete que tiene el diámetro exterior del mismo tamaño que los cojinetes normales pero que se ha fabricado de una material más gruesa para que puede quedar en un muñón de cigüeñal más pequeño. United States Customary (USC)  United States Customary (USC) measuring system is commonly referred to as the English system.

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Glossary Acostumbradas en EU  El sistema de medidas acostumbradas en EU comúnmente se refiere como el sistema inglés. Vacuum gauge  Designed to read intake manifold vacuum. Medidor de vacío  Diseñado para leer el vacío del múltiple de admisión. Valve guide  A part of the cylinder head that supports and guides the valve stem. Guía de válvula  Una parte de la cabeza del cilindro que apoya y guía al vástago de la válvula. Valve guide bore gauge  Instrument that provides a quick ­measurement of the valve guide. It can also be used to measure taper and out-of-round. Verificador del calibrador para la guía de válvula  Un instrumento que provee una medida rápida de la guía de la válvula. Tambien puede servir para medir lo cónico y lo ovulado. Valve seat runout gauge  Instrument that provides a quick ­measurement of the valve seat concentricity. Calibrador de la excenticidad del asiento de la válvula  Uninstrumento que provee una medida rápida de la ­concentricidad del asiento de la válvula. Valve spring tension tester  Device used to measure the open and closed valve spring pressures.

Probador de tensión del resorte de válvula  Un dispositivo que se emplea en medir las presiones de los resortes de las válvulas en la posición abierta o cerrada. Valve stem height  The height of the valve tip as measured from the base of the head to the top of the valve tip. Altura del vástago de la válvula  La altura del vastago de la válvula es la altura del punto de la válvula como se mide desde la base de la cabeza hasta la parte superior de la punta de la válvula.

Valvetrain clatter  A light tapping noise from the top of the engine, associated with wear of valve-related components.

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Matraqueo del tren de la válvula  El matraqueo del tren de la válvula es un ruido ligero de golpeteo de la parte superior del motor, asociado con el desgaste de los componentes relacionados con la válvula. Vernier calipers  Calipers that use a vernier scale which allows for measurement to a precision often to twenty-five times as fine as the base scale. Pie de rey  Los calibres que emplean una escala vernier permitiendo una medida precisa de diez a veinticinco veces más finas que la escala fundamental. Warranty repair  A warranty repair means that the manufacturer reimburses the shop for the parts and labor to make a repair. Reparación de garantía  Una reparación de garantía significa que el fabricante le reembolsa al taller las partes y el trabajo para realizar una reparacion. Waste gate  A valve that opens to bypass some exhaust around the turbine wheel to limit turbocharger boost pressure. Válvula de expulsión  La válvula de expulsión es una válvula que se abre para desviar una poca emisión alrededor del volante de la turbina para limitar la presión de empuje del turboalimentador. Wet sleeves  Replacement cylinder sleeves that are surrounded by engine coolant. Camisas húmedas  Las camisas de repuesta del cilindro que se rodean por el fluido refrigerante del motor. Workplace Hazardous Materials Information Systems (WHMIS)  Workplace Hazardous Materials Information Systems list information about hazardous materials. Sistemas informativos de materiales peligrosos en el centro de trabajo  Los sistemas informativos de materiales peligrosos en el centro de trabajo tienen unalista con informatión sobre materiales peligrosos. Z-87.1  ANSI-established standard for safety glasses. Z-87.1  Norma ANSI para las gafas de seguridad.

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INDEX

Page numbers followed by “f ” indicate figure.

A Abrasive cleaning, 17 Absorbed Glass Mat (AGM) battery precautions, 141–142 Aerobic sealers, 288 Air cleaner (job sheet), 331–332 Air cleaner service, 300–302 Air filter, 300f, 301f replacement of, 300–301, 302f Airflow restriction indicator, 301, 301f Align honing, 82, 555–556 Aligning bars, 67 Alignment, 82 acceptable, 549 camshaft bore, 398, 399f crankshaft bore, 67 fixture, rod, 604 main bearing bore, 548–549 problems, preventing, 82 procedure for checking, 550 Allen wrenches, 278–279 Aluminum hydroxide deposits, 168 Anaerobic sealers, 288 Antifreeze checking condition of, with digital voltmeter, 167 content in coolant, testing, 162 ASE Certification, 89–91 Automotive Engine Rebuilders Association (AERA), 353, 561

B Backlash, 496 checking for, 539 Balance shafts bearings, measurement, removal, and replacement, 564–565 installing OHV, 613–615 Base circle, camshaft, 445 Basic testing, 117–124 engine component identification (job sheet), 127–128 Batteries inspection of, 137–138 need for caution when charging, 23

702

safety, 136 testing, 136–142, 142f (See also Specific tests) Battery capacity test, 140, 141f. See also Capacity test Battery case test, 141 Battery conductance test, 138–139. See also Conductance test Battery terminal voltage drop test, 139 Bearings, 151, 588–591. See also Camshaft bearings balance shafts, 564–565 bore alignment (job sheet), 585–586 and crankshaft, installing (job sheet), 651–653 failure analysis, 588–591 inspecting crankshaft, 588–591 inspecting wear patterns (job sheet), 643–644 installing, 620 oversized, 550 pilot, 616, 616f prelubricating turbocharger, 324 removers and installers for camshaft, 79 selection chart, 617, 618f undersized, 588 wear patterns, 643–644 Bell housing, 256 Bellmouthing, 400f, 401 Belt surfacers, 77 Belt tension gauge, 49, 50f Big-end bores, 600, 601 resizing, 603–606 Black smoke, 241–242 Blowby, 177 out-of-round, 548 Blue smoke, 236–238, 317, 318, 472, 472f Bolts flywheel, 360 torque-to-yield, 70 Boost pressure low turbocharger, effects of, 320 (job sheet), 339–340 testing, 320 typical procedure for (photo sequence), 321 Boring, 82 Bottom-end knock, 255–256 Broach, 77 Bushings, 601, 612

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index

C Calipers, 55–56, 59 Camshaft base circle, 445 bore alignment, 398, 399f on DOHC engine, 442–443 heel, 444, 445 with high duration, 446 inspecting, 444–447 (job sheet), 483–484 installing (job sheet), 649–650 -in-the-block engines, timing mechanism replacement in, 503 nose, 444, 445 OHV, 649–650 removing, 539 and replacing on OHC engine, 442 and replacing on OHV engine, 442 Camshaft bearings measurement, removal, and replacement of, 564–565, 565f removers and installers, 79 Camshaft end play measuring, 614 and bearing clearance, on DOHC engine, 444 Camshaft position actuators, 515 Capacity test, 140–141, 141f Carbide seat cutters, 415–416 Carbon monoxide (CO), 20 Carrying, safety precautions, 6 Case studies, 24, 97, 124, 186, 258, 288, 289, 327, 369, 419, 475, 520, 570, 637, 669 Casting plugs, 174–176 Catalytic converter, 314, 315f testing, 314–316 Caustic chemicals, 4 Challenges to technician identifying repair area, 117–118 lack of communication (customer), 117 service history, 118 Chassis dynamometer, 72 Chassis ear machine, 121, 122f Chemical cleaning, 16 Chemical combustion tester, 240 Chemical thread repair, 280 Cherry-picker, 15. See also Engine hoist Chisel fasteners, 276 Cleaning equipment safety, 16–19 Clothing, safety precautions, 4–5 Combustion gases, leaks of, 239 improper, 242–244

703

Combustion chamber coolant in, 239, 240f signs of potentially serious trouble in, 233 Compensation, 87–89 Compressed air guidelines for working with, 10 tools that use, 10 Compressed air equipment safety, 10 Compressed natural gas (CNG) vehicles servicing, 661–664 (job sheet), 673–674 warning labels, 662f Compression of air-fuel mixture, 44 leaks, 45, 397 low cylinder, 318, 320 test, (job sheet), 269–270 Compression gauges, 44–45 types of, 44–45 Compression testers, 44–45, 245, 245f. See also Compression tests Compression tests, 244–249. See also Compression testers analyzing results of, 245, 248, 249f cranking, 244–245 performing (job sheet), 269–270 photo sequence, 246 running, 247–249 wet, 246–247 Computers, 93f Conductance test, 138, 139 Connecting rods, 83–85, 623–625 cap bolt replacement, 604 failures and causes, 602 inspecting, 591–603 (job sheet), 639–642 installing, 623–625 (job sheet), 655–657 reassembly, 608 straightening, 604 Connectors, labeling, during engine removal, 344f Coolant checking antifreeze content in, 162 in combustion chamber, 245 flushing, 168–169 leaks, 180–184 level, checking, 162 premixed with water, 168 temperature switch/sensor circuit testing (job sheet), 219–220 test, drain, and refill (job sheet), 209–210 Coolant hydrometer, 47–48, 48f Coolant refractometer, 48, 49f Coolant test strips, 48, 49f

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

704

Index

Cooling system, 161–174 combustion gases leaking into, 239 components, 162 testing of, 169 draining, 165–167 exhaust gases in, 239 fan inspection (job sheet), 223–224 filling, 167–168 important parts of, 174–176 inspection, 162–163 leak diagnosis (job sheet), 213–214 maintenance, 162 photo sequence, 181–182 pressure tester, 48, 48f temperature warning system, 184–185 testing and service, 161–162 Core plugs, 175, 175f, 381 installation of, 569–570 removal of, 542–545 Corrosion, 357f Cranking compression test, 244–245 photo sequence depicting, 246 steps for performing, 244–245 Crankshaft balancers, 83 bearings failure analysis, 588–591 inspecting, 588–591 grinder, 83 inspecting, 551 installing, 616–623 (job sheet), 673–674 typical procedure for, 620 journals, measuring, 553 peening, 569, 569f polishers, 83 preventing, 543f pulley, removal of, 355, 498 reconditioning, 567–568 equipment for, 83 removal, 355, 498 straightening, 568–569 thrust, 553, 554f warpage checking, 545–546 Crankshaft end play, 256, 257f Crankshaft pulley (job sheet), 425 Crate engines, 91 Current draw, 147 Current draw test, 147–148 Cylinder boring, 79

finding malfunctioning, 228 hone, 80–82, 81f with low cranking compression, 247, 249 out-of-roundness, 546 oversized, 546 reconditioning, 567–568 wear, 546 (See also Cylinder walls) Cylinder block assembly cylinder reconditioning, 556–559 line boring and align honing, 555–556 resurfacing deck, 556 servicing, 555–564 sleeve installation, 562–563 Cylinder block inspection, 544–550 checking for deck warpage, 545–546 checking main bearing bore alignment, 548–549 engine block bore measurements, 549 inspecting and measuring cylinder wall wear, 546–548 Cylinder bore dial gauges, 65–66 Cylinder boring, 556–558 Cylinder head assembly in OHC engine, 461–463 crack detection (job sheet), 431–432 disassembling, 387–393 (job sheet), 429–430 typical procedure for, 391–392 equipped with inserts, 402 inspection, 397–403 installing, 468–469, 471, 626–628 checklist for, 626–628 procedure for installing valves into, 459 reassembly, 457–463 (job sheet), 491–494, 649–650 installed spring height, 457–458 installing valve stem seals, 458–459 reconditioning equipment, 72–85 removal, 382, 535–536 (job sheet), 427–428 from OHC engine, 385–387 from OHV engine, 382–385 procedure for, 535–536 resurfacing, 405–406 straightening aluminum, 404–405 valve removal, 388–393 warpage (job sheet), 433 Cylinder head gasket, installation of, 284, 285f Cylinder leakage test, 45, 249–255 performing (job sheet), 273–274 photo sequence depicting, 253–254 steps for, 250–252 Cylinder leakage tester, 45. See also Cylinder leakage test

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index Cylinder walls boring, 557–559 deglazing, 556 inspecting and measuring (job sheet), 583–584 wear on, 546 measuring wear on (job sheet), 111–112 reconditioning methods for, 556–559 sleeving, 561–562

D Deck resurfacing, 556 warpage checking for, 545–546 measuring (job sheet), 579–580 Detonation, 242 common causes of, 242–243 Diagnostic link connector (DLC), 43 Diagnostic tree, 97f Diagnostic trouble code (DTC), 44, 314, 315 Dial calipers, 57–59 reading (job sheet), 105 reading procedure, 58f Dial indicators, 64–65 reading (job sheet), 107 using, 65 Dies, 279 Diesel fuel, storage of, 22 Digital pyrometer, 315 Digital voltmeter, 167 DOHC engine inspecting and servicing rocker arms and shafts on, 453–454 measuring camshaft end play and camshaft bearing clearance on, 444 removing camshafts and rocker arms from, 442–443 Dry sleeves, 561 replacing, 563 Dry starts, 589 Duration, 444, 445f

E Ear protection, 5 Education, 85 Electrical discharge machining (EDM) process, 278 Emergency telephone numbers, 22 Engine(s) analyzers, 233–234 belt and system inspection (job sheet), 221–222 camshaft-in-the-block, 512

crate, 353, 355 cylinder leakage test (job sheet), 273–274 diagnostic tools, 42–52 disassembly, 540–544 preparation for, 534 installation remanufactured, 353–361 installation of, 361–365 lugging, 597 materials, identifying (job sheet), 297 measuring tools, 54–68 (See also Specific tools) mounting, on stand, 352, 354 noise diagnosis, 255–258 oil inspection (job sheet), 195–196 operating systems, diagnosing and servicing, 135–225 performance concerns, diagnosing, 227–274 preoiling, procedure for, 157 propane fueled, 659–660 rebuilding tools and skills, 39–116 repair, skills required for, 91–93 running compression test (job sheet), 271–272 safely lifting, 15–16 sensors, switches, and solenoids, 357, 357f smoking, 236–242 starting, at initial start-up and break-in, 365–369 that use mechanical followers, 466–467 with VVT systems, 515–520 Engine analyzers, 53–54 power balance testing using, 233–234 Engine assembly. See also Engine block completing, 630–637 guide for, 631, 632f sensors and switches mounted on, 636f Engine block. See also Engine block disassembly assembly, completing, 625–628 bore measurements, 549 components, cleaning, 543 crack detection (job sheet), 577–578 flushing, 168–169 installing accessory items that attach to, 635 preparation, 612–616 checklist for, 612 reconditioning equipment, 79 Engine block disassembly, 540–544 camshaft removal, 540 core and oil gallery plugs, 542–544 crankshaft removal, 542 (job sheet), 573–575 piston removal, 541–542 ring ridge removal, 540–541 Engine crane, 15. See also Engine hoist Engine dynamometer, 72

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

705

706

Index

Engine fasteners and torque specifications identifying (job sheet), 291–292 Engine hoist, 15, 349, 350f, 351 Engine installation, 361–365 front-wheel-drive vehicles, 362–364 (job sheet), 377–378 rear-wheel-drive vehicles, 364–365 Engine mounts inspect, remove, and replace (job sheet), 379 removal of, 349, 350f Engine removal, 347–351 front-wheel-drive vehicles, 347–351 (job sheet), 373–374 typical procedure for, 348–349 preparing for, 341–346 steps to complete in process of, 342–346 rear-wheel-drive vehicles, 351 (job sheet), 375–376 swap, and installation, 357, 358, 360f typical procedure for, 351, 352 Engine stand, 352, 352f securing engine, 534 Engine start-up and break-in, 365–369 final checks, 368 five-hundred-mile service, 368–369 initial, 366 priming lubrication system, 366 road test, 367 starting engine, 366–367 Environmental Protection Agency (EPA), 19 guidelines for hazardous waste, 19–20 toxic pollutants regulated by, 52 Equipment align boring, 82 block resurfacing, 82 cleaning, safety, 16–19 connecting rod and piston reconditioning, 83–85 crankshaft reconditioning, 83 cylinder head reconditioning, 72 resurfacing, 77–78 engine block reconditioning, 79 grinding, guidelines for, 412–414 special reconditioning tools and, 72–85 valve guide renewing, 74–75 Exhaust gas analyzers, 52 four-gas, 183 Exhaust gas recirculation (EGR) valve, 358 Exhaust system components, replacing, 312

gaskets and seals, replacing, 313–315 inspection, 311 and test (job sheet), 335–336 manifold and pipe servicing, 312 service, 311–316 Extractor, 276, 277f steps for using, 278 Eye protection, 2–4

F False guide, 409, 409f Fan(s) inspection of, 169–172 shroud, 171, 172f, 174 Fasteners. See also Specific Types of Fasteners loosening rusted (job sheet), 293–294 Feeler gauges, 54–55 used as “go, no-go” gauges, 397 using, 55 (job sheet), 103–104 Fire extinguishers, 22 Flat rate pay, 88 Flex fans, 170 Flex plates, 555 Floor jacks, 13, 14f Flywheel bolts, 360 holder, 355–356, 356f inspecting, 554–555 Front pipe, 311, 313, 313f Front-wheel-drive (FWD) vehicles engine removal, 347–351 typical procedure for, 348–349 installation of engine, 362–364 undercarriage installation procedures, 363 upper engine procedures, 363–364 Fuel air-, mixture, compression of, 44 compressed natural gas, 660–662 diesel, 22 under extremely high pressure, 659 fuel-fouled spark plugs, 232 gasoline, 22 natural gas, 673–674 propane, 659–660 Fuel control valve, 660 Fuel pressure gauges, 51, 51f Fuel pressure regulator, 241 Full-floating piston pins, 593 Fusible link, 97f, 146

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index

G Gallery plugs, 381 removal of, 543, 543f Gases combustion, 239 escape of, during charging of battery, 21 exhaust, 311 Gaskets cylinder head, 284, 285f installation of, 284 oil pan, 285 procedure for removing and replacing intake manifold, 308–309 replacing exhaust system, 313–315 steps for preparing to replace, 284 Gasoline, storage of, 22 Gauges belt tension, 49, 50f cylinder bore dial, 65–66 feeler, 54–55, 397, 398f fuel pressure, 51, 51f oil pressure, 49, 49f out-of-round, 67, 67f small-hole, 64 telescoping, 64 torque angle, 69 vacuum, 45–46, 53, 304 valve guide bore, 65 valve seat runout, 65 General Motors, 149 Grinding equipment guidelines, 412–414 journal, 569 Grinding stones, 75

H Hair, safety precautions, 5 Hand tools safety steps for, 6–7 special, 68–71 Harmonic balancers, 356f inspecting, 554–555 removal of, 355–356, 356f, 537 (job sheet), 425 Hazardous materials, 18 proper handling of (job sheet), 31–32 Hazardous waste, 19–20 Head, piston, 594, 603f Head resurfacing equipment, 77–78 Heel, camshaft, 444, 445

707

Helical inserts, 280, 282 Hoists, 10, 11f. See also Lifts typical procedure for lifting vehicle on, 14 Honda Civic hybrid, 668–669 Honing, 79, 82, 82f cylinder walls, 558–559 typical procedure for, 558–559 plateau, 561 Horsepower, 72 Hoses broken or disconnected, 302 Hybrid electric vehicles (HEVs), 663–665 Honda Civic hybrid, 668–669 Toyota Prius, 664–668 warranties, 669 Hydraulic lifters, 448, 449f, 464–466 Hydraulic presses, 9, 9f Hydrostatic lock, 142

I Idler pulleys, 172, 173f Ignition systems coil-on-plug, 234 Impact screwdriver, 540 Improper combustion, 242–244 Infrared testers, 52 Initial inspection and service writing, 117–124 Insert guides, 408 Insert valve seats, 409–410, 411f Intake manifold, 358, 359f gasket, procedure for removing and replacing (photo sequence), 308–309 removal procedure, 306–308 service, 305–311 vacuum, 45, 46 Intake system air cleaner, 300–301 diagnosis and service, 299–340 intake manifold, 305–311 vacuum system, 302–303 Integral guides, 409 Integral valve seats, 410–411 Interference angle, 412 Interference fit, 537 Internet, 93

J Jack and jack stand safety, 13–15 Jack stands, 13 Jet valves, 155

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

708

Index

Jewelry, safety precautions, 5 Journals, 446, 447f grinding, 569 inspecting, 553 measuring crankshaft, 553 polishing, 551

K Keepers, installing, 460–461 Key-locking inserts, 280, 283 Knock sensor (KS), 243 Knurling, 74–75, 75f typical procedure for, 406–408 kPa metric kilopascals, 44

L Land, piston, 594 Lash adjusters, inspecting (job sheet), 485–486 Leak-down, 448, 449f test, performing, 448 Leaks combustion gas, into cooling system, 239, 240f compression, 45, 397, 612f coolant, 180–184 detection of, using cranking compression test, 244, 245f detectors for, 46–47 diagnosis of, 176–184 in exhaust system, likely spot to find, 313 intake manifold gasket, 306 oil, 176–177 use of smoke leak detector to find, 304, 305f vacuum, 46, 304 methods for testing, 304, 305f Lifters disassembling, 449 hydraulic adjusting adjustable, 463–466 internal components of, 449, 449f inspecting, 447–449 (job sheet), 485–486 mechanical or solid, adjusting, 463 roller, 448–449 Lifting engine, 15–16 safety precautions, 6 vehicle (job sheet), 35–38 typical procedure for, 14 Lifts. See also Hoists engine, safety for, 15–16 safety measures for, 10–13

Lift safety, 10–13 Line boring, 549, 555–556 Lineman’s gloves, 668 Liners, 408 Liquid petroleum gas (LPG) vehicles, 659, 660 (job sheet), 673–674 Liquids, volatile, 22 Load test, 138 Lobe lift, 446, 446f, 447f LPG, 659–660 Lubrication system important parts of, 174 maintenance, 156–158 priming, for start-up and break-in, 366 testing and service, 151–152, 161–162 Lugging, 597

M Machine shop services, 403 Machinist’s rule, 55, 56 Magnafluxing, 544 Main bearing bores checking alignment of, 548–549 typical procedure for, 550 resizing and realigning, 555 Main bearings installing, 620 (job sheet), 651–653 guide list for, 619–622 wear on, 590f Major repair indication blue smoke, 120f Malfunction indicator light (MIL), 44, 314 Manual shut-off valve, 661, 661f Material Safety Data Sheets (MSDS), 18 Measurement of length, 42 of mass, 42 units of, 40–42 valve, 419 of volume, 42 Mechanical followers, adjusting, 466–467 Meter (m), 41 Metric Conversion Act (1975), 41 Metric system, 41 common equivalents between USC system and, 41 common prefixes in, 42 Microinch, 78 Micrometers, 59–60 reading, 60–61 typical procedure for, 63

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index Minor thrust side, 607 Misfire, 44, 52 corrosion as cause of, 357f Muffler, 311

N National Institute of Automotive Service Excellence (ASE), 89 blue seal of excellence, 23 certification program, 89–91 Natural gas, 661 Noid lights, 52 Noises, engine, 255–258 bottom-end knock, 255–256 diagnosing (job sheet), 261–262 piston pin knock, 256–257 piston slap, 257 timing chain clacking or rattling, 257 use of stethoscope to detect, 50, 50f valvetrain clatter, 257–258 Nose, camshaft, 444, 445 Nut splitter, 276, 277f

O OBD II vehicles. See On-board diagnostic (OBD) system Occupational Safety and Health Administration (OSHA), 18 OHC engine with balance shafts, timing chain replacement on, 504–507 bearing bore alignment, 404–405 camshaft bearing wear in, 398 cylinder head assembly, 460f, 461–463 cylinder head removal from, 385–387 removing and replacing camshaft on, 442 replacing timing belt on, 510–511 timing chain replacement on, 504–507 typical procedure, 629 valve timing components, installing, 628–629 valvetrain installation, 629–630 OHV engine camshaft removal from, 442 cylinder head removal from, 382–385 inspecting and servicing valvetrain components on, 447–450 installing camshafts and balance shafts on, 613–615 removing and replacing camshaft on, 442 valve timing components, installing, 628 valvetrain installation, 629 valvetrain timing (job sheet), 525 Oil change intervals, improper, 387 consumption, 161, 242 consumption due to worn valve seals, 472, 472f and coolant consumption diagnosis (job sheet), 267–268

709

coolant mixed with, 239 jet valves, 155–156 leaks, 176–177 diagnosis of (job sheet), 205–206 from valve cover gaskets, 285 level and condition, 158 pressure, causes of low, 564 Oil gallery plugs, 381 installation of, 569–570 Oil pan gaskets, 631f installation of, 285 replacing (job sheet), 295 Oil pressure gauge, 49, 49f Oil pressure test, 151. See also Oil pressure testing Oil pressure testing, 151–152. See also Oil pressure test job sheet, 203–204 switch/sensor and circuit (job sheet), 207–209 Oil pump, 151 crank-driven, 538f installing, 626, 627 service, 152–153 typical procedure for disassembly and inspection of rotor-type, 153–154 On-board diagnostic (OBD) system, 43, 242, 243, 314, 315 On-car service, 472–475 valve seal replacement, 472–474 valve spring replacement, 475 Open circuit voltage test, 140 Open pressure, 455, 456, 456f O-rings, 167, 174f, 359f, 390, 626 installing, 459 Out-of-round gauges, 67, 67f Out-of-roundness, 546 Outside micrometers, 399, 400 using (job sheet), 109–110, 435–436 Overboost, 300 Overlap, 444 Oversized bearings, 588 Oxygen sensor, 241

P Particulates, 21 Peening, 569, 569f Personal safety, 2–5 warnings, 5 Pickup tube, 155, 626 Pilot bearings, 616, 616f Pilot bushings, 551 Pin boss, 595 Pin drift, 83 Pin hole machines, 84

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

710

Index

Piston(s) assembly service, 603–612 inspecting, 591–603 (job sheet), 639–642 installing, 608–612, 623–625 (job sheet), 645–647, 655–657 chart, wear analysis, 598 measuring, 596–597 reassembly, 608 typical procedure for, 623–625 wear analysis, 597–598 oversizes, common, 546 reconditioning equipment, 82–84 removal of, 541–542 Piston pin knock, 256–257 Piston pins, 83 checking wear on, 592 full-floating, 593 inspecting, 599–600 press-fit, 593, 594f removing, 592–594 Piston rings inspecting, 599 installing, 608–612 (job sheet), 645–647 removal and groove cleaning, 592 Piston skirt, 594, 595 Piston slap, 257 Plastigage, 68, 68f Plateau honing, 561 Plugs, 174–176, 381 Pneumatic tools, 10 Polishing, 551 Pollutants, 21, 52 Poppet valves, 394 Positive crankcase ventilation (PCV) system, 177 Power balance testing, 228 analyzing results of, 235 analyzing spark plugs and performing (job sheet), 263–265 manual, 234–235 using engine analyzer or scan tool, 233–234 Power tools, 7–9 Powertrain control module (PCM), 43 Preignition, 242 common causes of, 242–243 Prelubrication, 324 of engine after oil change, 324 Press-fit piston pins, 593, 594f, 608 Pressure plate, 591 Professionalism, 86–87 Professional technicians ASE Certification, 89–91 compensation, 87–89

education, 85 professionalism, 86–87 skills required for engine repair, 91–93 working as, 85–92 Profilometers, 78 Propane, 659–660 Prussian blue, 418 psi (pounds per square inch), 44 Purge solenoid, 358 Pushrods, inspecting, 449–450

Q Quick disconnect fittings, 307, 307f

R Radiator, 162 flushing, 168–169 removal, 172–174 replacement (job sheet), 211–212 Rear-wheel-drive (RWD) vehicles camshaft removal with engine in vehicle, 442 engine removal, 351 installation of engine, 364–365 Relief valve, 153, 155 Remanufactured engines, installing, 353–361 Repair order (RO), 119 3Cs, 119 customer’s concern, 119 legal document, 119 vital information, 119 Resource Conservation and Recovery Act (RCRA), 17 Restricted exhaust, 316 Ridge reamers, 79, 80f Right-to-Know laws, 18 Ring compressors, 71 Ring end-gap grinders, 84 Ring expanders, 71 Ring groove cleaners, 71 Ring ridge, 540 Rings. See also Piston rings damaged compression, 611f installing, 608–612 marking of directional, 611 tools for, 84 Road test, for initial start-up and break-in, 367 Rocker arm geometry, 453 correcting, 453 Rocker arms. See also Rocker arm geometry adjustable, adjusting valves using, 467–471 inspecting (job sheet), 487–488 inspecting and servicing, 450 shaft-mounted, 451, 452f

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index and shafts, DOHC engine, 453–454 stud-mounted, 452–453, 452f, 453f removing, on DOHC engine, 442–443 replacing studs of, 450–457, 451f Rod aligners, 84, 85f Rod cap grinders, 84 Rod heaters, 85 Rod honers, 84, 85f Roller lifters, 448–449 Room-temperature vulcanizing (RTV) liquid gasket makers, 288 Rule 66 (California) for clean air, 17 Running compression test analyzing results of, 248, 249f performing (job sheet), 271–272 steps for performing, 248

S Safety cleaning equipment, 16–19 compressed air equipment, 10 concerns regarding cylinder head valve removal, 388 engine lift, 15–16 guidelines for toxic chemicals and solvents, 19 hand tool, 6–7 jack and jack stand, 13–15 lift, 10–13 lifting and carrying, 6 mounting engine on stand, 352f photo sequence, 354 performing repairs on CNG vehicles, 660 personal, 2–5 power tool, 7–9 servicing HEV vehicles, 663–664 shop practices and, 1–38 survey, shop (job sheet), 27–29 vehicle operation, 20–21 work area, 21–23 Safety glasses, 2, 3f Safety stands, 13 Salvage (flood) title, 123, 123f Scales, 55 on machinist’s rule, typical, 55, 56f Scan tool diagnostics, 185–187 Scan tools, 43–44 power balance testing using, 233–234 using, retrieve engine codes (job sheet), 225 Sealants room-temperature vulcanizing, 288 using, 288 Seals installation of, 287–288 replacing exhaust system, 313–315

sign of worn turbocharger, 317 valve stem, 390 (See also O-rings) Seat concentricity, 402 Seat cutters, 76 carbide, 415–416 stone, 416, 417f Seat grinders, 75 Seat inserters, 76–77 Seat pressure, 456 Seat runout, 402, 403f Self-tapping insert, 283 Service information, 93–97 finding (job sheet), 113–114 inspection information, 95f layout, 94f manufacturers’ websites for, 93 referring to proper, 173 specification tables provided in, 96f table of contents for major component area of, 98f use of computers to retrieve, 94 Service repair order definition, 119 job sheet, 131–133 Service writer, 119 communication with customers, 119 responsibility of, 119 Shaft-mounted rocker arms, 451, 452f Shims, 149 adjusting mechanical followers with, 466–467 spring, 455 Shroud, fan, 171, 172f, 174 Sizing point, 596 Skirt, 594 Sleeving, 561–562 Small-end bores, 600 reconditioning, 607 Small-hole gauges, 64 Smoke black, 241–242 blue, 236–238, 317, 318, 472, 472f engine, 236–242 exhaust, 317, 318 white, 239–241 Solenoids, 357, 357f Solvents, safety guidelines for, 19 Spark plugs, 228–233 analyzing, and performing power balance test (job sheet), 263–265 reading, 231–233 removal and installation, 229–230 worn, 231f Spring free length, 455 Spring shims, 455

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

711

712

Index

Springs, installing, 460–461 Spring squareness, 454, 455f Sprocket inspection, 501 Starter. See also Starter motor; Starting system shimming, 149f testing (job sheet), 193–194 Starter motor. See also Starter; Starting system installation, 153 removal, 148–151 R & R, 150–151 Starter quick test, 146 Starting system. See also Starter starter motor problems, diagnostic chart used to determine, 149 testing, 146–148 tests and service, 142–151 troubleshooting, 142–147 Steam cleaner, 342 Stethoscopes, 50f, 50, 248 Stone seat cutters, 416, 417f Straight time pay, 88 Stud-mounted rocker arms, 452–453, 452f, 453f Studs, 392f Sulfuric acid, 21 Superchargers, 324–327 diagnosis, 325 installation of, steps for, 325–327 intercooler inlet and outlet tubes, 326f malfunction of, 300 mounting bolt location, 325, 326f removal of, steps for, 325–327 Surface grinders, 78, 78f

T Tailpipe, 311 Taper, 546 permissible amount of, 546 Tappets, 466f Taps, 279 Technician challenges to identifying repair area, 117–118 lack of communication (customer), 117 service history, 118 role’s of test driving, 118 Telescoping gauges, 64 Tensioner inspection, 501–502 Test driving (by technician) basic inspection and for service preparation (job sheet), 129–130 for engine concerns, 119–121

Thermal cleaning, 17 Thermostat diagnosing and replacing (job sheet), 217–218 testing, 169 Thermostat, testing, 169 Thread chasers, 279 Thread inserts, 280, 282, 283f types of, 280, 282–283 Thread repair, 275–284 photo sequence depicting, 281–282 Throating, 418, 420f, 421f Thrust bearing, 310 Timing belt inspection, 499, 500f (job sheet), 523–524 removal of, 537, 539f replacement, 507–511 on OHC engines, 510–511 snapped, 497f water pump driven by, 174 Timing chain guide inspection, 502 inspection, 498–499, 499f (job sheet), 523–524 noise, 257 replacement on camshaft-in-the-block engines, 512 engines with OHC and balance shafts, 513, 514 on engines with VVT systems, 515–520 (job sheet), 523–524 on OHC engine, 504–507 tensioners, 516f Timing gear inspection, 500–501 replacement on camshaft-in-the-block engines, 512 Timing mechanism disassembly, 505f, 536–539 jumped or broken diagnosing, 497–498 symptoms of, 497–498 replacement, 503–504 reuse versus replacement decisions, 502 service, 495–520 sprocket inspection, 501 tensioner inspection, 501–502 timing belt inspection, 499, 500f timing chain guide inspection, 502 timing chain inspection, 498–499, 499f timing gear inspection, 500–501 symptoms of worn, 496–497 TIR (total indicator reading), 552 Tools. See also Hand tools engine diagnostic, 42–52

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Index engine measuring, 54–68 and equipment, special reconditioning, 72–85 exhaust system service, 312 pneumatic, 10 power, 7–9 quick disconnect fittings, 307, 307f tied rod end removal, 347, 348f Top dead center (TDC), 73 Topping, 418, 420f, 421f Torque angle gauge, 69 Torque plates, 82 Torque-to-yield fasteners, 70 Torque wrenches, 68–69 using, 69 Torquing, 68, 69, 155 Total indicator reading (TIR), 552 Toyota Prius, 664–668 Turbochargers, 317 diagnosis of, 317–324 guide for, 318 failures of, common, 318, 319 inspection, 320 component, 322–323 typical procedure for, and testing boost pressure, 321 installation and prelubrication, 323–324 malfunction of, 300 removal procedure for, 322 service, guide for, 318 system inspection (job sheet), 337–338 troubleshooting guide, 319f

U Underboost, 300 Undersized bearings, 588 United States Customary (USC) measuring system, 40 common equivalents between metric system and, 41

V Vacuum gauges, 45–46, 53, 304 Vacuum pumps, 46 Vacuum system diagnosis and troubleshooting, 302–303 leaks, 46, 304 diagnosing (job sheet), 333–334 problems, driveability symptoms related to, 302 tests, 304, 305f typical devices and controls, 303f Valve adjustment, 463–466 (job sheet), 489–490 intervals, 463 symptoms of improper, 464 typical procedure for, 468–470

Valve clearance, 467–471 (job sheet), 489–490 checking and adjusting, 630 Valve cover gaskets, replacement of, 285 photo sequence depicting, 286–287 Valve faces, 394, 394f Valve grinding equipment, 77 Valve guide bore gauges, 65 inspection, 399–402 measuring clearance, methods used, 399–400, 401f renewing equipment, 74–75 repair, 406–409 replacement, 408 worn, 472, 472f Valve inspection, 394. See also Valves inspecting valve head, 394–395 valve guide inspection, 399–402 valve seat inspection, 402, 403 valve stem inspection, 395–397 Valve rock method, 400, 401f Valves. See also Valve inspection adjusting, using adjustable rocker arms, 467–471 fitting, 417–419 installing, 458–459 measurement of, 419 poppet, 394 reconditioning, 412–414 reconditioning (job sheet), 439–440 refinishing, 414, 415f removal, 388–393 Valve seals replacing, 472–474 on the vehicle, 473–474 worn, 472, 472f Valve seat(s) cutters, 76 fitting, 417–419 grinders, 75 grinding (job sheet), 437–438 typical procedure for, 420–421 inserters, 76 inspection, 402, 403 reconditioned, 402 refinishing, 414, 415f using carbide seat cutters, 415–416 using stone seat cutters, 416, 417f replacement, 409–411 insert, 409–410, 411f integral, 410–411 Valve seat runout gauges, 65 Valve spring compressor, 73, 74f

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

713

714

Index

Valve springs, 454–457 inspecting, 455 inspection (job sheet), 481–482 open pressure, 455, 456, 456f replacement, 475 seat pressure, 456 Valve spring tension testers, 73, 74f, 456, 457f Valve stem grinding equipment, 77 height, 419 inspection, 395–397 oversized, 408 Valve stem seals installing O-ring, 459 positive stem, 458–459 umbrella-type, 459 replacement (job sheet), 479–480 Valve-stem-to-guide clearance (job sheet), 435–436 Valve timing components, installing, 628–630 Valvetrain clatter, 463 components installing, 628–630 inspecting and servicing, 442–447 inspecting camshaft, 444–447 measuring camshaft end play and bearing clearance, DOHC engine, 444 OHV engine, components on, 447–450 removing and replacing camshaft on OHC engine, 442 removing and replacing camshaft on OHV engine, 442 timing, (job sheet), 525 installation on OHC engine, 629–630 on OHV engine, 629 service, 441–475 Valvetrain clatter, 256–258 Valvetrain timing OHV (job sheet), 527 SOHC (job sheet), 529–530 Variable valve timing DOHC (job sheet), 531–532 Vehicle(s). See also Vehicle service lifting, 14 (job sheet), 35–38 LPG (job sheet), 673–674

operation safety, 20–21 servicing, 660–661 (job sheet), 673–674 Vehicle service alternative fuel and advanced technology, 659 CNG vehicles, 660–662 hybrid electric vehicles (HEVs) Honda Civic hybrid, 668–669 Toyota Prius, 664–668 LPG vehicles, 659–660 Ventilation, need for proper, 22 Vernier calipers, 55–56 Vernier scale, 56, 57f Vibrations diagnosing (job sheet), 261–262 reduction of torsional, 534 Volatile liquids, 22 VVT systems, 515–520

W Warning systems cooling system temperature, 184–185 diagnosis of, 184–186 engine oil pressure, 184 Warranty repair, 86 on HEV vehicles, 669 Wastegate, 320 Waste, hazardous, 19–20 Water pump removal of, 172–174, 538f replacing (job sheet), 215–216 Wet compression tests, 246–247 Wet sleeves, replacing, 563 White smoke, 239–241 Work area safety, 21–23 Workplace Hazardous Materials Information Systems (WHMIS), 18 Wrenches Allen, 278–279 torque, 68–69 Wrist pins, 83. See also Piston pins Writing service repair order, 119

Z Z-87.1 standard, 3

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300

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Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300