Modern diesel technology

Modern Diesel Technology Robert N Brady Vancouver Community College and HiTech Consulting Limited Prentice Hall Englewood Cliffs,New Jersey Columbus, Ohio Especially for Linda, Alanna, Alicia, Scott, Tracy and Adele! To all of the creative individuals who have allowed me to gain knowledge and skills from their benchmark experiences, and to the many motivated students, friends and SAE colleagues within the diesel and automotive industry who have shared their standards of excellence This book is a reflection of a diversity of backgrounds of truly remarkable people who provided me with their time and support I trust that the finished product meets your high standards and expectations About the Author Robert N Brady has been involved in the automotive, heavy-duty truck and equipment field since 1959, having served a recognized five year apprenticeship as both an automotive and heavy-duty truck and equipment technician He is a graduate of Stow College of Engineering in Glasgow, Scotland, with a degree in Mechanical Engineering Technology.He holds degrees both from the University of British Columbia, and the University of Alberta in Adult Education He is a certified automotive, commercial transport and heavyduty equipment technician His background experience includes positions as a shop foreman and service manager with Kenworth, fleet maintenance superintendent with North American Van Lines; factory service trainer for Canada, service representative, and sales application engineer with Detroit Diesel; Diesel Engineering and Diesel Mechanic/Technician college instructor, and college department head at Vancouver Community College He is a director and Past President of the VCC Faculty Association In 1987, he formed his own company, HiTech Consulting Ltd., specializing in technical training program design/implementation aimed specifically at heavy-duty, on- and off-highway equipment He has designed and implemented training programs for a number of large truck fleets as well as for mining companies He has set up fleet maintenance programs and been a speaker at a number of adult education seminars He is a prolific author of ten automotive, diesel, and heavy-duty truck books for Simon & Schuster's, Prentice Hall college division, where he has also been a book series editor He has also written numerous technical articles for publication in local and national technical magazines He is a member of SAE (Society of Automotive Engineers) International, in which he has held positions as the past chair of the local British Columbia Section In 1989-1990, under his leadership, the section was presented an SAE Award of Merit for outstanding technical meetings At the International level of SAE, he served three years on the Sections Board, and was both Vice-Chair and Chair He cochaired the 1992 Section Officers Leadership Seminar held in Warrendale, PA., for worldwide section officers, and returned in 1993 as Chair Other activities within SAE at the Sections Board level include: Chair of the Executive Committee; Past-Chair of the Administrative Committee; member of the Section Evaluation and Awards Committee and the Section Activities; Chair of the Brazil Ad Hoc Committee and subsequently Chair of the International Sections and Affiliates Committee; member of the Regional Coordinators Committee where he was responsible for the provinces of British Columbia, Alberta and Manitoba, as well as an acting RC for the NW / Spokane-Intermountain and Oregon Sections; and member of the Total Quality Management Committee He was appointed to the Board of Director's for SAE International for a three-year term covering 1994 to 1996, where he has been involved as a member of the DPCC (Development Project Coordinating Committee), the Appeals Board, and is currently a member of the Total Life Cycle Committee which is studying and implementing a Service Technician Society as part of SAE His military background includes service with the Army Emergency Reserve of the British Army in both the Paratroop Regiment and the R.E.M.E (Royal Electrical Mechanical Engineers) He is a former Scottish amateur boxing champion, semi-professional soccer player, a very active long-distance cyclist and skier, and enjoys restoring older cars V Preface This text has been written by this author for Prentice Hall after detailed consultation with several hundred diesel industry personnel regarding their needs for a text that reflects the latest up-to-date information dealing with electronically controlled high-speed, heavyduty diesel engines The book is not meant to supplant the excellent service literature readily available from the major engine, truck, and equipment OEM's (Original Equipment Manufacturers), but is designed to supplement their outstanding training aids A review of the chapter index will quickly highlight for you the major topics covered In conjunction with OEM service training courses and diversified technical literature, both college and vo-tech students, apprentices, and certified diesel engine, heavy-duty equipment, and commercial transport technicians have here a reference which includes the latest up-to-date technology related to current electronically controlled diesel engines Although there is some basic information related to mechanically controlled diesel engines, the industry-wide adoption of electronic fuel injection systems has forced diesel technicians to become familiar and comfortable with the basic operation, diagnosis, and troubleshooting of these technologically advanced engines and systems It has been ten years since the first electronically controlled diesel engine was released to the marketplace by Detroit Diesel Corporation in 1985.Today, all of the major engine OEM's manufacture and market highspeed, heavy-duty diesel engines equipped with electronic controls Among the major engine OEM's, we can list Caterpillar, Cummins, Detroit Diesel, Mack, Volvo and Isuzu as major users of electronic controls A thorough understanding of the design changes that have taken place in high-speed, heavy-duty diesel engines, and how each of the engine systems function and operate, is described in detail within this book Many U.S states and Canadian provinces are now moving towards mandatory diesel technician certification A recent study by the GAO (general accounting office) in the United States of over one-hundred highly skilled professions placed the needed skill levels of both automotive and diesel technicians on the same level as x-ray technicians and computer programmers One of the areas most in need of skill development for automotive and diesel technicians is a solid understanding of electronics In Chapter of this book, you will find information describing how all of the various electronic diesel fuel injection systems operate After studying this chapter, you will have a familiarization and solid background of just how similar most of these current fuel systems are No book of this type can truly reflect the wishes and needs of the diesel industry without the assistance and feedback of many of my colleagues Within the acknowledgement list in this preface, you will find major OEM's who were kind enough to support me with information on their latest product offerings I trust that the finished product is reflective of their commitment to excellence in all of their technological advancements I wish you well in your pursuit of new knowledge, since your study of this book, along with handson practical experience, will enhance your ability to understand, service, and diagnose the latest electronically controlled diesel engines and fuel systems These skills will make you a very valuable addition to many employers, and will provide you with a rewarding, challenging, and fulfilling career for many years to come vii ACKNOWLEDGMENTS Allied Signal Truck Brake Systems Company, Elyria, OH 44036 U.s.A., Becky MacDonald, Manager, Communications Caterpillar Inc., 100 NE Adams Street, Peoria, IL 61629 U.S.A., Mr Randy R Richards, Director, New Product Technology; Linda L Schearer, Corporate Legal Asst., Patent Department Chevron Research and Technology Company, a division of Chevron U.S.A Inc., San Francisco, CA 94120, U.S.A Mr William P Blum, Marketing Communications Manager; Mr Steve Quan, Senior HRD Representative, Corporate Human Resources Corning Incorporated, Corporate Communications Div., Coming, N.Y 14831 Cummins Engine Company, Inc., Columbus, IN 47202, U.S.A Mr John R Keele, Director of Marketing, and Mr Gary M Gron, Corporate Patent Counsel DAF Trucks, DAF B.V., Eindhoven, Netherlands Davco Manufacturing Corporation, P.O Box 487, Saline, MI 48176, U.S.A., Mr Paul B Smith, VP Corporate Support & Engineering Detroit Diesel Corporation, 13400 Outer Drive West, Detroit; MI 48239, U.S.A Mr: Charles Yount, Manager, Advertising and Publishing Diesel & Gas Turbine Publications, 13555 Bishop's Court, Brookfield, WI 53005, U.S.A., Mr Robert A Wilsoh, Publisher 10 Donaldson Company, Inc., P.O Box 1299, Minneapolis, MN 55440 U.S.A., Mr Jock Donaldson, Director of Marketing 11 Engelhard Corporation, 101 Wood Avenue, Iselin, N.J 08830, U.S.A Mr Richard A Gay, Marketing Manager, Automotive Emissions Systems 12 Farr Company, 2221 Park Place, EI Segundo, CA 90245, U.S.A Mr John W Martin, Marketing Services Manager 13 GMC Truck Division, General Motors Corporation, 31 Judson Street, Pontiac, MI 48058 U.S.A 14 Hastings Manufacturing Company, 325 N Hanover Street, Hastings, MI 49058, U.S.A Mr Norman W Pugh, Manager Piston Ring Engineering 15 Horton Industries, Inc., P.O Box 9455, Minneapolis, MN 55440 U.S.A., Mr Nels C Johnson, VP, Sales & Marketing viii 16 Jacobs Manufacturing Company, Chicago Pneumatic Tool Co., 22 E Dudley Town Road, Bloomfield, CT 06002 U.S.A 17 Kent Moore Division, SPX Corporation, 28635 Mound Road, Warren, MI 48092, U.S.A Andrea Kolton, Advertising Manager 18 Kold Ban International, Ltd., 900 Pingree Road, Algonquin, IL 60102, U.S.A Mr James O Burke, VP Marketing 19 Kwik-Way of Canada, 95 Norfinch Drive, Toronto, Ontario M3N lW8 Mr Julio Giron, District Manager 20 Mack Trucks, Inc., 2100 Mack Blvd Allentown, PA 18105, U.S.A Mr Bob Young, Coordinator Service Publications 21 Neway Manufacturing, Inc., P.O Box 188, Corunna, MI 48817, U.S.A 22 Parker Hannifin Corporation, Racor Division, 3400 Finch Road, Modesto, CA 95353, U.S.A Kathleen Edge, Marketing Services Manager 23 Phillips & Temro Industries, Inc., Eden Prairie, MN 55344, U.S.A., and Winnipeg Manitoba, Canada Mr Lance Toepper, General Manager, Ihdustrial Division; Marion E Lambrecht, Marketing Communications Manager 24 Robert Bosch Inc., Mississauga, Ontario, LSN lRl, Canada Mr Hans Ruschka and Mr Krishna Pan, Technical Information 25 SAE (Society of Automotive Engineers) International, Inc., 400 Commonwealth Drive, Warrendale, PA 15096 U.S.A., Mr Antenor R Willems, Publications Group Director 26 Stanadyne Automotive Products, Diesel Systems Division, 92 Deerfield Rd., Windsor, CT 06095, U.S.A 27 Sunnen Products Company, 7910 Manchester Avenue, St Louis, MO 63143 U.S.A., Mr Bob Davis, Marketing Communications Manager 28 Superflow Corporation, 3512 N Tejon, Colorado Springs, CO 80907, U.S.A Mr G Neal Williams, President 29 The Penray Companies Inc., 1801 Estes Ave., Elk Grove, IL 60007, U.S.A., Mr Ed Eaton, Director Technical Services 30 Williams Controls Inc., 14100 SW 72nd Avenue, Portland, OR 97224 Kathy Brown, Sales & Marketing Manager 31 ZEXEL USA, Technology and Information Division, 37735 Enterprise Ct., Farmington Hills, MI 48331 U.s.A Mr Shin Takeshita Contents Introduction Future Engine Developments Repair Market • 1 Diesel Engine Operating Fundamentals General Engine Designs and Classifications Four-Stroke Cycle Operation Two-StrokeCycle Operation 14 Valve Timing 16 Piston Positions 17 Comparison of Two- and Four-Stroke-Cycle Designs 17 Engine Firing Orders 20 Diesel Engineering Fundamentals 21 Energy 22 Work 23 Power 23 Metric Horsepower 23 Horsepower Formulas 23 Horsepower Ratings 28 Engine Torque 29 Torqe Rise 31 BMEPFormula 32 BSFCFormula 33 Thermal Efficiency 35 Heat Losses 36 Engine Speed Droop 36 Engine rpm Formula 36 Joule's Equivalent 36 Air Standard Cycles 37 Pressure-Volume Curves 37 5 Gasoline Versus Diesel Engines 40 Burn Rate 41 Volumetric Efficiency 42 Engine Displacement and Compression Ratio 42 Metric Measures 45 VelocityRate 45 Prefixes 47 Heating Value Equivalents 47 ISO Standards 47 • Combustion Systems 51 Combustion Chamber Designs 52 Air Turbulence 53 Combustion Dynamics 53 Chemical Theory of Combustion 56 Makeup of Air 57 Combustion in the Cylinder 57 Pr9cesses of Combustion: Diesel Engines 58 Fuel Injection Timing 59 Retarded Versus Advanced Timing 62 Fuel Quantity Requirements 62 Thermal Efficiency 63 Exhaust Emissions Limits 63 • Diesel and Alternative Fuels Crude Oil and Its Refining Process Diesel Fuel Oil Grades 69 67 67 ix Grade No 1D 69 Grade No 2D 70 Fuel Grade and Engine Performance 70 SpecificGravity of a Fuel 70 Heat Value of a Fuel 70 Fuel Recommendations 72 Major Characteristics of Diesel Fuels 72 Volatility(ASTM)Designation 72 Cetane Number 74 Viscosity 75 Carbon Residue 76 Sulfur Content 76 Flash Point 77 Cloud Point 77 Pour Point 78 Ash Content 78 Corrosion 78 Diesel Fuel Operating Problems 78 Fuel Temperatures 78 Fuel Consumption 78 Injector Cleaners 79 Fuel Additives 79 Diesel Fuel Quality Tester 81 Introduction to Alternative Fuels 81 Diesel Fuel Advantages 81 Gasoline 82 Methanol 82 Methanol in Diesel Engines 83 Methanol-Fueled Engines 84 Dimethyl Ether 85 Ethanol 85 Compressed Natural Gas 85 Natural Gas Engine Operation 86 Safety Record of CNG Vehicles 89 Liquified Natural Gas 90 Propane 91 Hydrogen 93 • Fuel Filters, Fuel/Water Separators, and Fuel Heaters Fuel Filtration 98 Water-An Engine's Worst Enemy Fuel Filters 99 Filter Change Intervals 100 Fuel Filter/Water Separators 101 Fuel Heaters 103 Hot Line Fuel Heater 103 Cold Weather Operation 104 X 98 98 • Types of Fuel Systems 108 Mechanical Fuel Systems 108 High- and Low-Pressure Fuel Systems 108 Pump-Line-Nozzle System Operation 110 PLN Plunger Operation 111 Metering Principle 111 InjectionPump Delivery Valves 113 Inline Pump-to-Engine Timing 113 Static Spill Trming 115 ElectronicPLN System 116 Unit Pump System 119 Distributor Pump System 119 Fuel Flow 120 Charging and Discharging Cycle 120 Fuel Return Circuit 122 ElectronicDistributor Pump 122 Mechanical Unit Injectors 123 Phases of Injector Operation 125 Injector Sizes 126 Care and Testing of Unit Injectors 126 MechanicalInjector Tests 127 Overview of Electronic Unit Injectors 127 System Elements 128 Sensors 131 BasicSensor Arrangement 131 Types of Sensors 132 Oil Pressure Sensor Operation 134 ElectronicFoot Pedal Assembly 135 Operation of Electronic Unit Injectors 136 System Operation 137 Series50 and 60 Fuel System 138 Fuel Injector Operation 140 ElectronicControl Modules 141 ECMOperational Description 143 ECMControl Functions 143 ECMSafety Precautions 144 ECMDiagnostic Access 145 ECMSAETrouble Codes 146 Detroit Diesel Electronic Systems 149 DDECill: Evolution and Advantages 149 Engine Sensors and Location 150 Engine Protection System 154 Engine Diagnostics 154 ECM and Special Tools 155 Diagnostic Codes 157 Using the MPSI DDR 157 Caterpillar Electronic Fuel Systems 162 EUI Operations 162 EUI Electronics 162 Fuel System Layout 168 System Troubleshooting 171 • 11 • Crankshafts, Bearings, Seals, and Dampers 266 Camshafts, Balance Shafts, and Valve Operating Mechanism Purpose of Crankshafts 266 Design and Materials 267 Crankshaft Removal 269 Procedure 270 Initial Cleaning 271 Journal Measurement 271 Thrust Surface Inspection 272 Polishing the Journals 272 Grinding the Crankshaft 274 Crack Detection Methods 276 Magnetic Particle Method 277 FluorescentMagnetic Particle Method 277 Fluorescent Penetrant Method 278 Failure Analysis of the Crankshaft 278 Types of Breaks 279 Categories of Failure 279 Multiple-Piece Crankshaft 281 Crankshaft Web Deflection 282 Crankshaft Installation 284 Main and Con-Rod Bearings 287 Designs 287 Bearing Loads 289 In-Frame Bearing Removal 289 Bearing Inspection 291 Bearing Failure Analysis 292 Avoidance of Main Bearing Damage 296 Crankshaft Seals 297 Rear SealReplacementand Installation 297 Front Seal Replacement and Installation 298 Crankshaft Vibration Dampers 300 Types of Dampers 300 Inspecting Rubber Vibration Dampers 302 Inspecting Viscous Dampers 303 Crankshaft Pulleys 304 Glossary of Terms 304 • 12 Purposes 309 Examples 310 Gear Backlash 312 Gear Timing 315 Gear Lubrication 317 Gear Removal 317 Gear Bearing Preload Check xii 309 318 320 Functions of the Camshaft 320 Cam Lobe Shape 321 Camshaft Types 321 Two-StrokeEngine Camshafts 322 Camshaft Timing 323 Camshaft Removal 329 Removal of Overhead Model 330 In-BlockCamshaft Check 333 Removal of In-BlockModel 333 Camshaft Inspection 334 In-BlockCamshaft Bushing Replacement 335 Removal 335 Cam Bore Inspection 337 Bushing Installation 337 Camshaft End Float 337 Balance Shafts 338 Valve and Injector Operating Mechanism 338 Valve Bridge (Crossed, Yoke) 339 Valve and Injector Adjustment 340 ValveAdjustment 340 General Procedure 340 Mack Engines 343 Cummins Engines 343 Detroit Diesel Four-Stroke-Cycle Engines 345 Detroit Diesel Two-Stroke-Cycle Engines 346 Caterpillar Valve and Injector Set 346 Rocker Arm Ratio 347 Pushrod Inspection 348 Rocker Arm Inspection 348 Cam Follower Inspection 349 Engine Compression Brakes 350 Brake Controls Schematic 350 Brake Operation 351 Jake Brake Adjustment 353 Jake Brake Options 355 • Gear Trains 13 14 Cylinder Head and Valves Purpose and Functions 358 Cylinder Head Materials 360 Design and Construction 360 Intake and Exhaust Valves 363 Valve Construction 364 Valve Rotators 365 Cylinder Head Removal 365 358 638 Chapter 22 solves the problem, replace the breather assembly If the breather is not restricted, check the operating condition of the atmospheric pressure sensor Using either a DDR or ECAp, check for any coolant temperature sensor diagnostic codes Monitor the coolant temperature sensor status, and if a problem is detected, perform a coolant temperature sensor circuit test Check for security of the individual unit injector plug-in harness connections, and make sure they are free of corrosion Inspect the ECM injector harness end connections Perform a cylinder cut-out test using the DDR or ECAP to isolate a misfiring cylinder Use either a DDR or an ECAP and check to make sure that the EEPROM or Personality Module (Cat) is programmed correctly for the engine hardware Use either a DDR or ECAP and check for a positive V sensor supply from the ECM If this check is OK, perform a sensor supply circuit test Black Smoke Check for high air inlet restriction Check for restricted fuel supply Check for poor fuel quality Check for incorrect intake and exhaust valve adjustment Check for defective unit injector Perform a cylinder cut-out test using the DDR (see Figure 5-42) Inspect the ECM connector for full connection and corrosion Check boost pressure or atmospheric pressure sensor signal Check the ECM with the DDR to see if a logged trouble code has been stored in memory You can also run the engine through a full-range speed test, and by using the DDR, program it to perform a boost pressure test; then compare the readings with test specs Connect a DDR or ECAP (Cat) and check to make sure the correct Personality Module is installed compared to the engine hardware CHECKING THE FUEL SYSTEM If an engine is misfiring, running rough, and lacking power, refer to the appropriate troubleshooting charts in this chapter They will guide you to the possible problem areas Note whether the condition occurs only at an idle rpm, high idle (maximum noload speed), or only under acceleration or at loaded conditions, since the troubleshooting charts will guide you through each general condition A quick way to determine if the fuel system is the problem is to note whether there is an unusual smoke color at the exhaust stack and to compare this with the exhaust smoke analysis chart (see Figure 22-4) Generally speaking, if there is no unusual exhaust smoke color, but the engine lacks power, then the engine is not starving for airflow, does not have high EBP, and is mechanically sound Suspect simple things such as plugged fuel filters or a restriction to fuel flow somewhere, since the engine can still run with a lack of fuel but will fail to accelerate properly, can run rough at idle, and will most likely have trouble reaching the maximum no-load rpm If it does reach the no-load rpm, but dies when a load is applied to it, fuel starvation is more than likely the cause Nevertheless consider all possible areas listed in the troubleshooting charts, start with the simplest possihilities first and move to the more complex The first rule of effective troubleshooting is to walk before you run Fuel Temperature On high-speed diesel engines, fuel temperature can adversely affect the horsepower output of the engine The optimum fuel temperature should be kept between 90° and 95°F (32° to 35°C) With each 100Ftemperature rise beyond these figures, there is approximately a 1% loss in horsepower due to expansion in the fuel on a conventional engine On turbocharged-aftercooled engines, each 100F fuel temperature rise beyond 95° to 100°F (32° to 38°C) results in approximately a 1~% horsepower loss Therefore, if you were running at a fuel temperature of 135° to 140°F (57° to 60°C), theoretically your engine would be producing approximately 4% less horsepower on a conventional engine and closer to 6% less on a turbocharged and aftercooled engine On a 350 hp engine, this would amount to about 14 hp (lOA kW) on a conventional engine and closer to 21 hp on the turbocharged and aftercooled engine Maximum temperature should NEVER be allowed to exceed 150°F (65°C), A reduction in engine horsepower can also result due to an increase in air temperature (ambient), since this causes the air to expand and therefore become less dense On a turbocharged engine, this is offset by the increase in airflow and pressure increase and the use of an aftercooler or intercooler EngineTroubleshooting On most high-speed engines, a power decrease can be expected of between 0.15 and 0.5 hp (0.11 to 0.373 kW) per cylinder, depending on the delivery capability of the fuel injector or pump for each lOOF (5°C) air temperature rise above 90°F (32°C).Therefore, when investigating complaints of low horsepower, always check to ensure that these two temperatures are within specifications If you don't, you could spend a lot of time trying to find the reason for the complaint, which is not directly related to the normal mechanical operation of the engine fuel or air inlet system If the engine fails to reach its maximum governed speed and generally seems to be starving for fuel, install a fuel pressure gauge into the secondary filter, run the engine, and check the fuel pressure with the engine manufacturer's specifications On Detroit Diesel engines, perform a fuel spill-back check Some engines have a small filter screen located just under the cover of the fuel transfer pump; check that this is not plugged If a fuel strainer or fuel water separator is used, check it for plugging and excessive amounts of water Check that all fuel lines are free of sharp bends and kinks Check the tightness of all fittings and connections from the suction side of the transfer pump back to the fuel tank Install a clear test line connection into the suction line to check for air bubbles You may have to undertake a restriction check to the fuel flow as discussed in Chapter Check the fuel transfer pump drive fqr security and proper engagement Ensure that there are no external fuel leaks, especially at the pump or injectors Also, if more than one fuel tank is employed, check to see that the balance-line valve is open between them; if a three-way valve is employed, check that it is in the correct position In certain instances you may also find that there is a restriction to fuel flow from inside the fuel tank caused by sediment or some foreign object that has dropped into the tank either during filling or maintenance checks One complaint that you may occasionally come across is that the engine runs well in the early part of a shift, but stalls and lacks power as the day wears on This could be caused by debris, such as a piece of wood or bark, especially around logging equipment A restriction to fuel flow is created as the level in the fuel tank drops and the debris is drawn over the suction line If the engine has been overhauled recently or the injection pump or injectors serviced, double-check the injection pump timing, injector release pressure, or injector timing If the engine has a considerable amount of hours or miles on it, it very well may be in need of a tune-up; however, this alone may not be the cause of the problem Too many people immediately assume that if an 639 engine is lacking power the answer is to tune it up Although many large companies have developed a sequence of checks to be carried out at certain intervals of time, a tune-up should be done only if other checks show that everything else is according to specifications When conducting a tune-up, not back off all adjustments and start from scratch Check each adjustment first and if necessary, readjust One of the first checks that should be made is to disconnect the throttle linkage and manually hold the speed control lever on the governor to the full-fuel position and accurately record the maximum governed engine rpm Reconnect the throttle linkage, place it in the full-fuel position, and compare the readings If they are not the same, adjust the linkage to correctly obtain the maximum engine rpm Similarly, the maximum governor no-load speed setting may require adjustment Ensure that there is no binding anywhere in the fuel control linkage Fuel Flow When an engine is suspected of using too much fuel, a close check of daily fuel usage versus miles (km) covered can be made In addition, fuel flow measurement systems are available from some major truck manufacturers On board computer monitoring devices are now being widely used by many truck fleets to keep an accurate check of vehicle fuel mileage A bad speedometer does not give the correct speed or the correct indication of fuel consumption An indication of low speed can cause the operator to think there is a power problem PRIMARY ENGINE CHECKS Engine Timing Improper engine timing, improper valve adjustment clearances, or an out of adjustment sequence can lead to physical, or mechanical damage, such as valves hitting pistons If the injection pump timing or injector timing is off, problems of smoking exhaust, low power, highfuel consumption, and internal engine damage can result Always ensure that the engine is timed according to the manufacturer's specifications and that injection pump and injectors are timed for the particular application for which the engine is being employed An engine timing indicator that operates off fuel pressure through a transducer pickup can be used on engines that employ a high-pressure fuel system Pyrometers Exhaust temperature gauges, more commonly called pyrometers, are extremely helpful when checking an engine for a lack-of-power complaint Most heavy-duty 640 Chapter 22 highway trucks with diesel engines are equipped with dash-mounted pyrometers, which can readily assist you in determining if both engine banks are running at the same temperature on vee-type engines On inline engines, the pyrometer can establish whether the engine is operating within the range specified by the engine manufacturer The most common form of pyrometer uses a pickup/ or thermocouple, consisting of two wires of different metals welded together at their ends-a hot junction The metals used in these wires are selected for their response to temperature and ability to withstand high heat As the hot junction is exposed to a heat source, a small electric current is generated at the junction; it flows through the wires to the measuring instrument, which is a millivoltmeter The amount of current flow is proportional to the heat created at the hot junction Many companies offer pyrometers that can be readily used by one person during troubleshooting These are of the handheld type; they have a heat probe that registers temperature upon contact with the surface to be checked The newer pyrometers that offer a digital readout are very helpful Just point the infrared thermometer, pull the pistol trigger, and an instant reading is recorded on the face Engine exhaust temperatures vary in engine types based on fuel setting, horsepower, speed, and load conditions Typical full-load exhaust temperatures can range as follows: • Two-stroke-cycle diesel: 585° to 740 P (307° to 393°C) • Pour-stroke cycle diesel: 647° to 1030 P (342° to 554°C) Maximum governed rpm adjustment improperly set Use an accurate digital tachometer to determine engine speeds Internal governor problem Oil pullover from an oil bath air cleaner or other external fuel source such as blower or turbocharger seals Running the engine with the governor linkage disconnected Operator problem This particular problem is not unusual on mobile equipment and highway truck operation If an operator allows the engine rpm to climb beyond the maximum safe road speed for a particular gear, in effect, the vehicle's road wheels become the driving member As there is a direct mechanical link from the road wheels to the differential and the driveline, this increased road wheel speed works through the transmission, causing the engine to be the driven member instead of the driving member During this time, it matters not that the operator has his or her foot on the throttle, since the governor will react to pull the engine to a decreased fuel situation Even if the operator has the throttle in the idle speed position, the road wheels as the driving member can spin the engine to a point that the valves strike the piston crown, leading to mechanical failure of the engine Therefore, caution drivers and operators about excessive road speed when going down long inclines and steep hills Peak torque exhaust temperatures, which occur at a lower engine speed, will consistently show higher temperatures of 200 P (93°C) plus over those encountered under full-load engine speed conditions at the rated governed engine rpm Two-stroke-cyle engines run cooler than fourstroke cycle engines due to the shorter power stroke in crankshaft degrees, plus the fact that almost twice the airflow is pumped through the two-cycle engine Approximately 30% of the cooling on a two-strokecycle diesel engine is achieved by airflow alone Engine Overs peed The maximum speed of diesel engines is controlled either by a mechanical or electronic governor assembly (see Chapter 6) Causes of possible engine overspeed can usually be traced to the following conditions: Detonation Do not confuse the normal combustion sound within the engine for this complaint Some engines run louder than others, and many of them have a peculiar sound common to that particular engine or application Pressure pulsations within the engine cylinder create the condition often referred to as diesel knock; it is an inherent characteristic of all diesel engines Experience will tune your ear to pick up sounds other than the normal combustion pressure sounds Often it is helpful, even to an experienced mechanic, to isolate any irregular noises with the use of an engine stethoscope, which amplifies sounds remarkably well A piece of welding rod or even a lead pencil placed on the engine with the other end at your ear can magnify sounds reasonably well If detonation occurs, check for the following conditions: EngineTroubleshooting • • • Lube oil picked up by the air intake stream to the engine; this also causes engine overs peed Low coolant temperature caused by excessive periods of idling and light-load operation or coldweather operation without proper attention to maintaining coolant operating temperatures Faulty injectors: leaking fuel, fuel spray-in pressure low High-Horsepower Complaint Both mechanically governed and electronically controlled diesel engines are adjusted for a specific horsepower (kW) at a specific engine speed setting If the mechanical governor settings are tampered with, or the ECM-EEPROM settings are reprogrammed, it is possible to increase the maximum rated power output of the engine for a given application This can cause an increase in fuel consumption, higher noise levels, and shorter engine, clutch, transmission, and driveline life If a complaint of this nature is made, carefully check the engine power setting by running the engine on a dyno, or if in a vehicle, on a chassis dyno, to confirm the settings The ECM options and power settings on electronic engines can be checked by accessing the ECM programming with the aid of a DDR or an ECAP (see Figures 5-40 and 5-64) Crankcase Oil Dilution This complaint is sometimes referred to by mechanics as "the engine is making oil," meaning that 'the engine oil level continually rises above the full mark on the dipstick This is generally due to fuel oil leakage from under a rocker cover fuel line connection or from leaking injector O-ring seals Crankcase dilution of DOC two-stroke 71 and 92 series engines can be caused by overtightening of the fuel pipe retaining nuts on the injector body fuel stud Additional fuel leakage on these engines can occur from the fuel stud that is screwed into the cylinder head On DOC four-stroke engines, fuel leakage can occur at the injector upper seal rings (see Figure 5-36a) On Cummins 14L (855cu in.) and LlO and MIl engines, fuel leakage can occur from O-rings (see Figure 5-70) Caterpillar electronic unit injectors have several O-rings around the body (see Figure 5-32) On the Caterpillar 3116 engine mechanical injector assembly, there is an O-ring seal on the body On Mack engines, check the injector nozzle holder O-ring seals for signs of leakage To check for fuel leaks under the rocker cover, start and run the engine with the cover off, if possible If it is not possible to run the engine, simply seal off the fuel return line from the injection pump or engine return line and apply low pressure (not to 64 exceed normal fuel system pressure) to the system with a small priming pump Carefully check all fuel lines and the injectors for signs of fuel leakage and correct as necessary In some cases it may be necessary to remove the injector or nozzle holder assembly and mount it in a pop-tester The fuel pressure can then be raised to just below the nozzle/injector release pressure; then the pop-tester valve can be closed and an inspection made for signs of fuel leakage at the suspected areas Piston Scuffing, Scoring, and Possible Seizure These problems are often caused by injectors either dribbling raw fuel into the combustion chamber, due to a faulty check valve, or by a combination of water and dirt entering the injector On multihole fuel injectors, water can blow the tip off the end of the injector With dirt passing through the small spray tip holes, they can become enlarged, leading to a flattening out of the fuel spray-in angle This can create what is commonly called wall wash, since the fuel tends to penetrate the outer periphery of the piston crown, causing burning of the outer circumference of the piston and leading to increased piston temperatures and seizure or breakup of the fire ring If the fuel sprays onto the cylinder wall, this creates wall wash and lube oil dilution, leading to eventual scuffing and scoring of the cylinder and piston Engine Vibration Misfiring cylinders as a result of low compression or faulty injectors, improper timing of individual pumping units or injectors, valves set too tight, improperly balanced cylinder banks or individual injector racks, water in the fuel, or plugged fuel filters are some of the typical causes of engine vibration However, vibration may be caused by accessory items on the engine; if so, conduct a more thorough analysis with a vibration meter Compression Checks A compression check may be necessary to determine the condition of the valves and rings On many engines this check is done with the use of a dummy injector and with the engine running (see Figure 20-22) Each make of engine will have some variation in the sequence of events required for the compression check Check the engine manufacturer's service manual for the routine and specifications A crankcase pressure check conducted using a water manometer can alert you to worn rings, as can an exhaust smoke analysis, hard starting, and low power 642 Chapter 22 Dynamometers The quickest and most effective method of determining if an engine is producing its rated horsepower i~ through the use of a dynamometer A variety of loadtesting machines are available for any purpose and application Basically, they are as follows; • • • A truck or bus chassis dynamometer (see Figure 21-7) The rear driving wheels of the vehicle are forced to drive against either a single or double set of rollers connected to the dynamometer This allows road wheel horsepower to be read directly from the dyno instrument cluster or a hard copy of test results to be printed out from a computerized interface system A stationary dynamometer that can have an engine coupled to either end of it for convenience Only one engine can be tested at a time A portable, compact, relatively lightweight dynamometer that can be bolted to the engine flywheel housing and driven from the engine flywheel This type can also be readily adapted to truck applications simply by disconnecting the driveline and coupling up the dynamometer unit reflects water or mercury displacement within the Ushaped tube in either inches or millimeters Most engine manufacturers list relative specifications in their service manuals for the particular test that you wish to conduct A typical pressure conversion chart is given in the last section of chapter 20 for converting from inches or millimeters to either pounds per square inch (kiloPascals) or back and forth between water and mercury Diesel Fuel Quality Tester Often the cause of lack of power can be attributed directly to the quality of the fuel being used in the engine Many hours can be spent in analyzing and troubleshooting performance complaints, only to find that there is nothing out of adjustment and that the engine is mechanically sound Remember, the wrong grade of fuel can affect the horsepower developed by the engine To determine if diesel fuel quality should be considered as a possible problem area when diagnosing a lack-of-power complaint in an engine, use a simple dieselfuel quality tester-basically a hydrometer (see Figure 3-5) TROUBLESHOOTING Chassis dynamometers can be a great help in testing a vehicle for engine performance if they are in good condition and used correctly When the dynamometer is not in good condition, or a bap' operating procedure is used, the result will be incorrect readings To achieve good comparison of horsepower readings from different vehicles, use the same dynamometer with the same operator Manometers One of the most effective troubleshooting tools that you can use is a set of manometers, one a water type and the other a mercury type These can be of a solidtube fashion mounted on a stand or cabinet fixture, which is usually more common in a shop setup Many mechanics prefer to use a slack tube manometer, which is a clear, heavy-plastic tube It is less susceptible to breakage and can be easily packed in a toolbox or service truck Both types perform the same function Both are known as U-tube manometers because of their shape, and they are available in sizes from 12 to 48 in (30.48 to 122 cm), with longer units available if required Manometers measure either a pressure or vacuum reading on the engine This is done through a sliding scale connected to the manometer, as shown in Figure 20-53, which can be adjusted before use to a zero position The scale is calibrated in either English or metric units or a combination of both The scale CHARTS The troubleshooting charts shown in Figures 22-8 through 22-15 deal with a variety of problems related to various diesel engines that not necessarily use the same type of fuel injection system Specific types of fuel injection systems will exhibit particular problems related to their design that may not necessarily be reflected in the same manner in another Some commonality does exist, however, between engines and fuel systems regardless of whether the engine is a twostroke or four-stroke-cycle model When using these troubleshooting charts, keep in mind that a suggested cause may not apply directly to the type of fuel injection system or engine you are dealing with If the engine is equipped with an electronically controlled fuel injection system, the special diagnostic equipment that can be plugged into these systems will quickly direct you to a stored trouble code in computer memory, so you can go to the system or area in which the problem lies Keep in mind, however, that although these engines may use electronic controls, the cause of a problem may be a simple mechanical condition that would also occur in a nonelectronically equipped engine Accept the trouble code(s) output by the computer, but also use the facuIties that were discussed earlier (see Figure 22-2), and you will solve the problem or problems Good luck in your endeavors, and keep a high standard of excellence in all your efforts Engine Troubleshooting Hard Starting Figure 22-8 is the troubleshooting chart for hard starting Possible Causes and Corrections Engine cannot be rotated Bar the engine over at least two complete revolutions 1£the engine cannot be rotated, internal damage is indicated and the engine must be disassembled to ascertain the extent of damage and the cause a Transmission or power takeoff (if so equipped) problem prevents crankshaft from turning 1£the crankshaft cannot be turned by hand, disconnect the transmission and power takeoff 1£crankshaft now turns, find the cause of the problem in the transmission or power takeoff and make necessary corrections b Inside problem prevents engine crankshaft from turning 1£the crankshaft cannot be turned after disconnecting the transmission and power takeoff, remove the fuel nozzles and check for fluid in the cylinders while turning the crankshaft 1£ fluid in the cylinders is not the problem, the engine must be disassembled to check for other inside problems Some of these inside problems are bearing seizure, piston seizure, and valves making contact with pistons Oil too thick for free crankshaft rotation Use the correct SAE grade oils for the temperatures in which the engine is operated (refer to chapter 18) At temperatures below aoc (32°F), it may be necessary to warm the oil for free crankshaft rotation a Cold outside temperatures It may be necessary to use starting aids or to heat engine oil or coolant at temperatures below -12°C (OF) Battery voltage is low or nonexistent Check battery voltage 1£battery voltage is less than volts for a 12 volt system, or 16 volts for a 24 volt system, put a charge to the batteries Recharge the battery if a light-load test indicates low or no voltage Replace the battery if it is damaged or will not hold a charge Terminals are damaged or corroded Clean or replace terminals that are damaged or corroded Cranking System has problems a Bad switch, bad wiring, or bad connection in switch circuit With ignition switch in the START position, check the voltage at the switch connection on the starter solenoid 1£there is no voltage, or if the volt- 643 age is low at this connection, check the wiring, connections, ignition switch, and magnetic switch (if used) b Bad cable or connection-battery to starter With the ignition switch in the START position, check voltage at the connection of the battery cable to the starter 1£there is no voltage, or if the voltage is low at this connection and there is good voltage at the battery, check for a bad cable or connection between the battery and the starter c Bad starter solenoid Remove and repair a solenoid that does not work when voltage is correct at both the battery and ignition switch connections d Bad starter motor 1£the solenoid works and the starter motor does not turn the crankshaft, the starter motor is bad Before removing the starter motor, turn the crankshaft by hand to be sure that a mechanical failure inside the engine, transmission, or power takeoff is not preventing the crankshaft from turning 1£ the crankshaft turns freely by hand, engage the starter motor again 1£ the starter motor still will not work, remove the starter motor and repair it, or install a new starter motor e Extra outside loads Damage to the power takeoff equipment (ifso equipped) and/or transmission can put extra load on the engine This prevents free rotation of the crankshaft To check, disconnect the transmission and power takeoff, and start the engine f Mechanical problem inside engine Take the engine apart and check all components for damage Exhaust smoke cannot be seen while starting a No fuel in tank(s) Check fuel level visually (do not use the fuel gauge only) Be sure that the dual tank selection valve is open to the tank with fuel in it Be sure that the valve in the fuel line between the tanks is open and/or the check valve is correctly installed Fuel separator (if equipped) may have water in the bowl a Low fuel pressure Change the primary and secondary fuel filters and check to make sure that the fuel lines are not plugged or damaged 1£the filters or lines are not the cause, repair or replacement of the fuel transfer pump is needed Engine Troubleshooting There may be air leaks, flow obstruction, faulty fuel pump, faulty fuel pump drive, or faulty installation a Air in the fuel system If there is air in the fuel system, the engine will normally be difficult to start, run rough, and release a large amount of white smoke If the engine does not start, loosen a fuel-injection-line nut at the through-the-head adapter and crank the engine until fuel comes out Tighten the fuel-line nut Start the engine If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel-line nuts one at a time at the through-the-head adapters until the fuel that comes out is free of air TIghten the fuel-line nuts If the air cannot be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank NOTE: Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank, or damage to the tank may result Check for leakage at the connections between the fuel tank and the fuel transfer pump If leaks are found, tighten the connections or replace the lines If there are no visual leaks, remove the fuel supply line from the tank and connect it to an outside fuel supply If this corrects the problem, the suction line (standpipe) inside the fuel tank has a leak b Low-quality fuel Remove a small amount of fuel from the tank and check for water in the fuel If there is water in the fuel, remove fuel from the tank until it is free of water and fill with a good-quality fuel Change the fuel filter and prime (remove the air and/ or low-quality fuel from the fuel system) the fuel system with the fuel priming pump If there is no water in the fuel, prime and start the engine by using an outside source of fuel If the engine starts correctly using different fuel, remove all fuel from the tank and fill with good-quality fuel Prime the fuel system, if necessary c No fuel from fuel injection pump Loosen a fuel-injection-line nut at the through-thehead adapter With ignition switch in the ON position and accelerator in the FUEL ON position, turn the engine with the starter to be sure there is no fuel from the fuel injection pump To find the cause for no fuel, perform the following steps-1 through 4-until the problem is corrected: 645 (l) 10 Use the priming pump to make sure the fuel lines and fuel injection pump housing are full of fuel (2) Check the shutoff solenoid With the ignition switch on, the plunger should be fully retracted to allow full-rack travel Also, remove the rack position indicator cover and check to see if the fuel rack has moved to the FUEL ON position (toward the rear of the engine) This can be an indication of possible governor problems If rack travel is restricted, replace the solenoid or repair the governor (3) If you are not using a good-quality fuel at temperatures below -l2°C (lO°F), it is possible that the fuel in the system can wax (not have correct flow characteristics) and cause a restriction in the fuel system Install a new fuel filter It may be necessary to drain the complete fuel system and replace with a No grade of fuel (4) Check for fuel supply line restriction by removing the fuel supply line for the fuel filter base Put 35 kPa (5 psi) of air pressure to the fuel tank If there is no fuel, or only a weak flow of fuel from the fuel supply line, there is a restriction in the fuel supply line and/ or the fuel tank d Check the air inlet and exhaust systems for restrictions Check for SRS and TRS signals using the diagnostic data link reader on electronically equipped engines Perform a cylinder leak-down test (as outlined in Chapter 20 (Figure 20-24) or an engine compression check (as shown in Figures 20-21 and 20-22) Abnormal Engine Operation The troubleshooting chart for abnormal engine operation is shown in Figure 22-9 Misfiring and Running Rough Possible Causes and Corrections Perform a cylinder cutout test Refer to the engine manufacturer's diagnostic troubleshooing guide or to the information in this chapter dealing with mechanical and electronic unit injectors as well as inline pump and nozzle systems EngineTroubleshooting a Air or water in fuel system If there is air in the fuel system, the engine will normally be difficult to start, run rough, and release a large amount of white smoke If the engine does not start, loosen a fuel-injection-line nut at the through-the-head adapter and crank the engine until fuel comes out Tighten the fuel-line nut Start the engine If the engine does not run smooth or releases a large amount of white smoke, loosen the fuel-line nuts one at a time at the through-the-head adaptors until the fuel that comes out is free of air Tighten the fuel-line nuts If the air cannot be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank NOTE: Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank, or damage to the tank may result Check for leaks at the connections between the fuel tank and the fuel transfer pump If leaks are found, tighte~the connections or replace the lines If there are no visual leaks, remove the fuel supply line from the tank and connect it to an outside fuel supply If this corrects the problem, the suction line (standpipe) inside the fuel tank has a leak Water in the fuel.can cause rough running and possible fuel system damage b Valve adjustment not correct Check and make necessary adjustments according to the engine service manual Also check closely for a possible bent or broken pushrod c Bad fuel nozzle(s) Find a bad nozzle by running the engine at the rpm where it runs rough Loosen the high-pressure fuel-line nut at the cylinder head enough to stop fuel supply to that cylinder (see Figure 22-7) Each cylinder must be checked this way If a cylinder is found where loosening of the nut makes no difference in the rough running, remove and test the nozzle for that cylinder d Fuel leakage from fuel-injection-line nut Tighten the nut to specs Again check for leakage Be sure to check the fuel injection lines inside the valve cover base e Bad fuel injection pump An injection pump can have good fuel flow coming from it but cause rough running because of slow timing that is caused by wear on the bot- f g h i j k 647 tom end of the plunger Fuel pumps that are severely scored from debris can cause rough running, but fuel dilution usually occurs before horsepower is affected Low installation torque on the fuel pump retaining nut can cause misfire, rough running, and low power Fuel with a high cloud point In cold-weather operation, this condition should be checked first The fuel cloud point is the temperature at which wax begins to form in the fuel If the atmospheric temperature is lower than the cloud point of the fuel, wax will form and plug the filter Change the filter and drain the tank and the complete fuel system The replacement fuel must be of a better grade with a lower cloud point Fuel injection timing not correct Check and make necessary adjustments Automatic timing advance not operating correctly Check with engine warm Use the engine manufacturer's timing indicator group If not available, make a rapid acceleration (increase in speed) from low idle to high idle Engine must have smooth acceleration A timing advance that does not operate correctly can cause delays of the engine acceleration at some rpm before high idle, or possibly cause the engine to run rough and have exhaust noise (backfire) during acceleration This condition is difficult to find if engine acceleration is slow or at a constant engine rpm Fuel return line has restriction This condition blocks or slows the fuel flow back to the fuel tank The result is higher fuel temperatures in the fuel injection pump housing Also, the removal of air from the fuel is prevented Make a visual inspection of the fuel lines and fittings for damage and make repairs or replacements as needed Valve leakage; wear or damage to pistons and/or piston rings; wear or damage to cylinder walls The cylinder head will have to be removed to make a visual inspection of these inside problems Cylinder head gasket leakage Leakage at the gasket of the cylinder head can show as an outside leak or can cause loss of coolant through the radiator overflow Remove the radiator filler cap and, with 648 Chapter 22 the engine running, check for air bubbles in coolant caused by combustion gases Do not loosen the filler cap or pressure cap on a hot engine Steam or hot coolant can cause severe burns Check the throttle position sensor signal and circuit as well as the intake manifold air temperature sensor signal Perform a fuel flow test Determine if sufficient fuel quantity is being delivered If less than the specified amount is returning, or if the fuel is aerated, check for a fuel system restriction using a mercury manometer connected to the primary fuel filter Check the fuel spill-back temperature The relative fuel temperature should be less than 60°C (l50°F) or a loss of horsepower may occur Ideal fuel temperature should be between 90° and 95°F (32° to 35°C), since for every 100F (6°C) rise in fuel temperature above this, horsepower losses can run between 1% and 1.5% Note that 150°F (60°C) is the allowable maximum Continuing to operate an engine with temperatures higher than this will result in injection component damage as well as possible ECM damage Perform a cylinder leak-down test (as outlined in Figure 20-24), or perform an engine compression test (see Figure 20-21) Check that the air inlet restriction and exhaust back pressures are within prescribed limits Repair or replace defective parts as necessary Use a water manometer to check the air inlet restriction and a mercury manometer to check the exhaust back pressure WARNING: Low-Power Complaint When a low-power complaint is received, determine after discussions with the operator whether the lack of power is consistent or if intermittent power cutouts are the main problem Using electronic diagnostic equipment, check that the ECM operating parameters are set according to the desired horsepower setting On electronically controlled engines, poor electrical connections could be the cause, so check the vehicle harness and connectors, the ECM power, and ground connections Using a DDR or ECAP system, check for active or historical codes in ECM memory For either a consistent or intermittent low-power complaint, check the valve and injector settings, engine brake, fuel temperature, turbocharger boost sensor, throttle position sensor, and vehicle speed sensor signal Perform a cylinder cutout procedure, check the fuel supply system for restrictions and correct delivery pressure, check fuel quality, perform an air-to-air aftercooler leakage test, check air inlet or exhaust restrictions If the low-power complaint is ongoing, and you have made all of the primary engine checks, use an engine or chassis dynamometer to save a lot of diagnostic time Possible Causes and Corrections High inlet air temperature Air coming into the engine must be cool for the engine to have full horsepower If the air inlet system is not of correct design or is not in good mechanical condition, hot air can come into the engine, causing a loss of horsepower Check the air inlet temperature to the engine The engine should not be operated with a winter shield (radiator cover) in front of the intercooler The nominal air inlet temperature should be 49°C (l20°F) An approximate 1.5%power loss will be noted for each 38°C (lOO°F)the inlet air temperature is above nominal If high air inlet temperature is noted, check and clean the exterior intercooler and radiator cores Check the fan, fan drive, and fan shroud to ensure maximum airflow is provided To check the inlet air temperature, install a thermistor-thermometer into the engine air inlet pipe High-altitude operation An engine loses horsepower with an increase in altitude The percentage of power loss is governed by the altitude at which the engine is operated On many current heavy-duty high-speed truck engines, there is no effect on the horsepower of the engine for the first 2280 m (7500 ft) above sea level of operation Examine the air intake piping after the turbocharger for evidence of oil from a malfunctioning turbocharger Check the engine coolant temperature gauge for accuracy If the coolant temperature does not reach a minimum temperature of 180°F(82°C) while the engine is operating, consult the abnormal engine coolant temperature chart (see Figure 22-14) Check the engine gear train timing An improperly timed gear train results in a loss of power due to the valves and injectors being actuated at the wrong time in the engine operating cycle Examine the check-engine light A steady checkengine light, with no codes, may indicate that the electronic control module is in the backup mode Refer to the engine manufacturer's diagnostic troubleshooting guide Engine Troubleshooting No Fuel or Insufficient Fuel • The troubleshooting chart for no fuel or insufficient fuel is shown in Figure 22-10 Possible Causes and Corrections The fuel tank should be filled above the fuel suction (pickup) tube in the tank Perform a fuel flow test If air is present, check all fuel lines and connections for cracks or damage Tighten all connections Check the fuel filters for cracks or damage, and be sure that they have been properly installed Repair worn or broken components as necessary With all fuel lines, filters, and connections correctly installed and tightened, and air in the fuel system still present, check and/or replace questioned injectors Faulty or incorrectly seated injectors are usually associated with a darkening of the fuel Check the restricted fitting on the fuel return line at the rear of the cylinder head for the correct size Check the primary and secondary fuel filters for plugging Replace as necessary Check the fuel lines for pinching, damage, obstruction, or incorrect routing Be sure that the fuel lines are of adequate siz.e Check for correct installation and operation of the fuel check valve or shutoff valve (if so equipped) Check for fuel temperature being less than 6°C (lO°F)above the pour point of the fuel Bypass the electronic control module cold plate 10 Check the fuel pump and relief valve Check the fuel pump drive and coupling Repair or replace worn or damaged components as necessary 11 In the event of a no-fuel! no-start situation and no check-engine light displayed, check for voltage at the electronic injector terminals while cranking the engine If no voltage is present, consult the engine manufacturer's diagnostic troubleshooting guide High Fuel Consumption A measurement of fuel consumption is used to check fuel system performance If fuel consumption of an engine is within OEM specifications, the fuel system is performing correctly and no additional time should be spent checking fuel delivery • • 649 Fuel consumption If the specified amount of fuel is being injected into the engine, the fuel delivery specification is being met Therefore, the basic fuel system (fuel pump and lines, transfer pump, filters, and primary fuel pressure) is within functional limits Additional time spent troubleshooting these components is probably not justified Fuel system timing Fuel cannot be burned efficiently if it is not injected into the cylinder at the correct time Because engines develop horsepower only when they are running, timing must be measured when they are running The static pin timing of the engine is not adequate Timing must be measured throughout the speed range (this also checks the timing advance operation) Intake manifold pressure Manifold pressure is an indication of the overall health of the engine Boost is affected by anyone or all of the following: fuel consumption, compression (valve condition, piston ring condition), turbocharger performance, intake restriction (air filters), exhaust restriction (muffler), and timing Complaints about fuel consumption are related to engine owners' expectations They may be related to the engine itself or causes other than the engine; in some cases, the fuel consumption may be normal for the application Only a good discussion with the owner / operator, as described next, will guide you to a correct repair or prevent unnecessary repairs The following questions should be asked before beginning any diagnosis or repair for an engine performance complaint There are no hard and fast answers for these questions Many factors can cause poor fuel mileage, or make users believe they are getting poor fuel mileage Customer expectations are also a factor The answers to these questions will give you a better understanding and perspective on the complaint and may identify characteristics that will help pinpoint the cause of the complaint quickly Are miles measured accurately? A most common problem in determining mpg is errors in recording the number of miles traveled a Is this vehicle hub or cab odometer accurate? The easiest way to check an odometer is to install a hub odometer known to be accurate and appropriate for the tire size on the truck Run the truck over several hundred miles and compare the reading with the reading of the original odometer Odometers may also be checked by comparing them to interstate mile posts or by EngineTroubleshooting running over a course of known length50 miles is required to get a good check Is fuel measurement accurate? There are a number of ways in which fuel measurement can be the source of mpg problems a Are fuel pumps calibrated? If fuel tickets come from company-owned fuel pumps, there can be errors because nonrevenue fuel pumps not have calibration requirements in many states b Are road fuel tickets accurate? The only way to verify fuel additions when road fuel tickets are used is a laborious ticket-byticket audit ensuring that the correct amount of fuel has been entered for the vehicles in question and that there are no indications of incorrect entries b c NOTE: Onboard vehicle computer recording devices are helpful in determining fuel consumption usage (see Figure 5-44) a Is the wheel horsepower comparable? When checking wheel horsepower, compare the horsepower ratings of competitive fleet engines; if one make of engine has more wheel horsepower or power at higher rpm, the competitive engine has an advantage b Is the maximum vehicle speed comparable? When you give the driver of the vehicle higher rpm and more power, it gives the vehicle the potential to go faster The faster the truck goes, the more fuel it will burn c Is wheel horsepower and vehicle speed higher than unit with better mpg? If an engine is set to specifications and this does not equalize the wheel horsepower and vehicle speed, the use of an alternate lowerhorsepower rating-when available for the same engine-should be considered Are the tractor specifications comparable? Often, a general discussion or questioning of a tractor's specifications will uncover a significant difference that leads to differences in mpg results a Tires The difference in fuel efficiency between radial and bias-ply tires is well known A vehicle or a fleet of vehicles that have bias-ply tires will have worse fuel consumption than those with radial tires Also, tire size changes have the same effect as changes in rear end ratio d e f 651 Rear end ratio One objective in choosing a rear end (axle) ratio for optimum fuel consumption is to limit the engine rpm at the user's desired road speed Normally, a higher ratio (lower number) will yield better fuel consumption at a given speed In some situations, however, the higher ratio can give additional vehicle speed, which will hurt the fuel consumption if the higher potential vehicle speed is used Transmission ratios The transmission ratio difference that has the greatest effect is an overdrive transmission versus a direct transmission with the same rear end ratio Obviously, the overdrive ratio allows the vehicle to go faster, which can hurt mpg; but overdrives can be used to reduce average engine rpm at a low vehicle speed, which helps mpg Therefore, the same situation exists as with rear end ratios What can be good in one application can be bad in another The number of gears in the transmissions can also be significant The effect of the number of gears depends on the skill and motivation of the driver Again, general rules not always apply, but less skillful drivers would probably get better mpg results with or speed transmissions than with a 13 speed transmission A very skillful driver may be able to get better mpg with a 13 speed transmission Temperature-controlled fan A malfunctioning or poorly engineered temperaturecontrolled fan can be a very significant contributor to an mpg complaint An appropriate question for all mpg complaints is, Does the temperature-controlled fan run often? If the answer to that question is "yes," normally there is something wrong with the way the temperature-controlled fan is installed or engineered, or there has been a system malfunction Normally the fan will operate about 10% of the time! Cab aerodynamics or cab style There can be significant differences in aerodynamics, and therefore, mpg between two cab designs The effects are not always predictable When cab designs of two vehicles are different, it is difficult to make comparisons or prove that engines are the source of mpg complaints Air deflector and air deflector setting Use of wind screens or air deflectors is common 652 Chapter 22 today Obviously, different brands of air deflectors perform differently Also, some deflectors may be adjusted to various settings that affect their performance g Gap between back of cab and trailer The performance of air deflectors and the fuel consumption of tractors without deflectors are greatly influenced by the distance between the back of the cab and the front of the trailer The wheelbase of the tractor, and therefore, distance between the back of the cab and the front of the trailer, significantly affect mpg The closer the trailer is to the tractor, the better the mpg will be Is the operation the same for all units? For dump trucks, mixers, garbage trucks, and so on, variations in the operation that can be very difficult to find may have significant effects on mpg a Assigned or slip-seat drivers With assigned drivers, the driver's driving habits are applied to the vehicle directly The assigned driver can be the total problem In a slip-seat operation where different drivers drive the truck every trip, the effect of the driver on fuel consumption is essentially eliminated b Routes If vehicles consistently ru~ different routes, there is an effect on mpg c Equal loads If one vehicle is consistently at a significantly higher gross weight than another vehicle, it will have poorer fuel consumption than the lighter unit d Assigned trailers, trailer aerodynamics, and trailer tires If one tractor always pulls a vertical rib trailer and another tractor always pulls a smooth-sided trailer, the tractor pulling the smooth-sided trailer has an advantage as far as fuel consumption is concerned The same is true if one trailer has radial tires and another trailer has bias-ply tires; if one trailer is properly aligned and another is not; or if one trailer is higher than another e Operational changes and weather changes Some mpg complaints can result from operational changes Moving trucks from one location to another can have a dramatic effect on fuel consumption Changes in the weather also change fuel mileage dramatically An industry rule of thumb of 10% to 15% loss in fuel mileage from summer to winter is a close approximation of actual results for fleets that run throughout the country Possible Cause and Corrections Check records used to determine fuel consumption Make sure that the records are accurate The minimum period for accurate fuel records is month or 10,000 miles Check the tires (air pressure and size), the gap between the tractor and trailer, air deflectors, trailer width, trailer type, engine cooling fan, and driver habits Determine minor operating faults To help identify a problem before a more involved troubleshooting procedure is started, follow the procedure given in the section "Primary Engine and Vehicle Checks." Fix an air/fuel ratio control that is out of adjustment or bad Check engine performance Be sure to make a record of the temperatures for inlet air, fuel (at filter base), lubricating oil, and coolant Also, check for excessive exhaust smoke At this point, the governor fuel settings should be verified Replace worn fuel nozzles Check the horsepower on a dynamometer Make a replacement of the fuel injection nozzles and check the horsepower output again If there is more than 10 hp difference, the old nozzles had eroded orifices and were causing high fuel rate Fuel in Crankcase Oil Possible Causes and Corrections Loose inner fuel-injection-line nut(s) A loose fuel-injection-line nut or a bad a-ring seal on the end of the adapter inside the cylinder head can cause fuel leakage into the crankcase Check for a bad a-ring seal and tighten nuts to specifications On DOC engines (two-stroke models), distorted or bent fuel jumper lines or damaged pipe flared-end conditions can cause severe crankcase oil dilution Fuel nozzle leaks A loose bleed screw (Cat 3406 model mechanical fuel systems) or leaking bleed screw washer will cause fuel dilution in the crankcase Check for bad bleed screw washers or damaged bleed screw washer face Make sure that the bleed screws are tightened to specifications On unit injectors, check for fuel leakage at the injector a-rings ... for Canada, service representative, and sales application engineer with Detroit Diesel; Diesel Engineering and Diesel Mechanic/Technician college instructor, and college department head at Vancouver... certified diesel engine, heavy-duty equipment, and commercial transport technicians have here a reference which includes the latest up-to-date technology related to current electronically controlled diesel. .. electronically controlled diesel engine was released to the marketplace by Detroit Diesel Corporation in 1985.Today, all of the major engine OEM's manufacture and market highspeed, heavy-duty diesel engines