Great Wall GW4D20 User manual

GW4D20/GW4D20B 型增压柴油发动机维修手册
MAINTENANCE MANUAL OF GW4D20/GW4D20B
TURBOCHARGED DIESEL ENGINES
保定长城内燃机制造有限公司 编
Edited by Great Wall Baoding Internal Combustion
Engine Manufacturing Company Limited
长城内燃机
GREAT WALL ENGINES

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
II
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Introduction
This maintenance manual describes the primary technical data, troubleshooting, maintenance,
disassembly and assembly, adjustment, repair and other related information of the GW4D20/GW4D20B
turbocharged diesel engines so as to provide reference for the related maintenance personnel and
repairman.
GW4D20/GW4D20B 型增压柴油发动机维修手册
WAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
Edited by Great Wall Baoding Internal Combustion Engine Manufacturing Company Limited
*
CAAMS-1098-138/G·438-QC-09~10-580.00

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
III
Foreword
The GW4D20/GW4D20B turbocharged diesel engine is 4-cylinder in line, 4-stroke, 16-air valve, double
overhead camshaft (DOHC), turbocharged (VGT, WGT), air intake intercooled vehicle engine, and
adopts advanced technologies such as the electric control high-pressure common-rail system, electric
control EGR system, etc; it features good power performance, high economical efficiency, high reliability,
excellent performance at both high and low speeds, quick low-temperature startup, etc., and its emission
conforms to China IV Vehicle Exhaust Emission Standard.
The GW4D20/GW4D20B diesel engine is mainly carried various kinds of LCV, SUV/MPV, compact cars,
high-grade pickups produced by Great Wall Motor Company Limited and similar models from other auto
manufacturers.
AS a kind of power machinery reaching the modern advanced level, the GW4D20/GW4D20B
turbocharged diesel engine has complicated structures, and has strict requirements for the material,
technology and cooperation between parts, and correspondingly requires high levels of application,
maintenance and repair.
Maintenance Manual of GW4D20/GW4D20B Turbocharged Diesel Engines is a comprehensive manual
for engine maintenance; it consists of the primary technical data, disassembly and assembly, adjustment,
examination and troubleshooting, etc of the GW4D20/GW4D20B turbocharged diesel engine; you
should carefully read and strictly follow the regulations in the manual and master malfunction diagnosis,
elimination and maintenance of the diesel engine so as to ensure the best working condition of the
engine after maintenance and make the engine reach the desirable power performance and economical
index.
As for the vehicle and mechanical chassis parts concerned in maintenance, repair and troubleshooting
of the diesel engine or the parts supplied by auto and machinery manufacturers, please refer to the
maintenance manual of the vehicle or machinery carrying the engine.
For your life and property security, please use and operate the engine in strict accordance with the safety
information described in this manual. The instructions to important issues should be complied strictly,
otherwise it may cause serious injury or machine, vehicle damage and even danger. The warning in this
manual refers to possible personal danger; caution refers to possible damage to the diesel engine and
attention is used for important information without danger.
Please note that the GW4D20/GW4D20B turbocharged diesel engine will be continuously improved
according to market demands and changes, and information on maintenance and repair of improved
parts will be amended or supplemented when the manual is reprinted.
Contents and technical information from this manual are effective as long as the printing is approved. But
the Great Wall Baoding Internal Combustion Engine Manufacturing Company Limited (called our
company for short thereafter) reserves the right to suspend using and change technical information and
the design at any time without previous notice, and the right to change the supply scope, equipment and
technology. Therefore, users cannot have any claim on the basis of the data, illustrations and
explanations described in this manual. Changes in the range of the product structure, equipment and
technology will not be noticed to users, and our company will not assume any relevant responsibility or
obligation.
We hope to get feedbacks concerning advices on the qualities, performances and structures,
experiences in operation, maintenance and repair of GW4D20/GW4D20B turbocharged diesel engines
from users and readers so as to help us improve our products and technologies of operation,
maintenance and repair. Please send your letter to: Sales and Services Department, Great Wall Baoding
Internal Combustion Engine Manufacturing Company Limited, Dingxing County Development Zone,
Hebei Province, China, Postal Code: 072650.

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
IV
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Since this manual covers wide information and is edited in short time, careless omission and even errors
may be detected, and we would greatly appreciate being informed of them. This manual only provides
reference for users in work, and we will not be responsible for any loss or damage caused by using this
manual.
Our company has its authorized repair stations in various regions, users can get consultation and
after-sale service from the nearest authorized repair station on issues concerning use, technical
maintenance, troubleshooting, repair or parts replacement of the diesel engine.
This maintenance manual should not be reprinted or published without the permission from our company.
Our company reserves all copyrights that described in law, and reserves the rights of modification and
explanation.
Great Wall Baoding Internal Combustion Engine Manufacturing Company Limited
Dec. 18, 2009

Table of Contents
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
V
Table of Contents
Chapter I Introduction..............................................................................................................................1
Section I How to Use This Manual.............................................................................................................1
Section II Main Contents of Civilized Production for Maintenance............................................................4
Section III Fire Control Measures for Maintenance Workshop..................................................................4
Section IV Dress Security Requirements for Maintenance Personnel ......................................................5
Section V Main Contents of Maintenance Process Regulation .................................................................5
Section VI Identification Marks...................................................................................................................5
Section VII General Repair Instructions.....................................................................................................6
Section VIII Precautions for Maintenance Operation.................................................................................8
Chapter II Technical Information of Engine...........................................................................................9
Section I Structure of Engine......................................................................................................................9
1. Cylinder head and cylinder body................................................................................................. 9
2. Crank and Connecting Rod Mechanism...................................................................................... 9
3. ValveActuating Mechanism and Intake/Exhaust System ........................................................... 9
4. Turbocharging System............................................................................................................... 10
5. Fuel Supply System................................................................................................................... 10
6. Lubrication System.....................................................................................................................11
7. Cooling System...........................................................................................................................11
8. Startup Device.............................................................................................................................11
Section II View of Engine .........................................................................................................................12
1. Front View of Engine ................................................................................................................. 12
2. Rear View of Engine.................................................................................................................. 13
3. Left View of Engine.................................................................................................................... 14
4. Right View of Engine ................................................................................................................. 15
5. Vertical View of Engine.............................................................................................................. 16
Section III Main Performance Indexes of Engine.....................................................................................17
1. Power Performance Index......................................................................................................... 17
2. Economical Efficiency Index...................................................................................................... 17
3. Reliability and Durability Index .................................................................................................. 18
4. Low Public Hazard Index........................................................................................................... 18
Section IV Engine Property Curves..........................................................................................................19
Section V Technical Data and Specifications of Engine...........................................................................21
1. Technical Parameters of Engine................................................................................................ 21

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
VI
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
2. Various Temperature and Pressure Ranges of Engine............................................................. 23
3. Specifications of Main EngineAccessories............................................................................... 24
4. Specifications of Main Parts of Fuel Supply System................................................................. 25
Section VI Maintenance Standard for Engine..........................................................................................26
1. Tightening Torque of Main Fasteners of Engine........................................................................ 26
2. Fit Clearance of Main Parts of Engine....................................................................................... 28
Section VII Running-in of Engine.............................................................................................................32
1. Preparation Before Running-in.................................................................................................. 32
2. Running-in.................................................................................................................................. 32
3. Precautions for Running-in........................................................................................................ 33
4. Technical Maintenance After Running-in................................................................................... 33
5. Precautions for Usage of New Vehicles.................................................................................... 33
Section VIII Technical Maintenance for Engine........................................................................................34
1. Technical Maintenance Cycle.................................................................................................... 34
2. Technical Maintenance Contents............................................................................................... 37
3. Technical Maintenance for Air cleaner....................................................................................... 40
4. Technical Maintenance for Oil Supply System.......................................................................... 41
5. Technical Maintenance for Fuel Lubrication System................................................................. 43
6. Technical Maintenance for Cooling System .............................................................................. 46
7. Additional Maintenance in Severe Driving Conditions .............................................................. 48
8. Technical Maintenance During Storage..................................................................................... 48
9. Precautions in Technical Maintenance...................................................................................... 48
Section IX Repair Process for Diesel Engine...........................................................................................48
1. Repair Process for Diesel Engine.............................................................................................. 48
2. Engine Handover and Repair Class Identification..................................................................... 49
3. Exterior Washing for the Engine................................................................................................ 50
Section X Technical Requirements for Engine Removal and Reinstallation ...........................................51
1. General Technical Requirements for Assembling...................................................................... 51
2. General Technical Requirements for Removal.......................................................................... 53
Section XI Special Tools and Instruments for Repair...............................................................................54
Section XII Repair Operation for Engine..................................................................................................56
1. Model Mark ................................................................................................................................ 56
2. Air Cleaner................................................................................................................................. 56
3. Lubrication System.................................................................................................................... 57
4. Fuel System............................................................................................................................... 58
5. Cooling System.......................................................................................................................... 59
6. Engine Control........................................................................................................................... 61

Table of Contents
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
VII
7. Quick start-up system................................................................................................................ 62
Section XIII Engine Parts and Tightening Torques...................................................................................63
1. Engine Bracket MountingAssembly.......................................................................................... 63
2. Cylinder Body Mounting Assembly............................................................................................ 64
3. Cylinder Body Component......................................................................................................... 65
4. Cylinder Head Mounting Assembly ——1................................................................................. 66
5. Cylinder Head Mounting Assembly ——2................................................................................. 67
6. Cylinder Head Mounting Assembly ——3................................................................................. 68
7. Piston Connecting Rod Mounting Assembly ............................................................................. 69
8. Crankshaft Flywheel and Clutch Mounting Assembly............................................................... 70
9. Air Intake and Exhaust Systems Mounting Assembly ——1..................................................... 71
10. Air Intake and Exhaust Systems Mounting Assembly ——2..................................................... 72
11. Oil Pan and Engine Oil Collector MountingAssembly .............................................................. 73
12. Engine Oil Pump Mounting Assembly ....................................................................................... 74
13. Engine Oil Cooler and Cooling Pipelines MountingAssembly.................................................. 75
14. Timing Mechanism Mounting Assembly ——1.......................................................................... 76
15. Timing Mechanism Mounting Assembly ——2.......................................................................... 77
16. Fuel Supply System Mounting Assembly ——1①.................................................................... 78
17. Fuel Supply System Mounting Assembly ——2①.................................................................... 79
18. Fuel Supply System Mounting Assembly ——3①.................................................................... 80
19. Turbocharger Mounting Assembly ——1①............................................................................... 81
20. Turbocharger Mounting Assembly ——2①............................................................................... 82
21. EGR System Mounting Assembly.............................................................................................. 83
22. Electronic Control System Sensor............................................................................................. 84
23. Generator Mounting Assembly .................................................................................................. 85
24. Throttle Mounting Assembly ...................................................................................................... 86
25. Thermostat and Water Pump Mounting Assembly.................................................................... 87
26. Engine and Compressor Mounting Assembly ........................................................................... 88
27. Vacuum Pump and Steering Pump MountingAssembly........................................................... 89
Chapter III Malfunction Diagnosis and Troubleshooting...................................................................90
Section I Troubleshooting.........................................................................................................................90
1. Failure to Start the Diesel Engine.............................................................................................. 91
2. Difficulty in Starting the Diesel Engine at a Low Temperature................................................... 91
3. Insufficient Power in the Diesel Engine..................................................................................... 92
4. Excessive Fuel Consumption of Diesel Engine......................................................................... 93
5. Abnormal Noise During the Diesel Engine Running ................................................................. 93

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Manufacturing Company Limited
6. Abnormal Noise from Diesel Engine.......................................................................................... 95
7. Abnormal Smoke from Diesel Engine........................................................................................ 95
8. Heavy Oil Consumption and Low pressure of the Diesel Engine Lubrication System ............. 96
9. Abnormal Coolant Temperature, Lack of Coolant in the Diesel Engine Cooling System ......... 98
10. Malfunction of the Diesel Engine Turbocharging System ......................................................... 99
11. Malfunction of the Diesel Engine Oil Supply System.............................................................. 100
12. Diesel Engine Wobble During Idling........................................................................................ 103
13. Diesel Engine Running at a High Idle Speed.......................................................................... 104
14. Starter not Working, Lacking Power, and Making noise.......................................................... 104
15. Working Starter but Non-working Diesel Engine..................................................................... 105
16. Diesel Engine Rotating but Unable to be Started.................................................................... 106
17. Difficulty in Starting Due to Malfunction in the Quick Start-up System.................................... 107
18. No Power Generation, Undercharge or Overhigh Charging Current of Generator................. 108
19. Insufficient Capacity, Difficulty in Starting or Overhigh Self Discharge of the Storage Battery109
Section II Malfunction Diagnosis............................................................................................................ 110
1. Start-up system malfunction diagnosis.....................................................................................110
2. Turbocharging System Malfunction Diagnosis.........................................................................114
Chapter IV Mechanical System........................................................................................................... 119
Section I Cylinder Head.......................................................................................................................... 119
Section II Camshaft................................................................................................................................137
Section III Valve, Valve Spring, Valve Oil Seal, RockerArm and Hydraulic Clearance Adjuster...........148
Section IV Crankshaft.............................................................................................................................157
Section V Piston and connecting rod assembly.....................................................................................178
Section VI Engine oil pump assembly....................................................................................................196
Section VII Cylinder body assembly ......................................................................................................201
Chapter V GW4D20 / GW4D20B Turbocharged Diesel Engine........................................................215
Section I General....................................................................................................................................215
Section II EngineAssembly....................................................................................................................216
Section III Engine Brackets....................................................................................................................225
Section IVAir Intake Manifold Pipe........................................................................................................235
Section V Exhaust Manifold Pipe...........................................................................................................240
Section VI Cylinder Cover......................................................................................................................246
Section VII Camshaft..............................................................................................................................253
Section VIII Rocker Arms and Hydraulic Clearance Adjusters ..............................................................263
Section IX Valve Oil Seal and Valve Spring ...........................................................................................273
Section X Cylinder Head Assembly and Cylinder Head Gasket............................................................286
Section XI Timing Pulley.........................................................................................................................298

Table of Contents
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
IX
Section XII Oil Filter and Oil Cooler .......................................................................................................303
Section XIII Primary shaft front bearing of the flywheel and transmission ............................................306
Section XIV Oil pump assembly.............................................................................................................310
Section XV Oil pan assembly.................................................................................................................318
Section XVI Piston and connecting rod assembly.................................................................................323
Section XVII Front oil seal of crankshaft................................................................................................337
Section XVIII Rear Oil Seal of Crankshaft .............................................................................................342
Section XIX Crankshaft..........................................................................................................................346
Section XX Cylinder BodyAssembly......................................................................................................364
Chapter VI Fuel System.......................................................................................................................384
Section I General....................................................................................................................................384
1. Components of Fuel Supply System....................................................................................... 384
2. Components of High Pressure Common Rail System............................................................ 386
Section II On-Board Maintenance..........................................................................................................400
1. Fuel Filter Assembly ................................................................................................................ 400
2. Fuel Injector Assembly............................................................................................................. 403
3. High-Pressure Fuel PumpAssembly....................................................................................... 407
Chapter VII Cooling System................................................................................................................ 411
Section I General.................................................................................................................................... 411
1. Water pump...............................................................................................................................411
2. Thermostat............................................................................................................................... 412
3. Radiator ................................................................................................................................... 412
4. Antifreeze fluid......................................................................................................................... 412
Section II On-Board Maintenance..........................................................................................................414
1. Water Pump Assembly............................................................................................................. 414
2. Thermostat............................................................................................................................... 420
3. Radiator ................................................................................................................................... 424
Chapter VIII Lubrication System.........................................................................................................428
Section I General....................................................................................................................................428
Section II On-board Repair.....................................................................................................................429
1. Oil Filter.................................................................................................................................... 429
2. Engine Oil Pump...................................................................................................................... 432
3. Oil Collector ............................................................................................................................. 439
4. Oil Pan..................................................................................................................................... 442
Chapter IX Turbocharging System.....................................................................................................446
Section I General....................................................................................................................................446
1. Turbocharging system composition......................................................................................... 446

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
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Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
2. Turbocharger structure............................................................................................................ 446
Section II On-board Maintenance ..........................................................................................................449
Section III Inspection and Repair...........................................................................................................454
1. Checking the working condition of the exhaust outlet............................................................. 454
2. Checking the working condition of the turbocharger............................................................... 455
3. Checking the axial clearance of the impeller shaft.................................................................. 455
4. Checking the axial clearance of the rotor................................................................................ 455
5. Checking the clearance between the impeller shaft and the bearing..................................... 456
6. Checking the radial clearance of the rotor............................................................................... 456
Chapter X Electronic Control EGR System.......................................................................................457
Section I General....................................................................................................................................457
Section II On-board Maintenance ..........................................................................................................458
Chapter XI Electrical System ..............................................................................................................462
Section I Storage Battery .......................................................................................................................462
1. Storage Battery Performance Parameters .............................................................................. 462
2. Preparing Electrolyte ............................................................................................................... 463
3. Charging the Storage Battery.................................................................................................. 464
4. Checking the Storage Battery Remaining Capacity................................................................ 466
Section II Starting System......................................................................................................................468
1. General.................................................................................................................................... 468
2. On-board Maintenance............................................................................................................ 470
Section III Charging System...................................................................................................................473
1. Generator................................................................................................................................. 473
2. Diagnosis................................................................................................................................. 475
3. On-board Maintenance............................................................................................................ 477
Chapter XII Exhaust System ...............................................................................................................481
Section I General....................................................................................................................................481
Section II On-board Maintenance ..........................................................................................................481
Section III Front Exhaust Pipe................................................................................................................482
Appendix...............................................................................................................................................486
Appendix I Engine Malfunction Code.....................................................................................................486
Appendix II Conversion Table of Common Measurement Units for Engines.........................................499

Chapter I Introduction
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
1
Chapter I Introduction
Section I How to Use This Manual
1. Index
The content (index) of this manual will guide you to the item to be repaired. For the convenience of
finding information, the title of each chapter is given at the header of the singular page.
2. Preparations
Preparations list the special service tools, special service materials, sealant and lubricating oil that
should be prepared before operation and their functions.
3. Repair Procedures
Most repair processes begin with an overview illustration which identifies all parts and how they are
disassembled and assembled (refitted) in sequence. For example, see Fig. 1-1-1 for the disassembly /
assembly schematic diagram for the oil pump parts.
Fig. 1-1-1 Disassembly /Assembly Schematic Diagram for Oil Pump Parts
The repair procedure is introduced in the following sequence:
Cylinder body
Outer rotor
Front oil seal
assembly of
crankshaft
Removing sequence
①Oil pump
②Rubber seal ring
③Outer rotor
Assembly sequence
Assembly in the sequence reverse to
disassembly.
Oil pump mounting
assembly
Rubber seal
ring

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
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Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
(1) The schematic diagram shows what to do and where to do it, see Fig. 1-1-2.
(2) The title of the work task shows the content of repair.
(3) Explain in detail how to carry out the work content and provide other technical information, such as
specification and attention, note, etc., and the quantity and dimensions of fasteners.
For example:
Schematic diagram
What to do and where to do it
Title of work task: the content of repair
Mounting the clutch assembly
Using special service tools to mount the clutch
assembly.
Front bearing installer: 5-8522-0024-0
Tool No.
Detailed explanation: how
to carry out the work.
Torque: 23 N·m ±3 N·m Specification
Check the assembly quality.
Fig. 1-1-2 Mounting the Clutch Assembly
This form provides a shortcut for the experienced technical personnel to obtain the data required. The
work task title on the top makes the content of repair clear at a glance, while the content below it
provides the detailed explanation. Important specification, attention, warning and caution always stand
out in ―boldface‖.
4. References
To improve lookup and work efficiency, this manual adopts references as few as possible; however, the
Section No. and Page No. are given when necessary.
5. Specifications
Specifications are listed separately when necessary. There is no need to leave your work for looking up
specifications. The specifications are listed at the end of every section for quick reference.
6. Warning, Attention, Caution, Prompt:
―Warning!‖ is shown in ―boldface‖ to remind the possibility of personnel injury to you or others.
―Attention!‖ is shown in ―boldface‖ to remind the possibility of damage to parts being repaired..
―Caution!‖ is shown with ―boldface‖ to remind the possibility of damage to diesel engine.

Chapter I Introduction
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
3
―Prompt‖ is separated from the text and is shown in ―boldface‖; it provides additional information to
help you carry out the repair more effectively.
7. Marks
Disassembling: separate the integrity (the whole engine) into constituent parts.
Removing: separate the engine (the components) and detach the parts.
Assemble (refitting, assembling): assembling parts or components into the integrity (the whole
engine).
Mounting: fix parts at the specified positions (of the engine) according to certain technical
requirements.
Checking, testing: make careful checking, examination and determination in order to find (the
engine) problems (or malfunctions).
Washing, cleaning: clean up; without dust, oil stain, etc.
Tightening, fastening: make an object rotate to fix or secure it; the object is fixed or secured by
outer force.
Remind the need to use special tools while performing disassembling or assembling.
Remind the need to apply engine oil for lubrication (see Table 2-6-7 for lubrication positions before
assembling the engine).
Remind the need to apply sealant (see Table 2-6-8 for sealant-applied positions while assembling
the engine).
8. Measurement Units
The measurement units adopted in this manual are mainly SI units (the standard international unit).
For example:
Torque: N·m;
Force: N;
Power: W, kW;
Length: μm, mm, m, km;
Rotating speed: r/min;
Pressure, pressure strength: Pa, kPa, MPa;
Temperature: °C
Volume: mL, L;
Mass: g, kg;
Electric current:A;
Electric resistance: Ω, kΩ;

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
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Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Voltage: V;
Plane angle: °;
Noise: dB/A;
Time: s, min, h.
Section II Main Contents of Civilized Production for Maintenance
Civilized production is aimed at creating a good producing condition and working environment to
improve maintenance quality, ensure personnel and device security, and improve labor efficiency. The
main contents are as follows:
(1) Design and decorate the workshop according to requirements for maintenance and labor protection,
such as ventilation, lighting, fire control, noise control, etc.
(2) Keep the workshop and work place clean.
(3) Equipping special maintenance and examination tools and avoiding forced disassembly and
assembly.
(4) Store the components and parts of the engine assembly at the specified rack in the specified
storeroom in order, and prevent fire and theft.
(5) Keeping all kinds of maintenance facilities, tools, fixtures, and measuring instruments in good
condition.
(6) Proving mature maintenance process regulations, technical documents and standards, and
performing work according to the procedures and specifications.
(7) Keep maintenance records, and comply with the handover procedures. The repair records contain:
①Main problems (serious wear or accidental damage) detected after the engine is disassembled; ②
Records and conclusions of technical appraisal for major parts; ③Registration of replacing with new
pieces and repaired pieces; ④Results of quality tests during and after repair; ⑤Records of test data.
Vehicle takeover records contain the following filled items: ①Who and when to send the vehicle for
repair; ②Last repair and replacement conditions; ③The working condition of vehicle after the last repair;
④The maintenance condition of the engine, and malfunctions that ever happened; ⑤The damage
condition of the engine and the name of the exterior missing parts; ⑥The item to be repaired and the
deadline required by the sender and agreements concerning fee.
(8) The maintenance personnel should keep clean and tidy appearances, behave in good manner, work
in solidarity and cooperation, observe disciplines and service with enthusiasm.
Section III Fire Control Measures for Maintenance Workshop
(1) Flammable materials such as vehicles, diesel, ethyl alcohol, oil paint and refrigerant should be kept
away from fire and heat sources.
(2) Used cleaning cloth, waste cotton fabric, oil stained gloves, packaging cartons of parts and plastic
packaging bags should be collected and placed in the safe place or metallic container.
(3) No smoking, no eating in the workshop.
(4) The workshop should be equipped with fire fighting equipment and tools, and special persons should
be assigned to manage them. Fire control education should be implemented regularly, and a fire control
supervisor should be specified.

Chapter I Introduction
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
5
Section IV Dress Security Requirements for Maintenance Personnel
(1) The maintenance personnel should wear work wear during working.
(2) The personnel with long hair or a long braid should wear a working hat, and the braid should be
wrapped into the hat to prevent from being involved into the rotating machine.
(3) Do not open your clothes or loosen the cuff when carrying out repair; do not wear gloves when
operating the rotating machine.
(4) When there are strong light, or metal debris splashing in the work area, and when working on the
place in contact with strong acid, refrigerant and other chemicals, wear safety goggles.
Section V Main Contents of Maintenance Process Regulation
The contents of the maintenance process regulation for the engine are as follows:
(1) The procedure sequence and detailed operation contents to accomplish the maintenance work.
(2) The tools, equipment and correct operating methods that should be adopted to ensure the
maintenance quality and operation security.
(3) Quality test items and test facilities that should be used during maintenance.
(4) Quality requirements that should be met in the process of maintenance.
(5) Norm of the working hour to accomplish the maintenance work.
Section VI Identification Marks
Serial number of the engine
The serial number of GW4D20/GW4D20B turbocharged diesel
engine is stamped on the left cylinder body, as shown in Fig.
1-6-1.
Fig. 1-6-1 Serial Number
Identification of Diesel Engine
Position of
identification mark
Machine code
Asterisk
Year
Month
Serial number
Asterisk

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
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Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Section VII General Repair Instructions
Fig. 1-7-1 Removing the Negative (-) Cable of
Battery
Fig. 1-7-2 Precoating Sealant on Parts
Fig. 1-7-3 Torque Spanner
1. When carrying out repair, use the baffle, seat and
floor mat to keep the vehicle clean and intact and
prevent damage.
2. During disassembly, keep parts in a proper order so
as to facilitate reassembly.
3. The rules that should be observed during repair.
3.1 Before performing electrical repair, disconnect the
negative (-) cable from the storage battery, as shown in
Fig. 1-7-1.
3.2 If it is necessary to disconnect the storage battery
during check and repair, the negative (-) cable of the
storage battery should be disconnected first, as it
connects to the vehicle body and constitutes the earth
wire.
3.3 To prevent damage to the battery terminal, loosen
the fixed nut of the cable connection terminal and raise
the cable connection terminal without twisting or prying
it.
3.4 Clean the battery terminal and the cable connection
terminal with special cleaning cloth; do not scrape them
with a file or other abrasive objects.
3.5 Unscrew the nut when connecting the cable terminal
to the battery terminal, and screw it after installation. Do
not use a hammer to tap the cable terminal onto the
battery terminal.
3.6 Be sure to properly cover the positive pole (+) of the
storage battery.
4. Check the hose and conductor connector to ensure
secure and correct connections.
5. Non-reusable parts: as for splint pins, gaskets, O
rings, oil seals, etc., replace them with new parts.
6. Precoated parts: refer to parts that are coated with
sealant in the factory, bolts and nuts, etc., as shown in
Fig. 1-7-2.See Fig. 2-6-8 for positions to coat sealant on
engine parts,.
6.1 If a precoated part is re-tightened, loose or loosened
in any way, it must be recoated with the specified
sealant.
6.2 When reusing a precoated part, clear the old sealant
away from the part surface or the threaded hole, and
clean the surface or the hole with compressed air. Then
apply the specified sealant to the specified position, as
shown in Fig. 1-7-2.
Sealant
Indicating torque spanner
Scale indication torque spanner

Chapter I Introduction
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
7
Fig. 1-7-4 Jack
Fig. 1-7-5 Pull Apart Fuel Return Hose and
Vacuum Hose
Fig. 1-7-6 Checking the Conductor Connector
7. When necessary, apply sealant to gaskets to prevent
leakage.
8. Strictly observe all specifications for bolt tightening
torques (see Table 2-6-1, 2-6-2), and use the torque
spanner according to technical requirements, as shown
in Fig. 1-7-3.
9. Special repair tools, instruments (see Table 2-11-1)
and special repair materials (see Table 2-6-8, 2-6-9)
may be used, depending on the repair. Be sure to use
special repair tools and special repair materials as
required according to situations, and strictly observe
correct operation specifications. A list of special repair
tools and special repair materials can be found in
"Chapter II Technical Information of Engine‖ in this
manual.
10. Be sure to take care when jacking up and
supporting the vehicle. Be sure to lift and support the
vehicle at the proper locations.
10.1 If the vehicle is to be jacked up only at the front or
rear end, be sure to block the wheels at the opposite
end in order to ensure safety.
10.2 Be sure to hold the vehicle with a support after it is
jacked up. It is extremely dangerous to do any work on
a vehicle raised on a jack alone, even for a small job
that can be finished quickly.
11. Observe the following precautions to prevent
damage to parts:
11.1 Non-specialized personnel should not open the
cover or housing of the electric control unit (ECU).
11.2 When disconnecting the fuel return hose
component and the vacuum hose of the fuel injector,
hold the end but not the middle of the hose, as shown in
Fig. 1-7-5.
11.3 To pull apart the circuit connectors, pull the
connector itself but not the wires, as shown in Fig.
1-7-6.
11.4 Be careful not to drop precision parts, EFI system
elements (such as the oil injector, sensor, ECU, etc.) off,
as shown in Fig. 1-7-7.If they are dropped, they should
be replaced with new parts.
11.5 Never use an impact spanner to disassemble or
mount a temperature sensor or other sensors which has
specific torque requirements.
Hydraulic jack
Scissor jack
Incorrect
Correct
Incorrect
Correct
Correct

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
8
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Fig. 1-7-7 Electric Control System Elements
of Engine
Section VIII Precautions for
Maintenance Operation
If the vehicle is equipped with the mobile
communication system, such as the two-way wireless
communication equipment and cellular phone, the
following precautions should be observed:
(1) Install the communication antenna away from the
ECU and sensors of automotive electronic system as
far as possible.
(2) The antenna feeder should be installed more than
20 cm away from the ECU and sensors of automotive
electronic system. For the positions of the ECU and
sensors, please refer to the related sections.

Chapter II Technical Information of Engine
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
9
Chapter II Technical Information of Engine
Fig. 2-1-1 Cylinder Head and Cylinder Body
Fig. 2-1-2 Crank and Connecting Rod
Mechanism
Fig. 2-1-3 Valve Actuating Mechanism
Section I Structure of Engine
The diesel engine is a kind of complex machinery that
transforms the thermal energy of fuel into mechanical
power.Although there are various types of diesel engine
with different structures, they all contain the following
mechanisms and systems:
1. Cylinder head and cylinder body
For cylinder head and cylinder body, see Fig. 2-1-1.
The function of the cylinder head is to seal the upper
part of the cylinder and make the upper part of the
cylinder and piston crown constitute the combustion
chamber. The cylinder head is mounted with the intake
valve, exhaust valve, rocker arm, hydraulic lash
adjuster, intake/exhaust camshaft assembly, oil injector,
etc., and is laid with intake and exhaust pipelines, and
cooling water jackets. The cylinder body constitutes the
cylinder and is used to mount and support all
mechanisms and systems of the diesel engine; it is the
foundation and framework of the diesel engine.
2. Crank and Connecting Rod Mechanism
For the crank and connecting rod mechanism of engine,
see Fig. 2-1-2.
The crank and connecting rod mechanism can
accomplish the interconversion between the linear
reciprocating motion of piston (in cylinder) and the
rotation motion of crankshaft, and thereby output the
propulsion produced by gas combustion through the
crankshaft as the output power, and ensure the
fulfillment of working cycles of the diesel engine. The
crank and connecting rod mechanism mainly consists of
the piston, connecting rod, crankshaft, flywheel, etc.
3. Valve Actuating Mechanism and
Intake/Exhaust System
The valve actuating mechanism, intake and exhaust
systems are as shown in Fig. 2-1-3, 2-1-4.
The functions of the valve actuating mechanism and
intake and exhaust systems are opening and closing the
intake valve and exhaust valve in time to ensure the
cylinder to intake flesh and clean air as much as
possible and discharge exhaust gas as clear as
possible timely. It mainly consists of the valve
components (the intake and exhaust valve, valve
pin/clip, valve spring, spring seat, valve oil seal, etc.),
transmission mechanism (the belt, pulley,
intake/exhaust camshaft assembly, rocker arm,
Cylinder
head
Cylinder body
Connecting
rod
Crankshaft
Connecting
rod cap
Camshaft
assembly
Intake/exhaust
valve component

MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
10
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Fig. 2-1-4 Intake/Exhaust System
hydraulic lash adjuster, etc.), air filter, intake/exhaust
pipelines, intake/exhaust manifolds, etc. The electric
control EGR valve and EGR cooler contained in the
intake/exhaust systems carry out the exhaust gas
recirculation process, and effectively limit the Nox
constituent in emissions.
Fig. 2-1-5 Turbocharging System
4. Turbocharging System
The turbocharging system of engine is as shown in Fig.
2-1-5.
The function of the turbocharging system is to compress
the air from the air filter through the turbocharger and
then sent the compressed air into cylinder by use of the
exhaust gas energy. Although the working volume of the
cylinder does not change, the air density increases after
compression, and therefore the volume of the actual
intake air increases. In this way, the fuel injected into the
cylinder increases and the fuel burns more fully, and
therefore the power per liter and output power of the
diesel engine are improved.
Fig. 2-1-6 Fuel Supply System
5. Fuel Supply System
The fuel supply system of engine is as shown in Fig.
2-1-6.
According to the work requirements of the diesel
engine, the fuel supply system regularly injects diesel
into the combustion chamber at a specified quantity and
pressure to provide necessary conditions for sufficient
combustion of diesel; at the same time, it adjusts the oil
supply quantity according to the loading condition of the
diesel engine, and ensures a steady output power. The
fuel supply system mainly consists of the fuel tank, fuel
filter, fuel delivery pump, high pressure fuel pump, high
pressure fuel rail, fuel injector, high/low pressure fuel
pipe, and all kinds of sensors, etc.
Cylinder head
installation assembly
Cylinder body
Turbocharger assembly
Oil return hose
component
Oil inlet pipe
component
High
pressure
oil rail
assembly
Oil
injector
assembly
High pressure oil
pump assembly
Cylinder head
Air intake manifold
Cylinder head
installation assembly
Exhaust manifold