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6A1 – 30 4JB1/4JB1T/4JB1TC/4JG2 - ENGINE

TIMING BELT (4JG2 Belt Type)

REMOVAL

Preparation:

• Disconnect battery ground cable.

• Drain coolant.

1. Cooling Fan Assembly

• Remove clamp nut, and remove cooling fan asm,

distant pipe, and fan pulley.

2. Fan Shroud

• Removal reservoir tank hose and fan shroud.

3. Power Steering Pump Drive Belt (P/S Model)

• Loosen power steering pump idle pulley lock nut and

adjust bolt, and remove the drive belt.

4. A/C Compressor Drive Belt (A/C Model)

• Loosen A/C compressor idle pulley lock nut and adjust

bolt, and remove the drive belt.

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Table of Contents4
Service Information Contents5
Table of Contents5
Troubleshooting Contents6
Hard Starting7
- Starter Inoperative7
- Starter Motor Operates but Engine Does Not Turn over7
- Engine Turns over but Does Not Start8
- Quick-On Start System9
Unstable Idling10
Insufficient Power11
Excessive Fuel Consumption13
Excessive Oil Consumption13
Overheating14
White Exhaust Smoke14
Dark Exhaust Smoke15
Oil Pressure Does Not Rise15
Abnormal Engine Noise16
- Engine Knocking16
- Gas Leakage Noise16
- Continuous Noise16
- Slapping Noise17
Engine Cooling Trouble18
Engine Electrical Part Trouble19
Engine Has Less than Normal Power24
Turbocharger24
- Blue or Black Smoke26
- Excessive Turbocharger Noise30
- Excessive Rotating Part Wear32
- 4JB1, 4JB1TC, 4JG2, Oil Filter and Oil Cooler33
Lubrication Chart33
Main Data and Specifications34
- Engine Cooling36
- Starting System36
- Charging System37
Engine Mechanical38
Service Standard38
- Model Identification42
- Air Cleaner42
- Dust Fouled Element42
Servicing42
- Lubricating System43
- Main Oil Filter (Cartridge Type Paper Element) Replacement Procedure43
- Fuel Filter Water Draining Procedure44
- Replacement Procedure44
Fuel System44
- Engine Coolant Change Procedure45
- Cooling System45
- Coolant Level45
- Air Bleeding45
- Cooling System Inspection47
- Radiator Cap Inspection47
- Thermostat Operating Test47
- Drive Belt Adjustment48
- Cooling Fan Pulley Drive Belt48
- Compressor Pulley Drive Belt48
- Power Steering Oil Pump Pulley Drive Belt48
- Engine Control49
- Idling Speed Inspection49
- Idling Speed Adjustment49
- Accelerator Control Cable Adjustment49
- Valve Clearance Adjustment50
- Injection Timing Adjustment51
- Quick-On Start System Inspection Procedure53
- Quick-On Start II System (4JB1 / 4JB1T / 4JB1TC Only)53
- Compression Pressure Measurement53
- Quick-On Start III System (4JG2 Only)54
- Cylinder Head Cover, Cylinder Head Rocker, Shaft Braker55
Fixing Torque55
- Crankshaft, Bearing Cap, Connecting Rod Bearing Cap, Crankshaft Damper Pulley, Flywheel, Oil Pan56
- Timing Pulley Housing, Timing Pulley, Timing Gear, Camshaft Oil Seal Retainer57
- Cooling System and Lubrication System58
- Intake Manifold, Exhaust Manifold, Exhaust Pipe59
- Engine Electricals61
- Engine Fuel62
- Engine Mounting Bracket63
Special Tools64
- General Engine Mechanical Contents68
- Cylinder Head69
  - Cylinder Head Disassembly69
  - Cylinder Head Clean70
  - Cylinder Head Inspection and Repair70
  - Hot Plug Depression (4JG2 Only)71
  - Combustion Chamber Inspection (4JG2 Only)72
  - Hot Plug Inspection72
  - Hot Plug Installation (4JG2 Only)72
  - Hot Plug Removal (4JG2 Only)72
  - Cylinder Head Reassembly73
  - Heat Shield Installation (4JG2 Only)73
  - Heat Shield Removal (4JG2 Only)73
- Valve Spring, Valve Guide Oil Seal, Valve Guide, Push Rod77
  - Valve Spring, Valve Guide Oil Seal, Valve Guide, Push Rod Disassembly77
  - Valve Guide78
  - Valve Spring78
  - Valve Spring, Valve Guide Oil Seal, Valve Guide, Push Rod Inspection and Repair78
  - Valve Guide Replacement80
  - Valve Thickness80
  - Valve Contact Width81
  - Valve Depression81
  - Valve Seat Insert Replacement81
  - Push Rod Curvature82
  - Valve Seat Insert Correction82
  - Valve Spring, Valve Guide Oil Seal, Valve Guide, Push Rod Reassembly83
- Camshaft, Tappet84
  - Camshaft, Tappet Disassembly84
  - Camshaft, Tappet Inspection and Repair85
  - Camshaft Bearing Replacement86
  - Tappet87
  - Tappet Reassembly87
- Rocker Arm Assembly91
  - Rocker Arm Disassembly91
  - Rocker Arm Inspection and Repair91
  - Rocker Arm Shaft Run-Out93
- Oil Pump94
  - Oil Pump Disassembly94
  - Oil Pump Inspection and Repair95
  - Oil Pump Reassembly96
- Crankshaft98
  - Crankshaft Disassembly98
  - Crankshaft Inspection and Repair99
  - Run-Out101
  - Crankshaft Bearing Selection102
  - Crankshaft Reassembly103
  - Timing Belt108
  - Crankshaft Damper Pulley110
  - Injection Pump112
- Piston and Connecting Rod114
  - Piston and Connecting Rod Disassembly114
  - Piston and Connecting Rod Inspection and Repair115
  - Piston and Piston Ring115
  - Piston and Connecting Rod Reassembly120
- Cylinder Block123
  - Cylinder Block Disassembly123
  - Cylinder Block Inspection and Repair124
  - Cylinder Liner Projection Inspection124
  - Flatness124
  - Cylinder Liner Bore Measurement125
  - Cylinder Liner Grade Selection125
  - Cylinder Body Bore Measurement126
  - Cylinder Liner Installation127
  - Cylinder Block Reassembly128
  - 4JB1/4JB1T/4JB1TC/4JG2-Engine Contents136
- General Description137
- Engine Mount (RH)139
  - Engine Mount (RH) Removal139
  - Engine Mount (RH) Installation140
- Engine Mount (LH)141
  - Engine Mount (LH) Removal141
  - Engine Mount (LH) Installation142
- Inlet Manifold143
  - Inlet Manifold Removal143
  - Inlet Manifold Installation144
- Exhaust Manifold145
  - Exhaust Manifold Removal145
  - Exhaust Manifold Installation146
- Oil Cooler147
  - Oil Cooler Removal147
  - Oil Cooler Inspection148
  - Oil Cooler Installation148
- Oil Filter Cartridge149
  - Oil Filter Cartridge Installation149
  - Oil Filter Cartridge Removal149
- Cylinder Head Cover150
  - Cylinder Head Cover Installation150
  - Cylinder Head Cover Removal150
- Rocker Arm Shaft Assembly152
  - Rocker Arm Shaft Installation152
  - Rocker Arm Shaft Removal152
- Valvestem Oil Controller and Valve Spring155
  - Valvestem Oil Controller and Valve Spring Removal155
  - Valvestem Oil Controller and Valve Spring Installation156
  - Timing Gear (4JB1, 4JB1TC, 4JG2 Gear Type)158
  - Timing Gear (4JB1, 4JB1TC, 4JG2 Gear Type) Removal158
  - Idler Gear "A" End Play Measurement159
  - Timing Gear Backlash Measurement159
  - Timing Gear (4JB1, 4JB1TC, 4JG2 Gear Type) Installation161
  - Timing Belt (4JG2 Belt Type)165
  - Timing Belt (4JG2 Belt Type) Removal165
  - Timing Belt (4JG2 Belt Type) Installation167
  - Cylinder Head and Gasket Removal172
- Cylinder Head Assembly and Gasket172
  - Cylinder Head and Gasket Installation176
  - Tension Adjustment181
- Oil Pan183
  - Oil Pan Removal183
  - Oil Pan Installation185
- Oil Pump Assembly186
  - Oil Pump Removal186
  - Oil Pump Installation188
- Piston, Piston Ring and Connecting Rod189
  - Piston, Piston Ring and Connecting Rod Removal189
  - Piston, Piston Ring and Connecting Rod Installation192
- Camshaft and Tappet198
  - Camshaft and Tappet Removal198
  - Camshaft and Tappet Installation203
- Crankshaft Front Oil Seal (Gear Drive Type)206
  - Crankshaft Front Oil Seal (Gear Drive Type) Removal206
  - Crankshaft Front Oil Seal (Gear Drive Type) Installation207
- Crankshaft Front Oil Seal (Belt Drive Type)208
  - Crankshaft Front Oil Seal (Belt Drive Type) Removal208
  - Crankshaft Front Oil Seal (Belt Drive Type) Installation209
- Crankshaft Rear Oil Seal (Gear & Belt Drive Type)211
  - Crankshaft Rear Oil Seal (Gear & Belt Drive Type) Removal211
  - Crankshaft Rear Oil Seal (Gear & Belt Drive Type) Installation215
- Flywheel and Pilot Bearing218
  - Flywheel and Pilot Bearing Removal218
  - Flywheel and Pilot Bearing Installation219
- Crankshaft and Main Bearings220
  - Crankshaft and Main Bearings Removal221
  - Crankshaft and Main Bearings Installation225
- Engine Assembly231
  - Engine Removal231
  - Engine Installation238
  - Engine Cooling Contents244
  - Engine Cooling General Description244
  - Radiator245
  - Thermostat245
  - Water Pump245
  - Anti-Freeze Solution248
- On-Vehicle Service249
  - Water Pump Removal249
  - Water Pump Inspection250
  - Water Pump Installation251
  - Thermostat Inspection253
  - Thermostat Removal253
  - Thermostat Installation254
  - Radiator Removal255
  - Radiator Inspection256
  - Radiator Installation257
  - Drive Belt Adjustment Inspection258
  - Engine Fuel Contents260
- General Description261
  - Fuel Flow262
  - Injection Pump263
  - Fuel Filter and Water Separator264
  - Injection Nozzle265
- Fuel Filter Assembly266
  - Fuel Filter Installation266
  - Fuel Filter Removal266
- On-Vehicle Service266
- Fuel Filter Cartrige267
  - Fuel Filter Cartrige Installation267
  - Injection Nozzle Inspection268
  - Injection Nozzle Removal268
  - Injection Nozzle Disassembly (4JG2 Engine)269
  - Injection Nozzle Inspection (4JG2 Engine)269
  - Injection Nozzle Reassembly (4JG2 Engine)270
  - Adjustment of Injection Opening Pressure (4JG2 Engine)271
  - Oil Tight Test (4JG2 Engine)271
  - Injection Nozzle Installation (4JG2 Engine)272
  - Injection Nozzle (Two Spring Nozzle Holder) (4JB1-TC Only)273
  - Injection Nozzle Disassembly273
  - Only)274
  - Reassembly and Adjustment Procedure274
  - Reassembly and Opening Pressure Adjustment (4JB1-TC274
  - Injection Nozzle Disassembly (4JBI/4JB1T Engine)282
  - Injection Nozzle Inspection and Repair (4JB1/4JB1 T Engine)282
  - Injection Nozzle Installation (4JB1/4JB1 T Engine)284
  - Injection Pump Asm (4JB1/4JB1T, 4JG2 Gear Drive Type)285
  - Injection Pump Asm (4JB1/4JB1T, 4JG2 Gear Drive Type) Removal285
- Injection Pump Assembly (Gear Drive Type)286
- Injection Pump Asm (4JB1/4JB1T, 4JG2 Gear Drive Type) Installation287
- Injection Pump Assembly (Belt Drive Type)287
  - Injection Pump Assembly (4JG2 Belt Drive Type)290
  - Injection Pump Assembly (4JG2 Belt Drive Type) Removal290
  - Injection Pump Assembly (4JG2 Belt Drive Type) Installation294
- Injection Timing Adjustment300
- Adjustment of Idling Speed301
- Injection Pump Data302
  - Test Conditions302
  - Identification Plate and Number303
- Injection Volume and Governor Performance Diagram304
- Fuel Tank314
  - Fuel Tank Removal314
  - Fuel Tank Installation315
- Fuel Gauge Unit316
  - Fuel Gauge Unit Installation316
  - Fuel Gauge Unit Removal316
- Accelerator Control Cable317
  - Accelerator Control Removal317
  - Accelerator Control Inspection318
  - Accelerator Control Installation318
- Accelerator Pedal319
  - Accelerator Pedal Installation319
  - Accelerator Pedal Removal319
- Idling Control Cable321
  - Idling Control Cable Installation321
  - Idling Control Cable Removal321
- Air Cleaner Element323
  - Air Cleaner Element Removal323
  - Air Cleaner Element Installation324
  - Battery Contents326
  - Engine Electrical Contents326
- Battery327
- Diagnosis327
- Fluid Level Check327
- General Description327
  - Visual Inspection327
  - Voltage Check327
  - Load Test328
- Battery Charging329
- On-Vehicle Service329
- Jump Starting330
  - Jump Starting with an Auxiliary (Booster) Battery330
  - Jump Starting Procedure331
- Main Data and Specifications332
- Removal and Installation of Battery332
  - Starting Circuit334
  - Starting System Contents334
  - Starting System Installation336
  - Starting System Removal336
  - Starting System Disassembly338
  - Unit Repair338
  - Armature341
  - Starting System Inspection and Repair341
  - Yoke342
  - Bearing343
  - Brush and Brush Holder343
  - Overrunning Clutch343
  - Starting System Reassembly344
  - Magnetic Switch345
  - Charging System Contents346
  - Generator347
  - Charging Circuit348
  - General On-Vehicle Inspection349
  - Generator Removal350
  - Generator Installation351
  - Generator Disassembly354
  - Generator Inspection and Repair355
  - Rotor356
  - Stator Coil356
  - Brush357
  - Diode357
  - IC Regulator358
  - Vacuum Pump359
  - Generator Reassembly360
  - Charging System Disassembly362
  - Charging System Inspection and Repair364
  - Charging System Reassembly366
  - Output Characteristic366
  - QOSII Preheating System (4JB1/4JB1T/4JB1TC Only)368
  - QOS II Timing Chart369
  - System Diagram369
  - Gow Plug370
  - Inspection on QOSII System Operation Thermo Switch370
  - QOSII System Troubleshooting371
  - QOSIII Preheating System (4JG2 Only) Contents374
  - QOS III Flow Chart376
  - QOS III Block Chart377
  - Inspection on QOSIII System Operation378
  - Glow Plug379
  - Thermo Sensor379
  - Charge Relay380
  - Dropping Resistor380
  - Glow Plug Relay380
  - Exhaust Gas Recirculation (EGR) System Contents382
- General Description383
- EGR System Operation384
- EGR System Wiring Diagram384
  - Exhaust Gas Recirculation (EGR) System Check385
  - EGR System Inspection386
  - Engine Exhaust Contents388
- General Description389
  - General Export389
  - Model ’91/542B (Euro 2)389
- Three Way Catalytic Converter390
- Front Exhaust Pipe391
- Front Exhaust Pipe Removal391
- On-Vehicle Service391
  - Exhaust Brake Unit Inspection392
  - Front Exhaust Pipe Installation392
  - Turbocharger Contents394
  - Turbocharger Main Data and Specifications395
- General Description396
- Identification of Unit397
- Precautions397
- Turbocharger Servicing397
  - Disassembly Steps398
  - Turbocharger Disassembly398
  - Turbocharger Inspection and Repair400
  - Reassembly Steps402
  - Turbocharger Reassembly402
- Ihi Service Network404

Brand	Isuzu
Model	NPR 4J Series
Category	Engine
Language	English

Isuzu NPR 4J Series User Manual

Table of Contents

Questions and Answers:

Isuzu NPR 4J Series Specifications

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