Isuzu 4JG2 Diesel Engine Workshop Repair Service Manual

SERVICE INFORMATION 00 – 1 SECTION 00 SERVICE INFORMATION CONTENTS PAGE Troubleshooting .............................................................................................................. 00- 2 Main Data and Specifications ......................................................................................... 00-20 Service Standard .............................................................................................................. 00-23 Servicing ........................................................................................................................... 00-27 Fixing Torque .................................................................................................................... 00-38 Special Tools ..................................................................................................................... 00-47

00 – 2 SERVICE INFORMATION TROUBLESHOOTING CONTENTS PAGE Hard Starting ................................................................................................................... 00- 3 Starter Motor Inoperative ........................................................................................... 00- 3 Starter Motor Operates but Engine does not turn over ........................................... 00- 3 Engine turns over but does not start ......................................................................... 00- 4 Quick-on Start System (QOS III) ................................................................................. 00- 5 Unstable Idling ................................................................................................................. 00- 5 Insufficient Power ............................................................................................................ 00- 7 Excessive Fuel Consumption .......................................................................................... 00- 9 Excessive Oil Consumption ............................................................................................. 00- 9 Overheating ...................................................................................................................... 00-10 White Exhaust Smoke ..................................................................................................... 00-10 Dark Exhaust Smoke ........................................................................................................ 00-11 Oil Pressure Does Not Rise .............................................................................................. 00-11 Abnormal Engine Noise ................................................................................................... 00-12 Engine Knocking .......................................................................................................... 00-12 Gas Leakage noise ....................................................................................................... 00-12 Continuous noise ......................................................................................................... 00-12 Slapping noise .............................................................................................................. 00-13 Engine Cooling Trouble ................................................................................................... 00-14 Engine Electrical ............................................................................................................... 00-15 Starter does not run .................................................................................................... 00-15 Faulty Meshing or Pinion and Ring Gear ................................................................... 00-16 Magnetic Switch does not operate though starter switch is turned to “Start (ST)” ... 00-17 Pinion Meshes with ring gear but engine does not run ........................................... 00-18 Starter does not stop though starter switch is returned to “ON” .......................... 00-19

SERVICE INFORMATION 00 – 3 1. HARD STARTING Checkpoint Possible cause Correction Battery Loose battery cable terminal Poor connections due to rusting Clean and/or retighten the battery cable terminal 1. STARTER MOTOR INOPERATIVE Battery discharged or weak Recharge or replace the battery Fan belt loose or broken Adjust or replace the fan belt Fusible link Fusible link shorted Replace the fusible link Starter switch Defective starter switch or starter relay Replace the starter switch or the starter relay Starter motor Defective magnetic switch or starter relay Repair or replace the magnetic switch Defective starter motor Repair or replace the starter motor 2. STARTER MOTOR OPERATES BUT ENGINE DOES NOT TURN OVER Battery Loose battery cable terminal Poor connections due to rusting Clean and/or retighten the battery cable terminal Battery discharged or weak Recharge or replace the battery Fan belt loose or broken Adjust or replace the fan belt Starter motor Defective pinion gear Replace the pinion gear Defective magnetic switch Repair or replace the magnetic switch Brush wear, Weak brush spring Replace the brush and/or the brush spring Engine Piston, crank bearing seizuer, or other damage Repair or replace the related parrts

00 – 4 SERVICE INFORMATION Checkpoint Possible cause Correction Engine stop mechanism Defective fuel cut solenoid valve Replace the fuel cut solenoid valve 3. ENGINE TURNS OVER BUT DOES NOT START FUEL IS NOT BEING DELIVERED TO THE INJECTION PUMP Fuel Fuel tank is empty Fill the fuel tank Fuel piping Clogged or damaged fuel lines. Loose fuel line connection Repair or replace the fuel lines Retighten the fuel line connection Fuel filter Fuel filter overflow valve does not close Repair or replace the fuel filter overflow valve Clogged fuel filter element Replace the fuel filter element or the filter cartridge Fuel system Air in the fuel system Bleed the air from the fuel system Fuel feed pump Defective feed pump Repair or replace the feed pump FUEL IS BEING DELIVERED TO THE INJECTION PUMP Fuel Use of the wrong fuel Use the correct fuel Water particles in the fuel Carge the fuel Fuel system Air in the injection pump Bleed the air from the fuel system Injection nozzle Injection nozzle sticking Replace the injection nozzle Injection nozzle injection starting pressure too low Improper spray condition Adjust or replace the injection nozzle Injection pump Defective fuel injection nozzle resulting in the fuel drippage after fuel injection Replace the delivery valve Defective injection pump control rack operation Repair or replace the injection pump control rack Injection pump plunger worn or stuck Replace the injection pump plunger assembley Injection pump drive shaft seizure or other damage Replace the injection drive shaft Injection pump governor spring seizure Replace the injection pump governor spring

SERVICE INFORMATION 00 – 5 Idling improperly adjusted Adjust the idling Idling system Checkpoint Possible cause Correction Defective fast idling speed control device Repair or replace the fast idling speed control device Fast idling speed control device Accelerator control system improperly adjusted Adjust the accelerator control system Accelerator control system 2. UNSTABLE IDLING 4. QUICK-ON START SYSTEM (QOS III) PREPARATION 1. Disconnect the thermoswitch connector. 2. Determine whether or not the glow plugs are receiving power. a) Make sure that the starter switch is "OFF" b) Connect a voltmeter between one of the glow plugs and the cylinder wall. c) Move the starter switch to the "ON" position. The voltmeter needle will show the souse voltage (12V) if the glow plugs are receiving power. If the voltmeter needle does not move, the glow plugs are not receiving power. 3. Perform the troubleshooting procedure. 1. 2. 3. Replace the fusible link wire Replace the indicator light fuse Replace the indicator light bulb Glow plug indicator light does not turn on. Defective Fusible link wire Broken indicator light fuse Defective indicator light bulb 1. 2. 3. 4. Replace the fusible link wire Replace or Repair glow plug relay connector Replace or Repair glow plug connector Replace or Repair quick-on start timer connector Preheating system does not work Defective Fusible link wire shorted Defective glow plug relay connector Defective glow plug connector Defective quick-on start timer connector 1. 2. 3. Replace thermo sensor or repair wiring harness. Replace glow plug Replace timer unit Preheating time to long or to short Defective thermo sensor include defective wiring harness Defective glow plug Defective timer unit

00 – 6 SERVICE INFORMATION Checkpoint Possible cause Correction Injection timing improperly adjusted Adjust the injection timing Insufficient injection volume Adjust the injection volume Defective idle spring Replace the idle spring Defective governor lever operation Repair or replace the governor lever Regulator valve improperly adjustment Adjust or replace the regulator valve Broken plunger spring Replace the plunger spring Worn plunger Replace the plunger assembly Worn cam disc Replace the cam disc Valve clearance improperly adjusted Adjust the valve clearance Valve clearance Blown out cylinder head gasket. Worn cylinder liner. Piston ring sticking between the valve and the valve seat Replace the related parts Compression pressure Fuel system leakage or blockage Repair or replace the fuel system Fuel system Air in the fuel system Bleed the air from the fuel system Water particles in the fuel system Change the fuel Clogged fuel filter element Replace the fuel filter element or the fuel filter cartridge Fuel filter Defective fuel feed pump Repair or replace the fuel feed pump Fuel feed pump Injection nozzle sticking Replace the injection nozzle Injection nozzle Injection nozzle injection starting pressure too low Improper spray condition Adjust or replace the injection nozzle Defective delivery valve resulting in fuel drippage after fuel injection Replace the delivery valve Injection pump

SERVICE INFORMATION 00 – 7 3. INSUFFICIENT POWER Clogged air cleaner element Clean or replace the air cleaner element Air cleaner Checkpoint Possible cause Correction Water particle in the fuel Replace fuel Fuel Clogged fuel filter element Replace the fuel filter element or the fuel filter cartridge Fuel filter Defective fuel feed pump Repair or replace the fuel feed pump Fuel feed pump Injection nozzle sticking Replace the injection nozzle Injection nozzle Injection nozzle injection starting pressure too low Improper spray condition Adjust or replace the injectionn nozzle Fuel injection pipes damaged or obstructed Replace the fuel injection pipes Fuel injection pipes Defective regulating valve Repair or replace the regulating valve Injection pump Defective delivery valve Replace the delivery valve Defective timer Repair or replace the timer Worn cam disk Replace the cam disk Improper control lever operation Adjust or replace the control lever Defective injection timing Adjust the injection timing Repair or replace the injection pump timer Weak governor spring Replace the governor spring Worn plunger Replace the plunger saaembly Worn cam disk Replace the cam disk

00 – 8 SERVICE INFORMATION Checkpoint Possible cause Correction Booster compensator pipe broken or cracked Replace the booster compensator pipe Turbocharger Exhaust gas leakage from the exhaust system Air leakage from the intake system Repair or replace the related parts Defective waste gate Repair or replace the waste gare Defective turbocharger assembly Replace the turbocharger assembly Blown out cylinder head gasket. Worn cylinder liner. Piston ring sticking between the valve and valve seat Replace the related parts Compression pressure Valve clearance improperly adjusted Adjust the valve clearance Valve clearance Valve spring weak or broken Replace the valve spring Valve spring Exhaust pipe clogged Clean the exhaust pipe Exhaust system Open and improperly set adjusting screw seal Adjust and reseal the adjusting screw Full load adjusting screw seal

SERVICE INFORMATION 00 – 9 4. EXCESSIVE FUEL CONSUMPTION 5. EXCESSIVE OIL CONSUMPTION Checkpoint Possible cause Correction Engine oil Engine oil unsuitable Too mauch engine oil Replace the engine oil Correct the engine oil level Oil seal and gasket Oil leakage from the oilseal and/or the gasket Replace the oil seal and/or the gasket Air breather Clogged air breather Clean the air breather Intake and exhaust valve Worn valve stems and valve guides Replace the intake and exhaust valves and the valve springs Checkpoint Possible cause Correction Fuel system Fuel leakage Repair or replace the fuel system related parts Air cleaner Clogged air cleaner element Clean or replace the air cleaner element Idling speed Poorly adjusted idling speed Adjust the idling speed Injection nozzle Injection nozzle injection starting pressure too low Improper spray condition Adjust or replace the injection nozzle Fuel injection timing Fuel injection timing improperly Adjust the fuel injection timing Injection pump Defective Delivery valve resulting is fuel drippage after fuel injection Replace the delivery valve Turbocharger Air leakage from the turbocharger intake side Repair the turbocharger intake side Defective turbocharger assembly Replace the turbocharger assembly Valve clearance Valve clearance improperly adjusted Adjust the valve clearance Compression pressure Blown out cylinder head gasket. Worn cylinder liner. Piston ring sticking between the valve and valve seat Replace the related parts Valve spring Valve spring weak or broken Replace the valve spring

00 – 10 SERVICE INFORMATION 6. OVERHEATING 7. WHITE EXHAUST SMOKE Checkpoint Possible cause Correction Fuel Water particles in the fuel Replace the fuel Fuel injection timing Delayed fuel injection timing Adjust the fuel injection timing Compression pressure Blown out cylinder head gasket. Worn cylinder liner. Piston ring sticking between the valve and valve seat Replace the related parts Turbocharger Defective turbocharger Replace the turbocharger Inlet and exhaust valves Valves seals Defective valve seales. Worn valves stems and valve guides Replace the valve seales, the valves, and the valve guides Checkpoint Possible cause Correction Cooling water Insufficient cooling water Replace the cooling water Fan clutch Oil leakage from the fan clutch Replace the fan clutch Fan belt Fan belt loose or cracked causing slippage Replace the fan belt Radiator Defective radiator cap or clogged radiator core Replace the radiator cap or clean the radiator core Water pump Defective water pump Repair or replace the water pump Cylinder head and cylinder body sealing cap Defective searing cap resulting in water leakage Replace the sealing cap Thermostat Defective thermostat Replace the thermostat Cooling system Cooling system clogged by foreign material Clean the foreign material from the cooling system Fuel injection timing Fuel injection timing improperly adjusted Adjust the fuel injection timing

Isuzu 4JG2 Diesel Engine Workshop Repair Service Manual

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