Isuzu 4JB1 User Manual

SERVICE INFORM
ATION 00 – 3
1.
HARD STARTING
1. STARTER INOPERATIVE
Checkpoint Possible cause Correction
Loos
e battery cable terminal poor
connections due to rusting
Clean and/or retighten the battery
cable terminal
Batter
y discharged or weak Recharge or replace the battery
Battery
F
an belt loose or broken Adjust or replace the fan belt
F
usible link Fusible link shorted Replace the fusible link
Star
ter switch Defective starter switch or starter relay Replace the starter switch or the
Starter relay
Def
ective magnetic switch or starter relay Repair or replace the magnetic switch
Starter m
otor
Defective starter motor Repair or replace the starter motor
2. STARTER MOTOR OPERATES BUT ENGINE DOES NOT TURN OVER
Loos
e battery cable terminal Clean and/or retighten the battery
cable terminal
Poor
connections due to rusting Recharge or replace the battery
Batter
y discharged or weak Recharge or replace the battery
Battery
F
an belt loose or broken Adjust or replace the fan belt
Def
ective pinion gear Replace the pinion gear
Def
ective magnetic switch Repair or replace the magnetic switch
Star
ter
Brush wear, Weak brush spring Replace the brush and/or the brush
spring
Engine
Piston, crank bearing seizure, or other
damage
Repair or replace the related parts

Isuzu 4JB1 Specifications

General

Displacement	2.8 L (2771 cc)
Bore x Stroke	93 mm x 102 mm
Compression Ratio	18.4:1
Fuel System	Indirect Injection
Aspiration	Naturally Aspirated
Cooling System	Water-cooled
Engine Type	Inline 4-cylinder diesel
Max Power	85 hp (63 kW) at 3600 rpm
Valve Train	OHV

Summary

1. HARD STARTING

1. STARTER INOPERATIVE

Troubleshooting guide for a non-operational starter motor.

2. STARTER MOTOR OPERATES BUT ENGINE DOES NOT TURN OVER

Troubleshooting guide when the starter motor runs but the engine doesn't.

3. ENGINE TURNS OVER BUT DOES NOT START

FUEL IS NOT BEING DELIVERED TO THE INJECTION PUMP

Diagnosing fuel delivery issues to the injection pump.

FUEL IS BEING DELIVERED TO THE INJECTION PUMP

Troubleshooting issues when fuel is delivered but engine fails to start.

4. QUICK-ON START SYSTEM

GLOW PLUGS ARE RECEIVING POWER

Troubleshooting steps when glow plugs have power.

GLOW PLUGS ARE NOT RECEIVING POWER

Troubleshooting steps when glow plugs lack power.

2. UNSTABLE IDLING

Idling system

Diagnosing and correcting unstable engine idling issues.

3. INSUFFICIENT POWER

Air cleaner

Troubleshooting insufficient power caused by the air cleaner.

Fuel system

Troubleshooting insufficient power due to fuel system issues.

Injection nozzle

Troubleshooting insufficient power caused by the injection nozzle.

4. EXCESSIVE FUEL CONSUMPTION

5. EXCESSIVE OIL CONSUMPTION

6. OVERHEATING

Cooling water

Thermostat

7. WHITE EXHAUST SMOKE

Fuel

Fuel injection timing

Inlet and exhaust valve Valves seals

8. DARK EXHAUST SMOKE

Air cleaner

Injection pump

9. OIL PRESSURE DOES NOT RISE

Engine oil

Oil filter

Oil pump

10. ABNORMAL ENGINE NOISE

1. ENGINE KNOCKING

Troubleshooting abnormal engine noise: engine knocking.

2. GAS LEAKAGE NOISE

Troubleshooting abnormal engine noise: gas leakage.

3. CONTINUOUS NOISE

Troubleshooting abnormal engine noise: continuous noise.

4. SLAPPING NOISE

Troubleshooting abnormal engine noise: slapping noise.

11. ENGINE COOLING TROUBLE

Engine overheating

Troubleshooting engine cooling trouble: overheating.

Engine overcooling

Troubleshooting engine cooling trouble: overcooling.

Too long engine warm-up time

Troubleshooting engine cooling trouble: long warm-up.

12. ENGINE ELECTRICAL PART TROUBLE

STARTER DOES NOT RUN

Troubleshooting electrical issues: starter motor does not run.

13. TURBOCHARGER

1) ENGINE HAS LESS THAN NORMAL POWER

Troubleshooting turbocharger issues: engine has less than normal power.

2) BLUE OR BLACK SMOKE

Troubleshooting turbocharger issues: blue or black smoke.

3) EXCESSIVE OIL CONSUMPTION

Troubleshooting turbocharger issues: excessive oil consumption.

4) EXCESSIVE TURBOCHARGER NOISE

Troubleshooting turbocharger issues: excessive noise.

5) EXCESSIVE ROTATING PART WEAR

Troubleshooting turbocharger issues: excessive rotating part wear.

Engine Cooling

Cooling system

Radiator

Starting System

Charging System

SERVICING

AIR CLEANER

Procedures for servicing the air cleaner.

LUBRICATING SYSTEM

Main Oil Filter (Cartridge Type Paper Element) Replacement Procedure

Procedure for replacing the main oil filter.

FUEL SYSTEM

Fuel Filter

Details on fuel filter replacement and draining.

Fuel Filter Water Draining Procedure

COOLING SYSTEM

Coolant Level

Engine coolant change procedure

Cooling System Inspection

ENGINE CONTROL

Idling Speed Inspection

Procedure for inspecting engine idling speed.

Idling Speed Adjustment

Accelerator Control Cable Adjustment

VALVE CLEARANCE ADJUSTMENT

Valve Clearance (At Cold)

INJECTION TIMING ADJUSTMENT

Check the notched line on the injection pump flange

Adjust the injection pump setting angle.

COMPRESSION PRESSURE MEASUREMENT

Start the engine and allow it to idle

Set the adapter and compression gauge

QUICK-ON START II SYSTEM

QUICK-ON START III SYSTEM

Quick-On Start System Inspection Procedure

Glow Plug Terminal Voltage