Abnormal Engine Noise; Engine Knocking; Gas Leakage Noise; Continuous Noise - Isuzu NHR 4J Series Workshop Manual

00 – 12 SERVICE INFORMATION

1. ENGINE KNOCKING

Check to see that the engine has been thoroughly warmed up before beginning the troubleshooting procedure.
Checkpoint
Fuel
Fuel injection timing
Injection nozzle
Compression pressure

2. GAS LEAKAGE NOISE

Exhaust pipes
Injection nozzles
and/or glow plugs
Exhaust manifold
Cylinder head gasket

3. CONTINUOUS NOISE

Fan belt
Cooling fan
Water pump bearing
Generator or vacuum
pump
Valve clearance

10. ABNORMAL ENGINE NOISE

Possible cause
Fuel unsuitable
Fuel injection timing improperly adjusted
Improper injection nozzle starting pressure
and spray condition
Blown out head gasket
Broken piston ring
Loosely connected exhaust pipes. Broken
exhaust pipes
Loose injection nozzles and/or glow plugs
Loosely connected exhaust manifold and/or
glow plugs
Damaged cylinder head gasket
Loose fan belt
Loose cooling fan
Worn or damaged water pump bearing
Defective generator or vacuum pump
Clearance improperly adjust
Correction
Replace the fuel
Adjust the fuel injection timing
Adjust or replace the injection nozzle
Replace the head gasket or the piston
ring
Tighten the exhaust pipe connections
Replace the exhaust pipes
Replace the washers
Tighten the injection nozzles and/or
the glow plugs
Tighten the exhaust manifold
connections
Replace the cylinder head gasket
Readjust the fan belt tension
Retighten the cooling fan
Replace the water pump bearing
Repair or replace the generator or the
vacuum pump
Adjust the valve clearances