Isuzu N-Series. Manual - part 300
00-12 SERVICE INFORMATION
Abnormal Engine Noise
1. Engine Knocking
Check to see that the engine has been thoroughly warmed up before beginning the troubleshooting procedure.
2. Gas Leakage Noise
3. Continuous Noise
4. Slapping Noise
Check point
Possible cause
Correction
Fuel
Fuel unsuitable
Replace the fuel
Fuel injection timing
Fuel injection timing improperly adjusted
Adjust the fuel injection timing
Injection nozzle
Improper injection nozzle starting pressure
and spray condition
Adjust or replace the injection nozzle
Compression pressure
Blown out head gasket
Broken piston ring
Replace the head gasket or the piston ring
Check point
Possible cause
Correction
Exhaust pipes
Loosely connected exhaust pipes
Broken exhaust pipes
Tighten the exhaust pipe connections
Replace the exhaust pipes
Injection nozzles and/
or glow plugs
Loose injection nozzles and /or glow plugs Replace the washers
Tighten the injection nozzles and/or the
glow plugs
Exhaust manifold
Loosely connected exhaust manifold and/
or glow plugs
Tighten the exhaust manifold connections
Cylinder head gasket
Damaged cylinder head gasket
Replace the cylinder head gasket
Check point
Possible cause
Correction
Fan belt
Loose fan belt
Readjust the fan belt tension
Cooling fan
Loose cooling fan
Retighten the cooling fan
Water pump bearing
Worn or damaged water pump bearing
Replace the water pump bearing
Alternator or vacuum
pump
Defective alternator or vacuum pump
Repair or replace the alternator or the vac-
uum pump
Valve clearance
Clearance improperly adjust
Adjust the valve clearance
Check point
Possible cause
Correction
Valve clearance
Valve clearance improperly adjusted
Adjust the valve clearance
Rocker arm
Damaged rocker arm
Replace the rocker arm
Flywheel
Loose flywheel bolts
Retighten the flywheel bolts
Crankshaft and thrust
bearings
Worn or damaged crankshaft and/or thrust
bearings
Replace the crankshaft and/or the thrust
bearings
Crankshaft and con-
necting rod bearings
Worn or damaged crankshaft and/or con-
necting rod bearings
Replace the crankshaft and/or the con-
necting rod bearings
Connecting rod bush-
ing and piston pin
Worn or damaged connecting rod bushing
and piston pin
Replace the connecting rod bushing and/
or the piston pin
Piston and cylinder
liner
Worn or damaged piston and cylinder liner
Foreign material in the cylinder
Replace the piston and the cylinder liner