Isuzu 4JA1 Workshop Manual page 16

6 – 14 TROUBLESHOOTING
10-5 Excessive turbocharger noise
The vibration noise (the air aspiration noise) occurred when turbocharger rotates, it is normal condition of the
turbocharger, no necessary any actions.
Step
1 Was the excessive
turbocharger?
2 Inspect the fixing bolts and bands.
Was any problem found?
3 Was the intake or exhaust system gasket damaged?
4 Inspect rotation parts condition.
Was the turbine wheel rotation rough?
5 Inspect the turbine wheel.
Was the turbine wheel rubbing against housing?
6 Was the turbine wheel damaged?
7 Were there carbon deposits in the turbine or
compressor housing?
8 Inspect the oil supply condition.
Was the oil feed pipe clogged?
9 Was the turbine shaft bearing worn?
10 Are any DTC stored?
11. Rotating Part Wear of Turbocharger
Step
1 Inspect engine oil.
Was it contaminated with foreign materials?
2 Was the recommended engine oil grade/viscosity
being used?
3 Was the oil feed pipe restricted?
4 Was the oil seal of turbocharger defective?
5 Was the center housing oil drain passage clogged?
6 Was there oil sludge and/or coking on the turbine
shaft?
7 Are any DTC stored?
Action
noise coming from
Action
Value(s)
the —
Go to Step 2
— Tighten the
loose parts
— Replace the
damaged
— Replace the
turbocharger.
— Replace the
turbocharger.
— Replace the
turbocharger.
— Clean or
replace the
turbocharger.
— Repair or
replace the oil
feed pipe.
— Replace the
turbocharger.
— Go to indicated
Value(s)
— Replace the
engine oil
API CD or
ISUZU
genuine/
10W–30
Go to Step 3
— Clean or
replace the oil
feed pipe
— Replace the oil
— Clean center
housing or
replace the
turbocharger
— Replace the
turbocharger
— Go to indicated
Yes No
Go to Step 10
Go to Step 3
gasket. Go to Step 4
Go to Step 5
Go to Step 6
Go to Step 7
Go to Step 8
Go to Step 9
Go to Step 10
DTC Solved
Yes No
Go to Step 2
Replace the
engine oil
Go to Step 4
seal Go to Step 5
Go to Step 6
Go to Step 7
DTC Solved