6-24 ENGINE DIAGNOSIS (RHZ ENGINE WITH SINGLE-CONNECTOR ECM)
Condition Possible Cause Reference Item
Engine noise
Note: Before check-
ing the mechanical
noise, make sure
that:
D Injection timing is
properly adjusted.
D Specified fuel is
used.
Valve noise.
D Improper valve lash
D Worn valve stem and guide
D Weak or broken valve spring
D Warped or bent valve
Piston, ring and cylinder noise.
D Worn piston, ring and cylinder bore
Connecting rod noise.
D Worn crankpin bearing
D Worn crankpin
D Loose connecting rod nuts
Low oil pressure.
Crankshaft noise.
D Worn crankshaft journal bearing
D Worn crankshaft journal
D Loose lower crankcase
(bearing cap) bolts
D Excessive crankshaft thrust play
Engine and emission control system
out of order.
Adjust.
Replace.
Replace.
Replace.
Rebore or replace cylinder.
Replace piston and ring.
Replace.
Repair by grinding or replace
crankshaft.
Tighten nuts to specification.
Previously outlined.
Replace.
Repair by grinding or replace
crankshaft.
Tighten bolts to specification.
Replace thrust bearing.
Refer to Section 6E3.
White or blue
smoke
Intake system out of order.
D Clogged air cleaner element
D EGR throttle valve
Engine and emission control system
out of order.
D Faulty ECM
D Faulty fuel injection pump
– Pump internal damage
– Fuel injector
D Faulty intake air pressure sensor
D Faulty ECT sensor
Glow system out of order.
D Faulty glow plug
D Faulty pre post heating relay
Low compression
Other
D Improper oil level
Clean or replace.
Inspect and replace.
Inspect and replace.
Replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Previously outlined.
Adjust.
Black smoke Intake system out of order.
D Faulty turbocharger
D Clogged air cleaner element
D EGR throttle valve
Engine and emission control system
out of order.
D Faulty ECM
D Faulty fuel injector
D Faulty fuel injection pump
– Faulty fuel pressure regulator
– Pump internal damage
D Faulty MAF sensor
D Faulty IAT sensor
D Faulty ECT sensor
D Faulty TP sensor
EGR system out of order.
D Faulty EGR solenoid valve
D Faulty EGR valve
Low compression
Inspect and replace.
Clean or replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Inspect and replace.
Inspect and repair or replace EGR
system.
Inspect and repair or replace EGR
system.
Previously outlined.
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