Engine speed not steady
Component
Cause
Measure
Fuel injection equip‐
ment
Injector faulty
Replace (→ Page 97).
Speed sensor
Faulty
Contact Service.
Fuel system
Air in fuel system
Vent fuel system (→ Page 103).
ECU
Faulty
Contact Service.
Charge-air temperature too high
Component
Cause
Measure
Engine coolant
Engine coolant treatment incorrect
Check (MTU test kit).
Intercooler
Contaminated
Contact Service.
Engine room
Air-intake temperature too high
Check fans and air supply / ventilation
ducts.
Charge-air pressure too low
Component
Cause
Measure
Air supply
Air filter clogged
Check signal ring position of contami‐
nation indicator (→ Page 116).
Intercooler
Contaminated
Contact Service.
Exhaust turbocharger Faulty
Contact Service.
Coolant leaks at intercooler
Component
Cause
Measure
Intercooler
Leaking, major coolant discharge
Contact Service.
Black exhaust gas
Component
Cause
Measure
Air supply
Air filter clogged
Check signal ring position of contami‐
nation indicator (→ Page 116).
Fuel injection equip‐
ment
Injector faulty
Replace (→ Page 97).
Engine
Overloaded
Contact Service.
Blue exhaust gas
Component
Cause
Measure
Engine oil
Too much oil in engine
Drain engine oil (→ Page 121).
Oil separator or oil preseparator of
crankcase breather clogged
Replace.
Exhaust turbocharg‐
er, cylinder head, pis‐
ton rings, cylinder lin‐
er
Faulty
Contact Service.
MS15021/01E 2012-02 | Troubleshooting | 73
TIM-ID: 0000002550 - 002
