MAK M20 - Engine Speed Is Not Steady; Opaque Exhaust Gas - Engine Is Emitting Soot

Fault tracing
Remedial measures
A3.11.18.02
M20-M601C
en / 08.07.1997 BA000727 3/4
Ĺ
Engine speed is not steady
Possible cause: Remedy:
• Too much clearance in the linkage between
governor and injection pump
• Fuel line is sluggish
• Friction in the injection pumps caused by
excessive fuel feed pressure
• Injection pump plunger is temporarily
caught, is leaky or the spring is broken
• Vibration damper is defective Check the vibration damper
• Rough drive owing to wear and tear or
damaged teeth
• Governor failure see manufacturer’s instructions in book C;
Governor failures
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Opaque exhaust gas - engine is emitting soot
Possible cause: Remedy:
Pressure of injection valve is too low
Nozzles are fouled by carbon deposits
Nozzle needle is jammed or nozzle is defective
Combustion air supply is insufficient
• Air intake filter is clogged
• Charge air cooler is fouled
• Turbocharger is damaged
• Turbocharger is fouled
• Engine is retarded too far Reduce fuel filling
• Abgasgegendruck zu hoch, da freier
Exhaust gas back pressure is too high
because the exhaust ducting is clogged
• Valves are leaky For servicing the valves see,
A5.05.01.08.01.nn
• Poor combustion due to very low load, For increasing the load or change over to gas
especially at heavy fuel operation oil operation see A3.06.07.nn
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