Mitsubishi S4Q

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Service Manual Mitsubishi SQ-Series diesel engines
Version 08/2004
ENGLISH
CAUSES OF ENGINE PROBLEMS AND
REMEDIES TROUBLESHOOTING
(• Refer to the separate troubleshooting chart.)
Problems/Symptoms
Hard starting
Glow plugs do not produce red heat Glow plugs do produce red heat to fast
Not enough
power
Exhaust
smoke
abnormal
Engine produces loud knocking sound Engine produces abnormal noice Engine produces irregular combustion sound
Engine
hunts
Engine turns
Cranking speed low
Engine
does not
turn
Small amount of exhaust smoke Large amount of white exhaust smoke Large amount of black exhaust smoke At idling
In
operation
At idling In operation
Possible causes
No exhaust smoke Small amount of exhaust smoke Large amount of exhaust smoke Engine can be cranked manually Engine can not be cranked manually White Black
Fuel system
No fuel to injection pump ⊗⊗__ __ __ __ __ __ ⊗ __ __ __ __ __ __ __ __ __ __
Greater variance of fuel
injection quantity
__ __ ⊗ __ __ __ __ __ __ __ ⊗⊗__ ⊗⊗__ ⊗⊗⊗
Injection pump oil seals
defective
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Insufficient fuel injection
volume
⊗⊗__ __ __ __ __ __ ⊗ __ __ __ __ __ __ __ __ __ __
Excessive fuel injection
volume
__ __ __ __ __ __ __ __ __ __ __ __ __ ⊗ __ __ __ __ __
Injection nozzle defective __ __ ⊗ __ __ __ __ __ __ __ ⊗⊗⊗⊗⊗__ ⊗⊗⊗
Excessive fuel return from
injection nozzles
__ ⊗ __ __ __ __ __ __ ⊗ __ __ __ __ __ __ __ ⊗⊗__
Injection timing is too
advanced
__ __ ⊗ __ __ __ __ __ __ ⊗ __ __ ⊗⊗⊗__ __ __ __
Injection timing is too retarded __ __ ⊗ __ __ __ __ __ __ __ ⊗⊗__ __ __ __ ⊗⊗__
Engine speed is too low __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ⊗ __
Failure to stop __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Improper fuel __ __ ⊗ __ __ __ __ __ __ ⊗⊗⊗⊗⊗⊗__ __ __ __
Fuel viscosity is too high
⊗⊗__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Lubricating system
Improper oil quality __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Oil viscosity is too high __ __ __ __ ⊗ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Oil viscosity is too low ________ __ __ ____________ ⊗ __ __ __ __ __ __
Oil pressure does not rise __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Oil leaks
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Excessive pumping up of oil ________ __ __ ____________ ⊗⊗⊗__ __ __ __
Clogged oil filter __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
Oil pressure switch or lamp
defective
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __