Exhaust Gas Color Is Black (Incomplete Combustion) - Komatsu Galeo PC800-8 Shop Manual

SEN00795-02
S-7 Exhaust gas color is black (incomplete combustion)
General causes why exhaust gas color is black
• Insufficient intake of air
• Excessive injection of fuel
• Defective condition of fuel injection
• Improper selection of fuel
• There is overheating
→ See "S-14 Coolant temperature becomes too high (Overheating)"
• Controller is controlling in derate mode (limiting injection rate
(output) because of an error in electrical system)
• EGR valve is stuck open (There is much EGR gas and intake of air
is insufficient)
• EGR gas pressure piping is clogged (Exhaust gas is mixed in intake
air during acceleration and deceleration)
Confirm recent repair history
Degree of use of
Operated for long period
machine
Suddenly became black
Color of exhaust gas Gradually became black
Blue under light load
Non-specified fuel is being used
Oil must be added more frequently
Suddenly
Power was lost
Gradually
Dust indicator is red (if indicator is installed)
Muffler is crushed
Air leaks between turbocharger and cylinder head, clamp is loosened
Engine is operated in low-temperature mode at normal temperature
When exhaust manifold is touched immediately after starting engine, temperature of
some cylinders is low
When engine is cranked, interference sound is generated around turbocharger
When engine is cranked, abnormal sound is generated around cylinder head
Torque converter stall speed or pump relief speed is high (Fuel is injected excessively)
Exhaust noise is abnormal
Engine does not pick up smoothly and combustion is irregular
Blow-by gas is excessive
If spill hose from injector is disconnected, abnormally much fuel spills
Inspect air cleaner directly
When turbocharger is rotated by hand, it is found to be heavy
Carry out troubleshooting for "EGR Valve Servo Error. (*1)". See *1 for failure code
Check EGR gas pressure piping directly (*2)
When compression pressure is measured, it is found to be low
Inspect valve clearance directly
When muffler is removed, exhaust color improves
Carry out troubleshooting for "Rail Press (Very) Low Error. (*3)" See *3 for failure code
When a cylinder is cut out for reduced cylinder mode operation, engine speed does
not change
Inspect fuel spill piping (on cylinder head side) directly
Carry out troubleshooting for "Coolant Temp Sens High (Low) Error. (*4)"
See *4 for code
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Remedy
40 Troubleshooting
Causes
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PC800, 850-8