Abnormal Noise Is Made - Komatsu Galeo PC800-8 Shop Manual

40 Troubleshooting
S-15 Abnormal noise is made
General causes why abnormal noise is made
• Abnormality due to defective parts
• Abnormal combustion
• Air sucked in from intake system
aJudge if the noise is an internal noise or an external noise before starting
troubleshooting.
aThe engine is operated in the low-temperature mode while it is not warmed
up sufficiently. Accordingly, the engine sound becomes a little larger. This
does not indicate abnormality, however.
aWhen the engine is accelerated, it is operated in the acceleration mode
and its sound becomes a little larger for up to about 5 seconds. This does
not indicate abnormality, however.
Confirm recent repair history
Degree of use of
Operated for long period
machine
Gradually occurred
Condition of
abnormal noise
Sudden occurred
Non-specified fuel is being used
Oil must be added more frequently
Metal particles are found when oil filter is drained
Air leaks between turbocharger and cylinder head
When engine is cranked, interference sound is generated around turbocharger
When engine is cranked, abnormal sound is generated around EGR gas piping
When engine is cranked, abnormal sound is generated around cylinder head
When engine is cranked, beat noise is generated around muffler
When exhaust manifold is touched immediately after starting engine, temperature
of some cylinders is low
Blue under light load
Color of exhaust
gas
Black
Engine does not pick up smoothly and combustion is irregular
Abnormal noise is loud when engine is accelerated
Blow-by gas is excessive
When turbocharger is rotated by hand, it is fount to be heavy
Inspect EGR gas piping directly
Inspect dynamic valve system directly
When muffler is removed, abnormal noise disappears
Inspect valve clearance directly
When compression pressure is measured, it is found to be low
Inspect gear train directly
Inspect fan and fan belt directly
When a cylinder is cut out for reduced cylinder mode operation, engine speed
does not change
Abnormal noise is heard only when engine is started
Check with monitoring function of the machine monitor
PC800, 850-8
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Remedy
SEN00795-02
Causes
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