Abnormal Noise Is Made - Komatsu Galeo PC138US-8 Shop Manual

SEN02469-01
S-15 Abnormal noise is made
General causes why abnormal noise is made
Abnormality due to defective parts
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Abnormal combustion
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Air sucked in from intake system
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a Judge if the noise is an internal noise or an external
noise before starting troubleshooting.
a The 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 indi-
cate abnormality, however.
a When the engine is accelerated, it is operated in the
acceleration mode and its sound becomes a little larger
for up to about 3 seconds. This does not indicate abnor-
mality, however.
Confirm recent repair history
Degree of use of machine
Condition of abnormal noise
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 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
Color of exhaust gas is
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 found to be heavy
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
Confirm with monitoring function
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Operated for long period
Gradually occurred
Suddenly occurred
Blue under light load
Black
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Remedy
40 Troubleshooting
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Causes
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PC138US, USLC-8