Komatsu PC200-8M0, Shop Manual, Page: 944 / 1254

600 Troubleshooting of engine (S-mode)
S-15 Unusual noise is made
40-600
22
PC200, 200LC, 220, 220LC-8M0
SEN06140-00
S-15 Unusual noise is made
General causes why unusual noise is heard
q
Abnormality due to defective parts
q
Abnormal combustion
q
Air sucked in from air intake system
a
Judge if the noise is an internal noise or an external noise before starting troubleshoot-
ing.
a
The engine is operated in the low-temperature mode while it is not warmed up suffi-
ciently. Accordingly, the engine sound becomes a little larger. This does not indicate
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 three seconds. This does not indicate abnormal-
ity, however.
Cause
Air leak a
t tubin
g between
turbocharg
e and cylin
der head
Seizur
e or inter
ference at tur
bocharger
Dama
ge of valve system (
v
alve
or r
ocker lever)
Defe
ctive
inside of muf
fler
(p
a
rtition b
oard out
of position)
Impr
oper valve clearance
Excessively wo
rn piston
ring or cylinder
Impr
oper ge
ar tra
in ba
cklash
Dislocated or
seized bushin
g
Defo
rmed cooling fa
n, loo
s
e fan
belt,
inter
ference of fa
n belt
Clogged o
r seized inje
ctor
Dirt caught
in inje
ctor
Impr
oper fu
el inje
ction timing
(d
efect
in low coolant temper
ature
sensor or
boost temper
ature sensor)
Qu
estions
Check recent repair history.
Machine opera-
tion hours
Operated for long period
E
Abnormal noise
Gradually occurred.
Q Q
Sudden occurred.
Q Q Q
Fuel other than specified one is used
Q
Engine oil must be added more frequently.
w
Metal particles are found in the removed oil filter.
w w
Air leaks at tubing between turbocharger and cylinder head.
w
C
heck items
While engine is running, interference sound is heard from turbocharger.
w
While engine is running, unusual noise is heard around cylinder head.
w w
While engine is running, beat noise is heard around muffler.
w
When exhaust manifold is touched immediately after starting engine, temperature of
some cylinders is low.
w Q
Color of exhaust
smoke:
Blue under light load
w
Black
Q w Q
Engine does not pick up smoothly and combustion is irregular.
w
Unusual noise is loud when engine is accelerated
Q Q Q Q
Blowby gas is excessive
w
T
roubleshooting
When turbocharger is rotated by hand, it is found to be heavy.
q
Check valve system.
q
If muffler is removed, unusual noise disappears.
q
Check valve clearance.
q
When compression pressure measured, it is found to be low.
q
Check gear train.
q q
Check fan and fan belt.
q
Even if a cylinder is cut out, engine speed does not change.
q q
Unusual noise is heard only when engine is cranked.
q
Check the condition by using monitoring function of machine monitor.
q
Remedy
Replace Replace Replace Replace
Adj
u
s
t
Replace Replace Replace
Rep
a
ir
Replace Replace Replace