Komatsu Galeo PC138US-8, Shop Manual

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40 Troubleshooting SEN02469-01
PC138US, USLC-8
21
S-12 Oil pressure drops 1
General causes why oil pressure drops
q
Leakage, clogging, wear or lubrication system
q
Defective oil pressure control
q
Improper selection of fuel (improper viscosity)
q
Deterioration of oil due to overheating
Causes
W
o
rn journal of
bearing
Lac
k of
oil
in
oil p
a
n
Coolant
, f
uel in o
il
Cl
og
ged s
trainer
in oil p
a
n
Cl
og
ged,
broken pipe
in oil
p
a
n
Def
e
ct
ive oil
pum
p
Def
e
ct
iv
e regulat
o
r
va
lv
e
Cl
og
ged oil f
ilt
er
Leaking,
crus
hed,
clogged hydrau
lic piping
Def
e
ct
iv
e oil
lev
e
l s
e
ns
or
, wiring
har
n
es
s
Qu
e
st
io
n
s
Confirm recent repair history
Degree of use of machine Operated for long period
E E E
Oil pressure monitor indicates low oil pressure
Q w
Non-specified oil is being used
Q Q
Replacement of filters has not been carried out according to Operation and Maintenance
Manual
w
Oil pressure monitor
(if installed)
Indicates pressure drop at low idle
w
Indicates pressure drop at low, high idle
Q w w w Q
Indicates pressure drop on slopes
w
Sometimes indicates pressure drop
w Q
Oil level monitor indicates oil level drop
w w
Oil level in oil pan is low
w
Ch
ec
k it
em
s External hydraulic piping is leaking, crushed
w
Oil is milky or smells of diesel oil
w
Metal particles are found when oil pan is drained
w
Metal particles are found when oil filter is drained
w Q
T
roub
le
shoot
ing
Metal particles are found in oil filter
q
See S-13
Inspect oil pan strainer, pipe directly
q q
Oil pump rotation is heavy, there is play in oil pump
q
Valve and spring of regulator valve are fatigued, damaged
q
Inspect oil filter directly
q
If oil level sensor is replaced, oil level monitor indicates normally
q
Remedy
Replac
e
Ad
d
—
Clean Clean
Replac
e
Replac
e
Replac
e
Cor
rec
t
Replac
e