Komatsu BR380JG-1E0, Shop Manual, Page: 784 / 841

40 Troubleshooting SEN02307-00
BR380JG-1E0
21
S-14 Coolant temperature becomes too high (overheating) 1
General causes why coolant temperature becomes too
high
q
Lack of cooling air (deformation, damage of fan)
q
Drop in heat dissipation efficiency
q
Problem in coolant circulation system
q
Rise in hydraulic oil temperature
o
Carry out troubleshooting for machine
Causes
Broken cylin
der head
, head gasket
Holes caused by pitting Clogged, br
oken
oil cooler
Lack of
coolant
Broken wate
r pump
Defective op
eration of ther
most
at
Clogged, crushed r
adia
tor fins
Clogged r
adiato
r core
Defective r
adia
tor cap (pr
essur
e va
lve)
Defective fan
pulley bearing
Slipping fan belt, wor
n fan pulley
Defective coolant temper
ature g
auge
Rise of
hydr
aulic oil temper
at
ure
on applicable machine
side
Qu
estions
Confirm recent repair history
Degree of use of
machine
Operated for long period
E E E E
Condition of overheating
Sudden overheated
Q w Q
Always tends to overheat
Q w w Q
Coolant temperature
gauge (if installed)
Rises quickly
Q w
Does not go down from red range
w
Radiator coolant level monitor indicates drop of coolant level (if monitor is
installed)
w
Engine oil level has risen and oil is milky
w Q
Fan belt tension is low
w
C
heck items
When fan belt is turned, it has play
w
Milky oil is floating on coolant
w
There are excessive air bubbles in radiator, coolant spurts back
w
When light bulb is held behind radiator core, no light passes through
w
Radiator shroud, inside of underguard on applicable machine side are clogged
with dirt or mud
w w
Coolant is leaking because of cracks in hose or loose clamps
w
Coolant flows out from radiator overflow hose
w
Fan belt whines under sudden acceleration
w
Hydraulic oil temperature enters red range faster than engine coolant
temperature
w
T
roublesh
ooting
When compression pressure is measured, it is found to be low
q
Car
ry out tr
oubleshoo
ting
on applicable machine
side
Inspect cylinder bore directly
q
Inspect oil cooler directly
q
Temperature difference between upper and lower tanks of radiator is large
q
When operation of thermostat is carried out, it does not open at cracking
temperature
q
Temperature difference between upper and lower tanks of radiator is slight
q
Inspect radiator core directly
q
When operation of radiator cap is carried out, its cracking pressure is low
q
Inspect fan belt, pulley directly
q
When coolant temperature is measured, it is fount to be normal
q
Remedy
Replace Replace Replace Ad
d
Replace Replace Corr
ect
Corr
ect
Replace Replace Corr
ect
Replace
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