Coolant Temperature Becomes Too High (Overheating) - Komatsu ecot3 PC300LC-8 Shop Manual

40 Troubleshooting
S-14 Coolant temperature becomes too high (overheating)
General causes why coolant temperature becomes too high
• Lack of cooling air (deformation, damage of fan)
• Drop in heat dissipation efficiency
• Problem in coolant circulation system
Confirm recent repair history
Degree of use of
Operated for long period
machine
Sudden overheated
Condition of
overheating
Always tends to overheat
Coolant tempera- Rises quickly
ture gauge
Does not go down from red range
(if installed)
Radiator coolant level monitor indicates drop of coolant level (if monitor is installed)
Engine oil level has risen and oil is milky
Fan belt tension is low
When fan belt is turned, it has play
Milky oil is floating on coolant
There are excessive air bubbles in radiator, coolant spurts back
When light bulb is held behind radiator core, no light passes through
Radiator shroud, inside of underguard are clogged with dirt or mud
Coolant is leaking because of cracks in hose or loose clamps
Coolant flows out from radiator overflow hose
Fan belt whines under sudden acceleration
Hydraulic oil temperature gauge indicates red range faster than engine coolant tem-
perature gauge does (if they are installed)
When compression pressure is measured, it is found to be low
Inspect cylinder liner directly
Inspect oil cooler directly
Temperature difference between upper and lower tanks of radiator is large
When operation test of thermostat is carried out, it does not open at cracking tem-
perature
Temperature difference between upper and lower tanks of radiator is slight
Inspect radiator core directly
When operation of radiator cap is carried out, its cracking pressure is low
Inspect fan belt, pulley directly
When coolant temperature is measured, it is fount to be normal
PC300, 350-8
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Remedy
SEN02634-02
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Cause
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