TM 5-3805-261-34
COOLING SYSTEM TROUBLESHOOTING AND MAINTENANCE PROCEDURES. (cont)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
ENGINE OVERHEATS. (cont)
Step 3.
Check the coolant flow from open drain outlet.
If coolant is dirty and the flow is slow, replace radiator. Refer to TM 5-3805-261-20.
NOTE
For the following procedures to be accurate, the engine should be at operating temperature and the ambient
temperature should be similar to field conditions.
Step 4.
Check the temperature at the top of the radiator tank with a probe from the Thermistor
Thermometer Group. Insert probe into the top of tank.
Compare temperature reading at the top of the radiator tank with the ambient temperature (air
temperature away from machine, not in direct sunlight).
If the difference between the top of the tank temperature and the ambient temperature is more than
110 degrees F, the engine is overheating. Proceed to step 6.
Step 5.
Check the coolant temperature at the bottom of the radiator tank with a probe from the Thermistor
Thermometer Group. Insert probe in the drain outlet of the radiator or in pipe plug location in the
lower elbow of radiator.
Compare coolant temperature reading at the top of radiator tank with coolant temperature reading
at the bottom of radiator tank.
If the difference between the top and bottom temperatures is more than 15 degrees F, proceed to step
6.
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