TM 5-4320-300-14
Table 4-2. Organizational Maintenance Troubleshooting - Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
WARNING
Hot coolant may be released when radiator
cap is removed. Allow engine to cool before
removing cap. Open cap part way to ensure
that pressure in cooling system is released,
then remove cap.
a. Remove and test the thermostat. Remove radiator cap and open draincock at bottom right of
radiator. Drain the cooling system to a level where the coolant is below the thermostat.
Disconnect the radiator hose at water outlet elbow after loosening clamp. Remove bolts,
lockwashers, water outlet elbow, gasket, and thermostat. Check the operation of the
thermostat by immersing it in a container of hot water. Place a thermometer in the container,
but do not allow it to touch the bottom. Agitate the water to maintain an even temperature
throughout the container. As the water is heated, the thermostat should begin to open when
the temperature reaches 167-172°F (75-78°C). The opening temperature is stamped on the
thermostat.-The thermostat should be fully open at approximately 190-192°F (88-89°C).
If thermostat is faulty, replace it. Remove any old gasket from gasket surface of thermostat
housing and the water outlet elbow. Install new gasket and position water outlet elbow. Install
mounting bolts and lockwashers. Tighten bolts to 23-26 ft-lbs (31-35 N•m). Position upper
radiator hose on water outlet elbow and tighten hose clamp snugly. Pour collected coolant
back into radiator and install radiator cap. Start engine and check for leaks. If leaks appear,
tighten hose clamp on water outlet elbow.
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