1. Clean the cooling system with a good cooling system cleaner and thoroughly flush to remove scale deposits.
Clean the exterior of the radiator core to open plugged passages and permit normal air flow. Adjust fan belts to
the proper tension to prevent slippage. Check for an improper size radiator or inadequate shrouding. Repair or
replace inoperative tempera- ture-controlled fan or inoperative shutters.
2. Check the coolant level and fill to the filler neck if the coolant level is low. Inspect for collapsed or
disintegrated hoses. Replace faulty hoses. Thermostat may be inoperative. Remove, inspect, and test the
thermostat; replace if found faulty. Check the water pump for a loose or damaged impeller. Check the flow of
coolant through the radiator. A clogged radiator will cause an inadequate supply of coolant on the suction side
of the pump. Clean the radiator core. Remove the coolant filler cap and operate the engine, checking for
combustion gases in the cooling system. The cylinder head must be removed and inspected for cracks and the
head gaskets re- placed if combustion gases are entering the cooling system. Check for an air leak on the
suction side of the water pump. Replace defective parts.
3. The thermostat may not be closing. Remove, inspect and test the thermostat. Install a new thermostat, if
Check for an improperly installed heater.
4. Excessive leakage of coolant past the thermostat seal(s) is a cause of continued low coolant operating
temperature. When this occurs, replace the thermostat seal(s).