THEORY OF OPERATION Continued
The M548A1 and M548A3 cooling system consists of a radiator, engine coolant pump, thermostat, engine, transmission and
differential (M548A1) oil cooler, and connecting hoses and clamps. A fan assembly provides fresh air for the engine air
intake and power plant cooling systems. The fan drive belt set connects the power from the fan drive shaft (M548A1) to the
fan assembly. The belt set is a matched set. If one or more belts are bad, the whole set needs to be replaced.
The fan and radiator are mounted on the right side of the power plant compartment. The engine coolant pump, thermostat,
and oil cooler are integral components of the engine assembly. The coolant filler cap is where the engine coolant is filled.
Coolant is drawn by the pump from the bottom of the radiator and circulated through the oil cooler, cylinder block, and
cylinder heads to the thermostat housing and back to top of radiator. The thermostat is a full bypass-type with a range of 161
C) for the M548A1 and 181
C) for the M548A3. The deaeration elbow helps to remove
air from the coolant system.