To effectively dissipate the heat generated by the engine, a radiator and fan is used. A centrifugal-type water
pump is used to circulate the engine coolant in the system. It incorporates thermostats to maintain a normal
operating temperature of 160-185 (71-850C). The engine coolant is drawn from the lower portion of the
radiator by the water pump and is forced through the oil cooler and into the cylinder block.
From the cylinder block, the coolant passes up through the cylinder head(s) and, when the engine is at normal
operating temperature, through the thermostat housing(s) and into the upper portion of the radiator. Then the
coolant passes down a series of tubes where the coolant temperature is lowered by the air stream created by
the revolving fan.
Upon starting a cold engine or when the coolant is below operating temperature, the coolant is restricted at the
thermostat housing and a bypass provides water circulation within the engine during the warm-up period.
Figure 1. Typical Cooling System for an In-Line Engine