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Coolant flow

Coolant flow

The coolant always circulates in the oil cooler as well as in the heat exchanger circuit regardless of the thermostat position.

Thermostat closed


From the coolant pump - through channels in the cylinder block - up through the cylinder head - to the thermostat housing - returns to the pump (internal circulation).

A certain portion of the flow exits the cylinder block - through a hose to the oil cooler and through the EGR valve - and on through a hose via the lower inlet on the thermostat housing to the pump.

The heat exchanger flow exits from the rear of the cylinder head - through a hose to the auxiliary heater - continues through a hose to the heat exchanger - through a return hose from the heat exchanger - and returns to the pump.

With the thermostat normally open


From the coolant pump - through channels in the cylinder block - up through the cylinder head - through the thermostat housing upper outlet (past the thermostat) - through the radiator - and returns through the lower inlet on the thermostat housing to the pump.

A certain portion of the flow exits the cylinder block - through a hose to the oil cooler and through the EGR valve - and on through a hose via the lower inlet on the thermostat housing to the pump.

The heat exchanger flow exits from the rear of the cylinder head - through a hose to the auxiliary heater - continues through a hose to the heat exchanger - through a return hose from the heat exchanger - and returns to the pump.

With the thermostat fully open

The thermostat closes internal circulation in the engine, and the majority of the coolant then passes the radiator. The rest of the coolant passes the oil cooler as well as the heat exchanger.