General information about the cooling system (Mercedes-Benz E-Class W124)

The sealed cooling system includes a water pump driven by an auxiliary drive belt, a radiator fan with a thermoviscous or electromagnetic clutch, a cross-flow or downflow radiator, an expansion tank and overflow tank, a thermostat and heater core, and hoses and switches. When a cold engine is started, coolant circulates around the cylinder block and cylinder head. Warm coolant passes through the heater fan to the water pump. As the coolant expands when heated, its level in the expansion tank rises. The coolant flow through the radiator is closed, which ensures a closed thermostat. When the coolant reaches a predetermined temperature, the thermostat opens and the hot coolant passes through a hose to the radiator. As the coolant passes through the radiator, it is cooled by the oncoming air flow. The thermoviscous clutch of the radiator fan is activated depending on the air temperature behind the radiator. When a predetermined temperature is reached, the valve in the clutch opens and the thermoviscous clutch activates the radiator fan impeller. When the temperature decreases, the thermoviscous clutch reduces the torque transmission and the rotation of the radiator fan slows down. The electromagnetic clutch of the radiator fan is activated by a temperature sensor installed in the cooling system. When the clutch is activated, its clutch is engaged and the radiator fan begins to rotate from the auxiliary drive belt. When the coolant temperature decreases below a predetermined value, the electromagnetic clutch is disengaged, as a result of which the radiator fan impeller rotates freely. When the expansion tank overflows, the coolant is directed to the overflow tank, which is installed on the inner arch of the right wheel.

On some models, the coolant also passes through an engine oil heat exchanger located under the oil filter housing.

To ventilate the car's interior, air is supplied through a grille in the rear of the engine compartment. If necessary, the air flow can be increased using the heater fan. Air is removed from the interior through ducts in the rear of the car. To heat the air entering the car's interior, air is passed through the heater radiator.

Warning! When opening the expansion tank cap on a hot engine, be careful, as the escaping steam can cause severe burns. To do this, cover the expansion tank cap with a thick layer of cloth and slowly unscrew the cap until a hissing sound is heard. After the hissing stops, slowly unscrew and remove the cap from the expansion tank.