What is a Car's Water Pump & What Does It Do

What is a Car's Water Pump & What Does It Do


For the cooling system to cool down the heat produced by the engine as best as possible, the coolant must circulate through the system. The water pump must circulate the coolant and maintain the continuity of this circulation necessary for heat exchange. The water pump assists the engine in the heating and cooling system quickly reaches and maintains the optimum operating temperature and prevents overheating.

In modern cars, mechanical or electrically driven water pumps are used, depending on the engine concept. Mechanical water pumps are integrated on top of a toothed belt drive or V-ribbed belt drive. The constant transmission ratio between the crankshaft and the water pump gear establishes a correlated link between the rotational speed of the crankshaft (i.e., engine speed) and the rotational speed of the water pump. Electrically driven water pumps operate independently of engine speed.

The performances of the water pumps can be adapted to the cooling requirements. This means that the ideal operating temperature can be reached more quickly. Because they are more efficient, electric water pumps also help reduce fuel consumption.


When replacing a faulty water pump, the gasket and the entire belt drive must always be replaced together to prevent the system from failing again (or even damage that could render the engine completely unusable) after a short time.


The water pump is maintenance-free. It is designed for the entire service life of the vehicle. However, the water pump can fail because of high stress and tension, incorrect belt tension, or damage to the belt drive. As part of routine maintenance and service work, regular inspection of the entire heating and cooling system provides the opportunity to detect and correct associated damage, leaks, and excessive wear at an early stage.

Water pumps integrated into toothed belt drives must be replaced at the same time as the toothed belt. This is because the gear wheel of the water pump wears out like a toothed belt. A worn water pump sprocket can cause premature damage to the belt drive, causing premature timing belt wear.