How do water pumps work

The water pump - the heart of the engine cooling system

What does the water pump do?

All combustion engines are equipped with a cooling system by the car manufacturer. An important part of the cooling system is the water pump. As soon as the engine is running, the water pump also runs. It transports the coolant to the radiator and from there back to the cylinder walls.

Water cooling is better than air

Current cars are all water-cooled. The advantages over a car cooled by an air blower - for example the Volkswagen Beetle or the Porsche 993 - predominate. On the plus side, the water cooling system has a functioning interior heating system, lower engine noise and a balanced heat balance. In addition, a water-cooled engine reaches its operating temperature much more quickly. This saves fuel, lowers pollutant emissions and reduces engine wear.

Advanced technology - more sources of error

Of course, a liquid-cooled engine has a few more parts that can break than a simple air-cooled machine. The cooling system consists of the radiator, the hoses, the expansion tank and the water pump. The latter keeps the coolant, a mixture of water and antifreeze, in constant motion. Hot liquid is pumped from the engine to the radiator, where it cools, then transported back to the engine, where it heats up, and so on. The whole system will not work without a water pump.

What does the pump do?

The water pump ensures the circulation of the coolant in a vehicle. In this way, the pump ensures that the motor quickly reaches its optimum operating temperature and that it is protected from overheating. An antifreeze is added to the liquid. In this way, the entire cooling system - including the engine - can function properly when the outside temperature is below freezing.

Why does the engine need to be cooled?

When a car is set in motion, gases are ignited in the combustion chamber of the engine block and thus high temperatures are generated. The excess heat must be absorbed. If the engine were not continuously supplied with liquid, the seals and other materials would be severely damaged by the heat. Further operation of the vehicle would no longer be possible within a very short time.

The pump keeps the water constantly in motion and in this way ensures that the liquid used does not have to absorb too much heat. In this way, the pump prevents the coolant from evaporating or from being unable to cool down. In both cases, no further cooling could take place.

What types of coolant pumps are there?

Depending on the type of engine, mechanical and electrical coolant pumps are used in modern cars.

Mechanical pumps

The mechanical pumps are integrated into the toothed belt drive and controlled by it. This means that their speed is linked to the engine speed. The water pump and toothed belt are not only related to the drive. The water pump is often changed when the belt is replaced.

Electric pumps

The electric coolant pumps are driven independently of the engine. Your performance can thus be adapted exactly to the respective needs.

The result is:

  • the optimal operating temperature of the engine is reached more quickly
  • the fuel consumption is reduced by the better efficiency

The difference to the auxiliary water pump

The auxiliary water pump has only been used as standard in modern vehicles since 2000. The task of the additional water pump is to supply the built-in heater with hot water.

Furthermore, the additional water pump ensures that - after the engine has been switched off - no build-up heat builds up in the cylinder head. To achieve this, the pump will continue to run for about two to three minutes after the engine has been switched off.