Early automobile engines did not have an important accessory that we consider essential today – a water pump. The liquid cooling medium used at that time was pure water, mixed with at most a little wood alcohol to prevent freezing. The circulation of cooling water relies entirely on the natural phenomenon of thermal convection.

After the cooling water absorbs heat from the cylinder block, it naturally flows upward and enters the upper part of the radiator; after the cooling water becomes cold, it naturally sinks to the bottom of the radiator and enters the lower part of the cylinder block. Using this thermosiphon principle, the cooling task can be barely completed. But soon, water pumps were added to the cooling system to move the cooling water faster.

The cooling system of modern automobile engines generally uses centrifugal water pumps. The reasonable installation location of the water pump is at the bottom of the cooling system, but most water pumps are placed in the middle of the cooling system, and a few water pumps are placed on the top of the engine. Water pumps placed on top of the engine are prone to cavitation.

The cooling system of modern automobile engines generally uses centrifugal water pumps. The reasonable installation location of the water pump is at the bottom of the cooling system, but most water pumps are placed in the middle of the cooling system, and a few water pumps are placed on the top of the engine. Water pumps placed on top of the engine are prone to cavitation.