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What Does an Electric Water Pump Do?

An electric water pump, or EWP, is a mechanical device, powered by electricity, that pumps water through the cooling system of your car.

Because it relies on electricity, an EWP will work as long as there is power in the battery. This means that if a vehicle has been running for a while and the ignition gets switched off, a control device can keep the EWP running afterwards. This is especially crucial in automotive high load areas or in motorsport.

On the other hand, a mechanical water pump stops working when the engine is turned off and the battery is no longer operating.

This means cooling fluid is no longer pushed through the engine internals and through the radiator, which can lead to severe damage to the engine and potentially the radiator as well.

Another benefit of an EWP is the constant pressure and flow rate, including the ability to consistently deliver flow since they’re not dependent on a crankshaft and belt to spin.

What’s more, because an EWP is electrically powered, they’re not sapping energy from a mechanical system.

This means less strain, better fuel economy, and longer lasting mechanical parts. They’re also a lot smaller, which means less weight, better efficiency, and they can be mounted in certain positions to help tidy up an engine bay.

In contrast, it is quite common to find systems where a mechanically driven fan is attached to the nose of a mechanically driven water pump.

The fan has a kind of clutch that allows the fan to spin up to speed or spin down to a stop by itself. In a cooling sense, these fans are only effective if the engine is running.

Due to their source of power, these types of fans will not be as energy or fuel efficient, plus they’ll sometimes not be as aerodynamically efficient due to the design of the fan blade, or their location in respect to the radiator.