How Does a Car Water Pump Work?

by John Albers
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What is a Car Water Pump?

A water pump is a belt driven device found in any car which transfers water from the radiator to the engine, thereby helping to keep it cool. The outward design of the water pump can change from one car to another, but there are some basic similarities as a result of their identical function. The water pump can be found near the car's front or side, behind the fan belt. It will look a bit like an octopus, with a prominent hollow disc shape in the center and several arms radiating outward. One arm should be attached to the radiator; another should be attached to the engine. These are hollow pipes in reality, where the other arms are simply for added support to keep the water pump in place. Rising from the disc should be an axle, over which is either the fan belt or a secondary adjacent belt.

How Does a Car Water Pump Work?

As the car engine runs, the fan belt turns, turning the axle at the center of the water pump. The pump operates on centrifugal force. In the center hollow of the pump is the axle on the inside of the pump, connected to a series of vanes, which turn along with the axle. This turning motion creates suction, pulling water from the radiator. The water reaches the pump and is thrown against the exterior walls of the pump by the power of the vanes which are generating the centrifugal force. As the water circles against the outer wall, it presses down a drain, which sends the water into the engine block. From there it passes into the cylinder heads, and drains back into the radiator for the process to repeat itself.

How to Tell if Your Water Pump is about to Fail.

Every water pump has something called a weep hole. The hole is just a few millimeters in diameter and should be located on the side of the pump or facing toward the ground. Normally the weep hole is sealed by a gasket, but as the water pump begins to wear, the gasket will erode. As a result coolant will begin to dribble out of the hole. This is very serious and indicative that the water pump is no longer able to do its job. If coolant should leak out of this hole while the engine is idling, you're best course of action is to head to the closest mechanic immediately. You risk overheating your engine and doing irreparable damage to it otherwise.

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