The water pump is mounted on the front of the engine and is connected to the fan, if your car has a mechanical fan. In any case, it runs off a drive belt connected to the crank pulley. Identify the belt and check it for proper tension and cracks. If the belt is too loose, tighten it by adjusting either the alternator, which usually tightens the fan belt, or the idler pulley. Inspect the front of the water pump for leaks of coolant, which is green, or engine oil. Grab the fan and wobble it, or attempt to wobble it. If there is play from front to back in the fan, the water pump bearing may be going out. If the bearing screeches when the engine is running and the fan belt is tight, the bearing is probably shot.

Water pumps are simple devices. There is a shaft on which the fan mounts. The shaft drives an impeller, which is inside the coolant passages of the engine. There is an oil passage to the bearing which lubricates it. When the bearing goes bad, the coolant will leak out through the worn out bearing and will drip down the front of the engine. In some cases the impeller will slip on the shaft and the water pump will no longer pump, even though the bearing does not leak. When this happens the engine will overheat. Change the thermostat to rule out a broken thermostat if the engine is overheating, then suspect the water pump. Of course, you must have coolant in the engine, so check the radiator for full when the engine is cold.

Almost every failed water pump will be the result of a bad bearing. You can hear the bearing squeal when the engine is running, usually. If the belt is tight it is probably a bearing. Listen around to determine that it is not an alternator, power steering pump, or AC bearing that has gone bad. If you see anything leaking out of the water pump housing, it will have to be changed.

A water pump is not usually an expensive item. Rebuilt units should cost from 25 to 50 dollars, depending on the make and model. Import prices may be a bit higher. Be sure to get a gasket, and use permatex on it when you change out the water pump. Clean all old gasket material and sealant off the block with a putty knife. Tighten bolts to the proper torque in sequence when bolting on the new pump. Fill radiator with coolant and mount the fan and tension the belt. A water pump is not a hard deal to replace.

Learn more about this author, William Remski.
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