Checking the operation of the water pump (BMW 5 Series E28)

A failed water pump can cause serious engine damage due to overheating.

There are two ways to check the water pump without removing it from the engine. If one of them results in the pump being faulty, it should be replaced with a new one.

Water pumps are usually equipped with vent holes. If the pump seal is damaged, fluid will leak from this hole. In most cases, you will need to use a flashlight to locate this hole on the underside of the pump to check for signs of a leak.

A faulty water pump bearing is usually indicated by a creaking sound from the front of the engine while it is running. A worn pump shaft is indicated by the pulley bouncing up and down (with the drive belt removed). Don't confuse the squealing noise of a slipping drive belt with the squealing noise of worn pump bearings. Worn alternator bearings can also cause a squealing noise, but once the drive belts are removed, it's fairly easy to tell the difference.