Mechanics

Water Pump Failure and Overheating

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Water Pump Failure

Engine coolant is used to transfer heat from the engine to the radiator by the cooling system. The radiator removes heat from the coolant by forcing air through the radiator fins. Without coolant your engine will overheat and severe engine damage will occur. The water pump is driven by a belt and powered by the engine which circulates coolant when the engine is running. This pump utilizes a veined impeller to pull the coolant from the block to the radiator.  Some BMW, Volkswagen and Audi cars have a common problem that the water pump impeller becomes dislodged from the input shaft of the water pump leaving the water pump looking ok from the outside, but failed on the inside. If your car experiences this problem it will over heat rapidly much like a thermostat failure.

Failed BMW, VW, Audi Water Pump
Failed Water Pump

Troubleshooting Procedure

Check Water Pump Operation - To troubleshoot this problem first drain about a half a gallon out of the cooling system, next remove the thermostat from the engine. With the thermostat out start the engine (stand back) coolant should be forced out of the thermostat port, if not the impeller has dislodged itself from the water pump input shaft and needs to be replaced. To replace the water pump finish draining the remainder of engine coolant, remove the serpentine belt and coolant hoses. Next remove the water pump mounting bolts and remove the water pump. Clean gasket surfaces and reinstall new water pump and reassemble. Refill with coolant and recheck system, top off engine coolant after it has re-cooled.

If further assistance is needed, our certified car repair technicians are ready to answer your car questions. Also, gain manufacturer specific instructions and information by clicking - Auto Repair Manual

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)