CarCare

The stereotypical water pump has a fan attached to its snout. The engine's accessory-belt system spins a pulley, which in turn rotates the pump's impeller to circulate coolant through the engine.


Another style of water pump doesn't use a belt to spin its impeller. This type uses the timing gear or other direct-drive system. In other words, the water pump has a shaft that's driven directly by the engine, similar to how power transfers from the engine to the transmission.


While both pump styles are effective at circulating coolant throughout the engine, each has its pros and cons. Obviously, belts have limited service lives, so it's only a matter of time until they fail. However, belts are usually fairly easy to access, diagnose and replace. Another plus: Belt-driven water pumps are also usually relatively easy to remove and replace.


Belt-less pumps have fewer parts (no pulley or belt), so they theoretically last longer. The drawback is that these water pumps can be obscured, causing the average do-it-yourselfer to curse the automotive engineer who obviously never had to service his or her design. Replacing these pumps is generally more time-consuming than with belt-driven ones: Numerous other components and system may have to be removed to gain access to the pump.

Pump Problems
In general, one of two things usually causes water-pump failure. The first is when the pump's shaft's bearings wear out. Squealing and whining usually foreshadow the bearings' ultimate demise. The other scenario is seal failure. This causes coolant to leak from the pump's "weep" hole. Coolant drips that can't be traced to the radiator hoses, overflow tanks or the thermostat housing often originate at the water pump's gaskets.

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Photo Guide

Replacement water pumps normally come complete with the necessary gaskets. (This one has four possible leak zones.)

On this car, the water pump is inconveniently concealed beneath the exhaust manifold. Consult a service manual about any parts that need to be removed to gain access to the water pump.

Following the service manual, continue to work toward freeing the water pump. Here, the radiator outlet pipe is unfastened before being dislodged from the pump housing.

For this job, the water pump housing is unbolted from the engine block, then from the pump itself.

Removing the pump housing gives access to the three studs and nuts that secure this water pump to the timing-chain housing.

Scrape off old gasket material from all surfaces. Then, use lacquer thinner or acetone and elbow grease to remove any adhesive residue. Also clean all threads and bolt holes.

Use gasket sealer and/or RTV silicone as specified in the service manual and/or instructions that come with the replacement water-pump kit.

Here, we cleaned old gasket debris from inside the timing-chain housing, then lubed the female splines that receive the pump's shaft with chassis grease per the service manual's instructions.

Install the replacement pump. Refer to the service manual for proper fastener re-fastening sequence and specified bolt torque. Then, reverse the remaining disassembly procedure. Fill the system with the appropriate antifreeze dilution and test for leaks.



Related Articles
Radiator Leak Repair
Electric Cooling Fan Install
Blower Fan Repair
Cooling System Flush
Water Pump Replacement


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