Water Pump Replacement

The water pump plays one role in the coolant system and that role is to provide circulation to the coolant. Water pumps provide circulation by the use of an impellers, which is driven by a belt, so the impeller can propel the coolant through the system.

Water pumps can be either externally mounted or internally mounted, depending on the vehicle.

EXTERNAL WATER PUMPS are driven by the drive belts. The drive belts are the belts that are visible when the hood is open and these belts play the role of operating the accessories--such as the alternator, power steering, air conditioning and of course the water pump. External water pumps may have their own belt or they may share the same belt as the other accessories.

INTERNAL WATER PUMPS can be either driven by the timing belt or the timing chain. Timing belts and timing chains are not visible when the hood is propped open. One of these connects and synchronizes the water pump to the crankshaft and the camshaft or camshafts, depending whether it is a dual over-head cam engine or a single cam engine. When changing a timing belt or a timing chain driven water pump, it may take extra time and greater concentration, because lining up the timing marks on both the crank and camshafts has to be precise or the engine will run rough or not at all. This could damage the engine.

Water pumps can fail to circulate the coolant properly due to one of three possibilities: they may leak, the impeller blade or its bearings may become worn or the belt may be loose or broken. All water pumps have small leak holes on the bottom of the water pump housing. These are designed to leak coolant when the impeller bearing fails. Allowing coolant to leak externally through the leak hole provides advanced notice of an issue with the water pump, before the bearing seizes up, the pulley the belt rides on falls off or the impeller falls off inside the engine—potentially resulting in catastrophic engine failure.

Having knowledge of how the engine operates will provide a better understanding of how the timing belt or timing chains can be removed and reinstalled. The following steps will provide a better understanding of how to change an externally mounted water pump--keeping in mind that internally mounted water pumps basically require the same procedure minus the additional knowledge needed to remove and reinstall a timing belt or timing chain. If your vehicle is equipped with a timing belt or timing chain, click here to view the timing belt/chain page of our website.