What is a water pump and where is it located?

One of the key components of the automotive cooling system is the engine water pump, also known as the coolant pump. It serves a crucial role in keeping your engine from overheating by circulating the coolant through the engine and radiator. The process of coolant circulation is what pulls heat away from the engine and allows it to maintain the correct proper operating temperature. In terms of location, automotive water pumps are usually mounted to the front of the engine, and often behind the timing cover.

The majority of vehicles have basic centrifugal (mechanical) water pumps consisting of a main shaft, housing, and impeller. Attached to the mechanical water pump’s main shaft is a pulley or gear, which can be driven by the rotation of the crankshaft by an accessory belt, timing belt, or chain depending on the application. On the other end of the main shaft lies the impeller; cooled coolant from the radiator enters near the center via an inlet and is forced outwards as it spins, circulating the coolant through the engine. From there, the coolant goes around the engine’s cylinders and, as it does, it picks up the heat from the friction and burning of fuel, thus transferring it from the engine to the coolant. The warm fluid is then forced out and travels through the upper radiator hose and into the automobile’s radiator via the water outlet. From there it goes into small chambers that are all throughout the radiator, where it is then cooled down by the air that is passed freely through the radiator’s core by the radiator fan. Air passes through the radiator when the vehicle is moving as well, but the use of cooling fans aids this process when the engine is being worked harder, and/or when the car or truck isn't moving. The cooled coolant then goes back to the water pump via the lower radiator hose and the process repeats itself. 

In addition the mechanical water pump, a few vehicles also have a secondary (or auxiliary) electric water pump to assist in the circulation process. Other forced induction automobiles that are equipped with a water-to-air intercooler also require the use of an electric water pump.

How do I know my water pump needs to be replaced?

Water pumps can last a fairly long time on vehicles with properly maintained coolant systems. Changing your car or truck’s coolant in regularly scheduled intervals will go a long way in preventing failure of any coolant system components. So how do you know if your water pump needs to be replaced? An early sign would be what is known as the “weep hole drip,” which refers to a small amount of coolant leaking from the water pump onto the ground. There are two very small passages on the water pump bearing housing—an upper and a lower—and these are known as weep holes. Normally, a seal prevents coolant from leaking through the lower hole; however, this seal can fail due to age or coolant contamination.  This type of leak is also a sign the main shaft bearings may be on their way to failure. If you have noticed signs of coolant leakage under your vehicle or a loss of coolant, it is time to inspect your car or truck’s water pump as this may be an indicator that it has failed.

Other possible auto water pump failures can be due to a cracked housing, broken impeller or main shaft. Failures of these matters may also directly or indirectly result in severe engine damage. These types of failures are often preceded by early warning signs such as a coolant leak or bearing noise, proving the importance of regular maintenance. If the water pump fails, the engine will overheat, causing it to shut down, which can possibly lead to more serious problems as well as cause considerable damage to the engine, so if you water pump is broken, it's important to fix it.

Can I replace the water pump myself?

As mentioned above, automotive water pumps are usually mounted to the front of the engine of a car or truck, and often behind the timing cover. For this reason, it is wise and cost effective to replace your water pump as preventative maintenance the same time you perform a timing belt or chain replacement. Performing a water pump replacement can be done by your average do-it-yourselfer on most vehicles, providing they have a good set of hand tools and basic mechanical ability. A chain wrench would be useful for this repair as well. The process may require the removal of the air intake or coolant reservoir in order the access the pulleys. Hold the water pump pulley with a chain wrench and remove the bolts keeping the pulley in place. Then remove the pulley itself. Next remove the bolts around the water pump and pull the water pump out. Reinstallation is just a reversal of the procedure with the extra step of reinstalling your serpentine belt. Be sure to follow the diagram while reinstalling. As always, a decent repair manual for your automobile will take you through the entire process.