Diagnosing water pump noises can be tricky.
Quite often your water pump is buried deep in the engine.
As a result, water pump noise will resonate throughout the engine, making it even harder to identify.
Given a chance, a failed water pump could overheat and completely destroy your engine. Although the water pumps in most modern cars, trucks, and SUVs will last a long time; they are by no means indestructible. Like any other mechanical device, they will produce a few warning signs of wearing out. Fortunately, things don’t have to get to that point.
So, How Does Your Water Pump Work
Your water pump has a simple but efficient design. The water pump uses an impeller; mounted on one end of a shaft, to push coolant throughout your:
- Engine block
- Cylinder heads
- Heater core
- Intake manifold
- And, all connecting hoses and lines
So, the shaft has a pulley on the other end and is supported by one or two bearings; to transfer rotating force to the impeller. Also, depending on your particular vehicle make and model; your engine may use a serpentine belt, drive belt, or timing belt to turn your water pump. Although a shaft seal isolates coolant from the bearing assembly; your water pump housing has a weep hole; to allow coolant to exit if your water pump develops a leak.
Most of the time, when a water pump fails; the noise is caused by damage to the bearings.
Water Pump Bearing Failure
One way to check for worn out or failed water pump bearing; is to check for water pump shaft movement.
So, with a faulty bearing, you can often hear a squealing, howling; or sometimes a grinding noise coming from the front of the engine. Even if you don’t hear any noises, apply the next steps:
- To isolate the source of the water pump noise, you can use a large screwdriver; or a length of rubber hose to isolate the source.
- Start your engine. Keep your hands and screwdriver or hose away from moving parts.
- Touch the front of your water pump housing; with the tip of the screwdriver shaft or one end of the hose.
- Put the other end of the screwdriver or hose against your ear. Finally, if the bearings are worn out or damaged; you’ll clearly hear the noise coming from your water pump; as the bearing causes a rough rotation of the pump shaft.
Also, be aware that a loose or slipping drive belt, an AC compressor, alternator, steering pump, belt tensioner; or another accessory driven by the belt may also cause a similar noise.
Water Pump Shaft Failure
First, check the water pump shaft and pulley for signs of damage or movement.
Furthermore, on vehicle models where a serpentine, drive or timing belt runs the water pump; you may need to remove the belt to manually check the water pump pulley:
- Wiggle your pump pulley with your hand. If you notice damage or movement, replace the water pump.
- Rotate the pulley by hand. It should turn freely but not feel loose or rough; otherwise, replace the water pump.
- On vehicles where the radiator fan attaches to the water pump assembly; you can grab the fan and carefully wiggle the fan. If you notice movement, most likely the water pump will need replacing, but check that all mounting bolts are tight. And carefully examine the fan as well. With enough time, a loose or damaged fan will cause the water pump to fail.
Important Note !
So, when replacing a water pump run by a timing belt; always replace the timing belt at the same time; especially if the water pump was leaking. A coolant contaminated timing belt will have a reduced service life. On the other hand, a worn out timing belt may break and damage your new water pump. In most applications, the water pump and timing belt have about the same service life period (50,000 miles or more). So, you’ll save time and money by doing both at the same time.
So, you should begin diagnosing a water pump failure; as soon as you suspect something is wrong. Finally, an early diagnostic can save you thousands of dollars in repairs.
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