A pulley is an important part of your vehicle’s cooling system. It helps power the water pump, which keeps your engine safe from overheating. Without it, the pump will most likely fail, causing severe damage to your engine. Because of this, it’s important to know when the pulley starts to fail.
What Is a Water Pump Pulley?
All engines need some type of cooling system to keep them from overheating. Most modern vehicles have a water pump, which injects coolant from the radiator to the engine. As it circulates through the passages, the coolant picks up heat from the engine.
While its design can vary depending on the vehicle’s make and model, a water pump has five basic parts: the housing, impeller, bearing, seal, and pulley. The pulley, also known as the hub flange, connects the bearing shaft assembly to the impeller with blades that spin very close to a specially shaped reaction surface to move the coolant as efficiently as possible.
Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.
Pro Tip: The water pump pulley is sometimes a part of the water pump that can’t be replaced without replacing the pump. If the pulley has an issue on this type of component, the whole pump will need replacing.
However, it’s also very common to have the pulley as a separate part that has to be bolted to the water pump shaft with three or four bolts. On older vehicles, the fan and the water pump pulley would both be bolted to the water pump shaft so the belt could drive the water pump and the fan at the same time.
Most water pump pulleys never fail. However, in some cases, they can fail depending on how they’re designed.
On older vehicles, the fan and the water pump pulley would both be bolted to the water pump shaft so the belt could drive the water pump and the fan at the same time.
– Richard McCuistian, ASE Certified Master Automobile Technician
Symptoms of a Bad Water Pump Pulley
It can be hard to diagnose a bad pulley, especially when there are different reasons why your water pump is making unusual noises. Luckily, there are other bad water pump pulley symptoms you can look out for.
Whining Noise
A bad water pump pulley noise will often sound like high-pitched whining. Over time, a pulley can get rusty and start to crack between its bolt holes. This can cause the hub to loosen, making a whining sound when spinning.
Grinding Noise
If you hear grinding instead of a whining sound, then the issue is most likely the pulley’s bearings and not the pulley itself. A grinding or squealing noise from the front of the engine is most likely due to faulty bearings. The pump’s bearings will naturally wear over time, but static overload, corrosion, and misalignment can also speed up the process.
Physical Damage
If you notice any physical damage on the impeller or bearings, then it might be because of a bad pulley. A bad pulley will most likely become loose and wobble, causing vibrations to occur. These vibrations interfere with the torque of the impeller, causing it to spin in an unbalanced manner. This can damage the impeller and bearings, causing them to fail early.
Visible Wear on the Pump and Belt
Visible wear on any part of the pump might be a sign that it’s time to replace the whole pump, including the pulley. Corrosion is often caused by using the wrong coolant or air seeping through a faulty pressure cap. If you notice any rust or tiny holes on the pump, then the corrosion has likely spread to other parts of the pump, including the impeller, bearings, and pulley. This can also cause the belt to slip from the pulley, which can lead to further damage.
A broken or cracked belt can also be a sign of a bad pulley. If the pulley is too tight, it can restrict the belt’s movement and damage it over time. A loose pulley can also cause the belt to slip and the cooling system to fail.
Overheating Engine
If you notice a spike in your temperature gauge, then it might be because of a bad pulley. A bad pulley won’t be able to power the impeller, so the coolant won’t circulate and pull heat from your engine. This can cause your engine to overheat, which can cause lasting damage to your vehicle, such as a blown head gasket or a seized engine.
What Does a Water Pump Pulley Do?
The water pump pulley transfers the drive belt’s movement to the bearing spindle. It powers the impeller while mediating the amount of torque that passes through. In other words, it makes sure the impeller doesn’t spin too fast or too slow, so the impeller can maintain the liquid’s pressure and flow inside the water pump.
Water Pump Pulley FAQ
While your engine can still run with a bad pulley, it isn’t a good idea to drive your vehicle around for too long. The pulley is a vital component of your vehicle’s cooling system. Without it, the cooling system will most likely fail, and the engine might overheat. This can seriously damage your vehicle’s pistons, cylinders, and more.
Because of this, it’s best to avoid driving and to get a replacement as soon as possible. You can save your vehicle from further damage while saving yourself from a bigger repair bill.
Like the other components of a water pump, the pulley can last around 60,000 to 90,000 miles. This can change depending on your vehicle’s make and model, how you drive, and how often you drive. Keeping up with your vehicle’s maintenance schedule can also increase the pulley’s lifespan.
While lubricants can prevent rust and corrosion, you don’t need to apply them on the pulley or any part of the water pump. Most modern vehicles have self-lubricating water pumps, so adding lubricant is unnecessary. Good quality pumps should last for a long time even without any lube or oil.
Repair costs will vary on several factors, such as your vehicle’s make, model, and the product’s brand. On average, however, a water pump pulley can cost anywhere from $20 to $140. In some cases, you’ll need to replace the entire water pump and not just the pulley. This can cost you anywhere from $10 to $1,120.
If you suspect that you have a water pulley problem, it’s best to consult a mechanic so that they can identify every component that needs replacing.
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