What Are the Main Signs of a Bad Water Pump?

In order to stay cool and run properly, a car needs a water pump. If it malfunctions for some reason, the car will not only stop working but the engine might break to the point of no repair.

Obviously, you don’t want that to happen to your beloved vehicle, so you better stay on the lookout and act immediately — as soon as you notice the first signs of a failing water pump.

What are the signs of a bad or failing car water pump.

Why Is the Water Pump So Important?

Before I tell you what the symptoms are, you should know how a water pump works and why you need it in the first place.

Namely, a water pump is an essential part of the engine cooling system. With the help of a serpentine or auxiliary belt, the pump moves the coolant liquid from the engine block through hoses, and into the radiator, where it cools down. Then, the now cold liquid circulates back into the engine and the whole process repeats again.

Essentially, the main purpose of a water pump is to ensure that the coolant liquid reaches the engine to prevent it from overheating.

If it does overheat, serious consequences can occur. For instance, the head gasket might crack, causing the antifreeze to spray everywhere. Repairing that will undoubtedly be a nightmare, costing you a lot of money, time and effort.

In other words, if your water pump is faulty, the whole cooling system will be compromised. For that reason, you need to call an experienced technician as soon as you detect any of the following symptoms.

Signs of a Bad Water Pump


The first and most important sign of a water pump failing is the presence of a coolant leak. The seals on the pump wear out over time and so the coolant liquid might start pouring out the bleed valve. However, depending on the severity of the leak, you might not even notice it.

You see, when your car isn’t running, the coolant stands still in both the engine and the coolant reservoir. Therefore, even if the pump’s seals are going out, the coolant won’t leak out until you start the engine again.

In addition, minor leaks can dry out on the pump itself. So, you might not even notice the leak until it’s too late, especially if you don’t open up the hood for a routine inspection.

On the other hand, a major coolant leak will surely leave a pool of bright-colored coolant liquid underneath your engine, which you won’t be able to miss. Depending on the type of coolant, it could be red, green, blue, or orange. In any case, you can’t mistake it for oil or water.

Furthermore, most modern cars will give off a “low coolant level” warning. If you regularly top up your coolant liquid, this warning usually means you have a leak in your cooling system.

High-Pitched Whining Sounds

Depending on the exact issue, you might hear a screeching, grinding, or a whining noise if your water pump is faulty.

A screeching noise is usually a sign of a failing serpentine or accessory belt. On the other hand,a whining sound is most likely a sign of an improperly calibrated belt tensioner. Your belt might be too tight, or too loose, and that can cause the whining noise.

Fortunately, you can solve both of these problems without too much trouble, provided that you go to the mechanic straight away. If your pump is still good, replacing and re-tensioning the belts won’t cost you too much.

However, if you hear a grinding sound coming from your water pump, your bearings have probably worn out. In that case, you’ll have to replace the entire pump right away, before it causes further damage to your engine. If the bearing goes out completely, your engine will overheat before you even realize what’s going on.

Engine Overheating

Typically, although it depends on your car, driving style, and weather conditions, the engine heats up a bit, but not more than halfway to the red zone.

And if the car’s water pump is faulty, you’ll most likely see the temperature gauge move up to a dangerous level. You might reach the red zone after only a few miles of normal driving.

At that point, most modern cars will give an overheat warning and a recommendation to stop the car. In addition, some cars might enter a “limp home mode”, severely limiting your max speed and engine RPM.

Unfortunately, older cars will run until they blow, and it’s up to you to notice the problem and stop in time.

Smoke or Steam

Finally, if your temperature gauge isn’t working and you drove the car with a bad water pump for too long, you’ll surely notice steam coming from the radiator at some point. And if you do, you should stop immediately. Pull over to the nearest safe spot, call AAA, and tow your car to the mechanic.

If you don’t do that, you might blow up your engine. The head gasket can break, the pistons can burn, and the cylinder head might crack or deform beyond repair. Then, you’re probably looking at least at a couple thousand in parts and labor, and a completely new engine.

However, people often mistake steam for smoke, which is indicative of another issue.

When the water pump belt wears off, it can easily burn up. You might notice a cloud of black, foul-smelling smoke coming from your engine. Just like with the steam, you should pull over immediately if you notice it. Even though your water pump might still be saved, you still risk an overheated engine if the belt breaks.

What to Look Out for When Inspecting a Failing Water Pump

Every once in a while, you should check your car’s engine bay for any visible issues. Check the fluid levels, look out for any leaks, and see if anything is loose or worn out.

When you get to the water pump, you should look out for the following few signs of water pump failure. Keep in mind — the earlier you notice the issue, the more you’ll save in repairs.

Rust and Corrosion

If you see rust appearing on the surface of your water pump, you should replace your coolant immediately. Your coolant might be incompatible with the cooling system, or you put two different coolants at the same time. In addition to causing rust, contaminated or incompatible coolant can cause damage to your engine and coolant hoses.

Deposit Buildup

A minor leak can spray coolant all over your pump and belt, which dries out before reaching the floor underneath your car. If you don’t notice the leak on time, the coolant can build up on the surface of the pump, eventually ruining the seal completely.

On the other hand, if you notice a deposit buildup on a freshly replaced water pump, it was probably not installed properly. In that case, you should contact the mechanic who installed it to resolve the issue.


Cavities or pockmarks on the water pump surface are typically a result of exploding air or vapor bubbles inside the pump. In addition, the cavities rust more easily than the rest of the pump, causing even more damage than usual.

Keep in mind, your engine block might suffer from cavitation as well. So, if you notice pockmarks on your water pump, replace both the pump and the coolant as soon as possible.

Final Thoughts

In most cases, a malfunctioning water pump results in an expensive trip to the mechanic. The water pump is an essential part of the engine. That being said, you have to use special tools just to remove it.

In addition, you have to tighten all the belts exactly as the manufacturer specifies, otherwise you’ll wear the pump out too soon. Therefore, the best thing for you to do is be on the lookout for warning signs and replace the water pump accordingly.

I sincerely hope you won’t have trouble with your water pump until the time comes for your next engine service. Good luck!




Scroll to Top