4 Reasons A Belt Will Squeal (And Easy Ways To Silence It)

Knowing the reasons a belt will squeal is the only way to stop the squeal for good. If you have a car or any vehicle, you may notice that there are times when it squeals each time you start your engine. The reason behind that is the rubber belt. However, why does a belt squeal?

Engine belts screech or squeal because the rubber belt slips on the metal pulley. Commonly, a slipping and squealing belt will result from one of 4 things:

  1. Incorrect Installation
  2. Leaks
  3. Misaligned Pulley And Tensioner
  4. Wear And Tear
Reasons A Belt Will Squeal

Fortunately, you can fix a squealing and damaged belt. But before you can do that, you need to know the reasons behind the noise that it makes.

Also read: Lifter Ticking Noise In Car Engines—Fixes and Treatment

Reasons A Belt Will Squeal

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The Belt system differs depending on the type of vehicle that you have. Some vehicles either have a long serpentine belt or multiple small accessory belts. Regardless of the differences, they play an essential role in transferring the rotational energy that the engine creates to the essential accessories.

As a result, the belt can keep your air conditioning, fan, water, power steering pump, and alternator working. In addition, the belt prevents your battery from dying.

But since belts work continuously while your vehicle is running, it acquires damage, which causes it to make squealing noises.

As mentioned, the noise that a squeaky belt makes results from the rubber belt slipping on the pulley. Such can happen due to a number of factors.

Incorrect Installation

The belt must have enough tension when you are installing it. Additionally, it needs to be re-tensioned minutes after running the engine. If you skip these steps, the belt will squeal in no time, and you will have to replace it if not repaired promptly.


Water, leaking fluids, and other fluids coming from one part of the engine can contaminate the belt. A wet belt will produce squeaky noises, which you will hear every time you start the engine.

Misaligned Pulley And Tensioner

If you did not align the tensioner and pulley appropriately with the belt system, the rubber belt will slip and begin making unwanted noises. For this reason, you should always double-check your belt to see if it is in proper alignment.

Wear And Tear

No rubber belt would last forever. So, as you use your vehicle, the belt runs without rest, which eventually causes it to lose its stiffness. Wear out can also cause the surface of the belt to become brittle, glazed, or cracked.

Also read: Why Your Car Brakes Squeak When Stopping Slow

How To Fix A Squeaky Belt

There is nothing worse than having a perfect car that squeals every time you start the engine up. The noise always comes from the belt, so such is the first thing you need to check once you hear a noise from your engine.

While the squeaky noise sound like your vehicle is on its dying days, there are several things that you can do to fix the belt.

Below are the things that you can do to fix your squeaky belt:

1. Identify The Noise Source

The squeaking sound whenever you start your vehicle comes from the belt slipping. Meaning it cannot be due to the timing belt, so you should not panic the moment you hear your engine wailing.

The noise does not come from timing belts because they have teeth that prevent them from slipping. If they did, they would damage your engine in an instant. That said, you need to look at the other belts.

Ninety percent of the time, the main reason for the squealing noise that you hear from your engine is the auxiliary serpentine belt. Another cause is the fan belt, which acts as an electric for most modern cars.

2. Dress The Belt

After finding the noise source, the next thing that you need to do is to dress it. You can do this step by simply buying a belt dressing and putting. The dressing works by protecting and moisturizing the belt.

A dry belt will produce howling noise. For this reason, you need to dress it to ensure that it has enough moisture.

You need to spray the belt dressing on the belt while the engine is running. This way, you can make sure that the entire belt will be covered.

Dressing the belt does not promise that the problem will be gone entirely. Still, it is worth giving it a try as the dressing would at least dry the noise.

3. Tighten The Belt

A tensioner holds your belt in place. If you are unsure where the tensioner is, you can check the Haynes manual to find out where it is.

Once you found the tensioner, you should be able to loosen the bolt while holding it in place. This way, you will be able to move the bolt to put more tension on the belt. It is important to note that you need to do this process carefully.

If the belt has less tension and less play, there will be less chance of noise. Finally, tighten up the bolt again to see if the belt will no longer squeal.

4. Replace The Belt

There are times when fate will damage the belt beyond repair. Suppose you did all the repair methods above and the noise continues. In that case, that is an indication that you already need to replace the belt.

Moreover, serpentine belts are everyday items that you can get. For this reason, you do not need to be a mechanic to replace it.

  • To replace the serpentine belt, you need to:
  • Loosen the tensioner to remove the old belt.
  • Check if the tensioner has any damage. The tensioner is a small bearing. To check its condition, spin it and listen to if it will produce grinding noises. If there is, you need to replace the tensioner as well.
  • Put the new tensioner and serpentine belt in place by tightening the bolt off.

If it is the fan belt that squeals, you will not have a tensioner. But you may need to loosen the bolts on one side of the alternator to take the tension off the fan belt.

Finally, slip the new fan belt on and tighten up the alternator.


  1. What Makes a Belt Squeal?, Titan Auto and Tire, https://titanautotire.com/what-makes-a-belt-squeal/
  2. Why Does My Fan Belt Squeal and How Do I Stop It, Berryman Products, https://www.berrymanproducts.com/fan-belt-squeal-stop/
  3. Andrew Gardner, What is Belt Dressing or Belt Conditioner?, Blain’s Farm and Fleet, https://www.farmandfleet.com/blog/belt-dressing/ Accessed August 12, 2021.
  4. HOW TO FIX A SQUEAKY BELT ON YOUR VEHICLE, Haynes.Com, https://haynes.com/en-gb/tips-tutorials/how-fix-squeaky-belt-your-vehicle/

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