How to Stop a Squeaky Belt: Quiet Serpentine Belt [2024]

Does your engine squeak when you start your vehicle or squeals when you turn the wheel? 

If it does, then it means something isn’t right under the hood. 

Most modern vehicles used serpentine belts to drive engine accessories like the power steering pump and water pump. 

However, the belt can start to make noise if it is misaligned or when the surface hardens. 

If you’d like to know how to stop a squeaky belt, this article will lay it all out in a simple step-by-step process. 

Keep in mind that these may be temporary fixes and you’ll need to replace the belt to ensure the safety of you, your loved ones and the vehicle itself. 

What is a Serpentine Belt and how does it work?

squeaky serpentine belt engine components

Simply put, the serpentine belt is a continuous flat rubber loop. 

The inside face of the belt has grooves or ribs while the outer face is usually smooth. 

The grooves and ribs on the inner surface ensure that the belt stays in place and increases drive friction. 

The belt drives multiple components of a vehicle engine and performs tasks that used to require multiple belts. 

Before 1990, most vehicles used two or more V-shaped belts to drive different devices on the engine 

These belts would drive the water pump, alternator, power steering,  air conditioning compressor, air pump and other devices on different vehicles. 

They were all driven by the driveshaft and required a lot more space and hardware. 

However, today the serpentine belt is driven by the driveshaft and loops around the various devices. 

Idler pulleys or belt tension are used to redirect the belt and keep it tight so it can maintain contact to drive each component. 

The serpentine belt drives all auxiliary equipment on a vehicle. 

This includes the power steering pump, alternator, air conditioning water pump and others 

Causes of a squeaky serpentine belt

A serpentine belt has a life expectancy between 50,000 – 100,000 miles. 

However, it can fail before that time if it’s not maintained properly or due to some other problem. 

How often the serpentine belt squeal and when the noise occurs will provide you with more information about the cause. 

Here are a few reasons why your serpentine belt may squeak or squeal. 

Wear and Tear

The serpentine belt may stretch over time.

This can cause it to slip on a pulley or two and result in the squeaks you hear.

If that’s not the case, then it could be that the ribs or grooves on the inner face of the belt are worn or damaged.

When that happens, it impedes friction and creates squeaking sounds.

Pay attention to the edges of the belt also as they may show signs of damage or wear as well.

Misaligned pulley or tensioner 

If the belt is misaligned, the belt can slip or wear unevenly. 

It can also give the outer face of the belt a hard glazed look and feel.  

Moreover, it can put more or less pressure or drive friction on different auxiliary functions. 

If this happens, you could experience a low battery charge, an overheating engine, less power steering assistance or poor air conditioning performance. 

Improper belt installation 

A belt that isn’t properly installed may still be able to operate all or most of the mechanical and electrical functions powered by the drive shaft. 

However, you will hear squeaking noises. 

This can happen due to the curvature of the belt over some pulleys or wheels. 

Be sure to check the manual and install the belt the correct way. 

Other than creating annoying sounds, an improperly installed belt can affect belt tension and lead to damages to pumps, motors and brackets.

Weather conditions 

Temperature and moisture can play a role in the amount of noise the belt makes. 

if you can only hear the squeaks when there is early morning dew or heavy fog it means that there is moisture on the belt. 

This will eventually disappear as the engine starts to warm up. 

On the other hand, cold temperatures will stiffen the rubber in the belt.

This will cause it to make a noise when you start the engine. 

As the engine warms up and the belt starts to move, the sound should go away. 

Oil or grease on the belt 

If the belt looks shiny or glazed, it could mean that there is oil or grease on it. 

It can also give you an idea of other issues under the hood like a leak or if a pulley or tensioner is out of alignment, seized or damaged. 

Check to see if any coolant oil, grease spill or leaks are getting on the belt. 

Oil or grease can deteriorate the belt material and have an impact on the way it operates. 

Defective bearing

Sometimes it’s not the belt that squeaks but a defective bearing.

Pop open the hood and listen closely.

If you can isolate the sound in one area, then it could be a faulty bearing.

Shut the engine off and examine the pulley or wheel that the sound is coming from.

If the metal surface of the pulley or wheel is glazed or has particles from the belt on it, it may be seizing.

If it doesn’t spin freely, you’ll need to replace the pulley or wheel. 

How to figure out why your serpentine belt squeaks

how to make serpentine belt stop squeaking guy fixing

A squeaky serpentine belt can be a result of several different issues. 

The first step in fixing this problem is to diagnose the reason for the sound. 

Keep in mind that you need to dress accordingly and wear safety gear like goggles when trying to diagnose the problem.

Loose clothing, jewelry and hair can put you in harm’s way with the moving parts of the vehicle’s engine.

Check for wear

Inspect the belt both visually and physically. 

Check for cracks in the rubber since this can happen over time. 

The rubber may also become thinner or show signs of wear along the edges. 

if there is wear at the edges of the bell, it indicates that it is misaligned or a pulley is warped or failing. 

Additionally, check the inner face of the belt and see if the grooves or ribs are worn. 

You can use a belt gauge to check the groove depths since they get deeper as they wear. 

If any part of the belt is shiny or wet, it can indicate that there is a leak somewhere.  

A damaged serpentine belt can help you identify other issues with the engine or auxiliary components. 

Repair any issues you find and replace the damaged belt. 

Adjust the tensioner  

Try pushing the belt inward. 

If you can do so more than ½” between the pulleys, the belt needs to be tightened. 

You can also try twisting the belt and if it does more than halfway over, it is too loose and needs to be tightened.  

Tensioners are hydraulic, spring-loaded or manually adjustable. 

Figure out which one your vehicle uses by consulting with the owner’s manual. 

If it has an adjustment bolt then it can be manually adjusted. 

Most times it will be as simple as loosening the pivot bolt and the adjustment lock bolt. 

These are both often located on the alternator.

Slowly tighten the adjustment bolt until the belt is at the recommended tension. 

Keep in mind that when you tighten the adjustment lock bolt and the pivot bolt after adjusting, the belt will tighten a tiny bit more. 

Check the tension again after all the bolts are tightened. 

A belt may stretch and become loose or a belt tensioner or pulley can become loose, misaligned, or damaged. 

If the belt cannot be tightened any further or keeps getting loose, you may need to replace both the tensioner and belt. 

Check the pulley alignment 

The alignment of the belt relies on the proper alignment of the pulleys. 

If the grooves in the pulleys aren’t aligned correctly, the belt will squeak or squeal.

This can also cause extensive damages to the belt and auxiliary components. 

Look for excessive wear or damage on the belt which is a common indication of misalignment. 

You can use a laser alignment tool or straight edge to check alignment. 

All pulleys need to be parallel horizontally and vertically. 

On the other hand, you can simply reverse the belt to check alignment. 

Remove the belt, flip it 180 degrees and reinstall. 

Fire up the engine and listen carefully. 

If the squeaking stops when the belt is reversed, it means the pulleys are misaligned. 

If the noise is the same then it is not a misalignment issue. 

Pulleys and shafts should be parallel to each other and have the same angle. 

In some cases, pulleys may have a vertical or horizontal angle misalignment which is caused by a belt that has been tightened too much or an improperly placed or loose attachment. 

Parallel misalignment occurs when a pulley slips on its axle or a component needs to be moved forward or back. 

Check the pulleys

Loosen or remove the serpentine belt and check the bearings of pulleys and attachments. 

All the pulleys should spin freely and quietly. 

If not and you hear a grinding sound or experience friction, the bearings may be worn or damaged and should be replaced. 

Use chalk or a grease pencil and mark the face or edge of the pulley, reattach and tighten the belt. 

Start your engine and drop it into a slow idle. 

If the mark and the sound seem to align then the bearing is damaged. 

Spray the belt with water 

You can perform this water test after visually inspecting the belt.

Turn the engine on, go into a low idle and open your hood.

Take a spray bottle with water or atomizer containing water and spray a small amount of water on the inner face of the belt just before a pulley.

Try to keep your mouth closed and your safety goggles on because some of the water may be redirected back to you.

After spraying the water, listen closely to the noise.

If the noise increases, it means the belt is loose, worn or both.

If the noise stops for a little while and then returns to normal, it means there’s a misaligned pulley or a worn belt.

Check the belt and if there’s no sign of wear, the issue is the pulley.

If the noise doesn’t change at all, the problem may be a failing auxiliary pump or motor.

Remove the belt

Last but not least, remove the belt.

Turn the engine on but don’t leave the engine on for too long without the belt.

 if you can hear the noise, then the serpentine belt or an auxiliary part isn’t the problem.

It could possibly be an issue with the idler pulley, crankshaft pulley or water pump.

How to stop a squeaky belt

If you’re wondering how to make serpentine belt stop squeaking, try these steps.

Apply belt dressing

A key point to note is that this method is a temporary solution and you need to get the problem fixed as soon as you can. 

 If your serpentine belt squeaks, using a belt dressing is one way to solve the issue.

You’ll find many products on the market to quiet belt noise.

These belt dressings and conditioners are applied to the inner ribbed face of the belt.

They claim to improve friction, belt life and remove contaminants and water.

Proceed with extreme caution when using these products on the belt.

Most belt dressings will have a lubricant or tacky agent that makes the rubber supplier.

They can also cause the belt layers to separate.

Some people may try using WD40 and while it can remove moisture from metal, it can damage the rubber compounds in the belt.

It can also damage bearings, wiring or other components of the engine.

Check out one of the best belt dressing below.

  • Extends belt life
  • Prevents belt from slipping
  • Conditions the belt to eliminate squeaking

2. Using a bar of soap

If there’s dirt, oil or grease on a pulley, it can cause the belt to slip.

If that’s the case, apply bar soap to the ribbed side of the belt.

This may reduce the slipping and quiet the noise temporarily.

Try to figure out how the pulley got dirty in the first place and fix that issue.

After that, clean the pulleys using an approved cleaner.

3. Tighten or align the belt

Check and make sure that all the pulleys and the belt are in perfect alignment.

Also, pay attention to the tension of the belt.

Sometimes, the belt just needs to be tightened to stop the noise. 

If there is a misalignment issue, make the adjustments and tighten the belt.

This can be a long-term fix if it’s done correctly.

4. Replace the belt

If all else fails, then it is time to replace the belt. 

A belt can still look good after its life expectancy is up.

However, if your engine is noisy, replace it immediately.

5. Repair or replace bearings

If you find a defective bearing during your examination, then you have to repair or replace it

You can either do it yourself or take it to a mechanic.

Replacing a bearing can be a long-term fix if done correctly.


The serpentine belt plays an important role in your vehicle.

If you hear any weird and new noises coming from under your hood, an issue with the belt can be the culprit.

Examine this issue as soon as possible and apply the methods mentioned in this article to help quiet serpentine belt making noise.

Temporary fixes are just short-term solutions so make sure you don’t rely on them too much.

Try to get things sorted in the best and safest way possible so that you are guaranteed safety when you’re on the road.

Check out our alternator noise and lifter tick posts if you’re hearing sounds coming from these components of your vehicle.

Leave a Comment