How To Make Serpentine Belt Stop Squeaking In 5 Simple Steps

how to make serpentine belt stop squeaking

Do you hear a squeaky noise when you start your engine?

Besides it being so annoying, it can also cause damage to your vehicle.

The noise sometimes can be so loud to distract your focus on the roads and cause accidents.

Do you know?

According to National Highway Traffic Safety Administration (NHTSA), in 2018, 2,841 people were killed and an estimated 400,000 people were injured in motor vehicle crashes involving a distracted driver.

So it’s important to treat your squeaky car belt.

In this article, we’ll see what a serpentine belt is and the reason due to which the belt is creating noise.

I’ll also explain the most effective ways to make the serpentine belt stop squeaking.

Related: How to soundproof a car trunk from irritating noises?

What Is A Serpentine Belt And Its Purpose

what is a serpentine belt

A serpentine belt is a single, continuous flat rubber loop used to drive multiple devices of a vehicle engine, such as an alternator, air pump, water pump, power steering pump, etc.

The belt is passed over more than three pulleys with a large angle to avoid slipping and idler pulleys and/or belt tensioner is used to press against the back of the belt, giving the belt a serpentine shape and thus the name.

The inner part of the belt has ribs and grooves and the outer part is usually smooth.

The ribs and the grooves at the inner part of the belt help the belt to stay in place and boost drive friction.

At older times, most vehicles used two or more V-shaped belts to drive different peripheral devices on the engine.

All the belts were driven by a driveshaft and required much more space and hardware.

But, today all the different belts are replaced by one serpentine belt which is driven by the driveshaft and loops around various devices.

The serpentine belt drives different peripheral devices in an automobile, such as a power steering pump, water pump, air conditioner, etc.

Failure of the belt will result in the failure of these functions as well.

Reasons For A Squeaky Serpentine Belt?

A serpentine belt drives different devices in your car and so it is normal for it to get damaged as time passes.

A serpentine belt has a life expectancy of 50,000 – 100,000 miles. However, it can fail before it, if not maintained properly.

Mostly, the belt squeals when it can’t stay in position in any of the pulleys.

Another reason why the belt slips may be due to the moisture present at the inner face of the belt.

Some other common reasons for belt noise include:

1. Misaligned Pulley Or Tensioner

If it’s not the moisture that causes the belt to slip then the tensioner or pulley may be the reason behind it.

The tensioner or pulley may be misaligned that causes the belt to slip or wear unevenly.

You can visit a mechanic and he will inspect your car and tell you if the pulley is aligned properly or not and will fix it for you.

Besides this, misalignment can also put more or less pressure or drive function on different peripheral devices of the engine.

Misalignment can cause:

  • Overheating engine.
  • Less power steering assistance.
  • Low battery charge.
  • Poor AC performance.

2. Improper Installation

If you have installed a new serpentine belt in your car, then there might be a chance that the process was not done properly which causes the belt to squeak.

In that case, you need to check the owner’s manual and make sure that everything is in place.

You should ensure sure that the belt is tight enough to stay in position after the engine starts.

Besides creating noise, improper installation of the belt can cause damage to:

  • Motors
  • Pumps
  • Brackets

3. Wear And Tear

With time everything wears out, and so does your serpentine belt.

The belt may wear with age, causing it to slip over the pulley system and thus create squeaky noises.

The ribs and grooves at the inner face of the belt may wear out, which hinders friction and creates noise.

4. Mother Nature

Do you hear some squeaky noise from under the hood on a foggy day when you start your car and it usually fades away with time.

Cold temperature and moisture also cause the belt to squeak.

In the morning the temperature is usually cold which is the cause behind the moisture present on the belt.

However, the noise fades away after starting the car as the engine warms up.

5. Oil Or Grease Contamination

Another reason that causes the belt to squeak is the contaminants present on the belt.

Look for any coolant, grease, or oil spills, or leaks getting on the belt.

The contaminants may worsen the belt material and affect its operation, thus causing noise.

How To Make Serpentine Belt Stop Squeaking

A defective belt is not only the cause for some squeaky noises but it indicates that the mechanism under the hood is not working properly.

We’ve already seen several reasons, why your belt is squeaking.

If you hear the noise only when the engine starts or while accelerating, then the belt could be loosened or worn out.

If the tensioner or pulley system is not alright then you would hear a continuous squeal noise.

Ideally, you should visit a mechanic to solve these problems, but if you are planning to save some money by doing it yourself, then you can try the following options:

Safety Note:

Avoid wearing jewelry, and loose clothes while working on your engine. Also, cover your hair and wear safety gloves and goggles to prevent accidents.

1. Check The Belt For Wear

The first thing that you need to do to soundproof your belt is to check the wear on the belt.

Carefully look for cracks in the belt, which usually occurs with age. As the belt gets older it becomes thinner and starts to develop cracks and splits.

If the belt is misaligned or a pulley is failing then the belt develops cracks at its edges.

You must check the inner face of the belt for damage or missing rubber and the overall thickness of the belt.

You can perform a 5-minute water test to find out if the squeaking noise is due to a worn or loose belt.

To do the test all you need is safety gear like goggles and a spray bottle.

Turn the engine on and leave it to low-idle and spray some amount of water on the inner part of the belt using a spray bottle.

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

If your belt is worn then you need to change it immediately to get rid of all those squeaky noises.

2. Adjust The Tensioner

If you are able to push the belt inward more than 1/2″ between the pulleys, then you need to tighten the belt.

Tensioners are manually adjustable if it has an adjustment bolt. You can find it out in your vehicle owner’s manual if you have one.

Loosen the belt pivot bolt and the adjustment lock bolt which are located on the alternator and then slowly tighten the adjustment bolt till the belt has a recommended tension.

After adjusting the pivot and adjustment lock bolt, you need to check it again to ensure that the process was carried properly and the belt is effectively tightened.

If the belt doesn’t tighten anymore or becomes loose again, then the tensioner and the belt may both need to be replaced.

3. Check The Pulley Alignment

To check the alignment, we first need to loosen or remove the belt.

After removing the belt, the pulley should spin quietly and freely.

But, if you hear some grinding or friction noise, then the bearing may be worn or damaged and needs to be replaced.

To know if the bearings are the cause of the noise, mark the edge of the pulley with chalk and reattach the belt to the pulley.

Now start the engine and see if the mark and the noise align. If they do, then the bearings are worn.

If the bearings are fine, then the pulley may be misaligned.

To check if the pulley is misaligned, remove the belt, flip it 180 degrees and reinstall the belt.

Then start the engine and listen.

The squeaking noise will be temporarily reduced, meaning the pulleys are misaligned. But, if there is no change in noise, then the noise is not caused by a misaligned pulley.

4. Apply Belt Dressing Spray

There are several spray-on compounds that claim to quiet the belt noise but among them, the aerosol dressing spray is the best.

An aerosol belt dressing spray is sprayed on the ribbed side of the belt which helps to improve friction.

The spray also helps to remove water and dirt from the belt which may cause the belt to squeak.

Applying a belt dressing is a temporary solution and you need to find the root cause of why your belt is squeaking.

After a certain time, you will again start to hear noise from the belt.

Also, most dressing sprays have a lubricant or a tacky agent in them, that makes the belt stretch or slip.

This may worsen the problem after the friction effect of the belt wears out.

Note: The spray may cause eye or skin irritation, so wear safety gear while applying the spray.

5. How To Fix A Squeaky Belt With Soap

There may be dirt, oil, or grease present on the pulley that causes the belt to squeak.

Spraying soapy water on the belt is the fastest and the simplest way to get rid of the squeaky noises.

You need to apply the soapy water on the ribbed side of the belt, which helps to reduce the noise for a short period of time.

Since it lasts for a short duration of time, so you can’t be applying soapy water on the belt every time instead you need to identify why your belt is squeaking and fix it permanently.

Wrap Up On How To Make Serpentine Belt Stop Squeaking

how to soundproof a serpentine belt

A serpentine belt is a major part of your vehicle that powers the power steering pump, water pump, air conditioning, and alternator.

So besides making noise it can affect all these drive functions as well.

I have mentioned all the reasons why your serpentine belt may be squeaking and the solutions to fix them.

You can either visit a mechanic or do it yourself if you understood the process well to fix a squeaky belt.

Also, don’t rely too much on temporary solutions as they will not help you in the long run.

I hope this article helped you to fix your squeaky serpentine belt. If you liked this article then do share it with your friends too.


Q1. Can I spray Wd40 on the serpentine belt?

No, it’s not good to spray Wd40 on the serpentine belt.

Wd40 helps to remove moisture from the metal, spraying it on the serpentine belt will damage the rubber compounds in the belt.

It may temporarily reduce the noise, or who knows make it even worse.

Besides the belt, Wd40 can also damage the bearings, wirings, and other engine components.

Q2. How much does it cost to make a serpentine stop squeaking?

If you want to replace the belt, then a new belt would cost you between 30-75$.

Some models require replacing the tensioner also with the belt, which would cost you an extra 40-70$.

If you fix the belt yourself, then you would save the mechanic charges ranging from 125$ to 225$ an hour.

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