Squeaky Serpentine Belt Noise Fix: 4 Simple Ways to Stop Squealing

Have you ever heard a squeaky noise when starting your car or turning the wheel? It’s annoying and even a bit embarrassing, but the noise is telling you there’s something wrong. A squeaky noise could be a serpentine belt noise, so it’s time to look under the hood and see what’s going on. 

After diagnosing a squeaky serpentine belt, your first question may be how to make the serpentine belt stop squeaking? Well, that’s what we’ll explain today! We will look at what a serpentine belt is and what it does. 

But more importantly, we will provide a simple guide on how to diagnose your serpentine belt squeal and provide 4 simple solutions for this issue. That way, you can enjoy quiet and safe rides once more. Without further ado, let’s get into the ultimate guide on serpentine belt noise! 

What Is a Serpentine Belt and What Is Its Function?

Serpentine Belt
Source: Wikipedia. 

The serpentine belt is a continuous flat rubber belt that drives a variety of components in the engine. Including the alternator, water pump, air pump, power steering pump, and more. 

The inside of the serpentine belt features grooves that allow it to stay in place and increase drive friction, while the back of the serpentine belt is nice and smooth. 

Before the serpentine belt was introduced in the 1990s, vehicles required several belts to perform all the individual tasks that the serpentine belt is designed to do on its own. 

The serpentine belt loops around several devices and an idler pulley or belt tensioner allow it to keep in touch with each component and keep the serpentine belt tight. 

The main purpose of the serpentine belt is to drive all the auxiliary functions of the vehicle. If you’d like to know more about the serpentine belt, this article answers common questions about it. 

In case you’re experiencing lifter tick noisealternator noisebad wheel bearing sounddifferential whine noisecatalytic converter noisecar clunking noisecar clicking noise, or bad car ac noise we have got that covered too.

Common Causes of Serpentine Belt Squeal and Other Sounds

If your serpentine belt squeal is there whenever you start your car or turn your wheel, it could be time to give it a look. Serpentine belts do a very important job as explained above and they last from 50,000 miles to 100,000 miles. 

That doesn’t mean it can’t fail sooner due to other reasons, such as improper maintenance or environmental extremes. If the noise is coming from under the hood, it could be a serpentine belt sound, so you need to check it out. 

Before you do, you must understand the causes of serpentine belt noise so you understand what you should look for when you’re looking under the hood. Here are some of the most common causes of serpentine belt squeal: 

The Serpentine Belt Is Worn Out

If you’re dealing with a serpentine belt squeal, it could be because it’s worn out or dry. The serpentine belt may stretch in time, which means it will start to slip and cause a squeaking sound. 

The inside of the serpentine belt has grooves or ribs and those can also wear out over time, which impacts friction and can lead to serpentine belt noise. The edges of the serpentine belt can also wear out or become damaged, thus leading to noise. 

Most car parts go bad over time because they have a finite lifespan. So, the older your car is, the more likely the serpentine belt noise is caused by normal wear and tear. Here’s a short video guide on how to check for wear!

As a rule of thumb, car owners are encouraged to replace the serpentine belt after 75,000 miles. If your serpentine belt is past due and it’s worn or broken as a result, the serpentine belt fix would be to replace it. 

The Serpentine Belt Is Dry

Alternatively, the serpentine belt squeal can be caused by dryness. The belt is in constant friction, so the temperature can make it dry and cause cracks that lead to noise. To make sure, pop the hood and see if the belt has cracks. 

If it does, it means the serpentine belt will snap at any moment, so it needs to be replaced. At that point, there isn’t much you can do about it, but dryness can be prevented with proper maintenance. 

The Serpentine Belt Pulley Is Worn or Misaligned

The serpentine belt itself is not the only thing that can cause a serpentine belt to squeal. Sometimes, the issue is with the pulley system that features the pulley grooves that hold and move the belt. 

Like most car parts, the pulley tensioner may wear out over time, leading to a chirping sound. If that’s the noise you hear, it could mean the pulley grooves are worn out. 

Alternatively, the pulley can be misaligned. If the serpentine belt is cracked, the pulley won’t be as tight, which can lead the belt to slip or snap and lead to squealing. 

It’s not difficult for mechanics to fix a misaligned pulley but it can also be replaced. If you want to check for serpentine belt pulley misalignment, this video may help, but we recommend you get your car checked by a mechanic.

The Serpentine Belt Wasn’t Installed Properly

A serpentine belt installation could be one of the easiest things for mechanics to do. However, the serpentine belt is a high-tension device, so installation requires precision. Professional mechanics are very good at what they do, but sometimes they can make mistakes. 

If you’ve recently replaced your serpentine belt and you’re dealing with a serpentine belt squeal sound, it could mean that it wasn’t installed properly. 

Luckily, it’s very easy to determine if that’s the cause for your serpentine belt squeal. The serpentine belt fix, in this case, would be to go back to your mechanic so they can check it again. 

The Idler Pulley Is Not Tight Enough

The idler pulley is responsible for driving the belt system of your vehicle. It regulates the belts that are connected to the crankshaft, so it allows you to move a bunch of things in the engine, such as the alternator, AC compressor, and more. 

This part needs to be strong and tight enough to hold the serpentine belt at the right tension. If the tension is not right, the belt will slip and cause the serpentine belt squeal that’s been bothering you. 

If you think this might be the problem, take your car to the mechanic and ask them to check the idler pulley. If the serpentine belt has slipped, they will be able to tighten the idler pulley and fix the issue. To give you an idea, here’s how to adjust an idler pulley.

The Serpentine Belt Is Exposed to Coolant

Engine coolant or antifreeze is mixed with water and it helps the engine regulate extreme temperatures, so it’s very important. As the weather changes and the temperature fluctuates, the engine will be pumped with coolant so it reaches an even temperature. 

However, the coolant can cause damage to the serpentine belt if even a little of it comes in contact with it or the drive belt. If there’s a leak, the coolant will drip or blow out of the engine fan, leading to a serpentine belt squeal. 

The serpentine belt fix for this issue is not to wash the coolant off. Why? Because once it comes in contact with the serpentine belt, the damage is immediate. The only solution here would be to replace the serpentine belt entirely. 

The Serpentine Belt Can Be Affected By Weather Conditions

The weather can have a huge effect on the lifespan of the serpentine belt. Cold temperatures can make it brittle, so it can damage more easily. So, if you hear a serpentine belt squeal when the weather is cold but it reduces as the engine warms up, there isn’t a big issue. 

Still, you should get the serpentine belt checked by a mechanic just to be sure there’s nothing wrong. Especially if the squealing sound persists even after the engine is all warmed up. 

Moisture can also lead to a serpentine belt noise, so the early morning dew or heavy fog can make your serpentine belt squeal. If this is the cause of the serpentine belt sound you’re experiencing, it won’t be permanent. It will go away, but if it doesn’t, make sure to check for damage or other issues. 

How to Diagnose a Serpentine Belt Squeal

As explored above, a serpentine belt noise can be caused by many different issues. If the noise is temporary and it only happens when you start the engine, accelerate or turn the wheel, it could mean the serpentine belt is worn, damaged, or loose.  

If the noise is continuous, it could mean the pulley or tensioner system is damaged. To be certain about what’s causing the squeaky serpentine belt, you need to check under the hood and make a diagnosis. 

You can definitely make a diagnosis at home following this guide we’ll provide today. However, if you’re not a professional mechanic, you want to make sure you go to one and get their professional opinion. The diagnostic will give you an idea, but you have to be certain before you do anything. 

Before you get started, make sure you don’t wear jewelry that can get tangled, wear appropriate clothes and keep in mind they might get stained or dirty, and wear safety goggles. 

Diagnosing a Serpentine Belt Squeal

Check the Serpentine Belt for Wear

The first thing you want to do is pop the hood of your car while the engine is off and check your serpentine belt for wear. Make a thorough visual and physical check to see if there are cracks in the rubber, which happens with age as the rubber becomes thinner. 

You also want to look at the edges of the serpentine belt for signs of wear. If you find them, it could mean the belt is misaligned or the pulley is going bad. Look inside the serpentine belt for damaged rubber and check the thickness too. Remember, worn belts are thinner. 

It’s also important that you check to see if any areas of the serpentine belt are shiny or wet. If you find this, it means the serpentine belt has been contaminated with coolant or other chemicals. 

Overall, if you find that the belt is damaged or worn in any way, see if it can be repaired or replaced entirely. If you need a visual guide, this video can help you check the serpentine belt for wear. 

Check the Tensioner

The next thing you want to check is the tensioner and adjust it if necessary. Your serpentine belt must have the right tension. Otherwise, it will become loose and lead to the serpentine belt squeal that has been bothering you. 

The rule of thumb is that if you can push the serpentine belt more than half an inch between the pulleys, you need to tighten it. If you can take the serpentine belt and twist it more than halfway over, then it’s way too loose and you need to adjust immediately. 

Now, tensioners can be manual, hydraulic, or spring-loaded. If your tensioner features an adjustment bolt, you will be able to tighten the belt very easily. Make sure you check the owner’s manual of your vehicle to see how you can tighten the tensioner safely. 

To help you further, here’s a video guide on how to check and adjust the tension of your serpentine belt.

If you find that you can’t tighten the serpentine belt or becomes loose very quickly, it could mean you need to replace the tensioner and the belt. 

Check the Serpentine Belt and Pulley Alignment

Pulley and serpentine belt alignment work in tandem. If the pulley is aligned, the serpentine belt will be aligned as well. If the grooves of the serpentine belt are not aligned, it will lead to a serpentine belt squeal and it can also cause damage to the belt and other components. 

This is why misalignment is always linked to excessive serpentine belt wear or damage. So, it’s important to check the alignment of these components. To do that, you need a reverse belt, laser alignment tool, or straight edge. 

The pulleys should be parallel vertically and horizontally. If they’re not, they’re misaligned, which can be caused by a super tight belt or attachments that are loose or improperly installed. 

One of the easiest ways to check for misalignment is to remove your serpentine belt, flip it 180 degrees, and put it back on. Then, start your car and listen for the serpentine belt squeal. 

If it’s temporarily gone or significantly improves, it means the pulleys are not aligned. If the squeal stays the same, then misalignment is not the issue. Here’s a video guide on how you can use a laser alignment tool to make a diagnosis.

Do the Water Test

After you inspect everything, you should do the water test on your serpentine belt to make sure it’s worn or loose. To do this test, turn on your engine, get it to low idle, and pop the hood. 

Then, take a spray bottle with water and squirt a bit on the ribbed side of the serpentine belt, just ahead of the pulley. Wear protective goggles for this and keep your mouth close because some of the water may be spat back at you. 

After you spray, listen intently. If your serpentine belt is not worn or damaged, the noise won’t change. However, if the serpentine belt squeal increases, it means it’s worn, loose, or both. 

If the serpentine belt squeal quiets down for a moment before returning to normal, it could mean there’s misalignment. It also means the serpentine belt or pulley is worn out. 

Now, if the serpentine belt squeal stays exactly the same after spraying the water, it means that the serpentine belt is not the issue. In that case, the issue could be the motor or auxiliary pump. 

The water test only takes 5 minutes and it will help you confirm whatever conclusions you made after the visual and physical inspection!

How to Stop Serpentine Belt Squeal

Now that you understand what causes a serpentine belt squeal, it’s time to explore the temporary and permanent solutions available!

Use a Belt Dressing Spray

Belt dressing sprays will temporarily quiet your serpentine belt squeal. You just have to spray the ribbed side of the serpentine belt and it will improve friction. The WD-40 Spray is very recommended. When you apply it, make sure you protect your eyes and skin because these sprays can irritate. 

Belt Dressing Spray

Here’s a short video guide on how to spray your serpentine belt safely and effectively.

Keep in mind this is a short-term solution; it will buy you some time, but take your car to the mechanic as soon as you can. 

Use Bar Soap

If your serpentine belt is dirty or contaminated by grease or oil, using a bar of soap can help. The dirt or contaminants will cause it to slip, which is why it could be squealing. 

Just rub the bar soap on the ribbed side of the serpentine belt and it may reduce the noise temporarily. However, you need to find what’s making the serpentine belt and pulley dirty in the first place to deal with the source. 

Align or Tighten the Serpentine Belt

As previously discussed, a loose or a misaligned belt will cause that annoying serpentine belt squeal. So, check the alignment and tautness to make the necessary adjustments. 

If done well, you won’t hear the noise again. If you’re not sure how to do this, take your car to a mechanic so they can do it for you. Keep in mind that if the belt or pulley is worn or damaged they may become loose or misaligned very quickly, which means they need to be replaced. 

Replace the Serpentine Belt

Replacing your serpentine belt is often the best solution. If it has become damaged or worn because it’s very old and it’s no longer in good shape, it makes more sense to replace it. 

However, if the serpentine belt is not too old, you can repair the worn or damaged components. This will save you money, just make sure you go to a professional mechanic. 


The serpentine belt is one of the most important components of your vehicle. If it starts to squeal or make any noise, it’s important to check it out immediately or take it to a mechanic so they can diagnose it. 

There are ways to reduce a serpentine belt squeal in the short term that won’t cost you much money. However, you should have your serpentine belt checked out by a professional as soon as you can. 

If you have the skills to repair or replace the serpentine belt yourself, go for it! Just make sure you get the right replacement and install it properly. If you don’t have the skills, hire someone to do it and make sure they have experience. 

Frequently Asked Questions About Serpentine Belt Noise

Q: Why does your car belt squeal when it rains?

A: If your serpentine belt squeals when it rains it’s because it might be getting wet. Water from your tires can splash on the belt and cause it to slip, leading to a squealing sound. 

The noise should disappear once the serpentine belt gets dry. However, if the noise continues, there could be another issue causing the serpentine belt to squeal. Make a diagnosis and take appropriate action to solve the issue! 

Q: How to fix a squeaky belt with soap?

A: As mentioned before, you can use bar soap to temporarily reduce a serpentine belt squeal. This is a short-term solution and all you have to do is rub the bar soap on the ribbed side of the serpentine belt. It’s not recommended that you do this for long, so make sure you find a permanent solution. 

Q: Is it safe to drive with a squealing belt?

A: It’s safe to drive with a squealing serpentine belt for a few days or a few weeks at most. However, it’s not 100% safe to drive around with a faulty or damaged component. The sooner you get it checked and fixed or replaced, the better. 

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