Belt Squeal -- Why Is My Car Squealing?

Why is my Car Squealing? -- Belt Squeal

When a belt starts to go bad, the squeal it often makes sounds like the worst noise you've ever heard. It's often super loud and high pitched, a squeal that sounds like your engine compartment is crying out in pain. The good news in all this is that the belt is still functional, and the squeal is just a warning that the belt will soon go bad.  In a way, it would be nice if all vehicle maintenance problems were this easy to diagnose. Often, when a car starts having problems, the only warning you get is the maintenance light, which gives no specific information whatsoever as to which part of the car is having problems.The other good news about fixing a failing belt is that it isn't generally very difficult.

Belt squeal is caused by the rubber teeth wearing down and the belt begins to slip.
Belt squeal is caused by the rubber teeth wearing down and the belt begins to slip.

What Makes a Belt Squeal?

When belts begin to wear out, they start to slip. A belt is similar to the gears on a giant clock. It has teeth and is meant to grab hold of a corresponding area on the wheel that turns the belt. Take a look at the picture to the right.  You see how the underside of the belt isn't flat but has little teeth to help it grab hold of the surface it's on.  What happens is that, because the belt is made of rubber, it begins to wear out over time.  Once a belt wears down enough, it begins to slip, meaning that the wheel turning the belt moves but the belt stays in place.  When this happens, you get a pretty loud squeal.  The belt is generally still functional, meaning that it still has some grip, but because of the excess friction and heat generated from the slipping, the belt will wear out very quickly.

Tips for Stopping Belt Squeal

If you don't want to replace your belt just yet but are tired of the horrendous noise coming out of your engine compartment, there are a few things you can do.  One is to take a pad of green Scotchbrite to the wheel that drives your belt and the grooves in it.  Essentially you're buffing and cleaning it of dust and impurities, giving your belt more of a surface to grab hold of.  Another thing you can do is to use spray conditioner for your squealing belts.  The spray to the right is a good example.  This product both quiets squealing belts but also promises to increase overall belt life, which is a good investment for around $5.  If you're having squealing belts and want a more quick fix, I'd recommend the spray.  But you need to be careful because belts will eventually snap if they get too worn out, leaving you stranded somewhere.  Don't neglect real maintenance too long in lieu of the quick fix.

Finding the Right Belt

Not all belts are the same, and different makes and models of cars use different systems for their belts.  Some cars have individual belts, meaning that there's a separate belt for your alternator, your fan, and so forth, whereas other vehicles have a serpentine belt that routes through all of the different systems.  If you have individual belts, you'll have to find out which one is beginning to slip and make the nasty squeal.  Keep in mind that the belt might also be the AC belt, and it might only make the squeal when the AC is on.  That being said however, a good practice is to change out all the belts at the same time (timing belt excluded).  If one of your belts is starting to go bad, chances are that the others are as well.  In fact, if your belts are starting to go bad, it might be a good time for a regular tuneup.  Generally things like belts, spark plugs, and other things involved in a tuneup are changed all at once.  If your belts are starting to squeal, check to see when the last time you had a tuneup was.  If you don't want to get a full tuneup, then you'll have to go down to your autoparts store and order a new belt or belts.

Replacing a Belt

Once you've made up your mind to replace the squealing belt, the best resource available to you about how to change out and replace your squealing belt is to use your vehicle's owners manual. The owners manual will show you the proper way to change the belt for your particular car. If you have a serpentine belt, for example, the owners manual will show you how to most easily attach it to all of the different systems and how to tension it correctly. If you don't have your owners manual, then that makes things a little bit more complicated. You'll have to wing it a bit. The best thing you can do is to talk to the person at the auto parts store when you buy the belt and ask them for tips on how to install that particular belt.  It's generally a pretty simple task.  You have to release the tension on the belt, put on a new belt, and reapply the tension.  Not rocket science.  But since different belt systems vary greatly, it's difficult to give specific advice.

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Comments 25 comments

JohnBarret profile image

JohnBarret 6 years ago

Good informative article a driver must read this.


Benjimester profile image

Benjimester 6 years ago from San Diego, California Author

Thanks John. That's nice of you to say.


Kyle J. K. profile image

Kyle J. K. 6 years ago from San Diego, CA (USA)

Ah, the joys of auto repair. I remember replacing my belt last year.. it's so satisfying when you can diagnose a simple problem like this and fix it on your own. Of course I knew that belts squealed when they began to wear out, but I didn't realize it was because they were slipping on the spinning pulleys. That makes great sense! Very good article for basic auto maintenance!


Benjimester profile image

Benjimester 6 years ago from San Diego, California Author

Gracias amigo. I think you had just about the worst experience possible with a broken belt, because it actually damaged other parts inside your engine compartment. That's just brutal. I almost mentioned that while writing this that belts breaking can do additional damage.


Benjimester profile image

Benjimester 6 years ago from San Diego, California Author

Awesome. Thanks for that video. It was epic. Definitely don't try that at home though :)


Chris 5 years ago

will a new belt still squeal a little or does that mean the tension still isn't right?


Benjimester profile image

Benjimester 5 years ago from San Diego, California Author

New belts shouldn't squeal. The tension is probably off, like you said.


John 5 years ago

Very informativew article! I am definitely bookmarking this site. Thanks again! John


Benjimester profile image

Benjimester 5 years ago from San Diego, California Author

Sweet, thanks man. Glad it helped.


RobertDCrandell profile image

RobertDCrandell 5 years ago

Great information here. Thanks for sharing Ben.


Benjimester profile image

Benjimester 5 years ago from San Diego, California Author

Sure. Thanks for stopping by!


andy 4 years ago

My h2 belt squeals more everytime I push on the gas more I press on the gas more the noice


Benjimester profile image

Benjimester 4 years ago from San Diego, California Author

It's probably time for it to get changed then.


christina 4 years ago

My belt is new and still makes that noise it is loud and people stare lol jokes what can i do.


Benjimester profile image

Benjimester 4 years ago from San Diego, California Author

Hey Christina, it probably just needs to be tightened a bit. Someone should be able to help you with that.


lisa 4 years ago

thank you sooo much!The info you gave was very helpful.


Benjimester profile image

Benjimester 4 years ago from San Diego, California Author

Right on. Thanks very much for saying so.


bobby 4 years ago

very informative. and well written too. Thanks for the article.


Benjimester profile image

Benjimester 4 years ago from San Diego, California Author

Thanks!


Baptiste 4 years ago

I've been a long-time reader of RCS but have never left a cmnemot, until now. Thanks for sharing this gem of a store. I, too, have been looking for graphic tees to fill a certain age gap and these appear to be the ticket. I've flirted with the idea of buying a few Guy Harvey tees but could never bring myself to do it. I can promise you that I'll be in touch with Maria very soon. Thanks again for sharing this.


mike 2 years ago

Not all squeals are the belts fault, bad pulleys or belt tesioner can cause this noise with a new belt


Donna 2 years ago

My car squeals when K first turn on the fan fo defroster and air conditioner any ideas..??


jeremy 2 years ago

my belts are all brand new and i just tightened them a bit more and it still squeals when i turn it on now i did put belt dressing on then after it squealed again but that didn't help at all any suggestions plz help me


Joyce 23 months ago

I have a 2010 Toyota Corolla. I had a brand new belt put on the car because it squealed. It is still squealing. Its seems as though if I turn off the defroster button and fan it will stop. After I have traveled a ways and the car has warmed up it will not do it again until it gets cold again. What else could it be?


nita 21 months ago

My car squeals only does it when its wet and cold when I turn the steering wheel all the way to the right plz help

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