Why Do my Engine Belts Squeal?

Squeaking BeltHave your friends nicknamed your car screeches?  Do you park in front of a different apartment building so when you start your car up in the morning and it makes an obnoxious squeaking noise your neighbors won’t know it’s your car?  Having a vehicle with squeaking or squealing engine belts can be embarrassing and annoying.  The terrible noise is also an indication that your engine belt will likely not last much longer and could leave you stranded and your car broken down.

The belt or belts on your engine are used to transfer the rotational energy of your vehicle’s engine to turn any accessories you also want to be powered by your engine.  Some of those accessories are essential for your engine to continue to run like the alternator or the water pump.  Some of the accessories are just for convenience like the AC compressor or power steering pump.  Either way, the belts in your vehicle are important.  Vehicles today either have multiple accessory belts where smaller belts are used and a single belt will only run 1 or 2 accessories with 3 or 4 total belts running off the crank pulley.  This is a safe combination because if 1 belt breaks, often the others will not.  Hopefully you will be able to get your vehicle to safe place without being stranded.  The other belt setup is called a serpentine belt meaning one larger belt runs all the accessories and runs in a serpentine route between and around all the pulleys.  In both cases the belt has to be at the proper tension to work properly.  If the belt is too tight it will create extra resistance in your motor, wear out pulley bearings too fast and could cause the belt to stretch or break quickly.  On the other hand, if the belt is too loose it can slip off or slide on the pulley not transfer the proper power to the accessory.

Your engine belts make a screech or squeal noise usually because the rubber belt is slipping on the metal pulley and just like your tires spinning on the road, this causes noise.  The belt may be slipping due to improper tension or because it simply has gotten old and the surface has become glazed, cracked or brittle.

If you believe your belt may be old or in need of replacement, consider doing the job yourself.  Replacement belts are usually relatively inexpensive and easily accessible on the front of your engine.  Check your vehicle’s manual for instructions on how often to change your engine accessory belt or belts.

Squealing BeltIf you believe your belt may just be improperly tensioned you can try to adjust the tension yourself.  Most serpentine or single belt systems use an automatic belt tensioner which is just an idler pulley on a spring loaded arm.  The spring tension causes torque on the arm of the idler pulley which pushes on the belt and should keep it at the proper tension.  If your belt tensioner is damaged or the spring has lost its tension replacing it may help restore the proper tension to the belt.  If your belt does not have an automatic belt tensioner, it likely is tensioned by adjusting a non-spring loaded idler pulley or by adjusting one of the accessories itself.  You can look for an adjustment slot and screw on your idler pulley or accessory.  Loosen any nuts or bolts holding the pulley or accessory in place, adjust it until the belt is at the desire tension then re-tighten the bolts.  This is often best done with the help of a friend.  To know when you’re at the proper tension you can use a belt tension measuring tool, or tighten it to the approximate tension of the other belts on your engine.  There is a relatively wide range of acceptable tensions on your accessory belts so check your owner’s manual for the proper range.

Don’t let your vehicle’s squealing or screeching continue to be an embarrassment to you.  Have the confidence to change or tension your belts today!

Pictures provided by: forum.miata.net and www.2carpros.com

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32 responses to “Why Do my Engine Belts Squeal?

    1. Franky-

      The belt may be slipping due to improper tension. You may attempt to adjust the tension yourself, most serpentines use an automatic belt tensioner which is just an idler pulley on a spring loaded arm. The spring tension causes torque on the arm of the idler pulley that will push on the belt to keep it at the proper tension. If your belt tensioner is damaged or the spring has lost its tension then you may need to replace it to restore the proper tension. If your belt does not have an automatic belt tensioner, it probably is tensioned by adjusting a non-spring loaded idler pulley or by adjusting one of the accessories itself. You can look for an adjustment slot and screw on your idler pulley or accessory. Loosen any nuts or bolts holding the pulley or accessory in place, adjust it until the belt is at the desire tension then re-tighten the bolts. This is often best done with two people. To know when you’re at the proper tension you can use a belt tension measuring tool, or tighten it to the approximate tension of the other belts on your engine. There is a relatively wide range of acceptable tensions on your accessory belts so be sure to check your owner’s manual for the proper range.

      -BDP

  1. i had my belt replaced 2 years ago on my 2001 Ford Taures & the sqeek (songs like birds squeking) came back ….i was told it was the tension pully (the larger one) so my friend replaced it & it still sqeeks!It does’nt squeek when i rev up the engine though…..so can it be the belt actually doing this like you said or could it be another pully? Can pullys also cause the sqeek?Another mechanic told me he thought it was my alternater ……my alternater is working fine but the belt does go around that also…….what do you think it is?

    1. Theresa-

      Thanks for your question about your 01 Taurus belts. It sounds like you are on the right track to finding your problem. Along with the tensioner, you may have also needed a new belt. The squeaking noise you are hearing is from the belt slipping on a pulley so as it is slipping and squeaking it is also heating up where it slips and could be glazed or become brittle at that point. Even with a new tensioner these glazed areas of the belt could still make the squeaking noise you are hearing. A new belt along with your new tensioner would solve this problem.

      The squeak could come from a component like your alternator. If the alternator bearings are wearing out it could be causing extra drag on the belt and cause it to slip at low RPM’s, causing the noise you are hearing. If you take the belt off and spin the alternator pulley by hand you should be able to feel bad bearings dragging and it won’t be easy to spin. If you can easily spin the alternator pulley by hand while the belt is off, then that probably isn’t your problem.

      -BDP

  2. I have a 2002 Chevy Avalanche and its squealing. When I put some lubrication on the belt, it stops for a min but then it will start again. And I’m certainly not going to put anymore lubrication on it seeing is how that’s a very bad idea. From what I just typed, can I be for sure that it’s just the belt or should I still be cautious about the idoler? Thanks 🙂

    1. Cody-

      Most likely you are correct that the belt simply needs to be replaced. However, we also recommend checking that the tension is set correctly; you can check the owners manual for the proper range that the tension should be set at.

      We hope this helps!

      -BDP

  3. my 07 explorer sport trac squeals pretty bad and terrible in the rain. I believe it’s the tension on the belt. I do see some rubber on the the pulleys, should i clean that and adjust the tension? I thought it was the alternator bearings because the squealing seems to be triggered by the AC. but reading here seems that it is just not enough tension on the belt, how do i know if i have enough or too much tension?

    1. Michael-

      Most serpentine or single belt systems use an automatic belt tensioner which is just an idler pulley on a spring loaded arm. The spring tension causes torque on the arm of the idler pulley which pushes on the belt and should keep it at the proper tension. If your belt tensioner is damaged or the spring has lost its tension replacing it may help restore the proper tension to the belt. If your belt does not have an automatic belt tensioner, it likely is tensioned by adjusting a non-spring loaded idler pulley or by adjusting one of the accessories itself. You can look for an adjustment slot and screw on your idler pulley or accessory. Loosen any nuts or bolts holding the pulley or accessory in place, adjust it until the belt is at the desire tension then re-tighten the bolts. This is often best done with the help of a friend. To know when you’re at the proper tension you can use a belt tension measuring tool, or tighten it to the approximate tension of the other belts on your engine. There is a relatively wide range of acceptable tensions on your accessory belts so check your owner’s manual for the proper range.

      Thank You!

      -BDP

      1. I have a relatively annoying squeek coming from what I think is my idler pulley on my chevy s10 with the 4.3 ac serpentine, alternator was shot, replaced that, tensioner chipped replaced that, still squeeking, serpentine belt replaced and went through about 4 idler pulleys, and squeek still is there other pulleys have louder and dimmer squeeks, grease in the bearings seemed to make it worse, I have no other troubleshooting possibilities and out of options please I need a second opinion.

        1. Jeremy-

          Thanks for your question about your S-10. It sounds like you’ve done just about all you can to stop this squeak! The first thing we would recommend doing is taking the belt back off and making sure all the pulleys in your system spin freely by hand. You will feel resistance in your power steering and water pump but they pulley should still turn easily, smoothly and not wobble. If you find one that is sticky or wobbly, replace that component.

          The other thing you can try is using belt conditioner. You may have to find an older independent parts store, but many will sell a spray on lubricant for belts to help quite them down. This conditioner will make your belt softer and run more easily on the pulleys hopefully quieting it down.

          -BDP

  4. I have a 1984 Buick Riviera. The air condition compressor’s bearing froze so we decided to cut the belt for the compressor. We put new belts on the engine, but now the belt squeal. Do you know how to get this to stop without adding a new compressor? I decided not to use the air conditioner and do not want to put one on. Thanks for your help

    1. Cialella,

      Thanks for your question about your 1984 Buick. It is possible that a company makes an idler pulley you can bolt on in place of the air conditioner. If that isn’t available, the other option is to find a smaller belt that can bypass the air conditioner pulley while still covering the other accesories. Since this would be a custom application you would have to find an auto parts store that will help you try a few different belts to find the right length.

  5. Hello.! I will be much glad if u answer a question that if the belt is tightened much than the normal,can it cause engine to make unsmooth acceleration or like it is pulling some heavy thing?

    1. Malik,

      There shouldn’t be any way your engine belts being over-tightened could affect acceleration of your car to the point that you would notice it. If you are having acceleration problems try checking your regular maintenance items like your spark plugs, air filter and fuel filter. Also, consider using BlueDevl Fuel System Cleaner (available here: http://store.gobdp.com/fuel-system-cleaner-00202/) to make sure your fuel system is clean and your fuel injectors a firing properly.

  6. Hello, I just got home from work. While leaving, I noticed a clunking noise while turning in reverse. Then while driving home I heard a high pitch whining noise coming from the engine? I have an 03 explorer. It stopped while in overdrive but made the noise in 3rd? (Auto trans) Previous owner said he replaced the Alternator maybe half a year ago. I just changed the Oil and transmission fluid about a week ago.

    1. Rod-

      Sometimes if problems happen right after some maintenance was completed, they can be related to whatever maintenance was just done. In your case, we would suggest checking the transmission fluid level and making sure on your receipt that the correct type of transmission fluid was put in your Explorer. Since the whining noise goes away in overdrive but is there in third, it seems to make sense that the noise has to do with your transmission.

      The clunking noise you heard while turning in reverse could be a suspension problem, or a problem with one of your CV joints. For a quick read on CV joint problems, check out our article about that here: https://www.gobdp.com/blog/steering-wheel-noise/.

      Thank You!

      -BDP

  7. hi. wat would be the problem if my belt is not tight enof .orr if i over tightened the belt , could be a trouble??

    1. Rachid-

      Yes, if the belt is not properly tensioned you could experience issues when driving the vehicle. We recommend checking your owners manual on how to properly tension the belt.

      Thank You!

      -BDP

  8. I have a friend’s van and it was making a real loud squealing noise I’m assuming from a serpentine belt I sprayed lubricant spray around pulleys to try and stop the squeal , well next thing I know the belt slips off , it is a 91 Dodge Caravan. With me spraying that did that cause the belt to slip off or was it just a matter of time that the belt slip off ?

    1. Tammy-

      Thanks for your question about your Caravan. If the belt slipped off with the lubricant it probably was on its way off within a few miles anyway. Now that the belt is off, we would recommend replacing it with a new belt as they are relatively inexpensive and you have to do the work to get the new one on anyway. With a new belt you should be fine leaving the lubricant on the pulleys.

      -BDP

  9. when i start my car the rpms and speedometer gauges fly up and i hear a loud screech in the serpentine belt if i revv it up it stops but starts again a little later ive replaced the belt and disconnected the ac compressor due to it freezing up im not sure if its the tensioner what do u think?

    1. Brandon-

      If you’ve already replaced the belt then it seems most likely that the tensioner has gone bad as well. The other possibility is that your AC compressor is still causing problems. We’re not quite sure what you mean when you say you disconnected the compressor but if the belt is still running over the pulley it could still be causing problems. To totally bypass it, you would need to remove the compressor and install an idler pulley or install a shorter belt if the routing made sense.

      Thank You!

      -BDP

  10. Helo my hyundai getz 2003 keeps making a noise on start up of the engine it sounds like its coming from the fanbelt but im not entirely sure thats the problem any help please ?

    1. Chad-

      The noise you are hearing on start up may be due to the belt slipping off of the drive pulley. This could be from improper tension or the belt has simply cracked or become brittle with age. If you believe the belt is improperly tensioned, you can try adjusting the tension yourself. If the belt seems old, a replacement belt would be the best cure.

      Thank you!

      -BDP

  11. I have an ’88 Chevy Cheyenne. It has an obnoxious squeal. I have replaced the belt, replaced the tensioner on it & it still squeals. Someone suggested rubbing bar soap on the belt and when I do that it instantly stops the noise but eventually comes back. Help!

    1. Dylan,

      Thanks for your question about your Cheyenne. Since you’ve gotten the noise to go away using the bar soap trick, you know you’ve got your problem pinpointed. If a new belt and tensioner haven’t solved your problem you can try checking the alignment of the pulleys the belt runs on. Make sure all the accessories the belt runs over are securely attached to the block and can’t move at all. Also try removing the belt and checking the pulleys of all the accessories to make sure they don’t wobble and turn smoothly. It is possible a bad bearing in one of your accessories is actually causing your belt noise.

  12. I have an 2001 Taurus and every time the belt gets wet from either antifreeze or cleaning the engine it squeals like a stuck pig. Nothing stops it either. I have to change the dang thing every time. Why is that? Belt can be almost new but once it gets wet it’s done for.

    1. Dan,

      It’s not unusual for belts to squeal when they get wet due to the type of rubber they’re made out of and the high tension they are at. Most belts will quiet down once they dry out if you give it a few days or a long drive. If you have to put a new belt on again you may consider getting some belt dressing, it’s a lubricant most auto parts stores sell in a spray can. Not only will it help your belt last longer and stay soft it should help repel the water and keep your belt from squealing when it gets wet.

  13. hey guys. I just changed all the 3 belts In my Accent car. but when ever I take a turn , it squeaks very loud. what could be the problem. please advice

    1. Sudhir,

      Thanks for your question about your Accent. First, the problem may be that your belts are not properly tensioned. When you turn your steering wheel, your power steering pump puts resistance on the belt and if it’s too loose the belt will slip and squeal. You can check your owner’s manual for the proper tension or stop by your local dealership. If your belts are properly tensioned then the problem could be you have a clog in your power steering system or your power steering pump is starting to fail. To check for a clog, you could try and flush your power steering system. If that doesn’t quiet things down then you’re probably in the market for a new pump.

  14. Hi, I’ve just bought a Ford Fiesta 2003 and just started driving it properly… At first there were no noises but now I’ve noticed that when we are stationary at traffic lights or pulling up on the drive at home, there’s a vibrating squeaky sound which sounds like its coming from under the bonnet. Is it the belt?

    1. Chloe,

      Thanks for your question about your Ford Fiesta. Based on your description of the noise and vibration it does sound like either an engine belt is loose, or one of your accessories is starting to go bad. If you pull the belt off and can easily spin all the pulleys by hand, then it is most likely just time for a new belt and maybe a new belt tensioner. If the pulley on one accessory is hard to turn it may be in indication that the bearings in that component are going bad and will soon need to be replaced.

      Thanks again for your question!
      -BD Auto Pro

  15. I have a 2007 Jeep Liberty. It was making a squealing noise when I would step on the gas. We got a new belt and a new water pump and the noise stopped…..until I took it on the freeway and it was worse than before. It got so loud that you can hear it from inside a house if I drive by. The noise would come and go but when it did start, it would happen every 11 seconds. Of course when I take it home to have my dad take a look at it, the noise stops.

    Is this normal when getting a new belt? Just it getting broken in or is the tension most likely wrong? My dad thinks I’m overreacting

    1. Karolina,

      The noise you’re experiencing is not normal of new belts. It could be an indication that the tension is wrong, but the fact that it’s rhythmic (every 11 seconds) makes us think you might also have another accessory going bad. If you follow the procedure in the article about removing the belt and checking the different pulleys for resistance, that should reveal where the problem is. if nothing seems wrong it may also be the tensioner needing to be replaced as well.

      Thanks again for your question!
      -BD Auto Pro

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