Why Does my Engine Belt Squeal?


engine 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 noise when driving or a squealing engine belt can be embarrassing and annoying.  Besides being annoying, a squealing engine belt also is a sign that the belt won’t last much longer and could leave you stranded.

Most cars today have a single belt that drives the accessories on the motor.  Things like your alternator, air conditioning compressor and power steering pump are all considered accessories to your engine since they don’t help transfer power to the wheels, but do help run other systems in your car.  

That single engine belt is called the serpentine or drive belt.  This belt is different from your timing belt because if it breaks it won’t do any immediate damage to your engine or car.  If this belt breaks, your alternator will no longer charge your battery causing the battery light to come on in your car.  Also, your power steering pump will no longer be pumping so your steering wheel will be very difficult to turn.  If your water pump is driven by the serpentine belt then your engine will also quickly start to overheat.  If you notice these symptoms together, shut your car off immediately and coast to a safe place.

As with any belt-driven system the tension of the belt on the pulleys is a critical factor.  If the tension is too tight it can put excess stress on the accessory bearings and the belt causing the belt to stretch and fail prematurely.  If the tension is too low, the belt will wobble and won’t have enough friction to drive the pulleys it’s running on.  If this is the case, the engine belt will slip on the pulley causing the annoying squealing noise you hate.

In most newer cars, the engine belt tension is created by an auto belt tensioner.  The auto belt tensioner is a spring loaded arm with a pulley on the end.  Once the belt is fitted over the pulley the spring pressure on the arm puts the correct amount of tension on the belt for everything to run smoothly and quietly.  If your engine belt seems loose, squeaks, or wobbles or flaps while your engine is running it’s possible the tensioner either has a worn out bearing or the spring has lost its ability to create the proper tension.  In most cases, the best next step is installing a new tensioner to create the proper tension on the belt.  In this case, it’s often best to replace the engine belt at this time in case the old belt has stretched and because the belt is a relatively inexpensive part.  You may even consider doing this job yourself as it can be done with simple hand tools on most cars and only requires removing 1 or 2 bolts.

Another possible cause of engine belt noise would be if you have a failing accessory that is causing extra drag on the belt or has a wobbling pulley.  If you suspect this is the problem, try removing the engine belt and spinning the accessory pulleys by hand.  If you can feel play in the pulley, either wobbling or motion in and out, it may indicate a bad bearing and be the cause the noise.  Also, if you feel the pulley has excess resistance, meaning it won’t spin easily by hand, it could indicate an internal failure in the accessory.  If this is the case, you probably will also notice the squeal or squeak when that accessory is taxed.  This would be after startup for the alternator, when turning the wheels for the power steering pump or when the AC turns on for your air conditioning compressor.

The last cause of a squealing engine belt is simply an old belt.  The rubber the belt is made out of wears out over time, can become glazed or even cracked which can all cause noise.  If your engine belt looks shiny on the ribbed side or has cracks in the ribs, consider replacing it to see if that quiets things down.

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engine_belt.jpg – By NexTser – Licensed by Getty Images – Original Link


BlueDevil Products can be found on Amazon.com or at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, and other major auto parts retailers.

32 responses to "Why Does my Engine Belt Squeal?"


  1. franky on December 15, 2014 at 11:57 am

    i changed my belt to a new one and it made the noise even worse

    • BlueDevil Pro on December 16, 2014 at 9:29 am


      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.


  2. Theresa on March 12, 2015 at 5:19 pm

    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?

    • BlueDevil Pro on March 25, 2015 at 9:03 am


      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.


  3. Cody on March 30, 2015 at 5:20 pm

    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 🙂

    • BlueDevil Pro on April 2, 2015 at 8:58 am


      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!


  4. Michael Barnum on May 12, 2015 at 11:42 am

    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?

    • BlueDevil Pro on May 13, 2015 at 12:08 pm


      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!


      • Jeremy furgus on May 23, 2015 at 2:08 pm

        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.

        • BlueDevil Pro on May 28, 2015 at 2:14 pm


          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.


  5. Cialella on May 31, 2015 at 2:41 pm

    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

    • BlueDevil Pro on June 11, 2015 at 1:51 am


      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.

  6. Malik on June 4, 2015 at 1:27 pm

    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?

    • BlueDevil Pro on June 16, 2015 at 6:47 pm


      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.

  7. Rod on June 24, 2015 at 6:19 am

    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.

    • BlueDevil Pro on July 6, 2015 at 1:39 pm


      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://gobdp.com/blog/steering-wheel-noise/.

      Thank You!


  8. Rachid Pauletta on June 29, 2015 at 1:14 pm

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

    • BlueDevil Pro on June 29, 2015 at 2:39 pm


      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!


  9. Tammy McKenzie on July 24, 2015 at 10:14 pm

    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 ?

    • BlueDevil Pro on August 10, 2015 at 10:34 am


      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.


  10. brandon on July 25, 2015 at 7:25 am

    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?

    • BlueDevil Pro on August 10, 2015 at 10:34 am


      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!


  11. chad on August 3, 2015 at 5:09 am

    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 ?

    • BlueDevil Pro on August 7, 2015 at 11:16 am


      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!


  12. Dylan on August 8, 2015 at 9:37 am

    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!

    • BlueDevil Pro on August 17, 2015 at 6:57 pm


      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.

  13. Dan on August 13, 2015 at 6:26 am

    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.

    • BlueDevil Pro on August 21, 2015 at 12:09 pm


      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.

  14. Sudhir on August 15, 2015 at 12:54 pm

    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

    • BlueDevil Pro on August 21, 2015 at 1:27 pm


      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.

  15. Chloe on August 27, 2015 at 1:35 pm

    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?

    • BlueDevil Pro on September 10, 2015 at 4:59 pm


      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

  16. Karolina on September 14, 2015 at 9:50 am

    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

    • BlueDevil Pro on September 30, 2015 at 7:25 pm


      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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