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I have a squeaky belt in my car that is driving me crazy! Is there a general fix or belt treatment product I can buy to silence a squeaky belt? If belts are squeaky, does that mean time for replacement instead?

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up vote 11 down vote accepted

The main cause of a squeaky belt is the rubber has stretched causing a reduction in friction allowing the slippage to occur.

There are two ways to solve the problem:

  1. Tighten the belt by using the appropriate tensioning technique (generally loosening the bolt that hold the pulleys in position, realigning the now-loosened pulley & retightening the bolt)
  2. Putting belt dressing on the belt
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Assuming the belt has correct tension and still squeaks it's rare to find anything more than a short term solution, other than replacing it.

However, if you really want to give something a try, most industrial suppliers can sell you a can of "belt grip" compound, which is sprayed onto the contact surfaces of the belt and/or pulleys while they're rotating (as slowly as practical). Note that you will get some of this stuff thrown onto you while you're spraying it, so dress appropriately.

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Would the belt grip work if the squealing is caused by getting coolant on the belt? – endolith Nov 9 '15 at 15:22

If you don't have time to deal with it you can try the belt dressing, but I do not recommend it. I've had it happen plenty of times and it has been caused by improper tensioning (too loose). Find out what the proper deflection should be using your shop manual (a must have for proper diy maintenance) and set it. You can purchase a gage, but in my experience it is do-able with trial and error. If that doesn't correct it, replace the belt.

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It's worth noting that if this is a serpentine belt with an automatic tensioner, it cannot be adjusted. In this situation, it's possible that the spring in the automatic tensioner is loose and the tensioner itself needs to be replaced. – S_Niles Mar 8 '11 at 7:49

If you have more than one belt in your car, you might need to determine which of the belts is squeaking. The quick and easy way to pinpoint the right belt is to pour a class of water on the belt with the engine idling. You'll probably have to be fairly accurate, since the belts are often close together. The sound should go away for a few seconds.

Once you know which one is at fault, see if there is any way to manually tighten it, or if it has an automatic (non-adjustable) tensioner. Of course, if the belt is old, cracked, or frayed you really need to replace it. Tighten the manual tensioner a few turns (if so equiped) to see if that fixes the issue, but don't overtighten it. When pressing on the longest length of belt (between pulleys) it should move only 1/2 to 1 inch, but I need more info about your car to be more specfic.

It's possible that the belt tensioner is broken and causing the problem, not the belt. If you put a new belt on, and it still squeaks (with the auto tensioner), I would suspect that the tensioner is bad.

The 'fix in a bottle' solutions are only a band aid, and won't last for long, except your wallet will be $5 lighter. Sorry...

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A very quick shot of a water displacement spray will do the trick. CRC or WD40. Not much. If you use belt will sing to you as it's sticky. Before doing anything... take a wooden do well and, with the engine running, place the end of the dowel against your idler pulley. If so equipped...making sure not to get it unto moving parts. Put your ear to the other end of the dowel. If you Hear a high pitched whine...change the idler bearing or assembly. If you hear any low pitch, listen to the water pump... then the power steering pump...then the AC pump...if none are whining...spray the belts very lightly. A belt will dry-rot...and will sing. A small amount of water displacement fluid will quiet down your problem...but change your belts when you can. W.A.L. Chattanooga///

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If you are talking about a squeaky alternator or steering belt you might need to retension it, if that does not work a replacement might be in order.

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