I've been told that a wet serpentine belt causes this. Is that true? If not, what else could it be? How can I fix this?

This is a 2004 Chevy Trailblazer (4.2L 6-cyl. engine). I hear the noise every time I start the engine and it usually makes the noise for a little bit while I'm driving it.

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    First, you should add some more information. Which particular engine are we talking about? What do you already know about the problem? Where do you hear the noise when you look under the hood?
    – Bob Cross
    Mar 9, 2011 at 16:56
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    Can you be more specific? Under what circumstances do you hear the squeal, e.g., constantly, only when you rev the engine, etc.? Can it be reliably reproduced, or is it intermittent? Mar 9, 2011 at 16:57
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    possible duplicate fix squeaky belt
    – Patrick
    Mar 9, 2011 at 20:34
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    In fact, if you dump a glass of water on a suspected squeaking belt, it can go away for a few seconds. This can help you diagnose your problem.
    – JeremyP
    Mar 13, 2011 at 1:12
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    here's something to try... when the car is on and the high pitched noise seems to go away, push the A/C button to turn off the A/C. Does the noise come back and stay permanently on? If yes, then it's your A/C pump clutch bearing and this is a very known "feature" of a TB.
    – DXM
    Jun 29, 2011 at 1:52

2 Answers 2


In most cases this is the Serpentine belt. As the belts get old they will relax a little and the loose belt will squeal when the car idles at first then all the time as the belt continues to age. Water will cause the belt to make noise as well. Your options are to buy a new belt and put it on the car, or to tighten the belt a little so it squeaks a little less. There is a wheel that the belt twists around that you can adjust when replacing an old belt or when tuning the older belt. Honestly if you have the time and the Manual/Confidence to replace the belt, I would go that route. Belts are not that expensive, and depending on the condition of the old belt. it may be the better option.


Belts are cheap. I'm of the opinion that if a belt does anything to make you even take a second look at it you might as well replace it... i.e. if there's any question as to its integrity, swap it out with a new one and properly tension it. The first time you switch one out it'll take you a little time, but after you've done it once you'll usually be able to switch them out pretty quickly. After you've replaced the belt then you can proceed with troubleshooting from there if the noise remains.

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