Squeeling under the hood.

There is a high pitched squealing from under the hood of my '90 Chev half ton. What is the best way to tell what it is? I believe it may be the water pump but don't want to replace it without knowing for sure. I'm
going to replace the serp belt, since it needed it anyway, and take it from there. Any tips?
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Does it happen with the serp belt off? If yes, it isn't the water pump. If no, then you know it's a belt-driven assembly.
Does it happen with the A/C on? With the A/C off? That should help you with a bad bearing on the A/C pump.
Using a screw driver as a stethoscope, can you hear it coming from the alternator? Put it on the alternator, not the bracket - less chance you will hear the steering pump if it is that. If yes, bingo. If no, next step.
Using a screw driver as a stethoscope, can you hear it coming from the steering pump? Put it on the pump, not the bracket - less chance you will hear the alternator if it is that. If yes, bingo. If no, next step.
Using a screw driver as a stethoscope, can you hear it coming from the belt tensioner? If yes, bingo. If no, next step.
Using a screw driver as a stethoscope, can you hear it coming from the water pump housing? I would do it last, because looking at my 1990 GMC Jimmy I think there would be quite a bit of "background" noise from this part.
Just be careful around the rotating parts. Hope this helped.
GMC Gremlin

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The water pump is also driven by the serpentine belt.

half
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wrote:

The water pump makes a squelling sound that goes away after a short while of run time after a cold start. Made me think it was the belt but some water on the belt will make a belt noise go away thus narrowing it down. YOU"LL GET WET with the fan running LOL -- Best Regards Gordie
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Rob, Read my post a weeeeeee bit more carefully. Or... finish reading it. One or the other. Please.
GMC Gremlin

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hehe I don't think that would cause a squeek though... lol
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Chev
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I removed the belt to see if everything turned freely. Everything did and upon replacing the belt (with the same one)the noise is now gone, for now. I'll keep ya posted.
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