water pump or AC compressor?

I have a '99 Montana w/ 147,000 miles and have a belt squeak/squeal issue. I replaced the belt and tensioner in the last six months, however, in the last two weeks, I have a new sound issue. It is coming from the front side of the serpentine belt and I have narrowed it down to either the water pump pully or the AC compressor (one on top of the other in the belt flow of things). It is a squeak squeak sound w/o the AC on, but turn it on and more of a growl or rumble sound. It is not noticeable at highway speed and you can hear it on initial acceleration or just revving the engine. The AC cools great, however, both are original parts. Humm, which is it? Hopefully the water pump, since I have done those and this one looks pretty easy, however, anyone have sounds emitted when either are going bad? My past experience on water pumps is they leak, not make noise when they go bad and AC compressors, the same, leak oil/grease and lose freon, not make noise (unless the belt is loose). I did note a tiny amount of antifreeze on the radiator hose near the water pump and noticable antifreeze stains under the hood (flung by water pump). This, however, was a tiny amount and it is not even wet anymore, but no drip drip, so I'm leaning towards the water pump, but am I too optimistic? Input appreciated!!

The waterpump is cheap and easy enough. 20 bucks for the pump (AutoZone), an hour or two to replace. Since it's leaking, might as well do it.


Sounds more like the A/C clutch is going out, though. The A/C compressor is really 2 parts - the R134a pump, and the clutch mechanism. The pump might be fine, might just be the clutch (that the belt rides on) that's going bad.

Guess what? Neither was bad, it was the cursed belt. I had put a new Dayco belt on, which spilt w/in 4 months, got a free replacement but a few months later the new one was squeaking. Put my factory one back on last week (had in in the van as a backup) and squeak got worse. Had the mechanic look at it to see which pully was bad, but it was actually the belt. Now I have a new Napa belt (manufactured by Gates according to the mechanic) and my pride is a little sore, I should have just bought a new belt when I first heard the sound to rule it out!! My inital hunch was correct, but didn't think my spare (which never squealed) would do the same thing. Huh, live and learn. From now on its Gates or Goodyear Gatorbacks (put one on my Jeep) only. If the water pump loses any fluid it is outta there, looks like it is at $24.XX at Advanced and Autozone, so pretty minimal expense there as well.

Update, this actually turned out to be a bad harmonic balancer after everything was said and done. I did replace the water pump, was going to do the radiator hoses as well but could not get to the upper radiator hose clamp (the one that actually hooks into the radiator). Anyone entirely remove the upper hose? If so, how did you get to the clamp (dern engineers!).

I've reused the clamps in the past but if you can't get them at your local parts store the dealer should have them. You can always go with one from the hardware store.

Up here they can be bought in a package with a hose replacement kit.

...this actually turned out to be a bad harmonic balancer after everything was said and done.
Thanks for signaling this. There have been several such cases across the GM cars forums and it is always after everything ihas been looked at . For the record, are there any visual telltale symptoms, signs or indications or photos of the bad balancer that would help others pinpoint this issue in the future ? ... ?

Guess what? Neither was bad, it was the cursed belt. I had put a new Dayco belt on, which spilt w/in 4 months, got a free replacement but a few months later the new one was squeaking...From now on its Gates or Goodyear Gatorbacks (put one on my Jeep) only.I know that you've figured out it was a different problem, but I want to second going with a Gatorback belt. I had been going with the stocking brand sold by Advanced Auto, which is Dayco or their identical but less warranty sub-brand of Drive-Rite. I was always dealing with squeaky belts either on start up, cold days, or in wet weather. Switching to the Gatorback solved that issue. Unfortunately Advanced Auto doesn't stock the Gatorbacks locally in the correct size, but Auto Zone does normally. It costs a few bucks more, but the belt has lasted longer as well so it's been worth it.

I've reused the clamps in the past but if you can't get them at your local parts store the dealer should have them. You can always go with one from the hardware store.

Up here they can be bought in a package with a hose replacement kit.

Let me try phrasing this a little differently. I cannot get to the upper radiator hose clamp where it hooks directly into the radiator by typical means (pliers or channel locks). The remaining three clamps (both lower radiator hose clamps and where it goes into the block on the upper) look pretty accessible, but that one has me perplexed. Anyone have any hints?

As far as a visual on the hb, the only indication it was out of wack was the fact that the belt was half on and half off of it, indicating that it had moved away from the block. I would put the belt back on and in moments, it was back halfway off, the pulley was out of alignment with the others.