Alternator or AC compressor noise.

[loke]

I have lately noticed that when I turned the AC on my voltage dropped significantly (on the gauge). I was expecting it to be my alternator going out and didn't pay too much attention to it, but Sunday I started to hear a very loud noise from the engine compartment. Having a broken bolt in the exhaust manifold I thought it was the manifold vibrating and again I didn't think to much about it.
Then yesterday while driving to work I noticed that my voltage was very low and when I left work the engine died on me. I was in traffic and restarted a couple of times and managed to get in to a parking lot. When I popped the hood I saw that the belt was broken.
I replaced the belt and started again and the noise was worse then ever. I suspect either the alternator or the AC compressor to have no bearings left.

Any ideas as of how to find out which it is? I tried to spin the pulleys and they spin freely with no noise. I don't really want to let it run for a long time with the head under the hood (I would expect to get decapitated by the belt if it breaks again http://s4.images.proboards.com/wink.gif ).
This is an '85 with 2.5 liter engine. No mods to the engine.

[Saudade]

Does it make noise with the AC off?

[loke]

Yeah, I just started the engine up, but I didn't turn on the AC.

[Saudade]

Then check the waterpump and any idlers as well. If the all seem to spin freely, then make sure the belt is tight. New belts can loosen up quite a bit with only a few minutes running.

With a new belt on, it's unlikely to break too fast. You can run it and listen in from the side to determine where it's the loudest.

[loke]

Ok, I guess I could have been a little more specific. All pulleys spun freely (except the one attached to the engine ;) ). And the sound definately seems to come from either the compressor or the alternator.:dunno:

[frankenjeep]

i too have the same sound and dont know which its comming form

99xj sport

[90xj06]

usually if the if you twist the ac pulley does it fell like its pulsating.

[loke]

Pulled the belt off last night and when spinning the pulleys I found out it was the alternator. Sounded like there was a handful of gravel in there and it would actually lock up.
After putting the new alternator in tonight I should be good to go again.

[barillms]

My evil squeal was happening every start, for 3-4 secs. Then while running once I kicked the AC on.

I ended up being my belt was TOO LOOSE. I dressed the belt, and I thought it was ok... but I ended up having to tighten it up pretty good, more than I expected. Now it doesn't squeal, but take belt off and hand-check all the pulleys to make sure they spin freely.

Your compressor clutch could be going. There is a trick to fixing the compressor on here. It's simply removal of a washer behind the clutch face. Check it out.