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

).
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.