Originally Posted by Bigclubs

"Don't Worry" is sometimes not the best advise, the squeeling is telling you something should be checked. I have a 96 that the belt would squeel when turning on the AC, squeel during very damp weather or placing the heat setting to front window defrost, but not when I put it on heat or vent.
I changed belts twice, tightened the belt accounting for stretching. My jeep mechanic friend told me to us AC Delco and not those cross cut style belts. Use the full straight rib style belt. I changed to this type of belt and the noise went away for quite a while except for really damp rainy days. It would squeel at start up until the belt dried out. When it came back after a year, i also looked at the alternator, AC compressor, water pump etc. My guage would drop some when the squeel appeared, so I was looking at replacing the alternator, figuring the bearings were going south.

One day the squeel turned to a metal grind noise and my battery light came on so I fugured the alternater was shot.
I made it to Sears Auto where I work part time for extra cash to have one of my buddies check the alternator. He opened the hood, I started the engine and Power Steering Pump blew, spraying fluid all over the engine.
The squeeling has been my Pump bearings all this time.

So take a look, tighten the belt again and check all the pulleys and bearings the belt comes in contact with. XJ surpentine belts seem to need to be tight!!

Originally Posted by GovernorKC

I had a very similar problem. when the Jeep was cold and turned on defrost i would get a squeal. after engine would warm up or i got to about 50mph the squeal would stop.

then one day i lost all power and car died and wouldnt start. had it towed in battery and alternator replaced.

problem was fixed, no squealing for about a week. now the squeal is back. any ideas? could something me causing the alternator to go bad?

Originally Posted by xj2fsj

In my case the telltale sign that the alternator was the problem was the build-up of black belt 'dust' around the alt. pulley and on the housing directly around the pulley. That was a pretty strong indicator that the alternator shaft was turning slower than the belt was moving and so the belt was sliding over the pulley causing friction and disintegrating the belt.

My battery and cables are new So I expect that Troths post was accurate. Based on this I can assume that tightening the belt would mask the symptomatic squealing issue temporarily by increasing the grip on the pulley to compensate for the drag but will not actually fix the problem. It's pretty obvious what the eventual result of this will be.

I went to the salvage yard, pulled a used dakota alternator, had it tested at a local parts place, replaced my alternator with it, retightened the same belt to the original tension and the problem was completely gone. I then replaced my belt with a new AC Delco. I meant to have my original tested but returned it as a core during a brain fart.

Coincidentally, my wifes mazda protege was having an identical (not exactly, her overload was caused by a combination of headlights, rear defrost, and heater) problem. Same fix, same result.

Originally Posted by xj2fsj

270?!? Wowie! Where did you get it and who makes it and how much was it!

Originally Posted by scott t

With the start of all of this cold weather my 01 Cherokee Sport has picked up a squeal in the front end. I replaced my serpentine belt the beginning of December, so the belt is fairly new. The squeal happens for a short time when I start the Jeep, but starts again when I run the heat, and also during acceleration. Also, tonight (not sure if this problem is related) the voltmeter reading dropped to minus 5 (9) and the check gauges light came on. This makes me think that my alternator is bad, but I'm not sure if that would account for the squeal.

This just has me stumped. Any input appreciated

I have the 4.0 L straight six and everything else is stock

Thanks

Scott