"squealing sound" from engine compartment (espec. when A/C is on)
 

I have a 99 cherokee XJ with the 4.0 6 cyl. It makes a "squealing" sound from the engine area (from the pulley area) especially when its raining or when the Air Conditioning is turned on..... I installed a new belt, tried to adjust it (but doesnt seem to help, maybee the belt tensioner is bad?) and the A/C compresor is new (about 1 1/2-2 years old) so I don't think its the A/C compresor, it seems to come from where the belt tensioner is or power steering pump area......What do I need to do to fix this?? Its so irritating......

Phil :w00t:

it is the A/C compressor its the bearings, mine does the same thing, if you dont wanna replace them buy some spray to spray on it and it will go away for a while

Mine does the same thing. Where do you spray the lube to make it stop the noise?

on the compressor where it turns the belt

You mean behind the pulley? I have some lithium grease, will that work?

also if the belt is old it may be glazed, check the tension on the belt and adjust is more then 1/2 of play when you press on it. but mine occationally chirps engaging.

Don't spray anything on a serpintine belt, I would just replace it, if you sprayed anything on it and for what ever reason on a 4.0 the tighter the better (to a point) with new belt.

yeah its the pully, mine has a new belt onit and it still squeels

i thought they all do that

Sounds like the Belt needs tightened up a touch

Mine is also doing it. If I shut the A/C off for just a sec and turn it back on it stops.

it sounds more like a belt than anything else change it first

mine does it. my belt is new and tight. my a/c is off at startup and it does it almost everytime.

like i said everybody its the pully on the compressor, ill bet all of yall if you go spray somethin on the pully like WD-40 or anything like that then start up your XJ it wil do it for a second then stop for a while, ill put money on it

Long answer to your thread.
Well let me put my 2 cents in on this.
I get tired of hearing it's always the AC pulley or bearings. I also have been fighting with the squeeling during damp weather, putting the vent controls on window defrost, or using the AC. I also replaced the AC unit with a used one which seemed to stop the sound for a little while, but the noise came back.
I wrote in other threads, my friend who works as a mechanic at the jeep dealer told me to get rid of the serpentine belt with the newer diagonal cuts across the belt and replace with an AC Delco type with straight grooves. These other belts are prone to make the belt squeel. I did replace the belt and the squeel did dimenish for a while, but still came back during rainy days and using the defroster setting. One day the squeel turned into metalic grinding, which turned on my battery light. I figured it was the Alternator Bearings grinding. I had a spare used Alternater and took it to AutoZone to check out weather it was good or not. Alt. OK. Since I work part time at Sears Auto Center, and had to work that night, took it with me. While pulling it in a bay to have another installer look at to verify the grinding noise was fom the alternater, the POWER Steering pump went out. Sprayed fluid all over the engine. We replaced the pump resevior and pulley with a new one. WOW the squeeling noise went away and I am able to use the defroster and AC without any more noise. There have been a few threads about the powder steering pumps being a problem and creating the squeeling noise as the bearings go bad and slow down the speed of the belt. Of course the engine is still trying to spin the belt at a high speed and the belt squeels. Look at your power steering unit before condeming the AC unit.

x2 on check the power steering, i know mines going, and anytime i go through a big puddle my steering gets really choppy and the belt starts screaming for a few minutes then all goes back to normal

Since we are all putting forth our 2 cents here's mine . Go to Harbour Freight or your local auto parts store and get a stethascope about $5 or use a piece of hose, start the motor and go from pully to pully until you find the offending part then remove it and replace it. If the noise occurs only when the AC is on its probably the bearing in the clutch on the way out .

There is a few things that will make the belt squeal. I dont have a sqeal anymore. Used to sound like a pig being molested. Here's what my issue was and how I fied it. Replaced the old belt with a dayco unit that had cross cuts in it. It helps Keep the belt cooler. They arent as strong as a solid ribbing all around but a cooler belt is key.

My idler pulley bearing was on its way out. Took it out and replaced the bearings in it with some bearings that I had laying around that fit. Im cheap but like to do things right. did some light sand blasting to the remaining pulley's only to roughen them up a bit, Helps the belt seat on the pulley properly and have "traction". The sand blasting didnt remove much but tok away any glazing on the pulley from rust and from sitting for a year as a secondary vehicle.

Tightened the belt up as tight as I could. Usually if you tighten a belt up too much your asking for trouble. You put too much pressure on the bearings and they will fail. First two bearings that will usually fail are the alternator and the water pump. Saying that, being that the belt is new, its gonna stretch a little and keeping it tight will help condition the pulley's and the belt to each other. Any contaminates on the belt will introduce a sqeal. It adds Lubrication and it breaks down the belts composition.

Only time I spray anything on a belt is to figure out where the issue lies. For example, Is it the idles pulley making noise, or is the clutch in the a/c pump failing. Or is it something like the water pump is leaking through the weep hole on its way out and introducing an oily substance to the belt causing it to slip.

Anything that you add to a belt to make it stop squealing will be temporary. A?C clutches can be replaced. Pulleys can be dressed to allow the belt to seat better.

90 percent of the belts that I have had to diagnose has been something along those lines. on anything that has a belt tensioner that is spring loaded its always been the spring or corrosion.

IMHO, Fix the cause and not mask it. Its fustrating to have to revisit the same issue over and over when all that energy could have been used more efficiently to diagnose and correct the base problem.

If your low on cash and need temp fix. They sell a belt dressing product that actually reconditions the belt to an extent. An old belt gets hard and glazed. Usually accompanied by the ribs of the belt cracking.

squeaky problems I have a 98 cherokee and it did the same exact thing if u would look closely when u turn your jeep on then flip the ac on then look where the fan clutch pulley and u will see the belt jump when u throttle it so what I did was to thighten up the belt some more. I spoke with a mechanic that worked with a jeep dealer and he said that cherokee r notorious for belt sqealing. worked for me and I hope it works for u all

Thanks bigclub. I thought it did not come from the AC side of the engine. I thought it was the power steering pump, but wasn't sure. Thanks for the second opinion.