CharlieCole

I have a 1994 Jeep Cherokee Sport 2 door 4.0L I6 manual 5-speed and I have replaced the idler pulley twice. The sound is still present; like a chirping noise at idle. When I give gas, the noise becomes a screaming sound. I noticed today if I spray WD 40 on the back side of the idler pulley it seems to help, but noise gets louder when giving gas. I then sprayed the back side of the AC pulley and the noise completely stopped at idle and returned when giving gas. I did find out that the idler pulley bolt torque spec requires 45lbs using a torque wrench, which I don't have. Before buying the torque wrench, is it possibly the AC pulley or AC clutch causing the screaming noise? Why is the idler pulley still chirping after two brand new pulleys?
I've already replaced the tensioner collar and adjuster bolt, which by the way took 2 weeks to find the correct parts. So I know it's not a loose belt issue.
I'm at a loss at this point and would rather not take it to a shop. Any help would be appreciated.

Billy Bee

I bet your alternator isn't turning as free as it should, or something isn't. When you spray the WD40 you're likely getting it on the belt. Start it up and look for whats not sure as fast as the rest. Use a 1-2 ft length of hose and put one end to your ear and search with the other end for the noise causing component.

- My jeep was screaming like the PS pump was gone. Alternator was frozen.

CurrySoSpicy

Have you spun every pully by hand with the belt off to check for bad bearings?

brielly1

Hold a mechanic's stethoscope to each component. The loudest one is your culprit. Im my case it was the alternator.

investinwaffles

Check if it is the belt or a bearing/pulley.

First - take the belt off and give it a really good cleaning. Second, clean all the pulleys.

With the belt off, spin all the pulleys except the crank/harmonic balancer and check for any grinding noises, play, rubbing, etc.

Put the belt back on, and tighten it to normal tightness (should be barely able to turn the belt 90*).

Start it up and try to identify where the squeaking is coming from. Mine is currently squeaking from the water pump and idler pulleys, and it is because the harmonic balancer is wobbling just barely which throws the belt alignment off. Spray the belt with water to see if the problem goes away, if it stops squeaking when you spray the belt then it's the belt rubbing somewhere. If it goes away when you spray a pulley bearing then it is a pulley causing the issue. Also check the alignment of the belt and see if there is any wobbling and such (water pump pulley seems really prone to causing belt squeak/squeal because of it's design and placement I think)

The pulleys need to be 100% aligned, even a slight misalignment could cause a belt chirp or squeal.


My guess is it is either tension or pully alignment causing the squeak, and same for the squeal but it's hard to diagnose.

Waynerd

I have a Chevy van and for the longest time I could hear a pully that sounded like it had bad bearings. Swore it was the idler pulley until one night the alternator seized. Also on a Cherokee had an AC pulley seize. You need to do as recommended and remove the belt and spin them all by hand. And the issue with your bad idlers, any chance you're over tightening the belt?
Also the pulley on the steering pump has been known to crack and cause chirping. Mine is actually cracked but is quiet.

XJRed96

How old is the drive belt? becuase what you are describing sounds more like a belt noise than anything else. By spraying the WD 40 you are likely getting some over spray on the belt and quieting it down a little bit. Try a new belt, if it doesn't work return it. And when the belt is off to replace it spin all the other bearings. make sure they are smooth and quiet not gravely. maybe pick up a can of brake clean if you dont have one laying around to clean all the pulleys. a quick spray is more than enough, try not to spray to much Inside the alternator.,

cruiser54

This^^

BlueRidgeMark

Bingo. A mechanic's stethoscope will tell you amazing things about your engine. Don't waste time with a bunch of other things to try to figure this out. Get one, use it, and be done.

cruiser54

Under $5 at Hobo Freight. Noggin pokin' time!!!!!

diskman

Check your harmonic balancer. Your XJ is now old enough to drink and chances are that it's the original balancer. It will start seperating and cause the belt to not run true and squeak.

Mine walked back INTO the front cover causing all sorts of havoc..

Shine a light down to the balancer. If you see black rubber strips poking out it's time to replace.

Remove the serp belt and hand turn all the accessories if balancer checks out.

At 23 years old it's probably due to be replaced anyways.

Failing Balancer Pic:


My front cover.. Whoops!

dzywicki

I had something similar when my belt got contaminated with coolant. I cleaned it several times and that still didn't fix it. I then tried "belt dressing". that made it quiet for a few minutes and then the chirping/squealing came back. If you have sprayed WD-40 on the belt then there is no way that belt isn't completely contaminated.
After I ran out of other options, I got a new belt and cleaned every single pulley to get all dirt etc. out of the grooves.
Put the new belt on and has been quiet ever since. I will never use belt dressing again and will never try to wash and reuse a contaminated belt again. Not worth the time or hassle.

BlueRidgeMark

Yep.