I have a 99 cherokee xj and there is a squeal/squeak coming from one of my pullies(i think).

When I get it up to about 10 mph it starts to go away, but as soon as i let off the gas(even if its over 10) it starts squeaking, and no matter how fast im going when I accelerate it starts again. I know its not the belt cause when I put dressing on it the squeak stays!

Any help???

There should be one belt and a TENSIONER and also an IDLER.
Both the tensioner and the idler have the same bearing in them that is in some roller skates! These bearings wear out after a while and make noise before coming apart.
It is always best to replace BOTH at the same time.
This is a common question about squeaking. Almost all the time it is one or both of the above.. Though sometimes it is other... such as bolts coming loose on the mounting of the alternator or A/C compressor and causing a squeal..
If these bearings havn't been replaced in a few years then it is time anyway. This is a cheap repair anyone can do with a small amount of tools.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Ok, so i know the "tensioner"(15mm bolt adjustment), is the idler different? Where exactly is this located? The only other pullies I see are the AC/PS/WP etc...

I'm not 100% sure on your jeep, but the tensioner is the Power Steering pump and the idler is over by the AC with just a bold going through it...
Could be wrong, but the last cherokee I worked on was like that...

There were 3 different diagrams on alldata for my make/year. The one that was correct shows that the idler/tensioner is the same pully, and its located under the PS pump pully.

I hope thats where its comin from cause that would be a super cheap easy fix!

Loosen/remove the belt. It should feel super smooth. If it is rough and has a little play... it needs replacing anyways!
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Depending on the layout of the A/C, Power steering, possible air pump and alternator there may not be a need for a seperate idler in the system. Some have them and others don't.
I'm guessing you are lucky that only one is there to wear out.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

A common source of belt noise on the 4.0l is a separating crankshaft damper pulley. Check the spacing on the rear of the crank pulley to the timing cover. Normal space is about 1/16" to 1/8". Any more or less indicates a damper that is coming loose, the resulting misalignment causes noise. Sometimes the rubber is seen to be squeezing out between the inner hub and outer ring.

Hope this helps!

The harmonic balancer coming apart seems to be a problem with the 4.0 in Ford engines also.
The ones I've seen come apart where the rubber meets the outside ring on the balancer.
The ring begins to slip and gets looser and looser until it finally spins into the timing cover or smokes the rubber and alarms the owner. Once the belt is off the ring simply falls off the main part of the balancer.
I have seen it blamed on the amount of HP needed to supply the needs of the belt driven appliances. I appears to be rare, indeed, but is happening.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" /> <img src="/forums/images/graemlins/pfft.gif" alt="" />

Seeing that it's over 10 years old, and probably has over 100k miles on the clock, it's actually pretty likely it's bad.

I think you can get a new one in the aftermarket, besides sourcing one at the dealer.

I probably changed 2 or 3 a month at the dealership.

Probably a good idea to install a new timing cover seal if you have to change it, it comes out without removing the cover.