Hi all - so I've searched around for answers / advice, a lot of which I've followed, but have yet to be able to resolve the chirp chirp chirp of my serpentine belt (or related drive-belted component). THis has been an off and on issue for 3-4 YEARS now. Here's the situation and what I've done so far:

New belt - 1 month ago (poly belt - had Gatorback on prior - also chirped) Chirp coming from center of the serpentine belt area.
Increases with increased RPMs.
Goes away for a minute when I put a bit of water on the belt (so it's not the distributor).
I've noted is also a bit variable (doesn't necessarily chirp "in rhythm")

No noticeable "grinding" or rough spinning of any pulleys
Idler pulley / tensioner replaced about a year ago
New water pump / t-stat (no coolant leaks) - 4 months ago
New alternator - 1 month ago

Looking at the alignment front to rear, there doesn't seem to be anything totally out of whack. There is a very slight "wobble" to the fan pulley (the water pump is fairly new), but the chirp isn't in time with that wobble. I've read a bit about the harmonic balancer chirping, but would this noise go away when water is put on the belt itself?

Any troubleshooting advice etc is certainly appreciated.

 

Tighten the belt? The 4.0 belt is supposed to be crazy tight. Very little deflection when tightened properly. I suggest giving it a slight tightening.

 

Thanks - should have mentioned the belt is pretty tight. It deflects about 1/4 to 1/2" at the tensioner. I worry somewhat about over-tightening (2.5L, for what it's worth).

 

I had a squeak for about a month that I could not figure out. Changed the belt twice, idlers etc... Then one day I was on the freeway and heard this terrible noise and my temp shot up fast. Lost the outer ring on the damper. Changed the damper and now no more noises. So look good at the damper for sure. Oh and mine did get quiet with water which is why I tried 2 different belts.

Max

 

Thanks - I think this will be the next place I look. How tough was it to replace the damper / harmonic balancer? I've looked a bit into it, but haven't dug in as of yet. Are there any diagnostics you know of to narrow it down to the damper?

 

My harmonic balancer makes a rhythmic noise too, incombination with the serpentine belt which is slowly getting chewed up by the balancer. There is a rubber strip sandwiched in between the inner and outer metal rings on the balancer and that strip is split.

To replace it, you'll need a puller tool that you can rent from Autozone. A new balancer can be as cheap as 35-40 bucks and a new belt is about 20 bucks. Not too hard to replace.

I would have done mine already if I had the $ to do so..but this fool is broke. :/

 

If the bearings on all the pullys are fine pull the belt and wash it with dish soap and see if that helps. I had a few that caused the same problem an after washing the belt the problem was gone.

 

The more I read up on the Harmonic Balancer issues, the more I'm inclined to think that's the issue.

Is there a way to check it without pulling it off? Is there anything to look for that would indicate it starting to separate (aside from it rubbing ont eh front of the timing chain cover, which I don't think is occurring). I'll try to get in there with a flashlight tonight if I can.

 

If you crawl under the front center, you will see the balancer right there. Mine appears to wobble a bit when it is spinning and I can see that from the side on top while the engine is idling.

It may be possible that the balancer is fine on your jeep, but perhaps not in alignment with the rest of the pulleys..

On mine, the rubber strip is coming out of the pulley and is easily seen.

 

Just as an aside (since I'm guessing the belt is not your problem), this business about the amount of deflection that the belt is supposed to have is almost always wrong. The factory service manual will specify an actual belt tension value in lbs or Kg that you can measure and set with a $15 belt tension gauge.

The first time I did a cooling overhaul on mine, I ignored what the FSM said and set mine according to the deflection guidance I read on this message board. The belt squealed like a ****. I went and picked up a Krikit tension gauge at NAPA and set it again according to the specs, and it had been nowhere near tight enough.

For the life of me I can't understand why people will spend $150 on a good torque wrench to make sure all their bolts are torqued exactly to spec and then ignore a $15 tool that would properly set their belt tension, especially considering everything a failed belt would affect.

 

This is funny.

A buddy of mine just called to tell me about a weird chirping noise on his 2000 XJ. Balancer was fine.

The oil pan gasket was smooshed out just enough to contact the balancer and he said it sounded like a bird..Worth a look.

 

I had belt squeeling also. Turned out the belt needed to be tightened even though it already seemed pretty damn tight.

 

Not sure how I didn't stumble on this in the past, but the initial diagnosis is certainly pointing towards the harmonic balancer. I took a look tonight and the outer portion is about 1/8" offset from the inner part (offset towards the radiator fan - not the timing cover, thankfully). So I'm guessing this is causing a misalignment and the resultant chirping.

Ordered a Dayco "powerbond" balancer from CARiD - it was the only place I could find a non-Dorman balancer for the 2.5L, as I've heard about fit issues with those. The Dayco was $10 less with shipping too. Gonna shoot for putting it in after the holiday weekend and read up on removal and install in the meantime. Hope I can squeeze a few short drives out of it beforehand - pre-turkey day surf tomorrow!