Belt Squealing Mystery.

John Theis

LVC Member
Oct 29, 2017
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05 3.9 ls here. Belt started squealing when warm once in i while. So i changed the belt. nothing. Replaced idler pulley. nothing.

Now it does it everyday. Sound is coming from the passenger side and usually does it when its warm. Not on the first startup of the day at least. High pitched and loud. Not a constant squeal but more "squeek squeek squeek". It will go away if i spray water on the idler pulley only. tried spraying the belt on the drivers side and on the other pulleys with no help. I have tried silicone spray, wd-40, and penetrating oil.

Any ideas would be great. Its driving me bonkers.
Also tried putting more and less tension on tension pulley with a breaker bar. Didn't do much.
You replaced the noisy pulley?
Is the tensioner moving back and forth when this is happening? If so, take a close look at the damper pulley. Is there any wobble?
I did replace the pulley. Tensioner doesn’t move at all. May be a very small bit of wobble on the dampener. I sprayed down the dampener pulley last night with wd40. No luck there
I almost hate to mention it, but any spray of WD-40 that got on a belt surface (or pulley surface) would almost certainly guarantee slipping.

Ya I was thinking about that on the wd40 too. Didn’t change a thing and I sprayed it every where
I did the three Hail Mary with mine. New belt, new idler pulley, and new tensioner. Purrs like a sleepy kitten now. I feel your pain, the "squeek" was killing me too.
Got a video up. Just I little quirt of water on the dampener shuts it right up. ...

That's very similar to the squeaks that my 06 would make in cold weather. I think I see the problem. Looking at your damper, the rubber ring that separates the inner and outer parts of the damper appears to be migrating to the back of the damper. It should be about even with the front surface of the damper, but it looks like it is recessed. The back of the damper is very close to the timing cover, and the rubber that has moved back is probably rubbing on the cover (mine did) and making the sound.
You know I think you got it! I sprayed some wd40 behind the dampener and it was quiet. How did you fix that?
Replace the damper. If you don't, eventually the pulley part will separate from the inner part and may do a lot of damage when it comes flying off.

The new OEM ones are very expensive, and the aftermarket ones are pretty high too (plus apparently not too reliable). I found an LS in a local junkyard that still had one and removed it (about $30). It was an 03, but they are all the same for 00 to 06. I would avoid 05 and 06 though, since the problem ones seem to be on those.

You can send yours out to be rebuilt.
Note that you should replace the front seal at the same time, and you are supposed to replace the bolt (but many don't).
Where do you send it to get rebuilt and is it at least half the cost of a new one?

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