I recently installed a Continental Accessory drive kit on my W251 (M272 engine).
Install went swimmingly and i finished up by giving the engine a good power wash although I tried not spray directly on the bearings and electrical connectors.
Well the idler pulley has a squeak and its driving me nuts. I narrowed it down to that particular part by applying ATF to it.
Im looking at my old pulley and its completely sealed with no cover or gasket to remove. Im not sure if the power wash had anything to do with it bcos I cant see how enough water could get in the bearing to affect it. The part number to the pulley is a2722021419 and I torqued it down correctly.

Would someone please give me advice on how to resolve this squeaking sound?
Thank you in advance

 

Look at the back of the old pulley. It might appear completely sealed off, but you should see the backside of the bearing. The metal cover is a dust cover. Take a small flat blade screwdriver, pry the dust cover off. The bearing will now be exposed. Use some wheel bearing grease and repack the bearing. then press the metal dust cover back on. I've done a few idler and tensioner pulleys this way and it saves it for a second life.

 

Thank you so very much for that spot of advice!
i went right out to the old pulley to see what you were refering to but i didnt see it. The whole middle section looks like 1 solid piece. I ran a metal pic along it but didnt catch any lip. There is also a grooved channel which runs right down the middle of part where the belt rides. Perhaps this is where the pulley is actually sealed? I ran my pick along it and it seems to be metal and not an adhesive.

 

Am I seeing both sides of the pulley in pics 1 and 3? Assume I am -
Yes, that is different than the usual idler. It does look like perhaps the pulley splits in half, if so, it would need to be an awfully tight press fit, or adhesive; otherwise, stresses under operating conditions would eventually separate the halves.

If you're adventurous, try to split the halves with some force on the old one. See if it separates.

 

So I was indeed feeling adventurous this morning and decided to sacrifice my old bearing for science.
I took my dremmel and went to work. I cut at various spots to see what I could gleam but I ended up simply removing the top of where the bearing resided.



Here you can see there is the outer housing and the inner bearing which seems to be pressed together.
I cut some more to remove the ball bearings from one side. Then I started to dissect the line where the belt rides and as I was clamping it down it actually separated just a hair from the clamping force on the other side.




This is a photo of the top half removed.





So I figured I could get the inner bearing out with a simple vice/press but it proved VERY difficult.
When I examined it a bit closer I realized that the stamps in the metal around the inner bearing were holding it securely to the outer housing.
That being said there is no way to get to the inner bearing to service it without utterly destroying it.

But I also noticed that there was almost no way for water/dirt to really penetrate that inner bearing either.
Even if completely submerged I don't see hardly any water getting in. So if anything this examination gave me confidence that, baring a manufacturer's defect, my new bearing is good.
But that begs the question: What is the true nature of the squeaking sound I have been hearing.
Could it be some slight slippage between the bolt which secures the bearing the the engine and the bearing itself?
I can't imagine that as the bearing spins very freely. But perhaps the ID of the bearing is slightly larger than spec for the bolt which holds it.
I don't suspect my torque wrench is off either.

Anyway I haven't heard the squeaking over the 2 times I have started the engine but if it comes back I may remove the pulley to clean it out (and the bolt) off with fine sand paper.
Then perhaps reinstall it with a thin coat of gasket maker to ensure a proper hold and prevent future water/dirt ingress.

 

Very interesting! In all the years I've "regreased" idler and tensioner pulleys I've never seen a design like this one. Learned something because of your good work!

One observation I've made of these that I could service - they tend to be woefully underpacked with grease on the ones where I could remove the dust cover.

Best,

 

Just just to update this thread. I used RTV to try to seal the space between the bolt and the center of the bearing (thinking that water ingress might have been the cause of my issues) and i even torqued the bolt down to 35 as opposed to 25nM but i still got the squeaking sound. The next day i applied a few drops ATF on the bearing's seam. I did this with the engine off to prevent the ATF from flinging anywhere else as i wanted to be sure where the sound was coming from. Sure enough the squeak immediately ceased when i started the engine.

So i convinced myself that l, somehow, had a defective bearing. Went out and ordered an INA bearing from the parts store and installed it. Started up the engine and heard a faint squeak for a few seconds but it quickly went away and all was silent. Looking at the replaced idler again i noticed a sticky residue on the track where the belt rides. Could be from the belt not agreeing with the brake cleaner i sprayed trying to get the engine bay clean. i took 000 steel wool and skimmed the back of the belt to remove any sticky residue that may have left behind. I proved, to myself at least, that it wasnt the belt sqeaking but the bearing itself. The squeaky idler was also an INA brand and identical to the new one installed. Not sure if i can ask for a warranty replacement since it was part of the kit but im happy that the squeaking is gone.