Idler pulley gone bad?

**Raus** · 12-29-2008 05:44 PM

Hey guys, this hasn't been my week. First my front lip got torn off, ran over and destroyed, now lots of noise (grinding/rattling vibration) started coming from the accessory belt area. Today I took off the belt tensioner and noticed quite a bit of play and noise in the bearing so I figured that was the culprit.

I bought a new tensioner and accessory belt but before I replaced them I checked all the pulleys for play and noise. The only pulley that had some play was the idler pulley, the one in the middle that the belt loops around under the tensioner pulley, am I correct that this is the idler pulley?

I just got finished changing the tensioner and belt and the noise is still there

, anyone know approx. how much this pulley costs and what tool is needed to change it? And it looks like the front end has to go into the service position to change it, correct? PITA

**Boosted3.0** · 12-29-2008 06:24 PM

Not sure about the 1.8 but the fans had to come off to change mine on the 3.0. Not the whole front end.

**dirtybrd** · 12-29-2008 06:27 PM

If a pulley isn't running something like a water pump or alternator then it's an idler pulley. Are you refering to the pulley just left and between the alt. and A/C compressor? Another way to make sure that noise is acc. belt related, is to start the car with the belt off. If the noise is gone then the problem lies there, if not you need to look behind the timing cover.

**zz2h33** · 12-29-2008 06:27 PM

when was your TB and associated pulley's/water pump done? Are you sure the noise isnt coming from in there? this is a common sign one of the TB pulleys is about to go, which means get it fixed ASAP.

**Raus** · 12-29-2008 09:17 PM

Originally Posted by dirtybrd

Are you refering to the pulley just left and between the alt. and A/C compressor? Another way to make sure that noise is acc. belt related, is to start the car with the belt off. If the noise is gone then the problem lies there, if not you need to look behind the timing cover.

Yup, the pulley to the left of the AC comp pulley and directly beside the crank pulley. Felt a bit play while all the others had no play and spun smoothly. Made no difference whther the AC comp was on or off.
I'll be sure to run the car without the belt before I buy a replacement pulley, it's possible that it's the TBelt tensioner but I had the Tbelt and updated tensioner done ~35K ago.

Just went for a drive after putting the stock bumper back on (after 3 years

) and the noise is gone at idle for now, but I know it'll come back of course.

Boosted3.0, I was referring to the service position where you unbolt the front end and slide it forward a couple of inches to have room for working in the front of the engine.

**Raus** · 01-02-2009 12:50 PM

It turns out to be the small roller under the timing belt tensioner...it's completely shot. I'll replace the timing belt again while I'm in there since it might have been getting worn out on the broken roller.

**dirtybrd** · 01-02-2009 12:53 PM

Glad you found it before things got real bad for you.

**moses0324** · 01-02-2009 02:52 PM

i had problems similar to what you are explaining...they changed belts, pulleys, the tensioner...it ended up being the water pump

good luck with the fixes!!!

**Raus** · 01-03-2009 02:12 PM

Originally Posted by dirtybrd

Glad you found it before things got real bad for you.

It would have been soon, I got with a magnet ball bearings and the races from that roller which ended up under the crank sprocket.

I'm almost done, I have the torque spec for the tensioner roller (27Nm = 20 ft.lbs.)
dirtybrd do you or anyone else have the torque specs for:

-the two bolts on the tensioner
-the small roller on the tensioner (I took it off the new one because I thought it would make it easier to put the belt on)
-the 4 bolts for the cranskshaft pulley

**dirtybrd** · 01-03-2009 02:51 PM

Finger tight then about 1/8 of a turn, you can use a little loctite if you like.

**Smiley** · 01-04-2009 02:05 AM

IM getting a bit of a noise too..im not sure from where though..

Do you have a video or soundclip or anything by any chance? If not, ill record a better video of "my noise" and maybe you can compare it

**Raus** · 01-04-2009 02:18 PM

I don't have an actual soundclip, buit I just went through like 30 recordings on youtube and this is the closest to what I had. Mine had a little rattle and squeal on top of this as well.

http://www.youtube.com/watch?v=RHsRi...eature=related

As was recommended on this thread and by an Audi mechancic when I was buying parts, run the car without the serpentine belt to make sure the noise isn't coming from behind the timing cover, then you can start to pinpoint it.

**dirtybrd** · 01-04-2009 02:39 PM

Originally Posted by GtiRSmiley

IM getting a bit of a noise too..im not sure from where though..

Do you have a video or soundclip or anything by any chance? If not, ill record a better video of "my noise" and maybe you can compare it

Another way to make sure that noise is acc. belt related, is to start the car with the belt off. If the noise is gone then the problem lies there, if not you need to look behind the timing cover.

**Raus** · 01-05-2009 02:30 PM

I'm having a problem. Everything went fine, all marks lined up perfectly and the car runs smooth but the tensioner keeps moving.

I set the tensioner roller in place with an 8mm allen key between the roller tab and tensioner but when the car runs for a couple of minutes that space shrinks down to ~3mm. Am I putting too much pre-tension on the eccentric adjuster? I basically have it to where it was pointing before. Should I back off a bit on the eccentric adjuster?

**b6_will** · 08-14-2011 03:35 PM

Hey Raus, did you ever figure out your problem? maybe you did, its been such a long time since your problems occurred. I'm having this similar problem....I replaced the timing belt/water pump/tensioner roller/eccentric adjuster. but my tensioner is also moving down. it goes all the way down. It was perfectly fine the first week, then after a week, my car began to shake and vibrate while in idle and if I stopped at a red light but ran fine during higher speeds, thats when I saw that my adjuster was all the way down.

Im really stuck and don't know what it can be. Thanks in advanced.

**CaRtharsis** · 08-14-2011 07:35 PM

Originally Posted by dirtybrd

Finger tight then about 1/8 of a turn, you can use a little loctite if you like.

Are socket head Stainless bolts suitable for the crank pulley?

Also I noticed tonight when installing the timing belt that one of the pins on the plate the swivels the eccentric bolt for the cam tensioner has sheared off. Should i replace the entire tensioner even though I am able to correctly position it for the 8mm spacing and torque the nut?