iNfiNkC

My car was making a rattling sound when the car ran, like clack/clack. I first thought it was my PS pump, changed that and the sound was still there. Did some more research and the Assy. belt tensioner was a major cause of engine noises.

Thanks PureMS for the new tensioner(best price i could find)

For the replacement:

Tools used:
Gear wrench with socket adapter
17mm socket
10mm allen socket
ratcheting 1/4 wrench for hose clamps.
<img src="http://img135.imageshack.us/img135/3634/toolslk4.jpg">

Remove the passenger side Bi pipe.

Relieve the belt tension with a 17mm socket and remove the belt.
<img src="http://img355.imageshack.us/img355/6595/17mmtensioneroa5.jpg">

Remove the screw holding the ac fan, then turn the fan and it will unlatch from the support.
Move the fan out of the way.
<img src="http://img355.imageshack.us/img355/2456/fanscrewjy9.jpg">

<img src="http://img149.imageshack.us/img149/2584/fanun1.jpg">

Remove the old tensioner with a 10mm allen.

<img src="http://img135.imageshack.us/img135/4874/10mmnx7.jpg">

Pull the tensioner out.

Old and new tensioner:

<img src="http://img355.imageshack.us/img355/599/oldandnewwd2.jpg">

Now install the new tensioner, put the belt back on, install the bi pipe back in, engine covers.

Done.

Took me 1 hr to do the job, hardest part was getting the belt back on over the altenator pulley.

s481::ASPstg3

Was it a constant, almost rotational clacking sound? ... sounding kind of like a old mercedes diesel sound?

iNfiNkC

sounded like this<ul><li><a href="http://www.youtube.com/watch?v=OjTR8yRRaqs">http://www.youtube.com/watch?v=OjTR8yRRaqs</a</li></ul>

HIS4

Is that the tool to lock it in place? Is it the special VAG tool or just something you had lying around.

iNfiNkC

its a pin that came with the new tensioner makes it easier to install instead of using a screwdriver

2quattros

Thanks for the replies

The part I'm confused about is why it only happens when I put the car in drive. The minute the revs climb above 1k it stops. But, at a stop with my foot on the brakes, it rattles a lot and only after the engine warms up to operating temps

I did do a visual inspection of the belt tensioner when the engine was running and it does not seem to be bouncing like it would if the spring was broken.

I'll check it again when I get home.

iNfiNkC

its not that the tension goes bad, its the pulley bearing that goes south.

scottr20ae

Thanks for the writeup, it really helped give me the confidence to get this done.

I pulled my old one off, and the pulley bearing is clearly going bad, the new one turns a lot easier. The old one will not spin, it will only turn as long as you turn it, as soon as you let go, it stops.

Tips for future reader/installers.
1.I bought a stethascope from O'Reillys, and put it on the tensioner(from the bottom) before doing the job, and it sounded a good bit louder than other components I put it on, so I chose to replace it.

2.Use the 17mm wrench to release the tension on the belt, once you turn it clockwise. This was mentioned, but not in enough detail for me(2.7t rook.)

3.Be sure to find a belt diagram(with AC) and really pay attention to where the belt is routed.
*I mistakenly skipped the tensioner(after a very long day) and proceded to doubt that I put the tensioner in the right place(not to mention I had to get the pin back in to keep the tensioner untensioned(for lack of a better word.)) I pulled it off, and put it on numerous times before I went to bed, and got a good night of sleep, before I realized my belt routing error. Once I did that, and got a mirror to see that the whole for the dimple on the back of the tensioner is a good bit larger than the dimple(I had it right the night before, but it moved too much in the hole for me.)

I say all that to say this, Thanks to iNfiNkC for the write-up, and be sure to watch the details of putting the tensioner on, and routing the belt.

Oh, and if it makes you(not iNfiNkC) feel any better, I had an APR Bi-pipe, so it took me a lot longer than an hour. How long, I won't say, but a few bolts were lost, and much sweat and frustration was spent.