Replaced my SC pulley this weekend (went with a 15% Craven), as well as taking the time to change the plugs and belt (40K miles, I know, shoulda done that MONTHS ago...).

Anyway, after a very smooth extraction of the old pulley, then putting it all together again, we turned the engine over, and heard a NASTY racket coming from the belt area. Immediately saw that the belt had also walked on the new pulley, moving about 1.5 grooves toward the engine block. That's not good. Replaced the belt with another one, and at first this did not happen again, but sure enough, after starting the engine once more, the same things were back again.

Replaced the pulley with another Craven 15%, on the off chance that this was somehow not aligned. Same problem. Took the pulley off, made sure that it was seated all the way back, and tried again; no dice. Checked the belt once more, just to make sure, but didn't see anything. Let me tell you, after this, I can tell you EXACTLY what size bolts are in which locations, what with taking them out and putting them back in so many times. The only thing we could come up with was that the tensioner was the culprit.

In the end, we decided to try the old belt. Initially, that same noise was heard, but since I was already over an hour late getting home, I didn't want to **** off the WifeUnit TOO much, so I decided to risk it, and hit the road. Under 5 miles later, the noise was gone.

When I called the dealer, they told me that the belt I was using was the wrong size. However, I know that this is the same belt that others in the club have used when changing out the pulley. The sleeve says that it's a NAPA #060539.

So, my question is, has anyone else heard of this happening? Do I have a tensioner that is going out on me, or do I really have an incorrect size belt somehow? Or, is it possible that the stiffer belt is really the cause, and I would actually be just fine letting it sort itself out after a couple miles?

 

I know I probably sound like the king of tensioner and belt problems, but I recently suffered this anomaly so if I can help anybody save the misery of a trip on a tow truck I'm gonna' try...

I did a m7 16% pulley with a Dinan belt. Belt shredded after ~3K miles and I truly believe it was a self destructive kinda' thing. Belt tension was on the tight side which enforced the destruction/wearing out of my tensioner.

The 539 series belt is the correct 15-17% pulley upgrade option.

Check the idler pulley on the tensioner and see how much slop it has. If that wobbles around your tensioner needs replacement.

Where did your tensioner position end up post install (in or out of spec on the guide)?

After my first belt replacement the racket would dissipate after ~5-10 minutes of running but start up again on a true cold start (sitting overnight). You could watch the tensioner hop around trying to handle its own wear and the increased belt tension (vs. the normal smooth oscillation one expects).

Pulled tensioner out and it was hosed. Replaced tensioner and still had noise on cold start - found Dinan belt not agreeing with the whole setup as it was too stiff or defective.

So we installed a JCW belt. Life is good with this setup.

I doubt you'd hit two bad pulleys (unless the shaft was banged up during the install) and two bad belts. So I think it is pretty safe to say the tensioner is the source of your misery.

 

I don't remember there being any slop in the tensioner pulley. I had a thought about the shaft being out of alignment, too, but was assured by the guy assisting (OK, leading the whole thing) that we didn't exert enough force to do that.

Glad to know that the belt isn't wrong. I didn't really doubt it, but independant confirmation is always good, right?

I'll check that tensioner slack again, just for the "laying on of hands", if you will.

Thanks for the advice!