[alexwhittemore]

I'm at 60k miles and out of the new car warranty (still under CPO) thus thinking about maintenance items I need to DIY. One of the things recommended for 60k intervals by the more conservative schedules is the serpentine belt. I'm at 62k.

Well, looking at mine, there are no visible signs of wear really at all. The ribs look good, the back looks good, the rubber doesn't look at all dried out or cracking, it looks like you could pass it off as new. All the pulleys look good too, but then I don't really know what to look for there to decide whether replacement is advisable.

Thoughts on these two points, besides "better safe than sorry"? Partly I'm inclined not to care because even if everything went to hell, as of now it'd be covered under warranty. But you know, still better to make an educated decision.

[mweisdorfer]

I'd leave it alone and make the tensioner, belt and pulleys a year to year decision if they look brand new like you stated. I just changed mine out and I went 99k. Belt looked pretty good to be frank; pulleys and what not weren't bad either.

[Meeni]

I changed my belt at 100k, both pulleys were shot, the belt was in pristine condition.

To test the pulleys, you need to relieve tension on the belt, if the pulley free-rolls and make a "trrrrrrrrr" noise, its dead. It should make no noise and stop turning quickly.

[alexwhittemore]

Originally Posted by Meeni

To test the pulleys, you need to relieve tension on the belt, if the pulley free-rolls and make a "trrrrrrrrr" noise, its dead. It should make no noise and stop turning quickly.

Awesome, thanks! I'll put this one on the list for "check at 100k" then.

60k is conservative, I would wait till 80-100k and do the belt tensioner and idler pulley at the same time.

On the 335i, at least, I've heard of too many "broken belt going through the crank seal" issues to not change the belt/tensioner/idler early. I did it at 56k while doing other maintenance items. All looked well, but better safe than sorry.