Hello,

I have an '03 R53 with 131k and a 17% pulley. I have driven it about 200 miles since changing the SC pulley and replacing the belt with the 60535.

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Today it started making a very load squealing noise, very high pitched. One second no noise, next second painfully obvious. I saw on another post that this could be an issue with the belt, although I thought I had the right belt. I am also not sure why it has been fine on this belt for as long as it has if the belt is the issue here.

Could it be a different issue than the belt? How would I test to find out?

I had the car trailered back to the shop just to be sure, so hopefully it didn't have time to do any major damage, whatever it was.

 

Have you checked your crank pulley? If it is stock it may be separating.

 

Yes, I took it off to check it about the same time I replaced the SC pulley, and it was still in one piece.

 

When my alternator went bad (bearing), it was making an awful noise.

If it's a belt noise, check the tension first. If it's fine and the tensionner is fine, remove the belt and check the pulleys

 

Figured it out! It was an air leak from the passenger side supercharger horn, where it seals with the intercooler. The rubber seal was folded over on the bottom and air was able to escape there. Realized that may be it because the sound only occurred when I went off the throttle, so the pressure was built up enough to make the noise as it rushed out.