ever since i had the pulley changed, the s/c belt squeaks til about the temperature on the speedo reaches 1/4 from a cold start. if i leave it for anything more than an hour and it squeaks from the start (but quickly disappears after about a few seconds) i've done about 7,xxx kms with the pulley and jcw belt and it has always been like this.

i had my Mini dynoed about 3-4 months ago, boost was consistent so i'm guessing that my belt's tension is just right (if it were loose, it should be jumping right?)

 

I got the same sound from JCW belt & 15%.

I change to NAPA 25-060-535. No more slippage.

 

belt slippage = erratic boost right?

but the thing is, i had consistent boost in my dyno run. hmmm...

 

I had this with my 16% and stock belt so figured it was a good time to replace the belt. Went with the one that Chad at Detroit Tuned sell/recommends (along with a tensioner strap for protection) and I've had no noise since.

 

Do a visual check of the tensioner holes, there's a picture around here somewhere for reference. You should have at least half a hole showing. I use the 535 size with a 15% because it was slipping before with the previous belt. Not any more.

 

Also, check alignment as well. If the pulley is off by a fraction, it will warm the belt to stop squeeking after a bit, and then stay quiet. Easy to check as well if you are in there poking around!

 

Which Brand of pulley do you have ?