The MINI started to develop a squeaky belt recently, and I've begun to diagnose it. My original thought was it was the idler pulley, but after ripping off the wheel liner, I noticed the crankcase pulley bolt is wobbling. I'm assuming this isn't normal, and is an indication of the pulley going bad. Can anyone confirm this?
The belt and belt tensioner are new as of last year since I replaced both when I went with the 15% reduced supercharger pulley.

 

If you take the tension off the belt and can push the pulley so that it hits the motor, the pulley is bad. How many miles on the car? Our Gen1 cars are now pushing 10 years old and in some instances more. The rubber that holds the pulley together rots out.

A betting man would say it is most likely the crank pulley.

 

The part of the crank pulley that fails is the outer ring - it will essentially fall off leaving the rest of the pulley on the crank. The failure is the rubber connecting ring disintegrating - I don't think that would cause a squeak.
I thought I had my squeak narrowed down to the idler pulley, but it turned out to be the tensioner assembly.

 

I took off the belt so that I could see how all of the pulleys were. All spun pretty freely with no noise. The belt seems fine, too. I did notice that I could move the crank pulley a little back and forth. The car has 61,000 miles and is a 2006.

 

Good to know. The tensioner assembly was replaced last year along with the new supercharger pulley, so I don't think it's that. If the crank pulley wobbled at all, wouldn't that cause the belt to squeak?

 

I have no first hand experience trying to wiggle the crank pulley on the Mini. However with my experience with modern cars you should not be able to cause it to wiggle with your bare hands if you are not superhuman unless the pulley damping material (rubber) has deteriorated. I suggest looking closely at the rubber for cracks. May be try plying with a ply bar and inspect it. The way that center bolt head is wobbling is troubling too.

 

Thank you. I noticed it wobble back and forth when spinning. It seems that the rubber is bad. I didn't have a pulley puller and need the car on the road for work today. Since all signs point to it failing, i decided to order a new ATI crank pulley from Way Motor Works. If by some chance it's not the issue, I at least won't have to worry about the crappy OEM pulley failing anymore. Holy crap is that part expensive.

 

My pulley does not wobble as much as yours was. I just replaced a pulley on another car as it was wobbling. When I pulled it off you could see the rubber was cracked.

Let us know if new pulley fixes the problem. And yes, replacing my pulley is on my list of things to do this summer.

 

I just replaced the pulley today with an ATI super damper, and the car no longer squeaks! The pulley showed very little signs of wear. When I had it off the car, I could move both parts slightly back and forth by hand.

Thanks for all the advice!

 

No thanks needed. You drive a Mini just as I do. We need to stick together.