I recently bought a 2006 Mini Cooper S R53 with 130K miles. Love the car but having problems with the serpentine belt. The first day home with the car the belt shredded. I installed a new belt tensioner and serpentine belt. Everything looks to be aligned correctly, but after the engine runs for about a minute, the belt jumps one groove back toward the supercharger on the SC pulley.

I replaced the Cravenspeed 15% reduction pulley with a new one just to make sure that the pulley was installed correctly, and the same thing continues to happen. About to go out and remove the belt tensioner and inspect the alignment on all of the pulleys very closely to see if I can determine what is pulling the 6-rib belt off track. Since the idler pulley and tensioner pulleys are just smooth wheels, I am assuming it has to be the SC pulley is not pushed in to the correct position on the SC shaft, or either the crank pulley or alternator pulley are out of alignment and pulling the belt toward the engine to cause it to jump over one groove on the SC pulley.

Hopefully I will have this figured sometime today. If so, I will post the solution. Would welcome any input from others that may have already solved this problem. Thanks!

Tom

 

Update - I reinstalled the SC pulley and made sure it was seated as far as possible on the supercharger shaft. No change. The belt jumps back one groove towards the engine as soon as the engine is started. I am back to my assumption that the alternator pulley is out of alignment with the SC pulley.

If anyone has ideas or suggestions, that would be welcome.

 

Not sure if I am the only one that has run across this problem, but just in case I am not, here is what I found. . .

There is a tabbed retainer on the snout shaft seal that had fallen off and was spinning around behind the SC pulley and eating the belts like a cheese grater. I knew that retainer had come off. What I did not know was that the output shaft can MOVE. Not knowing much about superchargers, I assumed the output shaft was in a fixed position. But without the tabbed retainer in place, the seal and the shaft had slowly moved outwards, placing the 15% reduction pulley out of alignment with the other pulleys over which the serpentine belt is routed.

I gently tapped the shaft in until it was at the correct position for pulley alignment, seated the seal into its correct position and installed a new tabbed retainer. After that I was able to re-install the SC pulley and put everything back together. I am a little concerned that there may be some damage to the supercharger from the shaft movement, but the car is running fine and no problems so far.