2nd Gen R56 Cooper S 2nd gen Serpentine Belt Replacement

Anybody know of a DIY on this maintenance item? I have a buddy with a thrown belt and it just seems like a rare event for a 2nd Gen.

BTW, Obviously the AC and Alternator runs from the belt, but I am not sure about the Water pump, is it belt driven? It seems like the water pump is friction driven from the crank via an idler,as opposed to an actual belt.

 

I have an R53 and just trying to help a buddy that threw a belt today on his R56 JCW. Anyway, it just seems like a very rare event, his car has ~40k mi. My guess is that if it threw a belt then there is some root cause on why it happened and that must be remedied as well as just a new belt.

The R56 is very different from the R53, obviously with the SC, but also with the water pump and the way it is driven. I guess I am just not familiar with the friction driven water pump pulley configuration.