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Have just replaced the R56 N14 engine in my 2010 Mini Cooper S with an OEM long block. Block came with a new water pump and I moved all other accessories from the old engine (scored cylinders and warped head). Installed a new belt and everything seemed to be OK. Installed engine, buttoned everything up, cranked it a few times to establish oil pressure, then started it (started 1st try). Letting engine warm up and at about 5 minutes in the Serpentine belt started to spread itself....any ideas on
what to check?
No. Suggest you check all pulleys for freedom of rotation. Then, correctly route a new belt and start it up. Watch the belt tracking with the engine at idle. If something if out of alignment, you'll see it right away.
Never had to do this with my MINIs but with other engines I used a precision straight edge (from Snap On tools) to check the faces of the various accessory drive pulleys were all in the same plane.
The other way is the good old calibrated eyeball... Not perfect but one should be able to spot a "big" alignment problem. That the new belt shredded itself in such a short time suggests the alignment was way off.
A sign a serpentine belt is not tracking properly is one (or both) edges are "sharp". I encountered this one time with a recently replaced belt and the culprit was the water pump bearings were worn and this allowed the water pump pulley to be pulled out of alignment. Not by much but enough. (I had an old belt with about 60K miles on it and got it out for comparison to the recently changed belt. Both edges of the old belt were dull.)
I'm betting it wasn't on the pulleys correctly. It can be really difficult to see and verify that the belt is on the grooves correctly. It is so tight up in there.
