I have an '05 Cooper S. It runs fine when cool, but once warmed up the alternator locked up. The belt was turning but not the alternator. OK easy fix. Replaced the alternator; new one does exactly the same thing. Any ideas? By the way, new to the forum.
Thanks, Rich

 

Rich,

a few things come to mind. Double check to make sure that the Alternator is infact not turning, I would remove the belt again and then turn each belt driven accessory by hand, and make sure none are seizing. I would also check and make sure that the belt tensioner is applying proper pressure to the belt. I would also visually inspect the pulley on the crankshaft as they tend to seperate and cause problems.

Its possible you had a defective replacement alternator (especially if its a rebuild), but its much more likely that there is another problem.

 

Old thread but for anyone considering replacing their alternator: Pelican Technical Article: MINI Cooper - Alternator Replacement