OK - Disclaimer, this actually happened on my son's '89 BMW 525i M20 engine, but its cooling system is similar to a 240 that has a V-belt off the main pulley that drives a water pump pulley that is also attached to a viscous clutch tyoe cooling fan. But I think Brickboarders would still be interested.

The engine overheated, and when my son got home I inspected the engine and noticed that the fan was not turning with the engine running. The belt was turned inside out and off of the pulleys. It was also stretched and had necked down to about half its original thickness in one area. My son said the belt had been squealing for a few days but went away - shortly before overheating. What a coincidence!

My guess is that somehow the belt got loose and jumped off the pulley, got twisted around the shaft and then stretched. Any thoughts? The belt tensioning method is quite different from a b230 in that BMW uses a gear type tensioning system.

Thanks,

Tom

check the alternator bushings. make sure it's tight and the adjustment rack is ok. lotsa them have stripped teeth there or the nut itself. usually, i pull the alt and replace it all. everything spins ok, right? if you need to replace the pump, remember it's part of the timing belt tensioner. look on the bright side, if you need a belt, you shouldn't need front seals. good luck, chuck.