N55 Rattling sound near alternator, belt area

[huzaifa]

Anyone have experience with a similar sound, only hear it on idle, coming from belt, ofhg, alternator area. OFHG is leaking, having that replaced this week, any ideas what it could be?

[ErvGotti]

For me it was the alternator bearing. The bearing the pully mounts on was worn. It was hard to notice besides the noise as the belts and pulleys felt fine while everything was connected, but as soon as I removed the belt, there was alot of play on the pully. You can replace the bearing and pulley, but if its already making noise it's too late and will have to replace the whole assembly.

[huzaifa]

For anyone who runs into a similar issue it was as suspected, the ofhg had leaked oil onto the belt tensioner and belt, replaced the ofhg, belt tensioner, belt and idler pulley together and sound is 100% gone, smooth now. Most threads note it is a squeaking issue with the belt however mine was a rattle like a loose bolt shaking, which would have been the sound of the bad tensioner bearing due to the oil leakage.

[jkirk454]

I'm having these same symptoms. Just dropped my '12 135i at the shop. Hopefully something small!