Zchryst

Yes, local BMW dealer. Tell me about it!  It’s not just the dealer who leaves me with little faith, the service manager sent it to the BMW field rep who came back with this...

“My first guess would be to check the crankcase pressure. It almost sounds like air escaping past the front crank seal.

Otherwise the only way to pinpoint the noise is to catch it happening.”

Doesnt sound right to me at all, so I came to this group figuring I’d get answered/thoughts from people who aren’t just looking to sell me new tires when my tread still has 30k miles left. 

Your answer makes the most sense of anything I’ve heard yet. Thanks!

Anyone have any ideas?  It’s located in the front left (US driver side) engine compartment. 

It sounds for about two hours while it’s parked after driving enough to bring it to operating temperature.  It doesn’t start right away, maybe 30 minutes after it’s parked.

Thanks all!

Zach