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      11-21-2015, 03:06 PM   #15
First Lieutenant

Drives: 2011 335i
Join Date: Dec 2014
Location: Thousand Oaks

iTrader: (0)

Update: 3 months after replacing the front main seal, the rear main blew, sounding exactly like this:

It turns out that the seals aren't actually "blowing", they're just sucking -- literally sucking in air and whistling like a party balloon. In my case this was the result of a failed PCV valve allowing excess crankcase vacuum. I replaced the PCV valve, not the rear main seal, and all is well now.

Detailed PCV valve info here:
Appreciate 0