Originally Posted by Jim165
From the video, it looks like a 545 instead of a 550i. That difference could possibly change what could be the source of the noise.
Originally Posted by DanielFD
that is a 545i engine. They are pretty similar though. The only real difference is in the cylinders. Anyway i dont think i've ever heard an engine make a sound like that. If its coming from under the AC filter there (next to the positive battery terminal) then thats where the brake booster is. I'd take off the filters and surrounding plastic underneath and see if something is loose.
Is it because of the engine cover? It's a 2008 550i and is badged as such...thought the engine change in 2005 changed the 545 to 550.
It does sound like it's coming from near the back of the engine, maybe a bit close to the brake booster...I took apart everything save for removing the brake booster and checked it all - no leaks, lines hold vacuum.
Could it be the PCV? Thought I read something about a malfunctioning PCV system making howling noises (will try to find a link). I watched several videos of oil separator malfunctions and they make a completely different, continuous noise.
This starts up when the car is warmed up and comes and goes every several seconds.