Quote Originally Posted by FiveOJester
Hello All,

I'm pretty new to BMWs (this is my first and I've had it for 3 months) so I'm not sure if this sound is normal or not. I get a pretty distinct whistle at idle. Not really sure if it remains beyond idle because the rest of the normal BMW engine noises (I think the cam chains that make the whirring/whining noise as you rev) either drown it out or it goes away.

I pulled off the plastic engine cover and rubber insulator and placed my ear in the vicinity of the intake and was able to hear a definite whistle which is not really that loud. The car runs fine and throws no error codes in a stomp test. It idles a little rough, but about what I'd expect from a high-revving, high compression engine. A bit rougher when cold. Is this an indication that the intake gaskets or PCV (diverter) valve might be leaking or am I just being overly paranoid and hearing a normal BMW sound?

P.S. While I was poking around under the hood I noticed some oil below the intake on the front driverside. Looks like I've got some kind of leak so I might be taking off the intake anyways.
Read the threads by Been-Jammin' in the past day or so -- there's a lot of info in them to be found on this problem. I'd suspect a vacuum leak somewhere in the air delivery part of the intake on the whistling sound. Oil could be from a timing cover (unlikely) or the oil return line under the intake (again, see the posts by "benjamin" and the various replies -- Bill posted a picture that includes said line, IIRC).


best, whit