Introduction - 1995 BMW M3 Coupe

[jaimerod]

I'm trying to get things to run as smoothly as possible and I noticed some odd noise today. It sounds like a quiet howl/whistle at idle. When I open the oil cap the noise stops. When I put It back on it starts again after 5-10 seconds. Anyone know what this is? Seems like excess vacuum? PCV valve maybe?

Here is a video:
https://photos.app.goo.gl/3czCgQoqcozUN9Dd8

[jaysonx]

Pressure is building and not being vented properly, start by checking all your crankcase ventilation components for clogs and functionality. Chase the hoses to where they terminate to be sure (I recommend replacing them regardless).

https://www.realoem.com/bmw/enUS/showparts?id=BF93-USA-09-1995-E36-BMW-M3&diagId=11_1284#11151703710

[bmwstephen]

Just another observation but the orientation of your side markers are also flipped. It looks like the driverside was installed on the passenger side and vice versa. It should be slanting pointing towards the direction of the wheel well.

[Boltz]

Couldn't the CCV just naturally make these sounds. I mean it's working with a swirl or tornado kind of system to seperate oil and air. I could imagine that fast air in there could produce some sounds.