I have a 2005 545i with 201,000 trouble free miles. in the last 6 months I have a sound like a goose honking coming from the area of the oil filler cap. It goes away when warm and has recently become a steady sound upon startup. It's not real loud, but you can hear it clearly.
I'm wondering if it could be the orange pressure regulating valve. Last I checked it, about a year ago, it looked good. I know those can go bad easily. There are no other problems and no codes. I'm currently using BimmerCode and BimmerLink on my phone. I also have INPA and don't have any related codes. Just Klima and the alarm battery.
Anyone else have waterfowl in their valvetrains?
Thank you
Tom K.

 

Try doing a smoke test.