By recently bought 2007 - 328i with 94k miles, and it is making sound. More audible at idle outside the cabin. In cabin it is not bad. But I was wondering is this knocking? Or valve lash?
This is coming from passenger side of the engine bay, it seems like coming from below the valve train. But it might be possible it is coming from valve train.
Any ideas on what it is? and how to fix it?