94 325i crank case rattle/knocking

[yee36]

First post so bear with me. My car is a 94 325i sedan, 171k miles, bone stock afaik, most recent oil change was <1k miles ago.

There is a ticking/rattling/knocking noise coming from my crank case(the silver part of the valve cover at the front of the engine), if you put your hand on the top of it you can feel it knocking. The engine runs and sounds fine otherwise and the vanos seems to still be working well enough. The noise is most prominent at idle and below 2k rpm, after that I stop hearing it. Not sure if its going away or I just cant hear it as well. Its also more prominent when the engine is warm. I had my mechanic friend listen to it and he said it doesn't sound like lifter tick or rod knock because of where its coming from, and because its not fast and clicky like lifter tick its slower and inconsistent almost like a belt or a tensioner which was my guess until he pointed out the crank case. The best I can describe it is that it almost feels like a piece of something broke off and is rattling around in the crank case but I could be way off. Any suggestions? Thanks.

Edit: I should add that I know the car has a vacuum leak somewhere and it causes a high pitched whistling noise that comes on and off, as well as a leaky oil filter cap. Not sure if its related but I figure its worth mentioning.

Edit 2: sounds almost exactly like this https://www.youtube.com/watch?v=ufpX4gufCqo but not as pronounced when revving.

[Eric93se]

Probably chain guide broke off. If you do this job, replace both chain tensioners and rebuild the vanos. Bessian systems website has a good guide. Only problem with the guide is where they use an exacto knife to cut out the old seals, stupid people cut into the vanos like one of the previous owners of my car.

[spyderg0d]

could be anything. vanos, lifters, crank bearings, piston slap.