[LanDzia]

I've noticed recently this weird noise coming from engine n52 2006 at 100k miles.
It'd NOT a lifter tick and not any of the pulleys as these been changed.

It sounds like a small piece of metal/aluminum rattling back and forth.
It starts roughly from half way of the clip and gets more evident by the end of it. Very distinct "metal on metal" sound.

https://youtube.com/shorts/XxhFgCDdB...Eim8cwUOyvCYZG

Any ideas what it can be?

I've heard these first n52's had failing aluminum head bolts which cause oil to leak. Maybe that's the case?
A few bolts that are outside look solid, no movement in them, but there are a few under valve cover which I obviously can't see (VC has never been done yet. No visible leaks from it).

[LanDzia]

Another thought - a week ago I've changed large disa valve. Previous one was original. It was broken off at the top part and at around 3k rpm it would try to open and rattle around.
One thing Im not sure is - pin. I know newer disa's have metal pin inside, which could potentailly be stuck in manifold making such sound.
That being said, If I recall early models of 2006 330i with n52 had disa valves with plastic pins, which brake off, but keep the flap within disa unit flapping around (just like mine was). Not 100% sure on this, but it seems like it. Even new part sourced original BMW looked like with plastic pin.