What's this engine noise? Vanos rattle or timing system issue?
 

At around 42 seconds after a cold start, I always hear a sound that is out of place, that coincides with the RPMs having gone down from 1K to just under 500 RPMs. It sounds like a marble bouncing around :-)

The sound does not seem to happen during driving, I can drive slow, normal or push the vehicle and I don't hear the noise.

I have isolated it to the area where the top of the valve cover meets the Vanos.

I don't think this is the "vanos rattle" issue, could it be a timing system (chain, guides) problem?

I have this video on youtube where you can hear the sound.

https://youtu.be/yPwr4Nv6QtE

I did work on the vanos a few months back and did the timing and have no codes... I'd appreciate some help :-)

I'd suggest getting a stethoscope and checking your idler pulleys. What happens if you have the AC on during start up? Same noise or different?
I'd also use the stethoscope on the accessories and waterpump. Maybe move the exhaust heat shields just a bit to see if something changes.

I've never heard a VANOS rattle in person, but yours sounded exactly as I would have expected it to. And I found this other video on youtube that seems to match yours. But BTW, yours is the best one out there, so you should leave it up there for others, maybe with an update after the fix.

https://www.youtube.com/watch?v=3KnsI4iK2wk

I did the VANOS rattle ring repair and seal replacement on my 3.0i when I had things apart for the head gasket work a couple of years ago. Very easy to do once you're in there, but ...

Interesting thing on the repair is that the new rings you use to eliminate the rattle are actually thinner than the ones you take out. Seems extremely counter-intuitive (even now, LOL), but I thought it all through back then - you put in thinner rings to account for the wear that has occurred, so things tighten up and there is no rattle.

Thanks guys.

I searched youtube and did not find that other video, but it certainly sounds exactly like mine. Thanks for pointing me to it. I will leave mine up.

Darn it... I just got through retiming the darn engine and I really don't want to get in there again...

Assuming it is the vanos rattle, is the vanos rattle just a nuisance or does it have the potential to damage things?

I think it's more of a performance loss problem than self destruct. Lean toward cosmetic annoyance. Look for other threads where people had the problem. How long did they have the problem beofee repair.

Also: try to bump up your idle speed. I did mine to remove in drive idle shake.