Rattle noise idenfitication

[hli]

I've been getting a marbles in a tin can rattling noise in my E36 since I've owned it. Its only been noticeable at idle with the windows down after hard acceleration (after autocross runs, etc.). If I tap the gas at this point it agitates the rattling. Problem doesn't exist at all on a cold start. I initially thought it was the catalytic converter breaking up and going bad as I'm also getting the tell tale rotten egg smell, but I came across this video today which seems to show the same exact issue I'm having but the guy says he isn't running a catalytic converter at all, so now I'm questioning what the noise could be. It seems to be too sharp/high pitched to be the VANOS, and I recently overhauled that. I've also whacked most of the exhaust system and wasn't able to replicate the noise so I do not believe it is a loose heat shield . Any ideas?
https://www.youtube.com/watch?v=UZu7...youtu.be&t=212

[Carpy2]

The sound you describe sounds like VANOS, but it would be coming from the VANOS unit at the front of the car, and would be very obvious. The sound in the video doesn't sound like VANOS at all to me, it's more like a ticking than marbles in a pringles can (like you said, a higher pitched sound), and it isn't coming from the front of the car.

When you say it's only noticeable at idle, do you mean it goes away at speed, or it's so quiet that you can't hear it while moving? Do you notice a difference with the clutch engaged, not engaged? My initial jerk reaction is a bad throw out bearing, but the only bad one I've heard in person sounded a bit more grindy, but still pretty similar. Noises like this can be created from bad RTABs, cracked rear strut towers, (although those would happen while moving, not really at idle), and much more, so a bad TOB is just a shot in the dark.

I would start with getting the car up so you can stick your head underneath it to pin point the exact location more accurately, then I think some of the other more experienced members can help. Good luck.

[hli]

The noise seems to disappear completely after you rev past a certain point (maybe 2000 RPM or so?). I know for certain it's not any suspension component because it happens while completely stopped. Happens regardless of clutch position. Maybe it is the catalyst material after all, and the guy in the video just didn't get all of it out when he punched his cat out.

[crqflier]

You talking about the sound at 3:40? That sounds like a heat shield rattling against the exhaust. Could be your cats, his cars are gutted, but could have some loose structure. I had a dinan gen 1 muffler that had internal welds corrode - made a similar rattle at just above idle.

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