Well I said rock in the exaust, but glad you found it. you had a very good recording and it really sounded lower and it sounded like it was hitting iron, not aluminum... surround sound is AWESOME!
John

Good job, I once had a loose nut inside my front exhaust pipe that made a bunch of noise under the center of the car. I wasn't that hard to figure out because I had just had the front pipe replaced.

VStech - I think it was more your intuition or experience that located the sound - I recorded it in mono! :)

Just shows - two pairs of ears are better than one!

NOw if I can only get that damm thing out.... If I can't get it out, what are the chances of it causing havoc? Is the flywheel made of much harder metal than a regular nut?

If I loosen the bolts on the flywheel (like you do to replace the flex plate), what will happen?

Well, I would be worried where the nut came from
 

I am not really versed in how the TC bolts to the FW, if that is a bolt from there, you cluld be unbalanced and it could also crack the FW, I would get a remote starter switch and with the vehicle SECURELY supported and blocked, Like on 4 drive up ramps with the E brake solid, or 4 6 ton(the 3ton's really don't give you enough room with the whole car raised) jackstands, start prying on the FW and see if it can come out, but also verify that all bolts are securing the TC.
if that bolt/nut combo is jsut a loose set from GOKW, it could still be damaging the case of the bellhousing or your block. also, everytime the thing gets wedged between block/case/whatever, the crank endplay could be getting whacked. not a good thing.
John

The bolt doesn't seem to be part of any set I can see.

I even took the starter off becuase I thought maybe it was from there, or at least I could get to it from the starter housing. But no. There is no way to get that bolt out, short of taking the tranny off. At least as far as I can see.

I figured since it might be in there for a while, it may as well get comfy, so I put some grease in there with it, and it hasn't clanked once since I've driven it since.

I am wondering if this is the reason there is a whump whump vibration at about 65mph, and it vibrates at low revs, like the engine mounts are bad (they aren't - I just changed them).

Anyway, I don't see any reasonable way to get that bolt out, and since it doesn't seem to be doing any damage, I am going to leave it and hope it behaves itself.

Or I get wise from a 240D guru who tells me what it's really doing up there and how I get it out.....


VStech, what do you mean "start prying on the FW and see if it can come out" - what is 'it' that can come out? The nut?
And what does TC stand for? Transmission Case? Total Crap? Transylvanian Causcasian?