Strange thing I forgot to mention is that the engine seems to stop in exactly the same rotational position everytime. When I was replacing the rocker arm, I noticed the engine always stopped at exactly the same place. I noticed becuase I could easily remove the rocker arm everytime.

Is that an indication of something?

As a recap, here's my symptoms and attempted cures

Clacking noise that starts when the car gets warm. Is a lot quieter with the 4th cylinder exhaust valve tightened down to 0.06" instead of 0.13".

The sound is like something loose in the valve cover flying around, or like a loose bracket slapping against something. It is coming from the back of the engine on the air filter side.

I have taken off the intake manifold and injector and glowplug and poked around with a magnet - nothing came out. I also turned the engine over with the glow plug removed to see iif it would spit something out.

The other symptom is a hard sharp thwack when you put a steth on injector line 4. You can feel it with your hands too. But since the clacking doesn't stop when the injector line to 4 is cracked open, I don't think it is the injector, so I haven't really bothered investigating it too far.

So what to do next? This is the first synthetic oil change I have done, so mabye some major sludge or who knows what came loose?

It's a lottery. And my darling slug has been sitting idle for 2 weeks. I did take her out for a spin after I filled her up with my first full tank of homemade B100......

Have you rotated the engine, manually, to see if the noise might persist? I'm doubful, but, with the engine stopping in the same place each time, a manual rotation via the crankshaft might tell you something.

yes, I've turned it over manually lots of times to set the valves. I think I was turning it the wrong way (anticlockwise) in the beginning, and it was hard to turn every now and then. But going forward (clockwise) I didn't notice anything strange.

Could I have screwed something up turning it backwards a few times?

I doubt that you damaged anything by turning it counterclockwise. It's not a great idea because the chain can possibly catch the bottom of the tensioner, but, you'd know this right away. It might have been the "hard to turn" scenario.

You mention that the noise is not from the front of the engine, so, I tend to discount any damage to the tensioning rail.

WEll, after a lot of soul searching, sleepless nights and soaking myself in spirits (OK, not really), I found the source of the clacking.

Remember in the beginning I said it sounds like something flying around in the valve cover (You don't remember?) Well, it IS something flying around, but not in the valve cover. The sound is deceptive. It was actually coming from the torque converter. When I took the cover plate off the front of the tranny housing where the flex plate is, I saw a nut and washer loose in there! Just hanging out in a groove between the flywheel and the tranny housing....

They're stuck in a funny position where I can't figure how to get them out, or how the heck they got in there. All I can think is the owner before me put on a new tranny and left an extra bolt in there for a surprise. Thanks buddy.

So now, apart from taking off the tranny, I don't see how the heck to get the nut out. The car is hardly clacking at all any more - I've been driving it around - so maybe the nut will wear itself out. Or maybe it will wear down enough to turn 90% and destroy the flywheel? I don't know.

Tomorrow I'm going to buy a magnet and see if I can coax it out somehow.

Thanks for all the suggestions, especially the chap who said to check the torque converter for a rock stuck in there./..... The sound was really deceptive, I could have swore it was coming from the valve cover.

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?

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?