M30 Swap done...now on to the bugs

[SpeicherBimmer]

So as you may know from my other thread I have just about completed my euro M30B34 swap. I've been driving it around town the last few days and everything has been fin except for one thing. The car makes this clunking,thwacking noise on occasion. It doesn't happen at any particular engine speed or gear, but I can feel it vibrating somewhere in the driveshaft tunnel/transmission area. I've looked underneath the car and can't find anything that is awry; it all seems to be nice and tight. At first I thought it might be the driveshaft, but I would imagine it would do it either all the time or in one spot on the RPM band...the trans has fluid as does the diff. The only thing that isn't tight is my shifter base as I just have something rigged up until I can figure out how to actually mount it to the car. That isn't the issue though as it doesn't move enough to come into contact with anything....Anybody have any ideas?

[yert315]

pretty vague description, but I'll give you a few places to look.

1. Driveshaft CSB (Center support bearing). The rubber may be cracked and is letting the driveshaft bounce around.

2. Guibo/flex disk. Check for cracks, fraying, loose bolts, etc.

3. differential. Check mounts, axles and driveshaft tightness.

4. I would still be wary of the shifter bracket. Find a solid mounting solution and go from there.

[SpeicherBimmer]

Thanks yert, I know my description wasn't very good but it is hard to describe a sound, especially when it doesn't do it consistently. I got the car up on a lift and thought I found the problem; a nub that sticks out of the block on the passenger side was hitting my headers if I applied any sort of pressure on them making a noise similar to what I had been hearing. I cut about half the nub off and have about 1/8" clearance now. I thought for sure that was the problem, but low and behold it did it again driving home. It doesn't do it nearly as bad now, and I noticed now that it does it more when the engine is cold than when it is warmed up. I looked at the guibo and CSB and didn't really see anything out of the ordinary.
I noticed today how hot this thing runs too; even with no thermostat I was sitting right at the half mark or just above driving around Bitburg. There is was a ton of heat emanating from the shifter base; the actually selector rod was hot to the touch. Is that normal for these things?

[wildstoats]

Yeah, mine gets pretty hot, especially if it's hot outside. What are you doing for a cooling setup by the way?

[SpeicherBimmer]

well right now I don't have anything extra; the fan I ordered hasn't gotten here yet. I pulled the Tstat out until I get the fan and have it hooked up.I also ordered the Alpina radiator for the position 1 cars that I found on German Ebay so the dist isn't touching the rad anymore. With no tstat I have no heat, and the car takes about 15-20 mins of driving to get to the 1/4 mark, then another 5-10 mins of city driving to get to the half or just above. I have an OEM tstat waiting for the radiator and fan to get here.
To make sure I got it right, the hose coming from the back of the cylinder head goes to the top heater core input and the hose coming from the tstat/reservoir goes to the bottom heater core nipple on the firewall?