Clunking Between Bellhousing and oil pan..
 

On my '92, 302, i'm having a clunking noise which sounds close to a rod knock. I've pulled each plug wire while running, and the noise doesn't change any tone. I noticed that if the truck sit's for a day or two, and the engine starts off on a low idle, it won't do it for a minute or so.

I've been told there is a chance the Flex-plate may have cracks around the center where the crank bolts are. I pulled the inspection cover off the tranny, but cannot see any cracks around the welds of the flexplate. I looked best I can near the center of the flex-plate, but all I can see is what I would looks to be reddish, rusty looking discoloration. I got a socket on the torque converter bolts and they're all snug and tight. I then got a socket on the crank and a socket on the torque conv. bolts. When I move them in opposing directions, I get a light clunking noise right at the lower end. I think it's a 2-5% turn and then back when I hear the clunk. I've tried the garden hose for pin pointing the sound and it's not a definate for the tranny but about an inch from the bellhousing towards the engine, it is.

I've already replaced the mains, and the rod bearing and I've checked for bearing material in the oil. Everything appears to be ok. Has anyone run into the same situation?

As you say, cracked flexplate. Or loose flexplate to crankshaft bolts. Both are possibilities.

The red you saw is prolly rust from the cracks

^^^what he said^^ had i happen on two diferent engines

Thanks for the replies everyone!

My next question is, do I have to loosen the converter attaching nuts in order to slide the tranny back , say 3 inches, to gain access to the flexplate? I have the drive-shaft unbolted, the 4wd driveshaft from transfer case unbolted, the tranny bolts to bellhousing out. I took the 19mm bolts out from the tranny mount. I got the tranny to slide back 3/4 of inch, but I just want to be sure I doing it right.

I have the tranny on a transmission jack and the oil pan supported with a bottle jack and a block of wood. Anything I have missed?

I would unbolt the t-case from the trans. It makes balancing the trans on the jack ALOT easier and it is only 6 bolts. And use a small ratchet strap to secure the trans to the jack. Or be a heman and just pull the trans by hand like ME:-D

In theory you can leave the torque converter bolted to the flex plate and still remove the trans, but i would not suggest it. Take the 4 or 6 nuts off that hold the TC to the Flexplate and take the TQ out w the trans