i have a 79 ford f100. it has a 300 straight 6 with a c4 auto tranny. 2wd. my dad and i are building it. we just had the motor bored 30 over. everything else is stock. when we dropped the motor in today we ran into a problem. when we had the motor out of the truck and had everything in the block. when he turned it over by hand everything was smooth and there was no noise. we dropped it in the truck and bolted it to the tranny and turned it over and its making a clunking noise when turned over now. not sure what it is. we are assuming whatever is making the noise is in the transmission as there was no noise when it was not bolted to the tranny. any suggestions???

 

I think a bit more investigation is required.

But does the 'clunk' occur if the engine is turned over manually?? Does it bind?

Check they torque converter and make sure it is evenly bolted to flex plate. Again, rotate by hand.

 

Good possibility the torque converter isn't seated all the way into the pump.

Loosen the (4) nuts on the torque converter studs. Grab one of the converter studs sticking through the flex plate and wiggle it side to side in the flex plate. If you hear a 'clang,' the converter is seated. No clang and you'll have to slide the transmission back and reseat the torque converter into the pump then, restab the transmission to the engine.

I learned this lesson the hard way with a '68 Mustang I had with a 289 and a C-4 in 1983. --it was the first time I had ever installed an automatic. I had just had the C-4 rebuilt when I was reinstalling it.

It didn't run long before the transmission burned up and it damaged the two flat engagement places on the torque converter that goes into the pump.

 

it doesnt bind. but we rotated it by hand and we cranked it over with the battery

 

My first suspicion would be either the torque converter isn't tighten to the flex plate or the flex plate isn't tightened to the crankshaft flange.
Relatively easy to check. Pull the dust shield off the front of the bell housing and see if you can rock either the torque converter or flex plate by hand, you might need a screw driver or something similar, but if either is loose, it should'nt take much force to make them rock back and forth.

 

I checked both and neither are loose.. Any other suggestions?

 

Separate and disconnect the engine from the trans. Rotate the engine by hand by itself to isolate and verify the actual problem - the engine or the transmission.

Suspicion still surrounds the tranny and torque converter since all ya check was if it was loose... not whether it was seated and installed correctly.

Is there a reluctance to pull the engine or trans? New is new, rebuilt is rebuilt but that doesn't mean there isn't a problem with them. Then add the human factors and it can go to heck immediately. Dang those carbon-based units!

 

We pulled the motor again and found out it's something I'm the motor. Still working on it

 

The crankshaft is hitting the oil pump pickup tube... been there.

 

We finally figured it out. Turned out it was the timing gears had to much play. Thanks for the help

 

That's a really odd problem to have on a fresh rebuild. What happened? Specifically?