TH 400 Damaged

[cppursell]

My friend is experiencing some woes with his TH400 transmission.

He was putting in a new engine in his '64 Chevy C10. He hooked up the torque converter to the flywheel apart from his transmission (BTW he didn't fill the torque converter with fluid, IDK if that's important), then tried to bolt the transmission to the engine. While he was tightening down the transmission he said he felt resistance, but kept going, and he then heard a loud "pop". He took a quick look inside the transmission but didn't see anything broken, so he proceeded to finish installing.

Now my friend's truck is running, but the transmission won't engage. We both fear the transmission is ruined, but perhaps a part broke inside that can be (relatively) easily replaced. Could it be the fluid pump that broke? How easy is it to take these transmissions apart?

Thank you for your helpful responses.

[dwcsr]

He broke the pump. Never bolt it up to the flywheel and draw the trans in. Those 2 slots on the converter have coresponding tangs on the pump. Always put the torque converter on the trans rotate it til it pushes back in to pump slots. then mount the trans and slide the converter to the flywheel and bolt it on.
Now you have to take the front pump out and replace it.

[cppursell]

Thank you for your wise answer! Yes, once I research on auto tranny parts, I suspected he broke the pump. Now: Where to get a pump, how pricey are they, and most importantly, where can I find instructions on how to do this repair?

Thanks again for your insight!

[cppursell]

Update: I informed my friend of this post and he's thrilled that he only broke one thing! He's going to try a transmission shop tomorrow for the part.

Thanks again, dwcsr!

[cableguy0]

You need to make sure he didnt trash the splines in the input shaft and the torque converter itself. The converter also needs to be checked for cracks. I would also be checking the bellhousing very closely for cracks.The transmission really need to be pulled apart and cleaned just to make sure the pump didnt manage to push any metal through. The torque converter could also be damaged from being run dry.

[cppursell]

Originally Posted by cableguy0

You need to make sure he didnt trash the splines in the input shaft and the torque converter itself. The converter also needs to be checked for cracks. I would also be checking the bellhousing very closely for cracks.The transmission really need to be pulled apart and cleaned just to make sure the pump didnt manage to push any metal through. The torque converter could also be damaged from being run dry.

When we eventually get his transmission out and open, we'll inspect it according to your advice to the best of our ability.
Thanks!