i just got done rebuilding my th400 and i put in my car and i overfilled the fluid a little because i figured it would go down when it filled the tc and cooler. when i started it, it came out the vent tube so i shut it off and let it cool a while and checked the level and it seemed fine. so i turned it on for a minute again and it started smoking out the dip stick. is this normal or do i have a big problem? also it was in park the whole time and when i went to put it together neutral wouldn't let me turn the driveshaft by hand. should i turn it back on and run it through the gears?

didn't soak any of the frictions in atf, the manual didnt say anything about it. i wonder if thats it?

There is there a vent tube on top of the transmission that might be plugged up. Are there any restrictions in the cooling lines?

If the drive shaft won't turn in neutral, I would not run it through the gears. The next sound you could hear might be a loud crunch. When my son and I rebuilt the transmission (manual T6) we had the same thing, and I was tempted to start it up. We thougt better of it and dissembled the whole transmission, only to find some small pins out of place. If we would have started it and ran it throught the gears we would have caused a lot of damage.

You could have pinched the vent tube on top of the transmission when you put it back in the car.

i did run it through the gears and its not smoking but it keeps shooting the fluid out that tube

Justin,

Sorry to read this. Please keep us informed on the cause and fix.

I did see some mentions of blocked vent on top and overfilled trans due to mis-installed dipstick?

Justin, I think the vent tube is the primary suspect. You could have trapped it when installing the transmission, or it could be blocked with crappage. If that vent tube is blocked, internal pressures could shoot transmission fluid out the dipstick tube. Also, as Mike mentioned, make sure the dipstick tube is properly installed and seated.

its not coming out the dipstick its pumping a steady stream out the vent tube. the dipstick is matched to the deep pan i have, i had the guy that built it the first and second time change it to the right one. but doesnt matter if its down lower than the line it just pumps it out. pressures seem to be in spec as listed in the manual. ive read on searches it might be the pump gasket? it was all replaced but that one was a complete pain to line up i wouldnt be surprised if it was messed up

Sorry to suggest this, but I think you may have to tear back down and retrace all of your steps.