Im not fantastic with transmissions but it does have to be one of three things.

The drain bolt on the converter. Maybe its cross threaded, not tightened down, or you changed the plug and the new one wasnt NPT thread.

The convertor seal. If its a new seal, and I trust you installed it at the correct depth and orientation, the spring must have popped off when you slid the converter into the pump.

Pump seal. Maybe it was pinched during installation, maybe a defective gasket, or you forgot to torque a bolt.

Theres a chance of a cracked converter around the welds, but thats usually an instant find.

 

Im not fantastic with transmissions but it does have to be one of three things.

The drain bolt on the converter. Maybe its cross threaded, not tightened down, or you changed the plug and the new one wasnt NPT thread.

The convertor seal. If its a new seal, and I trust you installed it at the correct depth and orientation, the spring must have popped off when you slid the converter into the pump.

Pump seal. Maybe it was pinched during installation, maybe a defective gasket, or you forgot to torque a bolt.

Theres a chance of a cracked converter around the welds, but thats usually an instant find.

First thanks to everyone.
The new torque converter does not have a drain plug.

When i took it back out the second time i checked everything. The seal looked good with the spring in place but i replaced it anyway with a new seal. I did test fit the new one to the torque converter before installing. I took the pump apart and both gaskets looked good and the bushing was in place and lined up right. All the bolts was torqued to spec.

I am not sure on the torque converter even though it is new and i did somewhat test it with air pressure.

It still poured out after checking all of this. I am going to do a pressure check today on the line pressure and EPC pressure. I am wondering if it is getting to much pressure and pushing past the seal. It is not a pressure seal.

 

A 2000 expedition converter highly unlikely that it would have a torque converter drain plug. Ford eliminated them in 98 or 99. As much as it sucks. I'd pull the trans again and pull the pump out. As stated above. Check the paper pump gasket. Check the rubber pump seal (the big O ring around the pump body). Then check the converter seal. It is also possible to have the pump bushing come loose and push forward and actually push the back of the converter seal.

 

This leak dogged the 99 4R70w I built, for me it was a slow enough leak(it only leaked out less than a quart in 6 years), but kept the trans wet all the time. It was the pump seal, most likely the paper one but I couldn’t rule out the O ring. I replaced them(and the converter seal) when I sold it.

 

Can you post some pictures of the input shaft side of the trans with the converter off? And a picture of the converter installed when the trans is out?

 

Yes i will do that later this week when i get a chance to pull it back out.

i did the pressure test and all was perfect.

I even tried the old torque converter and still pouring. I got thinking about everything and when i pull it out i am going to look for a crack in the pump housing. I have just ordered a new pump so this better fix it. I will still dissect it until i find the cause.