4R70W Front Seal Leak After Rebuild.....
Junior Member
Joined: Jul 2024
Posts: 3
Likes: 0
rebuilt my 4r74e with new everything and gushing fluid past new front seal
Just checking back in with this project....I've had the transmission out, and back in numerous times now. Checked everything. New sealing rings on the pump, new bushing, new torque converter, new front seal, new flex plate AND a completely rebuilt unit. When I start it up, it gushes fluid from the inspection hole in the bell housing. I have not a clue. I'm at the point now where I've got $800 in the rebuild, and I can't drive it so I'm going to have to strap some kind of container to the bottom of the bell housing to catch the fluid (@ $5/qt), and just move it out of the driveway and out of everyone's way. It saddens me greatly, but it seems no matter who I call, no one... and I mean no one.... can seem to tell me WHAT will make a transmission gush fluid right past a new front seal...in Park, Reverse, Drive, Neutral...doesn't matter. As an Engineer myself, I'm truly shocked that I get the same answers over and over again: Front seal, pump gasket, front bushing. That's it. There is SOMETHING that can cause a tranny to put pressure against that seal that it was never intended to hold, and whatever that 'thing' is, it's happening here. When I find out...IF I find out.... I will post the result in detail. In 35 years of wrenching on cars and trucks, I've never seen a front leak this bad that didn't reveal a bad seal upon removal. Ever. I'm no professional mechanic, but I know for certain this seal isn't supposed to have this kind of pressure against it. Stay tuned, lol.
Junior Member
Joined: Jul 2024
Posts: 3
Likes: 0
This is the seal I used. I have a 4r75e complete rebuilt with all new bushings and upgraded parts including the check valve. I have about 2500 flawless miles on the trans and it started pouring fluid out of the bell housing in traffic yesterday. It did the same thing pulling my camper before rebuilding. So frustrating
Senior Member
Joined: Apr 2023
Posts: 4,261
Likes: 1,382
From: Near Salt Lake City
If you watch that video from performance transmission (read post 19 again)
He talks about the grey seals being the updated seals and the black ones failing IIRR
I used to see our trans guy stake them in and seal the edges
There is fluid pressure behind that seal (hence the retainers) (used in some applications)
He talks about the grey seals being the updated seals and the black ones failing IIRR
I used to see our trans guy stake them in and seal the edges
There is fluid pressure behind that seal (hence the retainers) (used in some applications)
Junior Member
Joined: Jul 2024
Posts: 3
Likes: 0
If you watch that video from performance transmission (read post 19 again)
He talks about the grey seals being the updated seals and the black ones failing IIRR
I used to see our trans guy stake them in and seal the edges
There is fluid pressure behind that seal (hence the retainers) (used in some applications)
He talks about the grey seals being the updated seals and the black ones failing IIRR
I used to see our trans guy stake them in and seal the edges
There is fluid pressure behind that seal (hence the retainers) (used in some applications)
Senior Member
Joined: Apr 2023
Posts: 4,261
Likes: 1,382
From: Near Salt Lake City
The Ford seals all came with a sealer on them IIRR
I remember our trans guy using aviation form a gasket on them too
Maybe get on his YouTube feed and ask him what to do or check
Do you have a caliper so you can accurately measure the diameter of the converter seal area?
I would compare that measurement with spec even if the converter is brand new
I remember our trans guy using aviation form a gasket on them too
Maybe get on his YouTube feed and ask him what to do or check
Do you have a caliper so you can accurately measure the diameter of the converter seal area?
I would compare that measurement with spec even if the converter is brand new
