alsatropine

iTrader: (2)

I have a 04 F150 5.4 with the 4r75w . When cold it shifts out great. As long as I maintain highway speeds it acts normal. As soon as I come to a stop and start to go again , it'll go 1-2-3-4 then neutrals out. I replaced the valve body and the E Clip and snap ring are not broken. This unit was rebuilt a little over a year ago. I had the servo pin upgraded to the Sonnax pin. There is no trash or metal in the pan at all. Looks brand new. I hooked it up to the snap on and no transmission codes. The PCM is commanding fourth gear but like I said it neutrals out after warm. Solenoid s have been swapped out three times with no change. What are your thoughts before I have to pull the tranny again..

RLXXI

Trans tech at the dealer I worked at had the exact same problem with one of his builds, the case was cracked and allowed pressure to bleed off when warm, fixed it with a new case.
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alsatropine

iTrader: (2)

If the case was cracked, wouldn't I be loosing transmission fluid? I haven't seen any visable cracks. The only other idea someone shot at me was the seal around the bottom of the servo piston was cracked or torn. I forgot to mention when I did pull the valve body, I did have fluid seeping out from the bottom of the servo piston.

RLXXI

In the case of my fellow tech, the crack was internal allowing pressure to bleed into other parts of the tranny. Not leak out.

All those intricate cuts in the case are critical for fluid to channel where it needs to go, various servos, clutch packs, shift solenoids etc.. if that case is faulty it screws everything up.
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alsatropine

iTrader: (2)

Gotcha. I understand now. If the servo replacement doesn't fix the issue, I'm pulling the tranny next Sunday and going back to the builder who built it and being torn down and inspected.

RLXXI

We never visibly found a crack, we called the Ford hotline and their trans tech told us that if the bench air pressure test passed (obviously cold) but the trans failed when warm, it was the only possible explanation. Good luck.
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alsatropine

iTrader: (2)

Just an update. I replaced the 2-3 accumulator , spring, and OD servo with the updated Sonax OD pin. The servo and band looked fine before I pulled it. Something was up there but I couldn't find it on the OD side. Makes me wonder if the 2-3 accumulator had something to do with it. The accumulator I took out basically fell out, where as the new one I had to help it to get it bottomed out. Go figure. But so far so good!! Oh and on a side note, when you push the OD band over to set the servo pin, you might need some help cause it is a PITA doing it by yourself .Transmission runs like a champ now!!