Hi guys, New to this forum. Searched for an answer to my problem and can't find an answer. Here is goes. 2004 F150 NBS 5.4 with the 4R75W tranny. Rebuilt a little over a year ago at 207000 miles. I'm at 219000 miles now. I'm very mechanically inclined, just not super smart on transmission issues .Here's the symptoms. When I first start off in the morning or the transmission is cold, it shifts great. As soon as it warms up I loose OD.I can most of the time manually get OD to catch but at a little bit higher RPMs when changing gears .If I let it slowly swap gears I hit ODands it goes to neutral. It's almost like the fluid thins out and starts bypassing somewhere in the valve body. That's the only part I didn't swap out when the transmission was rebuilt. I did have the sonnax cure kit installed on the rebuild. Does this sound like a valve body issue to y'all? I've read documents where the piston wears out the valve and starts bypassing the OD. I've checked the OD servo clips and all are intact. No other issues with the truck but that .Thoughts?

 

Just a little update. Was finally able to break everything down yesterday. I replaced the 2-3 accumulator and spring (which was shot) and also went ahead and swapped the OD servo and installed a new Sonnax OD servo pin. I'm telling you right now trying to set the OD pin to the OD Band was a major headache with just one person. If you ever have to do this make sure you have a helper, it woudve gone much faster. Keep in mind I had already installed a remanned valve body three weeks ago which didn't help. When I pulled the OD servo, the band looked like it was in place where it should 've been and the servo seal itself looked good, but I guess there was a bad spot somewhere. Who knows. It's done, fixed, and another headache I don't have to deal with anymore for the time being. I would like to give Darrin Burch a major shout out for his guidance and new parts. If you ever need a very knowledgeable guy on transmissions, this is your guy, not to mention if I ever need a complete transmission, it's coming from him.

 

 

What did you replace your transmission with? Used transmission? Rebuilt transmission? Remanufactured transmission? Who did the work? You or a shop?