I just put my newly rebuilt 904 back in my car and it worked great for a couple short drives and then it stopped shifting into 3rd gear in drive or manually. I have tried to adjust the kickdown but hasn't changed anything yet. If someone has had this problem before or any advice I would appreciate some help. All I can think is something is messed up in the valve body but not sure what. Thanks for any help

Does Reverse work OK?

About 6 years ago I had the exact same issue with a newly rebuilt 727. A few days of driving I lost 3rd gear. I talked to the guy who rebuilt it, he was nice enough to come out to my house and drop the trans pan.He seemed to know exactly what the issue was.A snap ring had popped out for an accumulator piston that was for applying a band to hold somthing or other,basicaly so it would shift into third.Nothing was damaged he just popped everything back together and it has been shifting fine. He told me this was common on a rebuild that the new snap ring may pop out somthing in the way it heat cycles or sets.It might be worth a pan drop and a look-see.

yes reverse is working great. Actually today I took it out again and it shifts into third fine until it warms up and the engine and trans only get to 180 degrees. Not sure why I lose it after it warms up?

hi
have you rechecked your fluid level in NETURAL ON LEVEL GROUND ?

what did you use for fluid ?

I had a simular problem. lost third about 200 miles from home. I removed the valve body, tore it apart, and found one of the fluid channels inside had cracked. Some brake cleaner cleaned the valve body and some JB weld epoxy fixed the cracked fluid channel. The repair actually got me home and even lasted the month or so until I replaced the valve body.

checked fluid, its ok, took out and drove in drive and watched the temp come up and then when it got to normal operating temp it started slipping out of third gear again