Any ideas? Everything is hooked up as far as I can tell. After I start the car it goes into reverse 1 time and then no more???
Its a bop th400 13 bolt pan.
Thanks

 

how many miles are on it?

if there are a ton of miles, its probably just wearing out...also, TH400's are as common as...well...TH400's.

one look on my local Clist produced several 400's in the oldsmobile bolt pattern, the most expensive was like 300 bucks, and it had been rebuilt with a shift kit installed.

take it to a transmission shop.

 

you did check the fluid first didn't you? i had a 400 that i lost reverse and 3rd gear at the same time. it was many years ago since i did automatic transmission work but i was thinking that the 3rd and reverse clutch pack was the same one. are you noticing any trouble in 3rd?

X2 on taking it to a good transmission shop. they can tell pretty quick what it is.

 

Its a $450 Craigslist "rebuilt with shift kit" transmission Lol.
Modulator wasn't hooked up, got that sorted out still no reverse and is leaking fluid from dipstick tube and seal...chalking this one up as an expensive learning experience. Last stop is tranny shop if they say I need a rebuild I will....

 

Sometimes, if you have a decent 3rd gear on the car at all times, the problem could be a seal in the reverse servo that is going sour. The servo is the big round thing which is held on with six bolts when the pan is removed. Without quickly looking in my book, I can't quite recall if the 400 uses a separate seal/circuit to activate the reverse/high clutch. Pressure checks can usually disclose the problems if it is involving hydraulics. Hope this helps out. Regards, Howie

 

I just had a similar issue on my TH350. It was low on fluid. I added quite a bit of fluid and it went right into gear.

 

TH tranny seal problems seem to manifest themselves in this manner. Im having my TH350 rebuilt right now for not moving in any gear. Seals are dried out from not being driven enough. It is 40 years old though on the original everything.

 

Got it rebuilt, sacrificed 800 to the olds gods.
Law #1 of the Oldsmobile commandments...
"Thou shall do it right the first time."

 

Glad you got it sorted out Insom. I should have mine back this week. Im also having the rear end re-done. Posi seems to be skidding in turns. limited slip doesnt seem to be slipping.