Transmission slow to move

[LTZ C20]

Ok guys so hears a new problem. My 79 C20 is being a pain in the rear again. A lot of you know I put a new engine in. Well this morning I tried to leave my house, started my truck, put it in reverse and nothing happened. I revved it and it didn't move. Same for being in drive. About 15 min ago I decided to try again, in reverse I won't roll unless I give it gas, about 1000-1500 rpm. In drive I had it between 1500-2000 before it would slowly start to roll. I could rev it in drive and it won't move. I checked my fluid and it's clean and doesn't smell burnt. My shifter linkage is working properly.  It's an automatic turbo 350 and it's always run good for me but now doesn't wanna get out of it's own way. Any ideas? Thanks.

[achevy1978]

im in the middle of a th400 rebuild....it was doin the same thing...when i got it apart the clutches and steels looked fine, valve body bolts seemed a little lose and when i took the pump apart the gear had scored the stator half...so im thinking between the loose vb and scored pump maybe a loss of pressure making it slip....dont know

[VileZambonie]

Ensure the fluid level is correct. If OK drop the pan and check the filter. Then check the operation of the manual valve (set your brake and chock your wheels -don't run yourself over).

You said you recently put the engine in? Have you driven it since? The converter is bolted to the flex plate right? Next step do a pressure test.

[LTZ C20]

Oh dang it. Well yesterday I replaced the pan seal cuz it was leaking, never had a problem before that either. Even after I replaced the pan seal over a year and a half ago. I topped off the fluid after the reseal. Is it possible that it had an air bubble and now the fluid level dropped causing it to slip? As for checking the manual valve I have no idea wat that means. Haha. I'm not so smart when it comes to transmissions. The flexplate is bolted to the converter and as in resent new engine that was 2 months ago. I've been driving it for the past 2 months with no problem. Now all of a sudden. Pop, the darn thing quits.

[VileZambonie]

Ensure the filter didn't fall off and is correctly installed (o-ring or gasket?) The manual valve is connected to the shift linkage and controls the fluid flow through the valve body based on shift range.

[LTZ C20]

Alright guys. I've decided to pull my old turbo 350 out. I'm going to be replacing it with a 500hp capable, 700R4. Got a buddy at work with a 700 and another buddy at work who's gonna build it for me. I'm not very good with transmissions but he is great and he's built hundreds. When it's all done should be about $1500 project, but a new trans capable of handling 500 hp. I'm only putting out about 360 hp though so it's not gonna break on me. Also leaves me some room if I squeeze a little more juice put of this motor with some upgrade or toy down the road. Can't wait for my tax returns so I can get back on the road! will post pics of new trans when it's going in and all done.


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