turbo 400 sometimes sticks in first sometimes not!!!???

[Contractor Ray]

Sometimes the trans won't shift out of first. I have to stop and put it back into park, then drive and try again till it starts shifting ok. Also, if it won't upshift I can shift it to second and it shifts right away. When I put it back into drive sometimes it works and sometimes it falls back to first.
When it's working good it seems to shift ok for an old work truck. I'm pretty good mechanically, but have very little trans experience. I googled like he'll, but I couldn't find any issues similar to mine.
Thanks in advance.

 

[Honky Kong jr]

Sometimes the trans won't shift out of first. I have to stop and put it back into park, then drive and try again till it starts shifting ok. Also, if it won't upshift I can shift it to second and it shifts right away. When I put it back into drive sometimes it works and sometimes it falls back to first.
When it's working good it seems to shift ok for an old work truck. I'm pretty good mechanically, but have very little trans experience. I googled like he'll, but I couldn't find any issues similar to mine.
Thanks in advance.

Welcome to the site. What does your fluid look like. Your modulator could be shitting the bed.

 

[twinturbo427]

My first thought is the governor is sticking or the plastic gear has worn out. Easy fix either way.

 

[Contractor Ray]

Thanks for the quick reply guys.
The fluid level is good. I added some Lucas to it when it started happening last week. I pulled the module earlier and checked for vacuum pressure and a leaking diaphragm. both serm good. I just pulled the governor and the gear looks good. Also the weights seem to move easily and the shaft Inside Moves when the weights move. So I think that looks good too. like I said I'm pretty green when it comes to trannys.

 

[Honky Kong jr]

Thanks for the quick reply guys.
The fluid level is good. I added some Lucas to it when it started happening last week. I pulled the module earlier and checked for vacuum pressure and a leaking diaphragm. both serm good. I just pulled the governor and the gear looks good. Also the weights seem to move easily and the shaft Inside Moves when the weights move. So I think that looks good too. like I said I'm pretty green when it comes to trannys.

Did you try manually shifting it threw the gears?

 

[Contractor Ray]

ya. it always goes into second if I put it in second. When I put it in drive sometimes it's fine. Sometimes it goes back into first.

 

[74 Shortbed]

Sounds like crud in the VB..

 

[Honky Kong jr]

Also I meant condition (color) along with level. I should of elaborated.

 

[Contractor Ray]

Normal. Red. sweet smell.

 

[yevgenievich]

There used to be a bit of a mad method on clearing up crud in a th350 by slamming in reverse while 5-10 mph or so on gravel road. Someone would need to back the theory up that it might work on th400 and also probably really a last resort type of a thing.

 

[Honky Kong jr]

There used to be a bit of a mad method on clearing up crud in a th350 by slamming in reverse while 5-10 mph or so on gravel road. Someone would need to back the theory up that it might work on th400 and also probably really a last resort type of a thing.

I believe that is to force full mainline pressure threw...we used to unhook the VW automatics TCM putting it in limp which then runs full line pressure threw the valvebody and would take care of sticking solenoids. I know not the same thing but what your suggesting is the same principle.

 

[yevgenievich]

That is correct. I had forgatten what exactly it did, but line pressure increase it was.

I believe that is to force full mainline pressure threw...we used to unhook the VW automatics TCM putting it in limp which then runs full line pressure threw the valvebody and would take care of sticking solenoids. I know not the same thing but what your suggesting is the same principle.

 

[HotRodPC]

I'm going to suggest, pull the Vac Mod, then make a hook with a piece of wire and pull the Vac mod valve out. Look for gouges, clean it up, lube with vaseline and reinstall. See if that does it. Next to check is the governor but that's been suggested already. If it's not the easy, as Art said, some gunk in the VB namely the manual shift valve.

 

[Contractor Ray]

I'm going to suggest, pull the Vac Mod, then make a hook with a piece of wire and pull the Vac mod valve out. Look for gouges, clean it up, lube with vaseline and reinstall. See if that does it. Next to check is the governor but that's been suggested already. If it's not the easy, as Art said, some gunk in the VB namely the manual shift valve.

I'll give that a shot with the mod valve. Already checked that and the gov, but I didn't pull the valve out of the mod. might just replace it. pretty cheap. thanks guys!!!

 

[HotRodPC]

I'll give that a shot with the mod valve. Already checked that and the gov, but I didn't pull the valve out of the mod. might just replace it. pretty cheap. thanks guys!!!

Yes, it's common for peeps to cheak the vac mod when having symptoms, but they don't pull the valve out and check it. Modulator can be good as gold but if the valve is hung up it's going to have symptoms of bad modulator.