No shift TH350

[montezuma]

I have a 79 monte with a 350/th350. Today I went for a ride, after a few minutes the car would no longer shift correctly. The car will not shift into third and will only go into second on deceleration. any body out there have any ideas on whats going on?

 

[DRIVEN]

Check your vacuum modulator and the vacuum hose to it.

 

[montezuma]

That was the first thing i checked and everything looked fine. Any other ideas.

 

[DRIVEN]

Any chance that your kick-down cable is stuck in the extended position?

 

[montezuma]

The cable was removed when the trans was rebuilt

 

[megaladon6]

The cable was removed when the trans was rebuilt

when was that?
have you checked your fluid level/condition?
is the shifter in the right position?
have you done ANY other work on the car?

 

[montezuma]

The trans was rebuilt years ago and was working fine until yesterday afternoon. The problem began when i was headed home from a grocery store. The fluid level is fine the condition of the fluid is also good. I also checked the vacuum diaphragm and vac line. The trans seems to shift from 1st to 2nd only on deceleration and not into third at all. I can manually downshift into first but it will not upshift with the shifter.

 

[DRIVEN]

Sounds like it's internal. You were planning on an overdrive upgrade anyway, right? :lol:

 

[montezuma]

Buying a new trans would be my last resort. Any body out there familiar with the th350s internals?

 

[DRIVEN]

I've rebuilt a few of them. Your problem is probably in the valve body since you mentioned no slippage and it will occasionally go into all gears. Likely some small debris hanging up one of the spool valves. If you have access to a transmission flush machine, I'd try that first. If that doesn't clean up the problem you can get another valve body and swap it out. Let us know how it turns out.