C4 troubles

I have a C4 behind a 351C in my F 100 and it will not up shift,I can shift it manually.This thing has been sitting for about 15years,just backing in an out of the garage is all.Took it out for a trip around the block and would not up shift.Could there be something stuck or froze up from sitting and is there a fix with out pulling the trans? I hope some one has a fix so I don't have to pull the fucking tranny.I'm getting to damn old to crawl under the truck much

 

Check for vacumn at the modulator valve.

 

the diaphram probably dry rotted, this guy has the right idea. if you have good vaccuum at the modulator, replace it.

 

Replace the modulators AND the rubber hoses that connect it to the vaccuum source ...either the carb but probably the manifold..

 

Thanks,I forgot all about the modulater

 

let us know how you do.

 

If you pull the vaccum hose of the modulator and fluid comes out the diapham is blowed replace modulator. If you can manual shift the transmission you have a stuck govenor. you will have to pull the tailshaft off to get to the govenor and take it off and check the weights to see if they are stuck.
Also make sure your not hooked to ported vaccum. hook to manifold vaccum.

Hope this helps

kcl

 

My bet is the governor

 

The Govenor would not cause the symtoms he's having. Its the vacuum modulator or the valve sticking behind it but my bet is the vacuum modulator and or vacuum lines rotted or come loose.

 

I'd almost bet as long as it has been sitting the valve body will need to come off. I just did the C-4 in the '66 because it wouldn't shift

 

When you change the modulator make sure you do not loss the pin behind it. Sometime they will fall out when the oil starts coming out of the hole.