Auto gearbox wont come out of 1st

[J Bell]

I have a 1979 Corvette with a 3 speed auto. Today I changed the air filter and the recover covers to something more shiny but since then the car no longer shifts out of 1st gear. I cant imagine how replacing those components could affect the transmission but it must be something I have done as it was working perfectly before today. Is there anything I can look at? All vacuum lines appear to still be attached, although there is a metal vacuum line running down the back which is loose and rattles around but was also loose before I changed things. Any advice appreciated. Thanks

 

[johng]

Sounds like your modulator valve vacuum connection has come off, that is the metal line that runs down to the gearbox. Happened to me once.

 

[J Bell]

Sounds like your modulator valve vacuum connection has come off, that is the metal line that runs down to the gearbox. Happened to me once.

Thanks, Im hoping thats all it is, just waiting to borrow some ramps so I can get under it and check. Just typical the first time the sun comes out and it starts falling apart!

 

[Chuffer]

Thanks, Im hoping thats all it is, just waiting to borrow some ramps so I can get under it and check. Just typical the first time the sun comes out and it starts falling apart!

Vacuum connection definitely the best starting point as Johng said , or the modulator might have gone bad . They are not expensive to replace in the grand scheme of things . Have you checked the transmission fluid level following the proper procedure ? The TH350 is very sensitive to low fluid levels .

 

[Oneball]

Thanks, Im hoping thats all it is, just waiting to borrow some ramps so I can get under it and check. Just typical the first time the sun comes out and it starts falling apart!

As you’ve been playing around the carb I’d check the other end of the vac line first.

 

[J Bell]

Vacuum connection definitely the best starting point as Johng said , or the modulator might have gone bad . They are not expensive to replace in the grand scheme of things . Have you checked the transmission fluid level following the proper procedure ? The TH350 is very sensitive to low fluid levels .

I believe it was okay, it was running perfect before today but I'll double check the level in the morning, thank you