Ouch! I think I lunched my C6 on my '82 F150. The tranny only has about 6K (TCI rebuild), but I think I got it overheated on a trip to Charlotte. The fluid (Redline) smells a little crisp, but the color is still good. It started when the truck didn't seem to want to downshift going up a long grade. We stopped for some dinner, then it seemed to work fine the rest of the way home. Now, however, it doesn't want to shift until you're either at about 4200 rpms or if I back off the throttle. Any suggestions, or is my tranny toast??

Slik

 

try changing the modulator. unless you pulled it hard for a long time without downshifting you probably did not damage the tranny.

 

Yeah, I agree that its the modulator valve. Only cost about 10 bucks and real easy to change. Good luck.

 

Got my modulator valve for $7.94 and replaced it. When I pulled the vacuum hose, I got fluid out of the hose. When I pulled the modulator, it drained about 2-3 quarts of tranny fluid (is this normal?). I installed the new modulator and did some adjustments and it seems to be working fine. It shifts at different points and the shift points aren't as hard, but it seems to be shifting correctly.

Thanks,

Slik

 

Oil in the line indicates the modulator was leaking. You fixed it.

 

Some of the modulators come where you can adjust them so itll shift harder or softer and kinda fine tune shift points. Just look in the end that the hose connects to and see if theres a place for a small standard or (flathead) screwdriver. If so then thats how you tune it.

 

Slik, what you found is normal when the modulator valve fails. The vacuum on the hose going to the valve literally pulls the trans fluid right through the vacuum hose right to the motor to be burned in the engine. People who have an unexplained loss of trans fluid ( no visable leaks ) and erratic shifting should check their modulator valve because it could be bad.