My c-4 transmission woes

garyscholl · Sep 3, 2009

I have a 79 ford pick-up with a c-4 transmission that won't go into gear. At first it would only shift manually to 1st and 2nd but would not go into 3rd only rev. I took out the vavle body and all but 2 of the servos were stuck. It had been sitting. I clean everything up and got them all gliding nicely. Noe it won't go in gear at all. I think it is low on fluid anything I am missing. Help

av bronco · Sep 3, 2009

probably need to run pressure checks, One of the 50 or so times I thought I broke my c4 when I ran pressure checks the drive line was spinning= broken axle. Check out the C4 section on ford muscle.

Viperwolf1 · Sep 3, 2009

You're missing the rest of the fluid. Top it off before doing anything else.

av bronco · Sep 3, 2009

av bronco said:
probably need to run pressure checks, One of the 50 or so times I thought I broke my c4 when I ran pressure checks the drive line was spinning= broken axle. Check out the C4 section on ford muscle.

Oh yeah, one more thing, check the dipstick;D

broncnaz · Sep 3, 2009

Thats a rareity most 79 pickups would have a C6. Either way all the advice is the same.

77BRONKOTN · Sep 4, 2009

Check the vacuum modulator.

garyscholl · Sep 4, 2009

I have refilled the fluid to the approrpiate level and it onlt goes in reverse.

garyscholl · Sep 4, 2009

Oh and I did do a vin search and the truck did come with a c-4

Viperwolf1 · Sep 4, 2009

garyscholl said:
I have refilled the fluid to the approrpiate level and it onlt goes in reverse.

I suspect the forward clutch is not working. Could be bad rings on the stator, worn out clutches, or bad seals in the clutch drum. How did the pan look when you had it off? Was there much junk in it? Another possibility is that you did something wrong in the valve body.

garyscholl · Sep 5, 2009

When I took the pan off and cleaned out the valve body it was dirty. There was sediment in the pan, coating the bottom. No chunks of anything. I did not remove all the parts in the valve body only split it and freed up, cleaned and lubed all moving parts. Plus the symptoms were the same BEFORE I took the valve body out. As for bad seals or clutches or bad rings in the stator does this mean I am looking at a rebuild?

av bronco · Sep 5, 2009

You can drop the valve body and pressurize the drums and band to see exactly whats going bad, I did a google serch on C4 pressure checks to find out what ports to hit with air.

garyscholl · Sep 6, 2009

Ok I'll try that

Viperwolf1 · Sep 6, 2009

Here are some good instructions.

garyscholl · Sep 7, 2009

Ok, I dropped the valve body, This time diassembling it completely and cleaning it thoroughly. Used my compressor to pressurize the ports indicated on the diagram. After a few trys some yucky looking fuild seeped out the I could actuate the servos and hear them and see the bands move. The forward clutch port is the only one that did not produce a thud or click every time. Is there aspecific pressure to actuate that clutch? Or does the lack of sound mean I am screwed. I have put it all back together, but did not pick up the fliud yet. Does anyone have any ideas. By the way the pressure used was about 75 psi. I tried as high a 100 in the forward clutch and nothing. ???

Viperwolf1 · Sep 7, 2009

I use about 40 psi but I don't think you can hurt anything with 100. The forward clutch is hard to hear but if you place your hand on the shell behind the front band you should be able to feel it. If you can't the forward clutch is not working and it's time for a rebuild.

garyscholl · Sep 8, 2009

OK Thats What I was afraid of. I guess I will refill the fluid and test it and if no improvement then rebuild time. Thanks for your help.

My c-4 transmission woes

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