Ford C6 transmission issue - doesn't want to drop into gear from park.

I've got a C6 in my Hudson. It's a junkyard trans, and I have no idea how many miles are on the unit.

I've got a Gennie shifter hooked up to it, and it has one of those universal Lokar dipsticks. The trans fluid is nice and red, no discoloration of any sort, and when the trans is good and hot, it reads at full on the dipstick.

Lately, an issue has come up. I haven't had trouble with it before. The trans has been in the car a year or so, and I've put about 3-4,000 miles on it since it's been in the car.

Sometimes, when I start the car and move the shifter from park into reverse or drive, the trans won't shift out of park. I can run the shifter through all the gears, reverse, drive, 2, 1, and nothing changes...it still stays in park.

If I shut the car off, and start it again, it will usually drop into gear just fine. Sometimes I have to do this 2 or 3 times.

The trans doesn't do this every time I start the car, probably about 1 in 10 times.

I've had no trouble with the trans slipping when I drive it, no missed shifts, no slow shifts, etc.

Any ideas before I pull the trans out? Perhaps the Lokar dipstick is giving me a false reading and the trans just doesn't have enough fluid? I was thinking perhaps it has something to do with the vacuum modulator, or maybe the trans just needs a rebuild? New bands? Obviously, I'd rather not pull the trans out just yet if I don't have to...

 

Check your linkage and make sure it didn't come loose .

 

Check. Not the linkage.

Any other ideas?

 

Anyone have an idea of what a typical C6 does when it's too low on fluid? Too full?

 

Not sure what a C-6 does, but a small Mopar trans behind a 273 and a T-400 behind a big block will slip when it's a quart to quart and a half down.

A trans shop recommended checking fluid level with engine running and the trans in drive.

The T-400 seems to check ok if the engine is running.
Parks ok and it doesn't seem necessary to put it into drive.

I'd give both methods a try with the C-6 and see what you get.


Fwiw - the T-400 checked full with engine off and a quart and a half down with engine running.

 

Typically, a C-6 will not pull at all if the fluid is very low. I have seen them not go, immediately into gear if the fluid is much more than a quart low. They will also go into, and out of gear when the fluid is sloshed to the side of the pan when making a sharp turn, when the fluid is low. I may be wrong, but your problem doesn't seem fluid level related. There are guys here on the H.A.M.B. who know trannys and will be along soon to diagnose your problem.

 

I'll try it with the trans in drive. I wonder if perhaps the "universal" dipstick isn't very universal and is giving a false reading?

 

It needs fluid. At around 1 1/2 qts low it will not go into any gear. Add some fluid and all will be fine.

 

hmmm. I'll give it a shot.

 

C-6 had a problem we called Morning Sickness. After sitting over night the Converter would drain back and not make pump pressure for a few moments. To be sure its actually not lincage, next time you start it and does not go into gear leave the shifter in gear and push the car to be sure it's out of Park. It will probably roll just fine. It's from age and the internal check valve is leaking. No big Deal really. Just leave it in gear until it pumps the fluid back into the converter and then go drive it.
The Wizzard

 

Did adding fluid fix your problem?