I have an 84 F150 4x4 with 351W and 3-speed auto transmission (C6 I think?). Lately the transmission has started giving me trouble. When it's cold it doesn't want to go into gear easily (drive or reverse). I move the lever and it just sits there 5-10 seconds or more until I feel it actually go into gear. Sometimes revving the engine seems to make it go, sometimes moving the level back to park and then back to drive again. Not really a consistent pattern.

Once I can finally get moving, it will also pop out of gear frequently. This typically happens when I slow down to a stop sign. It goes back to neutral and I have to wait a second for it to go back into drive. Sometimes have to rev the engine to get it to go again. This will also happen when I slow down to go around a corner. It will go to neutral and I roll around the corner and as I straighten the wheels out again it will go back into drive.

All of the above seems to improve as the engine gets hot (maybe 10-15 minutes of driving) but never goes away completely.

I have checked the fluid level a couple of times and I think it's OK. I don't think it's leaking. Any suggestions on what to check next? I don't really believe there's a connection between power steering and the transmission but I swear that's how it's acting...

 

Sorry, dude, but I think your tranny is shot. The internal bearings and belts, ect. are probably slipping and there is not much that you can do about it. Yes, I'm sure your tranny is a C6, and depending on where you are at, you can usually find a good one form a private seller or junk yard for pretty cheap. There is a guy here close that has a good c6 with torque converter and good transfer case- he wants $350. I thought my c6 was going out, but it was just vacuum related on mine- fixed it for $20. Maybe you can get a professional diagnosis. Good luck.

 

Have you checked the oil level on the dipstick? It will kick in and out of gear when cold if the oil level is low.

 

Do you mean oil or transmission fluid? I think both are OK, but I'll check again when I get home tonight.

My understanding on the correct way to check transmission fluid level is: truck should be sitting on level ground, engine should be hot and idling while you check it. Should it be in park or neutral or does it matter?

 

Tranny should be warm, and the tranny should be in park with the engine running. The oil expands when it's warm, and that's the reason you check it warm, and it's also the reason why it will not drop out of gear when it's warm, since the oil level will rise barely enough for it to run(if that's your problem).

 

It doesn't matter whether you're in park or neutral. I would say that your ATF would have to be very low or none registering on the dipstick for your tranny to be slipping as bad as you say it is.

 

OK, the trans fluid was indeed very low. I put in over a pint before I could see anything on the dipstick. I'm guessing I've got a leak somewhere because these problems developed over about 2 weeks and it was working fine before that. However, I'm not seeing trans fluid on the driveway where I park. Is it possible I've got something that only leaks when the engine is running and the fluid is under pressure, while I'm on the road? That would explain why I'm obviously losing fluid but don't see it on my driveway...

 

If you are losing oil, you should see it somewhere, either dripping off the tranny, the rearend, or off the engine if one of the cooler lines is leaking up front. You will have to crawl under it and look it over.

The only other place the oil could be going would be through the modulator diaphragm, and then up the vacuum line into the engine. But if that were the case, the engine will smoke like a freight train.