I have a 1994 F150 super cab 5.8 liter 4x4 198,000+ miles. The transmission recently started slipping when in third gear and seems to just rev away and wont grab/engage until I let off the gas. It sometimes does this repeatedly before shifting hard and holding third and then shifts normally into fourth.

So a week or so ago I dumped in a bottle of Sea Foam, drove the truck ten or fifteen miles, parked it and replaced the filter and about 7 or so quarts of Valvoline High Mileage DexMerc transmission fluid.

That seemed to solve the problem (shift problems went away for a few days) but now its back again. I didnt notice anything out of the ordinary in the transmission pan or filter. The fluid was quite dark from the Sea Foam doing its thing.

I checked the fluid level and it appears to be at the proper level.

Supposedly the transmission was rebuilt a couple years ago by the previous owner for what that is worth.

I would like to get this tranny thing figured out before any more damage is done.

Do appreciate any guidance and hopefully I have given enough detail. If not please let me know. Thanks.

 

Please tell me you used Transtune, not Seafoam! Seafoam may effect viscosity. If you used Seafoam, contact the manufacturer by phone to see what they say. Most likely, they'll say drain, including the converter & refill.
Do error code scans for trans codes & read this: http://www.fordfuelinjection.com/files/Ford_MLPS.pdf

 

Also just use regular atf. The problem might be a sticking valve in the valve body, or possibly a loose connection, check the harness to the trans.

 

Try Lucas, it's awesome.

 

Agree!...Lucas is awesome!

 

Uh, yup, guess I used the wrong stuff (Sea Foam) instead of Transtune. Oops. So it looks like I get to drain the pan/filter fluid again along with the torque converter. Any tricks to changing the fluid from torque converter? I have not attempted that procedure before.

Any recommendations for when add the Lucas transtune product or anything else I should do? I havent checked the website yet and I am sure there are detailed instructions etc.

I will check the other recommendations including looking at the transmission wiring harness connections (once I figure out where they are...) I have also printed off the article regarding the potential electrical gremlins.

I appreciate all the info and help!

 

theres a plug you can access on the converter just rotate the engine till its visible from the hole in the bottom of the housing. someone else is going to have to step in and say whether or not the converter needs to be filled, or fills via the trans pump, i'm not really sure

 

On mine, there's a small vertical inspection plate to remove, then rotate the plug into view & access...

 

you dont have the 1-2in hole with a rubber/plastic plug couple inches back from there?

 

x3! save room for it on refill. Compatible w/ reg. ATF or Synth.