Newbie to this forum. My son and I just finished(or thought we had) a 78 F250 4wd. We took on an initial test test and it was fine. He took it the next day on a 15 mile trex to get senior pictures with it and while in the way home last all gears. So that it is home and having done some testing and research here is where we stand.
The trans is a newly overhauled C6 done with a TCI master kit. It did get the shift improver springs for firm shifts for towing. So my research said to check pump pressure. While either cold or after atleast a15 minute break the pressures are at about 80psi for all but reverse which is 120psi, all at idle. I run it back and forth 6-8 times about 10 feet both ways and it lost all pressure but in park/neutral. Fluid is full and clean.

I am looking for some suggestions as to a direction. I am leaning more towards a converter and or pump as I know it didn’t seat properly when we first tried installing the transmission and had to try a second time. I know that we will have to remove the transmission but hoping we won’t have to pay for another full rebuild and just need some parts that we can handle.

Thank you
Ryan

 

I don't know enough to help but I feel your pain.

Last summer 2024 my wife was driving my 79 f150 pulling a heavy (5000 lbs) trailer on a camping trip in the mountains on a hot august afternoon and panicked because the water temp was climbing. I had told her to shut it down if it ever gets over 230 F water temp. Well she did and it heat soaked so bad by the time I got to it it was 260. I said what I should have told you to do, is shut ac off put it in neutral and let engine idle or hold rpms at 1500 for fan cooling until temp drops. I'm afraid the heat soak is what killed the trans because eventually it quit shifting until warmed up and I had it rebuilt-3 times this year, before the shop I chose, could get it right. The guys in these transmission shop I used seemed like they are used to working on modern computerized vehicles and I don't think they know the tricks like the old guys do. They had a good reputation in the past but it turns out the third time they rebuilt it they brought the old man in out of retirement to help. So far its good, fingers crossed. From my research I think you have something else messed up besides the converter. like servo seals or the wrong shift kit springs. The first two times I would get a soft or slipping 2 to 3 shift and it got worse after about 200 miles. The funny thing is on the way home from camping it shifted fine and then later had problems.

Did you do the rebuild or a shop? Can you elaborate on installing the converter incorrectly?

 

Ryan sorry for your possibly loss...So with the newly overhauled trans, did it come with ANY warrenty from the overhaul trans shop? Did you ask about any warrenty when you picked it up? I bet probably no warrenty, since you were doing the install yourself. That is how they cover their work on the internals.

But I would 1st reach out to the shop that rebuilt it and ask that warrenty question and ask them for some trouble shooting help. Befor you jump right into removing it. They might have a suggestion or two to try 1st. Also let them know your testing and research results. Good luck.

 

So we found the torque converter and front pump were atleast the start of the problem. My research and trans removal ground that the cheap torque converter was broken inside. Whether do to quality or my bad install as I didn’t seat it properly on our initial install. We also decided to replace the front pump gears as I noticed as slight imperfection from the converter first install. Test drives this past week seems like we got that problem solved but still feel something isn’t right so have a transmission shop taking a ride to get their opinion.