I’m having an issue.I rebuilt my tranny over the winter. All new clutches on all gears. All new shift solinoids in valvebody. New internal wire harness.I put the tranny back in the truck. After a couple days of local driving the truck did great. Smooth shifting in all gears. So decided to take the truck to work which is only about 32 mile drive. About half way into the trip the truck started to act real funny. Speeding up, losing torque, then speeding up and actually slipping. Thought maybe was low on oil so added oil to bring back up the lvls. That did not do the trick. Started driving again and after a couple hundred yards it slipped back into neutral. Pulled it into a parking lot let it sit about 20 mins. I tried it again went right into first no problem, go to take off and started slipping again. Checked fluids was a quart and a half low. Topped that off to were it read just above full while truck off,and lvl went down while running.tried truck again and went right into gear no problem. After a couple minutes running at idle went to put truck in drive and nothing at all no forward no reverse. Turn truck off let it sit 20 minutes. Start it back up and goes right into drive and reverse no problem. Go to take off and it drives for a hot sec then starts to act like in neutral. What did I do wrong or is there something I need to recheck to see if it let go. The pump is brand new and was working as it should. But did reuse original torque converter. Thanks for reading my rambling.

 

All of the clutches are in the pan. When you start the engine, the clutch material gets sucked up into the filler, stopping the flow of fluid. Transmission slips and you turn the engine off. Clutch material goes back into the pan when the fluid drains out of the filter. Now the question is did you ruin the clutches by running it low on fluid or are they ruined from a mistake made on the rebuild?

 

My money is on a torn/ nicked teflon ring or piston seal.

 

now how would I locate the torn ring or seal

 

by taking it apart, as that is most likely what will be required.