transmission help

[BIGjohns04]

alright lets see if anybody on here has any more ideas than i do... about 2 weeks ago i was driving my truck home and i had overdrive. never had slipping issues or overheating issues.. the trans is built billet input valve body triple disc converter so on and so on.... well i stopped at the local napa to get some oil to service it and when i was on my way home overdrive just vanished.. ive changed the o/d lock up solenoid the gov pressure solenoid and temp sensor.. ive taken it to 2 trans shops and they say it something electrical.. hooked up to a scanner and the truck calls for o/d the trans calls for o/d the desired pressure is right evrything is the way it should be but still no overdrive... it shifts through all the gears fine and even locks up just no o/d..... anybody have any ideas what could be causing this? i really wanna drive my truck since it was apart for 6 months and i only got to enjoy it for 1 week

 

[Big Blue24]

Probably need to put a pressure gauge on the OD test port on the side of the transmission and see if pressure is making it to the OD piston.

The easiest way to do this is to buy a cheap 100 psi sunpro oil pressure gauge setup at Autozone for $20 and run the line from the 1/8 NPT test port to inside the cab. The line is small enough to run right under the driver's side door, just be careful when you shut it.

At 60 mph, when it tries to shift into overdrive, you should see about 60 - 100 psi pressure. If you see something less, like 10-45psi, I'll bet the seal on the overdrive piston is ruptured. If you don't see any pressure, the solenoid or something else is not working right.