5R55W trans mystery...

[Mussin]

I have a 2002 mounty and the trans went out (3rd gear band broken, 5r55w) The guy who rebuilt my trans had the servo bores bushed and had to buy another intermediate servo, the silicone was tore as well. Well new clutches, bands, servo and everything is back together and in the car. Here's where the strange part comes to play. When cold the trans operates fine, after 15minutes of driving it slips from 3-4 gear. It revs about 500rpm then engages. No od light flashing, no check trans light. However it only "slips" when pressing the pedal lightly, like when in traffic behind a slow car. If you accelerate through the gears 1/2 throttle or so or WOT it wont do it and shifts fine. It only shifts when putting around. Its almost like there isn't enough line pressure to make a firm shift. We tried another Solenoid pack that I know is good and it did the same thing???

What else can we check? We are scratching our heads here... THANKS

Jeremy

 

[BrooklynBay]

Adjust the bands. A new tune might help too, but try the band adjustment first.