2007 F150 4X4 Low and Fluctuation of Pressures 4R75W

[CP]

Make

Ford

Model

F150

Year

2007

Miles

188000

Engine

5.4

Transmission was rebuilt completely several months ago and worked fine. Then one day there was noticeable slippage in 3rd gear. No codes come up, so checking line pressure. Found to be low and fluctuating. So checked EPC pressure and also found low in forward gears, a little better in reverse. Checking these at idle. When I put into gear, the pressure may jump up higher, but slowly fall back and the more you run it the lower the pressures get. Unhooked the connector to the transmission and pressures were higher. I’m wanting to check all I can before, lowering the pan. Anyone have ideas, or this something you have seen before? All the solenoids were replaced when the rebuild was done with Ford parts. Oil smells okay. I can get it to slip in other gears also, besides 3rd. Reverse seems okay. Thanks for your help!

 

[bp042665]

i have seen this with a internal cross leak was a updated valve body Install with rebuild if so you can try to double up the upper valve body gasket it has fixed a few for my shop

 

[CP]

in reply to what questions i had, and things I wrote above, the oil smelled a little burnt, so dropped the transmission and am in the middle of carefully looking for anything that may be the cause of low pressure. Haven’t found anything yet. We found a transmission out of an 05 that has 6000 on a rebuild. Will that work in an 07 ? Anyone know?
thanks