2007 F150 4X4 Low and Fluctuation of Pressures 4R75W

CP

Full Member
Joined
Jan 5, 2007
Messages
79
Points
8
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

transmission guy
Joined
Nov 26, 2012
Messages
802
Points
28
Location
Iva South Carolina
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

Full Member
Joined
Jan 5, 2007
Messages
79
Points
8
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
 

CP

Full Member
Joined
Jan 5, 2007
Messages
79
Points
8
Just an update and more questions.
Got into this transmission and found two clutches bad, probably from the low pressures we had. Sent away the valve body to get rebuilt and checked. Now have it all together and giving it a few test drives. Now what is coming up is a code P0731 first gear incorrect gear ratio. Don’t come up right away, today I had to drive aboit 5 miles with several stops and starts. Line pressures are good now.. Any thoughts on why the code? New fluid, new Ford solenoids, shift and EPC. Very carefully put things together ,so really wondering what’s going on?
Thanks
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,914
Points
63
Is this the "original" trans, the one that was "rebuilt completely" several months ago? I suggest pulling the VB and doing air-checks on the clutches.
 

bp042665

transmission guy
Joined
Nov 26, 2012
Messages
802
Points
28
Location
Iva South Carolina
if the forward piston seal's got nicked or wasn't replaced that could be where the problem is coming from it is detecting a slip in first gear so it set's the error code
 
Top