Hey everyone,

Trying to diagnose my 4R100. E99 V10 F350, 4WD. 238K miles, not sure if the trans has ever been out of the truck.

Every so often when pulling away from a stop sign the trans will not grab like it should, if I stay in the gas it will eventually lurch forward and then shift fine after that but if I pedal it I can usually get it to build enough pressure to engage 1st smoothly. Once it's in 2nd gear and above it behaves normally, no slipping or lurching. Once it warms up the frequency of the 1st gear slip decreases dramatically. It happens more often if I stop on a downhill slope. I did check fluid level.

Shortly after I bought the truck I had the feed bolts come loose, after following a guide on here I was able to torque them and get 17k additional miles out of this thing. Fluid was fairly brown at that time, not much on the magnet.

I did have one instance a couple months ago where every upshift was extremely harsh, like trying to snap the driveshaft, every gear. I pulled over, shut the truck off, restarted and that went away.

I pulled the pan/valve body again and found the bolts were still tight, fluid looked a little brown but not terrible, was not burnt. Also not much on the magnet. Figure the residual old fluid from the last service was diluting the new fluid?

I have hooked it to a snap on solus scanner but didn't see anything glaringly wrong. No codes at all. My instinct says the problem lies in the pressure control, I haven't hooked a gauge up to it yet but maybe a sticky valve or solenoid?

Or maybe it's just worn out and in need of a full rebuild. Thanks in advance for any input.

 

Pressure test is where I would do next. If you got the right pressure, then it's something internal.