01 Transmission shifts fine but slips above 2500rpms

[DaveZyla]

Have a 2001 Sport Trac with tranny issues. Aprox 30,000 miles ago I replaced the valve body, gasket plate, and solenoids which included the updates. Adjusted the bands at that time. It hasn't had any issues until this week. Shifts through all gears fine but if your cruising down the interstate above 2500rpms or roughly 71mph) it will slip out of overdrive- rev up to roughly 3500rpms. Sometimes it feels like it's searching for a good gear. If you let up off the gas it will shift back into overdrive until the next time however it's quite frequent. You can actually feel the "slip" just before it happens.

We were actually 4 hours from home when it started- checked fluids. Drove it home 4 hours at 2500 rpms with no slipping. OD light never flashed. Again it shifts through all gears ok and only has issues above 2500rpms.

Any thoughts? First thought would be a pressure loss Or torque converter but why above 2500?

First post here- thanks in advance

 

[Fix4Dirt]

is it a shift flare? could be TC unlocking before shifting? how much go pedal are you using? just curious, mine takes a decent amount of throttle to kick out of OD

 

[DaveZyla]

is it a shift flare? could be TC unlocking before shifting? how much go pedal are you using? just curious, mine takes a decent amount of throttle to kick out of OD

Maybe dropping out of gear is a better use of words-
This happens well past shifting through gears and while at cruising speeds above 70-71 (or above 2500rpms). It doesn't matter if I'm going uphill, downhill or on level road. When I originally noticed it we were headed to a property we own 4 hours away. Travelled and hour at 69mph on highway through small towns ECT with no issues shifting, downshifting ect. It wasn't until I got on the interstate and set the cruise to 74 before it started slipping and would drop out of OD. It will catch the next lowest gear it can on it's own- mostly 4th sometimes 3rd. If I let off the accelerator it will shift back into OD. I kept decreasing the cruise until it stopped- which was 2500rpms. At this RPM it functions and downshifts as it should when needed going up hills ECT.

From a stop the transmission shifts through gears with no flare- I've accelerated through the gears pretty hard and still could not get it to flare between gears. Cruising I would say I'm about 1/2 on the pedal with plenty of room to go. Run it at 2600rpms and it will slip and drop back to 4th

The valve work was done because of flashing OD light not because I could tell there's an issue- I can tell there's an issue with no flashing ID light

 

[Fix4Dirt]

hows the fluid level/condition? what bout OD clutch? also not sure if this is a diesel thing of if X's have this too (my truck is warm by the time it hits the interstate), but iirc in diesels when theyre cold the ECT keeps them out of OD, probably X's dont have this, but just checkin!

 

[DaveZyla]

Fluid and filter was changed at the valve body, solenoid, gasket change.

Fluid on dipstick looked good- didn't want to pull the pan unless I had some thought in place. I do have the solenoids from the old valve body I could throw in.

 

[Fix4Dirt]

not sure, thats the only ideas i have could be solenoid pack... hopefully soemone else also has an idea!!!!

 

[DaveZyla]

Thanks- I think I'm going to drop the pan and valve body and take a look at the gasket, fluid and solenoids. The valve body gaskets are inexpensive compared to the alternative. Not sure what else to try- if I had shift flares, flashing OD light ECT I would say it might be done for- with none of that it appears the pcm thinks the tranny is operating as it should.

Someone with 5r55e knowledge might know more info and can chime in.

 

[Nctruckman]

How many miles are on the trans?

 

[DaveZyla]

How many miles are on the trans?

230,000 Is on the truck- we bought it used but supposedly had tranny work done at 130,000. It's had a well cared for life so I don't doubt it but without proof it's just talk.

I am- on the other hand- a cheap A$$ and don't want to replace the transmission unless I know it's toast. Part of that is I vowed each time after the last 3 swaps in various family/friends vehicles I wouldn't do it again- It's hard to pay someone to do something you can do but just don't want to