5R55E Lost Drive, then all gears (1, 2, & R): Diagnosis, Repair & Parts

[avid]

Here's the situation:

(1998, 4.0L, 4wd, 5R55E Auto, 230K miles)

I had gotten home from a 1200 mile drive two days before transmission failed. At the time it failed I was driving it for the first time since the trip and was about 6 blocks from home. I was turning out onto a busy street from a stop sign and gunning it pretty good to get in-between traffic and I suddenly lost (Drive). The engine was still revving, but the truck was no longer moving. After some panic I downshifted into (2) and the truck started moving again. I continued to the store, and I think I used both (1) and (2) on the trip there and home. I can't recall for sure but it's possible (Drive) worked on the way home.

I made it home but eventually lost all drive, even in (1) and (Reverse). I had seen no leaks of fluid at any time, but added some fluid (don't recall how much- probably a quart or two) just in case and it didn't seem to make any difference. After some searching of those symptoms on this forum I figured it was probably time to rebuild the transmission. I had some problems removing the rear drive shaft as part of the process of removing the transmission so the truck sat for quite a while.

I finally got the transmission out and disassembled, and I didn't see anything that looked like a problem. So I'm thinking what: the Valve Body and/or Pump is failing? Does the Torque Converter fail and what does that look like?

Here's something else I didn't notice until I got the transmission removed: it was a previously "Ford Remanufactured" transmission. (I got the truck in 2016 with 180K or so miles on it.)

Thoughts?

 

[pentode]

I'm not an auto trans expert so I'm brainstorming here, but do you have it torn down enough to inspect the pump?
Might be a bit late, but did you check with a scan tool for transmission codes?
I'm shooting from the hip, but it does sound like you're dealing with a loss of pressure - I wouldn't expect several solenoids to go bad all at the same time, so I would be thinking either electronics or, possibly torque converter. If the seals go in the torque converter you could end up with a no-drive situation.

 

[avid]

I'm not an auto trans expert so I'm brainstorming here, but do you have it torn down enough to inspect the pump?
Might be a bit late, but did you check with a scan tool for transmission codes?
I'm shooting from the hip, but it does sound like you're dealing with a loss of pressure - I wouldn't expect several solenoids to go bad all at the same time, so I would be thinking either electronics or, possibly torque converter. If the seals go in the torque converter you could end up with a no-drive situation.

Thanks for the response, Pentode. Yes, it's completely torn down now. I didn't check for codes but the check engine light didn't come on.

All of the mechanical parts, bearings, gears, everything visible looks fine to me. I'm a complete novice with transmissions, but just mechanically nothing looks damaged or even worn.

I think the key symptom was that the failure was basically sudden and there were no symptoms before that. Just gunning the engine to get into traffic and it failed. That makes me think torque converter and/or pump. But again, I'm a complete novice with transmisison.

 

[pentode]

Agreed, it does seem like the rapid, but not instantaneous, failure feels more like mechanical than electronic.

Have you looked at the pump itself?

 

[avid]

Outside of the pump.

 

[avid]

Have you looked at the pump itself?

Yes, as much as I can with just the basic disassembly in the service manual. (See photos in previous post). The large gears seems wonky but also like maybe they're supposed to be like that.

I saw an old post from RonD and he suggested always replacing the pump when the transmission is opened, so as long as I can find one I suppose I will do that.

If rebuilding ALWAYS replace
pump
one-way clutches(sprags)
OD drum
Most places don't do this and trans will fail in 18months usually