Hey All!

I have a 1993 F250 4X4 with an E4OD. I was rambling down the highway a couple days ago, on cruise, medium sized load of gravel in the box....and it just stopped propelling things along. Engined revved up when the drive let go but, otherwise, no noise, no shuddering, no noticed slipping. Just driving along one second, then nothing the next.

Coasted to stop thinking I'd some how lost the drive shaft or rear end it just stopped driving or released so suddenly. Moving the selector into any gear presents no noise and no observable effect on the drive shaft. It does cause the engine to rev up slightly when I slip it into forward gears, but there is no noticeable drag or drop in revs at all when engaging a gear.

What could fail in the tranny or torque converter to cause a failure like this?

I checked the selector lever on the tranny thinking it may have just somehow fallen off, but that is working normally.

Any ideas? How do you go about troubleshooting a drive failure like this?

 

The first thing I'd do is check for leaks.

 

The next thing to check is if it will hold or roll when in park. If it holds in park it is something in the transmission. If it rolls in park then the transfer case has failed.

If it is the transmission there are many different things that could have failed and caused this problem.

 

Most common fail points on an E4OD in my experience is TC and front pump. Mark's experience far outstrips mine, however.

 

I had that happen to me after a gas stop, it happened to be the transfer case. Try putting the truck in 4WD LOW and see if it rolls or tries to engage.

 

This happened on my 1993 2wd F-250. Loud bang, revved up, then nothing. It was my input shaft/torque converter. The splines had been hammered somehow and stripped out. New input shaft, converter, and filter/fluid and everything has been fine since. Probably 8k miles since it happened. $300 and I was back up and running.

I think the T-case can have a pump go bad and catastrophic failure ensues.

 

Gentleman!

Thanks for the insights. I had no idea the transfer case might even be involved.

Will try the in-Park and 4X4 low range checks and let you all know.

It was such a silent and quick loss of drive that it's very puzzling. I'm more experienced at having major noise, shaking or otherwise something very noticeable happen when something in a driveline lets go.

No big leaks either.

I did have the tail shaft frag the tail piece in tranny on this same truck, a few years back, at highway speed moments after passing another vehicle. That made shocking amount of noise, pounding, some smoke, and drained a lot of oil out the area where missing pieces of the case used to be. Waaaay easier to troubleshoot!

 

This truck has been sitting for several years since I first started this thread.

In the interim, I did the in-park, rock the truck test and found it was not the transfer case....it's tranny related. To re-cap, it was a completely silent release while in cruise, on the hwy, with medium load, and it just lost all drive. No slipping first, no shudder or shake, no noise of any kind except the engine suddenly revving up. It was like I had shifted into neutral.

I picked up an OBDI code reader last year and was surprised to find the only code fed back was KOER (Key On Engine Running) 311. The battery had gone dead sitting, of course, before I got to this, but I would have thought that trying to engage the tranny and having nothing happen would have raised more complaints of some type. I tried 3 times, reseting with battery disconnected between each attempt, carefully following the manual, playing with the shift lever lots each time and got feedback indicating plenty of things OK and only this 311 complaint code (Thermactor air system/fault during engine run self-test). Seemingly not too helpful for a tranny issue. (I think this only pertains to engine smog stuff)

Spent some time playing with things then and left if for a good period again. However, needing my truck more often, I'm putting it back on the road whatever it takes. Read through some very good info here again today, and have a question.

What does the Neutral Safety Switch do & is there a way to test it? Is simply an open/close contact switch?

My truck acts like it's in neutral all the time with not a hint of engaging into any gear forward or reverse. The left side connector at the tranny is also a likely suspect if it has lost contact somehow, but most of the complaints I've read involving that indicate bad shifting, certain gears not engaging, or random shifting. I haven't found one yet that matches the complete and very quiet loss of engaging in any gear and acting like it's permanently in neutral.

I'll be under the truck tomorrow trying several of the things I read here today (including cleaning those troublesome connectors at the tranny), but if anyone has insight from a similar issue, I'd be happy to hear about it.

Thanks!

 

The neutral safety switch, or MLPS, prevents starting unless the shift lever is in park or neutral. It has no effect on transmission operation at all. The other connector provides comms between the ECM and various shift solenoids in the valve body. Neither should cause your symptoms. I believe you've lost all fluid pressure, which would basically leave you in neutral. Only thing I can think of that would cause this is a complete pump failure, and that usually gives some warning signs before it goes. I think. Of course torque converter or flexplate, but those usually go with a lot of noise. A simple check for pump failure (I think) it's to check fluid level. Check with engine off first, should show over full. Then check with engine running; if it's still high, the pump is not working and fluid is just sitting in the pan.

 

Thanks Stickman!

Thanks for the feedback, helps tons. That fluid level check is a simple but obviously great test. I'll do that first thing when I get into it tomorrow. Sounds like I'll be dropping the pan at very least. Not sure how the oil pick-up is situated or shaped, but there's some chance something (not good) is clogging & stuck in the pump intake? (if it's not a complete pump failure itself).

I will be diligent and report what I discover, or don't, to maybe help others in the future with a similar issue. This site is a goldmine of information & I don't want to be an abuser taking all the input and not contributing at least something.

 

+1 for checking the pump. The trans in my friend's Chevy failed suddenly like that. He stopped, went to accelerate again, and had no go whatsoever. He did say it had been acting a little funny for a while. We did an autopsy and found that the pump rotor had gone all to pieces. There was metal everywhere.

If you're not sure after doing the dipstick test, you can disconnect the hoses to the tranny cooler and put them in a bucket, then start the engine. That should tell you pretty quick if the pump is working.

The filter wouldn't clog all at once like that. Unless it fell off the pump somehow and left it sucking air, I doubt it's the problem.

 

The Manual Lever Position Sensor (MLPS) used on the E4OD has a large influence on transmission operation. The computer relies on the MLPS feedback for the desired gear and EPC pressure calculations.

Read the MLPS operation theory in this diagram.




A common symptom of a failing MLPS is false neutraling while driving down the road. I doubt it is the root cause of the OP's issue but I wanted to point out your statement is not 100% correct.

 

Even if you unplug all electrical connections on the E4OD, it will still go into reverse and also into drive, although it starts out in 4th gear.

 

rla2005, thanks for that correction. Adding this to the list of things I've learned from this forum, and saving the diagram. I thought the MLPS was a simple Neutral Safety/Backup Light switch.