Im looking at buying a 91 f250 4x4 with a 5.0 and an e4od. When I start the truck I can feel It roll forward A little bit. I can put the trans In od or nuetral and It will drive and shift normally thru all 4 gears, no slipping and no noise no vibration, It shifts and acts perfectly normal. 1st and 2nd work fine as well. When I put it in reverse It rolls forward slightly then drops Into reverse, it will not actually back up, you can rev the engine to stall speed but no higher. Sometimes in park If you rev the engine It will actually over come the parking pawl and roll forward. Also when In park I can rev the engine to stall speed only. It only starts in p or n, and the reverse lights come on in R so Im assuming the mlps is adjusted properly and the manual protion is adjusted properly. I pulled codes and had 3 in total, ect shorted, egr flow insufficient, and 1 code for torque convertor clutch solenoid I believe It was 632. Im assuming the reving up to stall speed Is related to the tc code. The fluid level Is fine but is a little dark In color, I tried doing a search with no luck If there Is a post for this please direct me there. thanks

 

I think the forward clutch has failed and welded itself together. Locking the torque converter can't do this.

 

Thanks for the reply, I was kinda hoping It would be a solenoid problem but you and multiple other people have said the same thing that the forward clutch Is damaged. again thanks for the reply

 

There is nothing electrical that could cause this. It has to be a mechanical problem.

 

My 96 F350 7.3 Power Stroke 4x4 E4OD also remains forward in all gears. It drives and transitions normally through all gears. All gears work therefore the TCM/PCM (Transmission/Powertrain control module) works, but the transmission is always engaged in drive which also causes loaded starts.

I flushed the torque converter/main case trans oil, changed filter, MLPS (manual lever position sensor) or also called a NSS (neutral safety switch) and solenoid pack. No drive when the solenoid pack was disconnected, but all shift positions produced forward drive when connected.

Since the reverse (with lights) and neutral positions alone allow start, the NSS works. However, since drive works in all gears the torque converter is good, but since it will not release drive my next best guess is the clutch assembly for not physically disengaging drive

Let me know what you've found. looks like I'm going in.

 

It should NOT start in reverse! Only park and neutral, but I digress. That has nothing to do with going forward in all positions.

That problem is caused by a failed forward clutch. It's welded itself together so that it cannot release, which is required for park, reverse, and neutral.