I’ve got a ‘95 E series 7.3 powerstroke with the E4OD automatic transmission. It’s a short shuttle bus body with a camper conversion, weighing around 11,000lbs. On cold starts, the torque converter seems to stay locked in reverse, causing the motor to stall. It’s worse in colder weather, and goes away completely when the transmission warms up. The only time I see any issues when the trans is warmed up is pulling up steeper hills in 3rd gear, even with the accelerator pedal on the floor, it won’t unlock or downshift and can’t get over 35mph. On flat ground and mellow hills it shifts smoothly and will do 80 on the freeway.
I’ve read low ATF can cause stalling in reverse, so I’ve eliminated that.
I don’t have the right pressure gauge to test transmission fluid pressure, but if that’s a test I need to do, I’ll get the gauge.
I added a quart of Lucas transmission slip/leak fix, and the problem went away for a few thousand miles, but now it’s back.
Unfortunately I don’t know how many miles are on the trans, but on the last two fluid change there were a couple little chunks of debris in the pan.


Does anybody have experience with these symptoms? Am I definitely in for a reman transmission, or could I get away with replacing the torque converter? Funds are tight right now, and a torque converter is ~$300. Reman transmission is probably 2k plus. So if I could get another 50k miles or more out of the transmission with a new torque converter, I’d be game for doing the work.

 

Paging @Mark Kovalsky.
Mark is our resident auto trans guru/ ford trans engineer

 

@Mark Kovalsky
Trying it again as I don’t think the tag worked the first time Tom.

 

Are there any codes stored in the PCM? If so, that is where you need to start. If not, reading the pressure when this happens is the next step.

 

Thanks Mark! No codes last time I checked, but I’ll scan again and then get a gauge and test pressure. Does low pressure mean a rebuild, or could there be a simpler fix?

 

Low pressure means a rebuild. A new torque converter won't make any difference.

What fluid are you using?

 

I’m using valvoline max life full synthetic.

 

Is that the one that says it is for MERCON V and MERCON LV? If so, it may be too thin (low viscosity) for your transmission.

 

It says it’s for Dexron VI, Mercon LV, Dex/Merc. Could you recommend a good heavier fluid if that’s too light?

 

If you want synthetic, I recommend Mobil 1 Synthetic ATF. Otherwise, any fluid that says MERCON V on the label. Not a fluid that says for use where MERCON V is recommended, but displays MERCON V right on the front.

DEXRON VI and MERCON LV are way too thin for your transmission. On top of excessive wear, the thin fluid will cause the torque converter to lock when it shouldn't be locked. Get that crap out of your trans!

 

Thanks so much! I’ll get that fluid changed asap and see how it acts from there! I’m thinking back to the first fluid change I did after getting the rig, and I think I just used whatever the parts store said would work. That was before I learned not to listen to them without at least searching the forms first. Been running that stuff about 80k miles 🙈
I really appreciate you checking the basics with me! Hopefully the right fluid will at least buy me some more time to save up for a rebuild.