I have an E40D transmission in my 94 SD and I had to rebuild it at 90K because the torque converter died. The long and short is the E4OD has had many problems and after some research I started to add some mods to the trany to keep it alive.

1) Rebuild with all the latest upgrades - and a heavey duty torque conveter - at 90K

2) External trany fluid filter - filters down to 20 micons - 5x better than the internal screen.

3) Extended pan - adds four quarts of fluid to
the tranny

4) New - bypass trany cooler - alows the fluid to bypass the cooler when below 180. Lots of people don't now that too cold a fluid can hurt the trany just as much as too hot.

5) Trany presure gauge - now I can tell when the filter is getting clogged - runs about 26 psi - and can change the external filter in about five minutes . Saved my *** on the long tows several times.

6) Temp gauge - got one in the cap and I always carry a Raytek with me to check the radiator and other temps when I do a fuel up. Got the latest one on Ebay for $60 an MT-6 goes up to 1000 so I can use it on the exhaust minifold to be sure I am not leaning out etc (Gas) - diesel lets me know if I have a clogged injector - many of those while I was runing down the problem with the AZ emissions test.

1990 29' Motorhome on Ford Superduty, 7.5l gas, E4OD rebuilt 10Kmi and two years ago (AAMCO) using "RV" HD converter, also replaced the failed overdrive section .

Since rebuild, when cresting a hill (OD off) get a few seconds good engine braking going downhill, then much less and engine RPM drops off, same in 2nd (Didn't try 1st or OD). If I feather in a bit of throttle, engine braking returns and RPM comes back up. On the flat and uphill all gears and OD seem normal, shifting is smooth.
Seems as if tranni is either not being told (or is not sensing) the engine braking situation, or is not responding to that information. I wonder if the pump is swiching to low pressure (as in coasting mode rather than engine braking mode. Could this be a loose connection in the connector?

I didn't recognize what was happening to Dad's coach until yesterday when I drove another with similar drive train and realized what it was that was missing.

What are your ideas for further trouble shooting, what should I check and how? I have no indication on the dash.

You mentioned a pressure guage, how to install? Will it show the change from ideling (low pressure mode) to driving pressure? As you can see from above, I'm a bit worried that in downhill engine braking, the pump pressure is not being maintained high and thus the clutches are not fully applied. BUT I don't know. All I know about the E4OD is what the rebuilder told me as he was rebuilding this one after the OD froze up (no cause was found, it couldn't even be pressed apart, it had been previously rebuilt 13000 miles earlier by the only shop that would take us in Tulsa (we were on a tight sched cross country) and they found a loose snapring in the OD section). I do have a tranni temp guage (on the pan)and have not noticed high temps going down hill.

Larry

In downhill braking, does the converter unlock? This is kind of what it feels like.

Larry

Should it?

You might need an exhaust brake for an RV or a heavy truck. Getting a temp gauge on an E4OD so
that it provides a good temp is a problem. I just
put mine in the external filter along with the preasure gauge.

Sold Smoggy last month - was planning on getting a new crew cab but the Ford 6.0 is having more
problems with the transmission than I want to deal with. I thought the E4OD was bad - but of over
a dozen people I have talked with the new 6.0 I hear - the truck is great but I have put three
tranmissions in it... Looking at the GM dura-max and the alision six speed as my new candidate.

While checking through the records I realized that I had rebuilt the tranny at 69K not 90 - so in the
end the tranny had lasted 180K without a rebuild or any major maintenance and was till pulling when I sold her. One major plus was the Hughes extended trany pan - with the magnetic drain plug - since it
was so easy to change the fluid and filter I got in the habit of changing it twice a year - everything
cooks here in the summer - I have gound temps at 130+ without starting the engine so I figured I'd just
change the fluid after the summer so I got in the habit of changing out in Oct and again in April before the real heat hits here.

I only changed the internal filter twice in 180K but changed the external filter twice a year. Once
I had the external filter ( put magnetic collar on it also) I really had no need to change the internal filter - when I cut them open there was nothing in them. And there was no pickup on the magnetic drain or the internal magnet - before the external filter they would be covered with metal.