I'm retyping this due to a misclick so my thoughts may be a bit more jumbled this time that the last
The transmission fluid flows out of the coolant line at the front of the transmission and in at the back of the transmission. The coolant route should go out the front to the in radiator transmission cooler then to the oil to air cooler in front of the a/c condenser then to the hard line going to the back of the transmission. Be aware that not all of the oil is cooled on every circulation plenty returns to the pan by simply dripping from the valve body.
The stock transmission cooling systems on these trucks is far from adequate even for a truck that is running around empty. If you do not already have a larger transmission cooler then that is a good place to start many of us have used the
tru-cool 4590 with good results, however you can get a big more cooling by using the
Tru-cool MAX if you get the max make sure you get the bypass valve version so the transmission has the opportunity to warm up in the cold winter months (the 4590 has it integrated). When installing either of these simply replace the factory oil to air cooler with this one. As far as a restriction yes it is possible there is a check valve at the return that could not be opening entirely but that would be due to trash in the system most likely.
The E4OD transmission has known problems in a handful of areas especially when it comes to use of exhaust brakes (don't know why this didn't hit me before now
) Anyway, this makes for time to play 20 questions with your transmission shop. What did they do to your valve body, did they rebuild it? if so what did they rebuild it with? Did they perform any upgrades to the valve body? I would expect baffled looks and tap dancing around the issue or "we built it to ford specs" in which case you need to upgrade it. The rather popular valve body rebuild kit/reprogramming kit/shift kit that has proven itself many times over is the
tansgo tugger HD2 this kit as you can read in the description is designed to help the holding pressures and fix some of the common complaints about the E4OD and by doing so help it to run cooler and last longer. If you get the kit you do not have to do the upgrade pieces to the front pump unless you are dying to pull the transmission or pay for that to be done, it'll do what you need without those upgrades just save them in case the transmission needs to come out at a later date.
Back to quizing the transmission shop. Did they replace the torque converter? if so what did they replace it with? Any alteration to the stall speed? Stock converters have a semi-high stall speed which is ok for the factory power if you get a chip then a lower stall will help keep the trans temps down a bit but is not required. but be aware that stock spec converters tend to be rather weak and would be the most likely point to fail first. Also is it the 94-97 stock stall speed or the SD stall speed, the SD has a higher stall speed than the OBS truck and will create more heat than the stock converter. If they didn't replace it this would be a good idea to replace & upgrade, good converters are 800+
Ok the converter lockup when driving slow. Since your in CO, playing on FS roads I'm guessing/hoping that you have 4WD, in which case your answer is easy, just drop the transfer case in 4lo (you don't have to lock the hubs) this will allow the transmission to spin fast enough to lock the converter but the truck is going slow enough for the roads.
PCM code & Chips... most likely your pcm code from the factory locks the converter and keeps it locked until you engage the service brake or hit the brake pedal enough to trigger the brake lights then it remains unlocked until you are on the gas pedal again. For the chip if you have a banks chip then I'd throw it on Ebay with a good description and it will help to offset your cost of a good chip. Banks does not change any transmission parameters on their chips but relies on their transcommand module to do that (which is not needed with the valve body). Tony wildman at total diesel performance or DP-tuner will be able to take care of you and get you what you need just tell them what you are doing and you'll get what you need. My preference for the OBS is Tony and I like the rotary knob to switch better than a digital push button display. In addition to a chip it might be beneficial for you to have a torque converter indicator light wired up and/or a manual torque converter lockup switch. (if you like the idea then I'll explain further)
Speaking of torque converter lockup in the back of my head I'm wondering if the torque converter is even locking up. Easy test to see if it is locking up: Drive down the road (flater section) at 45mph or so then rapidly accellerate but do not hit wide open throttle. pay attention to the RPM do they rise gradually with the speed or do they spike up immediately? You should not feel a transmission downshift when you hit the throttle.
