Ok i have just completed the pressure tests and the results are as follows

Line pressure: in spec. both at idle in D and at converter stall in D.
Governer pressure: NOT IN SPEC. instead of being between 1/2 and 3/4 of the road speed it is functionally 1:1 with speed. so at 30 mph it also indicates 30psi.

According to both repair manuals it states "If the pressure values differ the fly-weight governer needs to be replaced". So it appears that I will need to track down a NOS or good used governer.

The highlighted statement indicates HIGH governor pressure.
High governor pressure is associated with EARLY shifts, not delayed shifts!

That's interesting. If true, I have no idea what is happening then. I have the Bowden cable disconnected, and it makes no difference. If the governor's pressure is high and should cause early shifts, then this transmission has lost its mind and is doing the exact opposite of what it is being told.

Are you sure its not the other way around?

I just realized that I had had the Bowden cable off as it appears to make no difference. However, it may still make a difference to the governor's pressure, and having it off during the test may have given erroneous readings. It's late, so I'll test this tomorrow and report back.

nice work

Understand what you're saying but it may be just stuck because it's dirty.

Good luck and keep us posted.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Very true; I will inspect it closely when I get it out. I will probably source a new governor regardless, as I don't want to keep this car off the road for long and would rather have a new one on hand if it turns out to be worn. I figure I can return the new one if the old one was just dirty.

Thank you to everyone who helped and pointed me in the right direction. I'll report back with the results when I have it all done.

Control pressure and governor pressure are the yin and yang of shift timing; more control pressure > later shifts; more governor pressure > earlier shifts.
Control pressure, via the throttle linkage and control pressure cable, is balanced against governor pressure. More throttle during acceleration causes more control pressure, and delays the shift point. Drive off with light throttle, and less control pressure, and the shift comes earlier.

Thank you, I just did some quick reading to understand shift valves better and got a better grasp of this. Still very unsure of what is going on, but I gather that either the control pressure is staying too high or the governor pressure is too low and easily overcome. We know that the governor's pressure is not too low. It is, infact too high, so the only thing left logically is that control pressure is way too high and overcoming the governor. The Bowden cable moves freely and returns to its starting position normally, but the control pressure valve may be stuck at WOT internally. What do you think if you had to guess?

Alright, I tested whether attaching the Bowden cable made any difference to governor pressure, and it did not.

Success! Just to update this thread, I made a last-ditch effort before opening the transmission pan and added some Trans-X additive as recommended by **************. And wouldn't you know it, after about 20 minutes of driving, it suddenly started to shift on its own. Over the next 10 minutes, it improved until it now shifts about as good as I could hope for with transmission of this age. I realize that this is unlikely to be a permanent fix, and I will need to go through and clean the valve body, but I am VERY happy that I can now drive normally.

Great news!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Good news indeed but what this tells you beyond any doubt is : it DESPERATELY needs a filter and ATF change including the torque converter .

I too am a believer in TRANS-X .

I used the yellow bottle, there was a bewildering array of choices in this one brand .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Yea, I agree 100%. I am going to flush the entire system, including the torque converter. I Already have a new filter, gasket from Mercedes, and some Dex/Merc fluid. I also used the yellow "high mileage" bottle. This is the first time an additive has actually "fixed" a problem for me.

Good .

How will you flush it ? .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better