I recently bought a E320 4Matic, 1999 with 147K miles on it. Going into the deal I knew that there were issues and these would need to be addressed before the machine could be restored to its former magnificence. Knowing several resources for information/parts and being a DIY enthusiast, I went a head with the deal.
I replaced the front 2 axles, shocks and springs. Several other projects remain, i.e. gear shifting issue, stuck sunroof and horn not working etc.
The next project I am taking on is the gear shifting issue.
This issue has me perplexed and I am hoping that the knowledge base of the collective can be brought to bear to resolve the issue.
Here is the scenario;
The gear shifter has 1~4 for manual shifting then D (Automatic drive and Overdrive AKA 5th gear), Reverse, Neutral and Park.
When the car is driven in manual mode, gears shift smoothly when one up shifts or down shifts 1~4.
Reverse is fine as well.
When one puts the trans in Auto mode the shifting is delayed and erratic. Sometimes it will shift at the correct moment other times it won’t.
Now for the enigma; There is some play in the shift lever and its only in “D” and no where else. If one holds the shift lever while in “D” (mind you no force is needed, just the weight of ones hand holding it back in “D” the shifting is fine! No issues. As soon as one lets go, its sluggish again! As if the trans is not connecting/engaging properly.
As part of my investigation, I took out the floor gear shifter completely and put it thru the motions without connecting the shift cable. The shifter is tight in all positions even “D”! No play what so ever! I changed the shifter bushing and retaining clip just as a precautionary measure since they are so economical to change. I cleaned out (Flushed) the gear shifter with contact cleaner and blew air thru it to dry it out. Cleaned all the connector pins for the wiring harnesses.
(I am sharing nothing new here but thought that I would just add this piece of information) The gear shifter is mechanical only for positions P, R N and D, positions 1~4 are shifted electronically.
I did notice that there was a gooey coffee like stain on some sections which was all cleaned and air flushed. I doubt that this would have affected the mechanical shifting mechanism as all the lever does is change the position of the gear shifting linkage which is attached to the trans. I am assuming that the position of the lever is highlighted by the led strip in the shifter unit (for night driving etc) and this is the extent of the purpose for the electronics as they relate to the motions off P, R, N and D!
I reattached the shifter to the trans and bolted it back and the issue returns!
I intend on doing the following 2 items today and should these have any impact on the issue, I will post the results, other wise please assume that the issue persists.
1. I am going to take out the shifter completely and drive the car by shifting by hand the linkage. This should shed light on whether the gear shifter is the culprit or the linkage cable as it positions itself relative to what the trans needs.
2. I am doing a trans fluid change today just for an added measure (also several threads here advised it) but doubt that this will have any impact as the fluid level is fine.
3. I am going to change the shifter unit next weekend unless someone has any other suggestions. ( I found a junk yard nearby that has one relatively inexpensive when compared to the price of a new one)
I would go in to the dealer but fear that all I am going to get is advice that the trans is the problem when any one reading this with any mechanical inkling can deduce that its not.
Thank you, for taking the time to read this post. Any insights that you can share would be greatly appreciated.

Our 1999 E320 4-Matic sedan was having erratic shifting problems, although none like you've described, and the problem was that transmission fluid had leaked past a cable seal in the pan and wicked up the wiring harness to the transmission control module. This is a known problem with these cars.

As I am sure you are aware, these transmissions are electronically controlled and are equipped with many sensors that report back to the transmission controller, and through it to the main engine control unit. I would recommend checking the system for trouble codes before going any further; you should be able to find an independent mechanic willing to do this for very little cost.

I am strictly speculating here, but it could be possible that the transmission controller goes into a different processing mode under which it ignores certain signals coming in through a polluted/shorting harness when you shift up through the gears manually than when you leave it in fully automatic mode. This wouldn't explain why it behaves differently when you hold the shifter against the stopper, but anything is possible.

Best Regards,
Rob

__________________
Robert Fini

'12 ML350 BlueTec, 100k
'06 E320CDI (x2)
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 70k
'97 C36AMG, 319k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)

Thank you for the support friend! I drained the trans along with the torque converter and changed the ATF fluid. Shifting improved. Gear shifter still needed to held in position...but car drives fantatsic!
I adjusted the gear shift linkage setting. The shifter now stays in drive but now I must hold the gear shifter to keep the car in reverse! Sometime one just cant win!!!!
Next I am changing the gear shifter just because that is the next logical progression. Will post the results. Thanks to all for the support.