1966 230SL Transmission

[Harry]

These grand old cars - can be a bit temperamental.  I took a short ride in mine this afternoon and the transmission began acting up before I got home.  Up to this point, the tranny has been marvelous with no issues.  Now, shifting from a stopped position (2nd gear) is greatly delayed, requiring a high RPM before it would shift into 3rd.  And even so, it seemed that I had to "play with" the accelerator to get the tranny to shift.  Once it did, the shifts into 3rd and 4th seemed mushy, i.e. not the normal crisp shift.  Downshifting didn't seem to be an issue (although it might possible that even that was a bit mushy).  I did check the fluid level (hot, idling and in Park) once home and it appeared to be fine, if not a wee bit full.
So as usual, I am relying on the experts here to provide your advice on what to check.  I have been reading the Tech Manual and will continue along that course but I thought some early counselling might be particularly helpful.

Sincerely,
Harry

[MartinK]

Hi, in most cases the error is located in the peripherals. First I would check the doubl stroke selenoid (?) and the idle switch on the throttle valve for functionality. In the best case, check the modulation pressure, too. Seems a bit, that the operating oil pressure is too low. Maybe the solenoid on the top of the trans is stuck in idle position.  Good luck. Talk soon, Martin.

[Harry]

I removed and cleaned the throttle switch today and doing so seems to have helped.  During the short test drive, with several starts and stops, the tranny was shifting normally from 2nd to third.  But the shift from third to forth seemed a little soft to me, as opposed to the more typical instant change.

I'll do more diagnostics tomorrow in accordance with the Tech Manual.

Harry

[rwmastel]

First I would check the doubl stroke selenoid (?)

Martin,
What is this?  I'm not familiar with the name.  Maybe the name is lost/changed in translation.

[ja17]

Remove the access cover on the side of the transmission tunnel inside the car. You will be able to view the linkage between the three position solenoid and the modulator valve. Most likely the pivots for the linkage have become corroded and stiff. Spray with penetrant and lubricant and exersize the linkage rod so it moves back and forth freely.

[MartinK]

Hei, I mean the three positions magnet / selenoid. The actuator for idle/drive/ kickdown located on the top of the Transmission. Sometimes it is seized or the linkage is worn out that the transmission gets a wrong operating pressure. Sorry for bad description. Martin

[WRe]

Hi,
three position solenoid explained: https://youtu.be/0egCYWAcyao?feature=shared
Sorry in German but you can use English subtitles.
...WRe

[MartinK]

Hei, WrE. Interesting how pictures multiply, this is a picture from my stock. Do not forget to fill the ball joint with grease and add gasket A0009976041 before connecting. This prevents the moving part against moisture. As you can see on the picture, the seal is missing and the ball joint is dirty.  See here: https://mercedesclubs.de/onlinekatalog/6035-0009976041

[Harry]

I think a contributor is that my throttle linkage is a bit sticky and not allowing the throttle switch to fully close or to do so intermittently.  I’m going to clean and lubricate all of the ball fittings.  What is the optimum lubricant?  I suspect something more lightweight?

Thanks,
Harry

[Pawel66]

I am not a mechanic, I just had my deal of my car tuning.

One point from experts I took very seriously in the very beginning of my journey: the car has to be in tune to shift as she should.

The car is not in tune if the linkage is sticking.

Shifting depends on ignition timing, valve clearances, idle adjustment, quality of brake booster work, throttle switch work, probably some other factors too (transmission is controlled by vacuum and electric signals). Then it has a chance to shift smoothly. There may be other factors that will prevent smooth shifting, but the above is entry condition. That is what the experts said to me.

[rwmastel]

Harry,  A drop of ATF in each socket would do.