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Thread: 1993 300E transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

  1. #1
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    1993 300E transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    This is on my '93 300e. I have searched as many threads here and the other ususal MB sites, but have not found any consistent answers as to why this is happening.

    The transmission was operating normally, but suddenly quit shifting from 2nd until around 4,200 rpm. When the transmission is cold it will sometimes shift in the 3-3,500 rpm range, but once hot it's always over 4K. When it does shift, it tends to go to 3rd and then immediately to 4th. The car drives fine until I stop at a stop sign or light, then we go through the whole high rpm shift routine again.

    Initially when I tried to manually shift from gear to gear it wouldn't respond, but now after a fluid change I can shift down and up between 3-4.

    As noted I changed the fluid and filter. I've disconnected the kick down switch, and checked the adjustment of the bowden cable. I even disconnected the switch that delays shifting during warm up, but none of these seem to have any effect.

    I found one thread where another owner had similar issues which were resolved by changing out the modulator valve. This doesn't make sense to me as I undertand that impacts the crispness of the shifts, but I didn't think that would effect the timing. I was thinking it would be worth replacing the K1 spring assembly as I understand that controls the 2-3 shift.

    Any other thoughts, or suggestions are greatly appreciated.

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  3. #2
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Fluid level is always the first check. Must be done full hot with engine running, level ground and transmission in "P". Take multiple measurements and wipe stick with clean, lint free rag, even better is to use chamois type rag for this. Absolutely no dirt must enter the transmission otherwise you're entering a world of pain

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    TerryA (4 Weeks Ago)

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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Yep, it's at the full mark when hot in park with the engine running.

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    TerryA (4 Weeks Ago)

  7. #4

    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    More information. How many miles on the car? Has the tranny fluid been changed regularly? What fluid did you use when you changed it?

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    TerryA (4 Weeks Ago)

  9. #5
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    255K on the car. The transmission is newer, however, of somewhat unknown background. I bought it off Craigslist from a Russian guy near Seattle. Had probably 20 MB's in various states of repair around his property. The transmission supposedly came from a wrecked low mileage car, but no solid details beyond that.

    I put in a new elring filter and Mercon III compatible fluid (I don't remember the brand) when I installed the transmission in the car. It's worked fine for the past 20K or so miles. The fluid both times it's been changed has been fine. No burned smell, and the pan has been as clean as I've seen, so nothing obviously wrong there. This last change I again used an elring filter. I used whatever was on sale at Walmart for the fluid as I expected to change it again if there was improvement.

    The weird thing is it's like a switch was flipped. It worked normally, and then it didn't.
    Last edited by roadster27; 4 Weeks Ago at 10:18 AM.

  10. #6
    Senior Member Eno's Avatar
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Check the bowden cable all the way up and check the wire connections going to the tranny on the sides and rear.
    Also check the kickdown switch behind the gas pedal.


    Sent from my iPhone using Tapatalk Pro

  11. #7
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    As noted above the kickdown switch has been disconnected, and the bowen cable is slackened. What effect does the solenoid on the tail housing of the transmission have? I haven't checked to see if it is being energized. I did see where the fuel relay can impact things adversely. I swapped out the relay with a known good one, but to no avail.

  12. #8
    postwhore posterchild Klink's Avatar
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Interestingly, your transmission is behaving almost exactly as one does with the kickdown solenoid permanently powered. The kickdown solenoid is that electrically operated valve assembly on the passenger side rear of the tail shaft housing.
    To be more precise, it does not actually screw into the tail shaft housing. It goes past the tail shaft housing and screws into the main transmission housing. So, I am going to suggest something like our dates, cheap and easy. Perhaps the kickdown solenoid valve has stuck open and/or an inner kickdown solenoid O-ring is leaking? I would make sure those items are in good order before I did too much more.
    Putting the fun in dysfunction...

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  14. #9
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    Re: 1993 300E transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Thanks for the suggestion. I wish it had been successful.

    I pulled the solenoid, and swapped it with one from the transmission which was previously in the car. Unfortunately there seems to be no change in how things are functioning. I have tried driving the car both with the solenoid connected and disconnected from the wiring.

  15. #10
    Senior Member Duh_Vinci's Avatar
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    Re: Transmission not wanting to shift from 2nd-3rd gear until 4,000+ rpm

    Quote Originally Posted by Klink View Post
    ...Perhaps the kickdown solenoid valve has stuck open and/or an inner kickdown solenoid O-ring is leaking? I would make sure those items are in good order before I did too much more.
    Klink, what impact would the leaking O-ring will have on the shifting action of 722.3? Reason for asking, mine developed a similar issue (but worse)... Cold - fine through all the gears, warmed up, starts with Flaring up 3-4, then eventually 2-3 as well, basically non derivable now. Again, fine when cold, good for 15min drive, but that's all. Boweden cable adjustment does nothing. There is a new leak at the tail shaft area, possibly that kickdown solenoid is leaking.

    Regards,
    D

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