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W123 300D (1981) & W126 380SE (1985)
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34 Posts
Discussion Starter #1
Hello out there! After a period of "slapping" (flaring??) the auto in my 1985 380SE has decided against any further forward action. There is plenty of clean fluid, and reverse seems fine. She just makes a huge fuss about going forward in Drive (lots of revs and a bit jolty). Can anybody please shed some light on what might be the problem here. I understand that all W126 autos are similar. As I don't have a book on the transmission it's a bit of a mystery. I understand these are strong boxes and the car has reasonable mileage @ 135000 (220000kms). I would prefer to repair an isolated problem or two than make a huge drama and change the whole thing over. In addition, this car only had three forward gears rather than four as stated in the owners manual. Is it possible that a failure to engage in fourth is connected to this current problem? Look forward to hearing from anyone with some technical advice. Cheers, Ed
 

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CH4S Admin , Outstanding Contributor
1985 500SEC, 1991 190E 2.6.
Joined
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40,112 Posts
Many of our cars have a feature that makes them idle and start in second gear, which might make you think there are only 3. The first gear you get with the kick down from a standing start.

Have you tried a forum search? The archive has a wealth of information.

Please click 'User CP' on the top tool bar, and complete your profile with a location and model of your car.
It makes it easier for members to offer advice. MB produced different, and region / Country specific versions of our cars.

Welcome, to take advantage of all the forum features, please re visit the 'Welcome to the Forum' tutorial sticky on top of the W126 page, as well as the two DIY stickies.
It will show how to search the forum (3 words min.), and has a link to the Russian MB site where you can run a VIN#.
Cheers
 

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Registered
1990 350 SDL
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2 Posts
I have a 1990 350 SDL and just recently I have been experiancing wierd tranny issues....On the highway crusing at 110 km/h the car felt like it jolted and paused and all of a sudden the rpms shoot up, and car is revving high, almost seems like it was no longer on 4th. Then at low speeds it wont change gears right away. I had the vacuum system fixed by mercedes recently, if I get good speed and maintain it with cruise control, i dont have any problems, but if I have to use the gas/brake pedals, nothing but jolts, high revs, feelings of downshifting...is it my tranny?, Mercedes said I would needa new torque converter and tranny, but I'm not sure, the car is good and ran great up until now. I do not think they adjusted the vacuum system, all they did was repair it any ideas Im desperate I do not want to drop 5Grand on a new tranny. Thanks
 

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Registered
W123 300D (1981) & W126 380SE (1985)
Joined
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34 Posts
Discussion Starter #4
So far my investigations have lead to possible problems with the auto transmission modulator and/or the B2 piston in the tranny. I am hoping this is correct since neither of these causes requires tranny removal and can be done in-car. I will try to do the job myself when I have time. I guess it will be a question of testing the modulator which is apparantly vacuum controlled, removing the B2 piston and checking condition, etc; obtaining the exact transmission number (located alongside the tranny sump pan) and then obtaining any necessary parts and re-installing. My impression of tranny mechanics is that they will not repair anything-only replace whole boxes. This may be unnecessary on many well made vehicles.
 

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CH4S Admin , Outstanding Contributor
1985 500SEC, 1991 190E 2.6.
Joined
·
40,112 Posts
I have a 1990 350 SDL and just recently I have been experiancing wierd tranny issues....On the highway crusing at 110 km/h the car felt like it jolted and paused and all of a sudden the rpms shoot up, and car is revving high, almost seems like it was no longer on 4th. Then at low speeds it wont change gears right away. I had the vacuum system fixed by mercedes recently, if I get good speed and maintain it with cruise control, i dont have any problems, but if I have to use the gas/brake pedals, nothing but jolts, high revs, feelings of downshifting...is it my tranny?, Mercedes said I would needa new torque converter and tranny, but I'm not sure, the car is good and ran great up until now. I do not think they adjusted the vacuum system, all they did was repair it any ideas Im desperate I do not want to drop 5Grand on a new tranny. Thanks
Welcome, see the post above yours re search.
Cheers
 
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