1983 MB300CD Transmission shifting problems
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1983 Mercedes Benz 300CD
1983 MB300CD Transmission shifting problems
I just purchased the car with 157k miles. It has been relatively well maintained but, there are some shifting problems. I need some guidance with trouble shooting and resolution. The situation is this:
1. No leaks, rattles, sqeeks, etc. Fluid is clear and doesn't smell overheated.
2. When flooring the engine from a stand still the tranny shifts firmly at the shift points.
3. But, if accellerating at a leisurely rate, the tranny will allow the engine to overrun and slowly shift from second to third in about 3 seconds. The engine will race for the shift period. Shifting into high is soft but the engine doesn't race. Also, if flooring the engine for downshifting...it doesn't downshift.
4. Lastly, when shifting into reverse, the tranny takes about 3 seconds again to engage. But when engaged it is firm and doesn't slip.
Any thoughts ideas or procedures to trouble shoot would be greatly appreciated. Thanks.
1. No leaks, rattles, sqeeks, etc. Fluid is clear and doesn't smell overheated.
2. When flooring the engine from a stand still the tranny shifts firmly at the shift points.
3. But, if accellerating at a leisurely rate, the tranny will allow the engine to overrun and slowly shift from second to third in about 3 seconds. The engine will race for the shift period. Shifting into high is soft but the engine doesn't race. Also, if flooring the engine for downshifting...it doesn't downshift.
4. Lastly, when shifting into reverse, the tranny takes about 3 seconds again to engage. But when engaged it is firm and doesn't slip.
Any thoughts ideas or procedures to trouble shoot would be greatly appreciated. Thanks.
Last edited by bjohnson@rtasys; Jun 9, 2009 at 09:19 PM. Reason: additional info
Super Member
Joined: Aug 2005
Posts: 801
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From: Mercerville New Jersey
1991 560SEC Teal 1989 420SEL Ice Blue 1984 500SEC White
I beleive the reverse situation to be about normal.
The other problems sound like a vacum problem, or possibly a need to have the transmissin modulator replaced or adjusted.
The other problems sound like a vacum problem, or possibly a need to have the transmissin modulator replaced or adjusted.
Thread Starter
Newbie
Joined: Jun 2009
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1983 Mercedes Benz 300CD
1983 MB300CD Transmission shifting problems
Thanks for the reply. I can't find any tech data on the tranny. Is there any procedure or specific tests that I can perform? I perform my own work until it comes to the injector pumps and injectors. I have tools and some test gear along with a portable vacuum system.
Again, thanks for the response.
Again, thanks for the response.
Super Member
Joined: Aug 2005
Posts: 801
Likes: 1
From: Mercerville New Jersey
1991 560SEC Teal 1989 420SEL Ice Blue 1984 500SEC White
On the side of the transmission is the modulator. It has a rubber cover and under that is a T key used to adjust shifts. It should only be adjusted in small increments. Turning clockwise makes the shift softer and counter clockwise hardens the shift.
This is how it is on a w126. Hopefully someone will chime in to confirm movement of the T key.
This is how it is on a w126. Hopefully someone will chime in to confirm movement of the T key.
