Hello all, I have a 1985300 SD. I drove the car on a 120 mile trip today and returned home. I just got in the car to go to the store and the transmission will not shift. I have checked the fluid level and it is fine. The transmission has been working fine. Does anyone have any suggestions or thoughts on what happened and what my next step should be? Has this happened to any other members? Help Please.

Thanks
Jack

Do you have reverse?

Check the plastic levers on the top of the valve cover. I think the SD has 2 of them. They activate the 3/2 valve. They are tiny, but caused me alot of troubleshooting time. Also, obviously, check all vacuum lines in the engine bay.

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1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

I do have reverse. I drove it in reverse part of the way around the block to see if that made a difference.

Well, you're in luck.

The symptom is classic for a cracked B2 piston. Do a thorough search on here for the best technique to replace that piston while the tranny is in the vehicle. It's a bit meticulous but not costly.

You'll need to order some OE parts.

How do I verify that it is the B 2 piston?

post #5


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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

At this point, verification can only be realized if you go in and remove the B2 piston, at which point you will be able to observe if it has failed.

This is your only option at the present time, other than removing the entire transmission, which would be foolish.

Do you have any forward gears?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

You mentioned that it wont shift. So, does it just stick in first gear when moving forward? If so, may not be the B2.

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1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

Just got home from church. I am going to check vacuum to the modulator valve. Last night I tried it again. I started off in low gear and the transmission would not shift until I got to around 6000 rpms.

Then the problem is not the B2 piston. You need to unplug the kickdown switch and check that the bowden cable is moving freely.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Agreed.

A complete failure by the OP to provide the precise symptoms of this problem leads to another wrong conclusion.

.

I believe that in case of kick down and cable he could not upshift from gear
to gear... but start and simple go would be ok...I guess

...but you never know,until you try


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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

Well Praise The Lord. My kick down switch was stuck. I was getting ready to check the vacuum and the bowdan cable, and got the post about switch and found problem. Thanks soo much for all that shared their knowledge. I love this Forum. Thanks again.

Jack