No forward in transmission. 1984 300d w123
 

Ok I was driving along this morning and my transmission just dropped out of gear with a bit of a bang. Never would go back into gear. Reverse still worked and I made it the ~1-1.5 miles back home.

It dropped out twice in the past month or so for about a second before kicking back into gear. At that time I checked the fluid level and it seemed fine.

It has always been a bit rough in shifting (ive had it for about a year and a half.) but I always thought it was vacuum issues.

Is this likely to be the b2 piston?

Yes, my dads 300sd did the exact thing your car did. Lost foward gears but still had reverse. Changed b2 piston and it was back to normal.

Dammit. Went to change it and the piston was fine. The part in the transmission the push rod goes against on the other hand was not. Looks like i need a new transmission or a new car. not sure which.

Thoughts on going manual?

Some people think the conversion to manual is the best solution to a broken automatic transmission. I think replacing with an other automatic transmission is less work than a conversion for the average DIYer. I think a certain dedication and a love of manual transmissions is required to do the conversion. It is a lot of work.

Found a 1977 240D with an automatic. Would it be a possible donor for my 84 or is it too old?

Not a good choice. Weaker unit and different control system I believe.

722.433 INFO
 

hey,

had the same problem a while back, with my w124/722.433 transmission.


before pulling/replacing the transmission, try dropping the valve body and then inspecting the B2 brake band.


the problem could be that your b2 brake band needs to be adjusted via new(longer) thrust pin. its an inexpensive repair, a new longer thrust pin + retainer clip = $15-20 from dealer.

or

worse case scenario: broken b2 band = would require a rebuild


drop the valve body and take a better look.

good luck

It is the band itself. Metal is completely sheared. Im not gonna bother with a rebuild. No need to remove the valve body to see

Well after letting this sit for a bit longer than i meant to I may have found an 84 190D with an auto transmission for cheap. Is this a possible option for a donor?

The 190 has a different series of motor ,which part of the US ?You can find some part cars under CL sometimes with close locations .

I found this 190d on craigslist. And it is the transmission I care about not the motor.

Usually coming from a different series of motor will mean it will not bolt up to your engine...

I did the switch from auto to manual, and well worth every minute. Actually, about a one day operation collectively.

That trans from the 190 definite won't bolt up. Starter motor's on the wrong side.

Keep looking.

http://robertspartsupick.com/inventory.aspx?make=MERCEDES-BENZ&model=380 Would this be a donor car?