Hey guys,

I recently acquired a 1984 300D (auto transmission) that will not shift into gear. Shifting between park and neutral is no problem which makes me think it isn't a gear selector issue but I could be wrong. Could this be a vacuum issue? I know the car does have a vacuum leak because it shuts off very slowly. I have looked around online a good bit for answers but it seems like everybody's issue is a little different! I'm not really sure where to start troubleshooting this problem so I'm hoping you guys can point me in the right direction.

Thanks!

Are you saying that the shifter will not move or that the tranny will not shift when you try to drive? Need a bit more information. Does it drive at all?

If it is slow to shut down, you may have a shutoff valve problem. Shutoff valve is in the rear of the injection pump and has a nipple with a vac line. You can pull off the vac line, attach a Mityvac, and see if it will hold a vacuum; if it does not, it is bad and must be replaced. Then again it could just be a leak in that vac line or rubber connector (easiest fix). Also make sure that your shutoff lever is all the way up; if it is partially down, it would affect your shutdown.

This pic shows the location of the shutoff valve in my 300SD; assume yours would be in the same place.

The shifter moves fine but the car will not go into drive nor reverse. The car does not drive at all because I can only go into park and neutral.

1) Ensure that the entire driveline is intact: transmission, shift linkage, flex discs, drive shaft, differential, half-shafts.
2) Ensure that there is fluid in the trans, and at the correct level.

If 1 & 2 are satisfied, there may be a failed front pump in the trans, or a valve body fault.

Note: Unless the transmission has been changed to something non-MB, it has four forward speeds, no overdrive.

Odd; I do not see the pic that I attached.

Take a look at the bushing under the shifter that is a pivot point to the trans. Make sure it's in good shape..Cheap fix.