1984 300DT: car will not start in park.
 

90% of the time, the car will only start in neutral. What could be wrong?

My bookie is giving 5:1 odds that the problem is the neutral safety switch or its adjustment. Shifter linkage adjustment is another possibility.

It could be he shifter bushings are worn or gone. There is also shifter bushings under the shifter lever.

You can crank the starter by way of the terminal block on the fender in front of the Battery.
When you sit in the Drivers Seat to the right of your right knee under that panel where you can bypass the neutral safety switch (remember to keep it out of any gear when you crank because it will start in any gear if you bypass).

http://www.peachparts.com/shopforum/diesel-discussion/333784-neutral-safety-switch-troubleshooting-84-300d.html

shout out to those who posted replies; I'm going to look into both the NSS and the shifter bushings and will post back here when I have more information. :D

If it starts in "N" but not "P", the problem is usually a loose shifter linkage. Usually it is due to the plastic bushings on the underneath rods cracked and fell out. The bushings are cheap, but replacing them is tough since little room to work under there. I bought the special $17 pliers tool which helped, but was still a fussy job. Watch the Mercedes Source youtube.

I have replaced bushings. No special tools and a very nice result. Do it anyway on an old car, it is only a matter of time before failure.

thank you for all the replies; I'm calling this week "transmission repair week" because I'm getting into transmission issues. I have a list:

1. Replace and adjust the Bowden Cable.
2 Replace bushings in shift linkage.
3. replace and adjust modulator valve with new green modulator valve.
4. change transmission fluid.
5. locate and repair vacuum line leak, doors do not lock and unlock properly which I believe is affecting the transmission.
6. try and locate and purchase magnets for transmission pan (I dunno if these are worth purchasing but it looks like a good idea......)

Routine Service
 

Do remember to replace the tranny oil filter, not just change the fluid .

The torque converter has a tiny 5MM plug that's tricky to get lined up then it's easy to remove and drains the torque converter, this is very important as much crud and old worn out fluid remains in the T.C. unless you remove this drain plug .

Magnets are a good idea, Harbor Freight sells little tubes of rare earth magnets cheaply one or two in the pan will suffice .

The price has dropped yet again ! : https://www.harborfreight.com/search?q=rare%20earth%20magnets

The shifter bushings are fiddly but very important, do change them .

For now, cap off the yellow plastic pipes, that's the vacuum circuit for the door locks .

? Where did you find the tranny modulator ? . I spent spme time looking to no avail .

Don't forget you'll need a gauge to test & adjust it, again not really hard but dirty and fiddly .

concerning the modulator, I purchase from quite a few different supply houses so I can't say for sure where I got mine from. That said, I noticed it is for sale on this web site.

And, a news flash as if some of you were not aware. More and more parts for our vintage Mercedes Benz automobiles are going NLA. So......if you are serious about keeping your vintage MB car in good operating condition, I would suggest stocking up on key parts while supplies last.

Yeah no kidding.

I think there is some hope with URO continuing to supply some of the parts. We also have Turkey making things for these cars.

We need yards like Rollguy’s in Hesperia if we are really dead set on keeping on keeping on. I’m not sure I have that level of dedication.

I understand. that said, Jay Leno has managed to keep his vintage Duesenberg automobiles running by making his own parts in house. Think about this, we've sent men to the moon with the Apollo space program. If we can screw together a rocket and a man carrying capsule which landed men on the moon, we can certainly figure out how to make a few NLA mercedes parts, don't you think?

Reporduction Parts
 

Yes, it can be done but the cost is prohibitive .

Where there is a will, there is a way. Right now today, MB is forcing all of us vintage owners to make a decision. The decision is whether to keep our cars on the road OR not. We use either gently used parts or attempt to manufacture our own. I'm also aware that the COVID crisis forced some MB parts suppliers out of business.

We definitely try to find stuff going NLA. If the numbers pencil out (tooling & manufacturing cost vs margin & estimated sales), we start development as early as possible, since it can take a few years from "let's do it" to having the URO Parts component available for sale.