My dad is out of town, and I was supposed to use the 300SD to get some things done to it at the shop. well, I had to come back home for a few mins, and when I went back out to the car, I could not get it to start. I did the usual, I put the shifter in both neutral AND park before each time I tried to start it, no starting. The car has been doing this for a good long while now, and then I remembered what he told me to do if I was ever driving it and that would happen. The mechanic gave him a piece of wire, and told him when it wouldn't start, to put the key into the preglow position, to open the hood, and touch these two outside screws in a row of four located in a plastic rectangular box on the passenger's side with the wire, and the car would start. Well, I don't like doing that, it seems dangerous, and I need to know what the real problem is. I'm thinking it's the starter, but for all I know, it could be something cheap.
Thanks,
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

since you have needed to fool with the shift lever position for some time to get it to start, I would suspect the neutral starting switch. This switch, just aft of the modulator on the left side of the trans, inhibits current to the starter solenoid unless it senses that trans is in neutral or park.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Very likely its the neutral sensing switch on the tranny BUT I had a problem similar to yours, I didn't mind using the short piece of wire to hot start the car (it was VERY intermittent!)
But my wife uses the car occasionally and she is not capable of doing that so I replaced the neut switch. Then, Lo and Behold! the problem still was there

It has since been determined that my starter switch (so-called ignition sw) is probably the culprit, so don't rule that out too as potential source of this kind of problem.
It isn't your starter, after all the car will start OK when you use the jumper wire, doesn't it? so its not the starter motor!

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Is replacing the starter switch an easy DIY project? Is the starter switch considered to be a cheap part?
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

I had the same problem, still do. I put the magic red button under the dash, hooked the button to a Bosch relay and the Bosch relay to the two screws mentioned earlier. The wife was driving the Benz and it stuck her in Austin one night. The next day the button got installed.

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Jim
82 300SD saved from scrap yard, 86 front clip,85 500SEL rear end,86 wheels.

Another option is shifter bushings. If there is enough wear, it may not be moving the arm enough. www.**************.com sells a kit with bushings and a little tool for installation.

If this the case, it would be advisable to get into the habit of using the parking brake or it may not be in the same place you left it.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I posted before that there is nothing wrong with the shifter. It's not rattling or sloppy like my 300D used to me, its shifter is quite firm. I think that it's the starter switch. They don't cost too much, but I don't know how easy the job is for the beginning DIY'er.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.