Wow, thank you all for the feedback. With all of this info, I am ready to diagnose!

AC

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'83 240D (W123) 321K miles
250KM Mileage Award
500KM Mileage Award

'84 300TD (W123) 215k miles
250K mileage award pending

I believe it was the short screws holding this piece ( unfortunately loosely) inside the main body of the starter...which were arcing.

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Might just need new battery and or a clean up of ground cables. A hot starter needs all the juice it can get . My 454 Blazer dose what yours is doing in hot weather............

William Rogers.........

My SD has done the same thing. Just happened to my brother the other day at a rest area. I talked him through the hammer procedure on the phone. It worked. It also happened while sitting at school, so I know it wasn't hot then. Will just replacing the solenoid fix it?
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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leathermang, does the manual go on to describe what that switch actually does? I think it merely disengages the cruise control.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Mine did that and I did replace the solenoid.....Never happened again. I changed it about a month or so ago. I kept putting it off until I had to get it towed to my house.

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Audi TT

Rick , it does not say anymore about it....
but as I said earlier .... I don't think it functions as a neutral safety switch in my car... so you are probably right... or my switch is messed up... but fortunately does not fail in the " won't let you start the car" mode...
Most cars are hooked to the brake pedal for that...which would serve for both auto and manual trans in one configuration... so I did not assume it was for the speed control...
Someone needs to look at a good wiring diagram.... LOL

The starter has to pass enough current to energize the "pick" coil in the solonoid. So yes, a bad starter can keep a good solonoid from working (clicking) . And a bad solonoid can keep a good starter from working.

P E H

PEH, ok then that explains my symptoms and sounds like the cause ( which they showed me ) was those inside screws not being tight....

Rick, I looked at the wiring diagram for the speed control.... it is hooked to the brake switch... which is what I would have guessed it should be...

So I don't know what this switch on my clutch pedal does.... because I just tried starting the car in first and neutral without depressing the clutch... and it started for both...

Leather,

The reason solonoids use pick and hold coils is so heavy guage wires are not needed to go to the solonoid and a heavy current terminals are not needed in the key switch. Since the pick coil is energized for only a split second, the lighter guage wires and contacts do not overheat. The hold coil doesn't overheat either. Also there is more current available to the starter to crank the engine.

The pick current goes thru the starter until the solonoid contacts are closed. Then the voltage at the pick coil goes from 0 to +12 volts (because it is connected to the + terminal on the starter) and thus there in no longer any current going thru the pick coil windings I.E. it has 12 volts at each end of the windings. The hold coil which draws much less current has current flowing thru it as long as the key switch is held in the start position.

P E H

Thanks, I know that I am not the only one that did not know that.