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post #31 of 34 (permalink) Old 08-25-2015, 07:04 AM
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Originally Posted by Fonzi View Post
Is that just for a 107? Or would it apply to a 116 1975 450se also?
Good point. In looking at manual (M116/M117 engine manual), the heading says for engines with CIS injection, and then has similar picture for 116 and 107. On quick look, it didn't mention the Djets (EFI). same in Section 1 for compression testing.

I recall Lefdje (73 107) replacing the harness that runs to starter via that terminal strip. And I have had mine partly out . Need to check wire colours and wiring diagrams to confirm if those terminals can be used for bumping.

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post #32 of 34 (permalink) Old 08-25-2015, 07:26 AM
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Originally Posted by MBGraham View Post
Good point. In looking at manual (M116/M117 engine manual), the heading says for engines with CIS injection, and then has similar picture for 116 and 107. On quick look, it didn't mention the Djets (EFI). same in Section 1 for compression testing.



I recall Lefdje (73 107) replacing the harness that runs to starter via that terminal strip. And I have had mine partly out . Need to check wire colours and wiring diagrams to confirm if those terminals can be used for bumping.

Well, I would think that if any terminals can be used for bumping, they would get starting voltage when you start the car. If there are some terminals you want to test. I bet you could just measure the voltage and assure that it goes to 12+ Volts only when you turn the key to the starting position.

It would be great to know, but if you really want to eliminate everything but the starter while trouble-shooting, you probably want to go directly to the starter anyway. In my case, the wire that supplied hot to fire the solenoid melted because I cranked on it so much. If you are trying to bump the engine, it would send current though the same wire. If that wire is your problem (like in my case), you wouldn't be able to bump the engine when the problem occurs. So going directly to the solenoid would be my recommendation for best trouble-shooting. I think it is easiest to reach the starter wires from underneath the car. I recall on my w114, it wasn't too easy to make sure I was getting contact, but once I had the alligator clips attached, I never had to move or remove them, just assure the bump switch wires were out of the way of the exhaust and any moving parts. I left the switch laying on the frame behind the headlight and it never gave me any trouble. Granted, I never did anything more than driving it around the block a few times.

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post #33 of 34 (permalink) Old 08-25-2015, 09:02 AM
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The W116 manual has a much better wiring diagram than I have for my 107.

It shows a terminal C105 which is no doubt the terminal we see in the engine compartment. There are leads from terminals 30 and 50 on the starter. Red and violet, I think. Anyway, for those intersted, here is link to wiring diagram:

Mercedes-Benz Model 116

Testing from terminal strip is no doubt easier. But as Fonzi said, it doesn't eliminate the harness wires or connections.

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post #34 of 34 (permalink) Old 09-11-2015, 10:51 PM Thread Starter
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It depends on how the test was done. My starter would also have likely tested out OK.

When rebuilder took mine apart, there were bad spots on the commutator. If it happened to stop there, no start. Anywhere else, no problem. Hard to do a test that would show that. Especially if not done by an experienced auto-electric shop.

When I had your situation (and it had gone on for at least a year), I just decided rebuilding original starter on an old car was not a bad idea even if that was not the problem. By that time, I had already changed the ignition switch and the neutral switch with no success.

Fonzi's suggestion to connect a start switch that bypasses everything else would eliminate possibility of anything other than starter or solenoid being the problem. If you want to try that I am sure one of us could point you to sources for a cheap hand switch and advise where to connect it.

Solenoid is integral with starter so no point in changing just it - Just change the whole thing if you go that way.

If you go to dealer they may change starter anyway - at great expense! I once bought a new Bosch starter for my 107SL for US$99.00. Had shop install it.
Thanks for the feedback. I had the starter replaced, the shop said it was definitely on its last leg. But after an electrical test the neutral safety switch is failing too and referred me to euro repair shop.
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