Today was kind of a damp day here, plus I finally got around to cleaning the frame under the steering pump. In doing so I carefully used high pressure only on the affected area, careful not to douse any electrical components.

As I sat there with the engine idling I could hear a steady pop, pop, pop, which sounded like a spark going to ground. I started checking the wires (which appear to be original) and could not find any arcing. But when I looked into the spark plug recess at #8 I could see the spark going to ground. The spark looked like it was coming from under the resistor end.

Is this a sign of a bad resistor end, or is it due to damp conditions, made worse by adding more water? Examination of the inner face of the resistor end shows some burn, which leads me to believe this has been on going, although today was the first it was bad enough to hear.

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Mike Tangas
73 280 SEL 4.5

Hi Mike,
I would guess that the resistor end is bad. But you can check the wire with an Ohmmeter. The ends are either 1K or 5K (read the markings on it). That should tell you what you need to know.
Regards,
Randy D.

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W.R.Durrance
ASE Master Tech
Mercedes Tech 21 Years
68 250SE
68 SAAB 96 Ice Racer
69 300SEL 6.3
70 300SEL 3.5
81 300TDT
W.R.Durrance Engineering

OK, sitting here with the resistor end in hand. There are no markings on it other than a "6" molded in the lip at the wire end. With the ohmmeter set at 20K, I get a resistance reading of 5.24, I get no reading at lower settings (at higher setting I get 200k - 5.2, 2000k - 005).

I'll see if Franz, my local MB tech has a good one off the parts car for comparison.

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Mike Tangas
73 280 SEL 4.5

The resistance can check out OK, but if spark bleeds thru & you can see arching then a new one is needed.

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MERCEDES BENZ MASTER GUILD TECHNICIAN (6 TIMES)
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. Shopforeman
190E 2.3 16V ITS SCCA racecar

After putting everything back together I ran the engine to check for arcing. No arcing at all, tried wiggling the wires and trying to move the resistor end only thing I didn't try was moistening the area again. I will change the end, as M.B.Doc says, since the arc did bleed through. We are starting the rainy season and the damp conditions are sure to aggrevate the problem.

While I had the ohmmeter out, I also checked the resistance on the plug wire. Again at 20K, the wire showed resistance at 1.18 ohms and as before, no reading at lower settings.

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Mike Tangas
73 280 SEL 4.5