Len Sokoloff / email@example.com / 1959 220S cabriolet
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When it comes time to replace the coil in your Mercedes-Benz Ponton, which replacement should you use? I was not sure, so I contacted Randy Durrance who had been working with Mercedes-Benz ignition systems for 25 years. Randy, without hesitation, said I needed to use the Bosch red coil, which has a Bosch number of 00013 or 0 221 119 030.
He indicated that I should avoid the Bosch blue coil because production for the blue coil has moved to Mexico and he has experienced some quality control issues with these particular units.
He said that the red coils are now made in Brazil but they have not suffered any degradation in their quality. By the way, the red coil is not really red anymore, but as you can see from the photo, it has a couple of red stickers on it. The output of the red coil is more than twice the output of the standard black coil.
With the Bosch red coil, you should use a resistor of 1.8 ohms if you are still using points. With an electronic ignition, the resistor is not needed. My Ponton already had a 1.1 ohm resistor in it. After talking with Randy about it, I decided to try the new coil with the resistor I currently have in my car. There typically is some leeway built into the suggested resistance numbers, so my slightly under-rated 1.1 ohm resistor should work sufficiently well. If there is a problem with it, the only thing that will happen is I might go through a set of points a little faster than with the 1.8 ohm resistor. Randy suggested that I continue to run the car at the factory specifications and possibly consider opening up the plug gap just a bit. This might improve the idle quality a bit and increase the response to about 2000 rpm.
If you prefer to use a Bosch coil that is a direct substitute for the OEM coil, the original Bosch number was TK 12 A 10. The original Mercedes-Benz part number was 000 158 07 03. I believe the modern day equivalent Bosch number is 0 221 102 001. With the above information, you should be able to obtain the coil from any Mercedes-Benz dealer or Bosch distributor.