M.D . grounding switch

Fallon · Nov 10, 2009

Rebuilding the mag on my 1948 MD. The wire from the mag grounding switch has been cut and not attached to the mag. Would like to get it set up right. Do you take off the two nuts at the front end of the intake manifold? And once I do this is their an actual switch that can be changed out. Its hard to see how it is set up in the service manual. Also why would the switch be cut in the first place, and would any harm be done leaving it unattached. Not sure of the purpose of it or how it works. Thanks for any info;

tractorsam · Nov 10, 2009

The switch is attached (internally) to the same mechanism that operates the butterflies in the manifold. It purpose was to ground the magneto when the tractor was running on diesel. Presumably to cut down on point erosion? I imagine it was cut either after it broke or when someone who didn't know what they were doing couldn't get it started and began clutching at straws. Sam

Anonymous-0 · Nov 11, 2009

I also have a 48 MD that had the wire cut between the grounding switch and mag. If you take off the front cover, you'll see the switch and how the wire attaches. Work the gas-diesel lever back and forth a few times to see that the switch moves. Chances are that it is OK. I got a new spark plug wire set from John Brillman and the mag grounding wire is included in the set. (Don't have his number in front of me, but he's in Red Power and also on line.
Replace the grounding wire, make sure your mag is hot, and you should be good to go. My MD had not been run on gas in a long time, but once I fixed all the electrical stuff, it fired right up.

M.D . grounding switch

Fallon

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tractorsam

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Anonymous-0

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