Magnetos

Binderson · May 17, 2020

I inherited a 1937 F20 from my dad earlier this year. I am wanting to wash it this upcoming weekend and I vaguely remember the magneto was always covered so it wasn't wet when he washed the tractor. Is there anything special to do this? Would a grocery bag work? What all parts need to be covered not he magneto? Is it just the piece itself or the wires going to the magneto need to remain 100% dry as well? I thought the magneto needs to remain dry but I've also seen videos of guys starting the tractor in the rain and there was no mention of the magneto needing to remain dry.

Thanks for the help!

warbaby · May 17, 2020

Water provides an easy path to ground for electricity so keeping the magneto dry will hopefully keep the water from forming an easier electrical path than the
route down the wires and across the spark plug electrode gap!

The other thing that can wreak havoc when wet is inside the magneto- your points. Get a little moisture in there and you'll have the same problem: a short circuit
to ground that will temporarily disable your ignition system.

Any waterproof bag will help, some water displacing spray can, like WD-40 will help if you get too wet

Binderson · May 17, 2020

(quoted from post at 17:01:19 05/17/20) Water provides an easy path to ground for electricity so keeping the magneto dry will hopefully keep the water from forming an easier electrical path than the
route down the wires and across the spark plug electrode gap!

The other thing that can wreak havoc when wet is inside the magneto- your points. Get a little moisture in there and you'll have the same problem: a short circuit
to ground that will temporarily disable your ignition system.

Any waterproof bag will help, some water displacing spray can, like WD-40 will help if you get too wet

Will I need to cover the spark plugs where they connect to the motor or only the magneto needs covered?

Thank you for the feedback!

Steve@Advance · May 17, 2020

I wouldn't worry about getting the plug wires wet. They will quickly dry.

The concern is getting water inside the mag, where it will get trapped down in the housing where you can't get it out. Then it starts steaming up and condensing under the cap, shorting out the high voltage and corroding the points and other internal parts.

Removing the wires from the cap will make it easier to seal a plastic bag around the body.

Leroy · May 17, 2020

I don't know that mag, just some are easier for water to get inside than others, same as a distributor, if water can get under the cap that is where the problem comes from. Not the wires or plugs

dr sportster · May 18, 2020

Mags are vented so water can get in the vent. Use any plastic bag .

47fivewindow · May 18, 2020

I have had good results with aluminium foil over a plastic grocery bag.

Magnetos

Binderson

Member

warbaby

Well-known Member

Binderson

Member

Steve@Advance

Well-known Member

Leroy

Well-known Member

dr sportster

Well-known Member

47fivewindow

Well-known Member

Similar threads