Magnetos and water

Rex in Australia · Jan 27, 2013

Hi guys, after a disasterous wet rally weekend, I have two
tractors with wet magnetos still on the site.
That got me thinking, does anybody have ideas of a treatment
to these old magneto caps that are porous and take in water?
Any kind of sealant that they could be treated with?
Cheers,
Rx

robgIN · Jan 27, 2013

try spraying WD40 inside the cap and wherever you can get it give it a few minutes and if you have an air tank or some way to blow air in that will help too. WD40 was developed for the military in WWII to dry out ignitions in all sorts of vehicles and aircraft. The WD stands for water displacement, I'm sure it has changed some over the years but it still works, I have used it for that purpose on a couple of wet F4 mags successfully.

rocko · Jan 27, 2013

Never knew that. Learn something every day. Gotta say that I never would have tried it in any thing electrical tell I read it here. Thanks. Rocky.

Charlie M · Jan 27, 2013

I was caught in the rain more than once as a kid on our A with a mag and had it just quit when it got wet. Went back the next day after it stopped raining and it started right up.

60 acre hillside · Jan 27, 2013

I see a lot of them at shows with plastic bags tied over them.

Texasmark1 · Jan 27, 2013

Ditto on the WD-40. We are talking about the original product in the blue and yellow can, not some of their current derivatives in different colored cans.

Spray it and leave it dripping wet. It displaces water and allows high voltage circuits to operate in humid/wet environments.

Mark

Janicholson · Jan 27, 2013

When dry (and before spraying with WD40) they can be coated inside and out with clear acrylic spray. Use several light coats to reduce runs. Jim

Greg K · Jan 27, 2013

If you don't have any WD-40 Starting fluid (ether) will work. Make sure to let the cap air out!!!! before putting it back on or you will learn about the other thing that ether does

and you will be looking for a new cap.

Motorcraftman · Jan 27, 2013

Spraying armorall on the Inside of the cap also Works well. Larry KF4LKU

JD Seller · Jan 27, 2013

I second the use of WD-40 to dry a wet one out. I usually spray everything under the cap and then blow it out with compressed air. If you do not have compressed air around usually just wiping them out with a rag is good enough. The WD-40 will bind with the water and then you can blow it out better.

As for when they are running correctly. If I know I am going to have one set out in the rain I cover them up with a plastic bag. Used bread sacks or plastic shopping bags work well. If they are inside I do not cover them with plastic as it will make them sweat.

Ted in NE-OH · Jan 27, 2013

Also make sure you have a good gasket between the cap with spark plug leads and the main body.

Rex in Australia · Jan 27, 2013

Thanks fellas, I'd had a pretty good run up until now, but the weather turned really bad. I knew about the wd40, and had some in the car this morning on the way down there, but the road was closed. I'll also try the sealer coats when it dries out again I reckon. The caps are quite old and porous.
Best rain we have had for some time, measured around 10 inches over the last few days. Just a shame it had to be over the rally site! But the rain is still a blessing. We really needed it.
Rx

Pete in MD · Jan 27, 2013

WD-40 was created by the Rocket Chemical Co. in San Diego in the mid 1950s.

Paul from MI · Jan 27, 2013

I was driving my H pulling wagon loads of visitors at an open house on a local dairy farm when a sudden shower popped up. I immediately took off my cap and covered the magneto, and continued the tour. One of the visitors later asked where I learned to do that. I told her about 60 years ago, the hard way! Wet head is easier to dry than a wet mag. Once the rain stops the cap can be dried with a hair dryer.

Anonymous-0 · Jan 27, 2013

what about wire dryer - like what is used for spraying spark plug wires?

47farmallM · Jan 27, 2013

i have a old piece of inner tube that i got tied around my mag, keep the rain shedded off it, never had a problem yet

Jon Hagen · Jan 27, 2013

I dont know how effective it is, but a lot of mag equipped tractors at the Rolag show had the mags covered with aluminum foil, formed to the shape of the mag including cap and some part of the wires.

RalphWD45 · Jan 28, 2013

I drove my 76 dodge pickup up on top of Skate mountain, above Packwood Wa., in the early fall, a few yr's ago. I saw a alpine lake, and stopped to walk down and let my black lab play with some wild ducks on the lake. Upon returning to th truck it refused to start. after looking at it I removed the Dist. cap and found it full of beads of water. I had heard of using wd40 to dry out such things, so I grabbed a can from the tool box and sprayed the cap interior, and the electronic pickup inside. I replaced the cap, and started the truck. It ran fine. something about the humidity at that elevation, that caused condensation inside of the dist cap!

LA in WI · Jan 28, 2013

On a ride with the Great Eastern Iowa Tractorcade there was an H Farmall that wouldn't start after some rain. A guy walked up and sprayed the open mag cover with silacone until it was dripping wet, then closed the cover and as he hit the starter I saw a little flash and some smoke came out the mag...the tractor motor was running just fine.
LA in WI

Down under farmer · Jan 28, 2013

Not the only one rex lucky mine are deisel they are still there to. I heard there was a foot of water running through the back of the showgrounds today but not up where the tractors where could be a day or to before we can get them out

Nancy Howell · Jan 28, 2013

If they're just sitting on display and not running and getting warm, you might pick up some of the small plastic elasticized covers to go around them to keep moisture out.

You can find them at a grocery store where they have the plastic food storage containers.

gene bender · Jan 28, 2013

I found out i had the problem cause when it was wet you could feel spark by touching the top. So i made sure it was dry after letting it set in the sun for a couple days. Then i blocked the holes with some cotton placed deep covering the contac . Then using black gloss spray paint gave it several coats making sure each coat was cured. Now its in service and running water on it doesent seem to be a problem anymnore. Not that im against getting a new one just wanted to see if the idea would work. Its worth a try as it worked for me.

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