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OT - painting exposed magneto coil laminations?

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  • OT - painting exposed magneto coil laminations?

    I've been chasing a no-start problem on a Kohler magnum twin (M18). I just received a low cost replacement coil and the laminated core is not well protected. I'm wondering if I should spray the exposed plates with "something" to help prevent rust? This is a magneto system. One spot between the laminations is not fully sandwiched - possibly due to getting banged in shipping (flimsy box in a priority envelope), and not the greatest job on pinning the plates together.

    The coil sits under the cover but all of the air sucked through the engine blows over this coil, so there will be a tremendous amount of debris and dust. My understanding is the laminations are supposed to be insulated from one another. Maybe spray it with bed liner? With primer? There is apparently some oil on the laminations, based on the stains on the box. So, remove the surface oil to spray something else? Or spray and pray?

    These cheap coils are about $23. A factory coil locally is $250, $200 online. The photos of the oem coil look similar - though I'm not sure the recent units are built as well as the good ole days.

    Anyway, just wondering what personal experience says about this. At the low price, I could just replace them every year or two. But you also just want the thing to work.

    This is an example of a cheap coil:

    Click image for larger version  Name:	kohler.coil.jpg Views:	0 Size:	86.4 KB ID:	1971526

  • #2
    I don't think any of mine were ever painted or even varnished. The engine heat will keep rust down fairly well.

    You could varnish it, I don't think I would spray paint it. Brush coat the lams if you like.
    2730

    Keep eye on ball.
    Hashim Khan

    Everything not impossible is compulsory

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    • #3
      Originally posted by Glug View Post
      . . .My understanding is the laminations are supposed to be insulated from one another. . .
      Most transformers have the laminations shellacked, but they are also welded across at a couple of points. I read somewhere why that is, but can't remember. Jerry?

      Southwest Utah

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      • #4
        They are basically there for just their iron content --- critical area's are where the gap is set towards the flywheel and also you don't want the place where they are inserted into the coil pack to swell between the plates too much or it could upset the primary or secondary windings...

        paint or varnish could end up being a double edge sword as if you get most of it sealed but "not quite" it could then end up holding moisture and making things rust 24/7

        just run it --- we will all most likely be dead before it gives a problem....

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        • #5
          Originally posted by chipmaker4130 View Post

          Most transformers have the laminations shellacked, but they are also welded across at a couple of points. I read somewhere why that is, but can't remember. Jerry?
          Transformers are commonly varnish coated in a vacuum pot, to keep things from vibrating and for rust protection (there is also some heat conduction outward provided). The welding is a "cheap substitute" for using insulated through-bolts. The bolts are to hold the laminations together.

          The laminations will not be effective if they "broom-out" enough to cause gaps between them. "E" and "I" shaped laminations form a complete enclosure. They are alternated with the E alternately ponting up and down. The magnetic path is partly from the end of the "E" into the "I" that is across the open ends, but a lot of it is sideways from one lamination into the adjacent one. So if they separate, they will not have a good magnetic path.

          The welding shorts together the laminations, (they are normally insulated by oxide) and increases losses by offering a closed circuit that can have current induced in it. But it is cheap to do. A good low loss transformer won't have welds.
          2730

          Keep eye on ball.
          Hashim Khan

          Everything not impossible is compulsory

          Comment


          • #6
            Thanks for the suggestions. I put it on, it started right up. I'm not sure if I'll spray it with something now that it is mounted. Comparing it to the original, it doesn't look all that different and has worked for many years. I plan on having a spare on the shelf, so I'm not as worried about it.

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            • #7
              Yeah I guess depends where You live also Glug --- would not be an issue where im at, no harm with hitting it with some light oil and wiping it down --- it will soak between the plates and keep things from oxidizing for quite sometime...

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              • #8
                Originally posted by J Tiers View Post
                I don't think any of mine were ever painted or even varnished. The engine heat will keep rust down fairly well.

                You could varnish it, I don't think I would spray paint it. Brush coat the lams if you like.
                A lot depends on storage conditions. Damp barn or shed etc.
                I've seen rust swell the laminates due to wet storage conditions.
                I've seen some motors where the laminates are shellacked, and some plain.

                JL..............

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                • #9
                  Because of high humidity in my area, I use LPS3 preservative https://www.amazon.com/LPS-Premier-R.../dp/B000SKWQQS

                  A shot on the laminations and a shot on the flywheel magnets keeps them from flash rusting. I spray it on, wait for it to thicken up and then wipe off the excess with a rag. It works pretty good and I haven't had to go back and sandpaper off a coil or magnet face since using it.
                  I just need one more tool,just one!

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                  • #10
                    Originally posted by JoeLee View Post
                    A lot depends on storage conditions. Damp barn or shed etc.
                    I've seen rust swell the laminates due to wet storage conditions.
                    I've seen some motors where the laminates are shellacked, and some plain.

                    JL..............
                    Yes I too have seen the rust get into the laminations and swell them to the point of destruction.
                    As a matter of fact I have recently replaced several Chrysler Corp. ignition coils like the one shown below that were swollen so much that they cracked the epoxy that seals and holds the coil together. Once cracked moisture and dirt finds it's way into them rendering the coil useless as the high voltage will soon carbon track itself to death internally.
                    I usually give the new replacements a good heavy coat of paint so that they will live a little longer.

                    ​


                    image widget
                    Home, down in the valley behind the Red Angus
                    Bad Decisions Make Good Stories​

                    Location: British Columbia

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                    • #11
                      Can you pull the windings off the new magneto and reuse the old magneto laminations?

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                      • #12
                        I would go with the simple oiling of the laminations and the flywheel. A light spray like the LPS3 mentioned above or any oil with excess wiped off. Paint or varnish won't hurt, but it may actually trap moisture and make things worse like A.K. said.
                        Robin

                        Happily working on my second million Gave up on the first

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                        • #13
                          Originally posted by SLK001 View Post
                          Can you pull the windings off the new magneto and reuse the old magneto laminations?
                          Doubtful, but it depends on the design.
                          If if the coil is wound around the laminations and then sealed it's going to be tough. I've never heard of anybody attempting it.

                          JL.....

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                          • #14
                            A vacuum impregnation would seem to be a reasonable way to protect the thing. I would use a thin epoxy as it's better able to penetrate the windings and voids in the structure.

                            Short of that, I would bake the item for some time, then apply epoxy to the exposed windings, hoping that some would make its way into crevasses and gaps to help seal it. Besides mounting holes, the only places on the coil assembly to worry about would be where the gap in the magnetic field path is. Make sure you don't create a build-up there, and you should be good to go.
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                            • #15
                              There are no exposed windings. The problem is the core. A coat of spray paint preferably high temperature will keep rust out for a long time. It should be degreased first because it already has some light protection otherwise it would show some rust already. We had to store new transformer laminations in a very dry place otherwise they would be ruined by the time they went to use. After assembly and varnish impregnation then, there would be no problem.
                              Helder Ferreira
                              Setubal, Portugal

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