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flywheel magnets test what is it ?

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  • flywheel magnets test what is it ?

    Well, folks i just want to know if there is a test for the flywheel magnets , for strength. If there is a test for the fly wheel magnets , what is it and how is it done ?


  • #2
    Re: flywheel magnets test what is it ?

    I have a magnatometer that I bought at a garage sale. I also have a book on automotive electrical & ignition systems printed in 1926 that shows this very instrument & how to use it. You place the heel of the instrument on the magnet, and it reads the pull in pounds. The book say's that a good magneto should show 25# of pull.The OMC magnets in flywheels that I have checked show 30-35# of pull. Keep in mind that this is an old instrument, and information taken from an old book. It would be fun to know how this compares to the newer instruments. I have never seen another instrument like it, new or old.Nor have I ever seen what the pull should be on modern magnetos. I hope someone can tell us.

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    • #3
      Re: flywheel magnets test what is it ?

      The old timers way of checking magnet strength in smaller outboards was to "dangle" a screwdriver using the thumb and forefinger to hold it about 1" from the mangets. The force should pull the screwdriver in at that distance. In the old old days, we had to recharge the magnets with a Steven's machine.

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      • #4
        Re: flywheel magnets test what is it ?

        Well, that is informative and interesting. I have a 1996 115 hp johnson ocean runner that has weak magnets in the fly wheel. Johnson / evinrude do not show replacement magnets. Is it possible that some other magnets could replace these or that i could remove and recharge these magnets. We installed a new fly wheel from another engine and get plenty of ignition spark, but that fly wheel is not for sale. thanks

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        • #5
          Re: flywheel magnets test what is it ?

          Flatsman! The magnets in your flywheel are cast in,with the exception of the trigger magnets for the ignition,which are held in a ring that is held to the flywheel hub with epoxy. I know of no way to recharge these magnets. As Seahorse said, Stevens Instruments made a charger. I have seen photo's of this charger in early OMC manuals. It looks alot like an old electric hot plate. I have really never run across a flywheel with weak magnets, and I believe this is quite rare. The only thing I know about magnets is, they will not tolerate exteme heat, or a sharp blow. If you have weak ignition with your wheel, check and see if the inner magnet on the hub has slipped. This is the one held with epoxy. I have run into this problem, but that caused more of a timing problem.Another thing you might check is to do a running voltage test on your charge coil. It could be marginal with your wheel, and the other wheel is just stong enough to help.

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          • #6
            Re: flywheel magnets test what is it ?

            I didn't give it a sharpe blow nor did i have to heat it up ----an what i read about magnets does not suggest that they will die down that much --with that said we put a new power pack and stator on with the old fly wheel and it would barely give a spark ----we place the new fly wheel on with the old power pack and old stator and it worked just fine ----but i will check the magnets for slippage . thanks --most interesting problem isn;t it

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            • #7
              Re: flywheel magnets test what is it ?

              A different flywheel is your only fix. In over 40 years of OMC servicing, I've only seen a handful that either had weak magnets or no magnetism at all. I've been told a bad regulator can ruin magnets if it shorts internally and 12 volts heat up the stator. Was there any melting on the black coils on your stator that looked like tar dripping?

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              • #8
                Re: flywheel magnets test what is it ?

                If these are the magnets that are glued in place, it ie very easy to install these incorrectly, if they were loose and reglued. Each magnet has a north south pole, if you install 1 or 2 of the 6 magnets backwards, you will have weak or no spark. The alternator output will also be low if the magnets are weak or intsalled backwards.
                Help somebody every day, if you can.

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                • #9
                  Re: flywheel magnets test what is it ?

                  Only the 35 amp systems on the big block motors with external flywheels have replacable magnets, not on a 115hp.

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                  • #10
                    Re: flywheel magnets test what is it ?

                    I am looking at a 1992 70 Hp, with a cast iron/steel flywheel that has glued in magnets. 1995 40 hp has glued in magnets.
                    Help somebody every day, if you can.

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                    • #11
                      Re: flywheel magnets test what is it ?

                      The factory only makes replacement magnets for the 35 amp flywheels.

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                      • #12
                        Re: flywheel magnets test what is it ?

                        Here's a guy who figured out a way to recharge the flywheel magnets on a model T. Looks interesting - basically using a field coil and 3 auto batteries in series as an electromagnet http://ccmtc.www6.50megs.com/TipMagnets.html
                        It's all about the tools.

                        "If the ocean is glass flat and the sun is shining, you open up the special memory compartment of your brain and start recording the smells, sounds, sights and feelings." -- Philster

                        "Poets talk about 'spots of time,' but it is really fishermen who experience eternity compressed into a moment. No one can tell what a spot of time is until suddenly the whole world is a fish and the fish is gone. I shall remember that son of a b**** forever." -- N. Maclean

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                        • #13
                          Re: flywheel magnets test what is it ?

                          Well, I appreciate the response on this and hope that more may come. This same flywheel is on the later models also. Also the stator didn't have any tar or anything dripping from the coils. The coils however are darker in color than the new one we tried out. But when we installed a new one for a test it functioned just fine. Could it(the stator) still be a problem . Also while I am thinking about this , what if I place some very strong magnets on the flywheel magnets , will the charge pass over the the weaker magnets?Thanks

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                          • #14
                            Re: flywheel magnets test what is it ?

                            Flatsman, I was thinking along the same lines. We used to run a strong permanent magnet along the shaft of screwdrivers a few times and magnatise them. If the magnets in the flywheel are not physicly damaged, why not try the same thing.You can get a strong magnet from a hardware store or Home Depot. Make sure the polarity is correct. You should not feel any pole opposition (like poles repel). And stroke the flywheel magnets a number of times in the same direction. DO NOT rub back and forth>>>rub in one direction & lift magnet clear at the end of the stroke. Go back and rub in the same direction, over and over again. You could use a cheap compass to check the polarity with the other magnets in the flywheel.You could even use the compass and ruler to gauge magnetic flux strength. See how close you need to get to a known GOOD flywheel, to effect the compass. And then try and duplicate with the questionable flywheel. It should give you a relative reading I would think.>>>You have nothing to loose, try it. Good luck

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                            • #15
                              Re: flywheel magnets test what is it ?

                              Yeah , you are right there is nothing to loose. This must truely be a rare happening on outboard engines or maybe weak magnets are over-looked sometimes.

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