Home Forum Ask A Member 1938 Bendix TMD spark issues?

Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
    Posts
  • #283438
    Buccaneer
    Participant

      US Member

      I got back to the Bendix after taking a “time out”
      over frustration on ignition issues, having weak
      spark.

      I had tried two different after-market condensers
      that tested at .23 mfd.

      Today, I installed a .15 capacitor, and reset the points
      again. It had seemingly good spark at the plugs, so
      I squirted in some fogging oil.
      It did fire a “little”. Sprayed some more, and it fired
      less. Gave it a shot of ether, and fired a tiny bit.

      I pulled the port spark plug, and it looked a little “wet”.

      With the plug out, attached to the plug wire, and grounded,
      I pulled the engine to check for spark again on the port
      cylinder, and to my surprise, it ran a couple of seconds.

      The spark on the port cylinder still looked plenty good,
      so I re-checked compression. Surprisingly, the port
      cylinder had higher compression at 73 psi, and the
      Starboard 67 psi. The compression was probably higher
      on the port from the “unburned” fogging oil.
      Originally, the compression was within two psi between
      cylinders.
      If the compression is adequate, then one has to think “spark”?

      Coils tested good on my Stevens tester, and via the Bendix
      manual Model T coil setup.

      I did notice before I put the magneto back on, that the
      rotating magnet had twice as much pull
      on one half of the magnet than the other, using a screwdriver.
      It evidently has two opposing magnets as it’s a twin opposed
      outboard.
      I know magnet strength is debatable as far as “starting performance”
      on outboards, but at this point, I have no other ideas!
      How about you? Thanks.

      DSCN8600

      DSCN8710-1

      Prepare to be boarded!

      #283449
      stanley
      Participant

        US Member

        I’d think the spark on at least the one cylinder should be enough to get it to run.Maybe just try getting it to run on one cylinder and isolate the “bad side”?

        #283450
        Buccaneer
        Participant

          US Member

          I’d think the spark on at least the one cylinder should be enough to get it to run.Maybe just try getting it to run on one cylinder and isolate the “bad side”?

          Stanley, are you suggesting to turn it into a single cylinder engine,
          or hope the spark or other ailment, will improve if it’s ran for a while, lol.

           

           

          Prepare to be boarded!

          #283452
          Tubs
          Participant



            I would be leaning towards fuel mixture (wet
            plug) and – or timing, not enough advance.
            Looking through your pictures I don’t see where
            you had the pistons out so stuck rings could
            be the issue if you haven’t checked them
            through the ports..
            If you have a compass pass it across the magnet.
            If the compass changes from North to South you
            have two magnets. If North points to one side
            and South to the other its just one magnet.
            Focusing on the magnet is like driving down
            the wrong road. You’ll never get where you’re
            trying to go.
            Tubs

            A "Boat House Repair" is one that done without having tools or the skills to do it properly.

            #283454
            Tom
            Participant

              US Member

              I looked at one of your other posts and noticed that there is only one primary circuit for two coils.  Interesting, I’ve never seen that on any other motors.  So if both coils are seeing the same primary voltage, then I wold assume that if only one of them sparks, there’s an issue with the other coil.  Have you tried closing down the plug gaps to maybe 0.020″?  Or increasing the capacitance of the condenser?

              Tom

              #283456
              stanley
              Participant

                US Member

                No,I was simply suggesting if it would run on one or the other cylinder you could narrow the problem

                #283459
                Buccaneer
                Participant

                  US Member

                  Yes, the primary circuits are hooked up in series, and I had never
                  seen such a system either.

                  Coils were tested several ways, many times, and always passed with flying colors.
                  Yesterday I switched out the .23 mfd aftermarket condenser with a .15 electronic
                  capacitor, reinstalled the magnet, and reinstalled a non original ground wire
                  between the magneto, and powerhead, which I had previously tried.
                  Reset the points again, and it appeared to have good spark on both old, shorty plugs.

                  I dug out some new NGK plugs and tried them out for kicks, after squirting some
                  gas in the carb. There may be a Christmas Miracle in the works!

                  It looks like the rotating magnet is “off the hook”.

                  VIDEO………
                  https://youtu.be/DxbmXvYkoTY

                  Prepare to be boarded!

                Viewing 7 posts - 1 through 7 (of 7 total)
                • You must be logged in to reply to this topic.