54 Johnson RD15A top seal (still) leaks

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  • September 16, 2015 at 8:35 pm #24033
    Mumbles
    Participant

      You don’t need a drill to spin the motor over. In the video, I removed the plugs and ran the flywheel nut down and turned it with a wrench. There’s no danger of melting an impeller at that speed! Fuel mix works good to if you don’t have any oil handy.

      September 17, 2015 at 11:16 am #24083
      olcah
      Participant

        US Member

        Thanks fleetwin and Mumbles. I will try the test and report the results. Need to get to the bottom of this somehow and sure would like to avoid splitting the crankcase if possible.

        September 21, 2015 at 7:07 pm #24326
        olcah
        Participant

          US Member

          9/21/2015 Did test of RD-15A seal. Rotated shaft with socket wrench manually. Spark plugs removed and the air connection to the intake was plugged with a short length of hose with a drill inserted. I had wiped off the top of the motor and the seal cavity then added the oil. I also removed and checked the carbon and square ring and put them back before the test. All solid and good. The crankshaft bearing is tight and rolls smoothly. .
          Used blue Walmart TCW3oil and noticed small bubbles at forward end of the seal. I saw the bubbles when the shaft key is generally to port as in the picture above. Looked like they probably were from the vertical drain slot. To check I removed the seal spring and bottom washer and left the carbon seal in place.
          Rotating the crank shows big bubbles come out of the vertical slot when the crankshaft key is in the position shown in the first photo.
          During the test oil was constantly draining down so I had to keep adding. I looked throough the carb throat at the end of the test and saw blue oil drip on the face of the reed valve plate so things were draining normally

          It looks like air from the crankcase pushes oil out of the vertical drain slot, at least when the engine is not running. I can see no way to fix this and I have a 1954 Evinrude with the same symptom – oil all over the top of the engine and getting into the mag plate. The 1955 and up engines use a conventional seal. Did the factory recognize this problem? Is that why the redesign? Could I remove the carbon seal and then use a seal for a 1955 engine?
          Thank you.

          September 21, 2015 at 7:29 pm #24328
          frankr
          Participant

            A few things wrong with your test. For one thing you aren’t holding the carbon seal down as tight as it normally would be. Secondly, when it isn’t running, intake vacuum is not sucking the oil down to the manifold. And of course, we have no way of knowing if the bearing is loose in the crankcase (heck, somebody may have even left the dowel pin out–or didn’t have it aligned).

            September 21, 2015 at 7:40 pm #24330
            olcah
            Participant

              US Member

              Frank, I agree with the problems that you point out, yet if air is coming out the vertical drain tightness of the carbon does not matter. That would mean that when starting there would be some bubbling. (no vacuum). Do you have any take on why the redesign in 1955 or if a 1955 seal might be used? (Why redesign if the original arrangement was OK?)
              Thanks.

              September 21, 2015 at 7:47 pm #24331
              fleetwin
              Participant

                US Member

                OK, yes it is difficult to evaluate with this style seal/drain system.
                I may have to change my opinion on whether or not that crankcase has been split. Those top two crankcase bolts DO look like someone has had a socket on them. Do the rest of the crankcase bolts look like they have been disturbed also?

                September 21, 2015 at 7:53 pm #24335
                olcah
                Participant

                  US Member

                  I put a wrench on them on the off chance they would move -I know- that would be too easy. They didn’t move at all. The paint was good before then. None of the other crankcase bolts have been messed with.

                  September 21, 2015 at 8:23 pm #24338
                  olcah
                  Participant

                    US Member

                    Could a leaking reed valve push air into the seal?

                    September 21, 2015 at 9:09 pm #24340
                    fleetwin
                    Participant

                      US Member

                      A broken reed could create pressure into the recirc tube. But, didn’t the motor run OK before, except for the oil leak? How about trying a new carbon seal/oring?

                      September 21, 2015 at 9:22 pm #24342
                      olcah
                      Participant

                        US Member

                        Appreciate the comment. The motor ran excellent and idled nicely before the oil got into the magneto. I replaced the carbon with new last winter and used a new square ring. I inspected them today and they look fine. When I took the seal apart previously, there was very little oil below the carbon. Must be missing something, but to have two motors both with new carbons and the same problem..

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