MSD Assistance Needed

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  • coryhenry
    Lieutenant Commander
    • Jul 2020
    • 156

    MSD Assistance Needed

    I have the 2.5" MSD from Bob and I put it in the water today to do a pressure test. I didn't get any bubbles from any of the seals but I did get bubbles in the seam in the MSD fitting. I have attached a picture that shows the seam in the red box. It was a pretty good volume of bubbles, any thoughts?

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  • RCSubGuy
    Welcome to my underwater realm!
    • Aug 2009
    • 1768

    #2
    Cory,


    Inside that joint is an o-ring. That bulkhead is in two parts to make the modular assembly of a cylinder possible. Now that they're joined, they'll never have to come apart. Grind out the seam a bit and slather in some epoxy. That will take care of the issue once and for all!


    Bob

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    • coryhenry
      Lieutenant Commander
      • Jul 2020
      • 156

      #3
      Perfect, I thought that was the answer just didn't know if it would affect the mechanics.

      Comment

      • He Who Shall Not Be Named
        Moderator
        • Aug 2008
        • 12253

        #4
        Take it apart and check the O-ring.
        Who is John Galt?

        Comment

        • He Who Shall Not Be Named
          Moderator
          • Aug 2008
          • 12253

          #5
          If the O-ring leaks, the water will migrate through the slight gap in the bulkhead faces, into the over-size holes of the securing bolts, conduit bore, and ballast servo pushrod bore -- you will flood the after dry space. If you just slap glue to the outside gap you will negate your ability to fix this thing!

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          But... what the hell do I know?

          David
          Who is John Galt?

          Comment

          • Scott T
            Commander
            • May 2009
            • 378

            #6
            Could you install the O-ring with silicone sealant. Then if you needed to separate them later you could wedge them apart.
            Prepared for depth charges!

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            Comment

            • He Who Shall Not Be Named
              Moderator
              • Aug 2008
              • 12253

              #7
              Originally posted by Scott T
              Could you install the O-ring with silicone sealant. Then if you needed to separate them later you could wedge them apart.
              Prepared for depth charges!

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              That would work. But before resorting to that examine, examine the situation: Was the O-ring out of its groove? Was there some crap in the groove to prevent sealing? Is there a tear in the O-ring? Did some ****ing moron forget to install the O-ring during assembly?...
              Who is John Galt?

              Comment

              • coryhenry
                Lieutenant Commander
                • Jul 2020
                • 156

                #8
                What seals the electrical tube the goes through the ballast tank on each end. Is it just a press fit? I think that is where I am getting a leak.

                Comment

                • He Who Shall Not Be Named
                  Moderator
                  • Aug 2008
                  • 12253

                  #9
                  Originally posted by coryhenry
                  What seals the electrical tube the goes through the ballast tank on each end. Is it just a press fit? I think that is where I am getting a leak.
                  An encapsulated O-ring.

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                  Who is John Galt?

                  Comment

                  • RCSubGuy
                    Welcome to my underwater realm!
                    • Aug 2009
                    • 1768

                    #10
                    I find that gluing one end of the conduit permanently to a ballast bulkhead is a good idea. If you constantly push/pull the cables in and out, it's likely that the conduit can snag and get pulled in one direction or another, parting ways with the seal and causing a leak. If you glue one side permanently, you can still disassemble in case of massive internal repair/refit, but the conduit won't shift on you.

                    Bob

                    Comment

                    • coryhenry
                      Lieutenant Commander
                      • Jul 2020
                      • 156

                      #11
                      That is exactly what I have done, thanks Bob.

                      Comment

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