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1986 yamaha gearbox issue

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  • 1986 yamaha gearbox issue

    I have a 40 HP, 1986 Yamaha ELJ (2 cycle, 3 cylinder) motor. In fall, found water in gear case oil. After searching for replacements which are available, I decided to try to replace the drive shaft and prop shaft seals. Following the recommendations of Dangar Marine and the precautions of the "hack method," I was able to remove and replace the seals. I did a pressure test using home materials after putting the unit back together and inflated to 15 PSA. Pressure was maintained above 10PSI for 3 minutes, and was 6PSI at 8 min. I wonder what the standards for satisfactory pressure test are? thanks. Peter, east end NY

  • #2
    you should be able to hold pressure for days.
    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

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    What’s behind you doesn’t matter.Enzo Ferrari


    • #3
      I believe there are accepted specifications for pressure testing lower units and the length of time for a leak down....maybe research this more....


      • #4
        The Yamaha pressure test specification is for the lower unit to hold rated pressure for ten (10) seconds. Your unit appears to be just fine.


        • #5
          many thanks for your comments, will continue to research and retest with soap bubbles or underwater.


          • #6
            Originally posted by pbenotti64@gmail.com View Post
            many thanks for your comments, will continue to research and retest with soap bubbles or underwater.
            For what purpose?


            • #7
              Mercruiser (I know) procedure is:

              Pressurize for 7-10 psi, observe gauge for 5 min.

              Rotate d/s, p/s, mo e shift rod while pressurized to check for leaks.

              Pressurize to 15-16 psi, observe for 10-15 min.

              Rotate d/s...etc.

              If pressure drop is noted, immerse in water (or use soap/water), re-pressurize housing and check for air bubbles.


              • #8
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                I normally test 12 hrs or more.-----Do not like to see a pressure drop.-------Testing for 10 seconds, not me.