1975 Johnson 15R75C 15 hp

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  • August 30, 2025 at 8:41 am #299427
    David Bartlett
    Participant

      US Member

      In 1978 I worked for Great Northern Paper Company in Northern Maine during the summer months doing water quality studies on the Penobscot River. We had one of these 15 Johnsons at the time and the mechanics hated it. I was the only member of the team that could make it run.

      45 years later I did a favor for my BIL and worked on one of these for a friend of his. I spent a month undoing a bunch of stuff and chasing my tail. In my case it was a bad fuel pump, and the Amazon replacement the owner put on was just good enough to run in the barrel. A new OEM pump finally fixed it.

      Needless to say, these are one of my least favorite OMC products.  Good Luck!

      David Bartlett
      Pine Tree Boating Club Chapter

      "I don't fully understand everything I know!"

      August 30, 2025 at 9:02 am #299428
      crosbyman
      Participant

        Canada Member

        see diag

        Johnson Cylinder & Crankcase Parts for 1975 15hp 15R75C Outboard Motor

         

        Joining AOMCI has priviledges 🙂

        August 30, 2025 at 12:04 pm #299438
        Buccaneer
        Participant

          US Member

          I looked at the diagram earlier, and looked at the motor again.
          Is the thermostat under the water jacket cover on the head?

          I see nothing obvious otherwise. I don’t think there’s even
          room to pull the water jacket cover off without hitting
          the lower cowling.

          Prepare to be boarded!

          August 30, 2025 at 1:19 pm #299450
          crosbyman
          Participant

            Canada Member

            see part#19  !  should be easy to find..

             

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            August 30, 2025 at 2:05 pm #299454
            Buccaneer
            Participant

              US Member

              Crosby Man, I seen the thermostat on the diagram, but
              not on the motor.
              Photos below.
              Please circle the thermostat and send it back, lol.

              I just got back from the lake with the motor, and it ran great.
              It really scooted my little Alumacraft along!
              I leaned out the low speed needle quite a bit until I got
              a little hesitation opening it up, then went back a little richer.

              DSCN3341

              DSCN3342

              Prepare to be boarded!

              August 30, 2025 at 2:59 pm #299461
              crosbyman
              Participant

                Canada Member

                well I don’t see it but what is that  sylver  circular bulge just left of the lower side bolt   of the cyl head…. is there any chance the thing could be behind a cyl head cover  necessitating its removeval ??

                if not ….I guess the info on marineengine.com  is wrong or your PH  is

                cyl head pic on marineengine.com show a cavity to fit the thermostat on the INSIDE of the cyl. head….    then a cover fitting over it  ??

                Evinrude Johnson OMC 0320495 – Cylinder Head (320495)

                 

                see covering section over the cyl head thermostat cavity

                 

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