1958, 5.5 Hp Johnson CD-15 water pump advice

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  • September 13, 2026 at 9:12 pm #328395
    LARRY CATON
    Participant

      US Member

      I have a 1958 CD-15 with a blown up powerhead.  I bought a “junk” 1956 CD-13 that was missing the transom bracket.  The CD-13 had literally sat in a barn for 20 years, but with fresh gas it fired right up.  Now I’m trying to decide how to make these motors into a functional outboard based on signs of wear & tear.

      The CD-15 had been serviced by a pro over the last decade, so I figured it would be in better shape.  I was surprised to see that it has the newer (model 323596) water pump housing.  I hadn’t seen one of these pumps before, and was surprised it doesn’t use the “water seal” on the driveshaft.  The driveshaft is scored where I presume it rubs on a seal at the top of the pump housing.  I was also surprised by how small the impeller is compared to the original.

      Is the 323596 pump really an upgrade?  Or should I use the originally specified 303442 pump housing?

      The 303442 housing and wear plate from the CD-13 are still usable, and I have a spare impeller.  I’m thinking that the scoring on the driveshaft would be covered by the water seal, and therefore not rub on anything.

      I could use advice if one option is better than the other.

      Thanks!

      1956 Johnson 15 Hp, FD-10
      1957 Johnson 5.5 Hp, CD-14
      1958 Johnson 5.5 Hp, CD-15

      September 14, 2026 at 12:29 pm #328423
      Don
      Participant

        US Member

        OK, familiar with the two styles but not sure I understand just what wear you are describing.   The original style aluminum housing pumps are fine provided the impeller housing is not worn/grooved/pitted, which will degrade pump performance.  If the housing is worn, you may as well “upgrade” to the newer style.  Trying to find a new/decent aluminum impeller housing is tough these days, most sellers want big bucks for actual NOS parts….

        Post more pictures if you can showing the wear you are worried about.

        September 15, 2026 at 5:37 pm #328499
        LARRY CATON
        Participant

          US Member

          I think I answered my own question.  The close up photo shows scoring on the driveshaft where it rubs on the “upgraded” pump housing.  Testing in a bucket showed that water leaks out around the shaft. This pump needs a new impeller and wear plate.  Spinning the driveshaft with a drill showed that in its current condition it doesn’t send water very far (see picture).  The original style pump’s impeller needs replacing, but it’s still flexible.  Testing with the drill, it sent water 10 feet away from me.  I already have a new impeller for the original style pump, so I figure that’s the pump housing I should use when making the two outboards into a functional one.

          There’s about 3/16″ of vertical play in the scored driveshaft.  I don’t know if that’s normal, and will be taken up by the spring pressure at the top end.  The other unit has little to no vertical play in the driveshaft.  Both of these have water in the gearbox, so I guess I’ll learn more once I open them up.  I replaced the driveshaft, shift rod, prop shaft, and spaghetti seals on my FD-10, so I’m guessing it’s going to be the same basic procedure.  Hopefully, one lower unit will be in obviously better condition than the other.

          1956 Johnson 15 Hp, FD-10
          1957 Johnson 5.5 Hp, CD-14
          1958 Johnson 5.5 Hp, CD-15

          September 15, 2026 at 5:41 pm #328508
          Buccaneer
          Participant

            US Member

            You should be able to start your own fire department with that pump!

            Prepare to be boarded!

            September 17, 2026 at 11:27 am #328654
            Don
            Participant

              US Member

              OK, that scoring on the driveshaft is not going to hurt anything.  There is not actual seal on  top of the water pump on these engines, so it is normal for some water leakage in that area.

              As for the vertical play in the driveshaft, these are two piece driveshafts so that upper driveshaft can be pulled right out of the gearcase, I would not worry about any vertical play/slop.  You mention that there is water in the gearcases which does bring up another trouble area, which is the shock absorbing spring in the lower driveshaft.  These things get rusted when exposed to water, then they stretch out pushing the lower driveshaft upwards enough so it jams against the lower bushing surface of the upper bushing/seal.  So, you will want to inspect this area closely if you pull the gearcase apart.

              Both pumps look like they are working just fine….

              1 user thanked author for this post.
              LARRY CATON
              September 17, 2026 at 7:41 pm #328669
              JACQUES
              Participant

                if found broken the shock absorber can be tack welded 6inch 11/16 as i recall ….just use a brass  drive/shear pin instead

                Joining AOMCI has priviledges 🙂

                1 user thanked author for this post.
                LARRY CATON
                September 21, 2026 at 7:02 pm #328888
                LARRY CATON
                Participant

                  US Member

                  Interestingly, the aluminum pump housing was pitted and scored, primarily on the inner horizontal surface –the surface where the top of the impeller might rub.  The inner walls of the housing had some pitting and wear, but not as much as on top.  I figured I had nothing to lose, so I scrapped the rough surfaces with a single edge razor blade.  I also snapped a box cutter blade in half so it would fit inside the housing.  I held that blade with Vise-Grips and really went at it.  The scraping produced piles of aluminum dust and small shavings in the housing that I vacuumed up.

                  I kept scraping until all of the pits and circular scoring was gone.  Then I took a rectangular oil stone (for sharpening a pocket knife), and used the end of it, plus some motor oil, to polish the interior.  I was surprised by how far that pump shot water down my driveway –10 feet!

                  I’ve got to replace the driveshaft, shift rod, and gearcase seals, so it will be awhile before I know how well it works in actual use.

                  1956 Johnson 15 Hp, FD-10
                  1957 Johnson 5.5 Hp, CD-14
                  1958 Johnson 5.5 Hp, CD-15

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