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1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

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  • 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

    Over the past few years, purchased all the parts needed to convert a '63 18hp shortshaft to longshaft. Only part I couldn't find was the 5" longer water tube.... So, went to Lowes, purchased copper tube and coupler to match the diamter of the shortshaft water tube. Cut a 5" length, cleaned and sanded, fluxed, and silver soldered the two together using a standard copper coupler. Tested for air leaks and the solder job was tight.

    Reassembled my freshly-rebuilt lower unit (all new seals, rings, bushings, impeller, oil, etc.). It took about 45 minutes of finese to get the driveshaft, shift shafter and water tube realigned. The first attempt yielded the "new" water tube was too long. Removed the L.U. and cut the modified water tube 3/8" shorter. Another 30 minutes I had it back together. Ran in barrell and no water was pumping after about 10 seconds. Shut down and removed lower unit again, found the water tube grommet on the lower end was pinched. Straighted it out and after another 40 minutes, had it back together a 3rd time. Still, no water. I'm absolutely positive the water tube is seated correctely on both ends.

    I dropped the lower unit AGAIN, removed the water pump, housing, & plate and re-inspected the brand new (Sierra brand) impeller. Everything looked good. The driveshaft key was there. So, I then checked the water passages on the block.... Rigged up a water hose to another piece of spare copper... inserted it into the upper water grommet. Water passed immediatey thru the system and exited thru the exhaust port. Just to make sure, I removed T-stat plate & gasket and confirmed water was passing freely there (it was a new T-Stat & gasket anyhow, but I wanted to make sure). With my "test hose" rig, I was able to fire the motor up and it ran fine connected directly to a water hose (with the lower unit still removed). Block was very cool, could leave your hand on it forever.

    Everything looks fine to me. I'm puzzled. This is my 3rd lower unit rebuild on the '58-'72 Fastwin era. I've never had trouble like this. Water in the barrel was the same height as I always run these motors in the past.

    Is there any way to (while the lower unit is removed) test the water pump to make sure its functioning? I'm wondering if the driveshaft key isn't seating at idle? The last "funky" problem like this was the brass center ring of the impeller spun loose from the vanes - kinda like a spun prop. Had never seen that before (another Sierra brand part).

    Any help would be appreciated.

    -Matt in FLA

  • #2
    Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

    You can remove the lower and place in a bucket of water.... spin the driveshaft (as if the motor were running) and see what happens. I have used a high speed drill to spin the driveshaft, just don't mess up the splines!

    If it pumps then you know the issue is with your water tube.

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    • #3
      Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

      Is the lower unit deep enough in the barrel? Water level must be higher than the water pump, as the pump is not self-priming.

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      • #4
        Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

        oK, I got back to this project today. took apart & reassembled the lower unit to midsection & retested. no good, still no water pumping. so, I put just the Lower unit in the water barrel and connected a power drill to the end of the drive shaft. spinning full speed it got NO water. I then took the water pump housing off and put gasket sealer underneath and let dry for 1 hour. retested with drill in water barrel again, And still no water pumping....... what am I missing? What's the next troubleshooting step?

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        • #5
          Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

          And I did verify the key was present on the driveshaft to engage the impeller, which is new

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          • #6
            Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

            Did you have the pump housing completely underwater?

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            • #7
              Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

              Yes. without any doubt. the lower unit is positively under enough water.

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              • #8
                Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                Well, if the key is in place, the only thing I can suggest is a defective impeller. Check the impeller, and make sure the rubber fins are not slipping in the brass hub.

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                • #9
                  Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                  The water intake is free of debris as well right? Check the passage from the intake to the impeller housing. Is the vent hole open on the housing and not blocked? Housing/plate not scored/damaged?

                  Also check that Sierra impeller as mentioned. I have seen MANY fail right out of the package. I only use OEM impellers myself. Kind of a critical piece of equipment.
                  Chris

                  Johnson - Evinrude Top Secret Files:

                  Proudly Dedicating My Time To Antique And Vintage Style Outboards!

                  Comment


                  • #10
                    Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                    Well, I finally got back to this project. I removed the existing "new" water pump and put in another brand-new Sierra water pump kit (without housing). Sealed the base plate to the lower unit too. put unit back in midsection, fired it up, and it worked great.

                    I'm baffled as to why the other impeller & drive key didn't work.

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                    • #11
                      Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                      And I used the Sierra only b/c I already had it in my spare parts bin. will likely pay the extra for OEM impeller in the future.

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                      • #12
                        Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                        The hub may be spun, did the key cut a groove in the hub? Some just aren't the right dimensions!

                        I have a box of almost 50 Sierra impellers that are NFG and were brand new put in by owners that I pulled out and saved. I only use OEM impellers in all of my motors, and will only put OEM in for others. Sometimes they work fine, but.....sometimes they don't.
                        Chris

                        Johnson - Evinrude Top Secret Files:

                        Proudly Dedicating My Time To Antique And Vintage Style Outboards!

                        Comment


                        • #13
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                          Re: 1963 18hp Evinrude Fastwin - longshaft conversion water pump problems

                          Yes, there was some scoring on the inside of the hub...... But very, very minor...... I'm still hard-pressed to believe it was the impeller. I think the key itself was maybe too short ( key was Sierra too)

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