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Alpha 1 Gen 2 has my prop spun and why doesnt my new one fit?-gctid356661

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    Alpha 1 Gen 2 has my prop spun and why doesnt my new one fit?-gctid356661

    Hello all, pulled my boat out early last season as I assumed I had spun my prop, reving out at any increase in throttle, like a clutch slipping. Now that I have removed the prop it looks indentical to the new one with no sign of slippage on the nylon insert. When I fit the new Mercury prop which has the same serial number it seems to fit on the shaft a fraction too much towards the drive which results in it rubbing off the housing of the drive beyond the thrust washer.

    Any ideas guys, has my prop been spun and if not what caused this "slipping clutch " type of event.

    Thanks

    Mike

    #2
    There is a brass thrust washer that goes between the prop and the drive housing.

    Look at the old prop some times they stick to the prop or maybe it fell off and you didn't notice. That is usually why the prop and the housing rub.

    As for the slipping if its not the prop hub it could be the engine to drive coupler. Let's hope.its the prop as the coupler requires the engine to be removed to replace it.
    1989 Avanti 3450 Sunbridge
    twin 454's
    MV Mar-Y-Sol
    1979 Bayliner Conquest 3150 hardtop ocean express.
    Twin chevy 350's inboard
    Ben- Jamin
    spokane Washington

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      #3
      Thanks David, still have the old thrust washer and got a new one with the new prop, tried swapping washers, props etc with the same result, looks like the new one is a mm or so too deep. I presume if it were the prop spun it would be evident in a visual inspection, it looks identical to the new one with no distortion visable. Must research that coupler.

      Mike

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        #4
        The hub was not set (pushed) far enough in. Take the prop back and get another.

        Vic

        Ft Myers
        Vic Stewart SN
        Past Commander
        Cape Fear Power Squadron
        Ft Myers Power Squadron
        1998 2859 7.4 L/B2
        Raw water cooled

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          #5
          Thanks Vic, anyway of confirming that its the coupler thats had it?

          Thanks

          Mike

          Comment


            #6
            mikesmerc wrote:
            Thanks Vic, anyway of confirming that its the coupler thats had it?

            Thanks

            Mike
            Prop shop. I had one spun and you could not see it.

            Put a mark on the hub and prop of new one before you install. I do that for future reference.

            Comment


              #7
              The only high maintenance accessory on a boat should come in a bikini!!

              That is awesome, just sayin!

              Comment


                #8
                The "old Style" hub is a rubber donut with a splined bushing in the center...The donut is larger than the space it fits so it becomes a simple high friction fit. And I agree with marking, but you'll know quickly if the prop has spun..the RPM's will go high and the boat goes slow...happens primarily when getting on plane when the boat speed is slow and the rpms are coming up. You'll feel it lag and then lurch with reulting rpm changes. But it can happen at cruise speeds too. The is no way to look at a hub and tell if it's spun...even a prop shop won't tell you if it's spun..torque meterorama or not.

                Be aware though, you can get it rehubbed,,,,but it's not as good as a factory job. Some prop shops have 'old' hubs that really need to be tossed away. and when rehubbing an aluminum prop...the center might break.

                New style hubs are neat, practical and best of all can be changed with a small hammer. Go with the new...

                And always carry a spare nut kit and a thrust washer.

                My .25 cents worth:arr

                Vic

                Ft Myers
                Vic Stewart SN
                Past Commander
                Cape Fear Power Squadron
                Ft Myers Power Squadron
                1998 2859 7.4 L/B2
                Raw water cooled

                Comment


                  #9
                  Thanks guys, the centre of the prop is made up of an 8 sided nylon insert by the looks of it. The boat is out of the water at the moment and i would like to be sure before a relaunch. Any way of testing the coupler out of the water?. I lost power last season, like a slipping clutch, would only take low rpm to limp home, was pretty sure that it was the prop.

                  Mike

                  Comment


                    #10
                    Ordered another new prop and all is well, first one cast incorrectly.

                    Thanks to all, now I hope it cures my reving out problem.

                    Mike

                    Comment


                      #11
                      When you get a chance can you confirm that the fix worked please. Good information for the future.
                      Terry (Retired Diving Instructor and Part Time IT Consultant)
                      1998 Bayliner 2452. 5.7l V8 - Edelbrock 1409 4bbl - Alpha1Gen2 - Solent UK.
                      MMSI 235061726

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                        #12
                        I spun the prop on my old alpha gen II and had same concern as you, visibly it looked fine but wouldn't get any speed regardless of rpm's. Replaced hub and prop and all was good. Kept old prop as spare and bought new hub, became my back up, did mine stuck in a mud flat I tried to power out of. They are fairly easy to spin, imo.

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                          #13
                          Better that the hub shears vice the alternative.....

                          Comment


                            #14
                            mikesmerc wrote:
                            Thanks guys, the centre of the prop is made up of an 8 sided nylon insert by the looks of it. The boat is out of the water at the moment and i would like to be sure before a relaunch. [SIZE]3 wrote:
                            [/SIZE]Any way of testing the coupler out of the water?. I lost power last season, like a slipping clutch, would only take low rpm to limp home, was pretty sure that it was the prop.

                            Mike
                            When a couple goes you can usually see aluminum shavings just under the out drive shaft looking down from either side of the engine in the bilge. The drive must come off and the engine out to replace the coupler. No short cuts on that job.

                            Ken
                            300SD all options sold.

                            Comment


                              #15
                              Sorry Terry with my extremely late reply, yes the new prop cured that problem.

                              Thanks to all

                              Rgds

                              Mike

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