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Went to replace Alpha Waterpump and found Shaft Play

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  • Went to replace Alpha Waterpump and found Shaft Play

    I went to replace the water pump on my alpha today and found that with the water pump housing removed the radial play on the shaft was .052 inch (total back and forth)! This was measured on the main input shaft on the lower housing just above where the key way is in the shaft. This drive was operating fine, shifting fine, no water in oil! Clearly the bearing must be bad...correct??????Need advice!

  • #2
    ok I did a little homework. Sorry I got spooked when I saw so much endplay. The drive shaft for the lower unit has 2 bearings: one is a simple roller and the top bearing is a tapered roller. Shaft endplay is controlled by the tapered roller in one direction only. When the shaft is at rest it floats down away from the tapered bearing. I had a junk unit to compare to and there was no play in the shaft. Turns out the nut ( on the junk unit) on the gear end was lose which was pushing the shaft up into the the tapered bearing hence no shaft end play----April fools! Ok now here is a real question...my water pump lower housing has no o-ring on the bottom where it fits into the lower unit. Seems all the units at my dealer seem to be the o-ring type. I know at one point my low end was switched out. Do I have an early (or other) version low end and how do I specify this type water pump housing??

    Comment


    • #3
      Any unit that I have ever seen has had the O-ring groove in it. Could you give me the serial number of the unit, or the year and model?

      Tech Support
      Brunswick Corporation is the original equipment manufacturer (OEM). Sterndrive Engineering, Inc. (or SEI) is not affiliated with the Brunswick Corporation and is not authorized to sell or service Brunswick products.

      Comment


      • #4
        hmmmm, this is going to be a tough one! my upper unit is a 87 but the lower unit was changed out by a Marine Mechanic with a "used" unit. I dont know what vintage it is as the Mechanic originally told me he was just giving me a new (used) input shaft. He since moved to Florida............Where can I find a serial on the lower unit? I do remember a part number on the lower housing after I split the cases.

        Comment


        • #5
          The serial number is not on the lower as far as I know. Does it have a preload pin on the top of the driveshaft?

          Is it possible that the water pump did not come apart correctly. The base is actually two pieces glued together, and sometimes the lower piece stays stuck in the case.

          If you could email me a couple of pics, one of the unit, and one of the water pump base I could tell you more.

          Tech Support
          Brunswick Corporation is the original equipment manufacturer (OEM). Sterndrive Engineering, Inc. (or SEI) is not affiliated with the Brunswick Corporation and is not authorized to sell or service Brunswick products.

          Comment


          • #6
            There is no preload pin. I am sure of that. I am out of town at the moment and dont have the drive in front of me but when I poped the lower pump housing off there was a blue colored seal assembly below the cap. Not having played with that seal specifically it looked a bit unconventional to me. There were two small seal pieces (about 1 inch dia.) that fit into the bottom of the pump housing. However it looks like they also seal against the blue piece that stayed in the lower unit. It looked to me that the blue seal acted like a face seal with the smaller seal in the pump housing. This probably sounds a bit strange but one thing is clear. There will be no way to put a new style lower pump housing in without removing the existing "blue" seal.

            Comment


            • #7
              The blue piece is the bottom half of the water pump base. It came unglued. Remove that and install the normal water pump and you will be all set.

              Tech Support
              Brunswick Corporation is the original equipment manufacturer (OEM). Sterndrive Engineering, Inc. (or SEI) is not affiliated with the Brunswick Corporation and is not authorized to sell or service Brunswick products.

              Comment


              • #8
                Thanks for all your assistance! My "big picture" boating plan is to upgrade to twin small block chevys with alpha drives. My decision to do this is all based on SEI's part of providing "affordable" drive replacements.

                Regards,
                Kevin
                p.s. Does SEI plan to expand to other drives?

                Comment


                • #9
                  Problem Solved!

                  Just want to thank you guys for all your help this spring. Since you guys are so good with the drives can you help with the weather too? Since it is a rainy day I thought I would follow up on my on post. Well the problem is solved: To make a long story short my water pump was weak. It was weak because of a lower pump housing that had probably gotten too hot and warped slightly. (I suspect it has been this way since I bought my boat and my drive supposedly rebuilt!) With the bottom housing warped the wear plate was going to be warped too hence my water output from the pump was reduced. I went from 3.5 GPM and 14 PSI to 5 gpm and over 30 PSI output from the pump. After it became clear that the pump was capable of so much pressure the kinked hose issue goes away since there is plenty of pressure to overcome a kinked hose. Sorry to bore you with the details but I am a man of science. However I got the coolest risers in town now!

                  Comment


                  • #10
                    I can't help with the weather, other than to suggest wintering in Florida.

                    Glad everything worked out.

                    Tech Support
                    Brunswick Corporation is the original equipment manufacturer (OEM). Sterndrive Engineering, Inc. (or SEI) is not affiliated with the Brunswick Corporation and is not authorized to sell or service Brunswick products.

                    Comment

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