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    Genset update

    I'm getting closer to normal operation; still need a little help.
    The vessel was hauled out last Nov. and all thru hulls removed, bead blasted and re-installed. All sea-cocks were inspected and found to be in great shape with no obstructions.
    Today (boat back in water) I closed the genset sea-cock, removed the intake hose. Open the sea-cock and saw water flow out about 4-6 inches above the hose nipple. With sea-cock closed, I added dawn soap to the intake hose and inserted a garden hose in the intake hose and secured it with a hose clamp. I pressurized the hose and saw soap suds coming out of the exhaust port. No leaks appeared while the system was under pressure.
    I removed the garden hose, added soap to the intake hose and reattached the intake hose to the sea-cock. I started the genset but no water (or suds) came out of the exhaust port. I let the genset run for 30 seconds; no water. I removed the pump back plate and inspected the impeller- no damage.
    Now I'm lost. Any ideas?
    1997 Bayliner 3988

    #2
    It sounds like the water pump impeller isn’t turning. You may have to spin the engine while watching with the cover off to see if the impeller is turning or not. That would be my next move.
    P/C Pete
    Edmonds Yacht Club (Commodore 1993)
    1988 3818 "GLAUBEN
    Hino EH700 175 Onan MDKD Genset
    1980 Encounter Sunbridge "Misty Blue" (Sold)
    MMSI 367770440
    1972 Chevrolet Nova Frame off Resto-mod in the garage
    Boating on the Salish Sea since 1948

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      #3
      Could also be loose water pump belt when underload
      Mark
      USCG OUPV
      1990 4588
      Carlsbad, CA

      Comment


        #4
        3 guesses.
        i think someone mentioned this. the impeller may not be making contact with the impeller driver inside the pump. if it was the wrong impeller size from a thickness perspective, it would probably slip off the driver. by wrong thickness I mean it isn't thick enough. when impeller is mounted onto the driver, the coverplate should almost touch the other side of the impeller. (maybe a half mm clearance).

        if the pump's bearings were frozen, the belt could just slip/slide around the frozen pump pulley.

        the impeller driver inside the pump may be broken and there is nothing to move the impeller.
        Novurania 335DL. 30HP. WKRP in cincinnati. Previously: Bayliner 3818 in PNW.

        Comment


          #5
          You could remove the outlet hose on the raw water pump. If you start the generator and no water comes out you can shine a light down the outlet nipple and see if the impeller is moving. If water does come out you may have a clogged heat exchanger. Did the impeller fail earlier in the boats history?
          Gibraltar, Mi.
          1986- 3870- Hino 175's - Just purchased May ,2017
          34' Tollycraft- sold
          88 26' Shamrock/ Diesel
          14' Zodiac Bay Runner

          Comment


            #6
            As Sunbird suggested in an earlier post, the heat exchanger tubes may be clogged by bits of rubber from prior impeller failures. In any event, take the faceplate off the pump, and crank the engine to see if the impeller actually turns. I have had one impeller that looked ok, but the centre spindle had spun loose and was not turning the vanes. Next take the end cap off the heat exchanger to see if there are any rubber bits in the cavity and tube ends. A small mirror may help. You may need to have an end cap gasket ready, and indeed a replacement end cap. I've had several that have split. But don't overtighten the end cap. Good luck with it.

            Cheers
            John H
            Brisbane QLD Aust
            "Harbor-nating"

            2000 - 4788/Cummins 370's

            Comment


              #7
              I'm thinking that a clog from impeller shrapnel is unlikely. as i understand it, the OP connected a pressure water hose to the pump inlet, turned it on, and confirmed water going out the exhaust port. i thinking that the pump isn't working for some reason, such as a defective impeller or defective impeller connection.
              Novurania 335DL. 30HP. WKRP in cincinnati. Previously: Bayliner 3818 in PNW.

              Comment


                #8
                Genset repair update!
                I removed the strainer cover and inserted a 3/8 plastic tube taped to a garden hose; with a rag in a plastic bag to cover the strainer opening, I charged the hose and started the generator. While water was flowing out the exhaust, I pulled out the tube and shut the strainer. For the first time in months the genset was running on its own. After heating to operating temperature, I shut down the genset and restarted it. Please let there be flow - thank goodness. Since then the genset has been started, heated and shut down without incident.
                Many thanks to all for the ideas. Special thanks to The other Gary for the dish soap idea. The wife was spotting for water discharge but using the dish soap left no doubt.
                1997 Bayliner 3988

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