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Cooling Water Pump Replacement for Air Conditioners-gctid804514

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    Cooling Water Pump Replacement for Air Conditioners-gctid804514

    The cooling water pump for the air conditioners on my 3818 Motor Yacht stopped running. With power on, I can hear it humming, but it is not pumping. It is located below the sole in the master suite, under the bathtub. Any suggestions on how to remove and replace it? I don't see any way to gain access to it.

    #2
    Are you sure it is under the master suite ? Usually 38, at least the one of my buddy, has 2 a/c units with only one water cooling pump. The pump pick up is in the back of the boat, cools unit 1 and the main cabin then gets to unit 2 in the main stateroom, the exit is at the front of the boat. Also the pump is usually not too far from the strainer.

    On my boat, a 3988, the cooling pump is just beside to the rear of the port engine, I would guess it is around the same spot on a 3888.

    By the way, mine was burnt when I bought the boat, this pump is stupidly expensive.

    good luck
    Eric
    Bayliner 3988 1995 Hino 250hp

    Comment


      #3
      In my 3870, the water pump for the AC units is between the stringers in the well under the floor hatch at the entrance to the master suite. The thru hull for the AC is there, as is my macerator, and the front of the holding tank. I have a sump for the shower that I believe is under the tub and hard/impossible to access. . .

      just thoughts :whistle:
      . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

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        #4
        The thru-hull/seacock and strainer are directly under the sole hatch in the master stateroom doorway, near the black water tank. I followed the hose with my hand and it goes in to the centerline of the hull, to the pump which is mounted on a bulkhead opposite the blackwater tank wall. I was able to put a camera into the hole and got photos of it. Its a March pump, model AC-5C-MD. And you are right, its really expensive!

        I'm planning right now on abandoning it in place and installing a new pump with a priming reservoir under the stateroom bed, near the forward AC unit. Then, I'll have to re-plumb the supply hose to the aft AC which is at the helm station.

        Comment


          #5
          Yep different boat but it is the same pump.

          Got mine at Defender.com, it was the cheapest at that time (295$)

          March Pump AC 5C MD 115Volts

          Imagine the local Searay dealer in Canada wanted 950$ for that pump ...
          Eric
          Bayliner 3988 1995 Hino 250hp

          Comment


            #6
            "With power on, I can hear it humming, but it is not pumping."

            Your pump may be fine and just jammed.

            Most of the March pumps are magnetic drive - the pumps impeller is rotated by a magnetic coupling only, no direct connection.

            If/when crud, plastic bags, sea weed , barnacles, etc get into the pump cavity the impeller will decouple from the magnet and just sit there while the pump motor spins.

            Sounds much like what you have now.....

            Sometimes just running a heavy garden hose 'backwards' through the discharge hose of the pump will dislodge the mess bit often yo need to disassemble the impeller housing to remove the gunk.

            Hope this helps
            Northport NY

            Comment


              #7
              I have a 2002 3788 Bayliner Sedan bridge.....I had the same issue and found out that my strainer lost it's prime. The AC still ran for 2 minutes but quit pumping. Look under the quarter birth mattress...there is a panel that gives you access to the strainer and pump.

              Thanks

              Bob Mello

              Comment


                #8
                "Bob Mello" post=804581 wrote:
                I have a 2002 3788 Bayliner Sedan bridge.....I had the same issue and found out that my strainer lost it's prime. The AC still ran for 2 minutes but quit pumping. Look under the quarter birth mattress...there is a panel that gives you access to the strainer and pump.

                Thanks

                Bob Mello
                Good point, also note that the pump is NOT self priming:

                ``OPERATION:Pumps are not self-priming, lack a suction lift, and thus require a flooded suction. These pumps cannot be run dry because the impeller requires the liquid being pumped for lubrication. For liquids with a specific gravity greater than water, have a higher viscosity, or for elevated temperatures, a trimmed impeller may be necessary. For application assistance, contact March Pump.``

                http://www.defender.com/pdf/502649_M...ps Tech sheets
                Eric
                Bayliner 3988 1995 Hino 250hp

                Comment


                  #9
                  I tried to push water backwards through the pump with a garden hose, but was unsuccessful. I tried from each of the AC discharge thru-hull fittings and also disconnected the supply hose for the aft AC and tried from there. No water is getting through. I don't see any back flow valves in the lines, but acts like there are some. Pump still not working. As I said a little earlier, I am going to go ahead and install a new pump with a priming reservoir under the master stateroom bed.

                  Comment


                    #10
                    "I tried to push water backwards through the pump with a garden hose, but was unsuccessful."

                    I would check to make sure there is not something else wrong here as we have 'winterized' these systems each year for over 30 years by utilizing a wetvac to remove all water puling from the discharge side as well as the feed side - if a wetvac can pull the water out certainly a hose should be able to flow additional water.

                    What might be restricting your 'running' pump?

                    Hope this helps
                    Northport NY

                    Comment


                      #11
                      "aokaeding" post=806526 wrote:
                      I tried to push water backwards through the pump with a garden hose, but was unsuccessful. I tried from each of the AC discharge thru-hull fittings and also disconnected the supply hose for the aft AC and tried from there. No water is getting through. I don't see any back flow valves in the lines, but acts like there are some. Pump still not working. As I said a little earlier, I am going to go ahead and install a new pump with a priming reservoir under the master stateroom bed.
                      I don't think this is possible (to push water backward), pretty sure the a/c units prevent the water from going backwards, same goes for the pump.

                      To make a test I would close the seacock valve, disconnect the input to the pump, then re-open the seacock a few seconds and the water from under the boat should be entering the boat. That means no issues from the input side.

                      Reconnect everything dont't forget to close the seacock.

                      Next test is disconnect the the output of the pump (with the seacock closed). connect a water hose on it and water should be coming out of the outputs in the hulls. If successful that implies that the hose from the pump to the a/c units is good.

                      If the input and the output are good, pump is bad.

                      Always be careful when disconnecting seacocks, make sure you understand the risks.

                      Note: you may want to ask for a professional advice to reduce any risk of errors
                      Eric
                      Bayliner 3988 1995 Hino 250hp

                      Comment


                        #12
                        "I don't think this is possible (to push water backward), pretty sure the a/c units prevent the water from going backwards"

                        With the individual A/C cooling tubes I utilize a regular bilge pump to circulate "Rydlyme" thru the tubes every 7-8 seasons to get the buildup out of the tubes.

                        I have run into no restrictions in fluid flow on any of the units while doing this even with a 300 gph bilge pump.

                        "same goes for the pump"

                        Perhaps some of you have different March pumps than I have worked on with 4-5 Bayliners but the March pumps I am familiar with have 'paddle' wheels to drive the water flow and not the positive displacement flexible impellers that we are all more used to seeing. Due to this they are NOT self priming but they do flow some water even when they are static - not to mention they have magnetic couplers.

                        Have you had the pump housing itself apart yet to inspect it?
                        Northport NY

                        Comment


                          #13
                          Thanks everybody for your input. I have resolved the issue by replacing the pump. Everything works fine now.

                          For those interested, here is how I replaced the pump. As I mentioned earlier, the pump is screwed to a transverse bulkhead under the bathtub, an inaccessible location. I unblocked the black water tank and disconnected it, then slid it forward to get more room in front of the pump. Then I had my 10 year old great grandson crawl down through the access hole so he could get in front of the pump. He was able to remove the 4 mounting screws and get the pump loose (only his feet and lower legs were sticking up while he was working!). Then I could pull the pump out far enough to disconnect the hoses. I noticed that the outer jacket on the pump outlet hoses were dry rotted so I also replaced all of the hoses. The old hoses were automotive heater hoses. I replaced with marine rated water hoses. I bought two hanger bolts and had my g-grandson turn them into the upper mounting holes for the pump. This was so he could lift the pump into position and have the hanger bolts hold it up. He then replaced the lower two screws and put washers and nuts on the hanger bolts to complete the installation.

                          Hope this is useful to anyone else who has to replace this pump!

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