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Holding Tank Pump Out Question, 28'

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  • Holding Tank Pump Out Question, 28'

    Is there a secret that I don't understand to having my holding tank pumped out? Ive got a 28' LC. It has what looks to be the original system, including a macerator pump. I've tried to have the system pumped out and for some reason it wont empty and contents. Is there a valve somewhere that I am unaware of? The boat looks to have the original "Plastic" plate that has two openings. Any info would be terrific.
    Thank you,
    Wally (Ocean Fury)

  • #2
    Do you have a Y valve in the system? If by pumping out you mean via a vacuum pumping station then it is possible you are not getting the vacuum flow to the tank.
    "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it or repaired it. That's my job now that I'm retired.


    • #3
      If you have the same numatic recirculating head I do, you have to pull the silver lever at the bottom front of the toilet which opens the tank valve to the floor flange. Then the pump out will pull from the internal holding tank built into the head.
      Current Fleet - 1978 VIP w/4.3 V6 Merc (Glas-Hawk)
      1976 28ft w/twin Yanmars - Kaulquappe
      1980 181 Runabout w/470 Mercruiser

      Previous Affairs
      1977 17 w/115 Merc Tower of Power
      1980 2100SL w/470 Merc
      1977 2100SL w/470 Merc
      1979 18'6" "Donzi-Ply" w/470 Merc
      1980 8'6" Dinghy w/2 OP (oar power)
      2002 10ft w/15hp Mer 4 stroke


      • #4
        Wally I had that same pumpout plate, never did figure out what the smaller hole was for. Myself and others have removed the plastic plate and replaced it with a regular pumpout fitting on a starboard or stainless adapter plate. I have a wye valve under the kitchen sink but it may not be original-take a peek under there and make sure it's lined up right if you have one.

        What kind of head do you have?


        • #5
          Please provide a photo of your head (preferably nothing in the bowl...). I might be leaning to what Bill says, vacuum issue. Under the sink, make sure the macerator discharge valve is closed, other wise you will not be developing the vacuum needed. We have had no issues with our old one or our new one pumping out. Once we pump it out, we run fresh water down the same hole we use the pump out on, fill the tank (two person job, making sure the toilet doesn't over flow obviously) and pump out again, we may do this two or three times to remove everything and as not to develop issue's in the future with odors. Winter time, we run some non-alcohol RV anti-freeze down there and through the system.


          • #6
            Thank you for your input on this!


            • #7
              Question hanging in the air. Did you get your head pumped out?
              The cruise liner QE2 moves only six inches for each gallon of diesel fuel that it burns.

              1982 28' Long Cabin "Molly Brown" sweating through a long hot summer. Massive California forest fires fill our sky with smoke. SUP paddlers and kayakers transit the harbor with abandon, thinking they have the right of way over all boats.


              • #8
                Socal, Thanks for asking. Yes. After getting my big head (mine, not the boats) under the seat to look at the connection of the hose, I found out that the previous owner by-passed the "pump-out" fitting! Apparently he decided that it was just easier to pollute our waterways. The head connects to the holding tank, which has a macerator pump. I fixed it.