Houseboat Holding Tank Vent

Discussion in 'Boat Design' started by ChuckP, Jun 23, 2020.

  1. ChuckP
    Joined: Jun 2020
    Posts: 4
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    Location: Waterloo, IL

    ChuckP New Member

    It appears the vent line from the holding tank on our 1995 Gibson Houseboat is clogged and I thought there might be a screen in the line near where the vent port is located on the exterior of the boat. I attempted to knock the screen out with a screw driver (I figured the screen could only lead to blockages) . Instead of a screen, however, there appears to be a plastic cap of some kind blocking the tube....unless the line is making a 90 degree turn and i am hitting the back of the elbow. Any suggestions?
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to you

    Pictures would be welcome as well.

    Highly probable that it is an elbow.

    It will take some doing but can in interior be sufficiently removed for access?

    Vents are often easier to change than clean.
  3. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Invest in a borescope for your phone, it's cheap. Then you can actually see what's going on.
  4. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . . .


    Welcome to the forum.

    What makes you believe the vent is clogged?
    You don't know for certain that it's clogged?
    That may be a good place to start, determine whether it's clogged or not.
  5. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    And don't remove the screen. It's there for two reasons. Holding tanks develop gas which just happens to be flammable. The screen is a flame arrester. Keeps the gas from being ignited. And it keeps the bugs out.
  6. ChuckP
    Joined: Jun 2020
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    Location: Waterloo, IL

    ChuckP New Member

    Thanks for the reply. I was able to find an interior access panel over the weekend. And, there is an elbow. I removed the end of the vent hose that goes into the tank which took a couple of hours, but ran out of time to try to remove the end with the elbow that vents to the outside of the boat. I snaked it from the waste tank end of the hose and there does appear to be stuff in it, but I can't get it to go all the way thru so I'll have to get the exterior side off this weekend and try again.
  7. ChuckP
    Joined: Jun 2020
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    Location: Waterloo, IL

    ChuckP New Member

    I believe it is clogged because after a good flush, I hear a loud bang or pop from the aluminum waste tank. Then there will be brownish water in the bilge area where some of the waste lines run. The noise is like there is pressure building up in the tank due to the flushing with no way for the pressure to be relieved until it finally 'explodes' some of the waste out around some of the fittings and hose clamps and then the tank pops as the pressure is released causing the tank walls to flex back in. Its smelly. All the hose clamps are tight, so another part of the mystery is where the yuck is coming from after the aluminum tank pops.
  8. ChuckP
    Joined: Jun 2020
    Posts: 4
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    Location: Waterloo, IL

    ChuckP New Member

    Good suggestion. I'll do it. Thanks.

  9. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    This is off the cuff, but what about a shot of air or a plunger push on the vent? Just a thought. I'd try it, but I'd also stop ising the system. Pump it out. And flush and pump it again, maybe a couple times. Then the air shot down the vent. Use a porta potty for awhile until resolved. If the air/plunger doesn't work; you might consider running some water back into the vent line, letting it sit overnite and plunging or air shot or maybe it'll break the clog....
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