Engine anti-sython

Discussion in 'Propulsion' started by gypsywaters, Mar 3, 2013.

  1. gypsywaters
    Joined: Feb 2013
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    Location: Hope Island Queensland Australia

    gypsywaters New Member

    Hi from newbie,

    I a have a problem with leaking engine anti-sython valve, the original anti-sython valve leaked so I replaced with new, the new anti-sython also leaks, it leaks onto the fan belt and then gets sprayed around the engine making a mesh.

    In order to eliminate the problem I was thinking of 2 options, option 1 remove anti sython valve and run a vent direct to the outside of the hull, this would be about 1.5m above water line, option 2 remove vent and dischrge into a tundish and then run drain to the bilge.

    In both options I have no idea how much water will be discharged from the anti sython vent, is it a lot or only a dribble ? in option 1 I am concerned the discharge will stain the hull side, in option 2 will the dischagre be so much that the bilge pump is working all the time

    I should add its a motor boat not sail, when underway engine running all the time.

    Appreciate comments on above or any other suggestions
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I assume you are talking about the cooling water anti-siphon valve. You might have gotten a defective new valve. The warranty should cover it and the seller should give you a new one. The other option is to run a hose straight up from a T fitting where the valve is. The hose has to be tall enough to create head pressure to prevent the water from squirting out.
     
  3. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

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    Those anti siphon valves are monsters that never work correctly. Direct vent over the side is the way to go. Dont make your vent too small or it will get clogged with salty crud and stop working .

    My vents are 12mm . The welded aluminum nipple to PPP plastic pipe is the siphon break vent in the picture


    Cockpit or other deck drains are a good place to vent the sea water. Dont use cockpit drains if there is a chance that exhaust could pollute a cabin or wheelhouse.
     
  4. gypsywaters
    Joined: Feb 2013
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    Location: Hope Island Queensland Australia

    gypsywaters New Member

    Yes cooling water anti siphon, if I run to cockpit drain how much water will dischagre ?
    The other option as gonzo suggests is to run hose up and out onto the roof, this would be about 2.2 meters above T fitting, would this be high enough to overcome head pressure and prevent water squirting out.
     
  5. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    How much ? A steady stream of half inch !!


    I dont know the flow rate, but I can hear the waterfall tinkle of water. Its a good audible indicator . If my sea chest picks up jellyfish or a plastic bag and restricts cooling water flow ... I hear it via the cockpit vent.

    Swan yachts use a small pee hole over the side like an outboard motor. It works, but makes a mess of your topsides after a while.
     
  6. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Only a tiny vent hole is required , but beware it might plug up fairly easily.

    Consider running the vent to the galley sink, seeing the flow will show all is OK.

    If the water is warm enough it might be used to wash/rinse dishes.
     
  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The valve usually goes on the feed side of the engine, so it is cold.
     
  8. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Careful when venting inside, you could kill yourself. I believe it is also against classification rules.

    On my installation, exhaust fumes backup and blow back threw the vent tube when the exhaust outlet is submerged, back pressured, in heavy weather .

    Manytimes enough vapours blows back threw the vent that exhaust stains the cockpit drain area.
     
  9. gypsywaters
    Joined: Feb 2013
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    Location: Hope Island Queensland Australia

    gypsywaters New Member

    Thanks for comments, i think i will run a vent to the outside, it will be usefull as a tell tail like an outboard as suggested above. From previous threads it seems anti siphon valves are commanly a problem and it avoids the possability of the vale not working correctly.
     

  10. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    Just a tell tale on a loop, works wonders, does not ever block up, and certainly vents the siphon
     
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