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Thread: Old Bilge Pump Question

  1. #1
    Join Date
    Aug 2009
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    Olympia, WA, USA
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    Default Old Bilge Pump Question

    On the underside of the lower casting of Bucephalus's old Wilcox-Crittenden bilge pump --a big bulkhead-mounted 2-5/8"D piston job-- is a small (~1/4") threaded plug. It looks like this:



    If I had to guess, I would say that it's a drain plug, but that seems peculiar to me, since any residual water in the piston simply drains back into the bilge. Frankly, I'm a bit embarrassed that I don't really know why this plug is there, and my ignorance is beginning to bug me.

    Does anyone have a definitive answer for what purpose this plug serves?

    Alex

  2. #2
    Join Date
    Apr 2005
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    Hills of Vermont, USA
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    Default Re: Old Bilge Pump Question

    I would certainly agree it's a drain plug - though it'll leave some water in. Maybe it's to drain the pump enough to service it?
    "If it ain't broke, you're not trying." - Red Green

  3. #3
    Join Date
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    N.E. Connecticut.
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    Default Re: Old Bilge Pump Question

    Yes, a drain plug. For those of us farther north it is a good way to drain the water to prevent freezing and splitting the brass tube.

  4. #4
    Join Date
    Jan 2008
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    Lake Champlain, Vermont
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    Default Re: Old Bilge Pump Question

    Quote Originally Posted by Garret View Post
    I would certainly agree it's a drain plug - though it'll leave some water in. Maybe it's to drain the pump enough to service it?
    Or to keep it from freezing in storage... ?

  5. #5
    Join Date
    Apr 1999
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    Hyannis, MA, USA
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    Default Re: Old Bilge Pump Question

    Absolutely to drain for winter when the boat's on the hard. Without it, water is left under the piston. It does not all drain back to the bilge.

  6. #6
    Join Date
    Aug 2009
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    Default Re: Old Bilge Pump Question

    Well, thank you all. I feel a little less dense having guessed correctly at its role.

    I worked on the pump a little bit today --specifically, I chucked the bottom casting in the lathe and polished the seat for the check-valve. The check-valve consists of a tapered brass plug in a tapered brass seat (at least I suspect the castings are brass rather than bronze), and the seat had, over its many years, somehow become properly chewed up.

    Which explains why I couldn't see the need for a drain plug: the seat was so rough that the cylinder drained adequately through the crummy seal. A little too adequately, in fact. I only thought to clean up the seat because I was losing so much of the water back through the valve between strokes of the pump in ordinary useage.

    So with the seat and valve both polished, and perhaps a little bit of grease to assist the seal, hopefully the pump's efficiency will be returned to where any doofus --even me-- will immediately understand the need for a drain plug.

    Again, thank you all.

    Alex

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