Stus-List Check valve on bilge pump

David Knecht davidaknecht at
Fri May 22 09:12:31 EDT 2015

We had a discussion a few years back about whether or not to have a check valve on the bilge pump outlet hose and as a result, I removed the valve from mine.  All has been fine since.  Yesterday, while motoring for a long ways down the river, I noticed that the bilge was filling with water.  I pumped it out and the water immediately returned.  I pulled the pump out of the bilge, and water was pouring into the bilge through the pump.  When I lifted it, the flow stopped so it seemed to be siphoning/flowing through the bilge pump exit line, which is in the transom and when motoring, looks to be under water.  I have not checked yet to see if there is an anti-siphon loop.   I am guessing that this is one of the functions of the one way valve that was there before, but I can’t figure out why it never happened before.  The Whale 500 pump does not specifically say it has a check valve, but perhaps it does and it stopped working?  I had an oil spill into the bilge last winter and so maybe that is causing problems.  I plan to reinstall a check valve in the line so this does not happen again.  Any other thoughts?  Thanks- Dave

1990 C&C 34+
New London, CT

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