Engine anti-siphon

[Kit Walther]

I have a 1981 Catalina 30 with a Universal (Kabota)11 hp diesel. I am concerned about the anti-siphon devise and would like to know what I need to do to make sure it is in good operating order. I believe it is located below the kitchen sink (a brass curved tube?). I was told these devises contain a float which can stick and allow water to siphon into the engine. Is this a fact? I would appreciate hearing from folks with some knowledge of this potential problem and your suggested maintenance solutions. My dielel has a freshwater cooling system with a heat exhanger that is cooled with outside water. Thanks.

 

[R. Hodge]

The purpose of the anti-siphon valve is to suck air after the engine is shut down, preventing a siphon action that can cause water to flow through the sea water intake, sea water pump, heat exchanger, through the muffler and then back into the engine through open exhaust valves. Problems can occur if the anti-siphon valve get's stuck closed. It's simple to check by just blowing into the opening on the top. You should be able to blow air from the outside in. If not, replace it.Hope that helps,Ron

 

[Tim D.]

Anti Siphon loop

I have an '84 30-T. The loop has a one way vent that will allow water to be 'pushed' out the exhaust. But when water is being siphoned back to the engine, the vent allows air in to break the siphoning.You can check the vent by shutting the engine off and then opening the cabinet under the sink and listening for water running back into the engine. You will be able to hear it if you are close to the vent.I discovered a bad vent when the engine would not turn over when I attempted to start it.. I thought it was a bad battery, bad starter, etc. Too much compression due to the water in the engine. Luckily, I am in fresh water on the Great Lakes. Could have been a zebra muscle or some other debris in the vent.Tim D.

 

[Chris Gonzales]

Close the intake valve

When the boat is under sail, sitting at anchor or in the slip it is best to close ALL seacocks. (I know, on our older C30's they are really "ball valves on pipes") This definitely includes the raw water engine intake valve. After we motor out of the slip, raise sail and kill the engine, we immediately close the valve. Opening it to restart the engine later is a habit for us. It is worth the little bit of extra effort just in case Mr. anti-siphon decides to sleep on the job.Chris