I re-powered in my Catalina 1984 36. I also installed an Anti-Siphon loop that intercepts the raw water at the injection point just prior to the exhaust outlet. The loop extends above the water line.
I consider myself technically inclined however struggle with this, considering the impeller blocks the water flow between the intake and the engine I do not see how a siphon can start when the engine is shut down.
Ed
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Ed Dewsnap
Marion, MA
1984 Catalina
Protects against leakage past worn or damaged impeller fingers when the engine is not running and the seacock is open/
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Nick thanks for the reply, that makes perfect sense, When the engine shuts off what about the water that is in the siphon hose, should I be concerned with the water in that hose rolling back into the engine when it is shut down. Or is it that there is so little it will not affect the engine.
Ed Dewsnap
Marion, MA
1984 Catalina
Sometimes there is no water in the loop at all and air is sealing the vent. In a properly designed system, both ends of the loop are below the exhaust manifold so that any water in the tube drains into the muffler.
Nick Caballero
Retired C36/375IA Mk II Technical Editor