Exhaust loop Anti syphon valve

[Henry Demolina]

The anti syphon valve on my 40.5 broke off at the stem. Looking at the valve, it appears to be a very flimsy setup and it's not surprising it broke off at the stem with all the heat and vibration.Has anyone replaced the original valve with a different brand such as the one made by Vetus?Are there some other more sturdy valves that I can use?Thanks,Henry

 

[Dick Carey]

Anti-Syphon Valve Replacement

Henry,We have a 1990 Hunter 33.5 with a 18HP Yanmar Diesel. I,too, had the anti-syphon valve start to leak seawater only while the engine was running. After unmounting the vented loop (with all hoses still attached, could I see that the anti-syphon stem had cracked on the rear side. The mounting holds the whole assembly too tight against the bulkhead and causes excess side pressure on the anti-syphon valve.Mine was a plastic (Glass Filled Nylon??) valve assy made by Scot Marine in FL. I was able to buy a replacement for it at a chandlery in Newport, RI. It comes with thread reducer (that's the part that cracked) of the same plastic material. DO NOT use a brass thread reducer (which are available in the hardware store). Brass & Stailness (on the vented LOOP) will cause about a 0.2 Volt couple which will dezincify the brass when warm seawater (an electrolyte) flows thru it. Stay with plastic ( or stainless steel). When remounting the whole vented loop assembly to the bulkhead, I put about 6 stainless washers between that and the bulkhead to let it stand off the bulkhead and reduce side pressure on it. Good luck.Dick CareyS/V Puffin

 

[Henry Demolina]

Thanks

Dick, thanks for you response. It makes a lot of sense.Happy SailingHenry