A conversation I had with J.D. at Downwind Marine
in San Diego
supports Pura Vida's opinion. He told me of a discussion he had with an employee of the valve manufacturer who had actually visited the factory in China
. The rep said that when they make low cost valves, anything that even looks remotely like bronze is thrown into the melting pot, thus putting the metallurgy of the finished product in question. He said that more expensive valves have better quality control, though.
In my initial post I mentioned that there was no electrical connection to the valve. Specifically, it was not connected with a ground wire to any other component on the boat. It's only connection to the generator was through a 3 foot length of rubber hose, a strainer, the cooling water pump, and another run of rubber hose. Thus I don't believe the corrosion
was caused by stray electrical current, especially since the generator has only about 230 hours on it. Now that we have a nice solar
array, we hardly run the generator at all.
Thanks to everyone who has contributed to this discussion. On my last trip to San Diego
I purchased Marelon replacements
to hopefully prevent this problem from recurring. I have also added "cycling hull valves" to my monthly maintenance
schedule, something I should have been doing but wasn't.