Originally Posted by jgeltz
I installed a Vetus valve from Defender along with some exhaust tubing and all is well.
I have what I have been told is a near perfect exhaust installation lacking only an exhaust outlet stopcock to avoid siphoning in the sea when on a heel. And yet I got water in my valve chambers several times this season, wasting lots of hours in oil changes, filter changes, kerosene flushes, backstrain from pumping and detective work. As I have closed loop cooling and a heat exchanger, it was either the raw water pump (nope, but I changed the gaskets and impeller while it was off, the heat exchanger or the oil cooler/transmission circuit. As there was no change in the level of the coolant, nor was there any sign of water in the tranny fluid, I decided to look elsewhere. Eventually I determined that the valve in my nice and high anti-syphon loop (a Scott's, I think) would intermittantly STICK in the upright position, which didn't allow the siphon to break, and did allow water to rush back into the exhaust, rather than down into the waterlift.
Goddamnit. A plunger and a spring worth pennies has cost been a few hundred in oil, filters and angst. The boat's new to me, but I had a somewhat similar issue when a waterlift muffler failed on my previous boat's Atomic 4. Drove me nuts. Then I got a Vetus waterlock, got it nice and low vis a vis the exhaust elbow (right at the waterline) and my oil ages to a nice browny black instead of a horrible gray milkshake.
Back on the new boat, I have been advised to try the Vetus, but I am leaning toward the more bulletproof method of running a plain hose straight up into the pilothouse or into the cockpit. You could even run it so it "peed" a bit off the side, providing evidence you've got flow when your exhaust itself is under the surface. Shut down, and the air is always there and you hear the British toilet-type gurgling of water going into the lift, not into your diesel.