Cooling system: a leaking anti-siphon valve and a missing strainer

Unexpectedly @AlexMemfis suggested looking into the cooling system. He asked me to film the entire water route, from the inlet seacock to the outlet. Once I’d done it, he thought for about 15 minutes, then called with his observations.

The inlet valve is on the bottom of the boat, just behind the engine. A hose runs from it to the impeller. Water then goes to the siphon breaker above the waterline, which prevents reverse flow from the engine. From there, it enters the internal cooling circuit, mixes with exhaust gases, and passes through a hose into the waterlock/silencer — the green box in the video. Then it runs into the locker, up through a gooseneck bend, and overboard. The gooseneck prevents water entering backwards through the outlet when the boat heels or meets waves. The waterlock also has a second outlet for draining. The engine itself has an expansion tank containing antifreeze.

The inspection revealed two problems:
– water seeped from the anti-siphon valve while the engine ran
– no raw-water strainer to keep weed and other debris out of the system

I removed and cleaned the anti-siphon valve, refitted it, and adjusted its cap. I don’t know which bit helped, but the leak stopped.

I ordered a raw-water strainer on Amazon for €20.34. Fitting it was straightforward. After just a couple of outings, I found weed and a black piece of plastic inside. A satisfying result.

#maintenance