2 cylinder inboard yanmar engine

[ivanbranch]

Just gone to start my engine after the cold spell and have water spouting out of what looks like a by pass vent its a pipe coming off the top of the engine through this breather and back into the outlet that pushes the water back into the river....any ideas why this is happening???????

[haffiman37]

It is an 'anti siphone valve' and may prevent the water from filling the exhaust system and entering back into the engine when sailing.
Usually a rubber membrane inside that may have broken.
Not a typical Yanmar part, any valve from Volvo, Vetus etc may do.
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