The smaller Yanmar engines are probably one of the most popular engines for small sailing vessels and runabouts, and with good reason. The engines are reliable, robust, pretty compact and spares are readily available. However, one of the items that often gets overlooked come service time is the raw water pump impeller, mostly because it is so hard to get at. The easiest way to service the pump is to actually unbolt the pump from the engine which although not as hard as it sounds it is still a pain. (For reference the water pump is behind the small pully at bottom left)
But the newer small Yanmar engines have been redesigned and now have the pump in a much more accessible place as the shot below shows. The pump is now essentially reversed and the access to the impeller cover is simpler with in most cases no need to remove the pump at all. This makes the world of difference as the pump is much less likely to get forgotten, the brass plate glinting at you, a constant reminder. The shot below shows the 3 cylinder engine that was being installed into a Hampton at Yankee Marina which incidentally replaced an older Yanmar that had simply worn out.
Incidentally, a full tutorial on changing a water pump impeller can be found here.
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