Impeller vanes...
I agree with Rich: on my Yanmar 2GM20F,it really doesn't matter which direction you align the vanes of newly installed impeller. As soon as the engine starts and the water pump turns, the blades will align themselves in the "right" direction automatically. Don Casey states it nicely in his tip sheet: "It doesn't really matter which way you bend the vanes; they will arrange themselves on the first revolution of the pump."
I agree with Rich: on my Yanmar 2GM20F,it really doesn't matter which direction you align the vanes of newly installed impeller. As soon as the engine starts and the water pump turns, the blades will align themselves in the "right" direction automatically. Don Casey states it nicely in his tip sheet: "It doesn't really matter which way you bend the vanes; they will arrange themselves on the first revolution of the pump."