Winterizing Yanmar 2QM15

[Dalliance]

There are two drain valves on the 2QM15 that you can use if you still have raw water cooling. The one on the port side works well but the one on the starboard side is sticky and fragile. If the starboard side fails to drain after opening push an object up into it to displace debris lodged there. If it will not open then unscrew it from the casting to drain.

Interesting suggestion about the drain valves. I would never try to winterize my engine by just draining it and I don’t think you meant to suggest that. Too much chance of not getting it drained completely and you want the sure protection of the propylene glycol antifreeze and it’s corrosion inhibitors throughout the cooling system. The drain valves do, however, provide a way to confirm that the antifreeze went everywhere it‘s intended to go without it bypassing directly to the exhaust.
I always run my antifreeze (2 gal -100°F propylene glycol) through immediately on arrival at my haulout marina. The engine has been running for five hours or longer at that point, so I know it’s hot. If I ever break that routine for some reason and have to winterize later from a cold start, I’ll keep those drain valves in mind as a way to verify that the engine was up to proper temperature.

 

[RoyS]

Not seeing the drain valves in the service or parts manual diagrams. Any help locating it would be appreciated.

They are both shown on the drawing 8-1 above. Look at the mixing elbow, they are shown on either side of that on the drawing. They each come with a short plastic hose that aims down at the bilge, but the hoses are usually are lost over time.