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I agree with JimsCAL. The 5411 (and the M15) is unique in that it is directly raw water cooled without a heat exchanger and only one water pump.
According to the manual, water circulates thru the block and heads out to the exhaust manifold to cool down the exhaust ports and then thru the thermostat, if its open, and onto the exhaust mixing elbow, to the muffler and out the transom. If the thermostat is not open or only partially open, then most of the circulated hot water goes back to the mixing tee where it is supposed to mix with fresh cold water and then go thru the pump again for another cycle. Is this correct?
I also noticed that as the engine warms up more water comes out with the exhaust gases via the open or partially open thermostat, but at the same time the raw water pump starts getting hot as apparently it begins to circulate some of the hot water! This confuses me as I thought the hot water coming back to the tee should then mix with fresh cold water to cool it down before it is sucked thru the pump for the next go around so that the pump does not get too hot. But in my set up, the pump gets too hot to touch as the engine reaches operating temperature! Is this normal? I am concerned that the water pump may not be designed to pump hot water so this could be a time bomb? Anyone could kindly shed more light here or please correct my dumb notions?