i didn't take the engine out of the pan, so no gasket needed there. the thermostat was pretty cruddy. cleaned it up and put it in a pan of water and turned up the heat. no movement. will pick 1 up when i get the head gasket. still trying to get the broken bolts out. they are being stubborn.
other than the molded-in pipe on the outside of the head, there doesn't seem to be any other passages for the water passing thru the thermostat to travel in. it looks like the head shares the same water around the cylinders. using the parts manual...
http://www.tohatsu-nissan-parts.com...s Catalog M8B-9.8B (2011) - (00221030-7).pdf
gives only a few clues to the actual water flow. the 2 gaskets that sandwich the lower cowl (some call it the pan, fig.11) show water port openings. in fig 7 we see gasket #3. i see 4 water associated holes. one for the feed from the pump, one for the cooling water check port (small hole next to the dowel pin #4, pee stream), one for the idle port and the last i can't really say how it is fed or know how to call it, but believe it is the path of the heated or excess water to exit through the leg to prop. in fig 1 we see the 2nd gasket, #35. this gasket has 2 water ports that i can explain. the feed water from pump and the idle port. the larger openings to the side and aft of the exhaust pipe opening could allow the water feed to simply go across from the feed to be dumped into the port to the leg. without seeing that side of the case, i can only guess.
so, from what i see with the head off and the pics in the parts manual, i have to come to the conclusion the water that passes through the thermostat never sees the prop by way of the leg.
having said all that, looking closely at the drive shaft housing #1 in fig.7, the idle port and the (for a lack of a better word) leg port may not be separated totally. if so, this could allow a small amount from the main feed to exit the idle port, thus altering my statements above to some degree.
again i say, it would be nice to have a water flow chart of this engine.
tom