Have a 1984 350/260 v8 merc, Alpha 1 , power steering, Twins, ..... A little history first, bought boat end of last season, starboard motor consistently ran just slightly hotter than the port, kept an eye on it, didn't think much of it nothing changed till this year, Just replaced impellers, bellows boots, water hoses on drives, ran motor on muffs water was pumping out everywhere except the prop just a tiny tiny stream. and motor immediately began to overheat. Unfortunately had to put boat in water so now somewhat limited to what I can fix. Last night changed thermostat, didn't work, I took the top of stat off and check it was open,, I felt the hoses to see any differences on the motors and the two smaller hoses that go from the top of the thermostat housing to the risers were extremely hot, compared to the cold ones on the good motor. I don't know how the cooling system really works on this likie what hoses are going where, what should be hot or cold or doing what....? My guess is to start taking things apart look for blockage, obstructions,,,, Water pump on motor??? can I test that? What's my next step???? Thanks in Advance..