I'm sure someone knows exactly what I should do. Recently I acquired a 1986 Mercury 25HP S/N 0A97255. It looks to be in perfect condition, starts good and has good compression 120 PSI but, with muffs or in the tank no water comes out of the pee tube. Water pump is good, lots of water flows out the 2 holes under the cavitation plate and through the 6 exhaust holes. I cannot blow air through the pee tube nor from the copper water pump tube but, air flows freely from the top of copper tube even though tube is seated in the upper seal. locale marine parts man suggest removing cylinder cover and check for plugging and inspect the thermostat (I can't find the thermostat). Please give me some direction..... Thanks, Dennis