OK guys I need big help on this one. I have a 1973 johnson 50 hp model 50ESL73R. The engine is overheating. This is what happened, impellar was bad I changed it apparently the rubber grommet on the water supply tube didnt not make a seal and the motor severly and I mean severly overheated. It melted the plastic relief valve in the head and warped the thermostat. This is every thing I have done to rectify the problem but I am at a dead end. I fixed the tube, changed the thermostat twice, replaced the relief valve, replaced the water jacket gasket , replaced the head gasket and have had the head machined. I have visually checked for cracks in the head but have not dye penetrant tested it yet. When i run the motor it seems to have exhaust coming out of the water outlet (spurting water and feels like an air pressure coming out) still overheats. Is there a chance the engine is cracked somewhere internally by the exhaust port?? I am runnning about 110 PSi compression after the heads were redone 105 PSI beforethis is for both cylinders weather I leave the other spark plug in or out during the test it doesnt matter The motor seems to run good, could the top of the motor warpped?? I am out of thoughts....any ideas would help I even pulled out the thermostat and the relief valve and still the same thing, put the old headgasket back, in replaced the head bolts help I am at the end of my thoughts on where to go next
