Background: New boat to me, motor yr is 1973. Recently replaced manifold and head gaskets due to water in oil. Upon start-up, pushed a freeze plug out and more water in oil. I'm thinking the increased compression from new head gasket coupled with the below diagnosis pushed it out and is forcing water into motor.
Diagnosis: it appears the existing gasket on the riser is not allowing water to pass through. Existing gasket is totally closed except for the middle exhaust hole (1 3/4" dia). I have the factory raw water system (open). Riser and manifold mating surfaces include the u-channel ports that are 180 deg offset from each other.
Question: is the gasket my problem? I'm showing the replacement gasket is basically closed also save for a 3/8" hole at the top. Any other ideas? Thank you. Gasket part no. 856028
Diagnosis: it appears the existing gasket on the riser is not allowing water to pass through. Existing gasket is totally closed except for the middle exhaust hole (1 3/4" dia). I have the factory raw water system (open). Riser and manifold mating surfaces include the u-channel ports that are 180 deg offset from each other.
Question: is the gasket my problem? I'm showing the replacement gasket is basically closed also save for a 3/8" hole at the top. Any other ideas? Thank you. Gasket part no. 856028