k here it is bought a 1986 searay sundnacer week ago the guy started it run it i checked the oil looked fine took it straight to lake ran it for 30 minutes took it to slipwent back 2 days later would not staert after a lot of checking other things foundout motor was full of water engine was stuck brought it home yesterday pulled plugs drained oil sprayed pb blaster in all cyl put new oil in it i have it turning now good have felt all over exhaust manifold cant find any cracks visually the motor is a 350 small block merc if htese exhaust gaskets blow can it let water in oil? there was also water and oil in bilge area under motor the guy swears he had the boat on lake week befor no problems???? are the manifolds bad to crack internally? should i put plugs back in start and try to find leake or just take both manifold and risers off and have checked? thanks in advance for help