I have a 1978 johnson 15hp. For a while it was only running on one cylinder, good spark and plug was wet ( thought it was gas but now I think it may have been water too ). Thought it was possible head gasket so I changed it and then cylinder started leaking at gasket on the out side of the head. Thought head may be worped so I bought new one and new gasket but still leaks at clinder head on the other side. All bolts were torqued. Other symptoms are exhaust coming out water discharge port, water coming out of shift rod gromet, only small amount of water out of weep hole ( exhaust relief). Compression 110 top cylinder and 90 on bottom bad cylinder, no leak down test. Can't really see a crack in cylinder wall and no scarring. Could the cylinder be cracked and pushing water into the cooling system causing presure to build up until it pushes through the head gasket and causing these other symptoms. Should I have the block cylinder head magniflexed at a machine shop or are there other test.