Hey guys just trying to get a little help here. This is my situation one day I went out in the driveway to pre-start my boat before taking it to the lake so I hooked it up to the hose just like I do for the past seven years and the boat wouldn't crank over all I heard was a grinding noise. So from the research I've done I took all the spark plugs out in a little bit a water came out of the far back left spark plug cylinder. So I immediately restarted the engine without the water source for about 30 seconds because I read that it would evaporate all the water that may be be in the cylinders. After that I let the engine go for a couple days I just left it in the driveway we never took it out or used it sense then. Needless to say when I tried to start it again the grinding noisehappened again. Took out all the spark plugs even more water than before came out of the same cylinder and some on the other side the adjacent cylinder as well. So I thought maybe a riser gasket was leaking so I took the risers off both sides manifolds off both sides in the manifolds had a considerable amount of water in them where only air should be . Change the oil which was not milky didn't seem like it had water mixed with it either. So I inspected and leak tested risers and manifolds which had no signs of rust and rebuilt both sides with new gaskets and now today I was trying to start my engine with a brand-new battery and starter and I have the grinding noise again. The engine will only spin over with all the spark plugs out. I even checked the spark plug gaps to make sure they're not hitting the piston tops but they seem fine. Guess my next step is compression test. Any suggestions would be fantastic. Thank you for reading.