Pat mccarthy A friend of mine has a boat(NOT CAR QUESTION) for some reason he winds up with water in the engine. It has hydro locked several times he has to pull the plugs crank it over put the plugs back in and go again. He has even busted staerter bolts off trying to start it. Last winter he had water in the cylinders when he winterized ity There are no cracks in the heads intake or exhaust manifolds. It dosn't do it all the time. I am not a boat guy so haven't a clue how to stop the water from being sucked back into the engine.