I have a 1965 aristo craft 17' fiberglass boat that has a mercruiser 110 i/o (chevy 4 cylinder basicly same as the nova 4 cylinder engine i was told) I bought this boat last year and quickly discovered that it would overheat at idle so I changed the impeller this year as well as replace the gas tank that had enormous amounts of rust in it and all hoses that come with the gas tank and performed a tuneup (there was no aperent signs of water in the oil and the antifreeze was still in the water lines when I changed the impeller)oil/filter/points/condensor/cap... Took it out on the lake this year and after about the fourth trip I went to take off from the dock and the motor stalled..... Not thinking it was any kind of oil problem I checked the electric system and found that the coil wasnt working great so I replaced that and still couldnt get the motor started after 2 days of this I decided to check everything when I pulled the dip stick it was full to the top with milk I drained the oil and added some more to be sure that the engine was not in hydrolock and it still turned over ok... we got it back home and removed the head and the head gasket is in good shape with no aperant leak by... I havent had the head checked for cracks yet but thinking back to last year I remember that there was a little water leaking out of the side of the manifold but wouldnt this cause a hydrolock if it was leaking by into the oil? and there was no visible water on the cilinders as well as carbon was still there good. I also checked the elbo on the back of the manifold and one side has carbon and the other looks like water has been there no visible cracks...what do I do next??? Im thinking have the head checked and than if it is ok get new gaskets and change the head gasked and the manifold gasket retourque and see what happens is my thinking good as long as the block isnt cracked because the engine never got warm???? Please help!!!! 