I have a stock 2003 Mercruiser 496 HO with a bravo1 drive. It has the closed cooling system. The antifreeze level dropped and now it is in the crankcase with the oil. I attempted to refill the cooling system but the water ran quickly to the crankcase. I pumped out the crankcase and replaced the oil and filter. Then I pulled the plugs and added water again to the cooling system and rolled over the engine to see if water would shoot out the spark plug holes. No water shot out the spark plug holes. What can I do next to determine the issue. Is there something else besides the head gasket. that can cause this leak into the crakcase? What steps should I take next.

either a head gasket or cracked head or block....if you are in a real cold area and the antifreeze was not good enough may have cracked the block...

Ck the intake gaskets,the corner bolts loosen up and then it seeps into the lifter gally then into the oilpan,,dont start it,it wil wash the bearings out of it..

Also the intake manifold gasgets are molded plastic with o-rings molded into them,they crack and leak also..theirs a updated ones for the aueomotive division that are pure rubber with metal reinforcements,,,,,,way better and wont fail..