1981 360 ec water in engine

[Kgriggs33]

This weekend I noticed my heat exchanger had a hole and my starboard engine was three gallons low on coolant. It is a 454 Merc 340 thunderbolt. Engine runs fine but I decided to check the oil and it had about two quarts of water in the engine. I'm guessing the thing got hot and burned a head gasket. I'm going to do compression test this weekend. Any advice, tips, ect.

 

[Thornton69]

Take a close look at the plugs and while compression testing. Could be something a bit more simple like an intake manifold or gasket. May want to try pressurizing cooling system with plugs out to see if it is coming from a particular hole or going direct to crankcase.