My motor blew a head gasket and was leaking water like an overdue pregnant woman, so I pulled the head off. It was running fine with just a little flutter at idle. No real issues other than losing a ton of water. When I pulled the head, the exhaust valve closest to the leak has a bright tan finish and the others are covered with just carbon. Would this be from water getting in the cylinder or maybe a vacuum leak or something? This thing doesn't get driven hard at all, so I'm more asking just from a maintenance standpoint. Thanks for any help in advance.