I may be buying a boat with a Force 50 hp motor. The guy tells me it blew a head gasket, he has a new one, but did not have time to put it in. He also said he changed the impeller last year. I don't know anything about boat motors so I'm asking here, What am I looking at as far as other possible damage associated with a blown head gasket? I'll be having a boat mechanic fix the gasket if I get it. Just looking for advice from you guy's. Thanks, Maxxie