i have an older mercuriser not sure of the year. had to change out the water impeller due to overheating not sure how many times it was over heated was bought from someone who didn't know much about the boat the boat will run great on muffs but as soon as it hits the water it backfires out of the carb(carb was rebulit) and no power tried playing with the fuel/air mixture screws but no change at all, can it be from the headgastet from it being overheated??? a noticed a bit of water in the oil. is there any way to check to see if air is getting in threw the headgasket without taking it apart??? any help will be great
