Hunt\Fish guide
New member
I have a 225 EFI 3.0 Mercury that has one bad cylinder on the bottom left side on the passenger side of the boat. Not sure what the number is of that*cylinder. But it’s the bad one. How I found the bad cylinder. I pulled out the spark plugs on all the cylinders and found metal build up on the spark plug on that cylinder. So I pulled the heads off and on the bad cylinder there is a hole in that piston, about the size of a half dollar. The rod is bent and broke free from the piston. The piston is frozen at the top of that cylinder wall. What would cause this? What do I need to check and fix to prevent this from happening again after I rebuild the power head? Any ideas please help…