I always like to share things that I find in the field that I think are important to boat owners so they may see some of the tell-tale signs so they avoid costly repairs later down the line.
Below is a link and some photos of what happens when an exhaust manifold leaks sea water back into the cylinder via an open exhaust valve. This particular engine was a 2004 Volvo GXi-E six cylinder, 225 HP, gasoline inboard engine attached to a Volvo sterndrive. This was an actual inspection I conducted for a client last week. I took photos to document the findings.