Damage to piston and cylinder head?
I'm rebuilding my dad's lawnmower engine (Kohler CV15S), because of a loud racket while starting/running. After getting the cylinder head off there was noticeable damage to the top of the piston and the head from a screw that somehow got inside.
Wanted to ask whether the piston and/or head need to be replaced entirely, or if I could just clean them up with a file.
Your thoughts?