I had this happen a few years ago that did crack the block. I Tig welded the crack and reinstalled the cover plate as attached shows. Torqued to spec and used blue loctite.Beware of these engines, especially used. Kohler only showed they had the "courage" to build them to self-destruct.
Valve cover leaks.
The top cover bolts under the flywheel fan shroud loosen at under 100 hours on average. Some break off while other will contact the flywheel bottom side while running.
And the "final nail in the coffin" is the engine block will stress crack on the top right and leak oil constantly.