Hello, I'm new to owning a riding mower but have worked on small engines for many years. Just picked up an old Snapper for a song, it looks like the head gasket was blown. The engine ran, but with great clouds of oil pouring out of the exhaust. I can see a dark mark under the gasket adjacent to the pushrod plenum. I'm thinking it's been leaking for awhile, but just recently started burning oil since the muffler was not dripping-full of it. Also, the dip stick showed a perfectly full crank...maybe TOO perfect...

I don't see any evidence of blow-by, so am I on the right track with this?

I don't see any evidence of blow-by, so am I on the right track with this?