My 17 hp Kohler command blew the head gasket, was very hard to start for months, i guess it was leaking compression,and finally blew out and wouldn't start, new gasket in and it starts great, but engine locks up in a coupla minutes, good clean full of oil?, never burned any oil? lots of hours by last owner., its on a toro zero turn. plus I cleaned out a mouse nest in the shroud, cooling should be better? Coincidence? or am I missing something?