I have a sears craftsman mower 17hp and all of a sudden this started happening to mine. I pulled the air filter off and ran the machine and the oil starts off slow flowing from the breather tube into the air filter box, then it starts flowing like the Nile. Tons of white smoke and starts to shudder and dies. I thought it had to be a head gasket as it ran fine when I parked it 3 weeks ago. I pulled the head and the gasket is fine. so now I think I should have checked the carb first.. anyone have a different idea ?