Small Engines (Lawn Mowers, etc.): oil leak, cylinder bore, valve guides

Question
I have a Kohler TH-18S 54511 engine. It is leaking oit out the crankcase vent, why? What could be the cause?

Answer
Roger, this is a sign of an engine with excess "blow-by" If the engine is older, the rings and or valve guides can be worn. But FIRST , check if the oil fill tube and dipstick are TIGHT !!!! This will cause a loss of crankcase vacuum. If they are..... Suggest you take the head off and see how if the cylinder bore or guides are worn. If they are... it looks like a major overhaul is emminent. Let me know what happens