Small Engines (Lawn Mowers, etc.): Kohler motor, crankcase pressure, crankcase oil

Question
I have a Kohler CH20S motor on my mower. (Spec. 64541)  It is a twin cylinder with ohv.  It start ok and runs good without smoking or using oil.  I pulled off the oil fill cap while it was running and it has huge amounts air blowing out of the fill area.  I know on cars if this happens it is caused by blowby from cracked rings or worn cylinders.  I was told by someone that this is normal for this type of motor.  What can you tell me?

Answer
Hello John:

Your Friend is Correct. These Engines Use a Certain Amount of Blowby in the Crankcase. The Crankcase Breather/Vent Keeps the Crankcase Pressure at the Proper Level. If the Rings Crack/Stick/Break, then the Crankcase Breather/Vent Can Not Handle the Extra Pressure and the Crankcase Oil is Taken into the Carburetor and the Engine Smokes and Uses Oil. The Carburetor Throat and Sometimes the Air Filter will be Contaminated with Crankcase Oil. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model and Spec Numbers. Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John