Additional info. Oftentimes blowby is caused by defective PCV (Positive Crankcase Ventilation) valve. Check the valve first before you decide to overhaul your engine. THis is the usual cause of blowby wherein blowby gases tend to find other outlets to escape the engine. For additional info on PCV visit this url:

http://www.autotune.com/cprotest/cpc8c.html