Blowby in Crankcases

Crankcase blowby is the leakage of the combustion gases from the combustion chamber through the piston and the liner into the crankcase.  Crankcase blowby indicates a wear of the piston rings. 

The leakage of the exhaust gases can also occur at the turbocharger.  Crankcase pressure should be continually monitored.  Increase of crankcase pressure can lead to safety issues such as crankcase explosions