Answer: blowby

AnswerCrossword Clue
BLOWBYPass easily
BLOWBYAuto engine leakage
blowbyleakage of the air-fuel mixture or of combustion gases between a piston and the cylinder wall into the crankcase of an automobile
blowbyleakage of exhaust fumes
blowbydevice, fitted to a crankcase, for conducting such gases back to the cylinders for combustion