Crankcase Ventilation System Description: Operation

The primary control is through the crankcase ventilation housing which meters the flow at a rate depending on the manifold vacuum. In order to maintain the idle quality, the crankcase ventilation housing restricts the flow when the intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the engine air inlet to be consumed by normal combustion.