Positive Crankcase Ventilation (PCV) System: Description

The Positive Crankcase Ventilation (PCV) system is designed to prevent blow-by gas from escaping to the atmosphere. The PCV valve contains a spring-loaded plunger. When the engine starts, the plunger in the PCV valve is lifted in proportion to intake manifold vacuum and the blow-by gas is drawn directly into the intake manifold.

Fig 1: Positive Crankcase Ventilation (PCV) System - System Diagram

Courtesy of AMERICAN HONDA MOTOR CO., INC.