CARBURETED Models

When engine is running at idle, high intake manifold vacuum pulls blow-by gases out of crankcase through PCV valve and into intake manifold where they mix with incoming air/fuel mixture. Fresh air enters crankcase from hose to valve cover.

When engine is running at wide open throttle, manifold vacuum at PCV valve decreases and vacuum in air cleaner increases. As a result a small amount of blow-by gas flows out of the crankcase and into air cleaner.

Fig 1: Crankcase Ventilation System (Accord & Prelude - Carbureted)

Fig 2: Crankcase Ventilation System (Accord & Prelude - Fuel Injected)

Fig 3: Crankcase Ventilation System (Civic - Fuel Injected)

Fig 4: Crankcase Ventilation System (Civic - Carbureted)