Positive Crankcase Ventilation: Description and Operation

The only flow through the oil/air separator is the combustion blow-by, as there is no fresh air inlet to the crankcase. The primary flow of blow-by into the separator is through a hose (item #171) from the timing chain housing. The oil/air separator causes oil, which may be suspended in the blow-by gases, to be separated and drain back to the crankcase through a hose (item #167) to the oil fill tube. This hose may also flow some of the blow-by gases into the separator under certain conditions. The upper smaller nipple connects through a hose (item #165) to manifold vacuum. This hose draws the gases from the separator under high manifold vacuum (idle or steady speed) conditions. There is a 1.52 mm (0.60") orifice inside the smaller nipple to restrict flow through the hose (item #165). The lower, larger nipple, connects through a hose (item #168), to a rubber connector (item #179) to a tube (item #2), to the air intake duct from the air cleaner. This hose draws gages from the separator primarily under high air flow (high rpm), low vacuum conditions.