Positive Crankcase Ventilation (PCV) and Oil Separators

PCV

The internal combustion engine will build pressure in the crankcase. When the engine is in the compression and power stroke a small amount of gas gets past the piston rings. This is commonly referred to as blow-by. This blow-by gas is a mixture of hydrocarbons and exhaust gasses. It is the job of the PVC valve to vent these gasses to the engine intake, so they are burnt and not released to the atmosphere. As the internal combustion engine evolved to CRD and GDI, compressions and engine temperatures increased. With high oil temperatures combined with higher engine revolutions oil mist became a problem.

Oil Separators

We have all seen white smoke coming from car exhausts. This is often the result of the PCV valve staying open and oil vapour entering the inlet manifold. To solve the oil mist problems oil separators are now fitted to many vehicles. Before the gasses are returned to the inlet it is channeled thru a series of baffles or filters slowing the speed of the gas and allowing the oil mist to condense. The oil droplets are then returned to the crankcase. This stops the oil from entering the intake and thereby reducing carbon deposits in the inlet system. The OSV is normally integrated or mounted on the rocker cover.

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OIL SEPARATOR VALVE | OSV-003