Crankcase Ventilation System Description. Saturn VUE

For 1990-2009 cars only

Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 Engine 🢒 Engine Mechanical - 3.5L (L66) 🢒 Crankcase Ventilation System Description

Crankcase Ventilation System Description

The compressed combustion gas which escapes past the piston rings into the crankcase is known as blow-by gas. Blow-by gas contains large amounts of carbon monoxide (CO) and hydrocarbon (HC). The positive crankcase ventilation (PCV) system prevents the blow-by gas from being emitted into the atmosphere. The PCV system routes the crankcase blow-by gas back into the intake system where the blow-by gas becomes part of the combustion process. The PCV system consists of the following components:

•	The PCV valve

•	The crankcase vent (breather) or air inlet tube

•	The air inlet filter or separator, if used

•	Any hoses or couplers

Operation


(1)	Intake Manifold
(2)	Low Pressure Chamber
(3)	Engine Blow-By Gases from Crankcase
(4)	Lower O-Ring, PCV Valve
(5)	Upper O-Ring, PCV Valve
(6)	PCV Valve
(7)	PCV Hose

The primary control of engine crankcase blow-by gas is the PCV valve. The PCV valve meters the flow of blow-by gas according to the manifold vacuum signal.

The section of the PCV valve that is below the lower O-ring is exposed to manifold vacuum, The section that is between the lower and upper O-rings is exposed to crankcase gases. The PCV valve allows some vacuum pressure to pass thru the valve internal orifice and create a low pressure condition in the crankcase. The blow-by gases in the crankcase are then drawn into the intake system and consumed in the normal combustion process. The volume of blow-by gas entering the intake manifold is precisely controlled In order to maintain idle quality. The correct PCV valve with the proper calibration must be used. The relationship between the flow of blow-by gas and the engine manifold vacuum is charted in the following table:

PCV Valve Operation

Manifold Vacuum	PCV Valve Opening	Blow-by Gas Flow
Low	Large	High
High	Small	Low

Results Of Incorrect Operation

A plugged valve or hose may cause any of the following conditions:

•	A rough engine idle

•	Engine stalling or low engine idle speed

•	High engine crankcase pressure

•	Engine oil leaks

•	Engine oil in the air cleaner

•	Oil sludge in the engine

•	Engine oil consumption

•	Excessive exhaust emissions

A leaking valve or hose may cause any of the following conditions:

•	A rough engine idle

•	Engine stalling

•	High engine idle speed

•	Incorrect engine crankcase pressure

•	Excessive exhaust emissions