GASOLINE MODELS
Crankcase ventilation system is designed to direct blow-by gases into intake manifold to be burned by engine. System is a closed type and consists of positive crankcase ventilation (PCV) valve and connecting hoses. System supplies fresh air to crankcase through air cleaner.
Under normal driving conditions, fresh air is mixed with blow-by gases (inside crankcase) and flow through PCV valve into intake manifold. Under heavy acceleration or high-speed driving, intake manifold vacuum decreases and blow-by gases exceed PCV valve capacity. Gases are then routed through breather hose into air cleaner and carburetor to be burned by the engine.
Crankcase Ventilation System (1.4L & 1.6L Gasoline Engines Shown). Scheme 2
DIESEL MODELS
Diesel engines also use a closed crankcase ventilation system. System components include breather hose, valve cover outlet and inlet pipe. Crankcase blow-by gases flow out of valve cover breather hose and into air intake hose.
Crankcase Ventilation System (Diesel Engine). Scheme 3
MAINTENANCE
Check and clean entire crankcase ventilation system every 5 years/50,000 miles.
SYSTEM TESTING
On gasoline engines with engine idling, remove PCV valve from valve cover and place finger over valve inlet. A strong vacuum should be felt. Turn ignition key off and remove PCV valve from valve cover. Blow into threaded end of PCV valve. If air will not flow, remove PCV and hose and clean with appropriate solvent to remove obstruction. Retest after cleaning.
On turbocharged gasoline engines check oil separator and oil return pipe for clogging and leaks.
On diesel engines check breather hose and valve cover inlet and outlet pipes for clogging and leaks.