Positive crankcase ventilation

CRANKCASE VENTILATION SYSTEM

POSITIVE CRANKCASE VENTILATION

(PCV)

CRANKCASE VENTIL ATION SYSTEM

A way for gases to escape in a controlled manner from crankcase

of an internal combustion engine.

Internal combustion inevitably involves a small but continual

amount of blow-by.

Occurs when some of the gases from the combustion leak past

the piston rings to end up inside the crankcase.

POS IT IVE CRANKCASE VENT IL AT ION (PCV)

During World War II, different type of crankcase ventilation be invented

to allow tank engines operate.

Normal draft tube ventilator allow water to enter the crankcase and

destroy the engine.

PCV reduces blow-by emissions from the engine.

20% of HC emissions produced by a vehicle.

The higher the mileage on engine and the greater the wear on the piston

and cylinders, the greater the blow-by into the crankcase.

MAJOR COMPONENT

The major component in PCV are PCV valve, a simple spring-

loaded valve with a sliding pintle inside.

The pintle is tapered like a bullet so it will increase or decrease

airflow depending on its position.

The movement of the pintle changes the orifice opening.

The PCV valve is located in a valve cover or the intake valley,

and fits into a rubber grommet.

HOW PCV WORKS

A hose connects the top of PCV valve to a vacuum port on

throttle body, carburetor or intake manifold.

This allows the vapors to be siphoned directly into engine w/o

gumming up throttle body or carburetor.

PCV has the same effect on the air/fuel mixture as a vacuum

leak.