The document discusses crankcase ventilation systems and positive crankcase ventilation (PCV). PCV was invented during World War II to allow tank engines to operate while preventing water from entering the crankcase. The PCV system reduces blow-by emissions from the engine by up to 20% of total hydrocarbons. It works by using a PCV valve and hose to siphon crankcase vapors directly into the intake manifold or throttle body.

1. CRANKCASE VENTILATION
SYSTEM
POSITIVE CRANKCASE VENTILATION
(PCV)

2. CRANKCASE VENTILATION 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.

3. POSITIVE CRANKCASE VENTILATION ( 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.

4. 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.

6. 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.