### Positive Crankcase Ventilation (PCV) System

#### OPERATION

Exhaust blow-by gasses are routed from the crankcase to the intake manifold, where they are combined with the fuel/air mixture and burned during combustion. This reduces the amount of hydrocarbons emitted by the exhaust.

A PCV valve is used in the line to prevent the gases in the crankcase from being ignited in case of a backfire. The amount of blow-by gasses entering the mixture is also regulated by the PCV valve, which is spring loaded and has a variable orifice.

The important components of the PCV system are the following:

- PCV valve
- Valve cover
- Air intake chamber
- Ventilation case
- Hoses, connections and gaskets

  Fig. 1: The PCV valve functions differently according to the engine operating conditions

  Fig. 2: PCV system flow