Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Positive Crankcase Ventilation: Description and Operation


In order to prevent blow-by gases from reaching the atmosphere, a slight vacuum is maintained in the crankcase. This is achieved by connecting the crankcase breather housing to the air intake system between the throttle housing and air flow meter, where a vacuum is maintained under all driving conditions.

Fig. 11 PCV System:





In order to prevent blow-by gases from entering the atmosphere, a slight vacuum is maintained in the crankcase and camshaft area at all times. This is achieved by connecting the crankcase breather housing to the part throttle control orifice and the engine air intake elbow, Fig. 11.
To prevent the icing up of the control orifice during cold weather, the orifice is heated by a water heated housing and a breather heater element located in the oil filler tube to air intake elbow hose. This heater element is controlled by a relay, which is controlled by the power wash jet heater sensor.