Positive Crankcase Ventilation: Description and Operation

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.