Cherokee 4WD L6-4.0L VIN S (1998)
Positive Crankcase Ventilation: Description and Operation
Fig. 8 CCV System-Typical
CRANKCASE VENTILATION SYSTEM
These engines are equipped with a Crankcase Ventilation (CCV) system (Fig. 8). The CCV system performs the same function as a conventional
PCV system, but does not use a vacuum controlled valve.
A molded vacuum tube connects manifold vacuum to top of cylinder head (valve) cover at dash panel end. The vacuum fitting contains a fixed
orifice of a calibrated size. It meters the amount of crankcase vapors drawn out of the engine.
A fresh air supply hose from the air cleaner is connected to front of cylinder head cover.
When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through
the fixed orifice and into the intake manifold. The vapors are then consumed during combustion.