CCV System
As stated above, 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 a grommet on top of the cylinder head cover at the dash panel end. The grommet contains a metered orifice of a calibrated size that meters the amount of crankcase vapors drawn out of the engine. A fresh air supply hose from the air cleaner is also connected to the front of the cylinder head cover on 4.0L engines and to the rear of the cover on 2.5L engines.
When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the metered orifice and into the intake manifold. The vapors are consumed during combustion.