Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.