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.
PCV System: Operation
During idling and slow speed operation, crankcase gases are drawn into combustion chamber through a flame guard and PCV valve on 4-cylinder models or through an oil filter cap and PCV valves on 6-cylinder models.
During high speed or full throttle operation, crankcase gases are drawn through hose to intake manifold and excess gases are drawn through hose to air cleaner. On Turbo models, crankcase gases are drawn through hose to turbo-compressor intake.
On Turbo Diesel models the oil separator valve is connected to the intake side of the turbocharger. The valve is controlled by intake pressure. If intake pressure drops too low, the valve closes to prevent excessive oil consumption. SeeFigure .
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.