Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Positive Crankcase Ventilation: Testing and Inspection

Checking PCV Valve:






1. Warm engine to operating temperature and run at idle.
2. Disconnect PCV valve and ventilation hose from cylinder head cover.
3. Place a finger over valve opening. Check that vacuum is felt.
4. Remove valve and blow through from both directions. Verify that air flows through valve in one direction only (toward the intake manifold).
5. Replace valve if necessary.