The Positive Crankcase Ventilation (PCV) System vents harmful blow-by gases from the crankcase into the upper intake manifold, so that they can be burned along with the air/fuel mixture. The PCV valve limits the fresh air intake to suit engine demand and prevents combustion from backfiring into the crankcase.
The PCV valve is operated by engine vacuum. As the engine operates, blow-by gases are drawn into the intake manifold for burning. When the engine is at idle, the valve is fully open and a large amount of blow-by gases are burned. As the engine speed increases, the valve closes, allowing fewer blow-by gases to enter the intake manifold.
See Figure 1
- Remove the PCV valve from the valve cover grommet.
Shake the PCV valve.
- If the valve rattles when shaken, reinstall it and proceed to Step 3.
- If the valve does not rattle, it is sticking and must be replaced.
- Start the engine and allow it to reach normal operating temperature.
Check the PCV valve for vacuum by placing your finger over the end of the valve.
- If vacuum exists, proceed to Step 5.
- If vacuum does not exist, check for loose hose connections, vacuum leaks or blockage. Correct as necessary.
- Disconnect the fresh air intake hose from the air inlet tube (connects the air cleaner housing to the throttle body).
Place a stiff piece of paper over the hose end and wait one minute.
- If vacuum holds the paper in place, the system is OK; reconnect the hose.
- If the paper is not held in place, check for loose hose connections, vacuum leaks or blockage. Correct as necessary.
REMOVAL & INSTALLATION
For removal and installation of the PCV valve, refer to the procedure in General Information & Maintenance .