The intake manifold vacuum removes the crankcase vapors and piston blowby from the engine. Emissions pass through the PCV valve into the intake manifold plenum. The vapors then become part of the calibrated air-fuel mixture, are burned and expelled with the exhaust gases. The air cleaner supplies additional air when the engine does not have enough vapor or blow-by gases.
REMOVAL & INSTALLATION
- Separate the PCV valve hose from the valve.
- Using the correct size socket or wrench, unscrew the PCV valve from the intake manifold.
- Inspect the valve for operation.
- Screw the new PCV valve into the intake manifold, and tighten until snug.
- Attach the PCV hose to the valve.
See Figures 1, 2, 3 and 4
To inspect the system unscrew the PCV valve from the intake manifold and shake it. If the valve rattles, this is a partial indication that it is okay; if there is no sound, it must be replaced and the PCV hose cleaned by spraying solvent (such as a carburetor cleaner type of solvent) through it.
If the valve rattles, you should still check the PCV valve with the engine idling. Pull it out of the vent module and place your finger or thumb over the end to stop air flow. You should feel some suction, and the engine speed should drop slightly. If there is no suction, or if the engine idle speeds up and smooths out considerably, replace the valve. Inspect the PCV hose and clean it by spraying solvent through it, if the inside is coated with gum and varnish.
Check the vacuum at the PCV inlet tube, as well. Disconnect this tube from the air cleaner and loosely hold a piece of paper over the tube. After about a minute, enough vacuum should build up to cause the paper to be sucked against the opening with a noticeable amount of force. This test proves whether or not the suction side of the system is clear.
Regardless of PCV valve or system performance, the valve itself should be replaced at specified intervals. At this time, you should inspect the hoses for clogging and spray a small amount of a safe cleaning solvent designed for this purpose through the hoses to remove any accumulated sludge or varnish.