See Figures 1 and 2
The Positive Crankcase Ventilation (PCV) system is used to control crankcase blow-by vapors. The gases are recycled in the following way:
As the engine is running, clean, filtered air is drawn through the air filter and into the crankcase. As the air passes through the crankcase, it picks up the combustion gases and carries them out of the crankcase, through the PCV valve, and into the induction system. As they enter the intake manifold, they are drawn into the combustion chamber where they are reburned.
The most critical component in the system is the PCV valve. This valve controls the amount of gases which are recycled into the combustion chamber. At low engine speeds, the valve is partially closed, limiting the flow of gases into the intake manifold. As engine speed increases, the valve opens to admit greater quantities of gases into the intake manifold. If the PCV valve becomes clogged, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase tube into the air cleaner to be consumed by normal combustion.
The Positive Crankcase Ventilation (PCV) system must be operating correctly to provide complete removal of the crankcase vapors. Fresh air is supplied to the crankcase from the air filter, mixed with the internal exhaust gases, passed through the PCV valve and into the intake manifold.
The PCV valve meters the flow at a rate depending upon the manifold vacuum. If the manifold vacuum is high, the PCV restricts the flow to the intake manifold. If abnormal operating conditions occur, excessive amounts of internal exhaust gases back flow through the crankcase vent tube into the air filter to be burned by normal combustion.
Incorrect operation of the PCV system can cause multiple driveability symptoms.
A plugged valve or hose may cause:
A leaking valve or hose would cause:
If the engine is exhibiting any of these conditions, a quick check of the PCV valve can be made. While the engine is idling, pull the PCV valve from the valve cover, place your thumb over the end of the PCV valve and check for vacuum. If no vacuum exists, check for a plugged PCV valve, manifold port, hoses or deteriorated hoses. Turn the engine OFF , remove the PCV valve and shake it. Listen for the rattle of the check needle inside the valve. If it does not rattle, replace the valve.
Never operate an engine without a PCV valve or a ventilation system, except as directed by testing procedures, for it can become damaged.PCV Valve
See Figure 3
- Remove the PCV valve from the intake manifold or valve cover.
- Run the engine at idle.
- Place your thumb over the end of the valve. Check for vacuum. If there is no vacuum at the valve, check for plugged valve or vacuum lines.
- Shut off the engine. Shake the valve and listen for the rattle. If valve doesn't rattle, replace it.
- Check the crankcase ventilation valve for correct application.
- Run engine until normal operating temperature is obtained.
- Block off crankcase ventilation system fresh air intake passage.
- Remove the engine oil dipstick and install a vacuum gage on the dipstick tube.
- Run the engine at 1500 rpm for 30 seconds, then read the vacuum gage while at 1500 rpm. If vacuum is present, the crankcase ventilation system is functioning properly. No vacuum indicates the engine may not be sealed and/or is drawing in outside air. Check valve cover and oil pan gaskets for leaks and repair, as required. If the vacuum gage registers a pressure or the vacuum gage is pushed out of the dipstick tube, check for the correct crankcase ventilation valve, a plugged hose or excessive engine blow-by.
REMOVAL & INSTALLATION
EXCEPT 3.8L ENGINE
See Figures 4, 5, 6 and 7
- Disconnect the negative battery cable.
- Disconnect the hose or pipe from the PCV valve.
- Gently pull the PCV valve out of the grommet in the valve cover or intake manifold.
- Installation is the reverse of removal.
See Figure 8
- Disconnect the negative battery cable.
- While holding down the PCV valve cover, unfasten the two cover retaining bolts.
- Remove the PCV valve cover, then remove the PCV valve, spring and O-ring.
- Inspect the PCV valve cover gasket for damage, and replace if necessary.
- Install the PCV valve, spring and O-ring.
- Position the PCV valve cover (use a new gasket, if necessary), then hand-start the retaining bolts.
- Tighten the cover retaining bolts securely, then connect the negative battery cable.