The Positive Crankcase Ventilation (PCV) system cycles crankcase gases back through the engine, where they are burned. The PCV valve regulates the amount of ventilating air and blow-by gas to the intake manifold and prevents backfire from traveling into the crankcase. For most vehicles, this system is comprised of a PCV valve connected to a tube or hose that goes from a grommet in the valve cover to the throttle body. On some engines, such as the 3.0L and 3.2L SHO, the system simply consists of a tube routed from the valve cover to the throttle body.
- Visually inspect the components of the PCV system. Check for rough idle, slow starting, high oil consumption and loose, leaking, clogged or damaged hoses.
- Check the fresh air supply hose and the PCV hose for air leakage or flow restriction due to loose engagement, hose splitting, cracking or kinking, nipple damage, rubber grommet fit or any other damage.
- If a component is suspected as the obvious cause of a malfunction, correct the cause before proceeding to the next step.
- If all checks are okay, proceed to the pinpoint tests.
- If equipped, remove the PCV valve from the valve cover grommet and shake the valve. If the valve rattles when shaken, reinstall and proceed to Step 2. If the valve does not rattle, it is sticking and should be replaced.
- Start the engine and bring it to normal operating temperature.
- On the 2.5L engine, remove the corrugated hose from the oil separator nipple. On all other engines, disconnect the hose from the remote air cleaner or air outlet tube.
- Place a stiff piece of paper over the nipple or hose end and wait 1 minute. If vacuum holds the paper in place, the system is okay; reconnect the hose. If the paper is not held in place, the system is plugged or the evaporative emission valve (if equipped) is leaking. If the evaporative emission valve is suspected of leaking, proceed to Step 5.
- If equipped, disconnect the evaporative hose, and cap the connector.
- Place a stiff piece of paper over the hose/nipple, as in Step 4, and wait 1 minute. If vacuum holds the paper in place, proceed to evaporative emission system testing. If the paper is not held in place, check for vacuum leaks/obstruction in the oil cap, PCV valve and hoses, or for split grommets. Also check the oil separator on the 2.5L engine and valve cover for a gasket lead or incorrect bolt torque.
REMOVAL & INSTALLATION
2.5 and 3.0L Engines-Except SHO
See Figures 1 and 2
- Remove the fuel vapor hose and the crankcase ventilation hose from the PCV valve.
- Remove the PCV valve from the PCV valve grommet.
- Inspect the valve and grommet for deterioration, and replace if necessary.
- Install the PCV valve into the valve grommet, then connect the fuel vapor and crankcase ventilation hoses.
See Figure 3
- Loosen the crankcase ventilation tube clamps.
- Carefully disconnect the tube from the left-hand side valve cover fitting and the throttle body.
- Inspect the crankcase ventilation tube for deterioration and replace if necessary.
- Connect the tube to the valve cover fitting and the throttle body, then secure with the retaining clamps.
See Figure 4
- Disconnect the crankcase ventilation tube from the PCV valve.
- Remove the valve from the PCV valve grommet.
- Inspect the PCV valve and grommet for deterioration, and replace if necessary.
- Install the PCV valve into the valve grommet, then connect the crankcase ventilation tube.