See Figures 1, 2, 3, 4 and 5
The Positive Crankcase Ventilation (PCV) system is used on all vehicles covered by this information. The PCV system vents harmful combustion blow-by fumes from the engine crankcase into the engine air intake for burning with the fuel and air mixture. The PCV system maximizes oil cleanliness by venting moisture and corrosive fumes from the crankcase.
All of the vehicles covered by this information, except for the 3.0L and the 3.2L SHO engines, utilize a PCV valve. The PCV valve limits the fresh air intake to suit the engine demand and also serves to prevent combustion backfiring into the crankcase. The PCV valve controls the amount of blow-by vapors pulled into the intake manifold from the crankcase. It also acts as a one-way check valve that prevents air from entering the crankcase in the opposite direction.
The PCV system on the SHO vehicles is unique because is does not use a PCV valve. Instead, the crankcase gases flow through an oil separator to three ports in the throttle body. Fresh air for the PCV system is supplied from another port on the throttle body to the cylinder head cover. Under various throttle conditions, the air and crankcase gases flow differently through the ports in the throttle body.
On some engine applications, the PCV system is connected with the evaporative emission system. Do not remove the PCV system from the engine, as doing so will adversely affect fuel economy and engine ventilation, with resultant shortening of engine life.
The components used in the PCV valve system consist of the PCV valve (or tube as in SHO applications), the rubber mounting grommet in the valve cover, the nipple in the air intake system and the necessary connecting hoses.
- 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 caused by loose engagement, hose splitting, cracking, kinking, nipple damage, poor 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.
- 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 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 so equipped, is leaking. If the evaporative emission valve is suspected of leaking, proceed to Step 5.
- Disconnect the evaporative hose, if equipped, 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 system: oil cap, PCV valve, hoses, cut grommets, the oil separator on the 2.5L engine and valve cover for bolt torque/gasket leak.
REMOVAL & INSTALLATION
- Remove the PCV valve from the mounting grommet in the valve cover.
- Disconnect the valve from the PCV hose and remove the valve from the vehicle.
- Installation is the reverse of the removal procedure.