Positive Crankcase Ventilation (PCV) System

PCV System Components

The positive crankcase ventilation system is designed to reduce hydrocarbon emissions by purging the crankcase and then drawing off crankcase gases. Fresh air taken from the air cleaner is mixed inside the engine with crankcase gases and directed through the PCV valve for combustion in the engine cylinders.
The main components of the system are the PCV valve, the air intake passage, and the connecting hoses.
To maintain stable engine operation at idle, the PCV valve restricts the flow of crankcase gas mixture when vacuum in the intake manifold is low. If normal engine operation is disturbed (for example, due to worn piston rings), excess crankcase gases are directed back through the ventilation pipe into the air cleaner for combustion in the combustion chamber.
The gas and air mixture enters the throttle body. Over time, resinous deposits form in the area near the throttle valve. These deposits should be removed periodically.

Inspection

PROCEDURE
1. To check the PCV valve, remove it from the rubber boot in the cylinder head cover and shake it. If a rattle is heard, the valve is not clogged with resin deposits and is serviceable. If there is no rattle, replace the PCV valve.
2. Start the engine and set it to idle, then place your finger on the PCV valve. If vacuum is felt, the PCV valve is serviceable. If no vacuum is felt, either the PCV valve is faulty or the PCV valve hose is clogged. Also check for air leaks at the PCV valve, the oil filler neck and the other hoses.

Replacement

PROCEDURE
1. Remove the PCV valve. Check the rubber boot of the PCV valve for cracks, hardening and mechanical damage. If damage is found, replace the boot.
2. If the PCV valve is clogged, the hose is most likely clogged as well. Remove the hose and clean it in solvent.
3. After cleaning the hose, check for signs of wear and mechanical damage. Make sure the hose fits tightly onto the fittings.
4. If necessary, replace the PCV valve.
5. Install the cleaned PCV valve hose. Make sure the hose fits securely on the PCV valve.