General information
The PCV system, which is included in the mandatory package of engines of all models considered in this Manual, serves to reduce the emission of hydrocarbon compounds into the atmosphere by removing crankcase gases from the engine. The unit is purged by forcing fresh air coming from the air cleaner through the crankcase, where it mixes with accumulated fumes and gases escaping from the combustion chambers and is discharged through the PCV valve into the intake manifold. The principle of operation of the controlled crankcase ventilation system is shown in the illustration.
The main components of the system are the PCV valve, air intake and a set of hoses connecting these devices to the engine.
In order to maintain stable idle speed, the PCV valve shuts off the purge flow when the intake manifold is under vacuum, valve failure can lead to unexpected engine shutdowns and sudden changes in speed.
Violation of the functioning of the crankcase ventilation system can lead to a violation of stability / a decrease in idling speed, up to spontaneous engine shutdown, the development of oil leaks, and the formation of a tarry coating on the internal surfaces of the unit.
Check of serviceability of functioning of the valve of PCV
1. Disconnect the ventilation hose from the PCV valve. Remove the valve from the engine (unscrew it or remove it from the mounting sleeve in the cylinder head cover). After removing the valve, reconnect the ventilation hose to it.
2. Start the engine at idle and press your finger against the hole in the valve - there should be a vacuum inside the assembly.
3. If vacuum is not felt, first check the passage of the hose, then (if the hose is ok), turn off the engine, release the valve from the hose and use a thin rod to check the freedom of movement of its plunger - the rod is inserted into the hole with the threaded assembly side.
Note. When shaken, a serviceable valve should make a crackling noise.
4. If necessary, replace the valve assembly.
Replacement
1. Unscrew the valve from its socket in the cylinder head cover, or by pulling it vertically up, remove it from the rubber seat sleeve. Assess the condition of the bushing, replace if necessary.
2. If the valve is clogged with tarry deposits, it is also possible that the connecting hose is blocked, remove the hose and flush it with a solvent.
3. After flushing the hose, check it for signs of material aging and mechanical damage. Track reliability of fixing of a hose on receiving unions.
4. If necessary, replace the PCV valve.