Operating principle
The principle of operation of the controlled crankcase ventilation system (PCV) shown in the accompanying illustration.
1 - intake air; 2 - oil filler cap (sealed); 3 - PCV valve; 4 - measuring probe (hermetically sealed); 5 - crankcase evaporation
The crankcase vapors, which include gases that have escaped from the combustion chambers bypassing the piston rings, enter the oil separator unit located in the cylinder head cover. Oil is returned to the engine through the drain holes, and clean air is supplied to the oil separator through a hose from the air cleaner. Air is mixed with crankcase gases and through the ventilation control valve (PCV) enters the intake manifold, and from there - into the combustion chambers.
The system operates most efficiently at high engine speeds, when a shallow depression in the intake manifold allows the PCV valve to open fully. Accordingly, with closed throttle valves, when a deep vacuum is formed in the intake piping, the effectiveness of crankcase ventilation is minimal.
In a heavily worn engine, when the level of gases escaping into the crankcase from the combustion chambers is high, part of the crankcase vapor enters the air cleaner, regardless of the position of the throttle valves.
Service
Note. The system is subject to regular maintenance. Particular attention should be paid to the points listed below.
1. Check the patency and condition of the rubber hoses of the system. Replace defective ones.
2. Check up a condition of sealing linings of a mouth of the gulf of impellent oil and a measuring probe. Replace defective and/or suspicious seals.
3. Check the PCV valve for proper operation.
PCV valve function test
1. Disconnect the PCV hose from the cylinder head cover.
2. Start the engine and leave it running at idle.
3. Press your finger against the open end of the hose (see accompanying illustration). Vacuum should be felt, otherwise the PCV valve is blocked. Clean the valve or replace it.
Note. The location of the PCV valve on 3.0L engines is shown in the accompanying illustration.