Positive crankcase ventilation (PCV) system [Toyota RAV4 XA20]

1. The forced crankcase ventilation system is designed to reduce hydrocarbon emissions into the atmosphere by forced removal and afterburning of crankcase gases and vapors in the cylinders. This is achieved by supplying fresh air from the air filter into the crankcase and then removing its mixture with crankcase gases and vapors through the system valve into the intake manifold.



2. The main components of the system are the valve, the in-line filter-oil separator and the vacuum hoses connecting these components to the engine. The location of the positive crankcase ventilation valve can be seen in the figure 17.1,a,b.

3. To maintain stable idle speed, the valve throttles the flow of gases at high vacuum in the intake manifold. Under poor working conditions (for example, the piston rings are worn or broken) the system directs crankcase gases through the crankcase ventilation pipe to the air filter for subsequent afterburning in the cylinders.

4. Checking and replacing the crankcase ventilation valve is described in chapter 1A.

(The article is taken from a web resource toyotaman.ru)