Crankcase Ventilation Systems: Operation
When the engine is running, crankcase vapors are drawn from the valve cover area through the purge tube and into the intake manifold. The wire mesh screen acts as a flame arrestor in case of a backfire. The purge hose is also connected to the charcoal canister, and simultaneously purges the fuel evaporation system. When the engine is stopped, fumes from the crankcase go into the canister.