Exhaust Emissions System - Crankcase Ventilation: Operation

When engine is running, crankcase fumes and vapors are vented from camshaft cover through wire mesh screen to a purge port (6-cylinder engine) or a variable orifice valve and intake manifolds depending on amount of vacuum present (V12 engine). Wire mesh screen in crankcase breather acts as a flame arrestor should a backfire occur. On all models, when engine is stopped, crankcase vapors are vented to carbon canister and stored.