450 & 6.9 Models

System consists of a hose connected from air cleaner to left-hand cylinder head cover. An oil separator in cylinder head cover, idle air distributor, with either a bleeder throttle or vent valve, and a hose connecting idle air distributor with manifold.

During engine idle, blow-by gases and crankcase vapors are drawn past the bleeder throttle or vent valve, together with idle air and are passed through distribution tubes to intake manifold. At low and medium speeds, engine is supplied with air from hose in right-hand cylinder head cover.

At higher speeds, blow-by gases and crankcase vapors pass from cylinder head cover into air cleaner and into engine to be burned. To prevent freezing of bleeder throttle or vent valve, the idle air distributor is heated by engine coolant.