1977-79 320i

This is a sealed system and does not allow entry of fresh air into the crankcase. Crankcase vapors and blow-by gases are drawn from the crankcase up to the cylinder head cover and into a hose which runs to the inlet manifold side of the air cleaner. From there, the gases travel through the intake manifold into the engine and are reburned with the fresh incoming air/fuel mixture. Suction created by the running engine has a vacuuming effect on the crankcase and because it is a sealed system, no fumes or gases can escape into the atmosphere.