Engine crankcase and fuel tank ventilation system (BMW X5 E53)

The concentration of hydrocarbons in the engine crankcase and fuel tank can be many times higher than that recorded in the exhaust gases. The crankcase ventilation system directs crankcase gases into the intake manifold, and the oil separation system allows part of the oil to be returned to the oil pan (Fig. 4.23).



Crankcase gases enter the combustion chamber for afterburning.

The fuel tank ventilation system (Fig. 4.24) directs fuel tank vapors into the adsorber, which is purged with atmospheric air and gasoline vapors enter the intake manifold for afterburning.