Crankcase Ventilation System
WARNING: This page is about a different car, the 2018 Land Rover Range Rover, 2017 Land Rover Range Rover, and 2016 Land Rover Range Rover. However, it is still accessible from the selected car via links, so may be relevant.
Clean air being drawn into the primary turbocharger when the engine is running creates a vacuum in the ventilation tube and hose assembly. This vacuum in turn creates a vacuum in the oil separator and draws gasses from the crankcase and camshaft covers into the separator. The gasses are circulated around the oil separator, allowing oil particles to be separated from the gas. The gasses are drawn into the ventilation tube and hose assembly and are mixed with the clean air being drawn into the turbocharger. The oil drains out of the oil separator, and down through the high pressure fuel pump mounting bracket and cylinder block into the oil pan.