Oil vapours that leak from the cylinder head extension cover and build up in the sump during engine operation are channeled into a condenser/separator filter known as the blow-by filter. The filter is divided into two sections:
most of the vapours condense in the first, labyrinth section, and return to the sump;
the second section contains a coalescence filter that condenses the remaining proportion of the vapours, which return to the sump through another umbrella valve.
The uncondensed vapour proportion is sent via a MANN-HUMMEL control valve to the intake duct and burnt during normal engine operation.
