Audi 4.2-litre V8 FSI, Service Training

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Note
Modifications after start of production
In both engines, the separated oil flows
into the crankcase through the cover in the
inner vee adjacent the crankcase breather
(no longer through the chain housing).
In the Q7 engine the crankcase is vented
through a single chamber, i.e. via bank 2
only. Better antiicing protection is achieved
in this way.
After the blow-by gas has passed through the fine
oil separator, the gas flows into the intake manifold
downstream of the throttle valve.
This inlet point is integrated in the coolant circula-
tion system and heated. This prevents the crankcase
breather from freezing up.
Engine mechanicals
Crankcase ventilation
The crankcase is ventilated through both cylinder
heads.
The valve hoods incorporate a large settling space.
This space acts as a gravity-type oil separator.
A fine oil separator is connected to the valve hoods
by means of plastic hoses.
A control piston, a bypass valve, a two-stage
pressure limiting valve and an oil drain valve are
integrated in the oil separator housing.
Pressure limiting valve
Heater
Bypass valve
Fine oil separator
Crankcase breather system
Non-return valve
(crankcase breather)
Breather pipe
Breather pipe