Cooling System; Cooling System In Audi Q7 - Audi 4.2-litre V8 FSI Service Training

Cooling system

Cooling system in the Audi Q7
Alternator
Radiator
The cooling system in the new V8 engines was
configured as a longitudinal-flow cooling system.
The cooling water flows in on the outlet side and
through the cylinder head gasket into the cylinder
head, where it flows out longitudinally through the
chain housing cover.
Cooling of the cylinder webs was improved by
drilling coolant ducts with optimised cross-sec-
tional area into the webs.
Forced flow through these bores is ensured by
means of specially sealed water ducts.
The high-revving engine also has two vee-shaped
forced-flow bores between the inlet valves because
they are subjected to higher stresses due to the
high power density.
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Expansion tank
Coolant temperature sender
Oil cooler Thermostat
A map-controlled coolant thermostat is used in the
basic engine.
When operating at full throttle the coolant tempera-
ture is reduced to 90 °C via an electrically heated
thermostat to avoiding increasing the tendency of
the engine to knock. When operating at part throttle
- which is not critical with regard to knock - the
coolant temperature is increased to 105 °C.
The thermodynamic advantages and the reduced
friction result in a fuel saving of approx. 1.5 % when
operating at low part throttle.
Radiator fan control
The engine control unit J623 activates radiator fan
control unit J293 and radiator fan control unit 2 J672
by generating a separate PWM signal.
The radiator fan control units then energise the
radiator fans based on the engine control unit
signal by means of a PWM signal.
The radiator fan is activated by the engine control
unit based on a characteristic map.
Heater heat exchanger
Coolant pump
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