Audi Q7 e-tron quattro 4M - Page 59

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Coolant feed
Coolant run-on pump V51
(not intended for the 3.0l V6 TDI engine, this
pump is used in combination with the third-
generation 2.0l R4 TFSI engine)
ATF coolant thermostat
ATF cooler
Coolant return
open
closed
Thermocouple with lift pin
649_114
649_111
649_121
The coolant thermostat is integrated in the coolant return line of
the ATF cooler.
A groove in the valve seat ensures a continuous trickle flow of
coolant. When the coolant temperature increases, the wax in the
thermocouple heats up and expands.
As a result, the valve seat opens via the lift pin at a temperature of
above 80°C, and the coolant circuit is opened.
Note:
When installing the coolant thermostat, always pay attention to
direction of flow. This is indicated by an arrow on the housing.
Fitting the coolant thermostat in the wrong position will adversely
aect temperature regulation and impair ATF cooling.
Clogging of the groove in the valve seat will disrupt the continuous
trickle flow of coolant. In this case, the thermocouple will not be
heated to the required level. The valve seat remains closed and the
ATF is not cooled.
In case of complaints concerning excessively high ATF tempera-
ture, check the coolant circuit and the oil circuit to the ATF cooler,
as well as the coolant thermostat.
Coolant run-on pump V51
V478
The coolant run-on pump V51 is used in combination with the
third-generation 2.0l R4 TFSI engine.
The pump electronics are provided with a continuous supply of
voltage via the 12-volt electrical system. Pump output is control-
led by the engine control unit according to ATF temperature. The
PWM signal used for this purpose is also used, conversely, by the
pump electronics in order to indicate any irregularities to the
engine control unit. This information is stored in the event
memory. The pump can be checked by running an actuator test via
the engine control unit.
Discrete line from engine control unit J623,
with bidirectional PWM signal
ATF coolant thermostat
ATF return line
ATF supply line
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