coolant temperature AUDI A4 1996 B5 / 1.G AHA ATQ Engines Cooling System Components Workshop Manual

19-2


Cooling system components (on body)

1 -
Radiator
Removing and installing page 19
-17
After replacing, completely replace coolantWith ATF cooler on vehicles with automatic
transmission
2 -
Securing clip
3 -
Securing rubber
4 -
O-ring Replace if damaged
5 -
Lower coolant hose Secured to radiator with retaining clipMake sure hose is securely seatedCoolant hose connection diagram page 19
-9
6 -
Securing clip
To secure temperature switch in coolant
hose
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19-3


7 -
O-ring
Replace if damaged
8 -
Coolant Fan Control (FC) thermal switch -
F18- 35 Nm (26 ft lb)For electric coolant fan
Switching temperatures, stage 1:On: 92-97 C (198-207 F)Off: 84-91 C (183-196 F)
Switching temperatures, stage 2:
On: 99-105 C (210-221 F)Off: 91-98 C (196-208 F)
9 -
Locking bolt
10 -
10 Nm (7 ft lb)
11 -
Fan ring
Clipped into air ducting and secured with
locking 9 bolt
12 -
2-pin harness connector
13 -
Coolant fan -V7- Checking page 19
-26
14 -
Rubber washer
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19-6


7 -
Engine Coolant Temperature (ECT) sensor
-G62-
For Engine Control Module (ECM)If necessary, release pressure in cooling
system before removing Checking Repair Manual, 2.8 Liter V6
5V Fuel Injection & Ignition, Repair Group
01
8 -
Rear coolant line
Coolant hose connection diagram page 19
-9
9 -
Lifting eye
10 -
10 Nm (7 ft lb)
11 -
Coolant line
Coolant hose connection diagram page 19
-9
12 -
Front coolant hose
Coolant hose connection diagram page 19
-9
13 -
Sealing cap
Check using VAG1274 cooling system
tester with VAG1274/8 adapter Test pressure: 1.4-1.6 bar (20-23 psi)
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19-16

- Raise engine speed to approx. 2000 rpm for
approx. 5 minutes.

- Allow engine to idle until lower coolant hose on
radiator is hot.

- Check coolant level and top-off if necessary.
When engine is at normal operating
temperature, coolant level must be on MAX
mark. When engine is cold, coolant level must
be between MIN and MAX marks.

WARNING!

The cooling system is pressurized when the
engine is warm. When opening the expansion
tank, wear gloves and other appropriate
protection, cover the cap with a cloth and
open carefully to relieve system pressure
slowly.
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19-17

Radiator, removing and installing


Removing

- Remove front bumper.

Repair Manual, Body Exterior, Repair Group
63


- Drain coolant at drain plug (arrow) page 19
-11
.

Vehicles with automatic transmission - Disconnect coolant hoses at radiator, unhinge clamp from connection
flange (arrow).
- Disconnect connector from temperature switch at bottom-left of
radiator.
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19-28

Cooling system, pressure test


Engine at operating temperature

WARNING!

The cooling system is pressurized when the
engine is warm. When opening the expansion
tank, wear gloves and other appropriate
protection, cover the cap with a cloth and
open carefully to relieve system pressure
slowly.

- Open cap on coolant expansion tank.

- Using VAG1274/8 adapter attach VAG1274 cooling system tester to
coolant expansion tank.
- Use tester hand pump to create a pressure of approx. 1.0 bar (14.5
psi).
- If pressure falls, check for leaks and repair.
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19-32

After-run coolant pump, checking


Note:

Control modules with an after-run time of 15
seconds after engine is turned off were installed
since start of production. As a running change
in m.y. 1999, control modules with an after-run
time of 3 minutes were installed.
The coolant after-run pump also continues to
run after the engine is started again before the
15 second or 3 minute cycle is completed.
The coolant after-run pump and the after-run
fan are controlled via the same control module.
After switching off the engine, the after-run pump
always runs for 15 seconds or 3 minutes after the
engine has been switched off. If during this time
the switch-on temperature of 102 C (coolant
temperature) is reached at the thermostat of the
second fan stage, the after-run pump continues
to run and the coolant fan continues to run in the
after-run stage until the switch-off temperature of
91 C of the coolant at thermostat has been
reached. The maximum running time of the after-
run pump is 10 minutes.
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