AUDI A6 1998 C5 / 2.G AEB ATW Engines Cooling System Components Workshop Manual

19-1


Cooling system components,
removing and installing

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 using a cloth, and
open carefully to relieve system pressure
slowly.

Note:

Cooling system is under pressure when engine
is warm. If necessary reduce pressure before
repair.
Secure all hose connections using production-
type clamps parts catalog.

VAG1921 pliers are recommended for installing
spring clips.
Always replace gaskets, seals and O-rings.
Arrows on coolant lines and hoses must
align.
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19-2


Cooling system components

Coolant hose connection diagram
1 -
Heater core
After replacing, replace coolant
2 -
Lower coolant line Removing and installing Page 19
-22
3 -
Expansion tank
With capPressure relief valve in cap, checking
Page 19
-30

4 -
Oil cooler
Removing and installing Page 17
-7 ,
item 14
5 -
Intake manifold
6 -
Lower coolant hose
7 -
Upper coolant hose
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19-3


8 -
Radiator
Removing and installing Page 19
-24
After replacing, replace coolant
9 -
Upper coolant line
10 -
Coolant pump/coolant thermostat Coolant pump, removing and installing
Page 19
-13

Check for ease of movementCoolant thermostat, removing and installing
Page 19
-20

Checking Page 19
-21
11 -
Turbocharger
12 -
Cylinder head/cylinder block
After replacing, replace coolant
13 -
Connector
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19-4

Cooling system, draining and filling


Special tools and equipment

VAG1306 drip tray
VAG1274/10 with VAG1274/1 adapter or
VAG1274/8
T40007 refractometer

Draining

Note:
Drain coolant into a clean container for recycling
or reuse.

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 using a cloth, and
open carefully to relieve system pressure
slowly.

- Open coolant expansion tank cap.

- Remove noise insulation panel (arrows).
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19-5

- Place VAG1306 drip tray underneath engine.

CAUTION!

Observe disposal regulations for coolant!

Note: - Remove retaining clip (arrow) from lower coolant hose and remove
coolant hose from radiator.

With bumper removed, coolant can be drained through radiator drain plug
(arrow).
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19-6


Filling
Note:
CAUTION! - Remove drain plug from coolant pump (arrow).
The cooling system is filled year-round with frost and corrosion
protection additives. Until 6/96, G 011 A8 C coolant (green color) was used.From 7/96 on, only G 012 A8 D coolant (red color) is used.Coolants G 011 A8 C and G 012 A8 D CANNOT be mixed. Mixing
them will cause severe engine damage. Part numbers are for reference only. Always check with your Parts
department for the latest information. If the fluid in the expansion tank is brown, G012 A8 D has been mixed
with other coolant. In this case, flush cooling system and change
coolant. To flush, fill cooling system with clear water and run engine
for approx. 2 minutes. Flushing the system should remove most of the
coolant residue.
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19-7

Note (continued from page Page 19
-6 ):

G 011 A8 C or G 012 A8 D and coolant
additives marked with "according to TL VW
774C" or "according to TL VW 774 D", prevent
frost and corrosion damage as well as calcium
deposits. They also raise the boiling point.
Therefore, cooling system must be filled year-
round with frost and corrosion protection
additives.
A higher boiling point improves engine reliability
under heavy load, particularly in countries with
tropical climates.
Frost protection additives must protect against
frost to about -25 C (-13 F) and to about -35
C (-31 F) in arctic climates.

The coolant concentration must not be reduced
by adding water even in warmer seasons and in
warmer countries. The anti-freeze ratio must be
at least 40%.
If for climatic reasons greater frost protection is
required, the amount of G 011 A8 C or G 012
A8 D can be increased, but only up to 60% to
obtain frost protection to about -40 C (-40 F).
Otherwise frost protection and cooling
effectiveness will be reduced.
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If the radiator, heater core, cylinder head or
cylinder head gasket is replaced, completely
replace the engine coolant.
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19-8


For coolant G 012 A8 D, use T40007 refractometer to test frost protection
in cooling system.
Recommended mixture ratios:
Vehicles with small cap Frost protection to
Anti-freeze amount
G 012 A8
D
1) Water
1)
-25 C
(-13 F)
-35 C
(-13 F)
40 %

50 % 3.0 ltr.
(3.2 qts.)
3.5 ltr.
(3.7 qts.) 4.0 ltr.
(4.2 qts.)
3.5 ltr.
(3.7 qts.)
1) The quantity of coolant: 7.0 liters (7.4 qts.) can vary depending upon
vehicle options.
- Install lower radiator hose and secure.
- Replace O-ring and install coolant pump drain plug.
Tightening torque: 30 Nm (22 ft lb)

- Screw VAG1274/1 adapter onto coolant expansion tank.
- Attach VAG1274/10 special tool to VAG1274/1 adapter.
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19-9

Vehicles with large cap

All models
Note:
To fill without using special tools, loosen coolant expansion tank and lift
approx. 100 mm (approx. 4 in.). - Screw VAG1274/8 adapter onto coolant expansion tank.
- Attach VAG1274/10 special tool to VAG1274/1 adapter.
- Remove grommet holding clip at heater core and pull back grommet.

- Loosen coolant hose on heater core and pull back hose sufficiently so
that bleeder hole (arrow) is no longer sealed by connection.
- Top up coolant until it flows out of coolant hose bleeder hole.
- Push coolant hose on connection and tighten.
- Install coolant expansion tank cap.
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