cooling AUDI A6 2000 C5 / 2.G AHA ATQ 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 with a cloth and
open carefully to relieve system pressure
slowly.

Notes:

Hoses are secured with spring-type clips. If
servicing, only use the same type of spring-type
clip.

Parts catalog

VAG1921 pliers are recommended when
installing spring-type clips.
The O-rings installed at the quick-release
connections must be replaced if damaged or
leaking.
Seals and gaskets must always be replaced.
Pa
ge 1 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

When installing coolant hoses, make sure they
are free of stress and do not come into contact
with other components (the arrows which are
located on the coolant pipes and coolant hoses
must be opposite each other).
Perform cooling system leakage test using VAG
1274 cooling system tester and 1274/9 adapter.
Pa
ge 2 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

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
Pa
ge 3 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

19-5


Cooling system components (on engine)

1 -
Connection
For thermostat
2 -
O-ring Always replace
3 -
Coolant thermostat Removing and installing page 19
-23
Note installation position page 19
-23
Checking:
Heat thermostat in waterOpening begins at approx. 86 C (187 F)Min. opening: 7 mm (0.28 in.)
4 -
Bleeder screw 20 Nm (15 ft lb)
5 -
Bolt 25 Nm (18 ft lb)
6 -
Retaining clip Make sure clip is seated securely
Pa
ge 7 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

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)
Pa
ge 8 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

19-7


14 -
O-ring
Replace if damaged
15 -
Expansion tank Check using VAG1274 cooling system
tester with VAG1274/9 adapter
16 -
Upper coolant hose Secured to radiator with retaining clipMake sure hose is securely seatedCoolant hose connection diagram page 19
-9
17 -
Coolant line
Coolant hose connection diagram page 19
-9
18 -
Rear toothed belt guard
19 -
Gasket
Always replace
20 -
Coolant pump Check for ease of movementCompletely replace if damaged or leakingRemoving and installing page 19
-20
Pa
ge 9 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

19-11

Cooling system, draining and refilling


Draining

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 coolant expansion tank cap.

- Remove noise insulation panel.
- Place VAG1306 drip tray underneath engine.

- With bumper removed, open coolant drain plug (arrow) on lower left of
radiator by turning it counterclockwise. If necessary, attach accessory
hose to connection.
-
With bumper installed, pull off retaining clamp for lower right radiator
Pa
ge 13 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

19-12


Filling
Notes: - Drain engine coolant at drain plug (arrow).
Only use coolant additive G12 (according to TL VW 7745 D). G12 is
red in color. Do not mix G12 with any other coolant additive!If the fluid in expansion tank is brown, G12 has been mixed with other
coolant. In this case, the coolant must flushed and replaced. "G12" and coolant additives marked in accordance with "TL VW 774
D" prevent frost and corrosion damage, scaling and also raise the
boiling point of the coolant. Therefore, the 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 protect against frost to about -25 C (about -
35 C 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%.
Pa
ge 15 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

19-13

Note (continued from page Page 19
-12
):

If for climatic reasons greater frost protection is
required, the amount of G 12 can be increased,
but only up to 60% (frost protection to about -
40 C), otherwise frost protection and cooling
effectiveness will be reduced.

If the radiator, heat exchanger, cylinder head or
cylinder head gasket is replaced, completely
replace the engine coolant.

Test coolant frost protection using T10007 special tool.
Recommended mixture ratios: 1) The quantity of coolant can vary depending upon the equipment
installed in the vehicle. Frost protection
to Anti-freeze
amount G 121)
Water 1)
-25 C (-13 F)
-35 C (-31 F)
40 %
50 % 2.5 l (2.7
qt.)
3.0 l (3.2
qt.) 3.5 l (3.7
qt.)
3.0 l (3.2
qt.)
Pa
ge 16 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1

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.
Pa
ge 19 of 40 Coolin
g system com
ponents, removin
g and installin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE03.19.1