ect AUDI A6 1998 C5 / 2.G AHA ATQ Engines Cooling System Components User Guide

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
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CAUTION!
Follow disposal regulations for coolant. hose (from radiator to engine) and disconnect radiator hose from
radiator.
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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%.
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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.)
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19-14

- Replace coolant drain plug O-ring and install
coolant drain plug into engine.

Tightening torque: 20 Nm (15 ft lb).

- Install lower right coolant hose and secure with
retaining clip.

- Secure coolant drain valve to radiator.

- Screw VAG1274/9 onto expansion tank and insert VAG1274/10 into
adapter.

- Loosen clamp on coolant hose on heater core and pull back hose until
bleeder hole in coolant hose (arrow) is no longer sealed by connection.
- Top off coolant until it flows out from bleeder hole in coolant hose.
- Push coolant hose onto connection and tighten.
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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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19-18

All models

Vehicles with air conditioning
CAUTION! - Unbolt power steering hydraulic oil cooling line (arrows).
DO NOT open the air conditioning refrigerant circuit.Disconnect A/C refrigerant lines at brackets and support points
only. Avoid damage from bending. Refrigerant lines kink easily.

- Unbolt air guides at radiator -4- on left and right-sides.
- Unbolt retaining bolts -1- and -2- from condenser.
- Disconnect harness connector -3- at A/C pressure switch -F129-.
- Pull condenser upward out of retaining bracket, swing to side and hang
at right-front wheel using wire loop.
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19-20

Coolant pump, removing and installing


Notes:

Always replace seals and gaskets.
Cover the toothed belt with a cloth to protect it
from coolant before removing the coolant pump.

Removing

- Remove front bumper.

Repair Manual, Body Exterior, Repair Group
63


- Move lock carrier into service position.

Repair Manual, Body Exterior, Repair Group
50


- Remove ribbed belt page 13
-8 .

- Remove toothed belt page 13
-12
.
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19-23

Thermostat, removing and installing


Notes:

Always replace seals and gaskets.
Cover the toothed belt with a cloth to protect it
from coolant before removing thermostat.

Removing

- Drain coolant page 19
-11
.

- Remove front bumper.

Repair Manual, Body Exterior, Repair Group
63


Lock carrier in service position

Repair Manual, Body Exterior, Repair Group
50


- Remove ribbed belt page 13
-8 .
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