Audi Workshop Service and Repair Manuals

Draining and filling cooling system

Special tools and workshop equipment required

t	Adapter for cooling system tester -V.A.G 1274/8-

t	Pipe for cooling system tester -V.A.G 1274/10-

t	Hose clip pliers -V.A.G 1921-

t	Cooling system charge unit -VAS 6096-

t	Drip tray for workshop hoist -VAS 6208-

t	Refractometer -T10007-

Draining   Note Collect drained coolant in a clean container for re-use or disposal.   WARNING Hot steam or hot coolant can escape when expansion tank is opened; cover filler cap with cloth and open carefully. –  Open filler cap on coolant expansion tank.

–  Release quick-fasteners -1- and -2- and take off front noise insulation.

–  Place drip tray for workshop hoist -VAS 6208- under engine. –  Unscrew the drain plug -arrow- at coolant hose (bottom left) and drain off coolant.

–  Pull off engine cover panel -arrows-.

–  Unbolt coolant expansion tank -arrow-. –  Unplug electrical connector for coolant shortage indicator switch -F66- at expansion tank (bottom) and move expansion tank to one side (coolant hoses -1 ... 3- remain attached).

–  Disconnect rear coolant hose from oil cooler -arrow-, and drain off remaining coolant. Filling   Note t  The cooling system is filled all year round with a mixture of water and radiator antifreeze/anti-corrosion agent. t  Use only the radiator antifreeze/anti-corrosion agent approved for this engine → Electronic parts catalogue. Other coolant additives could seriously impair in particular the anti-corrosion properties. The resulting damage could lead to loss of coolant and consequently to serious engine damage. t  The specified radiator antifreeze/anti-corrosion agent prevents frost and corrosion damage and stops scaling. Such additives also raise the boiling point of the coolant. For these reasons the cooling system must be filled all year round with the correct antifreeze and anticorrosion additive. t  Because of its high boiling point, the coolant improves engine reliability under heavy loads, particularly in countries with tropical climates. t  Frost protection is required down to about –25 °C (in countries with arctic climate: down to about –35 °C). t  The coolant concentration must not be reduced by adding water even in warmer seasons and in warmer countries. The antifreeze concentration must be at least 40 %. t  If greater frost protection is required in very cold climates, the concentration of radiator antifreeze/anti-corrosion agent can be increased, but only up to 60% (this gives frost protection to about –40 °C). If the concentration exceeds 60%, frost protection decreases again and cooling efficiency is also impaired. t  Use only clean tap water for mixing coolant. t  Do not use drained coolant again if: t  the radiator, heat exchanger for heater, cylinder head, cylinder head gasket or cylinder block have been renewed. t  the coolant is contaminated or dirty. t  For checking anti-freeze protection in cooling system, use refractometer -T10007-. t  Secure all hose connections with the correct type of hose clips (same as original equipment) → Electronic parts catalogue.

–  Connect coolant hose to oil cooler -arrow-.

–  Close drain plug -arrow-.

–  Fill reservoir of cooling system charge unit -VAS 6096- with at least 9 litres of premixed coolant (based on recommended ratio): l  Radiator antifreeze/anti-corrosion agent (40 %) and water (60 %) for frost protection to –25 °C. l  Radiator antifreeze/anti-corrosion agent (50 %) and water (50 %) for frost protection to –35 °C l  Radiator antifreeze/anti-corrosion agent (60 %) and water (40 %) for frost protection to –40 °C. –  Run vent hose -1- into a small container -2-. (The vented air draws along a small amount of coolant, which should be collected.) –  Close the two valves -A- and -B- by setting lever at right angle to direction of flow. –  Connect hose -3- to compressed air. l  Pressure: 6 ... 10 bar.

–  Open valve -B- by setting lever in direction of flow. The suction jet pump generates a partial vacuum in the cooling system. l  The needle on the gauge should move into the green zone. –  Also briefly open valve -A- (turn lever in direction of flow) so that hose on reservoir -VAS 6096/1- can fill with coolant. –  Close valve -A- again. –  Leave valve -B- open for another 2 minutes. l  The suction jet pump will continue generating a vacuum in the cooling system. l  The needle on the gauge should remain in the green zone. –  Close valve -B-. l  The needle on the gauge should stop in the green zone. The vacuum level in the cooling system is then sufficient for subsequent filling. If the needle does not reach the green zone, repeat the process. If the vacuum level drops, there is a leak in the cooling system. –  Detach compressed air hose. –  Open valve -A-. The partial vacuum in the cooling system causes the coolant to be drawn up out of the reservoir -VAS 6096/1-; the cooling system is then filled. –  Detach cooling system charge unit -VAS 6096- from expansion tank.

–  Fit pipe -V.A.G 1274/10- onto adapter -V.A.G 1274/8-.

–  Release coolant hose going to heat exchanger and pull back hose until bleeder hole in hose -arrow- is no longer blocked by the connection. –  Top up the coolant until it emerges from the bleed hole in the coolant hose without bubbles. –  Push coolant hose onto connection and secure with hose clip. –  On vehicles with auxiliary heater, switch heater on (for about 30 seconds) and then off again. –  Tighten filler cap on expansion tank. –  Start engine. –  Set temperature to “HI”. –  Switch off air conditioner compressor (press ECON button). –  Run the engine for 3 minutes at 2000 rpm. –  Allow the engine to run at idling speed until the two large coolant hoses at main radiator become warm. –  Run the engine for 1 minute at 2000 rpm. –  Switch off ignition and allow engine to cool down.

–  Check coolant level. l  The coolant level must be at the MAX marking when the engine is cold. l  The coolant level can be above the MAX marking when the engine is warm.