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	Drip tray for workshop hoist -VAS 6208-

t	Hose clip pliers -V.A.G 1921-

t	Cooling system charge unit -VAS 6096-

t	Refractometer -T10007-

Draining   Note Collect drained coolant in a clean container for re-use or disposal.

–  Detach bonnet → Chapter.   WARNING Hot steam/hot coolant can escape - risk of scalding. t  The cooling system is under pressure when the engine is hot. t  To allow pressure to dissipate, cover filler cap on coolant expansion tank with cloth and open carefully. –  Open filler cap -arrow- on coolant expansion tank.

–  Release fasteners -arrows- and remove noise insulation.

–  Place drip tray for workshop hoist -VAS 6208- beneath engine. –  Lift retaining clip, disconnect coolant hose -arrow- from radiator (bottom) and drain off 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-.

–  Connect coolant hose -arrow- with plug-in connector to radiator → Anchor.

–  Fill reservoir of -VAS 6096- with at least 8 litres of premixed coolant (according to 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. –  Fit adapter for cooling system tester -V.A.G 1274/8- onto coolant expansion tank. –  Attach cooling system charge unit -VAS 6096- to adapter -V.A.G 1274/8-. –  Run vent hose -1- into a small container -2-.   Note The vented air draws along a small amount of coolant, which should be collected. –  Close both valves -A- and -B- (turn lever at right angles 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. l  The suction jet pump generates a partial vacuum in the cooling system; 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 of -VAS 6096- can fill with coolant. –  Close valve -A- again. –  Leave valve -B- open for another 2 minutes. l  The suction jet pump continues to generate a partial vacuum in the cooling system; 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.   Note t  If the needle does not reach the green zone, repeat the process. t  Check cooling system for leaks if the vacuum is not maintained. –  Detach compressed air hose. –  Open valve -A-. l  The vacuum in the cooling system causes the coolant to be drawn out of the reservoir of -VAS 6096-; the cooling system is then filled. –  Detach cooling system charge unit -VAS 6096- from coolant expansion tank.

–  Top up coolant to „max“ mark. –  Start engine and run for 2 minutes (maximum) at approx. 1500 rpm. –  Top up coolant to overflow hole on expansion tank with engine running. –  On vehicles with auxiliary heater, switch heater on (for about 30 seconds) and then off again. –  Start engine and run for 2 minutes (maximum) at approx. 1500 rpm. –  Top up coolant to overflow hole on expansion tank with engine running.

–  Close filler cap -arrow- on expansion tank. –  Allow engine to run at idling speed until two large coolant hoses at radiator become warm. –  Switch off ignition and allow engine to cool down. –  Install noise insulation → Rep. gr.50.

–  Check coolant level. l  The coolant level must be between the „min“ and „max“ markings when the engine is cold. l  The coolant level can be at the „max“ marking when the engine is warm. –  Top up with coolant again if necessary.