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/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 expansion tank with cloth and open carefully. –  Open filler cap on expansion tank.

–  Open quick-release fasteners -A- and -B- and detach noise insulation (front). –  Place drip tray for workshop hoist -VAS 6208- beneath engine.

–  Lift retaining clip -arrow- and disconnect coolant hose (bottom) from radiator.   Note

When the bumper and the air duct for the charge air cooler are removed from the vehicle, the coolant can also be drained from the radiator via the drain plug -arrow-.

–  Open drain plug -arrow- and drain off coolant.

–  Unbolt coolant expansion tank -arrows 1-. –  Detach wire for coolant shortage indicator switch -F66- and move coolant expansion tank to one side with coolant hoses -2- attached.

–  Detach coolant hose -arrow- and press downwards to 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 anticorrosion 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  radiator, heat exchanger for heater, cylinder head and cylinder head gasket or cylinder block have been renewed. t  the coolant is contaminated or dirty. t  Contaminated or dirty coolant must not be used again. 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 radiator with plug-in connector. –  Remove old O-ring -2- from coolant hose -3-. –  Lightly lubricate new O-ring with coolant and fit O-ring in coolant hose. –  Press coolant hose onto radiator -1- until it engages with a click. –  Press coolant hose in again and then pull to check that plug-in connector is correctly engaged.

–  Renew seal and tighten drain plug -arrow-. l  Tightening torque: 10 Nm. –  Install and secure coolant hose to oil cooler/coolant pipe (top).

–  Fill reservoir of cooling system charge unit -VAS 6096- with at least 10 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 l  Radiator antifreeze/anti-corrosion agent → Electronic parts catalogue –  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 adapter -V.A.G 1274/8- on coolant expansion tank.

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

–  If fitted, remove seal from plenum chamber cover -arrows-. –  Detach plenum chamber cover -1- towards the front.

–  Unclip retaining clip securing boot at connection for heat exchanger and pull back boot. –  Release coolant hose going to heat exchanger and pull back hose until bleeder hole in hose -arrow- is no longer blocked by the connection. –  Fill up with coolant until it flows out at bleeder hole in coolant hose. –  Push coolant hose back onto connection and secure with hose clip. –  Close filler cap on expansion tank. –  Start engine. –  Run engine for 3 minutes at 2000 rpm. –  Then allow engine to idle until bottom coolant hose at radiator becomes hot. –  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.