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   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. –  Remove noise insulation → Rep. Gr.66. Cabriolet –  Remove noise insulation frame → Rep. Gr.50. All models:

–  Remove air pipe -item 1 and 2-.   Note

Collect drained coolant in a clean container for re-use or disposal. –  Place drip tray for workshop hoist -VAS 6208- beneath engine. –  Disconnect coolant hose -1- from radiator (bottom) and drain off coolant.   Note Disregard item -2-.

–  Disconnect bottom coolant hose leading to continued coolant circulation pump -V51--arrow- and drain off coolant.

Vehicles with auxiliary heater: –  Disconnect coolant hoses -arrows- and drain off remaining coolant.   Note Disregard items marked -1 and 2-. Filling   Note t  The cooling system is filled all year round with a mixture of water and coolant additive. Mixture ratio → Anchor. t  Use only the coolant additive listed in the → 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 coolant (based on recommended mixture ratio) → Anchor 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 coolant 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 coolant concentration must be at least 40 %. t  If greater frost protection is required in very cold climates, the concentration of coolant additive 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  If radiator, heat exchanger, cylinder head, cylinder head gasket or cylinder block have been renewed, do not re-use old coolant. 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. Recommended mixture ratio for coolant l  Coolant (40 %) and water (60 %) for frost protection to –25 °C l  Coolant (50 %) and water (50 %) for frost protection to –35 °C l  Coolant (60 %) and water (40 %) for frost protection to –40 °C t  Coolant → Electronic parts catalogue

–  Connect bottom coolant hose -1- to radiator.

–  Connect the coolant hose to the continued circulation coolant pump -V51--arrow-.

Vehicles with auxiliary heater: –  Connect coolant hoses -arrows-.   Note Disregard items marked -1 and 2-. All vehicles: –  Fill reservoir of -VAS 6096- with at least 10 litres of premixed coolant (according to recommended ratio → Anchor). –  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.

–  Check coolant level. –  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. –  Close filler cap on coolant expansion tank. –  Start engine and run at approx. 3000 rpm until radiator fan cuts in.   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. –  Check coolant level. l  When the engine is at normal operating temperature, coolant level must be at “max” mark, when engine is cold it must be between “min” and “max” marks. –  Top up with coolant again if necessary. –  Switch off engine.