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.

–  Vehicles with auxiliary heater: remove bolts -arrows- securing exhaust pipe for auxiliary/additional heater to noise insulation.

–  Open quick-release fasteners -1 … 3- and take off front and rear noise insulation.

–  Place drip tray for workshop hoist -VAS 6208- under engine. –  Disconnect coolant hose -arrow- from coolant pipe (left-side) and drain off coolant.

–  Detach coolant hose (bottom right) from radiator -arrow-.

–  Disconnect coolant hoses -arrows- behind engine (right-side) and drain off remaining coolant. 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 for reasons of climate, the coolant concentration can be increased up to a maximum of 60% (this gives frost protection down to about –40 °C). Otherwise frost protection decreases again and cooling efficiency also becomes worse. 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  To check anti-freeze protection in cooling system, use refractometer -T10007-. 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   Note Shown in illustration with gearbox removed.

–  Connect coolant hoses -arrows- with plug-in connector to coolant pipes (rear right).

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

–  Always remove old O-ring -2- from coolant hose -3-. –  Lubricate new O-ring with coolant additive and fit O-ring in coolant hose. –  Press coolant hose onto radiator -1- or coolant pipe until it engages with a click. –  Press coolant hose in again and then pull to check that plug-in connector is correctly engaged.

–  Connect coolant hose -arrow- at coolant pipe (left-side).

–  Fill reservoir of -VAS 6096- with at least 12 litres of premixed coolant (according to recommended ratio): –  Screw adapter -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-. (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 charge unit reservoir -VAS 6096- 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 vacuum in the cooling system causes the coolant to be drawn out of the reservoir for cooling system charge unit -VAS 6096-; 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-.

–  Carefully pull engine cover panel off four retaining pins one after the other -arrows-.

–  Detach exhaust gas recirculation valve -N18--arrow- from retainer.

–  Unscrew bleeder screw -arrow- at front of engine. –  Fill up with coolant until it comes out at bleeder hole with no air bubbles. –  Close the bleeder screw.

–  Loosen 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 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. Tightening torque

Component	Nm
Bleeder screw to coolant pipe	8