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 –  Remove bonnet → Chapter.   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 -arrow- on coolant expansion tank.

–  Remove noise insulation -arrows-.

–  Place drip tray for workshop hoist -VAS 6208- under engine. –  Disconnect coolant hose (bottom) at radiator -arrow- and drain off coolant.   Note Disregard -item 1-.

–  Disconnect coolant hose from oil cooler -arrow-, guide downwards 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  It is important to use only coolant additive Plus -G 012 A8F A1- (also designated as “G12+”) “meeting specification TL VW 774 F”. 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  Coolant additive “G12+” may be mixed with additives “G11” and “G12”. t  “G12+” and coolant additives marked “Conforming with specification TL VW 774 F” prevent frost and corrosion damage and stop scale from forming. 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 amount of “G12+” can be increased, but only up to 60% (this gives frost protection to about –40 °C). If antifreeze 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  Secure all hose connections with the correct type of hose clips (same as original equipment) → Parts catalogue. t  To check frost protection level of coolant additive “G12+” you must use a refractometer -T10007-.

–  Connect coolant hose to lower part of radiator -arrow-.   Note Disregard -item 1-.

–  Fill reservoir of cooling system charge unit -VAS 6096- with at least 6 litres of premixed coolant (based on recommended ratio): l  “G12+” (60 %) and water (40 %) for frost protection to –25 °C. l  “G12+” (50 %) and water (50 %) for frost protection to –35 °C. l  “G12+” (60 %) and water (40 %) for frost protection to –40 °C. –  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 reservoir for cooling system charge unit -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 adapter -V.A.G 1274/8- on coolant expansion tank.

–  Open bleeder screw -arrow- in coolant hose at top left of radiator. –  Fill up with coolant until it flows out at bleeder hole. –  Close the bleeder screw.

–  If fitted, open bleeder screw -arrow- in coolant hose going to heat exchanger for heater. –  Fill up with coolant until it flows out at bleeder hole. –  Close the bleeder screw.

–  Check the coolant level and top up coolant as far as the max mark. –  On vehicles with auxiliary heater, switch auxiliary heater on (for about 30 seconds) → Owner's Manual. –  Start engine, run for 2 minutes (maximum) at approx. 2000 rpm and top up coolant to max. mark on expansion tank with engine running. –  Tighten filler cap on expansion tank. –  Run engine until radiator fan cuts in.   WARNING Hot steam or hot coolant can escape when expansion tank is opened; cover filler cap with cloth and open carefully. –  Check coolant level and top up if necessary. 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. –  Switch engine off.