Note: If the drained coolant is to be reused, use a clean container to collect the coolant.
1. Remove the expansion tank cap.
4. On models with a drain plug, unscrew the plug (see illustration 17.4 Chapter 2) drain hole on the coolant hose (bottom left) and drain the coolant into a previously prepared container. Tighten the drain plug.
5. On models without a drain plug, remove the retainer (1 in illustration 5.7 Chapter 2) coolant temperature sensor (2) at the radiator outlet, pull the sensor out of the hose connection and drain the coolant into a previously prepared container.
6. On 1.6, 1.8, 2.0 MPI and 3.0 L petrol engines and on 4-cylinder diesel engines, remove the decorative engine cover (see Chapter 2), unscrew the screw (arrow in illustration 5.23 Chapter 2) expansion tank mounts, disconnect the K/L low coolant level sensor connector on the underside of the expansion tank and move the tank to the side without disconnecting the hoses from it. Disconnect the hose from the oil cooler (arrow in the illustration5.24 or 29.13 Chapter 2) and allow the remaining coolant to drain. Reconnect the hose and replace the expansion tank and engine cover.
7. On 3.2L engines, disconnect the hoses from the oil cooler to drain the coolant (see illustration 2.7a), and then disconnect the lower hose from the radiator (see illustration 2.7b). Connect the hoses. Use a new sealing ring for the lower radiator hose.
2.7a. Hose on the oil cooler of the 3.2 l engine
2.7b. Lower radiator hose retainer
8. On 4.2 L engines, to drain the coolant, unscrew the plug in the thermostat housing (see illustration). When tightening the plug, use a new O-ring.
2.8. Drain plug on the thermostat of the 4.2L engine (S4)
9. On 6-cylinder diesel models, to drain the coolant, disconnect the hoses shown in the illustrations, as well as the lower radiator hose (see illustration 2.7b). Connect the hoses. Use a new sealing ring for the lower radiator hose.
2.9a. Connecting the hose and tube (6-cylinder diesel models)
2.9b. Coolant hoses behind the engine (6-cylinder diesel models)
10. Fill the coolant into the reservoir of the VAS6096 cooling system filling device (see illustration). Screw the adapter VAG1274/8 onto the expansion tank instead of the cap, and install the VAS6096 device onto it. Lower the purge hose (1) into a small container (2) to collect the coolant coming out with the air. Close both valves (A and B) and connect the hose (3) to a source of compressed air with a pressure of 6+10 bar.
2.10. Device for filling the cooling system
11. Open the valve (In illustration 2.10), - a vacuum will be created in the cooling system and the pointer on the pressure gauge should move into the green zone. Open valve (A) so that the hose of the VAS6096 tool is filled with coolant and immediately close valve (A). After 2 minutes, during which time a vacuum should be created in the cooling system again and the pointer on the pressure gauge should move into the green zone again, close valve (B). If the pointer on the pressure gauge does not reach the green zone, repeat the procedure from the beginning. If the vacuum drops with the valve closed, check the cooling system for leaks.
12. Disconnect the hose (3 in illustration 2.10) from the compressed air source and open the valve (A), - the coolant from the tank of the VAS6096 device will flow into the cooling system.
13. Disconnect the VAS6096 tool from the VAG1274/8 adapter and install the VAG1274/10 tube in its place (see illustration)
2.13. Tube on the expansion tank
14. On 1.6, 1.8, 2.0 MPI and 3.0L models, as well as on 6-cylinder diesel models, remove the screw (see illustrations) bleed and fill the expansion tank so that the coolant starts to come out through the opened hole. Screw in the screw.
Note: On the 3.0L engine, remove the front of the engine cover to access the screw.
2.14a. Bleed screw on petrol models 1.6, 1.8 and 2.0 MPI
2.14b. Bleed screw on petrol models 3.0 MPI
2.14s. Bleed screw on 6-cylinder diesel models
15. Loosen the hose going to the air conditioning radiator and pull this hose away from the pipe enough to open the bleeding hole (see illustration). Fill the expansion tank so that the coolant starts to come out through this hole without bubbles, install the hose in place and secure it.
Note: On some models, the windshield cowl cover must be removed to access the hose (see Section 15 Chapter 1).
2.15. Air bleed hole on the heater hose
15. On models with additional heating, turn it on for about 30 seconds and close the expansion tank cap.
16. Start the engine, set the maximum temperature of the climate system for both zones and let the engine run for about 3 minutes at 2000 rpm. Then let the engine run at idle speed until both radiator hoses are warm. Finally, let the engine run for one minute at 2000 rpm, turn off the ignition and let the engine cool down.
17. Check and, if necessary, adjust the coolant level (see Section 4 Chapter 1).
(The article is a reprint of material from «AudiManual»)