Cooling System: Service and Repair
Cooling System, Draining and Filling
Special tools, testers and auxiliary items required
• Adapter (V.A.G 1274/8)
• Drip Tray for Workshop Crane (VAS 6208)
• Cooling System Charge Unit (VAS 6096)
• Hose Clamp Pliers (VAS 6362)
• Refractometer (T10007)
Draining
- On a vehicle with air suspension, activate vehicle lift mode.
• Drained coolant must be stored in a clean container for disposal or reuse.
Risk of scalding due to hot steam and hot coolant.
• When the engine is warm the cooling system is under pressure.
• To reduce pressure, cover coolant reservoir cap with cloth and carefully open.
- Remove screws and remove front noise insulation - 1 -.
- Place (VAS 6208) under engine.
- Remove drain plug - 1 - on map controlled engine cooling thermostat (F265) and allow coolant to drain.
• Ignore - 2 -.
- Remove drain plug - arrow - at front coolant pipe and drain coolant.
- Lift the clamp to remove the lower coolant hose - arrow - and let the coolant drain.
- Remove coolant hoses from coolant pipes - arrows - and drain remaining coolant.
Filling
• Tightening specifications, refer to => [ Coolant Pump and Coolant Thermostat Assembly Overview ] Coolant Pump and Coolant Thermostat Assembly Overview, => [ Coolant Pipes Assembly Overview ] Coolant Pipes Assembly Overview.
• Ignition switched off.
• The cooling system is filled all year round with a mixture of frost and corrosion protection additives and water.
• Only use one of the frost and corrosion additives approved for this vehicle. Other coolant additives may above all reduce the corrosion protection effect significantly. The damage resulting from this may lead to loss of coolant and consequently to severe engine damage.
• Frost and corrosion protection additives prevent freezing and corrosion damage and scaling. They also raise the boiling point. For this reason the system must be filled all year round with frost and corrosion protection additives.
• Because of its high boiling point, the coolant improves engine reliability under heavy loads, particularly in countries with tropical climates.
• Protection against frost must be assured to about -25 °C / -77 °F (in arctic climatic countries to about -35 °C / -95 °F).
• The coolant concentration must not be reduced by adding water even in warmer seasons and in warmer countries. The coolant additive portion must be at least 40%.
• If increased freeze protection is needed because of the climate, the amount of G12+ can be increased, but only up to 60% to provide freeze protection to about -40 °C / -104 °F. Otherwise the freeze protection and cooling effectiveness will be reduced.
• Only use clean drinking water for mixing coolant.
• Do not use drained coolant in the following situations:
• If the radiator, heat exchanger, cylinder head or cylinder head seal or cylinder block were replaced.
• If the coolant is contaminated.
• Secure all hose connections with hose clamps appropriate for the model.
• Use the (T10007) to determine the level of freeze protection in the coolant system.
- Install drain plug - 1 - with new O-ring on map controlled engine cooling thermostat (F265).
• Ignore - 2 -.
- Reinstall drain plug - arrow - with new gasket at front coolant pipe.
- Remove the coolant hose on the bottom right of the radiator. Refer to => [ Connect the Coolant Hose with the Connector
Coupling ] Radiator Assembly Overview.
- Install coolant hoses at coolant pipes - arrows -.
- Fill coolant reservoir of (VAS 6096) with at least 12 liters of pre-mixed coolant with correct mixture ratio:
• Coolant freeze and corrosion protection additive (40%) and water (60%) for freeze protection down to -25 °C / -77 °F.
• Coolant freeze and corrosion protection additive (50%) and water (50%) for freeze protection down to -35 °C / -95 °F.
• Coolant freeze and corrosion protection additive (60%) and water (40%) for freeze protection down to -40 °C / -104 °F.
• For coolant freeze and corrosion protection additive.
- Attach (V.A.G 1274/8) to coolant expansion tank.
- Install (VAS 6096) on (V.A.G 1274/8).
- Place air outlet hose - 1 - into a small container - 2 -. (A small amount of coolant is drawn off which should be reserved with the discharged air.)
- Close both valves - A - and - B - by turning lever perpendicular to direction of flow.
- Connect hose - 3 - to pressurized air.
• Pressure: 6 to 10 bar pressure.
- Open valve - B -, turn lever in direction of flow to do this.
A vacuum is created in the cooling system by the suction jet pump.
• Needle on the instrument display must travel into the green region.
- Also briefly open valve - A - by turning lever in direction of flow so that (VAS 6096) coolant reservoir hose is filled with coolant.
- Close valve - A - again.
- Let valve - B - remain open another 2 minutes.
• A further vacuum is created in the cooling system by the suction jet pump.
• Needle on the instrument display must still remain in the green region.
- Close valve - B -.
• Needle in the display instrument must remain in the green region, then the sufficient vacuum in the cooling system is obtained for the upcoming filling.
If needle stands below the green region, repeat procedure.
If the vacuum decreases, cooling system is leaking.
- Disconnect pressurized air hose.
- Open valve - A -.
The vacuum in the cooling system has the effect of extracting coolant from replacement reservoir (VAS 6096/1); cooling system is filled.
- Detach (VAS 6096) from (V.A.G 1274/8) on coolant expansion tank.
- If the vehicle has an auxiliary heater, switch it on for about 30 seconds.
- Twist expansion tank cap closed.
- Start engine.
- Set the temperature to "HI" for all zones and set the fan speed as low as possible (0).
- Switch the A/C compressor off by pressing the ECON/ON/OFF button.
- Let engine run at 2000 RPM for 3 minutes.
- Let engine run at idle long enough until both large coolant hoses on main cooler are warm.
- Let engine run at 2000 RPM for 1 minute.
- Turn off engine and allow it to cool off.
- Check coolant level.
• Coolant level must be at MAX-marking - arrow - with engine cold.
• Coolant level may be above MAX marking with engine at operating temperature.
- On a vehicle with air suspension, deactivate vehicle lift mode.