Cooling System

Connection Diagram, Coolant Hoses


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.

• Secure all hose connections with hose clamps appropriate for the model. Refer to the electronic parts catalog ETKA.

• Arrows on coolant pipes and coolant hoses must line up across from each other.






1 Coolant Reservoir

• With sealing cap

• Pressure relief valve in cap, checking => [ Pressure Relief Valve in Cap,
Checking ] Testing and Inspection

2 Cylinder Head and Cylinder Block

• Change coolant after replacing

3 Cooler for Exhaust Gas Recirculation (EGR)

• Change coolant after replacing

• Removing and installing, refer to => [ Housing with EGR Cooler ] Housing With EGR Cooler

4 Auxiliary Heater

5 Recirculation Pump (V55)

6 Heater Core

• Change coolant after replacing

7 Transmission Oil Cooler

• For the dual clutch transmission

• Change coolant after replacing

8 Engine Oil Cooler

9 Engine Preheating Element (Z97)

• Removing and installing, refer to => [ Engine Preheating Element ] Service and Repair

10 Radiator

• Change coolant after replacing

11 4/2-Way Valve with Thermostat

• Removing and installing, refer to => [ 4/2-Way Valve with Thermostat ] 4/2-Way Valve with Thermostat

12 Coolant Pump

Coolant System Components - Intake Side






1 Lower Reservoir Coolant Hose

2 Upper Reservoir Coolant Hose

3 Bolt

• 10 Nm

4 Ventilation Pipe

5 Engine Coolant Temperature Sensor (G62)

6 Retaining Clip

7 O-ring

• Replace

8 Transmission Oil Cooler

• Only on vehicles with the dual clutch transmission

9 Engine Oil Cooler Coolant Supply Hose

• On vehicles without a transmission fluid cooler

• On vehicles with a transmission oil cooler: coolant hose return transmission fluid cooler

10 Engine Oil Cooler Coolant Return Hose

11 To the Upper Radiator

12 Bracket for Wiring Harness and Coolant Pipe

13 Coolant Hose

• To the coolant pipe on the cylinder block

14 Coolant Hoses

• For the transmission oil cooler

• Only on vehicles with the dual clutch transmission

• Installed depending on the vehicle equipment level

15 Coolant Line

• For the engine preheating element (Z97)

• Assembly overview

• Installed depending on the vehicle equipment level

16 Engine Preheating Element (Z97)

• Assembly overview

• Removing and installing, refer to => [ Engine Preheating Element ] Service and Repair

• Installed depending on the vehicle equipment level

17 Engine Oil Cooler

18 Coolant Thermostat

• Checking coolant regulator, refer to => [ Thermostat, Checking ] Testing and Inspection

19 Connecting Piece

20 Bolt

• 15 Nm

21 Hose to the Lower Radiator

22 Coolant Pump

23 Bolt

• 40 Nm

Engine Preheating Element (Z97) Assembly Overview






1 Coolant Pipe for the Engine Preheating Element (Z97)

2 Coolant Hose from the Cylinder Block Connection to the Transmission Oil Cooler

3 Coolant Hose from the Transmission Oil Cooler to the Engine Oil Cooler

4 Coolant Hose from he Engine Pre-Warmer Coolant Pipe, to the Engine Preheating Element (Z97)

5 Retainer

6 External Power Supply Connecting Wire

7 Left Air Intake Grille

- Air Intake Grille, Removing and Installing.

8 Bracket

9 Engine Preheating Element (Z97)

• Removing and installing, refer to => [ Engine Preheating Element ] Service and Repair

10 Engine Preheating Element (Z97) Clamp

• Secured on the bracket

11 Bolt

• 10 Nm

12 Engine Preheating Element (Z97) Bracket

13 Bracket for Wiring Harness and Coolant Pipe

14 Coolant Hose from the Oil Cooler to the Engine Preheating Element (Z97) Coolant Pipe

15 Engine Preheating Element (Z97) Coolant Hose to the Coolant Pipe on the Cylinder Block

Cooling System Components - Transmission Side






1 Coolant Supply Hose

2 Coolant Hose to the Ventilation Pipe

3 Exhaust Gas Recirculation Cooler Coolant Return Hose

4 Coolant Return Hose

5 Heat Exchanger Coolant Supply Hose

6 Heat Exchanger Coolant Return Hose

7 Exhaust Gas Recirculation Cooler Coolant Supply Hose

8 Transmission Oil Cooler Coolant Supply Hose

9 Transmission Oil Cooler

10 Transmission Oil Cooler Coolant Return Line