Engine Side, Overview

Cooling system components (engine side), overview

Note: An additional electric pump for continued coolant circulation (After-run coolant pump -V51-) is installed in vehicles in hot countries. Fitting position and function, Fig. 1






1. Connection
For thermostat

2. O-ring
Always replace

3. Coolant thermostat
Removing and installing, refer to Thermostat, Engine Cooling - Service and Repair - Procedures Service and Repair
Observe installation position
Checking: heat-up thermostat in water
Opening commences approximately 86° C
Opening lift min. 7 mm

4. Breather bolt, 20 Nm
5. 25 Nm

6. Retaining clip
Check seated securely

7. Coolant - temperature sender (G62)
For engine control module
If necessary release pressure in cooling system before removing
Checking, refer to Displaying and Reading Trouble Codes at Powertrain Management - Computers and Control Systems - Testing and Inspection - Procedures Testing and Inspection

8. Rear coolant hose
Coolant hose connection diagram, refer to Coolant Line/Hose - Diagrams - Mechanical Diagrams

9. Lifting eye

10. 10 Nm
Also note item 23

11. Coolant hose
Coolant hose connection diagram, refer to Coolant Line/Hose - Diagrams - Mechanical Diagrams

12. Front coolant hose
Coolant hose connection diagram, refer to Coolant Line/Hose - Diagrams - Mechanical Diagrams

13. Cap
Check with cooling system tester VAG 1274 and adapter VAG 1274/9
Test pressure: 1.4 - 1.6 bar

14. O-ring
Replace if damaged

15. Expansion tank
Carry out leakage test of cooling system with cooling system tester VAG 1274 and adapter VAG 1274/8

16. Upper coolant hose
Secured to radiator with retaining clip
Check securely seated
Coolant hose connection diagram, refer to Radiator Hose - Diagrams - Mechanical Diagrams

17. Coolant hose
Coolant hose connection diagram, refer to Coolant Line/Hose - Diagrams - Mechanical Diagrams

18. Rear toothed belt guard

19. Gasket
Always replace

20. Coolant pump
Check for ease of movement
If damaged or leaking replace complete
Removing and installing, refer to Water Pump - Service and Repair - Procedures Service and Repair

21. Lower coolant hose
Coolant hose connection diagram, refer to Coolant Line/Hose - Diagrams - Mechanical Diagrams

22. Oil cooler

23. Belt pulley
For viscous fan coupling
Tightening torque for 3 securing bolts 30 Nm

24. Radiator fan

25. Viscous fan coupling
Observe left hand thread
Tightening torque only valid for open jaw spanner 3312
Tighten to 40 Nm
Removing and installing, refer to Cooling Fan, Radiator - Fan Clutch - Service and Repair - Procedures Service and Repair

26. Bracket
For viscous fan coupling

27. From bottom of radiator
Coolant hose connection diagram, refer to Radiator Hose - Diagrams - Mechanical Diagrams

Fig. 1 After-run coolant pump -V51-






The after-run coolant circulation pump -arrows- is generally activated for 10 - 12 minutes about 15 seconds after ignition is shut off. If the coolant temperature is above 92 C, the radiator fan -V7- will also be turned on.

Special tools and equipment

- Hand multimeter VAG 1526 or multimeter VAG 1715
- Wiring diagram

Check conditions





- Fuse 34 must be OK.

Test sequence
- Start engine and idle briefly.
- Switch ignition off.
Continued coolant circulation pump (V51) must start after about 15 seconds.
If pump does not run:
- Pull 2-pin connector off pump.
- Attach multimeter for measuring voltage to contacts 1+2 of connector.
Specification: 11 - 15V
If the specification is obtained:
- Replace continued coolant circulation pump.
If no voltage is present:
- Check wiring from relay plate to continued coolant circulation pump.