When to replace the Thermostat on your AUDI A6
Recommended replacement interval for the part category Engine thermostat : 50000 km
Important!
This replacement procedure can be used for:
AUDI A6 Avant (4B5, C5) 1.8, AUDI A6 Avant (4B5, C5) 1.8 T, AUDI A6 Avant (4B5, C5) 1.8 T quattro, AUDI A6 Avant (4B5, C5) 1.8 T quattro, AUDI A6 Avant (4B5, C5) 1.8 T, AUDI A6 Avant (4B5, C5) 1.8 View more

The steps may slightly vary depending on the car design.

This video shows the replacement procedure of a similar car part on another vehicle

Tools
Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Tools you might need:
Wire brush
All-purpose cleaning spray
Electronic spray
Sealant
Torque wrench
Combination spanner #10
Combination spanner #13
Combination spanner #17
Combination spanner #46
Drive socket # 10
Drive socket # 13
HEX bit No.H5
HEX bit No.H8
Ratchet wrench
Funnel
Fluid container
Pincers
Fender cover
Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). AUTODOC experts recommend:
  • Check the condition of the coolant every time you replace the thermostat. Change the coolant if necessary.
  • All work should be done with the engine stopped.
Carry out replacement in the following order:
  1. Step 1
    Open the hood.
    Step 2
    Use a fender protection cover to prevent damaging paintwork and plastic parts of the car.
    Step 3
    How to change Thermostat on Audi A6 C5 Avant 1997 - free PDF and video manuals
    Unscrew the engine cover fastener. Use HEX No.H5. Use a ratchet wrench.
  2. Step 4
    How to replace AUDI A6 Avant (4B5, C5) 2.5 TDI quattro 1998 Thermostat - step-by-step manuals and video guides
    Remove the engine cover.
    AUTODOC recommends:
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Do not use excessive force when removing the part as this may damage it.
  3. Step 5
    Audi A6 C5 Avant 1.9 TDI 1999 Thermostat replacement: free workshop manuals
    Unscrew the coolant reservoir cap.
  4. Step 6
    Changing Thermostat on AUDI A6 Avant (4B5, C5) 2.5 TDI 2000 by yourself
    Prepare a container for fluids.
  5. Step 7
    How to remove AUDI A6 1.8 T 2001 Thermostat - online easy-to-follow instructions
    Clean the coolant hose. Use all-purpose cleaning spray.
  6. Step 8
    How to replace Thermostat on AUDI A6 Avant (4B5, C5) 2002: download PDF manuals and video instructions
    Disconnect the coolant pipe retaining clip.
  7. Step 9
    How hard is it to do yourself: Thermostat replacement on Audi A6 C5 Avant 1.8 T quattro 2003 - download illustrated guide
    Detach the coolant hose.
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Professionals recommend:
    Caution! Coolant may leak out of the coolant lines and thermostat housing.
  8. Step 10
    Need to know how to renew Thermostat on AUDI A6 2004? This free workshop manual will help you to do it yourself
    Drain the coolant from the engine.
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Tip:
    Caution! The coolant can be very hot.Wear gloves to prevent contact with hot liquid.All work should be done with the engine stopped.Wait until the coolant has completely flowed out of the drain hole.
  9. Step 11
    Changing of Thermostat on Audi A6 C5 Avant 2005 won't be an issue if you follow this illustrated step-by-step guide
    Clean the coolant hose. Use all-purpose cleaning spray.
  10. Step 12
    AUDI A6 1.9 TDI Thermostat replacement: online guides and video tutorials
    Attach the coolant hose.
  11. Step 13
    Connect the coolant pipe retaining clip.
    Step 14
    Replacing Thermostat on Audi A6 C5 Avant 1998 2.5 TDI quattro by yourself
    Clean the coolant hose. Use all-purpose cleaning spray.
  12. Step 15
    A6 Avant (4B5, C5) 1.8 T 1999 Thermostat DIY replacement workshop manual
    Pull aside the V-ribbed belt tensioner pulley. Use a combination spanner #17.
  13. Step 16
    How to change Thermostat on AUDI A6 Avant (4B5, C5) 2000 - tips and tricks
    Remove the V-ribbed belt.
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Tip from AUTODOC:
    Check the condition of the tensioner pulley and idler pulley. Replace them if necessary.
  14. Step 17
    Step-by-step recommendations for DIY replacement Audi A6 C5 Avant 2001 1.8 T Thermostat
    Return the tensioner pulley to its initial position.
  15. Step 18
    DIY replacement of Thermostat on AUDI A6 Avant (4B5, C5) 2.4 2002 is not an issue anymore with our step-by-step tutorial
    Remove the battery cover.
  16. Step 19
    How to change Thermostat on Audi A6 C5 Avant 1997 - free PDF and video manuals
    Unscrew the fasteners of the car battery terminals. Use a combination spanner #10.
  17. Step 20
    How to replace AUDI A6 Avant (4B5, C5) 2.5 TDI quattro 1998 Thermostat - step-by-step manuals and video guides
    Remove the battery terminals.
  18. Step 21
    Audi A6 C5 Avant 1.9 TDI 1999 Thermostat replacement: free workshop manuals
    Loosen the alternator fasteners. Use HEX No.H8.
  19. Step 22
    Changing Thermostat on AUDI A6 Avant (4B5, C5) 2.5 TDI 2000 by yourself
    Unscrew the fastener of the viscous fan clutch. Use a combination spanner #46. Use HEX No.H8.
  20. Step 23
    How to remove AUDI A6 1.8 T 2001 Thermostat - online easy-to-follow instructions
    Loosen the alternator fasteners. Use HEX No.H8.
  21. Step 24
    How to replace Thermostat on AUDI A6 Avant (4B5, C5) 2002: download PDF manuals and video instructions
    Remove the alternator.
  22. Step 25
    How hard is it to do yourself: Thermostat replacement on Audi A6 C5 Avant 1.8 T quattro 2003 - download illustrated guide
    Disconnect the alternator connector.
  23. Step 26
    Need to know how to renew Thermostat on AUDI A6 2004? This free workshop manual will help you to do it yourself
    Unscrew the alternator power cable fastener. Use a combination spanner #13.
  24. Step 27
    Changing of Thermostat on Audi A6 C5 Avant 2005 won't be an issue if you follow this illustrated step-by-step guide
    Clean the thermostat housing. Use all-purpose cleaning spray.
  25. Step 28
    AUDI A6 1.9 TDI Thermostat replacement: online guides and video tutorials
    Unscrew the thermostat housing fasteners. Use a drive socket #10. Use a ratchet wrench.
  26. Step 29
    Replacing Thermostat on Audi A6 C5 Avant 1998 2.5 TDI quattro by yourself
    Remove the thermostat housing.
    AUTODOC recommends:
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Do not use excessive force when removing the part as this may damage it.
  27. Step 30
    A6 Avant (4B5, C5) 1.8 T 1999 Thermostat DIY replacement workshop manual
    Remove the thermostat. Use pincers.
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Tip:
    Do not apply excessive force when removing the part. Otherwise you may damage it.Caution! Coolant may leak out of the coolant lines and thermostat housing.
  28. Step 31
    How to change Thermostat on AUDI A6 Avant (4B5, C5) 2000 - tips and tricks
    Clean the thermostat housing mounting seat. Use a wire brush. Use all-purpose cleaning spray.
  29. Step 32
    Install a new thermostat.
    AUTODOC recommends:
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Do not use excessive force during installation. This may damage the part.
    Step 33
    Step-by-step recommendations for DIY replacement Audi A6 C5 Avant 2001 1.8 T Thermostat
    Treat the thermostat housing. Use a sealant.
  30. Step 34
    DIY replacement of Thermostat on AUDI A6 Avant (4B5, C5) 2.4 2002 is not an issue anymore with our step-by-step tutorial
    Install the thermostat housing.
    Replacement: engine thermostat – AUDI A6 Avant (4B5, C5). Tip from AUTODOC:
    When installing, do not use excessive force to avoid damage to the part.
  31. Step 35
    How to change Thermostat on Audi A6 C5 Avant 1997 - free PDF and video manuals
    Tighten the thermostat housing fasteners. Use a drive socket #10. Use a torque wrench. Tighten it to 6 nm torque.
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DIY AUDI A6 Avant (4B5, C5) Thermostat replacement - online guide
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