Audi A6 C6: How to Replace Thermostat

Keeping the temperature in check is important for your engine. Your thermostat is needed to keep your engine running smoothly. Engine thermostats are important to keep your engine from getting hot.

By Jack Plageman - May 9, 2016

This article applies to the Audi A6 C6 (2004-2011).

The coolant in your car keeps your engine from overheating and breaking down. Your car uses a thermostat to control the temperature of the coolant moving throughout your engine. The thermostat regulates the flow of coolant through the radiator to keep the engine running cool. If the thermostat fails, your car might overheat as the coolant flow is restricted. If you notice a sensor come on or if your temperature gauge is starting to act differently than normal, your engine is overheating and it is time to change your car's thermostat.

Audi A6 C6: How to Replace Thermostat

Materials Needed

  • Socket and ratchet set (you'll need multiple sizes)
  • Bucket/catch pan
  • Pin wrench 3212
  • Gloves
  • Hose clamps

Note: it is recommended the you document the job as you go to ensure proper re-installation of parts.

Step 1 – Remove the coolant from your engine

Locate the reservoir cap on the engine and remove it. Then locate the drain cock for the coolant underneath the engine on the left side of the car. Place the bucket underneath and let the coolant drain out. Once the coolant has drained out, flush the system with warm water and drain. Use the hose clamps to clamp the hoses attached to the supercharger, so you do not get any leaking out when you take it out.

audi a6 a6 supercharger removal coolant radiator thermostat water pump replace remove how to change
Figure 1. Drain cock underneath the radiator.

Pro Tip

You can either save the coolant and put it back it the engine at the end, or you can replace it using G13 coolant.

Step 2 – Remove the supercharger

First take off the poly V belts from the supercharger, and always make sure you know which side the belt was facing before you put it back. Next, find the vacuum hoses attached to the supercharger and disconnect them. After, locate the six bolts on top and remove them. Once you've done that, you can carefully take the supercharger off the engine.

audi a6 a6 supercharger removal coolant radiator thermostat water pump replace remove how to change

Figure 2. This diagram shows you what parts make up the supercharger.


You do not need to remove every piece shown in the diagram. Just the ones keeping the supercharger attached to the engine.

(Related Thread: How to Remove Intake Manifold - AudiWorld)

Step 3 – Finding the thermostat

Once you have removed the supercharger from the engine, you will need to find where the housing for the thermostat is. It can be found near the front of the engine underneath the coolant crossover pipe. You will now need to remove the coolant pipe, using the pin wrench, to get into the thermostat housing.

audi a6 a6 supercharger removal coolant radiator thermostat water pump replace remove how to change
Figure 3. Thermostat location.

Pro Tip

Once you have removed the cover for the thermometer housing, you will notice a pink liquid. That is coolant that the thermometer gets its reading from.

Step 4 – Installing the thermostat

After you have taken off the housing to the thermostat you can now replace the old one with the new part. Reattach the the gasket, housing and coolant pipes, and then follow the previous steps in reverse to reattach the supercharger. Ensure that the supercharger is reinstalled carefully, as misalignment will cause issues with the drive belt.

audi a6 a6 supercharger removal coolant radiator thermostat water pump replace remove how to change
Figure 4. At the top of the image is the new thermostat piece that goes into the engine.

Pro Tip

Make sure you are properly reattaching the parts. If you do not, it could result in a failure of the thermostat or supercharger, which may damage your engine.

Step 5 – Replace your engine coolant

Once you have successfully reattached your thermometer and supercharger you can change out your coolant. It is recommended you use G13 coolant, which can be purchased online. To replace the coolant, drain the system again to make sure there is no residual fluid in the engine. Then flush with hot water and warm your car up for a few minutes, with the heat on high and the fans on low. Then drain the water out and add straight G13 to the coolant reservoir to get close to a 50/50 mixture of water and coolant.

Pro Tip

When warming your car, keep it around 2,000 rpms and you can stop when you feel warm air coming out of your air vents. It may take a few drains before the system is completely diluted of coolant.

Featured Video: How to Replace Thermostat and Water Pump

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