The 1.8 liter engine thermostat is located on the lower right hand side of the front of the engine. You can follow the top radiator hose directly to the thermostat housing.
The thermostat on a 1998 2.4 Audi a6 is located on the radiator under the top hose assembly. To access it, you will have to partially drain the radiator.
between the bumpers
You have to take off the front end of the engine, as if you were replacing the timing belt and water pump, huge effort for a thermostat.
If this is a 2.8 V6 the thermostat is located on the front of the engine. Ask 'Where is the thermostat located on a 1995 Audi A6?' on this site and you'll find someone has done a great job of explaining how to find and replace the thermostat.
Where is the electric radiator fan relay switch for a 2001 Audi A6 2.7t
18 Gallons
To change the thermostat on an Audi A6 2.7 Quattro, first ensure the engine is cool and disconnect the negative battery terminal. Drain the coolant from the radiator, then remove the upper intake manifold or any components obstructing access to the thermostat housing. Unbolt the thermostat housing, replace the old thermostat with a new one, and reassemble everything, making sure to refill the coolant and bleed the system for air pockets. Finally, reconnect the battery and check for leaks.
Low on coolant. Stuck open thermostat. Partially blocked heater core.
The EPA mileage estimate for the 2006 Audi A6 is 18 mpg in the city, 27 mpg on the highway.
The EPA mileage estimate for the 2009 Audi A6 is 18 mpg in the city, 27 mpg on the highway.
The EPA mileage estimate for the 2004 Audi A6 is 18 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2008 Audi A6 is 18 mpg in the city, 27 mpg on the highway.