Where is the Audi 2.4 thermostat located?

[VanFinn]

Audi A6 2.4L thermostat is installed inside the engine coolant return pipe joint. Function of thermostat: The vehicle thermostat protects engine operation by preventing cylinder explosion caused by excessive temperature during operation. If the vehicle lacks a thermostat, it will affect driving performance and may even lead to engine failure in severe cases. Thermostat condition detection: You can judge by feeling the temperature difference between upper and lower radiator hoses. Start the engine and touch both hoses after 3 minutes. A functional thermostat will show temperature difference - typically the upper hose is hot while the lower hose remains cool. When engine coolant reaches 90°C, both hoses should become hot, indicating a good thermostat. If both hoses maintain the same temperature immediately after starting, the thermostat is faulty.