Checking the thermostat (Audi 100 C3)

Depending on the ambient temperature or vacuum, the thermostat controls the flow of warm or cold air supplied to the carburetor. Damage to the thermostat will lead to interruptions when increasing the crankshaft speed of an unheated engine, increased fuel consumption and freezing of the engine intake pipe. Check the thermostat on a cold engine. Damper (see Fig. Air filter) should turn freely, without jamming.

Execution order

1. Loosen the clamp and remove the hose from the thermostat pipe. Check the position of the damper. The warm air supply opening must be closed.

2. Remove the filter from the carburetor (see subsection 6.1.2).

3. Connect the hose to the carburetor by placing it on the branch pipe instead of the hose.

4. Start the engine and let it idle. The flap should turn and allow warm air to enter.

5. Disconnect the hose from the carburetor. The flap should turn and block the access of warm air. If this does not happen, replace the thermostat.