2000 A8 40V Thermostat Replacement Without Removing T-Belt

My brother in-law’s A8 has an overheating problem after the “quick fix” of the oil cooler pipe leaks- He poured the radiator leaks sealer into the coolant in the attempt to seal the leaks-The thermostat stops opening, stuck close. We don’t know if the thermorstat ceased to open on its own or with the help …