Thread: Faulty Thermostat

How do we know whether the thermostat on Td5 is faulty or not without taking it out??

I had a faulty new thermostat.
Check ends of radiator. If the motor is fully warmed up, than both ends should be warm as well. If the water is not flowing through the radiator, the passenger side will be warm/hot, but the drivers side will be quite cold, indicating that the thermostat may not be opening.
Peter.