Can a car thermostat bust in cold weather?

Answer 1

Generally they don't "bust". They stick open or closed usually from wear. If the thermostat sticks open the engine is slow to warm up and gives you poor heat from the heater. If the thermostat sticks closed the engine overheats quickly and can cause serious damage. The weather doesn't have any effect on the thermostat however, if the there isn't sufficient antifreeze protection and the coolant freezes the engine will overheat quickly and can cause serious damage much like a stuck closed thermostat. Generally a 50/50 mix of clean water and antifreeze will protect the system to -34 degrees F. Have the coolant tested if your not sure.