how to tell if my cars thermostat is bad
When the car is hot, squeeze the upper radiator hose. If it feels soft, then the thermostat is not opening and therefore bad. If you squeeze the hose and its hard to squ â¦ eeze, then it is pressurized and the thermostat is open.That is one way to check if the thermostat is stuck closed.o test a thermostat remove it while the motor is cold and make sure it is not stuck open. If it is stuck open when cold it is faulty. If it it is closed put it in water on a â¦ stove with a thermometer and heat the water.