Is it necessary to drain all the antifreeze when changing the thermostat on a truck?

It depends on where the thermostat is located. You only need to drain it so that the antifreeze is lower than the thermostat. (usually less than half)


If you don%26#039;t drain it , it will only run out.|||I usually recommend changing the antifreeze when changing the thermostat unless the coolant has recently been changed.It depends on the age and condition of the antifreeze, generally most people do not change a thermostat until age and corrosion have destroyed it and the antifreeze is usually well past it%26#039;s useful life and yes should be drained and flushed at the same time. Coolant does age and breakdown and should be replaced on average after about 3-4 years of service. You can test your antifreeze with a litmus strip (measures the acidity of the antifreeze), as the coolant breaks down it turns acidic and is hard on the heater core, radiator and water pump seal, not only that but an acid flowing through metal builds up a static charge and that charge has to dissipate by arcing to the metal causing pitting and corrosion.|||depends on where its located the higher the location of the thermostat the less you need to drain the lower the location of the thermostat yes drain the radiator and when i say higher i mean in relation to the radiator and fill tank|||if it has come time to change the coolant thermostat, then yes it is advisable to change out all the coolant.