So i replaced my thermostat and whenever i run the car for about 30min the temperature starts rising and then drops out of nowhere and it goes back to normal, how come?
So i replaced my thermostat and whenever i run the car for about 30min the temperature starts rising and then drops out of nowhere and it goes back to normal, how come?
Did you bleed the cooling system after replacing the thermostat? There's a specific heat capacity for everything we know. The specific heat capacity of air is a lot different than water (if they both had the same specific heat capacity, we would freeze when it gets below freezing). Air's specific heat capacity is MUCH less than coolant. The temperature of the coolant determines whether or not the thermostat opens, not air (there's a spring that's forced open when the coolant reaches a certain temperature). If you want cool science experiment, stick a thermostat in boiling water and it will open. Stick the same thermostat in cold water and it will close. Run the heat and stick the thermostat up against the register, it remains closed, despite the heat.
the temperature starts rising and then drops out of nowhere and it goes back to normal
The temperature should go up until the engine reaches operating temperature then level off and stay there. It should not go higher and then come back down. If you're noticing a fluctuation as I just described, then you likely have either air in your cooling system (as described by @justin-shepherd) or you could have a bad (new)thermostat.
Members can be more helpful if you include your year, make, model, transmission type & mileage.
that's the thermostat opening. The hot coolant starts flowing through the radiator and is cooled down. That's what it's for.
