Does coolant level change with temperature?
Does coolant level change with temperature? The coolant inside a car's cooling system drastically fluctuates in temperature, which means its volume also changes. Once the radiator is completely full, this expanding hot coolant will overflow into the reservoir. When the coolant cools back down it contracts, which creates a vacuum. Should coolant be low when engine is hot? The coolant level should be at the tank's MAX or HOT line when the engine is hot, and lower when it's cold. Yes. Draining out the coolant and refilling the system removes dirt and rust particles that can clog up the cooling...