Is It Normal for the Expansion Tank to Have No Water?

[VonMadison]

It is not normal for the expansion tank to have no water. If the pipes connecting the main radiator and the expansion tank, as well as the radiator cap, are functioning properly, the main radiator will draw water from the expansion tank when it runs low. The expansion tank should maintain about half of its coolant capacity—having no water at all is unacceptable. Common reasons for frequent coolant loss in the expansion tank include: 1. A damaged cylinder head gasket; 2. Leaking hoses; 3. Radiator leaks or faulty valves; 4. Heater core leaks; 5. Leaking core plugs. The expansion tank is a critical part of the engine cooling system, helping to balance radiator pressure. When the engine temperature rises, the coolant expands, and some antifreeze flows into the expansion tank through the radiator cap. Conversely, when the temperature drops and the cooling system pressure becomes negative, the system draws antifreeze back from the expansion tank into the cooling system via the radiator cap.