Why is my coolant overflow tank empty?

Your Engine’s Cylinder Head Gasket is blown. This is causing the engine to consume/burn the coolant. This is the reason your coolant auxiliary tank is always empty. The boiling out of water also happens due to this.

Should there be fluid in the radiator overflow?

This small reservoir on the side of the radiator collects any fluid that spills out when the radiator overflows. Tip: Most overflow tanks have a way to move the coolant they contain back into the cooling system, so it is a good idea to add the radiator fluid to this overflow tank rather than directly into the radiator.

Should there be coolant in the overflow when cold?

If you notice coolant level low when cold, you have to too up the coolant. Or notice the car running hot, you have to turn off your engine. It will take your engine one to two hours to cool down. Once your engine is cool, open your radiator and overflow tank, top your overflow tank till it gets to the full level.

How does the radiator overflow reservoir work?

The radiator coolant overflow tank works by filling the tank with coolant when the cooling system’s pressure is too high and withdraw coolant from it when there is under pressure in the system. The coolant is transferred back and forth between the tank and cooling system depending on the pressure.

Should I put coolant in my radiator or reservoir?

If your engine is cold, the coolant level should be up to the cold fill line. If the coolant level is low, add the correct coolant to the reservoir (not the radiator itself). You can use diluted coolant by itself, or a 50/50 mixture of concentrated coolant and distilled water.

Why is my coolant boiling in the overflow?

When there’s a leak in the cooling system, the pressure of the liquid drops and so does the boiling point of the coolant/antifreeze. Cooling systems are pressurised to raise the boiling point of the fluid, with the pressure cap and the overflow helping to raise the temperature at which the coolant/antifreeze boils.