Overflow Bottle : An overflow bottle is used by the radiator to hold extra coolant for the radiator. When the pressure increases past the radiator cap limit, the excess pressure is collected in the overflow bottle. When the coolant within the radiator runs low, the radiator will take in the coolant to refill it up again. This process happens while driving. When the overflow bottle is low, you must top it off again with coolant. If the overflow bottle runs low frequently, this is often an indication of a cooling system problem such as a coolant leak.
Overflow bottles generally do not go bad often. Occasionally though, they may get old and spring a leak. If the overflow bottle leaks, it should be replaced.
Guy’s Automotive repairs all types of coolant leaks and more. Checkout our cooling systems service page or just bring it in for an inspection.