[SpudRider]

Coolant Overflow Bottle

When the radiator cap vents coolant to reduce system pressure in the engine cooling system, the coolant is collected in the overflow bottle. When engine heat is reduced and system pressure decreases, the coolant in the overflow bottle is returned to the radiators.

The coolant overflow bottle has markings for minimum and maximum levels of coolant. When the engine is cold, the coolant level in the overflow bottle should reach the minimum mark. When the engine is hot, the coolant level in the overflow bottle should reach the maximum mark.

If the coolant level falls below the minimum mark when the engine is cold, you should add more coolant until the level reaches the minimum mark. Maintaining the minimum level of coolant will prevent air voids from forming in the cooling system.