What could cause the coolant to overflow?

Answer by  jkareckygmailcom (85)

When coolant overflows it indicates that the engine is overheating. There could be a lack of coolant,poor quality coolant or a lack of circulation. Check for leaks and make sure the radiators electric cooling fan is operational. Determine if the thermostat is operating properly. Be careful not to burn yourself if the system is hot.

Answer by  florin1666 (42)

It could be a small leak somewhere that prevents the coolant from being sucked back in as the car cools. It could be a hose or a seal on the radiator itself.

Answer by  Amber40 (24961)

When the correct amount of fluid is added to the system it should never overflow out of the reservoir tank. Otherwise you may have air escaping or an internal problem.

Answer by  springc (51)

Most cars have a Thermostat installed in the cooling system. This thermostat is controlled by the temprature of the water and is set to stay open until the water heats. If the Thermostat malfunctions the water and coolant get to hot, causing it to boil and overflow.