What is the boiling point of water in a car's cooling system?

Water normally boils at around 212 Degrees Fahrenheit at 1 atmosphere of pressure. Raise the pressure under which the water is stored and the boiling point goes up. The addition of a chemical such as Ethylene Glycol also elevates the boiling point. So the answer depends on how much pressure the system is under and if it has a 50/50 mix of Anti-Freeze and distilled water. Assuming it has a 50/50 mix in the system the boiling point will be around 223 F. Add a typical 14-15 lb/in pressure cap on the system and the boiling point goes to around 268 F. So when your radiator boils over it is HOT!

Water normally boils at around 212 Degrees Fahrenheit at 1 atmosphere of pressure. Raise the pressure under which the water is stored and the boiling point goes up. The addition of a chemical such as Ethylene Glycol also elevates the boiling point. So the answer depends on how much pressure the system is under and if it has a 50/50 mix of Anti-Freeze and distilled water. Assuming it has a 50/50 mix in the system the boiling point will be around 223 F. Add a typical 14-15 lb/in pressure cap on the system and the boiling point goes to around 268 F. So when your radiator boils over it is HOT!