Recall on Coolant caps

[Jaxonalden]

Joji,

Quote;
Q-"Far as I know coolant can't boil." A-Yes it can, adding anti-freeze raises the boil point of water (212 degrees). The radiator cap is set at a certain pressure (8-15 psi) this pressurization of the coolant system also raises the boiling point.
Q-"Is it the water mixture boiling? do you think it is boiling at all." A- Not possible, the water and anti-freeze is a mixture. If it was the engine would be so hot that you would be getting an idiot light and the temp gauge would be well above 230 degrees.
Q-"Also if it is wouldn't the coolant tank melt since it is plastic." A-The melting point of the tank is well above the boiling point of the coolant. If the tank ever melted, you would have bigger problems on your hands than the tank.