Scalding coolant erupts after man removes radiator cap - GIF

[Frank S]

The engine is toast, and he is boiled. here is my explanation why what he did was a bad idea.
first and foremost it is not a risk of personal body injury it is a guarantee it is going to happen.
secondly if there was any coolant still in the system it is better to leave the system pressurized to cool down a proper mix of antifreeze and water will not boil under pressure until over 260°f but if there is steam already escaping from the cap it means it is well above that threshold of becoming superheated steam.
Once the pressure is released any cooling ability from what little coolant still in the engine is lost, and any possibility of salvaging the engine without further damage is greatly reduced.
Leave the cap in place slowly and carefully dribble water over the outside of the radiator a little at a time or simply waiting until it has cooled down naturally is the only chance of possibly salvaging the engine and even that chance is slim with the newer smaller aluminum engines