[postlink]https://automotivideo.blogspot.com/2012/10/the-radiator-cap-work.html[/postlink]http://www.youtube.com/watch?v=0JdDWWoX-70endofvid
[starttext]The radiator cap is a product of brilliant engineering. Its basic design is of two coaxial, spring-loaded, one-way gates, that open in opposite directions. This design allows for self regulation and safe engine cooling in an elegant, simple design. The lowly radiator cap is the hidden genius behind an engine's cooling system.
Because filling from the reservoir relies on a natural siphon effect, it is critical that an air tight seal be maintained at the radiator cap and adjacent structures.[endtext]