You're welcome.
For an additional tidbit... besides functioning as a two-way check valve in the closed cooling system, the radiator pressure cap raises the boiling point of water about 3° F for each pound per square inch of pressure increase above the ambient pressure. So, a 16 PSI pressure cap will raise the boiling point of water roughly 3°/PSI x 16PSI = 48° F. At sea level that amounts to 212° + 48° = 260° F for pure water.
But, a 50/50 mix of glycol antifreeze and water boils at about 8° F higher temperature than pure water. So, at sea level, a 16 PSI pressure cap on the typical automotive wet cooling system that contains a 50/50 mix of antifreeze and water will boil at about 268° F. That's pretty hot!
In summary, a weak radiator pressure cap won't cause coolant temperature to increase, but it will allow the liquid coolant to boil at a lower temperature than intended, which could expel coolant from the system. The resulting loss of coolant, if sufficient, will cause overheating.
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