Radiator cap - should it be pressurized?

believe me, you can fell pressure in a hose. I just had a "moment" with beater 2.0 (82 Maz B-2000 P/U) Im cruising up the 210 on my way to pick up some $20 leaf springs and the temperature gauge is never more than 1/2 between hot and cold, more like a tick above low range so Im good to go..la de da..oops, gotta pull over as my pedal linkage has slipped out of the carb (stupid design)..WTF is that steam coming from my hood? I get out and pop the hood and my DIY gatorade puke tank is full and the hose is flipping around like a fire hose shooting green radiator scum everywhere. DAng, I thought I was running fine? I limp it to a gas station and douse a beach towel with cold water and use it folded over about 5 times to uncap the radiator cap to its safety position, well it blows now big time but Im fine as I took precautions and it all just jets down onto the pavement. This thing was freaking HOT! Hmm, I start the motor (starts right up and idles fine) and start adding water slowly. It doesnt back up on my, just fills to the brim and I put the cap back on. Oh, and that upper hose was hot and rock hard BTW. So i drive another 4 miles to my buds house and check cap again, no leaks, no puke, seems ok. WE check the cap, clean both rubber gaskets with gojo and top off radiator, and he hooks me up with a real bottom feeder puke tank I strap to the side f the battery. I am looking at my sender and I notice the brass tit is wiggly, so much so that I pull it right out ! Looks like it broke or came unsoldered to the sender, thats why my gauge was only reading 1/2 as there was little or no continuity in the sender. Well, I drive 50 miles home in LA freeway traffic in 85 degree heat and it never even flinched. I think the cap was not on properly in the first place and the "no pressure" radiator promptly boiled over, loosing coolant and causing a chain reaction that left me high, hot and dry! Get a pressure rated cap, if your radiator starts springing leaks at 7-16 lbs, it was already shot and was about to go on you anyway. Boil over with a 16 lb cap and straight water is 244. boil over with 50/50 can be as high as 275!