I'm of no help, as usual, but I want to share a story about back in the day before I became a car guy....
I had an 86 Pontiac that I bought used. I was going to a golf outing to meet up with some guys from work. It's REALLY hot that afternoon, and I'm stuck in traffic. So I notice the temp. gauge going to where it has never gone before. So I turn off the AC, and wind down the windows. That didn't help me or the engine get cooler.
So I'm a couple of miles from the golf course, and the needle is pegged at 260* on my dash. I pull over and open the hood, and see my overflow bottle is boiling. I give it 10 minutes, it's still boiling. Well, I'm now going to be late if I don't start this piece of hot lava of an engine up soon. So, do I care about the engine? No. I start it up, and every time I give it gas, it pings it's arse off. I get to the golf course and figured it had a few hours to cool off. Luckily, I had a couple of gallons of water in my trunk, so I refilled the radiator and made the 30 mile drive home just fine. It turns out, my radiator had hardening of the arteries because coolant flow was greatly restricted by corrosion. I sold the car years later with 147,000 miles on it, and the engine still ran like a champ, despite my stress test.
