Now here's a mystery for the 240 experts that has me stumped...

A month or so ago I was driving through the mountains of Colorado. It was a dark and windy night, 10 p.m. and 7 degrees above zero. I started hearing a squealing (bearings?) sound from the engine of my 1984 245. I stopped to look, but with the dark and wind, I couldn't tell if the sound was coming from the power steering pump, the A/C compressor, the alternator, or ?. It was really loud by this point. I did notice that the power steering fluid was low, so bought some and topped it off, hoping for the best.

Being 50 miles from home, I decided to chance it the rest of the way.
The squealing continued, but didn't get any worse.

The next morning, I started it up to pull in the garage to have a look. It ran fine! Quiet as a mouse. I cautiously drove it to work, and amazingly (to me at least) it continued to run fine for another month.

Then.... last night (again cold and windy) I heard a pulsing sound from the engine, felt an odd vibration in the stick shift, and then suddenly something screamed (under the hood) and the engine locked up. I yanked the car off the side of the road, shut it off, and opened the hood. It was dark, but by the light of the silvery cell phone I could see that the belts were fine. I restarted the engine to see what was sticking...lo and behold, there was no unusual sounds....for about 5 seconds, then it started screaming and it was obvious that something had seized between the crankshaft, A/C compressor, and power steering pump. It was too dark to see exactly what. Given the darkness, temperature, and my mood at the time, I locked up the car and had a pleasent walk home.

This morning, I went back and, without starting it, loosened the power steering pump and took off the belt. I cut off the belt between the A/C compressor and the crankshaft since it's no small job getting those 6 (?) bolts off the front of the water pump. (Note, it's light now, but about 23 F).

Here's the mystery. Both the power steering pump and compressor spun freely. I didn't even notice any binding or bearing grinding. I'm stumped. Any thoughts would be much appreciated.

Thanks!
Mike in Colorado