John, I wish I had been under the hood (like that BBQ cam the BBQ king uses, on public television) when my brother-in-law's 1987 745 overheated last fall: badly warped head, hole in #4 piston...

I later saw that his car's radiator was badly clogged with fuzz -- never cleaned.

And no loss-of-coolant warning system. (Here's the obligatory "See 700/900 FAQs.")

Receipts showed that his mechanic changed the timing belt at 140,000 miles or so, but did NOT change the original coolant pump. (Having spent $4,000 over 3 years with the guy.)

When I cleaned out the car's filthy engine bay I started finding (here's the point!) little steel balls stuck in the goo on the splash pan... Hmmmm. The pump had spilled its guts. Fairly quickly? Dunno. I bet the driver had the radio turned up kinda loud, and he's not particularly mechanically-inclined anyway.

Moral?
When you see the balls it's too late. ;-)
Clean the radiator, once a decade anyway?
Replace the (low-cost) coolant pump when the whole area is bare-naked anyway for timing belt change.
Install a loss-of-coolant warning?
Don't play the radio too loudly? :-)