>>>When you lose coolent does it pull it from the overflow tank ?

If it is that suggests that your system is pressure tight, otherwise it

would pull air from the leak rather than fluid from the overflow.


I would look for a pinhole in a hose, opens under pressure, but pulls
closed under vacuum.


I would have thought this would show up in a pressure test though.
>>>

It pulls the coolant in from the overflow tank. Thanks for the ideas.
I'm going to drive it up on ramps, and get under it with a flashlight
and look for leaks / residue of leaks.

I'm also going to take off the air intake tube tomorrow if I get a
chance, and look inside there again, and look for any signs of leakage
into the throttle body or intake manifold. I remember seeing some
discoloration on the lower part of everything in there, but it was a
brownish color, not a green antifreeze color.