In a message dated 96-11-09 10:40:47 EST, hiker1@fuse.net (Richard Fischer)
writes:

<< 
 That's the background. Now occasionally after this, I'd check the overflow
 tank and it would be empty. So I fill 'er up with 50:50 coolant. All would
 seem fine. Then later she's be empty again. So I'd do the same. Next time
 I'd check when the engine is hot, the overflow tank would be to the top!
 Then the next time back to near normal.
 
 On a trip last weekend, we had driven about 80 miles and the Oxygen sensor
 and alternator lights lit up but very dimly (it was dark), about 15 seconds
 later, they pulsated and became dimmer, then went out! I pulled over and
 found a mist of coolant on the rear bumper, and when I opened the inspection
 door behind the license plate, again, the coolant was full to the top and
 apparently had blown excess out the top which the engine had apparently
 blown onto some of the sensor wires causing the temporary lights.
 
 I drove another 50 miles, the temperature gauge stayed normal, and the upper
 and lower front vents air temperature felt the same with the heater lever
 full open, but when partially closed, the top felt luke-warm, and the bottom
 warm. 
 
 The next moring, when I opened her up to check things (cold, about 28 deg)
 the coolant was near the normal mark, maybe slightly high. Then after
 driving 150 miles home later that day, and checking often, the coolant level
 stayed "normal" the entire time???
 
 I cannot make any sense of this. Can anyone else?
  >>

You either have a abd pressure cap or your heads are leaking combustion
gasses into the cooling system

Dennis