I have a 2003 Pontiac Grandam, last week all of a sudden it started overheating. Temperature gauge maxed out within a 5 minute drive.
I let it cool down ran it a couple of miles at night with no problems. Tried it again the following morning still no problems. At noon it started overheating again. These time even when car is cold and I add coolant it disappears.
No apparent leaks
I fill it up to max capacity and within seconds it's gone.