I recently has a similiar thing happen to me. I was on the way to work driving my 92 Cavalier and was more than halfway there when I smelled antifreeze. I thought that it was coming from some cars in front of me so I didn't think much about it. About five miles further I glance down and see my temp gauge climbing so I pull over, pop the hood, and look at whats going on. I can see coolant dripping near the firewall but that is about it.

A friend from work stops when he sees me there and we drive up the road to get some water. I pour water into the radiator and it comes out as fast as it goes in. I had the car towed home and long story short, I blew one of the plastic lines attached to the heater core. I had to install a new heater core which was a fun job.

Wayne