It's been a couple of days and the problem still persists; the coolant is not returning to the radiator. I did notice something and it finally dawned on me. Everytime I remove the radiator cap to fill it, pressure is being released. It's like opening a soda can. Even when the engine is cold! I believe since there is never negative pressure in the radiator, the coolant from the overflow reservoir will never get sucked back in.

So now I am wondering if there is a problem with the head gasket allowing pressurized gas to get into the radiator. Like I said in my previous post, there are no obvious problems with the car. There is no oil in the radiator, no coolant in the oil, no steam coming out of the tailpipe, no loss in power or gas mileage. One thing I do notice is, the engine seems to misfire when starting up cold. I rap the throttle a couple of times and that clears it.

Should I open another thread on this topic to get responses from others? Thanks!