I recently had the head gasket replaced on my 2001 Elantra but now I have some of the same problems as before. Immediately when the 01 Elantra is started, air bubbles percolate up thru the rad. If I place my hand over the rad opening, it quickly becomes pressurized. Eventually I lose significant amounts of antifreeze and the engine overheats. I think the head gasket is bad (again) or there is a crack in the head somewhere. My father said it could be a blown intake manifold gasket. At present I am adding antifreeze each day and the car will run great. Could the dealer determine the problem with a code reader? Desperate in PA!