Hyundai Repair: 2002 Elantra Gls Radiator, radiator tank, coolant level

Question
my 02' elantra has been working fine for the past week, no problems( i just bought it). two days ago the top of my radiator started steaming, and then my engine temp shot up! i put this B&G welding stuff to cover the hole(i've done this to previous cars before) and it worked fine for about 20 min. then it blew again! i figured i missed a spot so i piled on the welding stuff, but then this morning to start my car, i noticed my idle temp was just a little over the normal so i stopped my car check it out, drop it back home and then it blew again! i had my heater at half blast and no heat, and my Elan is heating up, and that stupid hole! how can i fix it? please help.is it just the whole or are there other problems?

-2002 Elan

Answer
You're at least going to need a new radiator.  It's also obvious that there's an issue with the coolant level (no heat).  Probably, either your coolant is leaking out (unlikely-- you're building up enough pressure to pop the radiator) or you have a faulty thermostat.  At this point, you should also look in the radiator opening.  If you see goopy grey stuff, your radiator tank has melted and clogged your radiator.