2004 H2 overheats.

[IRA51]

Is it useing coolant ? if it is you need to find the leak . if not it may be a cloged radiator and you may need to have it rodded out or replaced . as said B4 if you mix Dexcool with the green antifreez it will clog the system. if it's a bad head gasket it wiil show up at the tail pipe as a mist or worse. you can also pull the spark plugs and see if they look right ,if one is a differant color you can bet that you have a leak in that chamber and it is ether a cracked head or bad head gasket . head gaskets go bad on these engins because people never change the coolant and beleive GM that Dexcool is good for 100000 miles ,in fact you need to flush and change it with a thermostat every 50000 miles or 3 years which ever comes first .