When your GMC radiator gives you clues that it is starting to overheat, pay attention! Your radiator is telling you that it might boil over...and at that point, your entire engine system is in serious danger. When an engine faces extreme heat stress, the head gaskets will blow and the heads might crack, which will lead to complete engine collapse. At that point, you might be faced with scrapping your GMC vehicle entirely, or paying major repair bills. The gauge on your dashboard might hover a little longer on the 'H' range, and you might see a little steam or haze emitting from the hood. You'll smell a 'hot,' acrid odor, which is the coolant and water evaporating. The air conditioning might be on the fritz, and you will hear a hissing sound. Sometimes, these symptoms will only appear when the car is idling. These symptoms could stem from multiple issues in the cooling system, so take the time to make sure your GMC radiator is failing. Other causes could be a stalled thermostat, a cracked or crimped hose or a failing cooling fan. You can diagnose a failing radiator with a coolant pressure system gauge. If you determine that your GMC radiator must be replaced, purchase a new, reliable part from our site.