Mine did this too just the other week. I bled the system and everything is fine now. Where the thermostat goes, theres 3 bolts i think that the radiator hose plugs onto. The offset bolt is the one you want to remove, poor coolant ect (i used distilled water) into the radiator until it starts to bleed from that hole. Put the bolt back and give it a try. Do this while the car is cool. Goodluck hope it helps