hey, i have an 88 iroc-z and i just changed the thermostat because the upper radiator hose was swelling, it seemed like it wasent opening, but when i out the new one in it dident change anything, i drained the antifreeze and when i tryed to get the air out of the system, all it did was bubble or foam out of the top of the radiator. and the antifreeze level never droped, like the thermostat never opened. any opinions of where i could go next? i read on here that these symptoms maybe a blown head gasket. i hope not

 

Is your radiator fan going on? If no, then the engine will overheat.

 

Drain the entire system. Radiator AND block. (Find your block drain plug -on the bottom of the engine, one on either side) Take off your thermostat housing and fill the block. Replace t-stat and housing, now fill radiator. At this point your cooling system should be about 90% full. Start the engine with the radiator cap off. Add coolant as needed. Once you see the coolant in the radiator flowing and all you are all topped off, cap the radiator.

Head gasket? Dont get worried yet. Check your oil for any milky white or brown contamination. Thats usually the sign of a internally blown head gasket.