About 4 months ago I had to flush out the heater core of this blazer. Worked fine. The other day temp rises just going down the street and radiator steam comes pouring out. Dry. I fill up the radiator and overflow with coolant after having to literally break off the radiator cap because some demon won't let go of it.
Runs fine for one day.
Next day I smell what smells like burning coolant. I drive down about 5 miles and again with the smoke from the radiator. I try to check the coolant level in the radiator and guess what? New cap, will NOT come off. The overflow is totally empty. There is no sign of leaking anywhere,I have no idea where this is going. The temp runs very high and I am not running air or heat. I want to assume its the thermostat, but am thinking it could be the heater core again?
Any suggestions? Please?

 

could it be a bad radiator hose? could be your water pump.... your radiator might have a crack in it.... theres a few things here. is there any leaking into the car from the heater core? not sure why the cap keeps getting stuck!

 

If you don't have coolant in the oil, then there is a leak somewhere. And if you overheat it, bad things will happen. If there is any air in the system, bad things will happen. You have to get any boiled coolant out via a good flush and make sure to remove ALL of the air from the system before doing any real driving.