heater blows cold

I am new to this, so bear with me. I have a 2000 Chevy Cavalier with approx. 114,000 miles. While driving, the heat suddenly stopped working, and it kinda made some gurgling sounds. I pull over and popped the hood. The engine was smoking/steaming. It looked as though some coolant was leaking out of the resevoir overflow. But because of the heater suddenly blowing cold air, I am guessing this would be a blown head gasket ?? Can anyone confirm this and/or think of any other potential causes. Is there anything else I can look at to determine the problem. I have been reading through these forums and some are talking about replacing the water pump or thermostat, could these be the problem? Any guidance would be helpful. Thanks :sly:

it could be any of those things.. or a cracked block cracked head.. was there any sound coming from the waterpump area before it broke down? this could be a good indication if its good or not.. you can take your thermostat out and put it in a pot and boil it to see if it opens. check your oil if its milky then you for sure have a blown head gasket

I'm sorry but this has been addressed way to much lately.... here's a link to serverl posts regarding heater problems...

http://www.automotiveforums.com/vbulletin/search.php?searchid=748429

more than likely your thermostat stuck CLOSED. This does not allow the hot water from the engine to circulate through the heater core, causing the heater to blow cold, and it also prevents the water from going to the radiator to cool off, thus causing your engine to overheat. Word to the wise, if you replace the t-stat, you will create an 'air-lock' in your engine, (pocket of air at the water pump that will not allow the pump to move the coolant). My girlfriend has a 2002 Cavalier that this happened to about 2 months ago. You have to bleed the air out of the line, or else it will seem as if you have the same problem. Not sure how it is on the '00's, but on the '02, the bleeder valve is all the way on the opposite side of the engine. Follow the silver line that comes off of the t-stat housing up and around the driver's side of the engine. There should be a little bleeder up there somewhere that has a 7mm or so nut on the top. after replacing the stat, let the engine warm up to until your cooling fan turns on and then turn that bleeder valve to let the air out......stop when the antifreeze starts coming out. I found it best to do this a couple of times....shut it off and let it cool and do it again. You can stop when you are comfortable enough that there is no air left in there.
If you shut the car off immediately when it overheated, I don't think you would have a cracked head gasket.....but definitely, if you do notice a milky white substance like Mangoamerican mentioned, on the underside of your oil-fill cap in the near future, i would get the head gasket checked out.....Hope this helps! :)

Well I checked the Thermostat by boiling it...It works fine. There does seem to be some rust colored milky residue on the underside of the dip stick CAP, but the oil on the dip stick seems fine.. 1.)Would there also be a milky residue mixed in the oil if the head gasket was blown ?

My girlfriend mentioned that the couple of days before, the engine started to sound as though it was idle-ing strange. It made a high pitch reving for a while then it would go back to normal. 2.)Could this have been the water pump crying out?

I guess my next task is to check the water pump. Since the 2000 Cavalier does not have a radiator cap, (only a resevoir cap) I was unable to check to see if the water level started churning when the pump went on. 3.)I have already drained the coolant so If I take the water pump out, is there any way to test it? :uhoh: