Hyundai Repair: Hyundai 2002 2.0 overheating, coolant level, coolant temperature

Question
my Hyundai is overheating with the coolant in the reservoir tank boiling over and coming out the relief hose. were is the thermostat located? we went to replace the thermostat and got confused about where exactly it is supposed to be.  we found what looked like part of a thermostat in a part that a diagram for the 2002 model stated it should be at, but when we placed it in there we still had trouble with overheating.  do you have any diagrams for the 2000 model and any advise as to what i should be doing here?

Answer
The thermostat is located in a housing in the tranmission end of the engine.  There are two 12mm bolts holding the housing in place.

If, when you installed the thermostat, there was one already there in place, you've found the right place.

Anytime you have an overheating problem, you should do a thorough check of the cooling system.  

First, after the vehicle has cooled, remove the radiator cap and check the coolant level.  If it's low, check for leaks and repair any found.  (Since you're boiling coolant out of the reservoir, I doubt this is your issue, but this is the simplest of the steps and shouldn't be overlooked).

Once you have ensured the coolant is at the proper level, leave the cap off and start the car.  Once the car reaches operating temperature, the coolant should begin to flow.  If you have trouble detecting this due to the shape of your filler neck, you can monitor the radiator hoses.  The upper hose will get hot first.  Once the coolant begins to flow, the lower radiator hose will get hot as well.  If the coolant begins to boil prior to the start of flow, you'll need to check the cooling system for blocakages.  Presuming the new thermostat is installed properly and operating normally, you should primarily be checking for a clogged radiator if the coolant won't flow.

If the coolant begins to flow normally, the cooling fans should eventually cycle on and off to manage coolant temperature.  If the coolant flows but begins to boil prior to the fans cycling, then you'll need to diagnose why your fan isn't turning on.

You can find the service manual for your car at www.hmaservice.com.  You'll need to register for a free account, and the site requires Internet Explorer.