Where is the thermostat and do you have to replace it or can it be repaired you just had your coolant replaced and now your car heats up to above 200 in about 5 min?
You really don't want to try to replace the thermostat. It's a bear to get at and it's almost certently not the problem. When you change the coolant, air is left in the cooling system and has a tendency to collect in areas where it is trapped and restricts flow. To correct this there are two small brass bleed screws provided to "burp" the system. One screw is on the thermostat housing which is connected to the upper radiator hose, the other screw is on a black riser near the water pump. To bleed the air (burp) the cooling system warm the engine to pressurize the cooling system. Use a nut driver or socket on a long extension to open the bleed screws a turn or two, use care to stay back from the hot coolant. Again you do not have to remove the screws, they have a small hole which is opened when the screw is loosened a turn or two (similar to brake bleed screws). Wait until you get a steady flow of collent which shows that all of the air has been removed from the cooling system. This should do it, if it needs to be done more than a time or two, you are probably getting air into the system from another source, possibly (as in my case) from a blown head gasket allowing combustion gases into the water jacket. If this is the case repost and we can talk about it. Head gaskets arn't impossible to do for the reasonably hand shade tree mechanic, or just fork over $2000 to the dealer and be done with it. See ya 94