How to change the thermostat on a 2000 Hyundai Elantra. A step by step guide.
Use eye protection and gloves. Hyundai recommends disconnecting the battery (but I did not and everything was fine). Get the new thermostat. I went to Advance Auto and got a new one for about $12. Get a new thermostat gasket for $2, get PermaSeal gasket sealant for$3. Test the new thermostat and make sure it works well. Get a large pan and start boiling water. Using nose-head pliers, dunk the new thermostat fully in the boiling water. In a minute or so, the thermostat should start to open. If it does not fully open after a few minutes, then it is defective. Let the engine cool down. Put stoppers behind around wheels for extra safety. Open the radiator cap. Drain the radiator antifreeze coolant. Do not throw away the coolant. You can re-use it. Many coolant manufacturers give 100k miles warranty. Use a large pan to catch the coolant. I used a clean aluminum foil pan that came with the 50 piece chickens I bought for a party. Some people also filter the used coolant using layers of old towels.The petcock or the drain plug is on the passenger side towards the very bottom of the radiator. You can twist it off using nothing but your fingers. You may need to lie down on the floor and reach from the bottom of the car. The Upper radiator hose, the bypass elbow hose and the lower radiator hose, all 3 of them attach to a common place on the top of the motor. The radiator is located at that junction. Seethe photo to locate it. The thermostat housing is held together with2 bolts. See photo. Put a towel underneath the thermostat housing to catch the coolant. Remove the bolts using a 12mm combination wrench. Notice how the old thermostat is sitting. There is a notch on the top of the thermostat housing. It is also called a bleed hole. That is always on the top.The spring side of the thermostat goes inside the motor. The pointy-hat side faces the hose. Take digital photos if you have to.Remove the old thermostat and gasket. If the gasket does not peel off easily, get a gasket remover knife or a thin razor blade and carefully peel off the old gasket for both mating surfaces. If there is corrosion or other debris on any of the 2 mating surfaces you can also use a ultra fine sand paper and rub it off. People told me that they also had success using nail polish
remover, rubber/paint thinner etc.If you use any chemical, make sure it does not drip on the hoses.Make sure both metal mating surfaces are shiny and smooth when you are done. Wipe clean the whole area with a slightly wet towel.Take the sealant and put a very thin coat on both sides of the new thermostat gasket. The sealant is very thick and sticky. Clean one hand. First, place the new thermostat inside the housing with the clean hand and hold it there. Then, use the dirty hand to place the new sealant coated gasket on top of the thermostat. The gasket will stick to the housing and hold itself along with the new thermostat and then you can remove your hands. Make sure the new thermostat's orientation is exactly how it was before. See the digital photo if you need to. Place the other mating surface on top of the gasket.Put a little bit of sealant on the threads of both bolts. Quickly slide in one of the bolts and hand tighten it. For the second bolt,you may need to jiggle the mating surfaces a bit to align the holes.Hand tighten the second bolt. Carefully inspect everything before using the combination wrench to properly tighten the bolts. You will see the sealant paste squeezing out of the side edge when tightening the bolts. Let it dry for a few hours before refilling the radiator.