I started having a problem a couple of months ago. My air conditioner worked fine but at redlights or upon slowing down, the temp gauge would start to go up and the air would stop working. I had a friend look at it. He said both fans were working and it seemed like something (i cannot remember what) was not engaging at lower RPMs. He said I may just need some oil (installed like refrigerant). He told me to put car in Neutral at redlights and rev the engine to keep it from overheating. I did this successfully. Each time I would stop, I did this and it worked like a charm. Well, the last couple of days, the temp gauge has been redlining. I put coolant in the radiator but it hasn't help. I know very little about cars and don't know anyone else that does either but I am hoping someone here can help me diagnose. I popped the hood last night as soon as I stopped and the coolant was boiling. The upper radiator hose was really hot. I looked up under the space where the radiator hose connects to the engine and saw lots of hard, crusty whitish rock like stuff around the hose connection to the engine. I could chip this off relatively easily. I am not sure what this is. The hose looked like it had a good connection. I know I need to take it in to be serviced but to be honest, I am single with a kid in college and I just can't afford to be taken advantage of...I am scared this is what will happen. If I had some idea of what it could be, I would feel better about dealing with a service department. I bought a new Thermostat (after hearing how easy these were to change out) but I looked and could not find where this would go. If it could be the Thermostat, can someone tell me where this is located? I appreciate any and all advice. Thanks, Sheila

I seriously think you should seek help on a Elantra oriented forum :

elantraxd.com

if you search the forum you'll find LOTS of answers about thermostat;

http://www.elantraxd.com/forums/showthread.php?t=24995
http://www.elantraxd.com/forums/showthread.php?t=18400
http://www.elantraxd.com/forums/showthread.php?t=15880


and here is a DIY thermostat change, not for the Elantra but the thermostat location is nearly the same (it's in the same area);
http://jalopnik.com/cars/car-care/and-you-will-know-us-by-the-trail-of-parts-replace-a-thermostat-240953.php

This forum is not extremelly crowded with Hyundai enthousiasts as we get laugh at a lot.

You rock, J!

I didn't realize I would be the subject of other's ridicule for having an Elantra :( I mean, I know it's not the coolest car in the world but it has been a great car up until now.

Well Hyundai in general have a bad rep. but I never had bigger problems than with any other car I had, either domestic or imported, Hyundai's car are really the best bang for the buck you can find out there and they are fun to drive! :)

Good luck with your overheating problem! :)

I started having a problem a couple of months ago. My air conditioner worked fine but at redlights or upon slowing down, the temp gauge would start to go up and the air would stop working. I had a friend look at it. He said both fans were working and it seemed like something (i cannot remember what) was not engaging at lower RPMs. He said I may just need some oil (installed like refrigerant). He told me to put car in Neutral at redlights and rev the engine to keep it from overheating. I did this successfully. Each time I would stop, I did this and it worked like a charm. Well, the last couple of days, the temp gauge has been redlining. I put coolant in the radiator but it hasn't help. I know very little about cars and don't know anyone else that does either but I am hoping someone here can help me diagnose. I popped the hood last night as soon as I stopped and the coolant was boiling. The upper radiator hose was really hot. I looked up under the space where the radiator hose connects to the engine and saw lots of hard, crusty whitish rock like stuff around the hose connection to the engine. I could chip this off relatively easily. I am not sure what this is. The hose looked like it had a good connection. I know I need to take it in to be serviced but to be honest, I am single with a kid in college and I just can't afford to be taken advantage of...I am scared this is what will happen. If I had some idea of what it could be, I would feel better about dealing with a service department. I bought a new Thermostat (after hearing how easy these were to change out) but I looked and could not find where this would go. If it could be the Thermostat, can someone tell me where this is located? I appreciate any and all advice. Thanks, Sheila

Sheila, I am experiencing exactly the same problem in the same manner as you described, did you ever find out what the solution was? Please email me at bodenj@yahoo.com (bodenj@yahoo.com), thanks jim.

Hi, i own a 2005 elantra. I am experiencing exactly the same problem just as you described even the white stuff on the hose connection, have you found a solution, please let me know. Jim at bodenj@yahoo.com

Go to elantraxd.com.....ask for help...they will help you!