overheating

2006 HYUNDAI SONATA
210,000 MILES • 3.3L • 6 CYL • FWD • AUTOMATIC
Avatar
MITZI GIBBS-HARTMAN
  • MEMBER
  • 36 POSTS
after driving the car for a while the temperature gauge needle starts climbing all the way up to high. if I am going down the freeway it cools it back down but when I start going very slow in the neighborhood it is back up.
a compression check was done and the pressure is fine. Does not always heat up though, sometimes I can go all night long without it heating up at all. we are changing out the thermostat now to see if that happens to be the problem.
May 10, 2017 at 6:16 PM
Advertisement
Avatar
CARADIODOC
  • ✓ASE Certified Mechanic
  • 34,321 POSTS
  • ASE Certified Mechanic
You are overlooking the most important clue. Vehicle speed is a factor, and that rules out the thermostat. The most likely suspect is a bad radiator fan motor. That is not needed at highway speed when natural air flow is sufficient. The fan is only needed at low speeds, so if it is not working, that is when the overheating will occur.
May 10, 2017 at 10:15 PM
Avatar
STEVE W.
  • ✓ASE Certified Mechanic
  • 15,200 POSTS
  • ASE Certified Mechanic
Think Doc has it pegged. A bad fan or fan controller will give the exact issue you have.
May 11, 2017 at 6:09 AM
Avatar
MITZI GIBBS-HARTMAN
  • MEMBER
  • 36 POSTS
Except that the fan was checked and it works like it's suppose to. Couldn't the thermostat stick at times?
May 12, 2017 at 9:29 AM
Avatar
STEVE W.
  • ✓ASE Certified Mechanic
  • 15,200 POSTS
  • ASE Certified Mechanic
Not normally. They either work or the fail, no real middle ground where they stick. Could be a bad water pump with a slipping impeller or you have a failing hose or radiator.
May 12, 2017 at 7:07 PM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.