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Overheating in stop and go traffic and during idling

Tiny
VISH4369
  • MEMBER
  • 2004 HYUNDAI SONATA
  • 2.4L
  • 4 CYL
  • 2WD
  • MANUAL
  • 90,000 MILES
I recently bought this car a week after I noticed that the car is overheating in traffic and while idling.
Things I observed:

I checked for bubbles to see if itis a head gasket no bubbles found.

No leaks and I am not losing coolant.

Heat and AC both working fine.

The gauge is creeping hot if the blower is on with heat and AC and drops down if I turn it off.

Lower has thermostat housing in this car. Lower hose stays cold most of the time and gets hot sometime either way car overheats.

Coolant temperature sensor has 3 pins I understand there are for volt, ground and gauge do not know which one is which. I probe with multi-meter for volt 1 read 0, 2 reads 10.5 and 3 reads 5.6

raditor fans not kicking on, it works if I unplug sensor.

Please help me out.
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Saturday, December 16th, 2017 AT 12:16 AM

14 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Good work testing the temperature sensor. I would go ahead and change that sensor and the thermostat as well. That should definitely solve your problem.
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Saturday, December 16th, 2017 AT 2:49 AM
Tiny
VISH4369
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  • 32 POSTS
Okay, I will do that and share the update. Thank you.
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Saturday, December 16th, 2017 AT 10:48 AM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
I changed the sensor today. Then I top off the coolant and was making sure by checking for the bubbles. I kinda see bubbles like 3 or 4 at a times and don't see them for a while and see them again( it was raining slightly assuming it's rain causing it bubble - correct me if I am wrong and educate me if it's head gasket related issue ) after I changed the sensor and ran car in the first engine was creeping hot my fans kick on for a while still engines over heating so I shut it off I ran the car again then it creeped little over operating temps and come down again then it never creeped up again til now. Need explaination why it creeped hot in the case if you can please. Other than that everything seems fine now but I will be checking it for a week before I igonre it. Thanks for your help
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Monday, December 18th, 2017 AT 1:45 PM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
It didn't work after running it for an it's over heating again
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Monday, December 18th, 2017 AT 2:51 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
I think it's time to check for a blown head gasket. Here's a guide on how to check it: https://www.2carpros.com/articles/head-gasket-blown-test

In particular, the check for exhaust gases is (in my opinion) the most important test. Do that and get back to us.
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Tuesday, December 19th, 2017 AT 3:54 AM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
I replaced thermostat even the old one still looks good. Flushed the coolant. Yesterday it seemed fine that fan were turning on automatically and shutting off. But this morning its was foggy snowing and while I was car indicator creeping up since I have an obd scanner I checked the coolant temp it was about 195 F I pulled over checked for fans. There were dead and not coming on. Indicator reached all the up obd sensor reading 195 F. Is 195 F is the ultimate temp or my sensor bad again because its a new one
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Wednesday, January 3rd, 2018 AT 9:48 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,313 POSTS
Hello,

It sounds to me like you have an intermittent fan issue which can be caused by the radiator fan motor or relay. Here is a guide that that will help us do some testing.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

https://www.2carpros.com/articles/replace-electric-fan-motor

Here are the diagrams for your car (below)

This guide can help as well.

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Check out the diagrams (Below)

Please let us know what happens.

Cheers, Ken
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Saturday, January 6th, 2018 AT 12:52 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
195 is about what your car should be running at. The fans will come on and go off as needed to keep it in that area. To test, I'd turn the A/C on full blast and watch under the hood while it idles. You should see the fans come and go. Unless I'm missing something.
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Saturday, January 6th, 2018 AT 7:08 PM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
My fans for coming on at 207 -209 range and not before that. And at 207 temp guage creeping high or very close to red but not on red.
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Monday, January 8th, 2018 AT 1:10 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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It sure sounds like a blown head gasket did you do the test Heyman suggested?
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Tuesday, January 9th, 2018 AT 10:50 AM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Your car has three different fan speeds possible. There is a separate relay for each one. The PCM activates each speed at different coolant temperatures. They're all in the underhood power center/fuse box. You can swap them out and see if the behavior changes. If it does then just replace them. They appear to be pretty standard relays that should be available at AutoZone for a decent price.

Sorry it took me so long to get back to you. I thought I had said this yesterday. I must not have clicked "Reply."
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Tuesday, January 9th, 2018 AT 1:17 PM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
No I didnot do block test for observed for bubbles in the radiator, checked for oil in the coolant and checked engine oil for any sweet smell and for thickness or white substance
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Tuesday, January 9th, 2018 AT 1:59 PM
Tiny
VISH4369
  • MEMBER
  • 32 POSTS
I am assuming 207 is not ultimate temp for guage and this wont happen all the time. For example if I drive for an hour and stop and idle with blower on high the guage creeps up high but obd scanner stay ay 207 or 205 and it comes down slowly when I trun off the blower
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Tuesday, January 9th, 2018 AT 2:05 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Again I say, check the relays. The low speed one should be kicking on well before 207.
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Tuesday, January 9th, 2018 AT 7:15 PM

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