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04 Kia Optima 94 Isuzu Trooper
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Discussion Starter #1
04 optima 4 cylinder automatic.
New Thermostat. New Radiator. New Sending Unit. Will sometimes drift into the red and then back down to normal. I put an analog gauge and saw that the real temp is sometimes rising to 200F. If I turn on the heater it will go back to normal area. Any ideas?
 

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try here
http://www.kia-forums.com/kia-magentis-optima-forum/51528-2001-2-4l-optima-overheating.html
http://www.kia-forums.com/kia-magentis-optima-forum/40242-03-optima-overheating.html
http://www.kia-forums.com/kia-magentis-optima-forum/42325-2002-kia-optima-overheating.html

And now, update your profile, please, and then - if did not find explanation on the forum (try search other cars too - overheating is universal problem) - provide much more details.
Such as when does it happen? A/C is working? Is the system pressurized? and so on...
 

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04 Kia Optima 94 Isuzu Trooper
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Discussion Starter #3
OK profile is updated.

The car (temp gauge) seems to drift high when the AC is on and in idle - but it will also drift high (into and close to the red) going down the road. First we had the sending unit replaced - but it still happened. Then we put in a new thermostat - it still happened. Then we replaced the radiator. It still happened. Today I put in an after market sensor and gauge so that I can see how high it is really getting. It first settled in at 185F when the AC was on and in idle it drifted to 200F. (Is that an okay operational temp?). I turned on the heat and hot air comes out and the temp settled back to 185F. I replaced the original sending unit and now I can't get the problem to reoccur.
 

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have you ever noticed that before?
Well, this temperature (185F is 85C) is normal, low normal operating temperature.
200F (93C) is not too high though. Water boils at 212F (100C), but coolant has higher boiling point (230F, 110C) in pressurized system.
So, it is not overheating yet. If you do not go over 95C, 203F, you should be fine.

You see, the thing is that in the front of coolant radiator is A/C radiator. If A/C radiator is hot then air cooling A/C radiator first will be already hot when reaches coolant radiator. This makes coolant hotter and forces fans to stay on.
Here is the trick. A/C has to be fully charged (not OVERCHARGED nor UNDERCHARGED) so that A/C radiator does not have to cool A/C fluid all the time.
Overheating will take place when A/C is not fully charged. A/C compressor will be constantly on or with very short breaks. A/C radiator will become hot, much hotter than it should be - and rest you know...


Have A/C checked by someone who is able to check BOTH - high and low pressure.
But as of now I would say it works fine.


BTW. My 2007 Rondo gets around 82-85 while driving, idle (on hot) may get to 93. When A/C is on while driving not less than 85, normally around 87, idle up to 95. And it is a new car (well, 1 year old). All temp in C.
 

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04 Kia Optima 94 Isuzu Trooper
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Discussion Starter #5
Thanks!
I never noticed it before, but bought it last Fall and only now using AC
I'll look into the AC charge.
 

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04 Kia Optima 94 Isuzu Trooper
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Discussion Starter #6
Conclusion - It was the connector to the temperature sending unit. Bad connection was causing problems. Now that the connector is in another position no problems. I plan to get a connector from a salvage yard and solder in a new one.
 

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2004 Kia Optima LX 2.4l I4
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need to pick my fellow Optima owner's brains a little more on this issue

:confused:
I need help also...I also have a KIA, 2004 Optima 4 cyl AT (same as the poster of the original question of this thread), and I'm having very similar issues with my car overheating-however what's different with my car (that even after researching on this site I really haven't seen a thread which someone has had or addressed this scenario) is that it will NOT overheat if I turn/keep the AC ON, either while driving or at idle...specifically once the car is warmed up, on warmer days (70+ deg F) the temp gauge will rise from normal operating temps (the same as what's been previously mentioned in this thread) to pegging in the red (at least on the times that I let it or didn't catch it until then on accident), especially under idle...now if I turn on the AC while the car is overheating, the needle eventually stops rising and lowers back down to normal operating temps...car has 45,000 miles on it and is only driven (mostly city) up to 15 miles a day, and what I've tried so far to correct the issue is: radiator coolant flush and fill (and it's full), new coolant temp sensor, new thermostat, and new radiator cap...car has no leaks, hoses are in good shape (and do not collapse when engine is hot and running), and car runs smooth otherwise...also this whole time the CEL has never lit up...I'm not really sure that what was suggested previously above could apply torward my car also...otherwise could it also/either be a bad gauge, bad ground, bad water pump or something else I haven't thought of? Thanks in advance everyone :cool:
 

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Do one test. Warm up the car, or after you drove back home, when car is still hot, turn off the A/C and observe (carefully) both temp gauge and listen to radiator fan.
Another thing you may do. In city driving let it ALMOST overheat and when it gets to this above normal point, drive it on HWY or at least for 3 minutes with speed no less than 40 MPH.
From this what you say I can conclude the radiator fan does not turn on when engine gets hot. BUT it will start working when A/C sends impulse that A/C radiator has to be cooled down.
So, I am not sure but maybe the relay is faulty (does it have separate relays? I doubt...)
I need to check, or you do that on the car, if radiator has a temperature sensor. Some cars (older ones) had sensor in radiator that activates the radiator fan. It could be faulty.

And one more thing. Does it overheat? You see above, the car actually did not overheat, but the gauge was misleading.
 

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2004 Kia Optima LX 2.4l I4
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Wow thank's for the quick response and tips PLP...Yeah I was thinking that it also may be a possibility that it's actually not overheating but only acting like it is...unfortunatley I don't have the tools or knowledge to figure out how to figure out if the car is acutally running hot (without actually relying on the gauge itself)...in the meantime I'll try out your other suggestions and post what I find out...Thanks again
 

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you are very welcome

actually you may. the easiest way to check it is to see if the coolant is boiling. Even more, you do not have to really see it, you will hear it.
 

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I have a very similar but different problem. I have a 2004 Kia Optima which is having issues with the temperature or temperature gauge. I had a problem where the temp gauge would rise, but if you turn off the car and turn it right back on, the gauge reads normally. Then after a little while, it will rise again or sometimes it won't rise for several minutes.

I had the thermostat and temp cooling sensor changed. It worked great for almost 2 weeks. Then it started this pseudo overheating thing again. So, we changed out the temp cooling sensor and thermostat. When we pulled the thermostat this second time, it was stuck open. So, we thought, we had it fixed.

Unfortunately, it has been almost 2 weeks again and the problem has arrived once again.

I think something is either causing the temp sensor or the thermostat to go out. But I have no clue where to go from here.

I have read this and a couple of other threads, and noticed an issue with the AC refrigerant. I will attempt to see if turning on or off the AC causes a difference with the cooling reading.

Has anyone seen a problem where the gauge is reading that it is hot, but if you turn off the car and turn it immediately back on that the temp reads normal for a at least 45 seconds before it starts to move anywhere ( if not longer)? I have actually turned the car off and right back on before and it didn't show the car overheating for at least 20 minutes once.
 

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well, there could be a few things.
coolant circulation and thermostat hesitation - once you turn off engine (engine, that is overheating) hot water/coolant will force opening of thermostat, once you turn it back on - hot coolant will be replaced with warm/cold and it stays like that for longer or not ...??
problems with ground on dash board or the sensor/gauge itself - check all cables
A/C issues - do what you said you would - look for any relation between A/C and engine temp

One more thing you can do - put a separate temperature sensor (go to autozone or something) and see if this independent reading is the same
 

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I have a very similar but different problem. I have a 2004 Kia Optima which is having issues with the temperature or temperature gauge. I had a problem where the temp gauge would rise, but if you turn off the car and turn it right back on, the gauge reads normally. Then after a little while, it will rise again or sometimes it won't rise for several minutes.

I had the thermostat and temp cooling sensor changed. It worked great for almost 2 weeks. Then it started this pseudo overheating thing again. So, we changed out the temp cooling sensor and thermostat. When we pulled the thermostat this second time, it was stuck open. So, we thought, we had it fixed.

Unfortunately, it has been almost 2 weeks again and the problem has arrived once again.

I think something is either causing the temp sensor or the thermostat to go out. But I have no clue where to go from here.

I have read this and a couple of other threads, and noticed an issue with the AC refrigerant. I will attempt to see if turning on or off the AC causes a difference with the cooling reading.

Has anyone seen a problem where the gauge is reading that it is hot, but if you turn off the car and turn it immediately back on that the temp reads normal for a at least 45 seconds before it starts to move anywhere ( if not longer)? I have actually turned the car off and right back on before and it didn't show the car overheating for at least 20 minutes once.
Yes! I have the EXACT same problem. I have been having this problem for too long and usually kill the AC and turn the heater on to make the gauge go normal. If I shut off and turn on, its back to the normal level.
I have flushed the cooling system, replaced the radiator and removed the thermostat with the same exact symptoms. I haven't replaced the sensor yet.
ONe thing I do notice is my gauge can jump into the red and go back down and the Check Engine LIght never comes on. I'm not sure if it would in a true overheating situation or not but its worth noting.
I'm out of ideas as well other than it being some electrical issue.
 

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I have 04 Kia optima my car is of course it reads overheating. changed thermostat once got a flush done dealer says it reads wrong ,but couple things I notice when it reads high it seems like lossing power, A/C seems like not blowing as cold when the gauge reads normal it's like everyone else says yes when I turn A/C off it helps my car overheats on high speed when it starts to move up and down it's like that all day also when the gauge shows its overheating I turn the car off start it right back it goes back to normal do you think it would be water pump it's kind of noisy
thanks
Can
 

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I have a very similar but different problem. I have a 2004 Kia Optima which is having issues with the temperature or temperature gauge. I had a problem where the temp gauge would rise, but if you turn off the car and turn it right back on, the gauge reads normally. Then after a little while, it will rise again or sometimes it won't rise for several minutes.

I had the thermostat and temp cooling sensor changed. It worked great for almost 2 weeks. Then it started this pseudo overheating thing again. So, we changed out the temp cooling sensor and thermostat. When we pulled the thermostat this second time, it was stuck open. So, we thought, we had it fixed.

Unfortunately, it has been almost 2 weeks again and the problem has arrived once again.

I think something is either causing the temp sensor or the thermostat to go out. But I have no clue where to go from here.

I have read this and a couple of other threads, and noticed an issue with the AC refrigerant. I will attempt to see if turning on or off the AC causes a difference with the cooling reading.

Has anyone seen a problem where the gauge is reading that it is hot, but if you turn off the car and turn it immediately back on that the temp reads normal for a at least 45 seconds before it starts to move anywhere ( if not longer)? I have actually turned the car off and right back on before and it didn't show the car overheating for at least 20 minutes once.
my car is exaclly the same thing but do you notice when it starts to reads high does it feel like car is losing power ? and ac starts to blow warmer
 

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my car is exaclly the same thing but do you notice when it starts to reads high does it feel like car is losing power ? and ac starts to blow warmer
power loose is normal when car starts overheating.

where do you live?

if A/C blows not cold, look if A/C works fine. First pressure (over- or under-charged); then compressor and pressure switches, next move to radiator - is it clean, not bent, all the fins are straight, can air move through it?
the air has to pass A/C radiator first to reach coolant radiator. if A/C radiator gets hot (insufficient amount of R134a in A/C system = warm air instead of cold) then the air gets so hot that is not able to cool down coolant radiator = overheating.
do the fans work fine?

other things to look for are air/fuel ratio (lean will make engine overheat), spark plugs, air filter, oil and so on...




EDIT:

to check if it is really overheating you can try to listen to it (if it is you should hear some boiling....). Another thing - check all connectors. get any aftermarket sensor...
when it boils you should see steam coming out from the radiator cap (it would release excess of pressure)
 

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I live in salt lake city the tech. cant find any problem they say its a temp. gauge but I dont think thats the problem so if I am lossing power does that mean car really overheats not a faulty gauge A/C normally blows really cold but when the temp gauge starts to go up I feel like it's not as cold as when it'snt acting up yes I had the radiator flushed as I was reading the posts someone said to check the A/C HIGH PRESSURE and LOW PRESSURE pipes low pressure is cold but HIGH PRESSURE PIPE IS TOO HOT I dont know if that is normal I checked the radiator it looks clean and no bent ,fins are straigh spar plugs changed 3k mile ago air filter oil I do most of the routine maintanence any idea what could it be should I change the thermostat the water pump is the original one would that cause a problem? thermostat temp standart at part stores are 180 F should I get a lower temp so it opens before ?
 

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HIGH PRESSURE PIPE IS TOO HOT I dont know if that is normal I checked the radiator it looks clean and no bent ,fins are straigh spar plugs changed 3k mile ago air filter oil I do most of the routine maintanence any idea what could it be should I change the thermostat the water pump is the original one would that cause a problem? thermostat temp standart at part stores are 180 F should I get a lower temp so it opens before ?
high will be hot, its normal in hot air, but the thing is the radiator fan.
does the overheating happen in highway speeds or it happens ONLY in slow traffic (stop and go). If so, it may mean not enough heat is released to air from both radiators. In this case, there is nothing we can do. Sorry. It could be that KIA did not calculate that some cars will be used in temp over 110 F, so they need bigger radiators.
If A/C is fine, and pressures are all right, and without A/C being on coolant stays in normal range - dead end. The only thing you can do is to have an extra switch for radiator fan to make sure it is spinning all the time (or whenever it is overheating).

And YES, when it starts overheating you will feel loose of power and A/C will blow warmer air. A/C would be disabled by PCM or ECM in order to bring engine temp to normal.
 

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I'm back with an update/resolution on my overheating problem

I finally had to throw in the towel and get my mechanic to look at it...it ended up needing a new radiator (temp readings showed wide discrepancies in hot and cole temps located at different points within the radiator)...Car's been running for about 2 weeks in daily 90+ degree weather here in the Pacific Northwest with no overheating issues (gotta find some wood to knock on...)
Thanks again for all the suggestions
:cool:
 

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high will be hot, its normal in hot air, but the thing is the radiator fan.
does the overheating happen in highway speeds or it happens ONLY in slow traffic (stop and go). If so, it may mean not enough heat is released to air from both radiators. In this case, there is nothing we can do. Sorry. It could be that KIA did not calculate that some cars will be used in temp over 110 F, so they need bigger radiators.
If A/C is fine, and pressures are all right, and without A/C being on coolant stays in normal range - dead end. The only thing you can do is to have an extra switch for radiator fan to make sure it is spinning all the time (or whenever it is overheating).

And YES, when it starts overheating you will feel loose of power and A/C will blow warmer air. A/C would be disabled by PCM or ECM in order to bring engine temp to normal.
Yes it does that on highway with A/C on turning A/C brings it back to normal when the car was under warranty I had the same problem they replaced the thermostat like 3 years ago for a year it was fine but it came back so I wanted to see if the thermostat really works I filled up the spare tank with coolant and made the car overheat took the radiator cap off and the spare tank both but the water level was still the same even when I open the radiator cap and it spilled some out and I made the car overheat again I didnt notice coolant level dropped from spare tank so I am thinking its the thermostat when the A/c is off car is fine I shift gears on 5000 rpm never acts up but when I turn the A/C on then it suffers do you think my problem would be the thermostat or do you know if I can check that anyways? with old cars I use to take it off and put it in to the boiled water and see if it works but new cars arent like that I believe
 
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