Is my car REALLY Overheating? Hmmm....

That's the $1Mil question. How do you tell that your car is overheating. The temperature gauge in my car shoots up to the middle within 5 minutes of starting (seems normal), but after that it continues to go up and down, and up and down. I replaced the thermostat and the radiator because they needed replacing anyways and it didn't help. When the gauge goes up past half way, the fans kick in and starts blowing, but at the same time I loose heat in the car.

Had it checked at the mechanic and he says its not my head gasket (yikes!). Before I start throwing extra parts at the car, how do I know if my car is overheating? Are there any physical symptoms that I should see, or do I put my full trust in a gauge (that I had to replace before because of the same problem). Just want to know before I go throwing parts at the car.

Thanks,
Scott

Well since you arent getting heat in the car it seems like there is air in the system.I would try bleeding the system out and see what happens.

Thanks for the reply. The complete system was bleeded when the radiator was replaced. Bleed, flushed, back flushed. It gets heat as long as the fans stay off. But the when the needle passes the halfway mark and the fans come one, the heat begins to cool.

As for detecting if my car is really overheating, is there any visual confirmation that I should notice?

Thanks,
Scott

When the fans kick in the needle on the gauge goes down right?The heat shouldnt get cool when the fans kick in,which is why it sounds like a circulation problem.

No the gauge continues to rise. When its about 3/4 of the way to the top, then it just drops back slightly above half way. It'll stay there for maybe 5 minutes and shoot back up to about 5/8 of the way, then 6/8, then 7/8. It never touches the red, but it will stay at 7/8 of the way for a good 20 minutes. This all occurs within 30 minutes of driving the car.

Thanks,
Scott

Maybe it is the thermostat you put in it,some of them have higher temperatures then others.When the fans kick in it should cool down though,that is usually when the thermostat cracks open.

Doubt it. It was acting just like this before the thermostat changed. Im gonna try changing the Coolant Temperature Sensor and see if that does any good. Any other suggestion?

Thanks,
SCott

Before you throw any more money into this, read this thread -

https://www.thegalantcenter.org/showthread.php?t=41977

Also, I suppose you have more than 100K miles on the car?

There's 2 coolant temp sensor. 1 for the gauge and 1 for the ecu and fan controller.
If gauge is correlating to the fans kicking on I would look into coolant level or thermostat.
One way to check it is letting the car sit over night. Next morning open the radiator cap and top off coolant if needed.

Quote:

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Originally Posted by Gotti

There's 2 coolant temp sensor. 1 for the gauge and 1 for the ecu and fan controller.
If gauge is correlating to the fans kicking on I would look into coolant level or thermostat.
One way to check it is letting the car sit over night. Next morning open the radiator cap and top off coolant if needed.

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Are you sure there are two coolant temp sensors on the 8g? I was told there is only one, which is the brass one. For my car, I know for a fact that the car is actually over heating and there is nothing wrong with the gauge, because I have an ultraguage and have actually measured the temps in my engine bay manually.

Ok I have an ultra guage as well and there is 2 sensors if u disconnect the wire for the cluster you will still get a reading on the ultraguage,

My temp with the ultrgauge are 198/210

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Quote:

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Originally Posted by finald8ta

Ok I have an ultra guage as well and there is 2 sensors if u disconnect the wire for the cluster you will still get a reading on the ultraguage,

My temp with the ultrgauge are 198/210

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Yeah those are exactly around my ultraguage readings too, but I was told that it's not two different sensors, but just that the ultraguage is just reading the temp directly from the ECM, which also stores the temps to turn on and off the fans, control the coolant circulation etc. The brass one that I was talking about and the one you probably disconnected is the one that controls the guage on our guage cluster.

I'm now researching doing what g-spot said. I'm going to look at replacing the ECM relay. If that doesn't work either, I will think about replacing the ECM and seeing.

Quote:

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Originally Posted by tamim13

Yeah those are exactly around my ultraguage readings too, but I was told that it's not two different sensors, but just that the ultraguage is just reading the temp directly from the ECM, which also stores the temps to turn on and off the fans, control the coolant circulation etc. The brass one that I was talking about and the one you probably disconnected is the one that controls the guage on our guage cluster.

I'm now researching doing what g-spot said. I'm going to look at replacing the ECM relay. If that doesn't work either, I will think about replacing the ECM and seeing.

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If the brass one has one wire on it then its the guage only, ill get a pic up here shortly

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Ok Im Gona clear this up very easy, the 4g64 motors have two water temp sensors,

One controls the guage and the other goes to the ecu witch controls the fans


It's right below the cam sensor
Here some pics

Controls fans, ecu, ect
http://img.photobucket.com/albums/v5...a/IMAG0232.jpg

http://img.photobucket.com/albums/v5...a/IMAG0231.jpg
See the -40

That is all

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Yes, the one I replaced was the one in the 1st picture. The second one is inside the ECM?

the 1 in the first picture is for the ecu, the other 1 is located on top with 1 wire sticking out of it that 1 is for the gauge cluster, I will post a picture of that 1 later

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Which one did you disconnect, to cause your temps to drop to -40? The ECM one?

Quote:

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Originally Posted by tamim13

Which one did you disconnect, to cause your temps to drop to -40? The ECM one?

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The one in the first pic, the other is located on top of the near the injector on the water houseing near the tstat, that one controls the water temp guage in the cluster. Gime a min to get you a pic

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This is the sensor for the gauge cluster only
http://img.photobucket.com/albums/v5...a/IMAG0233.jpg
See that little guy in the center of the pic, my wire came loose trying to take a pic

You can see that it on top near the corner of the valve cover and under the wire harness

The ultraguage reads every sensor going to the ecu


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Thanks for the pictures. So your problem with overheating is still not fixed after replacing both sensors am I right?

My car is fine, I have had issues with over heating but I air in the system, my solution was to park the car on a hill let it run, add water when it was low and fill up the resivior check it the next day top it off and I was good, I check my fluids once a week and keep an eye on the temp,

Another trick was when my ultragauge went above 220 I was low on coolent and air was in the system, once I topped it off everything was normal,

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So you're saying the temps going between 198 - 210 is normal? I definitely do not feel my car is normal when it is reading 208.4 on the ultraguage. Did you read g-spot's post that I had linked to in my first reply?

I see it this way the sensor that controls the fans is in the block witch produces higher temps,
The one on top that goes to the cluster thats near the tstat witch will have a slightly lower reading,

Hell I could be wrong on what I said, Idk

most cars run at 180+ temps
The temp sensor for the cluster could be reading 180' and the one in the block can be at 200' for the ecu

I've been data logging a lot and the engine temp is at or near 200'
And its reading the sensor that's un the block


http://img.photobucket.com/albums/v5...a/IMAG0234.jpg

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Quote:

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Originally Posted by finald8ta

I see it this way the sensor that controls the fans is in the block witch produces higher temps,
The one on top that goes to the cluster thats near the tstat witch will have a slightly lower reading,

Hell I could be wrong on what I said, Idk

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You're totally right about this part. I've seen it happen, as I've been watching this behaviour happen, over and over again. The ultraguage shows it's higher, but the temp gauge is still low, and vice-versa. It has to be because they are closer to different sections of the engine, which heat up differently.

Either way, I'm pretty sure the one that I replaced is the one from the first picture, the ECM sensor (you don't happen to have the part number right?), as the one I got was brass and didn't have that one wire you mentioned, going to it. Since this hasn't fixed my problem, and I know I don't have air or coolant issues, my next step is the relay. I'm trying to figure out the correct part number for this. But I end up hitting all different part numbers. This weekend, I need to do some research.

Tbh I think you have air in your system, did you run the car with the heat on full blast and add coolent till you couldnt any more?

If your not getting heat that means your heater core is not full of coolent to pass threw and you have air in the system,

Run the car with the cap off turn the heat on and watch the radiator coolent drop, once that happens add more coolent, this will take up to 30-60 mins of doing then once you can't add anymore put the cap on, fill the resivor, take it for a drive for a few mins check to see if you have heat, head home let the car cool off, then check the fluids again,
I just went threw this awhile ago but I have a bad ratiator,


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^ what he said also make sure you have the green anti freeze i remember my car would reject the other brands like i had a coolant leak it would always evaporate or something but when i drain all the old out and just but green in everything was fine. also make sure you have the right mixture to endure this heat. dont want to much water itll cause boiling.

Thanx redhaze,

Also want to mention I'm running straight water right now,

I have my reasons so don't go and bash me, plan on doing a new waterpump timing kit in the next few weeks

No point in wasting 15$ in coolent.
So temps might be abit lower then 200' with antifreeze

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full operating temp is 212`

Wow, thanks everyone for all this information. I'm going to check for air in the system again and see what I can find.

Unfortunately, I failed at replacing the coolant temp sensor (fist pic). I couldnt get the 3/8 loose to do so. Just curious, what tools did you use to remove it? Also the manual says I have to drain the coolant first. Is this really necessary?

Thanks,
Scott

Quote:

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Originally Posted by finald8ta

Tbh I think you have air in your system, did you run the car with the heat on full blast and add coolent till you couldnt any more?

If your not getting heat that means your heater core is not full of coolent to pass threw and you have air in the system,

Run the car with the cap off turn the heat on and watch the radiator coolent drop, once that happens add more coolent, this will take up to 30-60 mins of doing then once you can't add anymore put the cap on, fill the resivor, take it for a drive for a few mins check to see if you have heat, head home let the car cool off, then check the fluids again,
I just went threw this awhile ago but I have a bad ratiator,


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Ok, couple of things on this suggestion.

1. I had read this suggestion of yours elsewhere and tried doing what you said, but when you open the radiator cap and run the engine with heat on full, the coolant comes up and out of the radiator... it does not go down, like you mentioned. So I gave up on the idea, as I did not want coolant all over my floor or engine. I also pressed on the upper hose and the coolant comes up, I believe it should not if there's air in the system.
2. I got my coolant flushed at the mitsu dealer, hoping that they would have the right tools/methods to get all the air out of the system. I told them to make sure there was no air at the end, so I guess they would have done that and there should be no air in the system. System still overheats to 208 or so.
3. Based on the other suggestion of only using green coolant, I've always and will always only use Mitsu coolant mixed with 50% distilled water.

Now, based on 1, and assuming 2 was not done right, am I supposed to allow the coolant to come out of the top of the radiator and just wait until it starts going down to follow your process?

Quote:

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Originally Posted by finald8ta

If the brass one has one wire on it then its the guage only, ill get a pic up here shortly

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How do I get to that brass bolt? I'm trying to use all my tools and have no space to remove the sensor?

Thanks,
Scott