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Discussion Starter · #1 ·
Hello everybody,

I am experiencing the following problem which started out of nowhere. When i start the engine and even when i drive, the engine temperature gauge shows no increase in temperature. If then, i switch off the engine and i keep the battery on i can straight see the temperature to increase to normal levels. If then i start the engine, the temperature gauge shows a rapid decrease of the temperature.

What could that be? Do you have any idea or experience with something similar? Thank you

Best regards
Charis
 

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2008 Accent 3 dr 5 sp manual; 2010 Genesis Coupe 2LT track 6 sp manual
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Sounds like the thermostat is stuck open.
 

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Discussion Starter · #3 ·
Hi and thank you for the response,

If the thermostat would be stuck open, could the heating system of the car function properly?

Best regards
Charis
 

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2008 Accent 3 dr 5 sp manual; 2010 Genesis Coupe 2LT track 6 sp manual
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You won't get much heat. Does the upper radiator hose get too hot to hold onto? It is full of coolant yes?
 

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Discussion Starter · #5 ·
It has coolant inside but it is not full.hot. Yes I will change the thermostat today to see if it gets better. Thanks again
 

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If the coolant is not completely full then air will be in the system. If the coolant temperature sender is in air and not coolant it will not read correctly.

If it is in air, and you turn off the engine, the coolant heats up and expands and may be covering the sensor then. That may explain the not reading when running but reading when you shut it off.

The radiator should always be completely full when the engine is dead cold, say sat over night. If it is not then there is some sort of a leak or the radiator cap is bad. Radiator cap can checked or may be easier to just replace it.
 

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Discussion Starter · #7 ·
So when the car is dead cold, the coolant should be on the top of the radiator cap that is located on the upper hose? Thanks
 

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Yes, there should be only coolant in the radiator when it is dead cold, there should be no air. Since there is air present, your temperature gauge is making strange readings or maybe damaged, or you may have overheated and done head damage. If the radiator is only partially full, then it has leaked out somehow and you should locate the source of the coolant loss and repair to prevent overheating. You have to keep the radiator full of coolant, and "burp" the system to fill. Burping requires running the car at idle with the radiator cap off for 1/2 hour to fully heat the motor. You will see you must add small amounts of coolant over time to achieve a full radiator. Once it is full, the water will get hot and start to spill out, that's when you put the cap on and cleanup.... job finish.
 

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If there is air in there that means it is loosing vacuum when it cools down. This vacuum would usually pull in the coolant into the radiator from the over flow tank as the engine cools down.

It doesn't take much of a leak and the leak may just be air and not coolant. The radiator cap is a usual cause if there is not any visible coolant leaks seen.
 

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Discussion Starter · #10 ·
The problem with the temperature is solved after the installation of the new thermostat.

The problem with the coolant remains as whenever the car is cooling down, the upper hose is getting full of air. Thank you very much for your help. It's already getting better the situation
 

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The air in the cooling system will work itself out after several heat/cool cycles. That is if everything is good and leak free. You can speed this up by opening the radiator when it is cold and topping it off.
 

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Discussion Starter · #12 ·
Thank you again very much. You are very helpful. I will try to do as you say. Now I am checking to buy some timing belt kit in order to change my old belts. Thanks
 

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If after several cooling cycles and the radiator is still taking coolant and the overflow tank is getting fuller then there is still a leak or problems. The coolant is getting pushed out when it heats up, but does not get sucked back in when cooling down so it is loosing the vacuum.
 
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