2008 Aveo Overheating Issues

Hi guys, new to the forum here. My younger sister has a 2008 Aveo automatic transmission. It is the base model with manual door locks and windows. Anyways the car was working fine until it started getting real cold outside here in Chicago. She came to me and complained that her heater was not blowing hot air. Upon inspecting, I realized the thermostat was stuck open and the car wouldn't warm up to regular operating temp. I replaced the thermostat, and strange thing, there was no radiator cap. Just the reservoir. So i filled the coolant through the reservoir and "burped" the system let the car run until no more bubbles popped up. Took it for a test drive and everything checked out.

Next day she came back and told me that the heater was a bit too hot and when she shuts it off, the car starts over heating. So, I checked the fan which is working. I had replaced the thermostat with the housing as well so both are new. I went ahead and replaced the cap on the reservoir, made sure to try and burp it out again and let the car run for a while idling it wouldn't over heat. But when you drive it with the heater off, the car starts over heating even though the fan is working. Just FYI i used the dex-cool coolant which autozone suggested was the one for the car. I have tried everything as far as my knowledge goes. One thing I noticed, the hose coming from the thermostat is hot. The hose on the lower side of the radiator is cold. I dont know if that is normal. But please point me in the right direction. I want the mechanic to be the last option.

Quote:

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Originally Posted by siddiqim

... So i filled the coolant through the reservoir and "burped" the system let the car run until no more bubbles popped up. ....

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Did you set the heater to high, and run the blower full blast while doing this?

Quote:

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Originally Posted by avguy

Did you set the heater to high, and run the blower full blast while doing this?

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Yes the level went down and I added more coolant

If the air has been purged correctly, then it would seem that the most recent problem is related to the new T-stat.

If the lower hose is always cold, you most likely have one of two problems, blocked radiator or your coolant wasn't mixed right and had too much water, which allowed ice to form in the radiator or lower hose. I would recommend draining it out, preferably in a semi warm garage so nothing is near freezing, which will let you drain as much fluid out as possible. Then replace with new 50/50 premixed anti freeze. The hose from the thermostat will be hot once the engine warms up to operating temp, the lower hose should be too after that. If it's only starting to overheat after the interior heat is turned off, especially since you said the heat is so high temp, it sounds like the heater core is acting as the radiator and your actual radiator is not getting flow through it.

Any updates to the car?


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