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Thermostat sticking

1632 Views 11 Replies 5 Participants Last post by  Hal H
Ok so bout 2 years ago I put STOP LEAK in my 2012 Dodge Challenger because I had a hole in the radiator. I replaced the radiator and now my car is running hot... i have replaced the thermostat 3x and have flushed it and my car still runs hot. The antifreeze is being pushed up in the reservoir and my needle goes back in forth. Someone please help me!!!! I think it’s the stop leak clogging my radiator and causing my thermostat to stick. What can I do to stop this??? I just paid my car off!
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Stop Leak is never a good way to go, but it did it's job until you replaced the radiator. Is this another Mopar radiator, or after market? Did you do the swap yourself, or have a shop do it? I'm just wondering if you have air pockets in the system causing this issue?
 
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Is the thermostat installed correctly? The little tip up and the small hole in the 12 o'clock position? These cars are a bear to burp the air out, could be an air pocket.
 

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Discussion Starter · #4 ·
Stop Leak is never a good way to go, but it did it's job until you replaced the radiator. Is this another Mopar radiator, or after market? Did you do the swap yourself, or have a shop do it? I'm just wondering if you have air pockets in the system causing this issue?
Hello! It’s an after market. And I had a friend replace it for me. Also I notice my hose keeps getting hard. The only way I can squeeze it is when I release the pressure from the reservoir when it’s running hot.
 

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Discussion Starter · #5 ·
Is the thermostat installed correctly? The little tip up and the small hole in the 12 o'clock position? These cars are a bear to burp the air out, could be an air pocket.
Hmmm that’s a good question! It drove good for 2 weeks then started back heating up. The hose keeps getting hard which makes it hard for me to squeeze but once I release pressure from the reservoir, I’m able to squeeze it again. I am so confused as to why it’s doing this.... and my thermostat needle goes back and forth which has us thinking it’s sticking
 

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It sounds like air in the system.
 
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Do you see a small plug in the top of the water pump. Likely uses an Allen wrench. Remove that plug and fill the resevoir until coolant comes out the hole. Put the plug back in, start th3 car and turn the heat on high.
 

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Discussion Starter · #9 ·
Ok seriously... someone please tell me what could be making my SXT keep running hot???
I put stop leak in bout 3 years ago because of a hole being in the radiator...
I have replaced the radiator since and changes my thermostat 3x for sticking....
There is no cracked head! Thank God
But something is causing the antifreeze to be pushed back in the reservoir.
Some one please help me?
They have bleed the line, flushed it, I don’t know what is going on.
 

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Did the person replacing it use the correct coolant? If they used the "old green" antifreeze then you may have a completely clogged up system from the coolants mixing.
 

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The heater core may be clogged up from the prior stop leak. Try flushing it out.
 

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another step is also check the coolant to make sure there is not presence of carbon monoxide.

If there is, that's a sign of a head gasket leaking. Combustion gases will superheat coolant and make it boil over.

If any air was purged out of the system, then there might be something restricting flow or there's an issue with the water pump
 
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