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Discussion Starter #1 (Edited by Moderator)
I have a 02 Outback w/2.5L. I bought this car from a friend who brought it to Colorado from Arizona. He said he did the heads and afterwards the temp gauge kept reading in the red so he took out the thermostat and it stopped. Well, I bought it thinking a thermostat and new coolant temp sensor would fix it. But it didn't. Now it is actually overheating, the heater takes forever to get hot and goes back to cold. Plus the lower radiator hose stays cool. If anyone has any idea what may be going on, please help!
 

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I have a 02 Outback w/2.5L. I bought this car from a friend who brought it to Colorado from Arizona. He said he did the heads and afterwards the temp gauge kept reading in the red so he took out the thermostat and it stopped. Well, I bought it thinking a thermostat and new coolant temp sensor would fix it. But it didn't. Now it is actually overheating, the heater takes forever to get hot and goes back to cold. Plus the lower radiator hose stays cool. If anyone has any idea what may be going on, please help!
Are you sure all the air is out of the system?


 

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If the lower radiator hose is staying cold the thermostat is not operating Which could be due to having air around the thermostat.

The heater running hot then cold is another symptom that you have air in the system.

What brand of thermostat did you use, if not Subaru that may be your problem.

These engines are not always easy to “burp” as the air can get blocked behind the thermostat, not allowing it to open and causing overheating.

I always choose to drill an additional 4mm hole in the thermostat to allow the air to escape easier.

Seagrass
 

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Discussion Starter #5
If the lower radiator hose is staying cold the thermostat is not operating Which could be due to having air around the thermostat.

The heater running hot then cold is another symptom that you have air in the system.

What brand of thermostat did you use, if not Subaru that may be your problem.

These engines are not always easy to “burp” as the air can get blocked behind the thermostat, not allowing it to open and causing overheating.

I always choose to drill an additional 4mm hole in the thermostat to allow the air to escape easier.

Seagrass
I did buy the thermostat at Autozone. So I will call the dealership in the morning. Thank you
 

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2001 VDC/SC One of a Kind
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You could also check Advance/Carquest for a Mahle, Beck Arnley, or, XAct stat. The thermostat is a "beafy" design compared to the MotoRad you got from Auto Crap.

There's also a chance the head gasket repair wasn't performed correctly. If the heads and block weren't cleaned, or the heads torqued down correctly, they'll leak allowing for a coolant breech.
 

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Discussion Starter #7
So, I have been burping this for almost 2 hours now and still seem to be getting air bubbles. Thermostat appears to be working, lower hose is hot now. But still isn't blowing hot air from the heater and keeps it keeps running hot.
 

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you could have two separate issues where your heater core is blocked and your HG is leaking hence the bubbles after 2 hours of burping.

I'd be taking the car back to your "buddy" with a bunch fo Q's for him
 

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Discussion Starter #11
you could have two separate issues where your heater core is blocked and your HG is leaking hence the bubbles after 2 hours of burping.

I'd be taking the car back to your "buddy" with a bunch fo Q's for him
The heater is now blowing hotter air but not as it should be. And the temp gauge is going almost down to where it belongs after the fans run but they are not kicking on until it's in the red.
 

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For now you have nothing to lose by continuing to burp air. Once the engine cools down enough for the fans to stop blowing, you could try revving the engine to increase coolant flow and see if it purges more air. Do you have evidence that coolant is actually flowing, or do you think the heat is travelling mainly by conduction and convection?
 

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Discussion Starter #13
For now you have nothing to lose by continuing to burp air. Once the engine cools down enough for the fans to stop blowing, you could try revving the engine to increase coolant flow and see if it purges more air. Do you have evidence that coolant is actually flowing, or do you think the heat is travelling mainly by conduction and convection?
That's kinda the way I see it myself.... You can definitely tell when the thermostat opens and closes.
 

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Discussion Starter #15
As the air bubbles out, are you needing to replenish the coolant in the funnel, or is it seemingly bubbling but no additional coolant is going in?
It's taking a little bit, like about 15ml or less. But the last couple times it needed none.
 

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If the radiator isn't accepting more coolant, yet air keeps coming out, it's concerning.

If you were to shut the engine off, replace the radiator cap, and watch the coolant overflow, have you determined that bubbles aren't being blown into the overflow tank?
 

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Did you raise the front of the car a foot or so? That helps a lot in burping the heater core.
 

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Discussion Starter #18
If the radiator isn't accepting more coolant, yet air keeps coming out, it's concerning.

If you were to shut the engine off, replace the radiator cap, and watch the coolant overflow, have you determined that bubbles aren't being blown into the overflow tank?
This I have not tried. Now I have put the cap on and let it run through the fans kicking on a couple times and did not notice any bubbles then.
 
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