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2006 Impreza WRX Limited
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Discussion Starter · #1 ·
Well I am still having an overheating problem. I read the whole "Everything you need to know about your cooling system thread" and even tried replacing stuff...but I am still having an issue for some reason.

Symptoms
I fill up my radiator to full and leave the cap off. Start the car and let it burp and get the air bubbles out. Then I fill it up to the top again and put the cap on. Then I drive to work and it is fine. The temperature is rock solid the whole 20 minute drive down the highway. As soon as I pull off the exit I can see my temp start to rise. My work is maybe 500 feet from the exit and the temp is to 3/4 by the time I get there. Luckily I haven't let the temp get TOO hot.

I replaced:
Radiator cap (yesterday)
Thermostat (today)
Water pump (4k miles ago)
Head Gaskets (4k miles ago)

I checked:
radiator (flushed it out and water flows through it)
fans (are turning on normally)
pulled the whole radiator area apart and checked for leaks

I really need help guys. I can't do this every day before and after work. I have pulled everything apart and even put new parts in but I can't seem to figure this out. I can't find any external leaks anywhere but I am still having overheating issues. My exhaust DOES NOT smell like coolant, there is no coolant in my oil, or oil in my coolant. I don't see any crust around my head gasket seal, and my heat works fine. I also DO NOT get a green mist on the wind shield when I use my defrost. Like I said I have read that whole thread and searched google for whatever I can find but I have come up with nothing. I do not want to bring it to a mechanic because they will tell me a list of other things that need to be changed. I have an exhaust and cams so my CEL is on and they will think I need 02 sensors and cats but I don't...

Thanks in advance,
Matt
 

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You say you replaced the thermostat today... before or after the drive to work? I'm not trying to be condescending just wanted a clearer picture. What did you fill the system with and what are the temps like? Also you said it was an interstate run and not stop and go right.
 

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Discussion Starter · #3 ·
I replaced it before I drove to work.
I filled the system with the regular Autozone special coolant. I know people say it can be bad for the radiator but my RAD seems to be flowing fine and I have been using it as long as I can remember.
The temp gauge stays just about halfway right when I fill it. It runs good and temps are solid. After a long drive on the highway it all goes into the overflow tank and my temps start rising.
 

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Discussion Starter · #5 ·

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Damn. There has to be a block in the system somewhere. That's the only thing that still make any sense. Especially since its coolant not water and it all goes into the overflow tank.
 

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Discussion Starter · #7 ·
I am gonna let the car cool for a bit then I will go out and see if it flows through my heater core okay... I don't know where else the blockage could be...
 

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2001 A.W. L
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pop off the timing belt inspection cover, does you belt look ok?

You say you did the headgaskets? Did you follow the subaru procedure for torquing down the head bolts?

You are mixing the coolant 50/50 with water right (remember to only do this if you are NOT buying premixed)

Try burping the coolant again, sometimes those air pockets can be tricky little bastards.

check the hose that leads from the coolant resivor to your rad, see if it is clogged
 

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Discussion Starter · #10 ·

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a long shot, but i'm guessing it may have something to do with the most recently installed product..the thermostat? Warm it up after a cold start, and feel the temp of both hoses. 1 is hot n the other isn't it could be a thermo issue.
 

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I honestly have no idea if you could tell and I couldn't tell you which ones are and which are (such as auto zone vs advance vs subaru oem). But I was wondering if maybe the new one failed somehow and if it's not failsafe they can fail closed, which would prevent your fans from coming on.

Although in retrospect that doesn't explain the full overflow tank.
 

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2001 A.W. L
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What do you mean? Like a "NORMALLY OPEN" one?

How do I tell?
Did you use an OEM one?

you can check to make sure it is working by putting it in water and boiling it.. you will see it open. Also you put it in the right way right? spring up
 

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Discussion Starter · #14 ·
pop off the timing belt inspection cover, does you belt look ok?

You say you did the headgaskets? Did you follow the subaru procedure for torquing down the head bolts?

You are mixing the coolant 50/50 with water right (remember to only do this if you are NOT buying premixed)

Try burping the coolant again, sometimes those air pockets can be tricky little bastards.

check the hose that leads from the coolant resivor to your rad, see if it is clogged
The timing belt looks fine. It is a genuine Subaru belt so I would hope it would be.

When I did the headgaskets I followed the Subaru procedure as close as possible. I had a little trouble with the 22 ft/lbs or whatever because my torque wrench didn't go that low but I did it as good as possible.

I wouldn't say its an EXACT 50/50 mix but I mean...does it really need to be perfect? I poured about half into an empty coolant bottle and then filled them both up the rest of the way with water so it should be close...

What is the best way to burp the system?

The line that goes to the overflow tank? It is flowing just fine. But let me know if that wasn't what you meant.
 

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Discussion Starter · #15 ·
a long shot, but i'm guessing it may have something to do with the most recently installed product..the thermostat? Warm it up after a cold start, and feel the temp of both hoses. 1 is hot n the other isn't it could be a thermo issue.
Well the car started overheating so I then replaced the thermostat... I am gonna try boiling one when I get home today and see what happens.
 

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I guess that begs the question are you're fans coming on? That would tell you if the thermo is bad or the boiling water thing... That sounds neater to get to see it work.
 

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Discussion Starter · #18 ·
NOT AN OEM THERMOSTAT

It was NAPA's best one that they had. I put it in with the spring facing UP into the waterpump.

Also the overheating happens on both the old and new thermostat so maybe they are BOTH failed closed?

There was a LOT of coolant behind the old thermostat when I pulled it out though...I got soaked.
 

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Discussion Starter · #19 ·
Matt, if you need a ride at all, let me know. PM me if you need to reach me.
Thanks. :) Good to know there are people around that can lend me a hand.
 
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