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2006 Impreza WRX Limited
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Discussion Starter · #1 ·
Back again with an overheating issue. I never ordered a radiator since it stopped overheating but here is the issue now and you guys can tell me what you think.

FIRST OFF:
no visible leaks
new thermostat
new radiator cap
new water pump

I pulled the thermostat and radiator and ran water through the system for a while to try and clean it out... I also ran water through the radiator to try and flush that as well.

I am getting BUBBLES :noes: in my overflow tank. I see no bubbles in the top of my radiator with the rad cap off but when it gets hot I start to see bubbles in the overflow tank. I heard bubbles in the top of the rad means head gaskets so but I don't think the same goes for overflow tank.

I did a leak down test and found no leak down on any of my cylinders. Next thing I will do is a compression test I guess...?

Or should I just say fuck it and order the radiator?

-Matt
 

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Meany Head
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Do the bubbles continue indefinitely? Or, does it bubble as your engine gets up to operating temp, then eventually stop bubbling? Because seeing "some" bubbles as your engine heats up is not abnormal. As the heat gets into the cooling system and causes expansion, thus pushing some air/coolant into the overflow. I'm sure you already knew that though. So, if the bubbles stop once your well up to temp, then I'd not worry about it.
 

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Discussion Starter · #3 ·
Thats the thing...they seem to just keep coming. I feel like its air in the system because last time it overheated I would just drive to heat it up, let it cool, and refill the radiator and after I did that for a few days it seemed to stop bubbling.

Thing is, I went to autocross and I overheated and I don't really have a good explanation as to why.
 

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Meany Head
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Damn dawg.. your havin' rottin luck with all this.
Did you ever do an exhaust sniffer test in your radiator?
When you overheated at the race, did your coolant level drop, thus causing the overheating problem?
 

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Discussion Starter · #5 ·
I never did the exhaust sniffer since the leakdown test showed no signs of an issue. I even did the leakdown test with the radiator cap off and there were NO BUBBLES in my radiator. I assume you know what a leakdown test is but for those who don't it just puts compressed air in your cylinders and shows you how much leaks out. I did 120 PSI.

My coolant level seems to drop and my car overheats. Weirdest part is when I overheat I open the rad cap slowly to release the pressure and water comes pouring out the overflow tank obviously...well the water ISN'T that hot.
 

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Discussion Starter · #6 ·
On the plus side, I got to autocross my friends Mitsubishi Starion Turbo and WOW that was a ton of fun to drive. On the 180 degree turns you can just drop it into first and bring the back end around and drive out of the turn. I was having more fun drifting than going for fast times :banana:

I have stock suspension plus a 20mm RSB and ran a 54 second time in my RS.

He has full coilovers/sway bars and my best was a 52 second, his best was a 53 second in his car.

I think I could have been faster than him if I had gotten to run my car the whole day. I only got 1 run with it and the second run I overheated so... I was faster than him in his own car though :rolleyes:
 

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Meany Head
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Hmm... I'm graspin' here now but... Lets see if we can eliminate more possibilities.

The leakdown test is ideal for bad valves or bad rings, but I'm not sure it would find a HG that was just leaking a tiny bit. 120psi is peanuts compared to the cyl pressure when the engine is running.

However, lets assume for a second that your coolant system is actually sealed, and has no external leaks. If your HG was letting exhaust/air past it into your cooling system, then that air should rise to the top of the cooling system and accumulate near the rad cap. Now, as the pressure continues to rise in the cooling system, it should push the air out the rad-cap into your overflow. Bubbles!! But, your coolant level should NOT drop very much. A little, yes, but not very much. My HG was an external leak, so my coolant did drop.

If you are finding that your loosing coolant to a significant enough level to cause overheating, then I think you still have a leak somewhere. The best way to find an external leak is with one of those florescent dye kits. Sometimes the leak is soooooo small, that it's invisible to the eye, and the coolant just vaporizes as soon as it comes out. The dye kit WILL find this leak.

If it's internal, well... lets eliminate EVERY possibility first.

P.S. Nice job out driving someone in their own car!! I let a friend co-drive mine at the AutoX early this year. She is a serious kick ass national level driver. I managed to keep in front my 0.2 seconds. Damn! Couldn't let someone out drive me in my own car! :p
 

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Discussion Starter · #8 ·
I will stop at autozone this afternoon and grab a dye kit. I didn't even think about trying that. Also I am running straight water right now since I didn't happen to have coolant on me to get home from autocross last night. Should I just put the dye kit in the water or should I add coolant as well? And I assume I will need a blacklight to find the leak?
 

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Meany Head
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It's been a long time since I used one of those kits. The one I picked up (we're talking 15+ years ago), came with everything you needed. The instructions were pretty clear too. Stop at Autozone, PepBoys, what ever, grab one off the shelf and have a read of how it works.

But, what I remember, you won't have to worry about antifreeze for use with the kit.
 

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i had this happen to me, and it was my radiator. Keep in mind i replaced everything wp/tstat/hoses/HC/temp sensor

and it was the radiator.

either way, i know my cooling system works right right?
 

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Discussion Starter · #11 ·
I think I will call radiator barn and just get a radiator. At 100k miles I guess it doesn't hurt to replace anyways...
 

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94L
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Do a cooling system pressure test after the thermostat is opened ;)
You need sorta like a hand pump with gauge... should have those in auto zone..
 

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94L
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If the pressure doesnt drop, guess you can try a new rad.
But if it does with thermostat opened, its most likely your headgaskets!
I think those rs's had those problems! and if you get headgaskets, get the 3pl layer once from the dealer! Heard they are a bit thicker but are much more reliable!
 

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Discussion Starter · #14 ·
I am running new HG's. Replaced about 4k miles ago. Checked the torque and they are torque correctly. Who knows...
 

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hmm... cracked block or head perhaps? <----- very doubtfully!!!
Since its not an external leak and it bubbles only when hot (thermostat opened, coolant flows) it means that there is most likely an issue in the motor..
 

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Discussion Starter · #16 ·
boo :curse:
 

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Discussion Starter · #18 ·
i wasn't boo-ing you... i was boo-ing my engine. haha
 
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