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99 GF
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Discussion Starter #1
So I noticed the other day when I was driving for about 30 minutes may car was running a little warmer than usual on my Autometer gauge. It normal stays right around 180 always but it was running about 190. Lower radiator hose was cold and the header tank (95 EJ20G swap) was frothing when I revved the motor and let off. So the next day I drained the system, replaced the thermostat (Tama Ent. from Napa with jiggle hole on top), and burped it for quite a while jacked up with the heater on etc. Still its doing the same thing except its not getting frothy on the tank or bubbling now. When it's idling it will sit normal and not move forever when I drive it it goes between 180 and 190 on the gauge again and my bottom radiator hose is still cold. Im not loosing coolant, the overflow and header tank are normal it's blowing nice hot air and it's not running funny or anything. So it's not overheating it just seems to be a little more than normal which is concerning to me is all. Headgaskets have about 5/6k on them and pretty fresh Multi layer steel ones not the factory with a good surface job when they were done. I'm really not thinking a HG is the issue here but I guess I'm not sure what it is. Maybe I just have a really pesky air pocket that won't come out or maybe the water pump isn't circulating while driving it to keep it cool (didn't see any leaks around the water pump). Any suggestions you guys have would be appreciated. Also the Tstat I replaced it with was for an 02 wrx and yes my fans are operating it just seems as though the Thermostat isn't opening since the lower hose is cold while the upper one is hot.:help: :drunk:
 

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99 GF
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231 Posts
Discussion Starter #2
Hmmm anybody ever dealt with a blocked radiator? I'm running the stock N/A radiator with a gutted top cap and 1.1 bar cap on the header tank. I was just out trying to burp it again with the header tank cap off. at around 190* I checked the lower hose, it was cold and squishy but the whole top of the radiator was warm. Also I noticed if I squeezed in on the upper hose and held it, it would start to build pressure against my hand.
 

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I kill threads!
2000 Ver 6 STI - 1996 Gravel Express
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3,749 Posts
Pull off radiator, flush it with hose. If you want, can just flush the whole coolant system with a hose.
 

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99 GF
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Discussion Starter #5
Hmm its just been running cool forever then. Any idea when the stock wrx Tstat is supposed to open fully? Like i said that hose isn't warming at all, maybe Im not letting it get hot enough to open all the way. The part of it closest to the thermostat is warm but Im guessing thats due to the motor/manifolds waring it up.
 

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99 GF
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Discussion Starter #6
Well sorry all I'm just a paranoid weirdo after having one head gasket fail catastrophically on me on my last swapped car. Went out to burp again, let the car run longer and used a funnel this time. car got to be about 201-205 and BOOM Tstat opened all the way and a huge bubble came out, kicked the fans on and went to about 185 and stayed. guess I just wasn't letting it get hot enough to open fully. Again I apologize.
 

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2000 2.5RS/C BRP
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What are you apologizing for? It's nice to hear of a high-temp problem that was as simple as a bleed, not a failed headgasket or the like. I made a similar mistake when I last bled my coolant, I didn't add enough to the overflow bottle, so when the air purged it didn't completely refill the radiator. Then I had to do it all over again...
 

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99 GF
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Discussion Starter #8
Yeah over filled the over flow quite a bit to make sure that didn't happen. Like i said my last swap overheated very badly, warped heads and super effed up the block now I'm paranoid lol. I had a buddy telling me my car should never reach 195 and especially not 200 to open the stat fully so I was worried. After more reading including a manual for the wrx it's all quite normal. Crisis averted.
 

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2000 2.5RS/C BRP
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A lot of people don't realize that thermostats aren't just switches, but regulators. They START opening at the advertised temperature (180 on our cars, IIRC), but don't fully open until a higher temp (~200 on our cars, IIRC), and then vary the opening according to the coolant temp. Otherwise in winter, the temp would build and fall repeatedly as the coolant warmed, dumped into the cold radiator, cooled and shut the thermostat.

And yeah, my car runs at 190* +/-5. I've seen it get to 210, but never for long.
 
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