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Old 09-07-2020, 03:06 PM   #1
855T
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Default Overheat on freeway

2010 WRX, ~70k miles, on a Stage 1 OTS tune from Cobb, timing belt + thermostat + water pump + radiator hoses + radiator replaced about 6 months ago.

It's been hot af in LA lately. I was averaging about 80 on the freeway a couple weeks ago and noticed the A/C cut out, checked the engine temp gauge, and saw it was about 3/4 of the way to H. Turned off the A/C, slowed down, and turned on the heater, got it back to mid-gauge in maybe 2 minutes. At the time, the external temperature gauge showed 108 F.

Yesterday, closer to 115 outside, going 70 and saw the gauge start to creep up, so I killed the A/C - wasn't enough. Again, turned on the heater, temp dropped right back down again.

No signs of coolant leakage, oil looks and smells like oil, coolant looks and smells like coolant. It is, however, green and not Subaru Super.

People live in Arizona, so I assume this is not typical behavior for this car. I'm gonna hassle the shop that did the work, but anyone have a guess as to what's most likely? Failure to burp the system effectively? Bad coolant or coolant ratio? Thermostat? Effing head gaskets?
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Old 09-07-2020, 05:51 PM   #2
scoobyfast
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Have you logged coolant temps on the accessport to confirm the temps are indeed excessive? Are the fans kicking on? They should turn on at 205 deg.
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Old 09-07-2020, 08:50 PM   #3
855T
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Ran a quick log today...I saw 205 on the freeway but wasnít driving very long and itís close to 20 degrees cooler today. Iíll try and get a better log when it gets warmer.

Whatís a reasonable max? 210?
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Old 09-08-2020, 09:31 AM   #4
BlackFighter
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Check for air in your coolant lines.
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Old 09-08-2020, 12:46 PM   #5
855T
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I'll try a burp...a funnel is arriving tonight.
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Old 09-08-2020, 12:50 PM   #6
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Don't need a funnel. Just open your reservoir tank and squeeze the large curved Radiator Hose a few time. If there is air you should see/hear it bubble out in the reservoir tank. When you squeeze, just keep a eye on the tank for the coolant not top over flow. This hose. Not my pic. Keep in mind to do this with your eng off.

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Old 09-08-2020, 01:06 PM   #7
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Bad rad caps can cause some pretty funky cooling system issues, like what you're experiencing, and are a service item many people forget.

IIRC, Turbo tank is 108kpa (or ~1bar) and rad cap is is like 137kpa (or 1.3bar).
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Old 09-08-2020, 01:40 PM   #8
855T
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I'll give the hose a squeeze. The caps (rad and expansion tank) are new as well, but are cheap enough to try replacing.
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Old 09-08-2020, 06:21 PM   #9
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No obvious air on the hose squeeze. I'll try with the car running and the funnel in place, as well.
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Old 09-09-2020, 09:24 AM   #10
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Did this happen before you changed the thermostat?
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Old 09-09-2020, 12:23 PM   #11
855T
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I never saw it before the cooling system was overhauled. Doesn't mean it didn't happen, but I'm fairly confident this is a new problem.

I ran a longish datalog last night - coolant temps as high as 207 during sustained cruise ~85 mph over 15 miles or so.
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Old 09-09-2020, 01:19 PM   #12
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Why was the coolant system overhauled? I would check, maybe change, the thermostat again and reflush with new coolant. Why did you change your water pump at 70k? Was it changed to a OEM one or upgraded to a different model? Check the Radiator fins to make sure that there is nothing stuck in them preventing air from going through. Why was the radiator changed? Was there a issue or did you upgrade it to a after market?

Last edited by BlackFighter; 09-09-2020 at 01:25 PM.
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Old 09-09-2020, 01:44 PM   #13
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make sure your caps are on the correct positions...the round one on the radiator the oval on the upper one
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Old 09-09-2020, 02:29 PM   #14
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Caps are in the right spot.

Car was due for a timing belt and needed hoses, so I had them do the water pump (OE) as well, and they recommended an OE replacement radiator given that everything else was being replaced.

Thermostat seems most likely at this point.
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Old 09-09-2020, 03:08 PM   #15
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Well first thing first the shop BSed you in to changing parts that were perfectly fine. Unless the radiator is leaking or damaged there was no reason to replace it. Especially at 70k miles. Was the radiator a dealer part or a OE part from autozone? OE does not always mean it comes straight from the dealer. It just mean that the specs are the same as the dealer. Was this done at the dealer?

At this point if everything is fine with the coolant system and you can't fix the problem I would just take it back to the shop. Tell them:

" Look, before you guys touched the car the cooling system was fine, as soon as i picked it up after you, it started to have problems, WTF."

If this was all done 6 months ago then going back to the shop will be a waist of time. But if it was like a few days back or last week then you might have a chance. Lets just hope the shop owners son did not take your car out for a "test" drive and blew your head gasket. This is why i always record my mileages when giving any car to a shop. Any smoke out of the exhaust? Any sweet smells?
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Old 09-09-2020, 08:28 PM   #16
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^^^^^^this

Shop worked on cooling system.....they need to fix
Period.
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Old 09-09-2020, 08:31 PM   #17
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IMO
It’s a bubble
Now mind you I have 05, but one time
I had to park on inclined driveway, put front tires on ramps, ran can 20+ minutes while squeezing upper rad hose.
Finally did the trick
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Old 09-12-2020, 01:00 AM   #18
855T
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https://i.imgur.com/hN0ZDuJ.png
^ pic of coolant temp plot from datalog, shaded blue area is freeway cruise


It's gotta be the thermostat. Running 205 on the freeway seems too hot. We might get another hot day to pull data, but everything about this seems like a thermostat that's not opening fully.

Last edited by 855T; 09-12-2020 at 01:48 AM.
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Old 09-12-2020, 02:34 PM   #19
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Quote:
Originally Posted by 855T View Post
Ran a quick log today...I saw 205 on the freeway but wasnít driving very long and itís close to 20 degrees cooler today. Iíll try and get a better log when it gets warmer.

Whatís a reasonable max? 210?
make sure you have enough water in system. I had a over heating problem due to that very problem, put some water in the system and it went away
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