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Discussion Starter #1 (Edited)
First, thanks to all contributors on this forum. After much research on here, I purchased a 2010 3.6r with 140,000 in December. I moved cross country with loaded car and had no issues at all.

Starting about 2 months ago I noticed when I was under sustained loads like gaining 1000 vertical at highway speed , my temp warning light would flash. Usually only briefly. It has begun to happen more regularly but never turned solid red and never any signs of overheating. In PNW so temps are 45-50 F usually.

I bought an OBD tool and now can view my coolant temp while driving for last week. Under normal conditions, like around town or highway speeds on flats, I see temp around 215-220 F. That seemed warm to me but some reading suggests probably normal. But I have noticed that slight hills will cause it to climb quickly to 230 and going to the big 1000 ft hill near town will push it to 240 and trigger my flashing red temp. light.

After reading on here I tried some easy things. I burped the coolant system in my steep driveway. That had no effect. Today I put in a new OEM t stat and oem radiator cap. The old stat was OEM and the coolant was clear and normal looking. The old stat opened in hot water test. Added new Subbie Blue coolant and burped again. Went to the big hill and got exact same performance :(
**EDIT forgot to mention fans seem to cycle normally.

Obviously I'm dreading a HG issue but I'm wondering if I have a clogged radiator or water pump issue perhaps. Any suggestions appreciated.

2010 Outback 3.6 145k
 

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Discussion Starter #2
In case anyone gets this from searching I thought I would update.

Tried everything that was suggested from the forums and nothing worked.

Just got back from mechanic and he says all signs point to head gasket.

Guess I Gambled and lost. Bought it 5000 miles ago ��


2010 3.6r with 140,000 miles.
 

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06 Outback 2.5i
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Wait a minute. What signs did the mechanic find? Or is he just saying "well, gee, it's overheating, and it's a subaru, so it must be a HG"

Do you see bubbles in the coolant overflow? Oil mixed with coolant and/or coolant mixed with oil?

If you monitor the temp, do you see temp spikes, or is it a steady rise in temp that goes down after the load (hill) is removed?

How old was the coolant before you changed it?

I would highly recommend thoro flush (amazon link). It and a new radiator saved my car with similar symptoms *AFTER* I replaced the HG, valves, and a cracked head.
 

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2019 Subaru Forester Premium, Crystal Black Silica, Pkg 15
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I would second a "combustion gases" check of the coolant to make sure it is, in fact, a HG problem.

The 3.6's are significantly more robust when it comes to the HG department, but any engine will have problems if too hot. Did you try flushing out everything rather than just a drain and fill?
 

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140,000 miles in a grassy buggy place. The radiator might just be packed full of dead bugs limiting air flow through the cooling vanes causing higher running temps.
 

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140,000 miles in a grassy buggy place. The radiator might just be packed full of dead bugs limiting air flow through the cooling vanes causing higher running temps.
That would be my thought. Sure sounds like not enough air flow through the radiator.
 

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2001 VDC/SC One of a Kind
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No codes on the ECM?

First

Next

Restriction in the radiator is a possibility. I doubt its a water pump issue at all. Could also be in the heater core.
Are both fans coming on?
I'm in agreement on trash in front of the condenser/radiator blocking air flow as a possibility.
Have the CATs checked for restriction. A possibility. Not all temperature issues are coolant or HG related. Sometimes when the exhaust is restricted the temps rise. Air in, Air out. If it can't push the air out, the engine load spikes and its like pulling a trailer. Going up hill just adds to it.

Have you noticed any difference in fuel economy?
 

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06 Outback 2.5i
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Are both fans working and at both speeds?

What temp do the fans start the low speed, and at what temp do the fans start the high speed?
 

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Discussion Starter #9
Update to my sad story. Two mechanics told me I had blown HG. The first one didn't want job. Second one kept it 2 days and said "diagnostics" including combustion gases in coolant pointed to HG.

I decided to buy a used engine with 60 k miles rather than rebuild. $3000 later I have exact same symptoms. ��

Before the shop I had confirmed normal operations of fans. Cleaned the radiator even though it looked clean. Replaced thermostat and radiator cap with OEM products. Drained and replaced coolant when replacing t-stat.

I also bypassed the heater core and saw no change in temperature patterns. Running 210 in easy driving, jumping to 240-50 on steep climbs)

I asked both mechanics to check radiator and both said it checked out.

I had not considered restricted cat, I figured that would throw a code. I think my scanner will give me temps on that.

I feel like an idiot for getting talked into this.

Going in Monday to discuss with shop.
 

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2018 Dark Blue Outback 3.6R Touring arrived 8/31/2017
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Update to my sad story. Two mechanics told me I had blown HG. The first one didn't want job. Second one kept it 2 days and said "diagnostics" including combustion gases in coolant pointed to HG.

I decided to buy a used engine with 60 k miles rather than rebuild. $3000 later I have exact same symptoms. ��

Before the shop I had confirmed normal operations of fans. Cleaned the radiator even though it looked clean. Replaced thermostat and radiator cap with OEM products. Drained and replaced coolant when replacing t-stat.

I also bypassed the heater core and saw no change in temperature patterns. Running 210 in easy driving, jumping to 240-50 on steep climbs)

I asked both mechanics to check radiator and both said it checked out.

I had not considered restricted cat, I figured that would throw a code. I think my scanner will give me temps on that.

I feel like an idiot for getting talked into this.

Going in Monday to discuss with shop.
My second car (77 Chrysler Cordoba) had problems with low power and trying to overheat, gave it to former roommate, who replaced the radiator (it was subpar) but that wasn’t enough: removed the cat, and when I saw him and the car next, we were doing 55mph through his huge apartment complex parking lot over the speed bumps. If I’d known it only needed thst much to be fixed, I might not have replaced it with the 93 Saturn.

Lesson learned, especially in regards to an older car. I was able to use that experience later when that car started showing signs (low power), quickly replaced cat on it.
 

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06 Outback 2.5i
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Update to my sad story. Two mechanics told me I had blown HG. The first one didn't want job. Second one kept it 2 days and said "diagnostics" including combustion gases in coolant pointed to HG.

I decided to buy a used engine with 60 k miles rather than rebuild. $3000 later I have exact same symptoms. ��

Before the shop I had confirmed normal operations of fans. Cleaned the radiator even though it looked clean. Replaced thermostat and radiator cap with OEM products. Drained and replaced coolant when replacing t-stat.

I also bypassed the heater core and saw no change in temperature patterns. Running 210 in easy driving, jumping to 240-50 on steep climbs)

I asked both mechanics to check radiator and both said it checked out.

I had not considered restricted cat, I figured that would throw a code. I think my scanner will give me temps on that.

I feel like an idiot for getting talked into this.

Going in Monday to discuss with shop.
Sorry to hear that..

What method did you use to clean your radiator?

What's the source of the used engine?

Have you re-verified the fan operation now that you had your old engine pulled out and a new one put in? Not that you should need the fans for around-town driving (except maybe stop lights on a hot day).
 

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Discussion Starter #12
Sorry to hear that..

What method did you use to clean your radiator?
I used compressed air at an oblique angle and the "jet " setting on a water hose. I picked out a few big bugs with a wooden skewer (big toothpick)

What's the source of the used engine?
I don't know exactly, hope to find out tomorrow. I figure I'm stuck with it either way.
Have you re-verified the fan operation now that you had your old engine pulled out and a new one put in? Not that you should need the fans for around-town driving (except maybe stop lights on a hot day).
I heard them cycle on/off in town and when idling in parking lot but I haven't checked temp details.

EDIT: They second, louder fan I see kicking on around 215. I think the other comes on earlier maybe 205?
 
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