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Discussion Starter · #1 ·
2012 Subaru Outback 2.5L Premium 4 cylinder 109,000 miles

At about 97,000 miles, at local speed(idle to 35mph), the Engine temperature going up(from 196 to 223 degrees) and coolant coming out of the reservior.

So I did the following(All OEM parts):

1. Changed the radiator cap
2. Changed upper and lowe hoses
3. Changed Thermostate
4. Test the Engine Gasket and it is not leaking

It occurs at 99,000, 105,000, and Just yesterday, the same problem occurred at INN and OUT drive-thru, it was idling, and cool start to leaking from the coolant reservoir slowly. Engine temperature reaches 217 degrees. I shut the engine, rest for 20MINS. And drove home about 20 miles some local speed and some highway speed, no problem going home.

So far only happens about once in 1-2 month. As long as I refill the coolant, and it will go few thousand miles without overheatiing

I was told to replace Engine cooling fans since overheating only happens at low speed(idle to 35mph).

Any suggestions?

Thank you in advance,

Paul
 

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Outback 2011 3.6R Premium
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Have you checked the coolant level in the radiator as well as the overflow bottle?

I suspect you have a slow weep and your radiator level is dropping over a period of time.

The cooling system only holds around 6 quarts of coolant and the loss of half a quart can cause overheating problems.

When the engine is cool, check the coolant level in the radiator and overflow and top up as necessary. Recheck the level in the radiator and overflow every day before driving the vehicle and top up as necessary until the level stabilises. If the level continues to drop you have a leak that needs to be found and fixed.

Once the level stabilises check every week for a few weeks to ensure there are no further leaks.

Seagrass
 
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2012 Outback 2.5 Limited
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Agree on monitoring the level. We've had tiny but consistent coolant evaporation(?) since ours was new. You have to add a tiny amount every few months to keep the overflow bottle at the full mark when cold.

I'm assuming your overheat-at-idle was with AC running too which puts additional strain on the engine and heat through the condenser. And obviously with the coolant bypassing the cabin HVAC so no opportunity to transfer heat that way either. Summer weather can definitely be brutal to the cooling system.

Make sure both fans are working and that there's no obstructions. There's also a relay that can switch between low speed fan and high speed fan mode. If only low speed works that might not be sufficient to keep up with the heat when sitting idle without airflow.

The FSM calls for a bunch of checks using the SSM monitor tool, but it also has some checks you can do with a simple multimeter. Here are a couple to check for:

Check fuse #7 and fuse #22 to make sure they have continuity (use an ohm meter, not just visual inspection) and make sure you have power to the relays:

513614


And then there are these tests:

513611


513612


513613


Might also benefit from cleaning the fins with an evap/condenser cleaner solution, although be careful not to go with the strongest stuff as you don't want to etch any paint surfaces it might come in contact with. I've used Nu Brite diluted to the max dilution level (mildest solution mix) without issues. Apply, let sit for a few minutes, and rinse off with garden hose.

You've pretty much already done a drain-and-fill by means of replacing the lower radiator hose and thermostat, otherwise that would be a suggestion.

Given that it's NOT overheating on highway driving that should eliminate some possibilities like the water pump (a bad water pump would cause it to overheat regardless).
 

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Discussion Starter · #4 ·
Have you checked the coolant level in the radiator as well as the overflow bottle?

I suspect you have a slow weep and your radiator level is dropping over a period of time.

The cooling system only holds around 6 quarts of coolant and the loss of half a quart can cause overheating problems.

When the engine is cool, check the coolant level in the radiator and overflow and top up as necessary. Recheck the level in the radiator and overflow every day before driving the vehicle and top up as necessary until the level stabilises. If the level continues to drop you have a leak that needs to be found and fixed.

Once the level stabilises check every week for a few weeks to ensure there are no further leaks.

Seagrass
Have you checked the coolant level in the radiator as well as the overflow bottle?

I suspect you have a slow weep and your radiator level is dropping over a period of time.

The cooling system only holds around 6 quarts of coolant and the loss of half a quart can cause overheating problems.

When the engine is cool, check the coolant level in the radiator and overflow and top up as necessary. Recheck the level in the radiator and overflow every day before driving the vehicle and top up as necessary until the level stabilises. If the level continues to drop you have a leak that needs to be found and fixed.

Once the level stabilises check every week for a few weeks to ensure there are no further leaks.

Seagrass
Yes, the radiator coolant is low when it was overheating. I thought it all went to the reservoir,. I did check for the leak but it must be so small that it doesn't drip down to the ground. Thank you for your confirmation and suggestions.
 

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Discussion Starter · #5 ·
Agree on monitoring the level. We've had tiny but consistent coolant evaporation(?) since ours was new. You have to add a tiny amount every few months to keep the overflow bottle at the full mark when cold.

I'm assuming your overheat-at-idle was with AC running too which puts additional strain on the engine and heat through the condenser. And obviously with the coolant bypassing the cabin HVAC so no opportunity to transfer heat that way either. Summer weather can definitely be brutal to the cooling system.

Make sure both fans are working and that there's no obstructions. There's also a relay that can switch between low speed fan and high speed fan mode. If only low speed works that might not be sufficient to keep up with the heat when sitting idle without airflow.

The FSM calls for a bunch of checks using the SSM monitor tool, but it also has some checks you can do with a simple multimeter. Here are a couple to check for:

Check fuse #7 and fuse #22 to make sure they have continuity (use an ohm meter, not just visual inspection) and make sure you have power to the relays:

View attachment 513614

And then there are these tests:

View attachment 513611

View attachment 513612

View attachment 513613

Might also benefit from cleaning the fins with an evap/condenser cleaner solution, although be careful not to go with the strongest stuff as you don't want to etch any paint surfaces it might come in contact with. I've used Nu Brite diluted to the max dilution level (mildest solution mix) without issues. Apply, let sit for a few minutes, and rinse off with garden hose.

You've pretty much already done a drain-and-fill by means of replacing the lower radiator hose and thermostat, otherwise that would be a suggestion.

Given that it's NOT overheating on highway driving that should eliminate some possibilities like the water pump (a bad water pump would cause it to overheat regardless).
Both Engine fans do turn on when I turn on the AC. I just don't know how strong the fan should be blowing. I Will check the condition of the relay and fans with your provided instructions. Thank you so much for your help.
 

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2011 Outback 3.6R Premier w/206K miles.
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All excellent advice provided however I didn't see one thing mentioned: The radiator may be partially clogged and needs to be replaced.
 

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Seems like a fan/s issue. Maybe the high speed is not working, relay sticking intermittently, or the there might be a problem with a temp. sensor that controls the fans, not sure if it has a separate one from the ecu temp. sensor.
 

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2012 Outback 2.5 Limited
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not sure if it has a separate one from the ecu temp. sensor.
Looking at the FSM diagrams it looks like it's just one coolant temp sensor. The relays are controlled by the ECM based on the ECM receiving the temperature measurements.

513645


I know my old Corolla has a separate coolant temp switch that controls the fan relay, but that's probably the old way of doing it....
 

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Cool diagram, interesting circuit for the sub fan; looks like depending on if the main relay 2 is energized, sub fan is either grounded directly or run in series through main fan and they ground together, which I assume runs both fans at a slower speed.
 

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Discussion Starter · #10 ·
Thank you all for your suggestions and information. I took my Subaru in this morning. Going on a one-week road trip with this car so I can't take any chance of overheating. I Will update you on the finding.
 

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Discussion Starter · #11 ·
Just got word from the Subaru mechanic the head gasket is blown. $6,000 to replace it.
 

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Outback 2011 3.6R Premium
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Just got word from the Subaru mechanic the head gasket is blown. $6,000 to replace it.
What did they base this on?

The 2012 engine has multi layer steel head gaskets which are not prone to failure like the engines prior to 2011.

I fear your mechanic may have just “determined” it was head gaskets as this is a “known problem” with Subaru engines.

The quote figure of $6,000 is another sign something is wrong with the mechanic as this should cost between $1,500 and $2,000.

$6,000 is an exorbitant price.

It may be time for a second opinion.

Seagrass
 
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What did they base this on?

[ snip ]

It may be time for a second opinion.
I second this. Anytime major / expensive work is required a second opinion would be prudent. Especially when the symptoms of the problem, at least as those provided here, do not align. Many of the other suggestions make more sense (to me, a layman who has some basic mechanical knowledge). My 2005 had the same symptoms and it ended up being a plugged radiator (which is why I suggested it).
 

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2011 Outback Limited 2.5i/2018 Crosstrek limited
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Testing the gasket for leaks is not always going to work. When a HG went on our OB they did a bunch of tests including a presure test. They gave the car back saying they couldn’t find anything. On the way back home it started all over again. Let me just say the next phone call I had with them was rather testy. Not all tests will definitively be accurate.
 

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Discussion Starter · #18 ·
I went to Tokyo Automotive Repair - Subaru, Lexus, Hybrid and Toyota Auto Repair in Placentia Ca. $5600-6,200 is including everything when head gasket is replaced.

I just drove the car for 100miles, so far no overheating issue.

I guess it must be a small leak so it is holding up for now.

Anyone knows a good Subaru specialist anywhere between San Diego to Fresno, CA

I would like to replace the gasket for under $3000.

The car is in excellent condition.

Thank you,

paul
 

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2010 Outback 2.5 Prem
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Just this week, my radiator failed and blew my head gasket. This was on a road trip, my car is currently at a Subaru dealership in Boise, ID... 500 miles from where I live. $3300 for radiator and head gasket, which requires machining the aluminum surfaces (not sure if machining is required for all head gaskets). Price includes a ‘pity’ 15% discount. Not sure how $6000 gets justified.
 
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