2016 outback heating up when driving around 80mph and above

Guys need help my subbie outback 2016 2.5 is overheating when I drive above 90mph. The temp guage is normally on the middle but when I drive fast it starts to creep to the right side at the 3/4 close to the red zone. I have checked the radiator and have noticed that coolant is moving from the radiator to the reservoir tank after a drive. The car is not losing coolant, if I remove the reservoir tank and pour the coolant back into the radiator it fills the radiator and the reservoir tank remains with the quantity between the min and max. Is it a head gasket issue? Or thermostat or the radiator cap. The car is still new less than 40k miles. If i hook up an obd the coolant temp is around 109 degrees celcius when driving around 80mph. If I push it to 90 or 95mpg it goes to 110 degrees celcius. Thats when the temp gauge starts to move to the redline although i have not allowed it to reach the redline .Have removed the thermostat and drove it without but it still does the same.

You are concerned because the temp has gone up 1*??? Did you think it was going to run cooler when you pushed it harder?

do a hydrocarbon test on your coolant, report back the results.

 

I have driven all 3 of my Subaru at 80mph for extended periods of time and none of them ever changed temp gauge wise

Make sure your coolant is a 50/50 mix coolant/water.

do a hydrocarbon test on your coolant, report back the results.

 

I have driven all 3 of my Subaru at 80mph for extended periods of time and none of them ever changed temp gauge wise

 

the HC test was done with the blue liquid and it didnt even change colour, thus negative. Im now suspecting the radiator cap?

your radiator is partially clogged that is allowing it to cool sufficiently at low loads but at higher loads it is not enough.

 

I had the same problem with a Mercury Sable years ago; It would run fine but overheat on uphills.

 

but i would recommend replacement of just the rad cap to start since it is so cheap.

Hi, for start remove radiator cap when engine is cold, start the engine and look for any baubles. No baubles is good, baubles is head gasket. 2016 is new for radiator to be clogged. Also you could have air pocket in the cooling system if someone was draining and refilling coolant and did not know what he/she was doing. I also suggest removing radiator cap, reservoir cap with engine cold and run engine until cooling fans start to run or coolant starts to spill out from the radiator. This will remove all air pockets. Also do not forget to have heat on max and fans on 3-4 speed during this procedure. If the radiator cap was loosing pressure you would notice coolant around the cap area and on top of the radiator. Also any head gasket leaks would show up as steamy exhaust even when engine reaches operating temperature. Edited January 10, 2020 by aki334

Hi, for start remove radiator cap when engine is cold, start the engine and look for any baubles. No baubles is good, baubles is head gasket. 2016 is new for radiator to be clogged. Also you could have air pocket in the cooling system if someone was draining and refilling coolant and did not know what he/she was doing. I also suggest removing radiator cap, reservoir cap with engine cold and run engine until cooling fans start to run or coolant starts to spill out from the radiator. This will remove all air pockets. Also do not forget to have heat on max and fans on 3-4 speed during this procedure. If the radiator cap was loosing pressure you would notice coolant around the cap area and on top of the radiator. Also any head gasket leaks would show up as steamy exhaust even when engine reaches operating temperature.

I agree to a point but Subaru's tend not to show Steam out the exhaust.. My old school 2.5 blew a head gasket and as ling as I kept it out of the Higher RPM's and drove conservative it was cool. BUT once I got into the revs I would get a air pocket and the temp would rise and over heat.. Coolant would fill over flow bottle and once car would cool the engine would suck the coolant back out of the overfill bottle..

 

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The FB25 engine in a 2015-up Legacy/Outback is specifically designed with no coolant passages through the block/head interface. A "blown head gasket" cannot result in a coolant leak.

The FB25 engine in a 2015-up Legacy/Outback is specifically designed with no coolant passages through the block/head interface. A "blown head gasket" cannot result in a coolant leak.

 

so in this case how will you be able to verify if it has a blown head gasket?

so in this case how will you be able to verify if it has a blown head gasket?

Do a compression test. A blowdown/leakdown test is usually most accurate.

OK the speed limit in MI varies from 70-75 and I have on multiple occasions driven the car at 80-85 for hours on end and it never varied in temp readings. 2014 legacy with the same basic 2.5L will happily do those speeds all day long with the A/C on and the temps in the mid 90's.

 

2 things that will cause the issue you describe on this specific engine.

 

1. some blockage somewhere

2. water pump impeller failure

Edited January 14, 2020 by YeuEmMaiMai

Would a water pump fail below 40k miles. How do you test correct function of a water pump

not really a good way but you can use a infrared thermometer

can a water pump work only on low rpms and slip at higher rpms since I dont have overheating at low speeds

Any updates on this? Replacing the cap is cheap and easy.

 

Also, are you still under warranty?

You are concerned because the temp has gone up 1*??? Did you think it was going to run cooler when you pushed it harder?

 

 

Pay attention to the actual values, not the single degree rise. The temperatures he's noting are high, especially if he's noting these with the thermostat removed, as well...

can a water pump work only on low rpms and slip at higher rpms since I dont have overheating at low speeds

 

I would imagine that you would notice overheating at a stand-still as well as high road speeds if the water pump impeller has eroded away or broken-up. Neither is likely with such low mileage.

I replaced with a new cap car still runs hot I think the radiator is somehow blocked or not working efficiently so will buy a new radiator and see. I doubt its a head gasket because the car only runs hot when you drive fast

Where are you?

 

Has the cooling system ever been touched? Non-Subaru fluid used?

Hey,

check that the lower grill shutter or whatever is called (the one that automatically closes at high speed) is stuck in the closed position just an idea that came to my head.

thank you guys for the help and information, I have solved the problem , It was the RADIATOR, I just bought a new radiator,and changed now the car runs cooler never exceeding 93 degrees even if I drive at 100mph. I think the radiator was bloked inside maybe. I bought new radiator (DENSO) on AMAZON for about $80 and now the car behaves like it should. Surprised how a radiator would fail at less than 50k miles

...Surprised how a radiator would fail at less than 50k miles

 

 

Surprising for sure. Was there any possibility someone, at some time dumped in an additive, or added some non-OEM fluid?

thank you guys for the help and information, I have solved the problem , It was the RADIATOR, I just bought a new radiator,and changed now the car runs cooler never exceeding 93 degrees even if I drive at 100mph. I think the radiator was bloked inside maybe. I bought new radiator (DENSO) on AMAZON for about $80 and now the car behaves like it should. Surprised how a radiator would fail at less than 50k miles

So it was out of Warranty? I've been talking with my local independent Subi Mechanic about my cooling dystem since he changed my fluid and installed my Samco Hoses.. He said the Subaru Additive has been causing Radiator Issues like plugging them up So he doesn't use it.. Also for you do it yourself mechanics he recommends the Zerex Blue 50/50 Made for Asian Cars Specifically Subaru.. There is Red and Blue so make sure it says Subaru.. Also invest in a Burp kit it's a painless servicing system no spilled fluid..

 

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Edited February 9, 2020 by Grnlantern1
Added Photo

So it was out of Warranty? I've been talking with my local independent Subi Mechanic about my cooling dystem since he changed my fluid and installed my Samco Hoses.. He said the Subaru Additive has been causing Radiator Issues like plugging them up So he doesn't use it.. Also for you do it yourself mechanics he recommends the Zerex Blue 50/50 Made for Asian Cars Specifically Subaru.. There is Red and Blue so make sure it says Subaru.. Also invest in a Burp kit it's a painless servicing system no spilled fluid..

 

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yes it was out of warranty, bought it cheap on an auction , was previously in a fender bender accident, replaced right headlight , wing and bumper