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Discussion Starter #1
Wife's ride is a 2015 Forester 2.5i with the CVT. We use it for road trips, mostly around the southwest. Sometimes offroad, but often in the heat.

Last trip, water temp got up to 247°F while driving for just a few minutes; I didn't even think I was pushing it that hard.

I have an all aluminum radiator in my WRX, and I can't get heat into the car in the winter to save my life, it's so efficient at cooling.

But I can't seem to find anything available that's all aluminum for her car.

Couple of questions then:

Is there anything that's close that might work with a few minor modifications?
Is there a significant difference between the FB25 radiator, and what's in, or is available for the XT?
Is there anything available for the XT that might work?
Uhh.. custom radiator?

I can't fathom that running that hot is good for long-term life of heads, and seals, etc.
 
2017 2.5i Fozy CVT
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Wife's ride is a 2015 Forester 2.5i with the CVT. We use it for road trips, mostly around the southwest. Sometimes offroad, but often in the heat.

Last trip, water temp got up to 247°F while driving for just a few minutes; I didn't even think I was pushing it that hard.

I have an all aluminum radiator in my WRX, and I can't get heat into the car in the winter to save my life, it's so efficient at cooling.

But I can't seem to find anything available that's all aluminum for her car.

Couple of questions then:

Is there anything that's close that might work with a few minor modifications?
Is there a significant difference between the FB25 radiator, and what's in, or is available for the XT?
Is there anything available for the XT that might work?
Uhh.. custom radiator?

I can't fathom that running that hot is good for long-term life of heads, and seals, etc.
Has the coolant been changed and topped up? If no then make it so before changing the radiator . Were you towing?
 
2017 2.5i Fozy CVT
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I have an all aluminum radiator in my WRX, and I can't get heat into the car in the winter to save my life, it's so efficient at cooling.
Something is wrong with you heater core or the valve that let's coolant into it.How old is that coolant?
 

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Discussion Starter #4
Has the coolant been changed and topped up? If no then make it so before changing the radiator . Were you towing?
Not towing. It was warm outside, and I was cruising with a car full of kids and luggage to Grandma's. Going up big hills ~75mph... it was early in the morning, but it was still 85 degrees out. Coolant level was topped off, thermostat cycled, and the overflow was half full before we left. Fresh oil change.
 

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Discussion Starter #5
Something is wrong with you heater core or the valve that let's coolant into it.How old is that coolant?
That radiator about doubles the coolant volume. The WRX just doesn't get hot with that radiator. Coolant was new when I installed the radiator this winter. Not ruling out something wrong with the heater core, but the point is I no longer worry about the engine getting hot. I live in Southern CA, so I'm not so worried about heating the cabin.
 
2017 2.5i Fozy CVT
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More to the point, would an Aluminum radiator for an XT fit?
I don't know, but I think it is an overpriced bandaid for whatever is causing the overheating. Put money into a pressure test and other diagnostics. It should not overheat like that if the Tstat is good, cap holds pressure and coolant mix is proper and of a sufficient amount.
 

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Discussion Starter #9
Total miles on ODO , coolant and CvT fluid is?
78k. Coolant is Prestone Ethylene Glycol full strength with distilled water in equal measure, and the system had been drained of the OE Super coolant. I haven't had CVT serviced or fluid changed (but it's on my list). I do have larger tires on it (225/65 17). I never got an overheat light, but I'm certain that 247 is too warm.
 
2017 2.5i Fozy CVT
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I would put the CVT SERVICE,,,DRAINFILL at the top of your list and radiator change at the bottom . What the cause of the hot coolant could be... I would be inclined to bet on the CVT since you have serviced the coolant.
Being that Suby has extended the warranty on the CVT to 100000 miles ,and you experienced overheating under mild conditions ,I would file this under "problem" worthy of factory service.

Did a scangauge give you the coolant temp? It can also give the ATF temp, as well..

It could be that your betters is driving it like she stole it-well before it warms up in the morning. Can't hurt to baby it for the first 3-4 miles.
FWIW, I have had 2 drain [email protected] 30 k mile intervals....70 k miles on odo now.
 

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2015 Forester 2.5i Limited CVT
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78k. Coolant is Prestone Ethylene Glycol full strength with distilled water in equal measure, and the system had been drained of the OE Super coolant. I haven't had CVT serviced or fluid changed (but it's on my list). I do have larger tires on it (225/65 17). I never got an overheat light, but I'm certain that 247 is too warm.
Personally, I would never use any other coolant other than Subaru OEM Super Coolant. The OEM spec coolant for our Subarus is formulated to preserve aluminum and eat away the engine. Flushing the heater core may also help with any issues. I would flush the system to get rid of the Prestone Coolant and replace with Subaru Blue super coolant. (Just a suggestion). Good luck.
 

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Discussion Starter #12
I would put the CVT SERVICE,,,DRAINFILL at the top of your list and radiator change at the bottom . What the cause of the hot coolant could be... I would be inclined to bet on the CVT since you have serviced the coolant.
Being that Suby has extended the warranty on the CVT to 100000 miles ,and you experienced overheating under mild conditions ,I would file this under "problem" worthy of factory service.

Did a scangauge give you the coolant temp? It can also give the ATF temp, as well..

It could be that your betters is driving it like she stole it-well before it warms up in the morning. Can't hurt to baby it for the first 3-4 miles.
FWIW, I have had 2 drain [email protected] 30 k mile intervals....70 k miles on odo now.
Coolant temp came from the value on the center display. For long trips, I keep that up, and switch between that and two of the efficiency readouts to try to 'beat my high score' in order to keep my foot out of it.

She babies it until the blue coolant light goes off, but yeah, after that, she drives it like she stole it.

So, you're suggesting that the CVT fluid having broken down over time and use; it isn't cooling efficiently, and that is somehow causing the coolant to heat up?
 

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Personally, I would never use any other coolant other than Subaru OEM Super Coolant. I would flush the system to get rid of the Prestone Coolant and replace with Subaru Blue super coolant.
I would wholeheartedly agree that this should be your starting point. Especially if you had no issues prior to this alteration.
 
2017 2.5i Fozy CVT
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[QUOTE="RubrDuky, post: 7565965,
So, you're suggesting that the CVT fluid having broken down over time and use; it isn't cooling efficiently, and that is somehow causing the coolant to heat up?
[/QUOTE]It's heating up more than fresh fluid would. ,,and this heat is being
transferred to the coolant.
Note that if your glycol /distilled water mix is biased towards the former it will not cool as well as a mix biased towards the later.
 
2017 2.5i Fozy CVT
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I would wholeheartedly agree that this should be your starting point. Especially if you had no issues prior to this alteration.
Maybe the Suby coolant was not fully flushed out w water prior to the Prestone ethylene going in and they reacted in some unknown way
My old Saturn after [email protected] auction was filled with sludgy coolant that looked nothing like poly or ethyl glycol. More like chocolate pudding. The overflow/expansion tank had fresh green ethyl glycol though for looks...Since it was factory filled with orange Dexcool(poly gly), I can only assume that mixing different types is bad news.
 

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Wife's ride is a 2015 Forester 2.5i with the CVT. We use it for road trips, mostly around the southwest. Sometimes offroad, but often in the heat.

Last trip, water temp got up to 247°F while driving for just a few minutes; I didn't even think I was pushing it that hard.

I have an all aluminum radiator in my WRX, and I can't get heat into the car in the winter to save my life, it's so efficient at cooling.

But I can't seem to find anything available that's all aluminum for her car.

Couple of questions then:

Is there anything that's close that might work with a few minor modifications?
Is there a significant difference between the FB25 radiator, and what's in, or is available for the XT?
Is there anything available for the XT that might work?
Uhh.. custom radiator?

I can't fathom that running that hot is good for long-term life of heads, and seals, etc.
Hi RubrDuky,

247f sounds very hot for normal driving conditions. Sounds like something is not quite right.

If recently changed coolant, maybe confirm that all air is burped out of system, and that water pump is operating okay. Excessive heating might indicate an increase in internal friction i.e. something not quite right with oil lubrication. Maybe confirm oil type, quantity and pressure. Other source of excess heat in gas engine, is too lean a mixture e.g. too much boost or insufficient fuel supply (check fuel rail pressures, fuel filter for blockage).

I have 2012 Forester (140k kms / 85k miles), coolant still factory original (still tests at 50% with neutral pH). Has factory plastic tank radiator, and sits at 191-195 Deg F (88-91 Deg C), all year round. Can’t even get the fan to come on in Drive Thru on a hot day.

My temp gauge on dash has never moved from its normal operating temp position (it’s whole life), and monitoring ODBII data, it also shows consistent temps. Also put a Mishimoto temp gauge radiator cap (MMRC-GS) on the other day (just for interests sake), and it reads slightly cooler than gauge (which is expected due to distance from sensor).

Although I have never had over heating problems (luckily), I did however put a Mishimoto Radiator fan shroud on. It was for a WRX model, I just chose it based on location of mounting holes and location of overflow bottle. Except for one bolt, they all line up. I could have left the last bolt off, but I just used a 2” piece of aluminium ‘L shaped’ plate to make a bracket. Other than that, just had to configure the fan connectors. After doing this I realised that for my car, the factory radiator is more than sufficient.

Since the shroud change the temp stays much cooler. The fan only comes on for the A/C. And in really cold weather, it does take a little longer for the car to reach its normal operating temp e.g. at the point in the road where it would normally be at 191 Deg f (88 Deg C), it’s still at say 158 Deg f (70 Deg C).

I’d say radiator fan shroud is the best mod to try first. But find out what’s causing the overheating first.
 
2017 2.5i Fozy CVT
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That radiator about doubles the coolant volume. The WRX just doesn't get hot with that radiator.
Dogs brings up a good point about air in the system.Maybe that's the case with your WRX ,only the heater core is full of it or there is a faulty valve that directs coolant to thecore. Or,,worst case, the core is clogged,rusted due to a lack of fresh coolant from time to time.
Since the Tstat controls engine temp may be t hat could be at fault, Hard to say from my viewpoint.
I highly doubt Suby would release thousands of WRX's into service w ith nonfunctional heaters/ defrosters, especially into colder climates.


You have two Suby cooling systems that need attention to be sure.
 
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