Stock radiator is just awful.

[Liono]

Bader Field, or did you cross the river and go to Warminster (or somewhere else altogether)?

Bader field, first event of the year.


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[DAW]

I’m thinking of picking up a Mountune as well. I did some autocrossing a couple of weeks ago and the car kept creeping up to 225 between runs. I had to turn on the heat to bring it down. And it hovered around 220 on the whole highway drive back home.

Did you replace the thermostat as well?


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I did not replace the thermostat, no need.

 

[DoomsdayMelody]

I drove like a madman in vegas at 110deg-115deg in 2018 and stuck on the 15 for a while at 112 at idle for at least an hour or so. Never got close to overheating with stock rad. Weird...? The only thing I do at coolant change is add 6oz if Royal Purple Ice.

Now... Let me clear something up.... The stock radiator is still junk in comparison to a mountune, or in general for that matter...lol

I also haven’t had a single issue with temps, I mean they creep up to around 212 F at the stop light just after my favorite driving road, but generally speaking I rarely see it crest 200 F and actually have seen temps drop when I turn the AC on.


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[DAW]

How about when it’s 110 outside?

 

[gtx3076]

How about when it’s 110 outside?

Car was reading 115* when I got in yesterday sitting in full sun and dropped to about 107 or so while I as driving.
190* cruising here, it'll sometimes dip to the upper 180's doing 65+ on the highway. Full stock as far as I know, I've inspected underneath the car and haven't seen evidence of mods (I bought it used).
Maybe the t-stat has been replaced, but if that's the case, that means the radiator is adequate still.

 

[DoomsdayMelody]

How about when it’s 110 outside?

I generally try not to drive very hard when it gets that hot out, because I’m aware of the reputation of the cooling system. That said, it rarely gets above 100 F around me, but there are strategies you can use with the stock radiator that will help keep temps down:

Throttle management: horsepower, or the work your engine performs, is a function of engine load. If there is not something preventing the engine from hitting the RPM commanded by the throttle it will only generate as much horsepower as necessary to maintain the commanded rpm. This is why it’s nearly impossible to hit a significant amount of boost with the car in neutral, the engine can hit the commanded rpm without using the turbo. So try to do the bulk of your acceleration gently or, terrain permitting, on downhill sections. This will limit the amount of heat your engine generates.

use a lower gear than you normally would, this keeps rpms up. More RPMs mean more coolant circulation, and more coolant moving through your radiator overall increasing the cooling efficiency even in a somewhat flawed system like the FiST’s.

Engine braking and coasting. Again this has to do with engine rpm and coolant circulation. You can also mitigate your time you spend completely stopped if you coast just right coming up to a stop light.

These are all relatively simple “driver mod” strategies that cost nothing to implement but can have a surprisingly strong effect on your coolant temps especially if you are having issues.


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[Fiestig]

How about when it’s 110 outside?

Yeppers, as mentioned, that was the minimum temp driving around...

I drove like a madman in vegas at 110deg-115deg in 2018 and stuck on the 15 for a while at 112 at idle for at least an hour or so. Never got close to overheating with stock rad. Weird...? The only thing I do at coolant change is add 6oz if Royal Purple Ice.

 

[TyphoonFiST]

Yeppers, as mentioned, that was the minimum temp driving around...

I Run an additive also...some Nano- coolant stuff ...got it on clearence . And my temps are also similar*

 

[DAW]

Dang!! Have super radiators haha.

 

[Dpro]

I generally try not to drive very hard when it gets that hot out, because I’m aware of the reputation of the cooling system. That said, it rarely gets above 100 F around me, but there are strategies you can use with the stock radiator that will help keep temps down:

Throttle management: horsepower, or the work your engine performs, is a function of engine load. If there is not something preventing the engine from hitting the RPM commanded by the throttle it will only generate as much horsepower as necessary to maintain the commanded rpm. This is why it’s nearly impossible to hit a significant amount of boost with the car in neutral, the engine can hit the commanded rpm without using the turbo. So try to do the bulk of your acceleration gently or, terrain permitting, on downhill sections. This will limit the amount of heat your engine generates.

use a lower gear than you normally would, this keeps rpms up. More RPMs mean more coolant circulation, and more coolant moving through your radiator overall increasing the cooling efficiency even in a somewhat flawed system like the FiST’s.

Engine braking and coasting. Again this has to do with engine rpm and coolant circulation. You can also mitigate your time you spend completely stopped if you coast just right coming up to a stop light.

These are all relatively simple “driver mod” strategies that cost nothing to implement but can have a surprisingly strong effect on your coolant temps especially if you are having issues.


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I do think living in the bay area you can squeak by, Try living in SoCal though and its really a different story. I was seeing high temps but not overheating till I did a afternoon drive on Lil Tujunga and forgot to turn off my air. Car went into panic mode at the top of the crest. I turned the air off and it came back down. Mind you I mellowed out my driving on the way down. I followed suit shortly thereafter with installing the Mountune rad. It gets hot enough here you need air con unless you were born in the desert and/or are a personal sadist to yourself. lol
Ya I grew up in Palo Alto drove Datsun 510’s and 240Z’s all summer long for years with no air. Bought a Hardbody Truck nearly new with no air. Moved to SoCal and it became readily apparent air con was my friend. Sure if you build a purpose built track car or car you don’t drive every day you might get away without air. Though if you drive the car regularly here in the Summer you need air . If you need air you need a better radiator.
At least down here. IMO

 

[M-Sport fan]

use a lower gear than you normally would, this keeps rpms up. More RPMs mean more coolant circulation, and more coolant moving through your radiator overall increasing the cooling efficiency even in a somewhat flawed system like the FiST’s.

Besides the temps dropping due to the high speed fans kicking on when the AC is turned on (in stop and go, and idling conditions), I also notice the above as well when steady state cruising on either the highway, or a 50 MPH secondary road.
The temps will drop from ~190*F in sixth, to the low 180s, or even high 170s in 5th or 4th, even in 90*F+ ambient temps, and still on the factory radiator.

That being said, yes, I am still leaning towards the Pro Alloy radiator from Ron, at least partly because it is not always out of stock (albeit a bit more coin than the Mountune/CSR).

 

[jeffreylyon]

Besides the temps dropping due to the high speed fans kicking on when the AC is turned on, I also notice the above as well when steady state cruising on either the highway, or a 50 MPH secondary road.
The temps will drop from ~190*F in sixth, to the low 180s, or even high 170s in 5th or 4th, even in 90*F+ ambient temps, and still on the factory radiator.

Maybe because the water pump is running faster in the lower gears?

 

[M-Sport fan]

Maybe because the water pump is running faster in the lower gears?

That's exactly what Doomsday was implying, and I was agreeing with as well.

 

[Dpro]

That's exactly what Doomsday was implying, and I was agreeing with as well.

As long as you do not live in a semi arid area that works.

 

[DoomsdayMelody]

As long as you do not live in a semi arid area that works.

I mean humidity has less to do with it vs ambient temps. The Bay Area is not a what I’d call humid, Chicago in the middle of summer can be horribly humid place. Compared to the 2 other areas of the country that I’ve lived in San Jose, while not hot, is still definitely what I’d call arid by comparison.


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[Fiestig]

Anyone who is serious about keeping their FiST will purchase a Mountune radiator. Essential mod.

I have been serious about keeping my FiST since I bought it. 40K later and run normal temps through all of my delightful over-spirited daily driving.....sooooo.... I am not too sure I that is completely true in my instance. For me, If it ain't broke, don't fix it. Just lucky I guess..

If I had an overheating problem than I would have one already. It would have been considered broke... and I would have fixed it...lol.

 

[FiestaST27]

I have a 15’ FiST. I’ve been thinking about upgrading my radiator also, but I’ve never had any overheating issues at all. I live in SoCal, but drove to Laughlin just a couple of weeks ago with my A/C on (to, during and back) and never went over 190 degrees on my coolant temps (going by my AP). When I bought my car, from the local Ford dealership, it was a leased car beforehand (42k miles) and they provided documents to support it and all the maintenance. I now have almost 68k miles and I’ve never had any problems (knock on wood).

But, I did read this post because I’m still considering upgrading my radiator, since I have all bolt-ons installed, tuned with Stratified and keeping this car FOREVER 😁

 

[Dpro]

I mean humidity has less to do with it vs ambient temps. The Bay Area is not a what I’d call humid, Chicago in the middle of summer can be horribly humid place. Compared to the 2 other areas of the country that I’ve lived in San Jose, while not hot, is still definitely what I’d call arid by comparison.


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I think you missed the point and the joke semi arid is not humid . semi arid is pretty much desert which is dry heat which can be brutal.,

LA technically is a desert we average 14 inches of rain on a good year that is considered semi arid. everything around us outside of right on the coast is desert. The San Fernando Valley aka where Burbank is , is literally 10 minutes up the road from me it sees triple digit weather pretty often in the summer.

San Jose is part of the bay area the supposed average rainfall is 17 inches but the bay area is 33 inches year. That is not semi arid and the bay area is a mediterranean climate and yes does not have extreme humidity but humidity was not what I was talking about anyways. lol

 

[Dpro]

I have been serious about keeping my FiST since I bought it. 40K later and run normal temps through all of my delightful over-spirited daily driving.....sooooo.... I am not too sure I that is completely true in my instance. For me, If it ain't broke, don't fix it. Just lucky I guess..

If I had an overheating problem than I would have one already. It would have been considered broke... and I would have fixed it...lol.

Well you are on the Monterey Peninsula no? So I am guessing your not looking at super hot weather . In fact I would bet a hot day for you would be 85-90 max but I would guess your average days even in Summer do not get much above 75-80. That was the way it was in Palo Alto in the bay growing up. San Jo would get up around 90. Ya I just called San Jose San Jo lol.

 

[DAW]

Well maybe my factory radiator was just garbage, because out here in Phoenix it’s been 110 everyday a while. As I said before my oem rad normal driving was 215-225, and at idle forget it. After the mountune instal I see high 180s low 190s same weather, and no overheating, so it DID help and alleviate any stress of( man if I go here will I make it).