Stock radiator is just awful.

[gtx3076]

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).

Could've been air in the old system.

At this point it doesn't matter, but I wouldn't tell new owners that the radiator is a must have unless they'll be driving under extreme conditions like racing.

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[The Cuzi]

That's news to me. I know the stock radiator will come out without taking the crash bar off. I did the Mishimoto radiator on my '15, which I know is huge. Maybe only really needed for that one.

Yeah. The Mountune is super easy/simple with no bumper or crash bar pull. Solo my install for Mountune was somewhere about two hours start to finish (including bleeding the coolant system).

 

[The Cuzi]

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).

I think everyone's stock radiator is garbage. If someone has a unicorn that doesn't overheat it is one of those don't look a gift horse in the mouth situations. Just looking for heat or radiator on this forum shows how many people have overheating issues with basic and daily driving if they're not in the northern latitudes.

 

[Fiestig]

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.

My regular residence is in Pacific Grove, CA but we also have a family home in Vegas which I am back and forth pretty regular usually minus the covid lockdowns. So I have been through all max temps on a pretty regular basis. The reason I mentioned the temps I did in my 1st post is because it was the hottest over the last few years while I was there and it was blistering hot.

I assure you I am not trying to argue that the stock radiator is good enough. It will not be as good as a mountune by any stretch of the imagination. But at the same time I can't complain with what I have. With a couple other people mentioning the same, I wonder if there was a bad factory run for the radiator. That would be the most likely scenario seeing some of the non modified low mileage that are having issues.

 

[Dpro]

My regular residence is in Pacific Grove, CA but we also have a family home in Vegas which I am back and forth pretty regular usually minus the covid lockdowns. So I have been through all max temps on a pretty regular basis. The reason I mentioned the temps I did in my 1st post is because it was the hottest over the last few years while I was there and it was blistering hot.

I assure you I am not trying to argue that the stock radiator is good enough. It will not be as good as a mountune by any stretch of the imagination. But at the same time I can't complain with what I have. With a couple other people mentioning the same, I wonder if there was a bad factory run for the radiator. That would be the most likely scenario seeing some of the non modified low mileage that are having issues.

Ya that theory would float except people have been having radiator issues in warmer climes across all the years. This is not something that happened during one period in one year.
So it would suggest that on a whole the cooling system is a weak link as it was designed in a Country with colder climates ( Germany). Plus if you look at a stock Fiesta the whole front grill area has better airflow than a FiST because they did not shove a intercooler in the lower section. People tend to forget that having an intercooler in front of a both a air con condensers and radiator severely cuts down on airflow.
The stock radiator is indeed tiny so even taking away the percentage of flow the intercooler does can have an effect in warmer climes.
You cite driving around Vegas and through Vegas but two questions come to mind. 1. Did you push it hard in the heat? Like at the track or running canyons? and 2. Did you drive in stop and go traffic for 45 minutes to an hour or sit in bumper to bumper going nowhere. These are the kinds of things that will make temps with the stock radiator skyrocket.

I am not arguing this just pointing out real world things that make your assumptions above more of a unicorn than born out reality.

Bottom line for our cars is a upgraded radiator is a practical wise modification if you are into performance with our cars. Which is really why most of us bought the damn thing. lol

 

[Fiestig]

You cite driving around Vegas and through Vegas but two questions come to mind. 1. Did you push it hard in the heat? Like at the track or running canyons? and 2. Did you drive in stop and go traffic for 45 minutes to an hour or sit in bumper to bumper going nowhere. These are the kinds of things that will make temps with the stock radiator skyrocket.

Yeppers, as stated originally.

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.

I always rock the FiST like an 80's hair band (The Metallica sort, not the Cinderella sort...lol).

I don't track my #1 FiST. If I did I would have already done a Mountune rad as a precautionary measure.

 

[powermatt]

Yeah. The Mountune is super easy/simple with no bumper or crash bar pull. Solo my install for Mountune was somewhere about two hours start to finish (including bleeding the coolant system).

Good to know. Quite likely I'll do theirs next time. The Mishimoto radiator worked very well, but it was a lot of work to get it in there. No fitment issues like their intake, but the upper mounts were quite tight.

 

[DAW]

Could've been air in the old system.

At this point it doesn't matter, but I wouldn't tell new owners that the radiator is a must have unless they'll be driving under extreme conditions like racing.

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I’m a new owner, got the car new in July last year..

 

[DoomsdayMelody]

I’m a new owner, got the car new in July last year..

Yeah, Ford often... well, sometimes, has questionable engineering decisions/quality control. The true “blue oval” fans refuse to acknowledge it, and love to defend everything about the company but as someone who has only ever personally owned Ford products, I was stunned when i helped my significant other purchase a Mazda 3 and later a Toyota Prius Prime (it drives like a bad of dicks with no handles) of just generally how much less annoying but not deal breaking stuff she had to deal with in the first few years of ownership. Give your car time it’ll surprise you with something that would’ve been easily addressed at the factory/in the design studio , there will be plenty of head scratching whenever it happens.

I remember at my last job, we had a fleet of 6.0 power stroke F350s and there’s a coolant hose that is directly touching the shaft that comes out of the steering column and attaches to the rack. Eventually the shaft would rub through the hose and you’d leak coolant all over the place. Would’ve been super easy for Ford to modify the hose as there was tons of space around the area through which they could’ve routed it, instead the service bulletin update they sent was some hard plastic sheathing which was essentially a 6” long piece of pvc pipe cut in half so you didn’t have to remove the hose and 2 zip ties. Super easy to put on, but also, how did the truck make it out of the factory like that? It’s because Ford corporate makes questionable decisions with surprising reliability.


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[Scotman2]

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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It's very unsettling to have the car overheat in line to make a run. Or, have it go into limp mode on course. I had both situations occur to me. That was a few months after I had replaced the fried cooling fan relay! Which had caused the car to nearly overheat in traffic. After all that I decided to not do any modifications until I had sorted out the issue. The Mountune radiator is what should have been O.E. the stock one is excrement.

 

[alex7]

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 😁

I think if you intend to keep the car like you mentioned, it would be a logical investment. Even if you had not added all those power mods, the car's oem cooling stuff would inevitably fail anyway. I responded because I myself had been debating this for a few years now. It really has been holding back track use. Just recently bought one and its waiting in my office to be installed.

 

[M-Sport fan]

At this point it doesn't matter, but I wouldn't tell new owners that the radiator is a must have unless they'll be driving under extreme conditions like racing.

...or they live in the desert like DAW, or maybe Death Valley.

 

[jmrtsus]

Like others my radiator has been flawless in my uses. I have the MP215 and OCC as only mods. 40K miles, 4 years old and 21 states. Have done S LA and S FL at 95 and up with a/c on full blast. Did the width of ND in 94 degrees and running 90-95 and only 2 bars in the normal zone no mater where I have driven. Daughter just returned with her stock '18 FiST from the Phoenix area and no problems. So no, not everyone thinks the stock radiator is garbage! Everyone drives differently and has different mods on this forum. It is mostly people that drive the car hard tracking or autoX and many have lots of mods that are seeing high temps. Until I have problems I will not replace it. Based on many posts when the FiST forum and car were new I thought the OEM tires would need replacing at 10K miles and brakes not long after. Also was almost panicked into a radiator. As it turned out the tires went 30K and the brakes 32K and never had any cooling issues. Same with axle problems, I stressed out over leaks that never developed. Has my FiST been perfect, no......blend door, Sync 3 and roof weather stripping failed. What the radiator does in another car gives me no grief. I have been on the Forum for a long time and waited until '16 to buy mine to give the bugs time to show up. Glad I did! I think when declaring something as not good it should be referenced to "for my applications". So for mine and my daughters applications (under 215 HP) stock FMIC the stock radiator has worked fine.

 

[M-Sport fan]

Plus if you look at a stock Fiesta the whole front grill area has better airflow than a FiST because they did not shove a intercooler in the lower section. People tend to forget that having an intercooler in front of a both a air con condensers and radiator severely cuts down on airflow.
The stock radiator is indeed tiny so even taking away the percentage of flow the intercooler does can have an effect in warmer climes.

^^^ THIS!
I am always amazed that no one on here ever considers the draw back to using those YUUUGE intercoolers, whether tube and fin, OR bar and plate (BA, DHM, Pro Alloy, Pumaspeed) as far as blocking the radiator (even a great/efficient aftermarket one), especially with edgy tunes in very hot climes is concerned.

Let's also consider that whatever air is actualy getting through those giganormous ICs is heated to ABOVE ambient temps as well, which does not help any (another thing I've never once heard brought up on here as a concern ).

(And yes I know that efficient big/hybrid turbos can actually run cooler than the over-stressed/over-spun factory snail, but still not hundreds of degrees cooler. )

Do the tuners as a matter of course/necessity program the high speed fans to come on MUCH sooner, so as to at least keep everything from blowing up in stop and go traffic in 110*F ambients when running these brick wall air blockers?!?!?

 

[Dpro]

Do the tuners as a matter of course/necessity program the high speed fans to come on MUCH sooner, so as to at least keep everything from blowing up in stop and go traffic in 110*F ambients when running these brick wall air blockers?!?!?

Actually yes some do. I know Dizzy does and I would guess the others do too. It’s a simple thing to program in. If not one could always ask them when they are purchasing the tune. It’s a minor detail for them much like turning off the shift light and raising the rev limit.

 

[DAW]

^^^ THIS!
I am always amazed that no one on here ever considers the draw back to using those YUUUGE intercoolers, whether tube and fin, OR bar and plate (BA, DHM, Pro Alloy, Pumaspeed) as far as blocking the radiator (even a great/efficient aftermarket one), especially with edgy tunes in very hot climes is concerned.

Let's also consider that whatever air is actualy getting through those giganormous ICs is heated to ABOVE ambient temps as well, which does not help any (another thing I've never once heard brought up on here as a concern ).

(And yes I know that efficient big/hybrid turbos can actually run cooler than the over-stressed/over-spun factory snail, but still not hundreds of degrees cooler. )

Do the tuners as a matter of course/necessity program the high speed fans to come on MUCH sooner, so as to at least keep everything from blowing up in stop and go traffic in 110*F ambients when running these brick wall air blockers?!?!?

I dunno man, my MAP IC was a direct fit, don’t think it would make that much of a difference then stock, does it?

 

[DoomsdayMelody]

I dunno man, my MAP IC was a direct fit, don’t think it would make that much of a difference then stock, does it?

Regardless of whether or not it interferes with air flow to the radiator, if your charge temps drop you’re making more power (wee!) than you would have and more power means more heat for your cooling system to deal with.


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[M-Sport fan]

I dunno man, my MAP IC was a direct fit, don’t think it would make that much of a difference then stock, does it?

I was not referring to the 'direct fit', factory style/location ICs, but the huge oversized ones which block MUCH MORE of the height of the radiator, if not ALL of it!

 

[M-Sport fan]

Regardless of whether or not it interferes with air flow to the radiator, if your charge temps drop you making more power wee than you would have and more power means more heat for your cooling system to deal with.


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And again, IF it is dropping those charge temps that much, all of that transferred heat is going directly into the radiator as well, so even MORE heat (on top of the heat from the added power) it has to contend with.

 

[Scotman2]

^^^ THIS!
I am always amazed that no one on here ever considers the draw back to using those YUUUGE intercoolers, whether tube and fin, OR bar and plate (BA, DHM, Pro Alloy, Pumaspeed) as far as blocking the radiator (even a great/efficient aftermarket one), especially with edgy tunes in very hot climes is concerned.

Let's also consider that whatever air is actualy getting through those giganormous ICs is heated to ABOVE ambient temps as well, which does not help any (another thing I've never once heard brought up on here as a concern ).

(And yes I know that efficient big/hybrid turbos can actually run cooler than the over-stressed/over-spun factory snail, but still not hundreds of degrees cooler. )

Do the tuners as a matter of course/necessity program the high speed fans to come on MUCH sooner, so as to at least keep everything from blowing up in stop and go traffic in 110*F ambients when running these brick wall air blockers?!?!?

My FiST was mechanically BONE stock when the issues started. I don't think that normal urban driving without boiling over is expecting too much. The problem is widespread on many stock Fiesta ST's. If you didn't have any problem, yay for you. But some people fried their engines or wrecked the cylinder head.
It stopped me dead in my tracks from putting one more nickle into the car. I have pivoted to building a Lotus 7 type sportscar. I think a 12k totally impractical but track capable car is a better deal than a 21k hot hatch that requires 10+ grand in upgrades just to be marginally more reliable and slightly quicker is not a good value proposition. But the Fist is still a fun ride. I like it.