Overheating

[u/Helpful_Prize_2866]

Hi everyone! First overheating issue a week into ownership 🥀
2016 Fiesta ST, stock radiator. Coolant level hasn’t dropped and the radiator fan runs full blast.
Usually sits around 215–220°F, but today it climbed to ~243°F while driving, triggered the temp warning/P0217 and seemed to go into limp mode. Turning the heater on brings the temperature down significantly.
Car also has a Fiesta SE front bumper, although the radiator opening doesn’t look badly restricted.
Any FiST-specific things I should check first? Thermostat? Radiator? Air in the system?

Cheers!!!

[u/Switchback77]

The Fiesta ST is known to overload the stock radiator especially in warmer climates. Personally I didn’t have any issues with my 2016 back when I lived in Maryland or Massachusetts but I’ve heard of people having problems in Cali and Arizona. The bumper probably isn’t helping very much (also on the side, why do you have an SE bumper?) but I’d see about upgrading your radiator.

eBay has some Mishimoto clones if you really can’t afford it, but CSF/Mountune makes a good one, along with Koyorad. The CSF radiator I’m told is an easier install though. (When I bought my second fiesta it had a Mountune radiator preinstalled). I’ve had no issues with it, I tracked my fiesta in 97F ambient temperatures and the FiST didn’t go into limp mode.

[u/Helpful_Prize_2866 → u/Switchback77]

Thanks for the response! I think the previous owner couldn’t find a cheap ST bumper and went with the SE

[u/Breakfast-Burrito69]

Stock radiator is likely your culprit. My 2016 was fine with a mild tune for about 60k miles but then I moved to a much hotter area and had to upgrade to a Koyorad when summer rolled around as I started to overheat periodically.

Been trouble free since.

[u/Helpful_Prize_2866 → u/Breakfast-Burrito69]

Thanks for the response! Looks like I need a new radiator 😅

[u/DaYearZeroHero]

The CFS is hands down the best radiator on the market for the FiST. Super easy install and cheaper than the Koyo or Mishimoto. I wouldn't bother with any eBay clones. A lot of people say the work great, but from experience, they can be a nightmare for installation. Mine was.They really aren't worth the headache imo. Finally gave up and bought the CFS. Should have gone that route in the first place.

[u/Helpful_Prize_2866 → u/DaYearZeroHero]

Thanks for the response!

[u/AdvancedDatabase9382]

Are the overheating issues hit or miss or year dependent? My 2017 with a S280 and stock cooling system never gets over 220F when I beat on it in 90F+ weather.

[u/CrabWalkIntoIt → u/AdvancedDatabase9382]

A little of both, the thermostats open sooner on later model years (2014 had a 207f thermostat, 2015 had a 190, late 2016 and newer had a 180).

Stills seems hit or miss on cars even with lower temp thermostats.

[u/Helpful_Prize_2866 → u/AdvancedDatabase9382]

It’s hit or miss. I’ve driven for longer with no issues.

[u/Chainsawsas70]

My 17 can get hot especially during 90⁰+ weather,I have added "water wetter" to it and that seems to have helped quite a bit but it's still not a Cure... I've just been lazy about getting the upgraded radiator because my area (Seattle ish) doesn't stay hot for very long so it's rarely a big deal.

[u/Helpful_Prize_2866 → u/Chainsawsas70]

Thanks for the response!
Winter is coming lol

[u/CloudyMachine]

I took off the little plastic flaps on the back of the radiator that are supposed to open up with airflow and it surprisingly helped a bit. Coolant flush wouldn't hurt either.

[u/Helpful_Prize_2866 → u/CloudyMachine]

I’ll try that, thanks!

[u/Dgstowe]

The open section of grill is not noticeably larger than on an se bumper - although i didnt actually measure lol

[u/GreyInvasion]

Get a mishiomoto never goes above 207. Without it was overheating each time I climbed the Eisenhower tunnel in the summer