2014 fiesta coolant temp hitting 115 Celsius

[Noahcec]

I’m not sure if this is the right place to post this but I’ve been having some cooling issues and just trying to see if I can get any potential fixes or insight on the situation
Recently I’ve noticed while going up hill or on hard excel my st will hit temps of 115 and then drop down I have combustion gas tested the coolant tank and found no signs of head gasket failure new to this car so was hoping someone could help me out. THANKS!

 

[LostInTransit]

How long ago was a coolant flush performed?. If one hasn't might be best to do so. Have you or a shop done anything (tampered with) the coolant system? if so this could mean someone invariantly added or mixed incorrect coolants. Plus you may need to install a new thermoset. What you're looking for is to see if there is any sludge in the coolant system. if so this could mean someone mixed coolants which would contaminate the system and blocking the coolant flow.

 

[Intuit]

239F... for the earlier model year ST, some folks have reportedly resolved high-temps by swapping out the radiator. (search forums) There was also a recall IIRC.

 

[Dialcaliper]

I’m not sure if this is the right place to post this but I’ve been having some cooling issues and just trying to see if I can get any potential fixes or insight on the situation
Recently I’ve noticed while going up hill or on hard excel my st will hit temps of 115 and then drop down I have combustion gas tested the coolant tank and found no signs of head gasket failure new to this car so was hoping someone could help me out. THANKS!

Are you running the A/C when this happens? It sounds like what I was experiencing previously - the A/C compressor cycles on and off, and every time it comes on while going uphill or romping on it in any kind of mildly warm weather, the temperature would spike up.

The radiator on the ST is just plain inadequate. It’s the same as the base model Fiesta with no significant improvements for a hot running turbo engine. Old coolant and any kind of blockage to the radiator will make the problem worse, as will an upgraded intercooler or running a tune - the stock tune’s 20 sec “over boost” behavior is there specifically to limit the occurrence of overheating.

Triple pass Mountune totally fixed the problem (installed a 180F/82C thermostat at the same time). Temperature barely budges now from operating, even when I get on it.

 

[Capri to ST]

As stated above, I would see if your car is subject to the recall.
Cooling problems seem to be hit or miss, some have them, some don't. A lot of people on here have cars that are tuned and significantly modified, which obviously puts a greater load on the cooling system.
The stock radiator does seem to be different from the base Fiesta. According to Tasca parts the radiator part number for the Fiesta ST is
C1BZ-8005-A
and the radiator part number for the non ST Fiesta is
AE8Z-8005-B
They also show an MSRP about $120 higher for the ST radiator, which might indicate a more robust part.

 

[Intuit]

Cold start on my 2016 with A/C, it ran the fan on a lower speed for like a few seconds then went to higher speed.

 

[M-Sport fan]

Cold start on my 2016 with A/C, it ran the fan on a lower speed for like a few seconds then went to higher speed.

Are there separate relays for the low speed and high speed fans??

I am wondering why my car seems to be the only one out there which will run cooler (with the factory radiator) when the AC is on, than when it is off (in stop and go/crawling traffic and sitting at stop lights).

When/once moving above 25 MPH, with the AC off, the temps will drop to the low 180s to a max of 188, even in the 98*F ambients around here lately, so this is perplexing.

Could the low speed fan just not be switching on at all, and the temps drop with the AC on because that instantly switches on the high speed fan?

 

[Intuit]

Some vehicles (if not many) operate the fan in sort of a fail-safe mode where it runs until the ECU shuts it off. Sometimes they always run following an engine start then shutoff. Might be the case here dunno; but instead of being shut off the ECU engaged it on a higher speed. Per diagram it's a single relay. There's a module attached to the fan. The module receives info from the ECU/PCM and the module in turn controls fan speed.