• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


Overheating Issues in Daily Driving Conditions

Messages
142
Likes
8
Location
Los Angeles
#1
So here's the situation that i'm at a loss for:

It's currently around 110F in north Los Angeles during the day. yes this is hot.
My car had a mountune stage 1 tune on it with no other performance mods.
My car previously has hit 225-230 in the canyons in and around Los Angeles. That was the highest I had seen it and that was trying to keep up with significantly faster cars.

So that brings me to this week,
I am absolutely babying the car, not going over 2,000 rpm a/c off 55 on the freeway. No matter what I do from the time I start the car all the way until I get to work the temps just continue to rise. Before they would usually stay in the general range of 190-205 and on the way home today coasting around 45-50 on the freeway i was seeing them up to 250 F. Going up any slight incline (my own street) is nigh impossible and requires a concerted effort with a break taken before the hill. I just went outside to start the car and from the moment it turns on temps just rise like 1 degree every 30 seconds. So it's obvious something is not right; this is not just normal hot weather behavior the car is completely underivable. What I have noticed is that the radiator fan does not come on while idling but does come on after I turn on the A/C and after the A/C is turned off it stays on. I have also noticed that the outside temperature indicator has begun fluctuating. If i turn the heater on and coast in neutral the temps do go down slightly but this is (1) in no way feasible since its 115 degrees out and (2) they go right back up almost immediately. Before I take it in this weekend, has anyone had this issue or have any ideas because I've searched the forum and cannot find anything specific. The coolant level is at max and it was serviced about 1500-2000 miles ago.

Forgot to mention, car has now been flashed back to stock and is still exhibiting same issues.
 


Messages
188
Likes
83
Location
Baton Rouge
#2
I have had similar issues in the past, but yours seem to take it to 11. Take a look at the intake/ambient temps and the charge air temps you have, I consider 115-120 charge air temps to be heat-soaked for my car, that is about 20ish deg over ambient in my weather. I believe charge air temps are post intercooler, but it is 5am right now so I don't remember well. We have extremely high humidity here in Louisiana (google says it is 94%) and temps all in the 90s, sometimes low 100s. I don't want to think about 110. When it hits the 90s mid-day in traffic around here I lose about 1-2 psi in peak boost compared to night time driving.

The guy who owned this car before me lived where it would freeze in the winter, so I think he had a 60/40 radiator fluid mix. I went down to the ford dealer and brought back a bottle of the concentrate radiator fluid. Did about a 60-65% distilled water to 35-40% motorcraft orange stuff, then added redline water wetter on top of that. That help my issues out a lot. I also fabricated a mishimoto J-line FMIC (massive...) into the front bumper and went with a mountune stage 2 tune. My only issues now are in slow moving traffic and I drive like a crazy person...petal is like a 20 psi on off switch for the turbo with "MAX AC". Just can't get enough airflow going if I run the AC on full blast. I've have hit the dummy temp light twice before the FMIC, accessport, and tune. After tinkering, it has gotten hot but I haven't maxed out the gauge again.

What is the weight of your oil? I found that running a thicker 5W-30 actually increased my running temperatures as well. I did a little experimenting. I have TRIED to overheat the car when it is 70s-80s out. It just doesn't happen for me. Seems the factory radiator is a little underwhelming...but I only have seen issues midday in the 90s, after the concrete can cook stuff on it. I'm probably going to get a mishimoto radiator in the future. Have seen them for $450 on discount here and there.

The red flag here is that the radiator fan isn't coming on for you. During a hot day with the AC on or off mine sounds like a jet engine all the time. Faulty something, somewhere? When I stopped by my dealer to ask, the first thing they asked then mentioned to me about was the fan then a sticky/faulty thermostat. The tech said they have seen a number of cars with issues on those two parts since the temps have gone up. I feel for you, anything above 40 C can kill people. 45 C? 50 C? Really nasty weather. Hope you get your issues resolved! Let us know what happens.
 


CanadianGuy

4000 Post Club
Messages
4,097
Likes
945
Location
Southern Ontario
#3
If you get this situation again do this. open your windows and turn the heat to max. Yes heat and yes max. This will force the cabin heat exchanger to work like the radiator to cool the engine. This really works in a pinch but you will be sweating buckets.

If this works than you have a few things to check. First do you have enough coolant in the reserve tank. Check when cold add if required. Yes your fan should turn on by itself. Even when parked. After a hard drive the fan will turn on to help cool the engine. As [MENTION=4189]Xaendeau[/MENTION] mentioned you should have your fan checked. I seem to recall there was a TBS for the fiesta (maybe the base model) about the cooling fan. You should also have the coolant thermostat looked at, maybe it is not clicking to open to allow the water to circulate in the cooling stage..
 


Messages
189
Likes
30
Location
El Paso
#4
This happened to me a week ago. Temps here hit 105ish. On freeway, stop in go traffic, coolant temps hit 245* with AC on. Had to shut the AC off, turn heat on, windows down and limp home. Temps hovered around 230-235 the rest of the drive. Fan worked fine, relay good, no coolant leaks, working thermostat. This happened to me once last summer, though not as bad. With this in mind, my plans on getting an X37 had to be delayed in order to get the Mishimoto radiator. The problem IS the radiator. Installed the Mishimoto, filled with 50/50 distilled/Ford Orange and the car rarely passes 200* coolant temps no matter what I throw at it. I drive around 80 miles a day, temps are 100+, and 6 of those miles are up a 8% grade mountain pass. I think the highest I've seen is 206*. I did have to remove my Boomba intake manifold spacer for the radiator to fit :(. I know there was a rumor that some stock radiators had some flashing inside the end tanks that was causing flow restrictions, was this ever actually seen. I need to take my Sawzall to the OEM unit and see if this is true.
 


LilPartyBox

1000 Post Club
Premium Account
Messages
1,492
Likes
774
Location
NYC
#6
Messages
189
Likes
30
Location
El Paso
#7
It wouldn't hurt to use the heavier duty Transit relay used in the recall, but SloCal has a 15MY and I think the TSB is for 16's. However, it would definitely be a cheaper thing to try before the radiator. You can pull the relay off and visually inspect it.

The new relay will not fit in a 2014's fuse box, prongs to big. 2014's use a 40A relay and the new part for 2016's is a 70A. Not sure about 2015's.
 


Pete

Active member
Messages
784
Likes
332
Location
San Diego
#8
I would agree with the radiator. At 50 mph it should not matter if the fan is on or off there is enough airflow going through the system. Our radiators are tiny! I just upgraded to the mishimoto radiator this weekend and at 102 degree weather here in San Diego I went for a hard canyon cruise with the ac on. Only hit 220 max temp. In stop and go traffic these past two days I have seen only 185 as my max temp reading (I also installed the mishimoto thermostat since I was there). To check your fans have your car idling and around the 200-210 mark the fans should kick on. Since they work when you have the ac I would double check with the idle test.
 


OP
SloCal
Messages
142
Likes
8
Location
Los Angeles
Thread Starter #9
Thank you all for the help. [MENTION=1650]Pete[/MENTION] what temps were you seeing before the radiator install?


Sent from my iPhone using Tapatalk
 


Pete

Active member
Messages
784
Likes
332
Location
San Diego
#10
Thank you all for the help. [MENTION=1650]Pete[/MENTION] what temps were you seeing before the radiator install?


Sent from my iPhone using Tapatalk
On my last track day at streets of willow it was 94 degrees and I was hitting 245 and backing the car off (with the heater on full blast). Before in stop and go freeway traffic I would see 195-210 as my temps with no ac on (and before this heat wave hit). Hope that helps for reference.
 


Messages
80
Likes
10
Location
Colorado Springs
#11
Something must be wrong. I went to LA this weekend and on my drive home on the 5, I noticed no sort of problems with the car at all. It was 106 in the Valley, and all the way through the Grapevine and then some before night started happening.
 


stuntdoogie

2000 Post Club
Messages
2,202
Likes
173
Location
NYC
#13
Something must be wrong. I went to LA this weekend and on my drive home on the 5, I noticed no sort of problems with the car at all. It was 106 in the Valley, and all the way through the Grapevine and then some before night started happening.
What year is your car?
 


OP
SloCal
Messages
142
Likes
8
Location
Los Angeles
Thread Starter #15
Update

Something must be wrong. I went to LA this weekend and on my drive home on the 5, I noticed no sort of problems with the car at all. It was 106 in the Valley, and all the way through the Grapevine and then some before night started happening.
So it cooled off a bit and its like low-mid 90's lately. temps will still climb to 220 if i don't actively monitor them. last night i went up to the snake with a 1le and a couple m4's going balls out uphill and they were running 185-195F and meanwhile it took me less than minute to feel the power cut out slightly and i started hitting 230F. Pretty frustrating. It was about 67 degrees out so shouldn't be any problem. Car was noticeably slower than usual as well. Friend with camaro said to change thermostat but i feel like its a little beyond that. He suggested water/water wetter mix like a couple of you guys mentioned but I also read about a plugged up radiator on this forum. Really hard to find time to take it in.
 


Messages
15
Likes
1
Location
Redwood City
#17
Changing the thermostat might not be a bad idea. I don't know what the thermostats are like in these cars, maybe they are fully computerized and cost $800, but if they are the old school kind it should cost about $10 and hopefully take just a few minutes to install. If so, it's worth a shot, a sticking thermostat can definitely cause over-heating. It would be great if it was a simple $10 solution like that. Also possible there's excess air in the cooling system. Google "burping cooling system". Best of luck to you, I know how frustrating chronic issues like this can be.
 


Messages
226
Likes
38
Location
Tarzana/Oxnard
#18
Also when I called dealer they told me that even if they're doing warranty work, they won't give me a rental because I don't have a rental warranty. what kind of f*** bullshit is that? If their product doesn't work right I have to pay to drive another car while they fix their mistake? Never heard of that before.
It's typical that non-premium brands don't include loaner cars as part of warranty coverage. It's up to the dealer's discretion whether to provide a loaner.


Sent from my iPad using Tapatalk
 


Pete

Active member
Messages
784
Likes
332
Location
San Diego
#20
You can say the temp gauge on the car went up. They have a dummy feature and won't move unless past 240 degrees. Also changing the thermostat is a lot of work. You have to remove the bumper, intercooler, crashbar, radiator, remove the serpentine belt, move the alternator, and then you can get to the thermostat. I changed mine a month or two ago with the mishimoto unit and radiator while I was there.
 




Top