[GearHead_1]

Nice when a plan comes together.

 

[Fyllek]

This and poor condition radiators or air in the system. Any leaks?

Mine is doing it with a Motorcraft T-Stat purchase from the dealer. Both times I had turbo cooling lines and fittings replaced on each of the turbos, I've have this random heating problem with my 2015 3.5. a Replaced the T-Stat after the second turbo and still having issues. Sometimes it puts up to 260, but revving brings it back down. If I keep the RPMs above 2000 (manual automatic selection and 4th or 5th gear) it doesn't do it.

 

[FanaticalKilla]

Mine is doing it with a Motorcraft T-Stat purchase from the dealer. Both times I had turbo cooling lines and fittings replaced on each of the turbos, I've have this random heating problem with my 2015 3.5. a Replaced the T-Stat after the second turbo and still having issues. Sometimes it puts up to 260, but revving brings it back down. If I keep the RPMs above 2000 (manual automatic selection and 4th or 5th gear) it doesn't do it.

That sounds like a water pump or radiator issue to me. I’d pull apart the system and inspect both replace what you find issues with.

 

[Acezerotv]

Ok hopefully this helps someone with this darn 3.5eco boost 230temp issue. I truly think my whole issue ended up being the radiator expansion tank cap. Nobody wants to or should ever unscrew the radiator cap when the engines at temp. I have a 2017 3.5ecoboost with it just touching 230f rarely on big hill pulls. I drive ks to pa fairly often and this started to happen 2 or 3 times on the steeper interstate areas on the 900 mile trip. It was troubleshooting and determined after i wasn't losing fluid to swap the thermostat to a new part store oem replacement (autozone 195f) like any self repair person would do Imo.

Well that didn't work, did the bleeding as good as i could and had the rattle hole at 12oclock. After replacement truck would go right to 230 under and pull and also in coasting. I then researched further and found this post THANK YOU! So i looked up the rev b HL3Z 194f as shown on here and bought it and found the 186f br3z thermostat for the 2.7/5.0 motor replacement as well. I measured all diameters and lengths and the br3z thermostat is the same build as the HL3Z with the new plastic end as i highlighted in the photo. If you go to ford and it has the old brass lower piece dont buy it. The plastic 1 is the new revision. These are all ford parts number i bought at a local dealer.

Before I got into replacing the thermostat the 2nd time i noticed the expansion tank cap screwed in and out very easily. So with the truck off but still hot and i covered with blankets the cap and unscrewed pressing firmly and it barely let any pressure off. So i bought another cap and it tighten in much tighter and warmed the motor and and tried opening after and it started spraying out the pressure port with much more force.

So check ur cap as shown in the photo with ur truck off and cold and see if that oring is flatened out, mine was very flat (7 year old truck makes sense) and i am almost certain now it was my truck just not getting pressured up to 21psi as required and the system was almost at boil point imo why i was just touching 230 every now and again. I went ahead and swapped to the br3z 186f thermostat also just for piece of mind. The only issue is u may see decreased mpg but i can live with that. And you may also want to find someone/somehow to reprogram the fans to kick on at a lower temp to match the thermostat since ur lowering the opening point. The other photo of the cold vs hot thermostats i got from some1 elses link here that shows why u need the motorcraft direct replacement. I bought all these parts at ford. Not much higher cost than the parts stores anyway.

On my 2nd replacement i had to replace while on my trip so i was able to replace without removing any other parts on the truck with just a deep 8mm 1/4 socket and ratchet. I had a couple hose vise grips with me to pinch the hoses to void as much water/coolant coming out. Its a pain but it was doable to loosen all 3 bolts from the passenger side of the engine area and popped the autozone thermo. out and put the new br3z in. After replacement and bleeding and topping off truck never displayed the truck temps so it stayed under 225 the whole 900 miles just fine.

Also do ur own research but i got a dealer years back to flush out the orange antifreeze and use the universal yellow that isnt as corrosive as the orange style. I guess the orange can weaken soldering and if it mixes with air can start corroding metals. Hope this novel helps!

 

[Boatwaco]

Hope this novel helps!

Welcome to the forum and thanks for the morning read. Much appreciated!

 

[Jason79TX]

Hello all! I've been browsing these forums (seems like non-stop) the last couple of days after developing an overheating issue after a day trip to Houston (510 miles round trip). The last time I had an overheating issue (3 months ago), turned out to be an issue with the water pump. So the dealer flushed the system, replaced the water pump, and everything has been solid ever since. I make trips down to the Beaumont area once or twice a month for work and haven't had any issues since.

Made a day trip to Houston on Thursday and everything went find going down there that morning. Driving back that night, about 100 miles into the drive up Interstate 45, I caught the temp gauge bounce well into the far right side (no digital temp on mine). I let out of the gas and made the first exit I seen. As soon as I hit the off ramp, the temps came back to somewhat normal, but still higher than they have been in the last couple of months. Fans were screaming when I stopped at the gas station and the coolant levels were exactly where they have been since the water pump work was completed in January. I should mention that while I was on the Interstate, I was maintaining around 75-80 mph behind several other people eager to leave Houston.

After thinking things over for a moment, I decided to press on and just keep the heater on max, windows down a bit (it was kinda cool Thursday night after the rains) and just take it easy the rest of the way home. As long as I stayed at or under 65 mph, the temp never went beyond the midway point on the dash. It had previously resided under the midway point prior to this day. I did not have by ODBII device on me that night, but after plugging it in and driving under similar conditions yesterday, I see that "midway" on my temp gauge is 227-232. The point where it had set previously shows to be around 190-195.

Everything I've read seems to point towards a thermostat as good place to start, being sure to order the newer OEM version of course. I'm ordering one of those today and hope it's not a pain to replace. If there's an area I need to look into in addition to the thermostat, please point me in the right direction.

2018 F-150 3.5L EcoBoost XLT 4x4 - 122,305 miles

*From what I can tell, the rad and IC louvers are functioning as they should. But I'm more than fine with disabling them if that could help.

 

[FanaticalKilla]

You could unplug both ic/rad louvers to remove them from the mix.

I would recommend a thermostat first then your going to have to check coolant temp drop across the radiator but Id bet a new thermostat would fix you up.