There are some F150 owners here who might have experienced some overheat or surge temperature issues. These issues have now been completely solved by Ford with a change in thermostat. BTW, this issue also applies to the Ford Expedition/Lincoln Navigator which have similar 3.5 liter Ecoboost engines. There are some tricks that F150 owners used in the past to resolve the issue such as switching to a 170 degree thermostat or disconnecting the active grille shutters. You will not need to do that anymore with this fix. Reconnect the shutters and dont bother with aftermarket thermostats. This is a complete fix.

The name of the new Ford thermostat is the RT-1252. It has a black end and no gasket on the back as you can see in the photos attached. I put the stock thermostat on the left side and the new RT-1252 on the right side. The main problem causing the overheating issue was the the thermostat was sticking closed but the newly redesigned thermostat no longer sticks closed.

So if you have a 2017-2020 Ford F150/Raptor, 2018-2021 Ford Expedition or 2018-2021 Lincoln Navigator and are finding your truck running too hot then this will be the fix. My truck ran at around 210-220 degrees with the stock thermostat and would surge way past 220 degrees during high demand times. After my truck runs from 200-210 degrees and I cant get it above 212 degrees no matter how hard I tried.

I just joined this site by the way to share this information. I dont participate in websites. This issue has been ******* me since 2018 and I wanted to spread the word on the exact fix for those that need it. Also other things which help keep temperature in line are using the Motorcraft air filter( forget about aftermarket), changing the spark plugs before 50000 miles with the stock Motorcraft plugs...check for most current plug suggested by Ford, and removing the engine cover...serves no other purpose but to dress up engine. However, the main issue is the thermostat.

After the thermostat is changed you can go back to the stock cooling setup to include connected grille shutters. You wont need to do any more cooling tricks after this fix.

 

UPDATE: The F150 has different engine configurations and so there are different thermostats. I got on the Ford parts website right now and all of the most current thermostats have the black end to them (versus the older thermostat with the copper end) I looked real quick and there is a RT-1251, RT-1255, etc. So be sure to check exactly the model that you need, but it appears to me that all of the various thermostats for the F150 have been redesigned.

 

Welcome to FTE Overheatissue,

Excellent first post! I read that you don’t participate on websites, but glad you did here. Stick around for awhile, we have a good group of guys here.

 

Welcome, and thanks for sharing what you learned.

 

I am a Ford Fleet Holder with a Ford fleet number or FFN assigned to me so be confident I know these issues well. Failure to get this corrected can lead to transmission failure, engine damage and turbo damage...premature failures. So if you have these problems go get that thermostat replaced now. The dealer will probably charge you a lot...Im guessing $400 but we do all our own work over here.

We have had 10R80s fail at 70000 miles, turbos at 100k and major engine trouble like the flashing check engine light meaning pull over and shutdown now. Vehicles are not designed to operate at 220 degrees and surge to 240 degrees.

This thermostat completely changed the cooling system of the truck and now I feel like its completely reliable. It took them 5 model years but now we at that point where these issues will be no more. GM is not a substitute as they go through 1st and 2nd model year growing pains with current models.

I was on the highway stop and go traffic and it held at 200 degrees...never happened like that in the past. By the way thr override on the grille shutters is the AC turned on...opens it right up.

 

I appreciate this notice but have a question to see if my issue could be related to this. On a recent trip through Colorado, coming down the mountain from Pueblo going South, my AC suddenly turned warm. After a few second it returned to cold. I failed to look at the heat gauge at this point but several hours later while going through West Texas I was running at the speed limit of 75 mph. It was about 105 degrees outside, and I felt the warm air again. The temp gauge was sweeping up, then down, back and forth for a few minutes. What was interesting (and confusing to me) the temp went up when I was going downhill and down when I was going uphill. The opposite of what I would expect. It never went into the red, but I slowed down and it moved back to the normal level with a few bumps up and down again for about 30 miles. From that point on, the gauge was steady on the normal operating temp for the next 150 miles until the trip ended. Once home, I checked the fluid level and it was fine, no leaks anywhere and nothing looked any different. I've been driving it for the last 400 miles and the gauge has not varied at all and the AC is as cold as ever.
I have a 2018 Ford F-150 with the 3.5L Eco boost engine. 73,000 miles. It was very hot when this happened, and we were fighting winds of 30-40 mph head on and from the side. Any ideas if the thermostat change might fix this?

 

UPDATE: I had the thermostat changed to the correct one. Took it out and the same problem was there. Took the truck back to service and they said they would look at it and change it again if warranted. I went to pick it up and the mechanic told me he had blown out the radiator and a ton of what looked like cottonwood tree "cotton" came out. I told him we do not have any cottonwoods around our area but agreed to try it an come back if it is still varying. Told my Wife and she reminded me of driving through Rapid City, SD and running through a wall of the floating cotton from the trees. It was so heavy I thought it was smoke. Here's to great mechanics and Service Advisors.

 

Hopefully that will have it solved for you.
I can't imagine any way for anything to get in the cooling system since it is a closed system.

My overheat issue was solved by a new radiator, thermostat, thermostat housing, water pump, and overflow tank cap.
My truck was in an accident and since all that was done it has been running perfectly.

 

Bad wording on my part. The debris was in the radiator coils and between the radiator and the trans cooler.

 

Oh, now that does make sense.
Obviously, I thought you meant it was inside the cooling system.

 

The OP's original thermostat was redesigned by Ford and the opening temp lowered to 190*, both changes fixed the issue. On a related note, installing a lower temp thermostat will help protect the engine from momentary high loads, but the engine can still get heat soaked at constant high loads, like from towing. The solution to that would be a larger radiator, intercooler, and transmission cooler depending on the engine, transmission, and the type of cooling problem you are trying to solve. One more thought on this- for EcoBoost F-150s, I have seen light bars installed in front of intercooler grills- very bad idea. That may look nice, but it completely blocks airflow to the intercooler. Too hot of an air charge will significantly reduce power.

 

Hi guys
super solution! I replaced mine after temp increase during towing and driving on the highway with low rpm. Replaced it a few months ago and never saw the temp digits anymore. Rock solid!

 

Ive been fighting coolings fans running on high even with temps in the teens for tthe last 30k miles. currently at 125K. Ford said all f150 3.5 eco's run that way. Well it didnt when new.. E-fans would come on high at 65mph and 10 seconds after stopping they would drop back to normal, or be fine at 25mph road then go up a slight incline and would come on full. Outside air temp didnt seem to change anything form freezing to 90 degree outside temps.

Never had my engine temp gauge move when this happened and seen my tranny temp run from 206 to 225 when towing.

Recently started to see engine temp spike on dash gauge when towing uphill with 4k load.

did some research and found this post. Just replaced this in about an hour and issue fixed. e-Fans do not run on high anymore just in city traffic, etc. No temp spikes towing anymore etc.. Old thermostat obviously was set for a higher temp opening and finally starting failing to show the spikes..

Thank you for the post.

now if only my local ford dealer would research this..

They told me I had a faulty biased AC sensor in my heater for for a quote of 4k to replace. Bet it wouldn't have fixed the problem unless they also installed the new thermostat and not said anything.

 

I just had the thermostat replaced and cooling system flush. Still overheating. Replaced rad, replaced louver actuator and new antifreeze again. Still overheating. The truck has 207000km on it. Never overheated till the phasers were replaced. Do I need a water pump? I'm not sure they can figure this out. This is my 4th truck, bought from new and the second that had phasers replaced. None of the other trucks ever overheated. Any Ideas?

 

@Overheatissue - Thank you for this detailed post! Turns out I was on a family vacation and we took our 2019 Expedition. During the road trip I noticed the temperature gauge periodically showing actual temps, highest I saw was 238 degrees. It would always appear momentarily and then go back down and the actual temperature reading would then disappear (only showing the gauge at that point, not the ### degrees reading). This concerned me as it wasn't normal and because we had an 800 mile road trip back to Texas. Thanks to your post I was able to go to a nearby Ford dealer to get the replacement part, and then find a mechanic who could swap the thermostat for me. Drive home had no temperature spikes! Very grateful for posts like these and you taking the time to help others out

PS: sorta crap that Ford took the time to send a cam phaser voluntary recall notice but neglected to mention that this part spec had changed and was causing issues?