I did not replace the thermostat with a MotorCraft. No one had any in stock.
I’m not sure how the coolant would discriminate against a none OEM thermostat. However, I’ve ordered a MotorCraft and it is on the way.

What is wrong with the Orange/Yellow coolant?

The upper and Lower Louvers… are you talking about the Louvers for the Turbo’s Intercooler? If so, I’ve watched them close and open when I remote start the truck.

 

Yes, the up and lower. Depending on the temp they should either be open or closed. The louvers will do a self-check (which usually takes a minute or two), but if they keep cycling open and close after the self-check is complete you might have an issue. When I had the problem with my lower louvers, I could watch the truck's temp cycle with about a 20-degree differential.

 

The orange coolant clumps up in the presence of air? It could also have clogged the radiator but this may be less likely. If you never find the solution it may be worth looking at, I recall a member here who broke off the end caps and the tubes were clogged.

There is a TSB for the change from orange to yellow.
https://static.nhtsa.gov/odi/tsbs/20...71861-0001.pdf
https://www.f150forum.com/f118/3-3l-...2122-a-447028/

 

The orange coolant appears to protect metal by creating a thin barrier layer, where as the gold has sacrificial chemicals for protection.
My guess is that the original thermostat is fine till it hits air for a second time and a thicker layer of protective orange goo builds up on the thermostat. The clearances are too tight and the thermostat won't function correctly.

 

can you recommend a coolant? i have a 2018 5.0 but could flush it this weekend.

 

Somewhere around 2019 all the 3.5 eco's changed to Motorcraft Gold coolant. Mine now looks Arnold Palmer like because the dealer didn't chemical flush the system like I asked. Regardless my issues are resolved.
IM not familiar with the 5.0, but I'm sure you can quickly find out if Gold is the way to go.

 

Very similar issue on mine immediately after cam phaser replacement last month. Got it back and was seeing temps up to 230 AFTER acceleration, where I never saw temps that high before the phaser replacement, even when towing through the mountains in July.

I picked up a Motorcraft thermostat and gasket on Rock Auto (which interestingly enough is a 190* vs. the 195* from the factory - even crossed this with my dealer's parts site to confirm), and a gallon of Motorcraft yellow concentrate on Amazon (makes 2 gallons once you mix it). Swapped the thermostat myself in just a few minutes as I knew i'd have zero chance getting Ford to cover it.

It took longer to drain, refill, and bleed the system than it did to actually swap the thermostat. Now my temps are around 200 cruising, and in the 190's idling. MPG's have come up a bit too.

 

Ford Motorcraft yellow. Part number VC-13-G for the concentrate version.

Not sure how the 5.0 is, but on the 3.5 it is recommended to have a vacuum fill tool. Very difficult to bleed the air out otherwise. I almost tried without it, but ended up buying the tool and wow did that save me a lot of time draining and filling.

 

The vacuum tool helps, but if you don't, you can do it this way:

1. Fill the system and bottle
2. Leave the cap off, make sure the climate control system is OFF, start the engine and rev to 3500RPM. Hold it here for 30 seconds, then bring down to idle and shut off.
3. Leave the engine off for at least 1 minute and check the fluid level in the bottle (it should be a lot lower). You'll most likely hear the air gurgling too. I waited until I stopped hearing it before proceeding to the next step. Top off the bottle again and proceed to step 4.
4. Restart the engine and leave at normal idle until the engine has come up to complete normal operating temperature. This is confirmed by the cooling fan coming on at least once after it has warmed all the way up. Check the coolant bottle again and top off if necessary to the max fill line.
5. Rev to 3500RPM again for 30 seconds. Return to normal idle for 30 seconds, then shut off the engine for 1 minute. Check the coolant bottle again and top off if necessary to the max fill line.
6. Repeat step #5 a minimum of 5 times.
7. Top off coolant bottle again to the max fill line and re-install the cap.
8. Check level for the next day or two each morning after it has sat overnight in case any additional air trapped has purged.

It's important to keep an eye on the coolant level in the bottle throughout the whole process (you can never check it too much). You don't want it to empty completely and wind up sucking in more of the same air you're trying to get out. It also really helps to have the truck as much nose up as you can so the bottle becomes the high point in the system and the air will want to naturally travel there. A set of basic car ramps work great.

 

Yes, it is possible to try to work around it, but that is a lot of steps, time, and heat cycles/run time for the engine. And the heater core is still tough to get all of the air out.

The vacuum tool is a fill and done procedure. Thanks for the detail for those who don't want to use one though.