Transmission overheating with less effort than expected.

[Snakebitten]

The 10r80 does indeed have a internal thermostat. I believe it is up above the valve body, so not easy to get to in order to replace.
It's entirely possible to have a faulty thermostat, but you rarely ever hear anyone mentioning it being replaced.

And it's the reason you would need one of those expensive machines that can heat up the transmission fluid in order to flush and replace all of the fluid. If you can't get the fluid hot and keep it hot, you can't keep the thermostat open. If it's not open, you can't access all the fluid.

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[HammaMan]

The 10r80 does indeed have a internal thermostat. I believe it is up above the valve body, so not easy to get to in order to replace.
It's entirely possible to have a faulty thermostat, but you rarely ever hear anyone mentioning it being replaced.

And it's the reason you would need one of those expensive machines that can heat up the transmission fluid in order to flush and replace all of the fluid. If you can't get the fluid hot and keep it hot, you can't keep the thermostat open. If it's not open, you can't access all the fluid.

Have you seen anything mentioning its internal thermostat? Given that the engine will feed heat to the trans for heating it up, not sure what the internal thermostat would do. On raptors and SSVs they have an external thermostat that either routes the fluid to a coolant/oil heat exchanger for heating, or when the oil is hot it bypasses sending the oil to the air/oil cooler mounted in front of the rad.

Given the e-motor, not sure if the PB does any warming from the engine or not -- haven't seen anything explaining precisely how the loop works.

 

[Snakebitten]

I'll see if I can find more specifics on the internal thermostat, but it wasn't mentioned in the basic overview.

 

[Snakebitten]

I believe that I am wrong about the "internal thermostat" on the 10r80 MHT transmission. And Ford actually called the device a thermal bypass valve, rather than a thermostat, although it basically operates the same way.
Anyways, it appears that Ford removed the internal bypass valve (around 2015, and it was the 6r80) and relocated it externally, where it bypasses the heat exchanger until the transmission fluid is warmed up.

The Powerboost does indeed have this external (to the transmission case) thermal bypass valve. As well as an external control valve on the engine coolant hose for blocking (bypassing) flow to the transmission cooler/warmer.

The engine coolant side:

The transmission fluid side:

 

[FordConvert]

Have them check the fluid level. Overfilling causes the fluid to froth and not cool effectively. Happened to me and a few other folks on this forum. Sorry if this has already been mentioned.

 

[Kurt V]

Tow/Haul does lock out 10.

 

[Atlee]

Tow/Haul does lock out 10.

Not on my MY22 XLT Power Boost. I physically lock it out.

 

[Kurt V]

Not on my MY22 XLT Power Boost. I physically lock it out.

Hmm. It does on my 2023 Lariat PB.

 

[Atlee]

Hmm. It does on my 2023 Lariat PB.

I'll double check mine tomorrow to make sure I haven't made another observation mistake.

 

[Nighsight]

Does anyone know, or can someone find out what parameters are required for the coolant control valve to open and flow coolant through the cooler? I'm toying with the idea of inserting a cooler between the valve and the trans cooler inlet. That would make it easier to control the transmission temperature independent of the engine temperature.

 

[HammaMan]

Does anyone know, or can someone find out what parameters are required for the coolant control valve to open and flow coolant through the cooler? I'm toying with the idea of inserting a cooler between the valve and the trans cooler inlet. That would make it easier to control the transmission temperature independent of the engine temperature.

You can buy 3 days access to the service manual for $26 and see what it's got for you in there.

 

[redduke916]

I have a 2021 PB with tow package and just went through a nightmare with my truck and transmission overheating! I posted on this forum and got a lot of good feedback from members. Bottom line is though every Ford technician and dealership I went to all said the same thing that I shouldn't have to lock out gears or even run the truck in tow-haul mode with my 8,000 lb trailer at normal highway trailering speeds.

After months of dealership visits across the US and Canada and a new transmission with no resolution they finally changed the complete transmission cooler and so far no more problems but it only happens after several hours of trailer towing which I am currently not doing so only time will tell.

I bought a ODBlink MX+ and keep my eye on all my temps now on the Phone app.

Good luck and keep us updated.

I have the same vehicle with Max Tow package. been towing an 8,000 pound trailer with no issues. 15,000 trailering miles. at 45,000 truck miles the techs completed the transmission check on hard upshift. completed tsb 24-2176 overhauled transmission and flushed cooler.

Now at the end of an 8,000 mile trip with trailer, truck mileage at 53,000, I got an overheat alarm and it showed 273 degrees. backing off cooled down immediately. the dealer tech says I need an new transmission cooler as it "is clogged". Offered me a larger aftermarket cooler until I told him it should have the larger one with max tow package. very hard to believe its clogged. Read through this excellent thread but still suspicious.

Where is the temperature sensor? could that fail?
2nd issue, could be the valve - how to determine that it only opens "1/4 of the way"
any thoughts?

 

[v8440]

My advice to anyone experiencing such high trans fluid temps is to have the fluid changed asap. Temps that high are supposedly very hard on the fluid, causing fast degradation. I'd want that out of my transmission in a hurry.

 

[Korça]

I'm having the same transmission overheating issues.
'22 Lariat PB with max tow package - rated around 13k# capacity.
Towing 5,600# camper with hardly anything in it and dry.
Never had any issues towing (I tow it a lot) until in Sept '24 when the dealer decided my trans needed to be overhauled even though I had never had any issues with hard shifting or overheating.
I had brought it in for a clicking noise in the rear end - they finally admitted the clicking was not the transmission but the rear axle (which is under recall with no fix determined yet).
I have to pull over frequently to let the tranny cool down. Ambient temps have been below 60F. Pulling in Texas and Oklahoma on I-35 which is rolling hills, not steep at all.
Once temps get into the 90's this spring it will be worse.
It's at the dealer again. 4th time since September. They are throwing up their hands and don't know what to do.
I've run tests and it doesn't matter if I have the A/C on or off, or if I'm using the generator or not.

EDIT: I'll be leaving updates on my overheating saga here: https://www.f150gen14.com/forum/thr...way-twice-high-voltage-battery-warning.32148/

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