8F35 - 8 Speed Transmission - Temperature/Cooling

[anthonym6]

I own a 2025 with the 2.0 and the tow package. During normal driving I can see transmission temperatures around 200F-210F and when towing I see 220F-227F. Ambient temperature doesn't seem to make a difference. I was told from a Ford transmission engineer that the temperatures I am seeing is normal and they don't start heat mitigation until around 250F.

Another recent thread points to the 2025 only relying on the cooler mounted to the transmission and not the additional cooler mounted to the radiator as seen on earlier model years. Wanted to share some info that I have found from the Ford service manuals.

This vehicle is equipped with an external transmission fluid heat exchanger. The transmission fluid heat exchanger is an oil-to-coolant fluid cooler which is mounted to the lower LH side of the transmission. The cooling system also consists of a coolant control valve mounted to the upper rear of the transmission. The transmission fluid flows from the transmission to the transmission fluid heat exchanger and back to the transmission. When the transmission fluid is below normal operating temperature, the coolant control valve closes, stopping coolant flow to the transmission fluid exchanger. When the transmission fluid is at or above normal operating temperature, the coolant control valve opens, allowing engine coolant to flow to the transmission fluid heat exchanger. The transmission fluid heat exchanger transfers heat from the transmission fluid to the engine coolant.

2022 Service Manual
Thermostat Opening Temperatures

Starts to open	80°C-84°C (176°F-183.2°F)
Fully open	97°C (206.6°F)

2025 Service Manual
Thermostat Opening Temperatures

Starts to open	194 °F (90 °C) to 201 °F (93.8 °C)
Fully open	222.7 °F (106 °C)

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[RR - All the way]

Probably about to show my mechanical ignorance, but how do you see transmission temperature during normal driving????

 

[r0tax]

As a 2025 owner, I also see normal Trans temps of upper 190s to 210 *F

I think these temps are OK. And actually allowing any condensation/moisture boil off/evaporate is actually a good thing.

I haven't towed with mine (only 2k rating anyway), so can't comment on that.

From previous Auto trans (GM) I towed with, 230-240*F was typically 'ok'.
If seeing 240+ for a long duration, I think pulling over to allow it to cool would be best.

 

[r0tax]

Probably about to show my mechanical ignorance, but how do you see transmission temperature during normal driving????

I use Forscan Lite on my phone, via Bluetooth dongle in the OBDII port.

 

[anthonym6]

I use an OBD adapter and an app called Car Scanner (https://www.carscanner.info/) along with my iPhone. It is also available for Android I believe. I can see it using Carplay on screen while driving.

 

[Cancunbadlands]

I use Forscan Lite on my phone, via Bluetooth dongle in the OBDII port.

Can you do coding with this version or you need the laptop windows version????

 

[Cancunbadlands]

I use Forscan Lite on my phone, via Bluetooth dongle in the OBDII port.

Wich one?!

 

[r0tax]

Wich one?!

I run the Independent Edition + License.

Can you do coding with this version or you need the laptop windows version????

No to programming or modifying module parameters.
It can scan for Error codes, run Tests, and Service functions.
Realtime 'dashboard' (where you display a gauge), and 'graphs' (where you display the same data in a time graph; useful for troubleshooting or learning).

Side note: you can "save" a session to file, and view/playback all of your data, useful for viewing graphs on a computer with a high res display.
Sorta what I consider data-logging.

I had a Cobb AP gauge/tuner on my previous vehicle, and I like information about the engine.
It was very handy being able to monitor knock sensors, ignition timing, boost targets and peaks, oil temp, and Fuel quality with specific gauges on the AP.

I really wish I could find oil temp in Forscan, "I" think its important for a turbo'd vehicle. If anyone knows, hmu. Oh, and a 'intake charge temp' would be cool too.

Oh, and to come back on topic'ish. Trans temp is useful, mostly for knowing when its up to temp and ready to Transmit some torque! Or if your towing; especially at the limits, in both weight and grade/elevation.
You can also find diff/RDU and brake temps..

 

[Chops]

I really wish I could find oil temp in Forscan, "I" think its important for a turbo'd vehicle. If anyone knows, hmu. Oh, and a 'intake charge temp' would be cool too.

A forum user informed that the Maverick does not have an oil temp sensor - but uses other sensor(s) as proxies.

Also, one AI told me no MAF just MAP sensor in Maverick. Another AI said both. ??

 

[Cancunbadlands]

I run the Independent Edition + License.


No to programming or modifying module parameters.
It can scan for Error codes, run Tests, and Service functions.
Realtime 'dashboard' (where you display a gauge), and 'graphs' (where you display the same data in a time graph; useful for troubleshooting or learning).

Side note: you can "save" a session to file, and view/playback all of your data, useful for viewing graphs on a computer with a high res display.
Sorta what I consider data-logging.

I had a Cobb AP gauge/tuner on my previous vehicle, and I like information about the engine.
It was very handy being able to monitor knock sensors, ignition timing, boost targets and peaks, oil temp, and Fuel quality with specific gauges on the AP.

I really wish I could find oil temp in Forscan, "I" think its important for a turbo'd vehicle. If anyone knows, hmu. Oh, and a 'intake charge temp' would be cool too.

Oh, and to come back on topic'ish. Trans temp is useful, mostly for knowing when its up to temp and ready to Transmit some torque! Or if your towing; especially at the limits, in both weight and grade/elevation.
You can also find diff/RDU and brake temps..

TY for your knowledge

 

[r0tax]

A forum user informed that the Maverick does not have an oil temp sensor - but uses other sensor(s) as proxies.

Also, one AI told me no MAF just MAP sensor in Maverick. Another AI said both. ??

'MAP High Resolution' is available on the 2025. (May/likely be on the <2025s as well, i just don't know first hand)
I monitor this, along with Barometer so I can calculate boost from MAP.
MAP will effectively show you Vacuum and Boost.

Ex: if Barometer = 10 psi, and MAP = 30 psi, the turbo is generating 20 psi of boost.
Ofc this gets complicated as Baro changes due to elevation.
13 Baro, with 33 MAP = 20 psi of boost.
If you don't see much elevation change, this prob isn't a big deal.

Then on the flip side of that, anything LESS than the current Baro reading = vacuum

It would be ideal if there was a gauge/reading that simply showed MAP minus Baro at all times. So you didn't have to make the calculations in your head.
It much easier to analyze the data after saving a session, and then reviewing it on a computer.

 

[Escapologist]

Humm, don't you need to know the absolute value of pressure of intake air anyway, makes no difference if MAP reads 30 psi at 10,000ft or 30 psi at sealevel, it's still gonna be the same amount of air needing the same amount of fuel, whether the turbo did 20psi of it, or 15psi of it.

 

[lsxmalibu]

The trans mounted cooler is basically a transmission fluid heater.
The transmission is never going to be cooler than the coolant temp....so why wouldn't ford program the engine cooling fan to come on at 185-190 to lower the coolant temp......which would lower the trans temp by at least 5 or 10 degrees....
Once your towing and the trans fluid temp is 210...220.....that little trans mounted exchanger with 200 degree coolant wont do anything

 

[Tbone289]

My 2024 2.0 4K 8F35 operates at normal temperatures of 184-196 degrees. It sometimes takes 20+ minutes of highway driving to reach that range. The highest temperature I've seen while driving on steep mountain passes with lots of transmission braking is 206 degrees. I haven't done any towing yet, so can't comment on that.

This is the first time I've seen actual bypass valve operating temperatures posted here on the forums. Thanks for satisfying my curiosity!

I would certainly be upset to not have the supplemental cooler mentioned in the ordering information for the 4K package had I bought a '25. I would add a Hayden cooler if that were the case.

However, my understanding is that normal ATF temperatures are roughly 175-225 degrees and fluid breakdown doesn't begin until 240 degrees, and you're staying within that range, so I don't think any damage is being done. You may want to consider adding a transmission drain and fill to your regular maintenance schedule. I've decided to do it annually, and see it as cheap insurance at $25 for 5 quarts of Motorcraft ULV.

 

[anthonym6]

I run the Independent Edition + License.


No to programming or modifying module parameters.
It can scan for Error codes, run Tests, and Service functions.
Realtime 'dashboard' (where you display a gauge), and 'graphs' (where you display the same data in a time graph; useful for troubleshooting or learning).

Side note: you can "save" a session to file, and view/playback all of your data, useful for viewing graphs on a computer with a high res display.
Sorta what I consider data-logging.

I had a Cobb AP gauge/tuner on my previous vehicle, and I like information about the engine.
It was very handy being able to monitor knock sensors, ignition timing, boost targets and peaks, oil temp, and Fuel quality with specific gauges on the AP.

I really wish I could find oil temp in Forscan, "I" think its important for a turbo'd vehicle. If anyone knows, hmu. Oh, and a 'intake charge temp' would be cool too.

Oh, and to come back on topic'ish. Trans temp is useful, mostly for knowing when its up to temp and ready to Transmit some torque! Or if your towing; especially at the limits, in both weight and grade/elevation.
You can also find diff/RDU and brake temps..

The Car Scanner app has Cylinder Head Temperature which is the oil temperature from what I have read.

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