Transmission Temp of 245 - Empty Bed / Flat Land

I recently upgraded my head unit to a Kenwood receiver that displays additional gauge info such as transmission fluid temp.......Let's just say i' not happy with what i'm seeing.

I never thought temps would climb over 220 on an empty bed so i never worried about it.
Turns out, it hits 220 within 10 minutes on the hwy and 250 in texas summer heat.

Big thank you to the honorable folks at TFL for conducting a legitimate test to ensure everyone, temps would not get passed a certain point in the worst of conditions......apparently, they should've conducted a harder test with an empty bed in texas heat on flat land.

 

Add a cooler. Check out @snivilous diy <$300.

I’ve pulled tandem 6x12 in heavy traffic and have seen temps reaching that high too. But it ultimately cycles.

Are you locking in 4th?

 

Are you sure that is not reading torque converter temp? It would move around a fair bit quickly if it was. Just curious how it gets the data.

 

Pretty common knowledge at this point, at least on these forums, I'm sure most 19-21 owners have no clue. Get a @Genuine Cooling Systems cooler or build your own. Personally I have the GCS cooler and have been very happy with it, clean install using OEM parts with a custom mount and setrab radiator. My pan temp stays 185 now.

https://genuinecoolingsystems.com/products/15-row-full-kit

 

$300 in parts and get a trans cooler:

https://www.tundras.com/threads/diy-trans-cooler-for-300.146998/

 

I second this, are you sure your getting the reading brought to your screen correctly? When you use something like a scan gauge you have to have the correct formula for it to calculate temps right. Could this radio be similar to that?

 

To everyone asking.....no that is not the torque converter temp, that is the transmission temp and it's 100% accurate.
The info is fed directly from toyota computer via maestro. I also have scan gauge, it reads the same exact numbers.
The temp get this hot every single time i drive an hour plus in texas heat.

 

My '19 is close to the same, cooler is going in this winter along with a few drain and fills. Not cool, literally.

 

I can't get higher than 227 at the transmission with everyday driving. No matter where i drive, how fast i drive, or ambient temp.

 

Steel pipes are $108 only from Japan. They will stay there being intact for the remaining life of truck, unlike rubber hoses.

 

Agreed - don't mickey mouse around with rubber hoses on such a critical item. I too saw 248 after multiple accelerations in normal traffic driving it like grandma - still would get to 248.

I recommend a fan on top of the cooler and the cooler s/b mounted directly to the AC condenser for Maximum cooling. I added a 5pin relay using the Ignition for signal and Towing fuses under hood for main power - also added an override dash switch for winter.

Won't go above 204 under the most severe conditions now and cruising at 75-80 will hold sub 170 on pan and TC temps. I also run it pinned. Luck all and enjoy those rigs running much cooler and allowing for longer trans fluid change intervals - that helps pay for the hardware.

 

ATF thermally broken down is not everything happening to it in the transmission. The frictions still consume slippage additives from ATF. When ATF becomes dull, friction wear accelerates. You still want to drain pink and transparent, yet dull ATF and replace it with fresh one. On top of that, ATF's function is to suspend worn friction particles, which happens normally during life cycle of transmission. Mesh filter and magnets don't catch 100% of them, only ATF replacement brings the particulate content down.

 

There are two different temps that are read, one is converter return temp, the other is pan temp. My '15 on the scan gauge will climb into the 220's empty if the converter is unlocked on the highway, and I see into the 230's towing at highway speed with the converter unlocked. I'd bet both of your temps your reading are converter temp. Try looking at that with the scan gauge to correlate the temperatures. And like many others have said, get a cooler on that thing. Mine with the factory cooler has the pan temp stay between 185-200 unloaded, and in the 200-210's pulling most trailers. I've hauled my other truck from Denver to Moab over I-70 and the highest I've ever seen pan temps are 235 climbing to the tunnel and over Vail pass.

 

I've had above 270 TC and above 230 pan temps in cool weather on my coolerless 2019. It was that bad. It is that bad with those coolerless Tundras.

Coolerless V8 Sequoia seems to fare better for some reason. Perhaps A/C condenser electric fan helps to cool it down, or transmission computer is programmed differently with regard to torque converter lock.

 

My 2019 towing an 8000# trailer through the hills in Arkansas on a hot day would never get over 260 in S4. Pan temps never over 230. Usually settled around 217 or so when not climbing.

 

I've had the exact same experience in my 2021. So much that I was going to go with the Genuine cooling systems, but by the time i did, they upped their price to $1300 from $800 originally. I basically just pieced together the same kit myself for $500. Although I wished i would saw the $300 one at the time when i was doing this last year.

 

idk how you run that hot, man! Id be worried, too, and the cooler install will fix your problem. Im in a '21 base model with no cooler, and scangauge never shows above 210, and thats when towing a boat in the summer.

 

Heavy LT AT tires and skid plates all the way to gas tank take part in high temps.

 

Trans cooler is probably the best money I’ve spent on my tundra. I pieced together my own kit with OE t-stat, hardlines, etc and a Setrab cooler for less than $700 last year. Just recently did a 1700 mile round trip thru the fairly steep and long mountains of southern VA, WV, and KY towing 3500lbs and the trans cooler kept the pan temp in the 195-205 range almost the entire time (there were peaks of 210-211 pan temps when the converter wasn’t locked up going up gradual grades).

Before the cooler, I would see those same temps (and a bit higher) without towing.

 

I must have a unicorn no cooler setup. Even with full skid plates and cat shield, I see 210 max unloaded (195-205 typical range). 230 towing 5-6k lbs boat/camper. If it's around 100' ambient, the trans is about 5 degrees higher either way.

Also my engine coolant stays the lowest I've ever seen for a truck, always between 188-195. My previous Ram and F150 would typically operate at 215-230.

On the ford superduty forums, some owners are panicked as they are also seeing temps north of 240 and they already have external coolers stock. Ford has the ECU programmed not to turn on the fans until trans temps are over 248 degrees. Their only option may be to reprogram the ECU if they want to bring the temps lower.

 

Interesting. Mine is 212 any day, even in winter. Wife's 22 Sequoia (still V8) is pretty much the same. I'm thinking of replacing the t-stat with colder version in Tundra, the engine gets very hot when wheeling in boonies in winter.

 

I see almost the exact same thing on mine. Monitored temps for over a year and in my day to day driving temps hang out between 190-200. Maybe around 205 on hotter days. I unplugged the UltraGauge and only plan to monitor under heavy load going forward