Typical transmission temps?

Towing the sxs I see around 203* in the pan and converter at 70mph. Slow down and unlock the converter and it’ll easily go to 220* at the converter.

 

Ahhhhh this might make sense as to why it was eliminated then. They switched to a different more “environmentally friendly” AC refrigerant maybe it’s less efficient and they needed all the space to make it work.

 

Correct, in 2018 they used the new refrigerant in the same radiator with the integrated cooler and it proved to not cool very well so they took out the transmission fluid section to allow for more refrigerant.

 

My '20 had 58k miles on it when i picked it up last year, had no cooler installed. Just for reference that other people can check, my thermal degradation number was at 3699, which i would figure is pretty low.

I changed the fluid: drain and filled, drove it a few hundred miles, then drained and filled it again when i added a cooler. Fluid was dark when i changed it but not too crazy. About as expected after 60k miles.

There are posts that mention when the fluid temp exceeds a certain threshold (not sure what that is), it will lock the torque converter more often and in more gears (to include 2nd and 3rd gears). Not sure if this is factual or if we have evidence of this somewhere. Could explain why we aren't seeing all the expected failures.

 

Did I read early in this thread that 302 degrees in 2019+ is the limit before the light comes on?

 

What's the owner's manual say? Ooops...

 

That is historically the number Toyota uses for a warning. It’s 150 degrees Celsius.

 

Says nothing about temperature. Just checked starting on page 225

 

Thanks.

Was on a 15 minute all highway drive home and backed in the driveway. Put in 4H and began to pull out a 15' Arborvitae tree. Light came on shortly after I started. I shut the truck off for a an hour or so. Think any damage was done or just perfect time to do a spill and fill?

 

These transmissions are extremely tough / overbuilt for a half ton - I doubt damage was done if you shut it off when the light came on and allowed it to cool.

I’d do 3-4 drain and fills to try and get as much of that overheated fluid out as possible - or purchase a cooler and you can do a full swap pumping it out the cooler line 2 quarts at a time.

 

Thanks. I never was one to worry about not having a cooler. I don't tow or haul heavy. I expected to have the trans heat up but didn't think it'd get that hot as i've done this exact thing in times past.

Looks like I have some drain and fills in my future.

 

Just remember to, that 4 low should be used for any low speed 4 wheel driving, 4hi going slow will quickly raise temps.

 

Yeah I’m thinking that was the bigger cause. Strange though because it was only for like 10 min. But I guess that’s enough to make the temps climb

 

You should check your ATF thermal degradation counter, curious what it is now.

 

How do I do that? Is it integrated in the head unit?

 

No unfortunately you need an OBD reader to see it, I use the OBDlink MX+ which will show it but you can only reset it with Techstream.

 

Bought a OBDII reader. Here’s what I’m at now. The trans temp was after a 24 mile round trip with most highway and some town driving. Interestingly, as I’m sitting here in the AC while my wife is in Aldi, the degradation number is now up to 5409