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

 

I could use some feedback from someone who might know more than me. I have a 2011 SR5 with the 5.7L gas engine. It has the “built in” transmission cooler and a gauge on the dashboard - pretty useless (no numbers and just semi circle gauge that goes from C to H). Pretty much if the truck is running, that needle is halfway between the two (see pic). Only goes lower if the truck has been sitting all night and I first start it. Never seems to go higher either.

But, I have an OBD II reader and use OBD Fusion. According to it, my A/T temp in the pan - when on the freeway whether I am towing or not - sits at 207-210. That seems WAY too high, especially one that has the cooler. Had the transmission fluid flushed less than 2 years ago, drive about 8-10k miles/year, tow my travel trailer during the summer when we go on a couple road trips. But for the past two years it has run that hot - could have been for longer but I only started monitoring it via OBD during the last two years. Could my cooler be bunk, or could there be something else going on? Worries me driving when the temps get that high. But if there is a problem, why doesn’t the needle on gauge on the panel seem to go closer to H? Thanks.

 

Needle is engine coolant temp, not trans. Those trans temps do seem high with a cooler though, have you checked for any debris/mud/oil etc. on the fins that would reduce heat transfer?

 

207-210 running empty down the highway is high. Mine with a cooler runs 175-185 depending on speed and ambient temp.

 

The gear symbol around the temp gauge typically means transmission.

 

I stand corrected, you are absolutely right, didn't realize that was a gauge on 2 Gens.

 

You're realizing why many call that a dummy guage. It won't notify you of a problem until its too late. I'd suggest you try pinning your thermostat to see if that helps bring the temps down.

Does your truck have the standalone cooler up front on the passenger side? Or do you see 2 lines entering the top of the AC condenser from the passenger side (this would indicate you have the later integrated cooler that combines the AC condenser with the trans cooler). Either way it would be worth inspecting the cooler you have and seeing if the fins might be gummed up with bugs or other debris that is causing it to cool less efficiently.

 

I wonder if you could pin the thermostat open?