2019 Tundra High ATF Temperature

[Whalstib]

Howdy,

Just bought a 2019 Tundra 5.7L 6 speed automatic with tow package, to tow an Airstream. Previously same Airstream with a Tacoma had ATF in the range of 150° to 190° (190° towing up 6% grade in 80° ambient with head wind).

Tundra is running 215° without towing... Fwy driving 65-75mph. Lost of "complaints" about this but consensus is Tundras run hotter for a variety of reasons BUT reading here and elsewhere the ATF itself will suffer with 220° being a caution zone.

It seems part of the issue is a lack of a true ATF cooler and uses a heat exchanger and Toyota more concerned with running cold than hot...

Fine Toyota designed a Tundra transmission that excels at 220°+ BUT can modern ATF actually handle prolonged temperatures without premature failure?

Guys on the Tundra forum are all over the map with ideas but nothing confirmed.

So... CAN ATF handle these extremes day and day out?

Thanks,

Whalstib

 

[Chris142]

I would put a cooler on it.

 

[SZR48207]

Originally Posted by Chris142
I would put a cooler on it.


If it weren't a 2019 I'd agree but it sounds like OP is in a conundrum about voiding parts of the powertrain warranty by adding an external cooler. (yes Magnusson Moss would protect, but you can bet that Toyota would point their finger at the aftermarket cooler in the event of an issue)

OP - There was a recent thread here where another member mentioned the problem - the newer Tundras don't come with an option for a factory external cooler. I would suspect that the horrible MPG the Tundra gets is a reason why Toyota was trying to bump up ATF temps to squeeze out a few points of efficiency, at the cost of higher trans temps which are probably not good for longevity.


There are a few charts that illustrate the risks of higher temps:

So I can think of a few things you might try:

1. Can you modify the front bumper/grille to permit more air flow? Similarly, I know that the Tacoma guys who live near the desert will actually shim their hoods so that they are a half inch higher towards the "back" (along with removing any rubber weather sealing under the hood) to create a gap for hot air to escape.

2. If ground clearance permits, you could possibly attach some external cooling fins to the transmission fluid pan. This will increase surface area so that air flow underneath the vehicle extracts heat.

 

[BMWTurboDzl]

Originally Posted by Reddy45
Originally Posted by Chris142
I would put a cooler on it.


If it weren't a 2019 I'd agree but it sounds like OP is in a conundrum about voiding parts of the powertrain warranty by adding an external cooler. (yes Magnusson Moss would protect, but you can bet that Toyota would point their finger at the aftermarket cooler in the event of an issue)

OP - There was a recent thread here where another member mentioned the problem - the newer Tundras don't come with an option for a factory external cooler. I would suspect that the horrible MPG the Tundra gets is a reason why Toyota was trying to bump up ATF temps to squeeze out a few points of efficiency, at the cost of higher trans temps which are probably not good for longevity.


There are a few charts that illustrate the risks of higher temps:

So I can think of a few things you might try:

1. Can you modify the front bumper/grille to permit more air flow? Similarly, I know that the Tacoma guys who live near the desert will actually shim their hoods so that they are a half inch higher towards the "back" (along with removing any rubber weather sealing under the hood) to create a gap for hot air to escape.

2. If ground clearance permits, you could possibly attach some external cooling fins to the transmission fluid pan. This will increase surface area so that air flow underneath the vehicle extracts heat.



What's the date of this info? If it's old it may no longer apply.

 

[SZR48207]

Originally Posted by BMWTurboDzl
Originally Posted by Reddy45
Originally Posted by Chris142
I would put a cooler on it.


If it weren't a 2019 I'd agree but it sounds like OP is in a conundrum about voiding parts of the powertrain warranty by adding an external cooler. (yes Magnusson Moss would protect, but you can bet that Toyota would point their finger at the aftermarket cooler in the event of an issue)

OP - There was a recent thread here where another member mentioned the problem - the newer Tundras don't come with an option for a factory external cooler. I would suspect that the horrible MPG the Tundra gets is a reason why Toyota was trying to bump up ATF temps to squeeze out a few points of efficiency, at the cost of higher trans temps which are probably not good for longevity.


There are a few charts that illustrate the risks of higher temps:

So I can think of a few things you might try:

1. Can you modify the front bumper/grille to permit more air flow? Similarly, I know that the Tacoma guys who live near the desert will actually shim their hoods so that they are a half inch higher towards the "back" (along with removing any rubber weather sealing under the hood) to create a gap for hot air to escape.

2. If ground clearance permits, you could possibly attach some external cooling fins to the transmission fluid pan. This will increase surface area so that air flow underneath the vehicle extracts heat.



What's the date of this info? If it's old it may no longer apply.


No idea but these charts have been around for a while. That being said, the charts do align with the temperature when Toyotas will illuminate the ATF TEMP warning light on the dash, which is around 300 to 320*F. (basically once that light goes off, the ATF is cooked and you need to service it ASAP).

 

[MNgopher]

What temp does Toyota say this transmission is supposed to run> How about the fluid?

People had trouble wrapping their heads around the 6R80 in the F150's. The thermostat to the cooler doesn't even open until the fluid temp hits 190. They run all day long between 190 and 210. The 4R75 it replaced was typically around 150ish. Made a lot of people wonder what was wrong when that was where the 6R80 was designed to run.

With that chart, F150 transmissions should all fail before 60,000 miles. Regular service schedule is to exchange the fluid at 150,000... Without the fluid being used and the application, those generic charts are not all that helpful...

 

[CT8]

Yes what temps are the transmissions supposed to operate at? Syn oil is still marketed using 1970's GP 1 base oil comparisons.

 

[CT8]

Yes what temps are the transmissions supposed to operate at? Syn oil is still marketed using 1970's GP 1 base oil comparisons.
Originally Posted by MNgopher
What temp does Toyota say this transmission is supposed to run> How about the fluid?

People had trouble wrapping their heads around the 6R80 in the F150's. The thermostat to the cooler doesn't even open until the fluid temp hits 190. They run all day long between 190 and 210. The 4R75 it replaced was typically around 150ish. Made a lot of people wonder what was wrong when that was where the 6R80 was designed to run.

With that chart, F150 transmissions should all fail before 60,000 miles. Regular service schedule is to exchange the fluid at 150,000... Without the fluid being used and the application, those generic charts are not all that helpful...

My F150 has 28,000 miles before failure according to that chart.I change my fluids more often.

 

[Whalstib]

Originally Posted by MNgopher
What temp does Toyota say this transmission is supposed to run> How about the fluid?

People had trouble wrapping their heads around the 6R80 in the F150's. The thermostat to the cooler doesn't even open until the fluid temp hits 190. They run all day long between 190 and 210. The 4R75 it replaced was typically around 150ish. Made a lot of people wonder what was wrong when that was where the 6R80 was designed to run.

With that chart, F150 transmissions should all fail before 60,000 miles. Regular service schedule is to exchange the fluid at 150,000... Without the fluid being used and the application, those generic charts are not all that helpful...


I have not been able to determine the operating temperatures of the transmission!

No shop manual that explains things either

Further investigation reveals...

Following the lines from the small tuna fish can sized and shape "atf cooler" to routes to a 4 x4 x 1.5" square "oil cooler" which is to cool engine oil!

I should mention I and my friends working this out with me are using Scangauge or Ultra gauge OBD readers. I believe both rely upon user entered PID's and to not recognize ATF temps an their own. Also after a trip this afternoon where ATF temp read 215°F via Scangauge I was able to touch the pan and leave my finger in contact for a few seconds...It just didn't feel like 215°.....

Just bugging me...

Thanks.,

W

 

[double vanos]

Well let's see.. Mercon LV has a flash point of 421F. Mercon ULV has a FP of 370F. A trans temp of 220F is a walk in the park for these two oils. At 250F I don't know what all would suffer in the vehicle but I doubt it'd be the trans fluid. Modern transmissions (and the fluid that goes in them)are built from the ground up for temps that, back in 1969, would have equated to a totally roasted transmission. But today, modern design with advanced materials and a dogged quest for efficiency have given us the auto transmissions we currently have. I have no empirical data to back up my feelings, but I suspect the newest trans offerings will give longer service than the slushboxes of yore.

 

[SZR48207]

I would at least be curious what the friction plates are rated for in terms of tolerated operating temps in modern transmissions. The steel and aluminum components can handle 300 no problem but if the frictions start degrading then you'll have shifting issues.

 

[tundraman]

I also have a 2019 Tundra. After the sale I found that Toyota no longer equips the Tundra with an oil cooler. They use the term integrated engine/transmission oil cooling. It appears the warmer is also the cooler. No oil takeoff is present as in previous years so adding a cooler will entail buying the part (p/n Thermostat Unit - Toyota (32970-34030), installation, and cooler/lines. My dealer would not say if it would void warranty. Let us know what you decide.
Regards,
bc

 

[Revving2Redline]

I would try to sneak a qt of Redline or Amsoil ATF in there.Granted a drain and fill for a qt or two isnt much,but a better product looks to be what I would do. Coming from the guy that swappdd Honda HCF2 for Castrol Transmax/Redline Cvt.

 

[Revving2Redline]

Hopefully GReddy,HKS or TRD will make a cooler. If the tranny is next to the engine it couldnt hurt running the best performance oil so that the tranny doesn't work harder than it has to.

 

[zeng]

Quote
Also after a trip this afternoon where ATF temp read 215°F via Scangauge I was able to touch the pan and leave my finger in contact for a few seconds...It just didn't feel like 215°.....

Just bugging me...

OP, you may need to cross-check/calibrate the Scangauge or erroneous readings.

 

[Whalstib]

Originally Posted by tundraman
I also have a 2019 Tundra. After the sale I found that Toyota no longer equips the Tundra with an oil cooler. They use the term integrated engine/transmission oil cooling. It appears the warmer is also the cooler. No oil takeoff is present as in previous years so adding a cooler will entail buying the part (p/n Thermostat Unit - Toyota (32970-34030), installation, and cooler/lines. My dealer would not say if it would void warranty. Let us know what you decide.
Regards,
bc


Mine has this part!

I'm pretty sure it's behind the "oil cooler" on side of trans. It's not as big as it looks in the diagram.. maybe 1/2" thick.. Really stuffed up there. You gotta crawl up and look hard and you'll see it.

I think previous years had it on the other side of the trans but if you look at the schematics (I saw somewhere...) there is a common mounting bolt that goes through both..

Whalstib

 

[MNgopher]

Originally Posted by Whalstib



I should mention I and my friends working this out with me are using Scangauge or Ultra gauge OBD readers. I believe both rely upon user entered PID's and to not recognize ATF temps an their own. Also after a trip this afternoon where ATF temp read 215°F via Scangauge I was able to touch the pan and leave my finger in contact for a few seconds...It just didn't feel like 215°.....

Just bugging me...

Thanks.,

W



Looking through a few Tundra threads seems to show there are two temp sensors on these transmissions - one at the Torque Converter outlet and a pan sensor. They do appear to read differently as one would expect. May want to check the OBD reader codes you are using.

Also appears that 200 degree temps were normalish in some of the threads on 2018 Tundras, so what you are reporting does not seem like it is too far from what others have seen.

I could be wrong though - Tundra's are not in my normal realm of doing repairs!

 

[tundraman]

How do you calibrate a ScanGuage?

 

[meep]

Before changing anything, hook it up and tow, and pay attention to the trans temps. I bet you they go up a hair but stay pretty solid in a range. That being so, it may not need anything at all. Remember, the AT is thermostatically fluid-cooled. If you really want to pay attention, pay attention to the diff when towing, as it is not actively cooled.

F150 doesn't run a loop through the radiator either. There's now a heat exchanger at the trans which cooling is piped back to run through. Keeps the trans warm in the winter and pulls out heat when towing. I think the heat exchanger idea could be better than these cooling loops which crack in so many radiators after ~8 years....

-m

 

[StevieC]

If it has the Thermostat under the radiator like my Highlander did you can just press the end of it to open the thermostat and put a pin to keep it in that position all the time so that the auxiliary cooler is always in use.

IMO The Toyota WS fluid leaves a lot to be desired especially in hotter running transmissions. I'd opt for a better synthetic that meets the specification. Just me though.