K2XX Trans Cooler Thermostat Thoughts and Opinions

[dieselfan1]

I'm keeping mine flipped.

Even when it's -15°F it runs cool never hits 100°.

My truck is lifted and running 38s .

It shifts fine.

I'm making some more popcorn. Carry on.

[pokismoki]

most componenets in the trans can handle 190-200 F,  the weak link are the rubber seals. they are what controls pressure to the clutches, and maintains pressure in solenoids and signal pressure to the sensor switches.   ask yourself how long did those brand new rubber wiper blades last on your windshield back in the day. i could never get them to live more than a year with the thermal oxidation from sun roasting them in the the summer.. this is the same problem the 6L80 has with it's rubber seals and O-rings

 

they say the torqueconverter is atleast 100F hotter than whats dispalyed on the DIC,  and on the snout of the trans pump is a rubber O-ring that gets cooked to death. it's responsible for controlling pressure in the Lock up in the converter

[rav3]

1 hour ago, dieselfan1 said:

I'm keeping mine flipped.

Even when it's -15°F it runs cool never hits 100°.

My truck is lifted and running 38s .

It shifts fine.

I'm making some more popcorn. Carry on.

I'm with you bro! AFM deleted too. Mine shifts fine as well, even smoother when cold. I guess GM thought it was wrong too since the revised the TBV with all transmission services! Go figure...doesn't take a rocket scientist to figure this one out.

[rav3]

29 minutes ago, pokismoki said:

most componenets in the trans can handle 190-200 F,  the weak link are the rubber seals. they are what controls pressure to the clutches, and maintains pressure in solenoids and signal pressure to the sensor switches.   ask yourself how long did those brand new rubber wiper blades last on your windshield back in the day. i could never get them to live more than a year with the thermal oxidation from sun roasting them in the the summer.. this is the same problem the 6L80 has with it's rubber seals and O-rings

 

they say the torqueconverter is atleast 100F hotter than whats dispalyed on the DIC,  and on the snout of the trans pump is a rubber O-ring that gets cooked to death. it's responsible for controlling pressure in the Lock up in the converter

To each their own decisions. Go ahead & run yours as hot as you want. That is fine with me. We all do what we do cause we want to. Enjoy your truck....

[Black02Silverado]

@newdude, great post and a ton of information.  Thanks for posting this.  Everyone that has a 2014 and up with the 6l80 and 6l90 would greatly benefit to changing out their thermostat.  As newdude stated GM even realized the issue.

 

I feel that one would benefit from changing out the thermostat and switching over  to a quality synthetic ATF like AMSOIL.  My good fortune with all my transmissions has been the fact that I switched all my vehicles over to AMSOIL ATF pretty much right away.  My 2002 Silverado I had the dealer do a full exchange at 5k miles on the truck.  I did a pan drop and fluid change at 75k miles.  That post is here.  I then switched over to AMSOIL's ATL fluid when they came out with it back in 2006.  I pulled the cooler line and did a fluid exchange.  This was around 100k miles on the truck.

 

I switched over the 2016 Suburban at 10k miles and just did the 2019 Silverado with the 10sp at 25k.  Why so late on it?  Well I was hoping someone would come out with a Youtube on how to do it yourself.  Well it never happened due to the fact that, to my knowledge, the fill plug is on top of the transmission and you really can't get to it.  The dealer fills it back through the cooler lines and then  checks the fluid from the side level port at a certain operating temperature.  I've had the AMSOIL ATL in it now for over 1,000 miles and it shifts great.  To me it has a crisper shift if that makes sense.

 

Then time got away from me and before I knew it I hit 200k and I did a pan drop and fluid change.  I sent a sample off and the results came back good.  In that 100k mile time frame I started towing on occasion, a 10'x20' box trailer for Ainsley's Angels and the weight of the trailer is just under 4,500lbs.

 

Again, installing the  lower temp thermostat and a quality synthetic fluid will keep the transmission running smooth for a long time.

 

One thing I forgot to mention is I change out the transmission fluid every 50k miles in all my vehicles. My 2014 Cruze diesel's transmission runs at 220°F to 225°F according the the Scan Gauge II I have hooked up to it.  Way to hot but it is what it is.

[steelerdude15]

Thank you for the write up @newdude. I flipped my pill when I changed my fluid and filter at 30,000 miles. I’m 100 miles shy of 38,000.  So far everything is fine. When I change my fluid and filter at 60,000 miles, I’ll consider the new thermostat at that time. Then we’ll know for sure how the new thermostat has held up since it’s release.

Edited January 26, 2022 by steelerdude15

[YYC-SIERRA]

Slightly off-topic, but what kind of transmission temps are guys experiencing when driving in 4x4 LO for extended periods of time? 

 

I flipped my pill 1 month ago, everything has been great so far. Averaging 60C / 140F on the highway. The other day I was driving up a steep and rough mountain road (Popocatepetl Volcano - south of Mexico City) and since I rarely use 4x4, I tried it out for a while. After 15 minutes, the trans was about 98C / 208F so I switched back to 2WD, it decreased slightly. 

 

Is this pretty normal for 4x4 LO to run the transmission so hot? The only other time I've ever approached 100 C was pulling a 7000 lb trailer over the Eisenhower Pass in Colorado. 

 

 

[Grumpy Bear]

2 hours ago, YYC-SIERRA said:

Slightly off-topic, but what kind of transmission temps are guys experiencing when driving in 4x4 LO for extended periods of time? 

 

I flipped my pill 1 month ago, everything has been great so far. Averaging 60C / 140F on the highway. The other day I was driving up a steep and rough mountain road (Popocatepetl Volcano - south of Mexico City) and since I rarely use 4x4, I tried it out for a while. After 15 minutes, the trans was about 98C / 208F so I switched back to 2WD, it decreased slightly. 

 

Is this pretty normal for 4x4 LO to run the transmission so hot? The only other time I've ever approached 100 C was pulling a 7000 lb trailer over the Eisenhower Pass in Colorado. 

 

 

 

 

How fast were you driving? What was the ambient temperature? 

 

[customboss]

14 hours ago, YYC-SIERRA said:

Slightly off-topic, but what kind of transmission temps are guys experiencing when driving in 4x4 LO for extended periods of time? 

 

I flipped my pill 1 month ago, everything has been great so far. Averaging 60C / 140F on the highway. The other day I was driving up a steep and rough mountain road (Popocatepetl Volcano - south of Mexico City) and since I rarely use 4x4, I tried it out for a while. After 15 minutes, the trans was about 98C / 208F so I switched back to 2WD, it decreased slightly. 

 

Is this pretty normal for 4x4 LO to run the transmission so hot? The only other time I've ever approached 100 C was pulling a 7000 lb trailer over the Eisenhower Pass in Colorado. 

 

 

If you are from Calgary do you run Amsoil or synthetics in the drivetrain?  4LO on my 2022 LTD 2.7L T Trail Boss Custom is a tractor gear, going 30 mph is too fast.  At least in the snow here.  You get around Bro!  

[lawnboy-5247]

Also slightly off topic but My transmission cooler lines are starting to leak in the flexible hose portion and I know that the lines include the thermostat but I am unsure which part number GM is using with the hose set. Does anyone know if the new part number thermostat is being included with the transmission cooler line sets?

Edited January 29, 2022 by lawnboy-5247

[pokismoki]

17 hours ago, YYC-SIERRA said:

Slightly off-topic, but what kind of transmission temps are guys experiencing when driving in 4x4 LO for extended periods of time? 

 

I flipped my pill 1 month ago, everything has been great so far. Averaging 60C / 140F on the highway. The other day I was driving up a steep and rough mountain road (Popocatepetl Volcano - south of Mexico City) and since I rarely use 4x4, I tried it out for a while. After 15 minutes, the trans was about 98C / 208F so I switched back to 2WD, it decreased slightly. 

 

Is this pretty normal for 4x4 LO to run the transmission so hot? The only other time I've ever approached 100 C was pulling a 7000 lb trailer over the Eisenhower Pass in Colorado. 

 

 

how does it run in 4wd Hi vs 4Lo?

 

you could be on an incline and  may not be moving the truck fast enough to engage tcc lock up, so the torque converter is over working the fluid and creating lots of heat, or vis versa, you need to data log the trans with tuning software to know whats happening inside 

 

try using Manual gear M4 instead of D drive

 

[YYC-SIERRA]

21 hours ago, Grumpy Bear said:

 

How fast were you driving? What was the ambient temperature? 

 

 

SORRY mental block......i meant 4HI, i was in 4HI crawling up this rough AF road for probably 20 minutes, never getting out of 1st gear. Temps were probably 45-55F outside, but it was also above 10,000 feet. 

 

I've used 4LO I think once in my truck's life, on a steep boat ramp pulling a boat out for 10 seconds, that's it. 

 

Awesome graph, thanks for that info. Seems to explain it well, seems like nothing to worry about, given the conditions.

 

I use Amsoil in both diffs, with GM Dex 6 in the transfer case and transmission. 

 

[NE18]

I went up Mt. Washington in D and saw temps 200-210. For some reason, after watching TFL truck and listening to Mr. Truck say higher RPMs cools the transmission better, i went up a smaller mountain, locking out the higher gears (I think I limited the gears to 1st and 2nd) and the temp went up to 230. Maybe you being in 1st the whole time was the culprit?

[16LT4]

On 1/29/2022 at 11:05 PM, YYC-SIERRA said:

 

but it was also above 10,000 feet. 

 

 

There's your answer right there.  Your truck has only the ATF-air cooler (not liquid-liquid heat exchanger in the radiator), so is using predominantly vehicle speed to move air across the cooler (with some fan action, but the fan is pulling most of the air through the engine coolant's radiator).  With reduced air flow (presumably going slower when in 4WD due to the terrain requiring 4WD), increased resistance (heat) in the transmission (turning the extra axle), coupled with air that is less than 65% as dense as at sea level, it's no surprise you saw increased heat.  The dry air at that altitude also has less ability to absorb and retain heat than humid air, too.

Edited January 31, 2022 by 16LT4

[pokismoki]

yes  you need to reprogram the fan settings and install a kateck 175 t-stat for that kinda work out these trucks weight about 5500lbs , you should be in 4LO for inclines to utilize torque, and disable TCC function for  gears 1,2, and 3

9 hours ago, NE18 said:

I went up Mt. Washington in D and saw temps 200-210. For some reason, after watching TFL truck and listening to Mr. Truck say higher RPMs cools the transmission better, i went up a smaller mountain, locking out the higher gears (I think I limited the gears to 1st and 2nd) and the temp went up to 230. Maybe you being in 1st the whole time was the culprit?

Edited January 30, 2022 by pokismoki