Transmission Thermostat Delete Pros vs. Cons

BlaineBug · February 3, 2022

4 hours ago, 14burrito said:

So you kind of have two options now.

1. Pull flip

2. Check your new t-stat housing, if its stamped with a "70" it has a new lower temp 135 stat installed vs the original 180.

21-NA-199 will provide more details. You might be able to get the dealer to cover the cost of a new tstat assembly if you provide them that TB.

Thermostat part number is 13511136 which shows to have maybe been replaced by 86774933.

Not ALL of the new transmission thermostat housings have the stamp on the outside of the aluminum which complicates things further.

Grumpy Bear · February 3, 2022

1 hour ago, mikeyk101 said:

Taken from information in the bulletin:

"The new TBV can be identified by the “70” stamped into the bottom of the valve"

Unless a new trans thermostat was installed within the last month or so by dealer, it won't be part #86774933 and won't be stamped with the 70. I imagine the reason for stamping the new housing with the identifiable 70 is for the tech to be able to identify it for reasons of trans fluid service. With the old thermostat, the trans temperature would have to be increased to 180⁰ or so to do the exchange. With this new redesigned thermostat, the transmission temperature would only have to be raised to 135⁰ or so.

1 minute ago, BlaineBug said:

Not ALL of the new transmission thermostat housings have the stamp on the outside of the aluminum which complicates things further.

Mine was not stamped 70. At least at first look it wasn't. What looks like happened un magnification, is that was stamped 70 the some other lines of numbers stamped OVER the 70. Just FYI.

BlaineBug · February 3, 2022

4 hours ago, 14burrito said:

13511136 was for my 6L80, 2019 Tahoe L83 motor. 86774933 shows to be the successor, did your t-stat housing have a "70" stamped on it by chance?

If you read the TB, they state that the part number did not change and it requires the tech (or end user) to verify there is a "70" stamped in the housing. Whether that has changed or not, I do not know, as the verbiage does not show to have changed within the TB.

Hence why I stated, if one was to order the old tstat housing- they would need to ensure its stamped with a 70. If it is, it has the 135. If it doesn't, it has the 180 and can be used for a pill flip option.

The part I received had the new part number on it. The techline bulletin also states that there is a new part number. I believe this information about the part number not changing is false to be honest.

mikeyk101 · February 3, 2022

Interesting. Here is the one I bought end of last year.

mikeyk101 · February 3, 2022

4 hours ago, Grumpy Bear said:

Mine was not stamped 70. At least at first look it wasn't. What looks like happened un magnification, is that was stamped 70 the some other lines of numbers stamped OVER the 70. Just FYI.

I just found this. And it has a note that states:

" The "70" may be difficult to read as a dot print may be stamped over the "70". "

14burrito · February 3, 2022

9 hours ago, mikeyk101 said:

Interesting. Here is the one I bought end of last year.

As I personally expected

Grumpy Bear · February 3, 2022

2 hours ago, 14burrito said:

As I personally expected

Yep, on mine those little numbers were stamped right over the 70 obscuring it.

Eddie 70 · February 12, 2022

Just thought I would add to the thread. My truck is still running and shifting like it should. The temps are still lower than they were with the thermostat in place. I drove it 11 hours to south Florida last October with no issues at all. I don't remember the exact temps the trans was running but it was no where near the opening point of the stock thermostat. Maybe 150-160 degrees F. at the max. I'm still happy with the flip and I still do my one gallon trans fluid swap every 15k miles.

16LT4 · February 13, 2022

14 hours ago, Eddie 70 said:

Just thought I would add to the thread. My truck is still running and shifting like it should. The temps are still lower than they were with the thermostat in place. I drove it 11 hours to south Florida last October with no issues at all. I don't remember the exact temps the trans was running but it was no where near the opening point of the stock thermostat. Maybe 150-160 degrees F. at the max. I'm still happy with the flip and I still do my one gallon trans fluid swap every 15k miles.

Last july I ran NY to KL, FL straight through and again in the return trip, and also saw far lower temperatures than ever with the stock thermostat. I may have already posted them in this thread, but IIRC they were lower than the revise thermostat temperatures. If I lived South of the Mason-Dixon, I would probably have left it flipped instead of trying out the revised thermostat.

BlaineBug · February 17, 2022

I haven't towed anything and never do but I can confirm that after a 1,200 mile journey from the north to the south with ambient temperatures ranging from 20' degrees to 75' degrees that I haven't noticed the transmission temperature rise above 149' while having the new revised transmission thermostat installed. The only place I haven't taken notice was descending the mountains of Tennessee, where they have runaway ramps in place. Going home we'll be driving the opposite way going up so hopefully I'll remember to keep a watchful eye on the temp for s&g's. With the Original transmission thermostat the transmission temperature would likely be around 190' by comparison.

Ksz426 · May 10, 2022

I read through this thread and learned a lot. But I have a couple of questions. I did the pill flip on my 2017 Suburban 6l80. I did it because I tow a 6500lb travel trailer and the trans temps were a shy over 200 flat towing and climbed to 210-215 when towing up a grade. With the swap, towing on a level plane results in trans temp of 175 and when going up a grade 195.
I’d like to get the temps down a little more so I was considering adding a Tru-Cool 30k trans cooler. Btw, currently the fluid goes through the radiator tank and then the condenser cooler.
However, my Suburban has the shutters in front of the radiator that I understand close at certain times. Would this negate the benefit of the added cooler?
Appreciate any thoughts or experiences.

Thanks.

14burrito · May 11, 2022

3 hours ago, Ksz426 said:

I read through this thread and learned a lot. But I have a couple of questions. I did the pill flip on my 2017 Suburban 6l80. I did it because I tow a 6500lb travel trailer and the trans temps were a shy over 200 flat towing and climbed to 210-215 when towing up a grade. With the swap, towing on a level plane results in trans temp of 175 and when going up a grade 195.
I’d like to get the temps down a little more so I was considering adding a Tru-Cool 30k trans cooler. Btw, currently the fluid goes through the radiator tank and then the condenser cooler.
However, my Suburban has the shutters in front of the radiator that I understand close at certain times. Would this negate the benefit of the added cooler?
Appreciate any thoughts or experiences.

Thanks.

Yes, the grill shutters suck for trying to being down thermal deltas. I have been fighting this issue myself.

If you get a tuner (HP or Diablo) you can simply disconnect and remove the shutters. Once you do this you will receive a fault code in the engine along with a check engine light. With HP or Diablo, ask the tuner to simply make that P code "not reportable" and boom, done. Once I am better, the grill shutter delete is my next objective.

I have some data somewhere but I think it was 35mph where they shut (obviously dependent on parameters) and then they opened again as I was coming to a stop. Even with my 174F katech coolant thermostat, I was still seeing 190s + for ECT. Once the shutters opened my temps dropped.

Ditto on the trans temps. Much better with a pill flip but summer heat in AZ and towing can sometimes get up there a little

Edited May 11, 2022 by 14burrito

Ksz426 · May 11, 2022

Thanks 14burrito. I am in Phoenix, so yeah, the temps are tougher to deal with. I saw somewhere where someone removed some of the slats in the shutter, opening about half of it. If I were to do something like that, would I still need/want an extra cooler?
so many things to consider. Lol.

thanks again.

14burrito · May 11, 2022

15 hours ago, Ksz426 said:

Thanks 14burrito. I am in Phoenix, so yeah, the temps are tougher to deal with. I saw somewhere where someone removed some of the slats in the shutter, opening about half of it. If I were to do something like that, would I still need/want an extra cooler?
so many things to consider. Lol.

thanks again.

That is an option, as the flap motor will still have limits, therefore shouldn't register a code. The ATF cooler lines enter the condensor on the passenger side, and if memory serves correctly the ATF circuit in the condensor is the top 1/4 of it. So keep that in mind when removing vanes, youd want to remove the ones towards the top. That is if I recall the circuit correctly. It's worth a try for sure.

There in lies something to consider with an aux cooler and the K2 w/shutters...location and ATF line routing IF one was to add an aux cooler inline. The Mishimoto trans cooler seems to be mounted where the shutter vane assembly would otherwise be. For it to also be effective it would need to be mounted in front of that assembly.

Edited May 11, 2022 by 14burrito

PowerDr · December 19, 2022

Does anyone know if installing the new T-stat from the TSB with the "70" stamped on it would void an extended warranty? I have a 2019 with 42,000 miles on it. I have an extended warranty up to 82,000 miles. I would like to install the new TSB T-stat but I don't want to have an issue with the warranty if I have tranny troubles down the road.

Thanks