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Transmission Thermostat Delete Pros vs. Cons

Eddie 70

By Eddie 70
in Engines & Drivetrain

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jaimeastin Enthusiast

jaimeastin

Posted
Posted

@Grumpy Bear and everyone else.

 

I have a 2018 Silverado 5.3 6L80.  I did the thermostat delete last year after noticing temps going from 180 average to 190 towing in the summer.  I dropped the pan/filter and changed fluid.  I just did another pan drop, but this time added a pan with a drain plug so I can change fluid more frequently.  

 

Question... do we need to add more fluid to the trans than to the cold mark since the thermostat is gone?  I ask because, when I originally did this, i filled to cold mark.  Ran through the gears, drove it to warmer tems (140s is high as it will get during that time)... Then added more to stop any slight whine or anything else.  Never had an issue... I just think i over filled it.  It is always over the hot...

 

I am doing quick little drain and fill again because i think the drain bold might have a leak, but i want to make sure i fill it back right.  Filling what I took out, is usually about how it goes because I fill the new containers back up.

 

What are your thoughts?  I drained all my fluid down to the cold mark this morning.  

 

THank you in advance.

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11bravoZ71
11bravoZ71

Results are in    STL010 average open highwaytemp is 140 Heavy city use  is up to 197f  stays at around 197 if I idle for an extended period    flipped stock thermos

silveradosid
silveradosid

i did the flip on the weekend, i have 120k miles on my transmission. it was 82 f outside and i drove 80 mph for 30 miles and the temp stayed at 156. before it was always above 200. when it was above 2

14burrito
14burrito

Little 5 quarts ATF rejuvenation followed with the new ATF thermostat being installed. Curious to see if driveability will change at all and interested to see how ATF temps are altered.

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Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted

txab is on the nose. It needs to be on the hot mark when hot. Be sure to move through all gears for a few seconds each then check in park on level ground. The delete does NOT effect the fill volume at all. 

  • Like 1
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
5 hours ago, pokismoki said:

only issue doing a delete , is the transmission won't enter the trans re-learn/purge mode. you have to get it hot to activate this function with the scanner tool

 

That will need an explanation a five year old can follow. Pre 2014 6L80E boxes didn't have thermostats. My 2015's adaptive learning seems happy enough. BUT If "purge mode" means it cycles the thermostat...no loss there. It's always purging. 

  • Like 1
CamGTP Senior Enthusiast

CamGTP

Posted
Posted

To do certain functions on the transmission with a scan tool the temp needs to be high enough to activate that procedure. Without a thermostat it will take longer to get it there. I don't have the information off hand to know what the temps are for pre 2014 and post 2014 vehicles. Usually this stuff is for new TCM's, a rebuild and that sort of thing.

 

Throw the E-brake on and hold the throttle down some, that'll heat the fluid up faster lol

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Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
11 hours ago, CamGTP said:

To do certain functions on the transmission with a scan tool the temp needs to be high enough to activate that procedure. Without a thermostat it will take longer to get it there. I don't have the information off hand to know what the temps are for pre 2014 and post 2014 vehicles. Usually this stuff is for new TCM's, a rebuild and that sort of thing.

 

Throw the E-brake on and hold the throttle down some, that'll heat the fluid up faster lol

 

I can tell you that in stalled traffic that even with the pill flipped it will get to 200 F. Got caught in Interstate crash traffic two years ago. Even with my 170 F water stat it was kicking on the fans and drove oil and water temperatures into the low 200's. 

 

Just don't run the converter to the stall speed...right? 

 

  • Like 1
pokismoki Senior Enthusiast

pokismoki

Posted
Posted (edited)

yes as CAM said, just hold the ebrake, and the brake pedal down and full throttle her... the Torque management will take over and you wont go anywhere... just enough TM to heat the fluid up.

 

I've do it everytime I reprogram the transmission tables, re-learn and purge. this even make the stock factory tune shift better. I would recommend it after a filter and fluid drain but you will have to have the dealer do it if you dont own GM's  hardware or software to run the test.

Edited by pokismoki
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  • 1 month later...
Alec Kerchner Enthusiast

Alec Kerchner

Posted
Posted
On 7/30/2020 at 11:18 PM, Grumpy Bear said:

I did mine (pill flip) after the first winter and now have 123 K miles on it. Flawless miles. Mine runs colder than most as I also lowered the water thermostat to 170 F. And it still stays over the TCM minimum in the winter to 0 F. Want it warmer? Leave the factory 207 F water stat in place and your good to lower than it will turn over. I don't know how many times I've posted this in the dozens of related threads on this topic. 

 

Look, as Cameron noted earlier. This thermostat thing was NEW in 2014. As long as automatics have been around they've been radiator cooled without a stat. 

 

As far as fuel, even in the winter....I've logged every mile since I got it at 1300 miles in both states. It is more fuel efficient bypassed. Why? Because it heats the fluid until the fluid is warmer than the water. GM did not have the good sense to machine a minimum flow bypass into the casting like every other thermostat maker on the planet. That first winter it didn't get up to temperature for nearly 100  miles during the coldest months. Now she's up the heat in about 20 miles.  

 

TransTemp.thumb.png.026abb0e57c15a77d3ae332bdbbbfe88.png

Hey Grumpy, I noticed somewhere you mentioned you are in northern IL. Im due west of Rockford. It gets fairly cold as you know and this winter is supposed to be rough. You think I should have no issues flipping the pill on my 15'? Its a 6L80. Unknown what the maint history is at 101k miles. 

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
43 minutes ago, Alec Kerchner said:

Hey Grumpy, I noticed somewhere you mentioned you are in northern IL. Im due west of Rockford. It gets fairly cold as you know and this winter is supposed to be rough. You think I should have no issues flipping the pill on my 15'? Its a 6L80. Unknown what the maint history is at 101k miles. 

Issues from being cold? No. I'm 18 miles south of Rockford. Never have had an issue now nearing 150K on my 15. Here's the thing. It will get hotter stock but it will take forever to get there. It will be cooler with it flipped but get there quicker. It never hurt a transmission prior to 2014 so I can't think of a reason why it would now. Can you? 

  • Like 1
Alec Kerchner Enthusiast

Alec Kerchner

Posted
Posted
2 minutes ago, Grumpy Bear said:

Issues from being cold? No. I'm 18 miles south of Rockford. Never have had an issue now nearing 150K on my 15. Here's the thing. It will get hotter stock but it will take forever to get there. It will be cooler with it flipped but get there quicker. It never hurt a transmission prior to 2014 so I can't think of a reason why it would now. Can you? 

Nope! Ive added it to my list for the weekend. I appreciate it! I hardly take any trips longer than 10 minutes. I foresee all the benefits. 

  • Like 1
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
1 minute ago, Alec Kerchner said:

Nope! Ive added it to my list for the weekend. I appreciate it! I hardly take any trips longer than 10 minutes. I foresee all the benefits. 

 

That is pretty short. You likely won't even notice the difference in trips that short. You may benefit from changing your fluid to Red Line D6 which is PAO/Ester based and has exceptional cold flow numbers. 

  • Like 1
asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted

My experience doing this has been little to no change in operating temperature, especially while towing - which is why I did it in the first place. Towing in mid to upper 90's ambient temperature with a full load results in transmission running at 190-200 before and after. In my case the cooler isn't going to be able to cool the fluid down below what it was before. Having the thermostat flipped might cause it to warm up slower, but once its hot it'll stay there. So, now I'm considering an auxiliary cooler that can expel more heat than the factory cooler and take advantage of the defunct thermostat.

  • Like 3
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
13 minutes ago, asilverblazer said:

My experience doing this has been little to no change in operating temperature, especially while towing - which is why I did it in the first place. Towing in mid to upper 90's ambient temperature with a full load results in transmission running at 190-200 before and after. In my case the cooler isn't going to be able to cool the fluid down below what it was before. Having the thermostat flipped might cause it to warm up slower, but once its hot it'll stay there. So, now I'm considering an auxiliary cooler that can expel more heat than the factory cooler and take advantage of the defunct thermostat.

 

Absolutely correct. The cooler indeed has a thermal limit and if the load (towing) is higher than that limit it will still get hot. An additional cooler is warranted. If road speed (stalled in traffic on a hot day, 10 mph mountain pass) is to low it will still overheat. Additional air flow in the form of an ancillary fan such as a Derale Remote cooler with thermostatic fan would be a good call. 

 

Match the cooling to the load...yes! 

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