Transmission Thermostat Delete Pros vs. Cons

Grumpy Bear · August 9, 2020

8 minutes ago, truckguy82 said:

I’m more curious about the winter temps, i would have zero concern if it was summer all the time

Ask yourself if it hurt the 1963 to 2013 and earlier models, Powerglide to 6L80/90-E? Every GM automatic in every climate has had an unregulated cooler since late 1963 , passing through the radiator.

Why is the failure rate of pre 2014 6L80/80-Es lower than post? (newdude answered this fully)

Would GM design a failure?

https://w__.youtube.com/watch?v=iiCBYAP_Sgg

You were part of this exact same discussion in this thread:

6L80E thermostat delete sure-cool cooler kit

By Jdezee, November 30, 2019 in 2014-2019 Engine, Driveline, & Exhaust

Actually in ever such thread....

Grumpy Bear · August 9, 2020

16 minutes ago, rav3 said:

@truckguy.....This is a good question. With that said, I think it depends on how far you drive. Even before or after my thermostat delete, If I did a 15-20 min. drive, the temperature never got to a point that the thermostat would open up, so that drive wouldn't make a lot of difference on transmission temperature. I think yesterday morning when it was 68F outside it got up to maybe 120F. So, exactly how far do you need to drive to get the transmission fluid up to the "open thermostat" temperature?

If it's winter, the same case would apply. How far would you need to drive when it's 32 deg. F outside for either version to get up to say 130 F? It's my understanding that the temperature rise only comes from the friction created inside the transmission & not from, say, the temperature on the engine or radiator. Correct me if that's not the case.

So bottom line, what's the best temperature for the fluid? or the transmission? 140/150F? or 180/200F? And remember, as it's been pointed out earlier, pre 2014 trucks didn't have this thermostat, so theirs would be the same as the ones that did the delete mod.

FYI, yesterday evening, we drove up the Blue Ridge Parkway from 2100' elevation up to Mt Pisgah (5000') and the trans temperature was around 140F ish. Dropping down to 2200' elevation the temperature may have dropped to 135F. However, when I hit stop & go traffic while returning home, the temperature when up to 160F. I've never seen it that high so far since I flipped the pill.

As the cooler temperatures arrive this fall & winter, I'll be keeping an eye on the trans. fluid temp to see how it reacts.

Great observations. Keep your thinking cap on awhile longer.

This thermostat does not have a minimum flow bypass, it has in internal bypass back to the sump. In winter what heats the fluid? You already said it, internal work. Now with the thermostat deleted and constant flow through the radiator like it has since 1963 what heats the fluid? When does a cooler become a heater? When is it a cooler?

In physics, the second law of thermodynamics says that heat flows naturally from an object at a higher temperature to an object at a lower temperature, and heat doesn't flow in the opposite direction of its own accord.

Edited August 9, 2020 by Grumpy Bear

truckguy82 · August 9, 2020

1 hour ago, Grumpy Bear said:

Ask yourself if it hurt the 1963 to 2013 and earlier models, Powerglide to 6L80/90-E? Every GM automatic in every climate has had an unregulated cooler since late 1963 , passing through the radiator.

Why is the failure rate of pre 2014 6L80/80-Es lower than post? (newdude answered this fully)

Would GM design a failure?

https://w__.youtube.com/watch?v=iiCBYAP_Sgg

You were part of this exact same discussion in this thread:

6L80E thermostat delete sure-cool cooler kit

By Jdezee, November 30, 2019 in 2014-2019 Engine, Driveline, & Exhaust

Actually in ever such thread....

I’m not all that concerned with the reliability. I don’t doubt the cooler one has the edge there.

I’m mostly concerned with efficiency

if it’s 150-160 in the summer, and then 130 in the winter, I’d imagine 130 vs 190 has a pretty big difference in fuel economy

Grumpy Bear · August 9, 2020

1 hour ago, truckguy82 said:

I’m not all that concerned with the reliability. I don’t doubt the cooler one has the edge there.

I’m mostly concerned with efficiency

if it’s 150-160 in the summer, and then 130 in the winter, I’d imagine 130 vs 190 has a pretty big difference in fuel economy

The last two peaks are with my thermostat bypasses. Last year the entire summer averaged over 30.5 mpg. The first two winter troughs are thermostat in play and the last trough with it bypassed. It warms up much quicker and believe it or not, to higher AVERAGE fluid temperature. The second chart I present the same information by each 10,000 miles driven and indicated winter and summer bars by color.

In the four years I've tracked this truck I've learned that the single biggest mpg effect caused by any fluid is from the first number on the motor oil. That is there is little difference between a 5W20 and a 5W30. There is a marked difference between a 0W30 and a 10W30.

I expect in the way I did this that the majority of difference year over year came from the motor oil, which I am running around 30* cooler. I run a 170 F water stat instead of the 207 F factory piece.

Currently I'm running a 10W30 and have taken a hit on efficiency just as I expected. (not shown in these charts as I started a second set of books at 100 K). And I'm still over 29 mpg. DGI has really changed the way these things respond to changes.

Grumpy Bear · August 10, 2020

When you make comparisons of efficiency compare only to yourself. Does that need saying? I think so. Seems a humans nature to compare successes or accomplishments with our peers. We shouldn't. We all drive differently and we drive a different vehicle in different parts of the world. I think we also tend to look at trees in the forest instead of the forest. Longer views. You can learn more with patients and consistency. Kind of what habit means right? Habitual?

Part of how I enjoy my truck is this constant experimentation and analysis. Everything is reversible. But I don't do it haphazard. It has to make sense and I do prefer low risks. Anyway.....looking at the past use of coolers by the OEM's and the aftermarket keeps fears of this modification at bay.

mikbor1 · August 10, 2020

Curious if anyone had the issue I ran into—2014 High Country 4x4 5.3–flipped the pill in the thermostat just like everyone else, re assembled and was leaking bad from cap—took apart to see if I didn’t assemble correctly, all looked good—made sure half moon on cap was facing lines this time—installed again, same leak—tried a 3rd time, this time it shot the cap off and it landed on top of the transmission!, Took apart a 3rd time, re assembled back to factory setting, installed and works fine—- Any thoughts?

Eddie 70 · August 11, 2020

Spring in the bottom, pill flipped, then spring and cap, lastly snap ring.

Ltz4 me? · August 13, 2020

Is this transmission thermostat (pill)associated with a check engine light code p0711( transmission temperature sensor fault)

Or are these two different items on the transmission?

Epsilon Plus · August 14, 2020

On 8/10/2020 at 4:27 PM, mikbor1 said:

Curious if anyone had the issue I ran into—2014 High Country 4x4 5.3–flipped the pill in the thermostat just like everyone else, re assembled and was leaking bad from cap—took apart to see if I didn’t assemble correctly, all looked good—made sure half moon on cap was facing lines this time—installed again, same leak—tried a 3rd time, this time it shot the cap off and it landed on top of the transmission!, Took apart a 3rd time, re assembled back to factory setting, installed and works fine—- Any thoughts?

Look at the posts half way down on this thread.

https://www.gm-trucks.com/forums/topic/241614-silverado-6l80e-transmission-thermostat-delete/page/4/#comments

Eddie 70 · August 16, 2020

We finished our little running around. Made a 950 mile round trip and I don't recall the temp ever getting up to 190* even in wreck traffic. The majority of the time it was around 150-165ish range when running down the road. The truck still managed 22.6 MPG over this trip. No issues that I can tell. My lifetime average on the DIC shows 23.6MPG. So it is maybe down some on MPG. But at one point in the trip it was up to 23.0 on the DIC before we got stuck for a couple of wrecks on the interstate.

Grumpy Bear · August 16, 2020

34 minutes ago, Eddie 70 said:

We finished our little running around. Made a 950 mile round trip and I don't recall the temp ever getting up to 190* even in wreck traffic. The majority of the time it was around 150-165ish range when running down the road. The truck still managed 22.6 MPG over this trip. No issues that I can tell. My lifetime average on the DIC shows 23.6MPG. So it is maybe down some on MPG. But at one point in the trip it was up to 23.0 on the DIC before we got stuck for a couple of wrecks on the interstate.

Good news!!! :thumbs:

14burrito · September 24, 2020

For the few bucks, I ended up just buying a second unit making swapping much quicker. Curious to see what the change will be during DD. Fwiw, my t-stat was marked 180.

Edited September 24, 2020 by 14burrito

dwchapmanjr · September 24, 2020

On 8/12/2020 at 7:50 PM, Ltz4 me? said:

Is this transmission thermostat (pill)associated with a check engine light code p0711

Interestingly enough mine threw P0711 and then P0700 (which is what sets MIL when P0711 happens twice). I figured it was the failing temp sensor so I monitored with my dash gauge and scan tool and my temp sensor seems fine but what I noticed is my thermostat seems stuck open and it takes forever to warm up.

The conditions for when P0711 triggers are confusing but I did post this "question" on another forum -

From what am reading, P0711 is likely throwing a code because the ratio of temps is out of line. Maybe the collant temp warms up to 180-200 but the transmission is too cold and it expects it to be higher.

In any case, what's failed to be mentioned with this delete mod is that the TCM is calibrated for the higher temps and it shifts better at them which is why the thermostat is there in the first place. Its a performance and mileage thing. I don't believe the TCC will even lock up until around 70F. It wants 195F for smoother shifts.

Ltz4 me? · September 24, 2020

So if I "flip the pill" it's going to make my tranny shift worse b/c the TCM won't work well b/c it's not calibrated to this cooler tranny temp( oddly enough I just asked a question concerning this in a pm on here to a different guy, b/c in my head if I just delete tstat then how does the temperature sensor relationship work in conjunction with the TCM if it's still looking for 185 degrees and after delete it only gets up to 160?)

dwchapmanjr · September 24, 2020

9 minutes ago, Ltz4 me? said:

So if I "flip the pill" it's going to make my tranny shift worse b/c the TCM won't work well b/c it's not calibrated to this cooler tranny temp( oddly enough I just asked a question concerning this in a pm on here to a different guy, b/c in my head if I just delete tstat then how does the temperature sensor relationship work in conjunction with the TCM if it's still looking for 185 degrees and after delete it only gets up to 160?)

Well "not calibrated to this cooler tranny temp" may not be the right way to think of it. I imagine it has a sliding scale of pressures at various temps but it has better tunings and applies more appropriate pressures at the temp it has been optimized for (around 195F). At 160 its going to operate but with harsher shifts. I'm guessing it may not even use the shift adapts its learned at lower temps and just use the pre-set factory shift adapts at lower temps.

I plan on getting my thermostat fixed, I will let you know if it helps, although every time I take it in they do a fast relearn on it which usually fixes all my shift concerns for about 5 months. I drive so little and short trips I think my shift adapts just learn bad or don't learn all the clutches properly. Mine is a 2015 Yukon just breaking 38k miles.

Was your question about P0711 because you flipped it and got P0711 or just read about P0711? P0711 is usually triggered by a faulty or failed temperature sensor which is in the pan and connected to valve body. 2016 has a special coverage for 10 years , 150k miles on bad sensors because they apparently had a different "upgraded" design that was more prone to failure.