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Im sorry, but it is kind of funny GM 21-NA-199


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Plenty of discussions with the dealer and techline in regards to the operating temps that GM set forth on the powertrain for our Tahoe. They said both engine and gearbox temps were normal and as expected...

 

I ended up doing a Katech 174 and trans thermo pill-flip about a year ago and have been much more happy ever since.

 

And now this is released for the gearbox...

https://gm-techlink.com/?p=15389

 

Little bit of irony.

Edited by 14burrito
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This is the kind of data that to me reenforces that the "make sure to only use the factory parts and factory spec'ed fluid, because the engineers always get it right" is a very blind sentiment. I am not saying aftermarket is always better, but I am convinced that the water pump I replaced has lasted longer than the original, that the Amsoil Transmission fluid that is not officially approved by GM makes the 8speed transmission much better behaved, that the 5-30w oil used in other GM v8 engines is much better protection than the 0-20w the manual calls for, that lowering the engine thermostat and removing the transmission thermostat will improve the life of both, and that adding an oil catch can will help reduce fowling and carbon build up. Even if GM claims otherwise, or didn't spec that from the factory. I only wish I had done all of this in the first 500miles and not over the 60k it took me to change it all up. 

 

Your milage may vary, but I bet mine will be longer if you stick to stock. 😉 

Glad to see GM finally addressed this in the 6speed. Wonder why they don't cover the 8speed. 

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On 11/10/2021 at 10:51 AM, 14burrito said:

Plenty of discussions with the dealer and techline in regards to the operating temps that GM set forth on the powertrain for our Tahoe. They said both engine and gearbox temps were normal and as expected...

 

I ended up doing a Katech 174 and trans thermo pill-flip about a year ago and have been much more happy ever since.

 

And now this is released for the gearbox...

https://gm-techlink.com/?p=15389

 

Little bit of irony.

There goes that debate

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On 11/10/2021 at 10:07 PM, ftwhite said:

This is the kind of data that to me reenforces that the "make sure to only use the factory parts and factory spec'ed fluid, because the engineers always get it right" is a very blind sentiment. I am not saying aftermarket is always better, but I am convinced that the water pump I replaced has lasted longer than the original, that the Amsoil Transmission fluid that is not officially approved by GM makes the 8speed transmission much better behaved, that the 5-30w oil used in other GM v8 engines is much better protection than the 0-20w the manual calls for, that lowering the engine thermostat and removing the transmission thermostat will improve the life of both, and that adding an oil catch can will help reduce fowling and carbon build up. Even if GM claims otherwise, or didn't spec that from the factory. I only wish I had done all of this in the first 500miles and not over the 60k it took me to change it all up. 

 

Your milage may vary, but I bet mine will be longer if you stick to stock. 😉 

Glad to see GM finally addressed this in the 6speed. Wonder why they don't cover the 8speed. 

 

They'll get to the 8 spd once it get's closer to the end of it's life cycle.

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Lowering the thermostat temperature for the engine can often times require a re-program of the ECU to recognize what full operating temperature should be.  Yes, the engine should essentially operate at the same operating temperature as before because once the thermostat is fully open, you'll get there anyway.  However in the winter time, especially, it will take much longer, and in certain climates that are very frigid, may never reach there.

I'd imagine with a computer controlled transmission that retrieves data in regards to fluid temperature, that a similar re-program would be necessary for optimal performance.  I don't see that referenced anywhere in this TSB.

These computer controlled vehicles are sensitive to changes like these unlike vehicles from 40 years ago.

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31 minutes ago, BlaineBug said:

Lowering the thermostat temperature for the engine can often times require a re-program of the ECU to recognize what full operating temperature should be.  Yes, the engine should essentially operate at the same operating temperature as before because once the thermostat is fully open, you'll get there anyway.  However in the winter time, especially, it will take much longer, and in certain climates that are very frigid, may never reach there.

I'd imagine with a computer controlled transmission that retrieves data in regards to fluid temperature, that a similar re-program would be necessary for optimal performance.  I don't see that referenced anywhere in this TSB.

These computer controlled vehicles are sensitive to changes like these unlike vehicles from 40 years ago.

 

 

If a reprogram was necessary, GM would have included one in the TSB.  

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12 minutes ago, BlaineBug said:

Lowering the thermostat temperature for the engine can often times require a re-program of the ECU to recognize what full operating temperature should be.  Yes, the engine should essentially operate at the same operating temperature as before because once the thermostat is fully open, you'll get there anyway.  However in the winter time, especially, it will take much longer, and in certain climates that are very frigid, may never reach there.

I'd imagine with a computer controlled transmission that retrieves data in regards to fluid temperature, that a similar re-program would be necessary for optimal performance.  I don't see that referenced anywhere in this TSB.

These computer controlled vehicles are sensitive to changes like these unlike vehicles from 40 years ago.

 

I've been using a Reische Racing 170 F thermostat in an IPSCO holder for years now. Pill flipped the TBV. Added pan volume to the 6L80 and filled every hole it has with Red Line HP/AMSOIL lubricants. 

 

On a 90 F day the trans runs 163 F. The water temperature runs 173 F and the oil temp about 192-198 F and will stay there all day. It did not and does not require a tune. I've averaged 28 mpg over 150,000 miles. It uses no oil. It does NOT take longer to reach 173 F no matter what thermostat you use as long at it is working properly. Closed is closed. It just throttles lower IF you have enough radiator to maintain your new set point under the service you ask from it. The pill flip actually gets the trans temp over 104 F FASTER than the factory thermostat which does not have a minimum flow bypass requiring all heat be generated from use. Before the flip that may take 50 miles or more in the winter. Now around 10 in the winter and 3 or less in the summer. 

 

On a 30 F day the water runs 173 F, oil 188-190 F and trans about 125-130 F. Gets better than 25 mpg and acts just like it does in the summer.

 

Now having said that. IF I towed, and I don't, I would add both more radiator and more trans cooler and tune the fan switch points. Dead stalled in traffic it is at the mercy of the fan switching temperature. Hint; in the summer if you leave the AC on at the coldest setting and the blower on the lowest the radiator fans will turn on much earlier than 215F. Mid 180 range.  

 

IF you use a 160 F water thermostat THEN you will need some tuning but the 170 F Reische or 174 Katech or 180 F Stant does not. IF the transmission temperature stays above 104 F the TCM/PCM programs are satisfied. 

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On 11/10/2021 at 10:51 AM, 14burrito said:

Plenty of discussions with the dealer and techline in regards to the operating temps that GM set forth on the powertrain for our Tahoe. They said both engine and gearbox temps were normal and as expected...

 

I ended up doing a Katech 174 and trans thermo pill-flip about a year ago and have been much more happy ever since.

 

And now this is released for the gearbox...

https://gm-techlink.com/?p=15389

 

Little bit of irony.

 

 

End of the day it all came down to CAFE/Fuel economy ratings.  The faster the trans got to operating temp, the faster it could produce less friction, the faster it gets better fuel economy.  

 

Now that GM no longer makes K2, and they are obviously seeing a warranty costs increase on 6L80 failures, they decided to make their own fix that everyone else already knew was the cure to lots of 6L80 failures, the "thermostat" being at 194F for the trans.  07-13 6L80's never had one, and have much less of a failure rate.  98% of the 6L's we've taken out of trucks at work are 2014-2018.    

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7 minutes ago, newdude said:

 

 

End of the day it all came down to CAFE/Fuel economy ratings.  The faster the trans got to operating temp, the faster it could produce less friction, the faster it gets better fuel economy.  

 

Now that GM no longer makes K2, and they are obviously seeing a warranty costs increase on 6L80 failures, they decided to make their own fix that everyone else already knew was the cure to lots of 6L80 failures, the "thermostat" being at 194F for the trans.  07-13 6L80's never had one, and have much less of a failure rate.  98% of the 6L's we've taken out of trucks at work are 2014-2018.    

Just like cylinder deactivation is all the rage for kool aid drinkers. With the chip shortage they have to admit that it’s good for a mile per gallon in certain situations. All that potential component failure costing thousands and overall lowering the reliability of the engine. Good for GM, bad for costumers. For the outliers who drive in controlled situation and change their oil more than should be necessary it may be great. 

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1 hour ago, newdude said:

 

 

If a reprogram was necessary, GM would have included one in the TSB.  

I'm still not convinced.  The same could be said about a lower transmission operating temperature being "best" would have been included in the initial build to begin with.

It would take a vehicle data logging expert to speak on these matters regarding changing thermostat temperature for engine coolant and transmission alike.  That's not me.  But I know the temperature is read by the computers and can't be just for nothing.

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2 hours ago, BlaineBug said:

I'm still not convinced.  The same could be said about a lower transmission operating temperature being "best" would have been included in the initial build to begin with.

It would take a vehicle data logging expert to speak on these matters regarding changing thermostat temperature for engine coolant and transmission alike.  That's not me.  But I know the temperature is read by the computers and can't be just for nothing.

 

 

The 6L80 has been pretty much the same unit since 2007 other than small upgrades along the line for added HP from newer engines.  2007-2013 they ran no thermostat on the trans lines.  The 6L90 from 2007-2019 in the HDs have no thermostat either.  Having owned a 2012 1/2 ton, a 2015 HD and now a 2019 old body 1500, the transmissions in all three (including the thermostat bypass in mine) all operate the same exact ways throughout various operating temperatures.  

 

Fuel economy was the driving factor, pretty much period.  They had beating the 2013s as a goal, as well as competition.  Trans thermostat, 75w85 high efficiency gear lube, 0w20 motor oils.  All of those came for the EPA gains.  07-13 trucks were still on 5w30, 75w90 gear oil and had no thermostats on the transmissions.  Other than the occasional AFM lifter failure (and bad rusting in the salt states), those trucks are quite reliable.    

 

Heat kills transmissions.  GM knows and knew this, hence the lower temp thermostat.  The all mighty warranty costs is why this new valve exists.  

 

 

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3 hours ago, Grumpy Bear said:

 

If 150K miles trouble free doesn't convince you....then you can't be convinced and I'll stop trying. 

 

 

 

I understand cooler temps are better for longevity.  But my point is, is it really running "optimally" considering the factory firmware is programmed to see the input from a thermostat of a different value?  That's what is yet to be determined.  And it has already been proven that this can most certainly cause an issue when it comes to engine coolant thermostats.  As I said in colder climates especially.

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4 hours ago, newdude said:

 

 

The 6L80 has been pretty much the same unit since 2007 other than small upgrades along the line for added HP from newer engines.  2007-2013 they ran no thermostat on the trans lines.  The 6L90 from 2007-2019 in the HDs have no thermostat either.  Having owned a 2012 1/2 ton, a 2015 HD and now a 2019 old body 1500, the transmissions in all three (including the thermostat bypass in mine) all operate the same exact ways throughout various operating temperatures.  

 

Fuel economy was the driving factor, pretty much period.  They had beating the 2013s as a goal, as well as competition.  Trans thermostat, 75w85 high efficiency gear lube, 0w20 motor oils.  All of those came for the EPA gains.  07-13 trucks were still on 5w30, 75w90 gear oil and had no thermostats on the transmissions.  Other than the occasional AFM lifter failure (and bad rusting in the salt states), those trucks are quite reliable.    

 

Heat kills transmissions.  GM knows and knew this, hence the lower temp thermostat.  The all mighty warranty costs is why this new valve exists.  

 

 

I'm not saying that having NO thermostat or a COOLER thermostat is an issue.  I'm saying that the programming is set for one or the other.  As you say the 2007-2013 models did not have a trans cooler line thermostat.  But the firmware was programmed for as such.

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7 minutes ago, BlaineBug said:

I'm not saying that having NO thermostat or a COOLER thermostat is an issue.  I'm saying that the programming is set for one or the other.  As you say the 2007-2013 models did not have a trans cooler line thermostat.  But the firmware was programmed for as such.

 

Lets try a little logic 101. Yea I said I wouldn't but you don't seem to be trolling. 

 

Obviously you motor runs just fine when you first start it up on a cold day and continues to run just fine all the way to fully warm. Correct? All along the way there are, as you expect, 'triggers'. Yes some of those are temperature. And what is happening is that the ECU is programed for each set of possible conditions to run "Optimally" In other words as long as some minimum values are met the tune it supplies is the best tune for that set of inputs. Those points or minimums for transmission and water temp I mentioned in a earlier post. 160 F water is the minimum temperature the fuel map will go full lean i.e. 

 

Unless your logging one may never know that transmission and oil temperatures vary a pretty good amount base on load and regardless of the thermostats wishes. A thermostat set a 'floor' but not a ceiling. 

 

IF you saying that there is a single 'perfect' temperature for best efficiency I again offer 150 K miles of fuel logs that would argue otherwise.  

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