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New GM TSB for Thermal Bypass Valve

I order this for my 2016 Silverado 1500 6 speed a week ago, arrived yesterday, and installed it today.

Let my say this right off; I've done the "pill flip mod" on the OEM valve and it works great in the warm months. Cruising down the road, temps would average 50-60*F over ambient outside air temps according to the DIC in my truck. However; now that Fall is really here, there were/are times my tranny temps barely topped 100*F according the DIC. Trans shifted and acted totally normal at the lower temps, but if we see -0*F and lower, I don't know what would happen if anything.

Anyhow; once installed and up to temp, transmission stayed in the 144-147*F range in my 30 mile loop around suburbia in 45*F outside temps. Even with the OEM 194*F stat, my trans would run usually run 180-185*F. So this kinda corresponds with those numbers.............New 158*F stat and tranny running 144-147*F. I like it.

JFYI also..............I am running the Corvette/Camaro 194*F engine stat vs. the OEM 207*F one. No discernible difference in mileage or performance.

Later.
 

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2018 Silverado LTZ
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I am having the new (70c) thermal bypass installed this coming week at the dealership. Installed at no-charge at the dealership under the 50,000 mile power train warranty. I simply showed the service writer the TSB-he checked with the service department manager and they ordered the part out of Denver. I tow a 5,000 pound travel trailer all over the country-and even since new it's been the "sloppy six speed". I am wondering if maybe I will see smoother more concise shifts?
 

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I just had the service bulletin with the 70c thermal bypass valve done three weeks ago at the dealer on my 17 Silverado 1500 5.3l 6spd. Put on about 1200 miles since then and the temps stay in the mid to upper 140’s now. I towed around 2500-3000 pounds for a few days and the temps stayed below 160. Transmission used to run between 190-210 degrees before having the new thermal bypass service bulletin done. Outside temps have ranged between 35-60 degrees since having it installed. I have a programmer for my truck and have it tuned so I couldn’t tell any difference in shifting as the tunes had already fixed the poor shifting on my truck.
 

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...Trans shifted and acted totally normal at the lower temps, but if we see -0*F and lower, I don't know what would happen if anything.
They run just fine without a thermostat, GMT900s don't have them.
 

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2022 LTZ northern blue
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114 Posts
Did the superior solutions bypass kit on mine 1 month ago.
Dropped the temp and have noticed that the trans shifts much smother than it ever has.
will do a fluid filter change soon. Very happy with the results, we’ll spent $40
After putting about 1000 on the truck I can honestly say that the transmission is shifting smoother. I haven’t noticed any difference in mpg. Wish this mod would have been available years ago
 

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But didn't they hit the radiator prior to the cooler??? My 2016 tranny cooler lines go straight to the cooler/condenser unit in front of the radiator.
Yes, I believe that the K2s put the external cooler into the upper portion of the AC Condenser. The thermostat does away with routing the fluid into the radiator.
 

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2016 Silverado
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I modified the thermal bypass valve on my 2016 Silverado 6L80E transmission using the Superior Transmission valve rebuild kit. My transmission fluid temperature around town used to run 191°. Now it is holding at 144°.
 

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I had brought one and wanted to try it if it would fit the 14 model. Come to find out it doesn't work on a 14 model. The tranny lines are different.So I just modified the original one so that it flows all the time.
I have over 91000 miles on it now. I tuned the tranny since it was new and changed the oil twice already. no issues,pan was like new inside,but I figured it would help even more my running the tranny at a cooler temperature. I should have done this sooner, but better late than never I guess. lol...
 
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