? On t.s.b bulletin

[Scott1212]

Does Gm have t.s.b  bulletin on transmission thermostat change to a lower tempt ? 
if so dose anyone have the # of it thanks Scott 

[newdude]

Yes 158F.  21-NA-199.

[Scott1212]

Says it came out on oct 6 th 2021 then underneath that it says it no longer available,called dealerships today they said there wasn’t any bulletin on my issue? He said he’d  ask and came back saying ,there were no bulletin on my issue,thanks for reaching out ,any other info would be great ,

[14burrito]

Changed from 180 to 135.

 

21-NA-199

 

You could do a pill flip or order a new t-stat and ensure it's stamped with a "70" on the housing. 

Edited January 31, 2022 by 14burrito

[14burrito]

More details here with a link to the TB

 

https://www.gm-trucks.com/forums/topic/253735-im-sorry-but-it-is-kind-of-funny-gm-21-na-199/

[Scott1212]

Thanks again..

I have an appointment Thursday,service manager said bring it in so they can check the drive train for codes ,mention to him it shifts sluggish,late shift..and noticed Tran tempt was around 190plus ,,this is after driving on the highway for 3,4 hrs ,I’m sure they aren’t gonna go for a long drive to try to duplicate the complaint,truck still under drive train  warranty,asked if there was any bulletins  on issue,he checked with someone there and came back saying there was none.just don’t want to throw $125 out the window for a dia..problem not found  at this time lol ,any advice would be great .thanks again Scott 

[Scott1212]

Didn’t know if I should just go and buy the up dated one ,and put the money towards that new one ,or flip it like you had mentioned.looks pretty simple to replace.

[14burrito]

1 hour ago, Scott1212 said:

Didn’t know if I should just go and buy the up dated one ,and put the money towards that new one ,or flip it like you 

 

Very easy to replace. Lot of info in the other thread in regards to torque specs, etc. Honestly, I flipped the pill and would do that again. I'm actually looking into what's linked below to allow for better flow.

 

https://lincodieselperformance.com/shop/ols/products/ldp-l5p-trans-cooler-bypass-valve

[mikeyk101]

190⁰ with OEM thermostat is pretty normal according to how it works. But with the new thermostat, it would definitely be lower by 30-40⁰ minimum.

 

The new thermostat takes about 10 mins of your time and is pretty simple to do. IMHO, this is the best way to go.

 

The pill flip is a bit more involved but doable. Because of the retainer clip that needs to be removed to get the cap off, you really need 3 hands to do it, LOL. And getting that cap and retainer clip back on is also a bit of a challenge. 

[Scott1212]

Thanks guys for all the info much appreciated 

Scott