Something for you guys with the late model GM trucks

Discussion in 'The BS Topic' started by Knuckle Dragger, Dec 2, 2021.

  1. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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

    Trans thermostat issue. We are seeing a lot of burn up transmissions and odd trans behavior.

    The repair is not covered under warranty. Should be simple to see which thermostat you have
     
    M1 Master Gunner and Dave Nelson like this.
  2. fbody_mike

    fbody_mike Veteran Member

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    Thanks for the info. I have a 2020 Suburban, it was a late in the year manufacture so hopefully mine has a 70 on the bottom of the bypass. If not do I then proactively change it, or wait for issues.
     
  3. biker

    biker Veteran Member

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    This is gold. Thanks man.
     
  4. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    If it were me I'd change it. The fluid in the Tahoes is very dark with under 36k on them.

    I should have a part number for you guys shortly.
     
  5. djorgensen3

    djorgensen3 Veteran Member

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    I followed a vid on YouTube to disable that t-stat on my Silverado a few years ago and then added an additional trans cooler and it never gets over 154 degrees even in our summers. It runs real cold in the cooler months but before I did the mod, it would never get below 194 and would get up to 240 degrees pulling a trailer up Sunset Point. I'm glad I did the mod. It also makes it easy to do a trans fluid change now...which I think I am do for again....gahhhh.
     
  6. Batman

    Batman Administrator Staff Member Lifetime Gold Member

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    So Dave, for my 2015 Sierra, will I need to change the cooler lines as well as someone on the gm-techlink mentioned, or should I be good? Probably should have the fluid changed, since the truck has 145K miles on it!
     
  7. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    Valve part number is 86774933, seal is 23135703. We have not been able to get a GM part number for the o-rings at the lines. We have either reused the old ones or generic o-rings from a bulk kit.



    Your truck is not listed in the bulletin, I wouldn't worry about it. I personalty don't believe trans flushes do anything positive for modern transmissions. The fluid is generally rated for 100k+. Anymore I believe they are just part of the wallet flush mentality of repair shops. Always consult your owners manual, they may have a different option on this, and I'm sure someone will post up to tell me how wrong I am. :)


    The city did a study shortly before I hired on. They found no significant extension of transmission life by doing the services every 60K as set up in the maintenance schedule at the time. We no longer do transmission services.
     
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  8. 1980RS

    1980RS Veteran Member

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    I wonder if that was causing the Chevy shake all along on those trucks.
     
  9. biker

    biker Veteran Member

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    I've never seen a flush do anything good for an auto trans. In fact, most go the other way for some reason. I like dropping the pan and filter and refilling with new. But as KD says above, new vehicles probably just dont benefit from that anymore.
     
  10. chevyJeff1

    chevyJeff1 Veteran Member

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    Was this study only for the fleet trucks that you specialize in? Or a general study on automatics, including cars..?
     

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