2017 6.2L, 8l90, 4wd longevity

[2017gmcsierraslt]

I have a 2017 6.2L 8l90 4wd with max tow.

I experienced the clunking when taking off and stopping sometimes lurching forward.

They said that was normal operation as well and that it was learning my driving and would smooth out.

Wanted to ask how everyone else's 2017 truck is holding up with the 6.2l and 8speed .

 

Edited October 4, 2022 by 2017gmcsierraslt

[2017gmcsierraslt]

Forgot to mention the transmission flush has stopped the shudder for now.

[pokismoki]

DO NOT used DexOS2 0w-20 oil,  use 5w-30 or 10w-30. change it at 4000 miles

remove thermostat from trans if it has one,  

change engine t-stat to a 170

 

Edited August 28, 2022 by pokismoki

[pokismoki]

i also installed and Aux trans filter, 

 

be sure to use the correct oil filter for the engine, there are two versions, one is low pressure bypass and the other is higher pressure.  using the wrong one might damage the motor too

[2017gmcsierraslt]

Thanks for the reply. I am using the 0w20 oil and I didn't know about the 2 different oil filters.

Is it the low or high pressure bypass we are supposed to use for the 6.2 liter?

Thanks again

 

[Blbstack]

2015 6.2 with 8l90 high country 150,000. Same issues with the trans. Clunking when shifting from park to reverse. Gears slamming when downshifting or slowing down. Almost like the trans does not know what gear it wants to be in. Once you get driving everything seems to get along and drive fine. But that initial startup and shift is violent lol. Had trans flushed and did absolutely nothing. Part of me wants to have new torque converter, steels and frictions put it in and the other side of me says just drive it till she won’t anymore. 
 

the life of a GM owner 

[2017gmcsierraslt]

Thanks for the reply blbstack. 

I was considering doing upgrades to the transmission but the fluid change stopped the shudder and is shifting much smoother.

The 1st to 2nd clunk is rare now and seems to be normal. 

 

 

 

Edited September 21, 2022 by 2017gmcsierraslt

[Cocheese1128]

I just picked up a 2017 Denali 6.2 with the 8L90 just over a month ago.  Noticed the same things on the shifting.  Delayed from Reverse to Drive, and Park to Reverse or Drive.  The clunking was noticeable too, but I'm new to the 8 speed and this body style (went from an 09 Tahoe 5.3 with 6 speed).  Just over a week and a half ago, the P0711 code came on for the trans fluid temp sensor.  Carried it to the dealer and thankfully I got an extended warranty.  They pulled the pan and found metal in there and said the torque converter was bad.  Now i'm waiting on them to source a new tranny and torque converter.  Been in the shop a week today.  Good times!

[Blbstack]

Cocheese1128;

 

what was the outcome of the trans? Were they able to source parts or just a reman? Shop near me (central Michigan) couldn’t find any parts for the 8l90…

 

I’ve just dealt with the clunking and slamming, probably just ride it out until it no longer moves at this point.