6L90 torque converter shudder

scole · December 23, 2021

I have a 2017 GMC Sierra 2500 HD w/6.0L Vortec and 6L90 transmission. At about 69k miles it threw a code P0741 and would not shift into overdrive. Dealer replaced the torque converter, dropped the pan to check for metal debris. Reported no debris. Less than 500 miles later it developed the shudder in the torque converter. Took it back to the dealer for service. They said it was bad torque converter, they would replace it and it was ok to drive until the replacement came in. Dropped it off a couple days later, picked it up a couple days after that. Within a day it developed the same shudder in the torque converter. Took it back to dealer, they verified the issue, said it was another bad torque converter and would need to be replaced. They again said it was perfectly fine to drive until the part arrived. I expressed concern about debris being created and causing harm to the rest of the transmission. They said there was no risk of harm to the rest of the transmission. After a couple more days they shudder was so bad I was concerned about getting stranded somewhere so I dropped off the vehicle at the dealer. I spoke with the lead tech and again asked about debris coming off the bad torque converter. He said that type of problem was not causing debris but he said they would drop the pan and inspect again. I asked to be called so I could see as well, for some sleep insurance.

My concern and question is whether or not severe shudder will result in debris that requires service in addition to replacing the torque converter. Other opinions about this service experience welcome also.

Thanks,
-Steve

mjm-1957 · December 23, 2021

Have the dealer drive it with GDS 2 installed and command the tcc off 100% and note if the shudder still occurs. I am bettting the 456 clutch is slipping, not the converter. Three defective ones in a row??? Doubt it. I am the transmission guy at a GMC Buick dealer and have seen this before. They can also monitor the slip speed with the GDS while commanding the TCC on 100 %, will tell them which way to go.

scole · December 23, 2021

I'll pass that info along to the lead tech. There was no shudder with the original torque converter. The symptoms with the original one was it failed to upshift into high gear/overdrive after it warmed up and it threw the P0741 code. The shudder only started with the 2 replacement units and dealer said they've had the same problem with another vehicle. They are trying to get a replacement from a different source.

90Nine ForOne · June 7, 2022

I'm experiencing the same issues with our 2016 2500HD. It's only noticeable when the transmission temp is around 180 deg. Shifting is perfectly fine at lower temps. What was the solution/fix that the dealer came up with?

scole · June 7, 2022

It had a severe shudder even after the 3rd torque converter. They dragged their feet and mid February they eventually decided the transmission was not maintaining the correct pressures (I think that's what they said) and ordered a new transmission. It took over a month to get it to the dealer. It was installed late March and haven't had any issues since.

90Nine ForOne · June 7, 2022

Wow! I was kind of afraid of that but it makes since, since the issue only occurs at higher temps. Thanks for the response.

scole · June 7, 2022

I don't know what the temps of my transmission were but I could get in it first thing in the morning on a 40 degree day and within a mile of easy driving it would start to shudder.

pokismoki · June 7, 2022

PR valve failure, TCC o-ring is leaking, did they install low temp GM t-stat yet?

newdude · June 8, 2022

14 hours ago, pokismoki said:

PR valve failure, TCC o-ring is leaking, did they install low temp GM t-stat yet?

6L90 doesn't have the thermostat 15-19. They added one for 2020.

STEERMTD · June 15, 2023

Hi, I have a GMC Savanah with a 6.0L engine and a 6L90 transmission. Purchase brand new in September 2019. In November 2019 we contacted the dealer with 1000 miles on the vehicle about a shutter or hesitation at lower speeds, especially going up hill. It has been to 4 dealers since, and no solution. 17K miles on it. The only thing was at dealer 3, he changed the torque converter. Now it shifts a little different, or it did in the beginning.

We are at a loss. GM did extend the bumper to bumper 1 year, so September that's over. I really don't know what the solution is. Get rid of it and purchase a new one? Other than this problem it's perfect for us.

Dealer 4 has it now, he cannot find anything wrong. It's crazy really. No codes, ever!

scole · June 15, 2023

After 3 months, 3 "new" torque converters and many days without my vehicle, I called GM Customer Care and got them involved. Shortly after that GM and dealer decided to replace the transmission. No problems after that. The official diagnosis was transmission was not maintaining proper fluid pressures, I think that's what they said.

Scotty1269 · June 17, 2023

Afternoon all, I've been having the same shudder/vibration rumble strip noise with my 2015 Silverado 1500 for about 6 months now. I bought the truck new in 2015 and have not had a problem besides general maintenance stuff to this point (110K). I first started noticing a hesitation or lag when shifting and or accelerating, then it progressed into a shudder/vibration noise and usually happens at around 40 mph and then at 70 mph. Letting off the gas or accelerating will stop the shudder. I did a trans fluid flush at around 100k as part of general maintenance. My mechanic kept the truck for a few days to diagnose. He narrowed down to the torque converter, just like many posts on this topic. Initially he thought we would replace just the converter but now he is now suggesting a transmission replacement vs just a torque converter as he thinks it may not solve the problem and that metal shreds may have been circulating into the transmission. After reading your post I'm leaning towards the replacement. Did you ever happen to find out if the torque converter problem had caused damage to the transmission in anyway?

scole · June 17, 2023

14 minutes ago, Scotty1269 said:

Afternoon all, I've been having the same shudder/vibration rumble strip noise with my 2015 Silverado 1500 for about 6 months now. I bought the truck new in 2015 and have not had a problem besides general maintenance stuff to this point (110K). I first started noticing a hesitation or lag when shifting and or accelerating, then it progressed into a shudder/vibration noise and usually happens at around 40 mph and then at 70 mph. Letting off the gas or accelerating will stop the shudder. I did a trans fluid flush at around 100k as part of general maintenance. My mechanic kept the truck for a few days to diagnose. He narrowed down to the torque converter, just like many posts on this topic. Initially he thought we would replace just the converter but now he is now suggesting a transmission replacement vs just a torque converter as he thinks it may not solve the problem and that metal shreds may have been circulating into the transmission. After reading your post I'm leaning towards the replacement. Did you ever happen to find out if the torque converter problem had caused damage to the transmission in anyway?

The original problem which started the circus on my truck was the trans lost overdrive. There was no shudder, noise or other symptoms except it would not shift up into overdrive. When the dealer replaced the torque converter, they said they inspected for debris but found none. Of course, now I'm skeptical whether they checked or how thorough they were. That's when the shudder started. No shudder when I brought it in for original problem. Shudder began within a day or 2 of getting truck back. The shudder is a widely known issue with these GM vehicles. It's well documented and but GM is unwilling to admit the problem. I guess it is possible for the torque converters to indeed be the problem, like perhaps none of the new or rebuilt torque converters are exactly the same as the ones installed at the factory and when mated with the original transmission, they just don't work correctly. Dunno. I was fortunate enough to have a an extended warranty in place which paid for all the service work. I feel sorry for those who don't.