2018 centennial edition w/ 7500 miles, torque converter shudder at low throttle application.... new transmission??

WeberKettleGuy · September 26

Truck has a low throttle shudder, certainly feels like a torque converter shudder from my experience with vehicles. This is a 2018 Silverado 6.2 with the 8 speed auto. The truck only has 7500 miles on it. I called the dealer today to inquire if the transmission fluid was ever replaced under the TSB, and it was not. The truck is out of all the warranties except for the aftermarket warranty we still have on it. When I inquired with the service manager about doing the fluid flush, he said that his experience with these, the torque converter is already damaged. The service manager said that the warranty company would probably replace the entire transmission. He then asked how many miles were on it and was noticeably shocked when I told him 7500. Then he remembered the truck because it had all the lifters replaced under warranty 400 miles ago.

So, Do what do you guys think? If the warranty company wants to replaced the entire trans should I let them? Do I have a choice in the matter? and will it be a new trans, or a remanufactured unit? Of course the truck will have to go to the dealer and get diagnosed, but I'm pretty confident we all know the issue is from the original fluid never being replaced.

JimCost2014 · September 26

The 8 speeds are a pretty stout transmission, I would change the fluid and drive it for a while.

If the TC is truly damaged, the shudder will return quickly.

rav3 · September 26

I agree with JimC^^^ But research the Mobil 1 LV ATF HP, there's a BLACK & BLUE label & I believe one supersedes the other.

ohed · September 27

I had a similar problem. My 2018 was preowned and developed a shudder. Since this was a certified preowned truck it was under warranty. I requested the Mobil 1 fluid change however the dealer said according to their records it already had Mobil1 so they replaced the torque converter. No more issues !!!

TNTSierra · September 27

One of the MAIN reasons I bought my certified 2018 Denali with then 37k miles on it was because on the Carfax it stated it had the TQ converter replaced and fluid change. If your truck is under warranty and the warranty department will cover a whole new transmission. Why not get it done and done the right way?? We all know these 8 speeds in the K2 models had their issues.

Back in 2018 when I bought my SLT, the ONLY reason I got rid of it was because of the 8 speed shudder and clunking! My dealership wasn't working with me, and already did the transmission flush, so I was just over 36k miles, so I traded it in for a 2019 High Country. Grew to not like the truck except for the 10 transmission. Glad I sold it during pandemic and made money, then found this lightly used 18 Denali. I love this body style and the truck

You have a gorgeous truck, I love that color/combo package. I had a chance to get one of these Centennial Editions last year in March 2023 with 520 miles on it in Arkansas, but it had the 5.3L not the 6.2L. Once you have a 6.2L, in my opinion you can't go back! Good luck with your decision.

newdude · September 27

20 hours ago, WeberKettleGuy said:

Truck has a low throttle shudder, certainly feels like a torque converter shudder from my experience with vehicles. This is a 2018 Silverado 6.2 with the 8 speed auto. The truck only has 7500 miles on it. I called the dealer today to inquire if the transmission fluid was ever replaced under the TSB, and it was not. The truck is out of all the warranties except for the aftermarket warranty we still have on it. When I inquired with the service manager about doing the fluid flush, he said that his experience with these, the torque converter is already damaged. The service manager said that the warranty company would probably replace the entire transmission. He then asked how many miles were on it and was noticeably shocked when I told him 7500. Then he remembered the truck because it had all the lifters replaced under warranty 400 miles ago.

So, Do what do you guys think? If the warranty company wants to replaced the entire trans should I let them? Do I have a choice in the matter? and will it be a new trans, or a remanufactured unit? Of course the truck will have to go to the dealer and get diagnosed, but I'm pretty confident we all know the issue is from the original fluid never being replaced.

Change the fluid. Have them do the TSB flush and the shudder will go away.

Changing the converter won't fix the fluid shudder, nor is your converter damaged. 6 speeds are the ones where the converter will be damaged.

You have 7500mi on a 2018, high probability that original formula HP fluid has absorbed some water as that was what started the whole shudder issue was the fluid was too hygroscopic.

Edited September 27 by newdude

WeberKettleGuy · October 1

Thanks for the replies! I tried to reply last week, but the forum was being wonky. Anyways, I was going to take it to the dealer last week, and it started misfiring, real bad. Bad enough to trigger the flashing check engine light. So I called the warranty company and the dealership. It was towed yesterday morning from my driveway, I just don't want to chance any more issues on the drive over. This is my first truck with AFM, and even with the lifters just being replaced 500 miles ago, I'm worried the misfire is more than a coil or plug.

When I spoke to the service writer about getting the TSB done on changing the fluid, He said that it's out of warranty. It's been a minute since I've had to deal with a TSB, but if it's out of the factory warranties, can the dealer opt to not perform them? They want like 300 dollars to do the flush and change out of pocket.

In the end, I guess the jokes on them since they will have to deal with the warranty company and figure out what needs to be done. I just hope they spend their time on it and don't run it through like a cattle barn.

I'll keep you all posted. It's not "scheduled" to be diagnosed til friday.

newdude · October 1

3 hours ago, WeberKettleGuy said:

Thanks for the replies! I tried to reply last week, but the forum was being wonky. Anyways, I was going to take it to the dealer last week, and it started misfiring, real bad. Bad enough to trigger the flashing check engine light. So I called the warranty company and the dealership. It was towed yesterday morning from my driveway, I just don't want to chance any more issues on the drive over. This is my first truck with AFM, and even with the lifters just being replaced 500 miles ago, I'm worried the misfire is more than a coil or plug.

When I spoke to the service writer about getting the TSB done on changing the fluid, He said that it's out of warranty. It's been a minute since I've had to deal with a TSB, but if it's out of the factory warranties, can the dealer opt to not perform them? They want like 300 dollars to do the flush and change out of pocket.

In the end, I guess the jokes on them since they will have to deal with the warranty company and figure out what needs to be done. I just hope they spend their time on it and don't run it through like a cattle barn.

I'll keep you all posted. It's not "scheduled" to be diagnosed til friday.

TSBs aren't a warranty only repair. They would apply to customer pay as well. Technical Service Bulletin.

We just did a 2016 Yukon Denali with the 8 speed for a shudder at 49,000mi, fluid fixed it. Customer pay.

Edited October 1 by newdude

TNTSierra · October 2

On 10/1/2024 at 9:28 AM, newdude said:

TSBs aren't a warranty only repair. They would apply to customer pay as well. Technical Service Bulletin.

We just did a 2016 Yukon Denali with the 8 speed for a shudder at 49,000mi, fluid fixed it. Customer pay.

That to me is CRAP!!!!! This is a known issue that these 8 speeds have. GM and the dealerships should ALL come together and cover this for LOYAL customers. No-one should have to pay for this. That to me is just sh@tty customer service, and this is coming from a man whose father was a mechanic for 40 years!!!!!!!!!!!! So I have seen first hand the in and outs of loyalty, quality, and customer care

newdude · October 2

1 hour ago, TNTSierra said:

That to me is CRAP!!!!! This is a known issue that these 8 speeds have. GM and the dealerships should ALL come together and cover this for LOYAL customers. No-one should have to pay for this. That to me is just sh@tty customer service, and this is coming from a man whose father was a mechanic for 40 years!!!!!!!!!!!! So I have seen first hand the in and outs of loyalty, quality, and customer care

The dealers have nothing to do with covering anything, that's on GM.

The fluid swap was being handled under powertrain warranty if it was still active, so 2020-2021 would be the most recent years still covered, and then late purchased 2019 model year (anything the warranty went active on post today). Anyone just outside of powertrain could try via the dealer for GM assistance.

As for GM covering all 8 speeds for fluid change under special coverage? Unlikely but anything is possible. I'd imagine the majority of 8 speeds have had the fluid changed by now. 15-19 Corvette are probably the least likely to have as they don't get driven like most other vehicles.

Edited October 2 by newdude

WeberKettleGuy · October 6

Repair update: it's fixed..... kinda....

The service writer that I communicated with was very understanding, and I do feel gave me the time of day in my concerns/complaints. One plug and wire later, the misfire is certainly taken care of. Bad plug was in cylinder 4. The tech swapped the plug and wire to another cylinder to rule out a bad coil, and misfire followed the bad plug. Again, I'm shocked that a plug with only 7k miles is bad, but it is 7ish years old. So $370 later ($150 diagnostic fee, $150 labor rate and the most expensive spark plug I've ever paid for in my life), I have it back.

Service writer and two techs (one being the transmission guy) ensured me that there is no issue with the trans and torque converter. They all drove it, putting 10 miles on it. After I drove it home, I still have a low rpm/low throttle shudder around 50mph once the truck is up to operating temperature. I'm on the fence about taking it back, but I'll probably just start with changing the trans fluid myself. No way I'm paying them the crazy rates for a fluid swap, especially if the warranty company is gonna pull the "maintenance item" crap again. I'm also gonna change the other 7 plugs and wires just to rule them out, since one went bad already. Side note, they wanted another $300 to change the other 7 plugs! And of course the aftermarket warranty didn't help, since plugs and wires are a maintenance item. At least my insurance company will take care of the tow bill.

As far as the TSB and customer pay stuff goes, My two cents is GM should have taken care of it and just changed the fluid. They know it was an issue, but want me to be stuck with the cost? Not cool. Even if the dealer has to "take care of it", I'm sure there is some reimbursement from daddy GM somewhere. At the end of the day, this is one of the many reasons why people hate using dealerships for their repair work.

JimCost2014 · October 7

Think the fluid flush would be worth the money, you existing fluid is contaminated with water, so if you don't get it all out and mix the new fluid with the old fluid, you will probably end up contaminating it too.

As far as the TSB's, how long do you feel they should last? Not being an Ahole, but if someone stores a car for twenty years, then decides to drive it, should it still be warranted? I know my answer is no, at one point all responsibilities of your vehicle fall on the owner.

TNTSierra · October 7

Interesting. When I bought my 2018 Denali last June, I added an extended warranty on it. Bumper to bumper 5 years or 100k. Covers everything! Why doesn't yours do that?

Either way I would change the fluid ASAP. Will make a difference for you. Good luck.

WeberKettleGuy · October 7

11 hours ago, JimCost2014 said:

Think the fluid flush would be worth the money, you existing fluid is contaminated with water, so if you don't get it all out and mix the new fluid with the old fluid, you will probably end up contaminating it too.

As far as the TSB's, how long do you feel they should last? Not being an Ahole, but if someone stores a car for twenty years, then decides to drive it, should it still be warranted? I know my answer is no, at one point all responsibilities of your vehicle fall on the owner.

After reading the sticky about changing fluid and flushing, It sounded like the flush on these trans wouldn't work like it used to on older models. I suppose I need to do more homework and ask more questions. And I don't think you're being an Ahole, you make a valid point with timeframes. My view on this is it's a known issue, and should immediately pop up in the dealers computer when the VIN is ran for repair. GM knew it was an issue and issued a TSB to correct it. If it was anything to do with safety, it would have been a recall, not a TSB. The truck went into the dealer last winter and had all the lifters replaced due to a single collapsed lifter. That would have been the time to catch it, however I don't know for sure if it had the shudder. It was first noticed by my father in law when it came home from that repair, but wasn't ever driven afterwards until my father in law passed away in June, which was the first time I drove it.

The warranty I have on it is an aftermarket warranty, not a GM extended warranty. I did not purchase the truck as a "certified pre owned" or anything to that effect, so no chance of having any GM warranty left, since the original purchase was back in 2018, all the GM warranties have expired. The aftermarket warranty was purchased at that time, and is a 96 month warranty.

newdude · October 7

6 minutes ago, WeberKettleGuy said:

After reading the sticky about changing fluid and flushing, It sounded like the flush on these trans wouldn't work like it used to on older models. I suppose I need to do more homework and ask more questions. And I don't think you're being an Ahole, you make a valid point with timeframes. My view on this is it's a known issue, and should immediately pop up in the dealers computer when the VIN is ran for repair. GM knew it was an issue and issued a TSB to correct it. If it was anything to do with safety, it would have been a recall, not a TSB. The truck went into the dealer last winter and had all the lifters replaced due to a single collapsed lifter. That would have been the time to catch it, however I don't know for sure if it had the shudder. It was first noticed by my father in law when it came home from that repair, but wasn't ever driven afterwards until my father in law passed away in June, which was the first time I drove it.

The warranty I have on it is an aftermarket warranty, not a GM extended warranty. I did not purchase the truck as a "certified pre owned" or anything to that effect, so no chance of having any GM warranty left, since the original purchase was back in 2018, all the GM warranties have expired. The aftermarket warranty was purchased at that time, and is a 96 month warranty.

The fluid TSB - 18-NA-355 1..17 (nhtsa.gov)

TSBs are not recalls or field updates. Recalls and field updates will attach to a VIN in GM's system. TSBs are just diagnostic aids.

Edited October 7 by newdude