2017 Yukon Denali Shudder Problem

[cirrusaviator]

Hey there,

I picked up a 2017 Yukon Denali with 60k miles on it from Carmax two days ago. I didn’t notice it during the test drive, but I’m experiencing a shudder that feels like driving over rumble strips.

I went back to Carmax yesterday morning, and they knew exactly what I was talking about. They said they would send it to GMC to perform a transmission fluid flush. If that resolves the issue, I should be good. If not, they would replace the torque converter.

My question is: if the flush is successful, should I expect the car to run fine for a while, or is this issue likely to reoccur after a few thousand miles?

We love the car otherwise, but we’re concerned.

Is there anything else with this model I should be thinking about?

Thank you!

 

[B-train]

I have the exact same vehicle. I bought it with 41k and had the shudder at 43k. The fluid flush works magic. I now have 162k on it and it's been great. Make sure to keep the fluid changed every 40k. I usually change the filter every 80k.

The fact that they offered to replace the TC is huge. Just keep good records. If you can get a flush out of it and a new TC, you'll be good for MANY miles.

My only concern from the whole deal would be HOW long has it been doing this with 60k on the clock. The fluid basically causes the TC to experience sticky spots due to the moisture that's trapped in the fluid - hence what you feel.

 

[cirrusaviator]

I have the exact same vehicle. I bought it with 41k and had the shudder at 43k. The fluid flush works magic. I now have 162k on it and it's been great. Make sure to keep the fluid changed every 40k. I usually change the filter every 80k.

Thank you! That's encouraging to hear.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[cirrusaviator]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Thank you! I will for sure be active in the forums. Our first GMC vehicle. I'll have to take more pictures from different angles soon.

 

[B-train]

Thank you! I will for sure be active in the forums. Our first GMC vehicle. I'll have to take more pictures from different angles soon.

I like that color and wheel combo. Mine is white tri-coat with the double spoke 22 inch wheels. They are nice rigs. I've (mostly my wife) has enjoyed ours for 120+k. Good power, good mpg, and nice creature comforts. I hope you have many miles of good use!

 

[kk1lron]

Along this thread I have seen mixed advice for this issue. One is flush the fluid and life is good. Other is time for a torque converter. I am kind of a fan of try the less expensive way first.

2015 Yukon XL here.

I have also experienced a occasional shudder which started happening around 112k miles. It had been quite subtle and maybe once to a few times in a 10 mile drive 30MPH to 60MPH (around town and bi-ways). Then last week the truck acted like it was in neutral except Park which worked. After the truck sat for several minutes I started it again and was able to drive (in the driveway), but not for long before when coming out of park it was neutral in any position. It did go into gear after sitting again and I parked it waiting for a tow to my mechanic.

When the tow truck arrived to take the truck I started it and there was a bit of a whiny noise from underneath the truck (it had not been run for a week) which lasted 10 seconds or so, then normal (this sound was not the short whistle-skreetch right at start which is pretty common). I was able to drive the truck onto the bed of "tow" vehicle.

Does this sound like a flush to fix, or a new TC situation? Any hints I should give the mechanic? It is on his schedule for Thursday.

THANKS!

Y'all like pics, so here ya go.

 

[B-train]

Along this thread I have seen mixed advice for this issue. One is flush the fluid and life is good. Other is time for a torque converter. I am kind of a fan of try the less expensive way first.

2015 Yukon XL here.

I have also experienced a occasional shudder which started happening around 112k miles. It had been quite subtle and maybe once to a few times in a 10 mile drive 30MPH to 60MPH (around town and bi-ways). Then last week the truck acted like it was in neutral except Park which worked. After the truck sat for several minutes I started it again and was able to drive (in the driveway), but not for long before when coming out of park it was neutral in any position. It did go into gear after sitting again and I parked it waiting for a tow to my mechanic.

When the tow truck arrived to take the truck I started it and there was a bit of a whiny noise from underneath the truck (it had not been run for a week) which lasted 10 seconds or so, then normal (this sound was not the short whistle-skreetch right at start which is pretty common). I was able to drive the truck onto the bed of "tow" vehicle.

Does this sound like a flush to fix, or a new TC situation? Any hints I should give the mechanic? It is on his schedule for Thursday.

THANKS!

Y'all like pics, so here ya go.
View attachment 442893

I'd check the fluid level. My wife explained a similar issue on our 8 speed with 162k. It ended up being a little low on fluid per my friend at the dealership. I ended up replacing the trans temp harness, filter, and fluid. Been fine since. Hoping for 200k out of it.

 

[kk1lron]

I'd check the fluid level. My wife explained a similar issue on our 8 speed with 162k. It ended up being a little low on fluid per my friend at the dealership. I ended up replacing the trans temp harness, filter, and fluid. Been fine since. Hoping for 200k out of it.

Thanks for that comment B-train. I had checked the fluid level (running cold) and was right in the hashes. The rig is in the hands of the shop today and we'll see what someone far more skilled than I finds.

 

[JMH1980]

Thanks for that comment B-train. I had checked the fluid level (running cold) and was right in the hashes. The rig is in the hands of the shop today and we'll see what someone far more skilled than I finds.

If you have a dipstick to check fl you I'd level, it's probably a 6L80 Transmission. The vehicle is going into a safety lock up because there are internal problems. I'm not an expert, but might be looking at a rebuild/replace situation, from what I've read on other threads.

 

[cirrusaviator]

Quick update: I took the car back to CarMax, and they sent it to a GMC dealer. The dealership said they’ve never seen a shudder this bad before and will be replacing the transmission.

GMC also wants to replace some rear suspension components, bringing the total cost to a little over $10k. Frustrating, but I’m hopeful that the car will run smoothly after these fixes.

Fortunately, CarMax is covering all the costs.

 

[tom3]

It's good that Carmax stepped up and is fixing it, but pretty bad that GM transmissions are such crap these days.

 

[cirrusaviator]

It's good that Carmax stepped up and is fixing it, but pretty bad that GM transmissions are such crap these days.

I was surprised. The service tech and manager were on top of it, which was unexpected. Plus, they ordered all new brakes and rotors and are replacing all four tires. The service tech has been calling me almost every day with updates.

Yeah it's our first GMC vehicle.

 

[17_EmeraldDenali]

I literally signed on this morning because we started to experience the shutter recently. It actually had the shutter when we bought it 6 years ago with about 60k miles on the clock. Took to my local dealer where a buddy of mine works, he did the flush, and haven't had a problem since.
In the last week or so the shutter has become more prominent. I'm really hoping a fluid flush, filter change will do the trick but I'm preparing for a possible TC change.
I haven't noticed any issues with the operation of the transmission yet, just the shutter. What are the odds the transmission could need to be rebuilt? And how much are good shops typically charging for this. I have the 8 speed.

 

[kk1lron]

If you have a dipstick to check fl you I'd level, it's probably a 6L80 Transmission. The vehicle is going into a safety lock up because there are internal problems. I'm not an expert, but might be looking at a rebuild/replace situation, from what I've read on other threads.

This seems like the right answer. My mechanic despite knowing this was likely a transmission issue, just drove the vehicle then recommended I take it to our local transmission expert. Should have done that to start, since I waited 10 days for the appointment.
The local trans experts had the truck evaluated pretty much the day I dropped it off (Friday afternoon and got a call Monday before noon). "The whine you are hearing is the pump and probably will need a rebuild. $500 for us to drop the trans and check things out. If you continue with the needed work the $500 applies". I will know more tomorrow...or maybe later today.

 

[JMH1980]

This seems like the right answer. My mechanic despite knowing this was likely a transmission issue, just drove the vehicle then recommended I take it to our local transmission expert. Should have done that to start, since I waited 10 days for the appointment.
The local trans experts had the truck evaluated pretty much the day I dropped it off (Friday afternoon and got a call Monday before noon). "The whine you are hearing is the pump and probably will need a rebuild. $500 for us to drop the trans and check things out. If you continue with the needed work the $500 applies". I will know more tomorrow...or maybe later today.

There are some upgrades for the 6L80. From my research for my own transmission, an 8L90, I've found thG Transgo and Sonnax have kits for the GM platforms. Also recommended to upgrade the converter to a billet at the very least. Whether you keep it at the stock specs or increase the stall, is up to you. Slightly higher stall converter can be fine for stock applications.

 

[kk1lron]

There are some upgrades for the 6L80. From my research for my own transmission, an 8L90, I've found thG Transgo and Sonnax have kits for the GM platforms. Also recommended to upgrade the converter to a billet at the very least. Whether you keep it at the stock specs or increase the stall, is up to you. Slightly higher stall converter can be fine for stock applications.

Just got the call from the trans folks. Full rebuild. With "upgrades", TC, etc, etc. $7k. Ugh.

 

[kk1lron]

Just got the call from the trans folks. Full rebuild. With "upgrades", TC, etc, etc. $7k. Ugh.

Work complete! Super fast TAT. The shop is FULL aware of all the upgrades and has applied them. They have been doing lots of 6L80s (I think he said 5 a month) and keeps all the parts in stock. Happy about the service. Barry's Transmission Specialists, South Burlington, VT.

I should add that after the rebuild I no longer hear a short skreetch at startup. That had been reported as a starter noise by some on "the Internet". Maybe it was my transmission?? Or maybe reassembling the trans to the engine squared that away?? Not complaining

 

[tom3]

Son had about the same experience, little cheaper here in Applachia. Shop owner said it used to be Mopars that kept him busy, now it GMs with the 6 and 8L failures. So far his has been perfect.

 

[kk1lron]

Work complete! Super fast TAT. The shop is FULL aware of all the upgrades and has applied them. They have been doing lots of 6L80s (I think he said 5 a month) and keeps all the parts in stock. Happy about the service. Barry's Transmission Specialists, South Burlington, VT.

I should add that after the rebuild I no longer hear a short skreetch at startup. That had been reported as a starter noise by some on "the Internet". Maybe it was my transmission?? Or maybe reassembling the trans to the engine squared that away?? Not complaining

I have driven about 150 miles on the rebuilt trans. I pretty consistently get a short "weeep" (1/2 second ish) when gently accelerating from about 33MPH after having slowed gently from about 40MPH. I do not hear this at any other similar speed transition. I called the rebuild shop and was told it is the TC clutch reengaging and that it could take 1000 miles before that goes away. I also figured that is where the noise originated, but wonder if the "wait 1000 miles" comment is valid or not.