2015 8 Speed Transmission 1st Gear Slip

[lbenson]

Have 175k on my 2015 Denali with the 6.2L and the 8 speed. Engine runs like a dream. Transmission did until Friday when my local dealer flushed it at my 45k interval. Picked it up and got half mile down the road, it was slipping really bad and grinding. Took it right back after a couple miles and they told me the technician didn't add enough fluid back into it, missing half a quart they claimed. Picked it back up and then it was totally fine driving all weekend and towing my boat. In fact super smooth.

Made it 3 miles this morning and at my first complete stop it slipped out of first gear into 2nd and then right into 3rd. It was making the same rattle/hum/noise it did when there was not enough fluid. Pulled into a lot to confirm it did it. Instead of returning to IN from MN (650 miles) I drove straight to the dealer that did the flush. Took service advisor in quick drive in lot and he heard noise and felt the shift issue. Waiting now for them to call but probably won't be until tomorrow.

Has anyone had issues like this? Or is it possible they ruined my transmission Friday by not putting enough fluid in it and letting me take it for a few miles?

Any input/advice is greatly appreciated. Thank you all!

 

[avalonandl]

OMG, 1/2 quart low...BS that baby was way low IMHO. Did you check the level yourself?

 

[lbenson]

OMG, 1/2 quart low...BS that baby was way low IMHO. Did you check the level yourself?

Cannot check the level easily on the 8 speed. No dip stick for the 8 speeds (dumb). Gotta get it up on a lift and do some check with the two holes.

I call total BS on it being half a quart too. No way it made it shift that badly in "limp" mode.

 

[Tiredmechanic23]

OMG, 1/2 quart low...BS that baby was way low IMHO. Did you check the level yourself?

Agreed with this. 1/2 quart wont cause running issues at all. Most are that low to start with after a service till warmed up to check and fill to level.

A tech screwed up and cost you a trans it was way low or empty. You would not be a Karen/Kyle to pull the you touched it last card on this one.

 

[lbenson]

Agreed with this. 1/2 quart wont cause running issues at all. Most are that low to start with after a service till warmed up to check and fill to level.

A tech screwed up and cost you a trans it was way low or empty. You would not be a Karen/Kyle to pull the you touched it last card on this one.

Possible they just forgot to fill it too. Spoke with the service manager and got him involved this afternoon. He hadn't heard of the tech's mess up. Admitted it was human error and would look more into it.

I already am pulling the you touched it last card on this one. No way it wasn't their fault. Damn thing was fine when I dropped it off.

And I did giggle at the Karen/Kyle card joke.

 

[Tiredmechanic23]

Possible they just forgot to fill it too. Spoke with the service manager and got him involved this afternoon. He hadn't heard of the tech's mess up. Admitted it was human error and would look more into it.

I already am pulling the you touched it last card on this one. No way it wasn't their fault. Damn thing was fine when I dropped it off.

And I did giggle at the Karen/Kyle card joke.

Lol glad you got a giggle out of that. But yeah forgetting is still a tech screw up. Accidents happen though and even the best make mistakes. Its all in how they handle it. Looking forward to updates on how this ends up going.

 

[CMoore711]

First off; Glad to hear that at 175K your L86 6.2L 8-speed truck is still running good prior to this recent transmission issue after service.

Also am interested to see how they handle this. Would be really surprised if they replaced your transmission for absolutely free. But at your mileage even if they split it with you 50/50 I think that’s be a win. But I’d still push for 75/25 or 70/30.

Is the servicing dealer also where you purchased this Denali from?

 

[lbenson]

First off; Glad to hear that at 175K your L86 6.2L 8-speed truck is still running good prior to this recent transmission issue after service.

Also am interested to see how they handle this. Would be really surprised if they replaced your transmission for absolutely free. But at your mileage even if they split it with you 50/50 I think that’s be a win. But I’d still push for 75/25 or 70/30.

Is the servicing dealer also where you purchased this Denali from?

Fingers crossed it's something simpler than a full transmission replacement but if it is, I hope I could get one for free. But I doubt it at this point.

I bought the truck used a while back. Was in great shape and well maintained by the original owner. They had originally bought it at the dealer servicing it but I had found it at another local dealer when I bought it. I believe all their service was performed by the dealer that has it now (CarFax report said so). Hopefully being on top of maintenance and keeping it clean will only help my case.

Had the service bulletin for the 8 speed fluid performed 45k miles ago, but even then I really just experienced harder shifts. Never had what others described as it being driving over constant rumble strips.

 

[lbenson]

Update:

Dealer verified it was not a heat shield or exhaust rattle and that it indeed is coming from the transmission. Tried to a first get us to pay the $175 transmission diagnostic fee but we got them to agree to at least pay that to start.

They're going to drop the tranny and tear it apart now. Most likely will not know until later this week. Of course 1 of 2 transmission techs is on vacation all month...

Then we will go from there to determine the failure, whole new tranny, torque converter or some pump.

 

[Tiredmechanic23]

Update:

Dealer verified it was not a heat shield or exhaust rattle and that it indeed is coming from the transmission. Tried to a first get us to pay the $175 transmission diagnostic fee but we got them to agree to at least pay that to start.

They're going to drop the tranny and tear it apart now. Most likely will not know until later this week. Of course 1 of 2 transmission techs is on vacation all month...

Then we will go from there to determine the failure, whole new tranny, torque converter or some pump.

Thing is if it was the converter then a whole tranny would be best as the metal from it will get into everything and ensuring its all out and clean is difficult even when trying to do it well.