Brand New Sierra & Blown Transmission Cooler Line

[ATXSierra]

I've been lurking on the forum for a while, and have gained a lot of valuable information from everyone. I wish my first post was under better circumstances. I recently purchased a brand new 2018 GMC Sierra SLT with premium plus package. I've driven a Jeep for the past several years, and recently brought home a second german shorthaired pointer. It's hard to fit two kennels in a Jeep, let alone all of my hunting gear, so enter the truck. 

 

I was thrilled about the closeout deals on 2018 Sierras in my area, and here we are. It is a 5.3L with 8 speed auto. Yesterday I was driving home in traffic at about 50 mph. The truck currently has only 1000 miles. I see smoke out the back and begin losing power. Wound up in the center lane, still have oil pressure and engine is on... no power to the wheels in drive or reverse. Step out of the truck and see a long trail of fluid and then pool of red underneath the truck. I know its transmission. I called GM roadside and got a tow to the dealership in about an hour (kudos GM.)

 

This morning they get the truck into service and initially tell me it is a blown transmission cooler line. They state that they have ordered a new line and will throw that on there with new fluid and all will be good as new. 

 

What are your thoughts? I don't know how long I drove before the failure of the cooler line, but anticipate not very far given how fast it drained dry. I've already lost trust in this truck, and curious how to ensure either satisfactory repair or replacement. A new hose and flush, without opening the trans, makes me nervous. What potential damage could happen to the transmission in this circumstance? Thanks, y'all.

 

 

[SS502]

1 hour ago, ATXSierra said:

I've been lurking on the forum for a while, and have gained a lot of valuable information from everyone. I wish my first post was under better circumstances. I recently purchased a brand new 2018 GMC Sierra SLT with premium plus package. I've driven a Jeep for the past several years, and recently brought home a second german shorthaired pointer. It's hard to fit two kennels in a Jeep, let alone all of my hunting gear, so enter the truck. 

 

I was thrilled about the closeout deals on 2018 Sierras in my area, and here we are. It is a 5.3L with 8 speed auto. Yesterday I was driving home in traffic at about 50 mph. The truck currently has only 1000 miles. I see smoke out the back and begin losing power. Wound up in the center lane, still have oil pressure and engine is on... no power to the wheels in drive or reverse. Step out of the truck and see a long trail of fluid and then pool of red underneath the truck. I know its transmission. I called GM roadside and got a tow to the dealership in about an hour (kudos GM.)

 

This morning they get the truck into service and initially tell me it is a blown transmission cooler line. They state that they have ordered a new line and will throw that on there with new fluid and all will be good as new. 

 

What are your thoughts? I don't know how long I drove before the failure of the cooler line, but anticipate not very far given how fast it drained dry. I've already lost trust in this truck, and curious how to ensure either satisfactory repair or replacement. A new hose and flush, without opening the trans, makes me nervous. What potential damage could happen to the transmission in this circumstance? Thanks, y'all.

 

 

Did you happen to see what the Transmission temp gauge (oops sorry, that is through the DIC pages, I have the Denali cluster) indicated? I know it's not extremely accurate but maybe it crapped out on you before real damage happened. With all the folks who have had their transmissions worked on by various dealerships...not sure I'd even want them opening mine up. I totally understand your skepticism...I share your thoughts. I think they will do exactly what they said they will until it's proven that their "fix" didn't work. If it were mine, I would run that tranny through the ringer when they give it back and see how it reacts. The thing is, you can't make them do more until the "fix" fails. I would document everything and make sure the service MANAGER signs off on the "fix"...yeah have him put his name on the paperwork right beside the technician's signature.  

Edited December 18, 2018 by SS502
Added an oops

[ATXSierra]

Thanks, SS502. I checked trans temp right as I discovered the problem and it was 186.

 

Just got a call from service. The cooler line failed at the radiator. Said it was improperly fastened and/or not fastened? (Sketchy?) Good news is they replaced the line and, hopefully, connected it this time. With new fluid the tech said it "shifts OK" and will drive it a bit more and then confirm its OK for pickup.

 

I like the advice on putting it through the ringer. Fingers crossed. 

[SS502]

14 minutes ago, ATXSierra said:

Thanks, SS502. I checked trans temp right as I discovered the problem and it was 186.

 

Just got a call from service. The cooler line failed at the radiator. Said it was improperly fastened and/or not fastened? (Sketchy?) Good news is they replaced the line and, hopefully, connected it this time. With new fluid the tech said it "shifts OK" and will drive it a bit more and then confirm its OK for pickup.

 

I like the advice on putting it through the ringer. Fingers crossed. 

Well 186 is actually good, if even close! Keep us updated and best of luck, enjoy the truck most of us don't deal with the horror stories we read about, sucks for them and hopefully we don't join that club.

[wforrest08]

Sh!tty deal with the tranny line unfortunately it happens in the manufacturing process with ALL manufacturers odds are it was a bad crimp on the cooler line. If it were mine I’d a check under the truck when go to pick it up to see if they cleaned up the mess and since it’s a 8 speed I’d ask if the swapped all the fluid out or just filled it back up. The thread posted below talks about the latest and greatest “fix” for the shudder on these and apparently it’s new and improved Mobile One fluid be nice to know if your the first one on the block with the new fluid and might be helpful info for you in the future incase you ever develop that problem. If you make contact with someone from GM corporate over this might be worth seeing if you can get them to cut you a break on a GM extended power train warranty if your considering keeping this truck longer than the 5 year/60k.  Only reason I mention corporate is the second thread posted guy had a similar problem at 100 miles and was given a 750 dollar accessories gift card. Better than nothing I guess?

 

 

 

[ATXSierra]

On 12/18/2018 at 2:19 PM, wforrest08 said:

Sh!tty deal with the tranny line unfortunately it happens in the manufacturing process with ALL manufacturers odds are it was a bad crimp on the cooler line. If it were mine I’d a check under the truck when go to pick it up to see if they cleaned up the mess and since it’s a 8 speed I’d ask if the swapped all the fluid out or just filled it back up. The thread posted below talks about the latest and greatest “fix” for the shudder on these and apparently it’s new and improved Mobile One fluid be nice to know if your the first one on the block with the new fluid and might be helpful info for you in the future incase you ever develop that problem. If you make contact with someone from GM corporate over this might be worth seeing if you can get them to cut you a break on a GM extended power train warranty if your considering keeping this truck longer than the 5 year/60k.  Only reason I mention corporate is the second thread posted guy had a similar problem at 100 miles and was given a 750 dollar accessories gift card. Better than nothing I guess?

 

 

 

I wasn't aware of the shudder issues and hadn't experienced that yet, however interesting to note the Mobil1 fix. Thanks for sharing.

 

I confirmed with service and on my work order that they did use the new Mobil1 fluid. They essentially refilled because it was entirely empty.

 

Also have not yet contacted GM directly, but my thoughts were in the exact sam place with respect to an extended warranty. With this truck under 30 days old and 1k miles I already have doubts I'll keep past 5/60 if there is not an extended warranty in place. Accessories are never a bad thing either!

 

 

Edited December 23, 2018 by ATXSierra

[Demarco08]

My 2004 gmc sierra 1500 sle , transmission started slipping I took it to a transmission shop in New Jersey I paid 3500 for the transmission to be rebuilt . 6 days later the transmission line running to the radiator popped off while driving I instantly pulled over and got it towed back to the transmission  shop I was told the line blew to pieces but it’s fixed come get it two hours later it’s back to the original problem slipping 3/4 gear , I called the transmission shop and there making it sound like when the line popped I damaged the transmission when it popped I pulled instantly over I took it to another shop just now got it towed and they said it sounds like they messed something up and want to charge more money to fix it what do I do and how do I find out every step they took  and aren’t they liable