2018 GMC Sierra 1500

I have taken it in due to engine mounts 4 different times, transmission replaced and in October 2024 I took it in for issues I was experiencing like I had before my transmission went out. I did not get my truck back until almost Dec 2024 and that was due to there employee backing into the front end of my truck. So after all that my warranty was up Dec 24 2024 and then on April 16th 2025 I was driving my 2018 GMC Sierra 6.2l 1500 Denali 129,600 miles at approx 30 mph it was late so the streets were empty and we started to hear a knocking or what I thought at the time was a very bad exhaust leak. We parked and then we started to try to make it home very slowly which we did and it was not making to much noise. The next day I called GMC and explained they said bring it in. I towed it there to be safe but it did start and still ran at very slow speed. They called me and said that the lift side rockers/ lifters 1 failed and it was stuck due to a misfire and that the engine would need to be rebuilt and sent me over some very vague break down which looked like a lump sum price. I requested and better break down and got a screen shoot and that when he said that’s the best they can do. There were no engine lights on or warnings nothing at all. It also just got serviced at GMC for an oil change on February 27th 2025 along with some air filters. Today is April 29th and still waiting for the service manage to call and see if they can do anything to help out instead of charging full price. I will Attach pictures of the cost break down if possible. Thank you

Transmission just would not go them all of a sudden it jersey really hard in second gear an start to pick up speed..cold starts it change gear really hard in second gearc often times slipping then going into gear really violently.. need fix asap dealer has service once with the issue, change fluid an stopped a while ago now issue is back an worst then before.. 44,785 vehicle should not operate this way.4×4 awd trans starts at 6500 to replace an go up to about 13200 to replace

The contact owns a 2018 GMC Sierra 1500. The contact stated that while attempting to accelerate from a stop, the vehicle failed to accelerate while depressing the accelerator pedal. No warning light was illuminated. The vehicle was taken to a local dealer, and the transmission was repaired under warranty. The contact stated that a year after the repair was completed, the failure reoccurred. The vehicle was not repaired after the most recent failure. The manufacturer was made aware of the failure. The failure mileage was approximately 94,600.

When I first bought my 2018 GMC Sierra with the 8 speed transmission it would shift hard from first to second gear. Then at around 58,000 miles my truck also started to have a vibration coming through the steering wheel around 45-55 mph. I took it to the dealership and they changed the transmission fluid and did a software update. I am now at 80,000 miles and my truck still shifts hard from first to second gear and makes a grinding sound when accelerating sometimes. I am afraid to drive my any long distances for fear of the transmission malfunctioning. I have not been back to the dealership since my truck is no longer under warranty. So the problem has not been reconfirmed by a dealer or independent service center or inspected by the manufacturer. There have been no warning lamps or messages or other symptoms. I hope that GM is held accountable for putting a faulty 8 speed transmission in my truck.

My starter quit at 81,000 miles. It has always been a bit weak starting, but I have never had a starter go out on a vehicle at 81,000. I have replaced it, and the rebuilt starter is better than what was ever on this vehicle. I am also having problems with the transmission shuddering, shifting rough in low gear, and sometimes it reverses fast. Repair shops won't even touch the transmission. The dealership stated they couldn't get the problem to replicate the issues even though they know there are issues with the 8 speed transmissions.

Electrical system turns off power steering while driving Dashboard lights up like a Christmas tree service track service brake stability Had this service back in 2022 August the problems have resurfaced there are no recalls have spent lots of money and still failing Spent almost a year at the dealership fast forward to years later the same problem is occurring I am running out of money

When accelerating (at times) truck will shudder. Sometimes barely noticeable, sometimes violently. Was told by dealership that torque converter is going out and will be $4000 to replace but may not even fix issue. Looking online, appears that MANY (1,000’s) people are having same issue and that there is even a class action lawsuit about this issue. But no investigation by NHSTA yet, even though I can see many many complaints of similar issues