2018 GMC SIERRA 1500 Complaints

I own a 2018 GMC Sierra 1500 V8 5.3 liter which is at 46, 433 miles. Over the past few weeks I have noticed the transmission having difficulty shifting in first gear and lurching, and making shuddering noises, and as well making a constant ticking noise. After an experienced mechanic had put a diagnostic system onto my truck, his system diagnosed a Transmission Lifter Failure, specifically 2 out of the 8 lifters. A few days later (9-04-26) I took my truck to a certified GMC servicing business (Patriot Chevrolet of Hopkinsville KY 270-886-1207) and had a transmission servicing done. I had told the Customer Service representative Amanda Williams about the ticking and that I thought 2 lifters going bad in the transmission were the source of it. 3 hours later the servicing was done which cost $ 474.43. She did not know if the ticking had stopped or not. I started my engine to head home and the ticking was still happening. Nothing had changed. I got home, parked and have not started the engine since to minimize any further damage. I have become aware that this year, make and model has become infamous for the engine/transmission design and parts failure which has been at the center of thousands of class action lawsuits. I have owned this vehicle since inheriting it from my late father for 2 months before he developed dementia and suffered a broken hip. I have religiously had the oil changed every three months regardless of the mileage, and this is a sealed transmission which cannot be worked on by someone but a certified GMC mechanic, which wasn't a worry because the truck's manual says doesn't need to be worked on unless there seem to be problems. Which is what I did on 9-4-26, hoping that a servicing would fix the issue. During the 5 years that I have owned this truck, I never received ANY sort of notice from GMC that might've hinted at possible Transmission Failures, though GMC has been totally aware of. Sudden power loss dangerous and unfairly expensive to drivers.

Within the first 3 years of purchase as a new vehicle, my 2018 GMC Sierra Denali equipped with the GM 8L90 automatic transmission developed a pronounced judder during light acceleration, resembling driving over rumble strips. The condition was first reported to an authorized GMC dealer on October 23, 2021, at 26,648 miles while the powertrain warranty was in effect. GM authorized a transmission-fluid exchange from the technical service bulletin (TSB) 18-NA-355, dated April 2020, but that repair did not provide a lasting correction. The condition continued, and in 2026 the authorized dealer diagnosed an “internal stator issue causing judder on light acceleration” and recommended replacement of the torque converter. We completed the repair and retained the removed converter. The defect affected the vehicle while accelerating and created concern about predictable power delivery when merging, entering traffic or crossing an intersection. Continued torque-converter malfunction can generate heat and debris, damage the transmission and potentially impair acceleration or power transfer. GM had issued technical bulletins addressing torque-converter shudder in 2018 Sierra vehicles before this truck was purchased, but there has been no recall. I request that NHTSA evaluate whether this recurring defect presents an unreasonable safety risk in GM vehicles equipped with the 8L90 transmission.

Automatic Transmission not shifting properly unable to accelerate bangs gears while shifting noises from the transmission not reported no warning lamps

There was a mass recall on 2018 GMC Sierras to due to a faulty break pump vaccum. We are experiencing the same problems but for some reason were not included in the recall. We were told to reach out on here as others have to see what can be done as this is a saftety hazard.

Head gasket failure and overheating. After fixed, power steering has just failed during driving. Will have to have it towed to shop

THE FRONT PASSENGER SIDE SEAT BELT RETRACTOR IS FAILING TO RETRACT. I HAD A PASSENGER IN THE VEHICLE AND AS WE CAME TO A STOP IN MY DRIVEWAY TO EXIT THE VEHICLE SHE UNHOOKED (RELEASED) THE SEATBELT AND IT WILL NOT RETRACT. THE SEATBELT IS NOW CURRENTLY EXTENDED OUT AND WILL NOT RETRACT BACK INTO THE RETRACTOR. I PURCHASED THE VEHICLE TODAY 08-05-2026, I CALLED THE DEALER I PURCHASED IT FROM AND THEY STATE THAT THERE IS NO RECALL ON THE VEHICLE WITH THIS ISSUE. I DID LOOK THE ISSUE UP ON GOOGLE AND INFACT IS STATES A PROBLEM WITH THE SEATBELT RETRACTOR FOR MY VEHICLE. I SENT THEM A SCREENSHOT OF THE CONFIRMATION FOUND AND THEY DECLINE TO ACKNOWLEDGE A REPAIR STATING THERE IS NO RECALL. I WAS ABLE TO MANUALLY FEED THE BELT BACK INTO THE RETRACTOR, IT WAS EXTREMELY DIFFICULT BUT I SAT IN THE SEAT TO DUPLICATE THE ISSUE AND IT WILL DUPLICATE. THE SEATBELT IS CURRENTLY EXTENDED AND WILL NOT RETRACT AUTOMATICALLY. THE SHOULDER STAP WILL NOT FIT SECURELY AROUND A PASSENGER AT THIS TIME. I HAVE HAD NO PRIOR USE OF THE VEHICLE UNTIL TODAY AS I PURCHASED IT FROM A REPUTABLE DEALER WHO STATES THEY DID A FULL INSPECTION OF IT PRIOR TO SELLING BUT APPARENTLY THIS ISSUE WAS NOT REPAIRED PRIOR TO SELLING IT.

ENGINE FAILURE, 5/3/22, 23,987 MILES, ALL LIFTERS WAS REPLACED UNDER WARRANTY, ENGINE FAILURE, 7/6/26, 46004 MILES, TOOK TRUCK IN FOR OIL CHANGE AND WHEN RETURNED HAD A TICKING NOISE. DEALERSHIP NOTIFIED ME THAT CAMSHAFT ISSUES AND METAL DETECTED IN OIL. ENGINE NEEDS REPLACED. 6.2 V8 2018. TURPIN MOTORS, GENESEO, IL HAS DONE ALL SERIVCE ON TRUCK. NO WARNING LIGHTS OR CODES. VEHICLE IS IN MY GARAGE AND AVAILABLE FOR INSPECTION. I OPENED CASE WITH GM #105652237. DEALERSHIP OPENED CASE ON GM PORTAL ALSO. RESPONSE FROM GM IS THAT TRUCK IS OUT OF WARRANTY

Vehicle Details: 2018 GMC Sierra 1500 Z72 4x4, 5.3L V8 EcoTec3 engine, VIN: [XXX] Mileage at time of incident: 220,000 miles Location: [e.g., Little Rock, Arkansas area or specific road/highway – please provide if desired] What happened: The 5.3L V8 engine’s hydraulic roller lifters failed. One or more lifters collapsed, stuck, or lost proper oil pressure/operation. This led to improper valvetrain function, causing loud ticking/knocking noises, cylinder misfires, significant loss of engine power and performance, and internal engine damage (such as camshaft lobe wear or related components). Component or system that failed or malfunctioned: Hydraulic valve lifters (camshaft followers) in the engine valvetrain, associated with the Active Fuel Management (AFM) system. The failed lifter(s) and related components are available for inspection upon request. How safety was put at risk: The engine malfunction resulted in sudden or progressive power loss and misfiring while driving. This reduced the vehicle’s ability to accelerate or maintain speed, especially in traffic or on highways, creating a hazardous situation that put my safety and the safety of other road users at risk of collision or breakdown. No accident or injuries occurred , or other symptoms prior to the failure with details recall, e.g., ticking noise timeline, misfires Has the problem been reproduced or confirmed by a dealer or independent service center? “Yes, confirmed by shop inspection” Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? [Yes] Additional notes: Repair estimate is approximately $20,000 (likely due to extent of internal damage requiring major engine work or replacement). This failure aligns with a well-documented issue in GM 5.3L engines equipped with AFM. Vehicle status parked INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Power steering went out for 2-3 seconds as I was making a turn into a street , this happened twice to be exact

Incident description: On three occasion I have had the same catastrophic Engine failure putting myself and my family along with the general public in harms way. Starting March of 2022 while driving at approximately 60 MPH on the West Shore Expressway my truck experienced a sudden and total loss of motor power. My engine stalled out and I lost my ability to safety steer and stop my vehicle. This all happened during rush hour while driving in the left lane of traffic. This sudden loss of power forced me to maneuver the vehicle to the right shoulder of the expressway across the right lane of traffic. As there was no shoulder to pull over on the left side of the highway. This created an immediate crash risk for myself and other drivers. Upon inspection at the authorized GMC dealership where I purchased the truck new, a certified mechanic determined that the engine experienced a complete failure requiring replacement or rebuilding of the engine. I paid to have the engine rebuilt at the dealership. The second instance was similar to the above incident. Once again I paid for the repair. The third instance was more dangerous as when my trucks engine failed it almost caused an accident. As of today my truck is still sitting in the dealership for over 6 months and no one from the dealership or manufacturer will give me an answer on what has to be done now. This patter of sudden repeated engine failure clearly indicates a systemic safety defect that extends beyond normal wear and tear. I urge the NHTSA to open a defect investigation into the 2018 GMC Sierra 1500 engine systems.