A federal judge has handed General Motors a key procedural victory in the long-running GM lifter lawsuit, denying a late-stage effort by plaintiffs to split the case into two separate legal battles.
The ruling keeps the consolidated litigation intact in the U.S. District Court for the Eastern District of Michigan, where it has been pending since December 2021. The case will continue to cover vehicles equipped with both Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) systems under one unified proceeding according to a Carcomplaints.com report.
Lawsuit Targets AFM and DFM V8 Engines
The lawsuit centers on alleged defects in lifters and valvetrain components used in certain GM full-size trucks and SUVs. Plaintiffs claim the 5.3-liter L84 and 6.2-liter L87 V8 engines can experience premature lifter failures that lead to misfires, ticking noises, rough operation and, in some cases, stalling.
Vehicles named in the litigation include the Chevrolet Silverado 1500, GMC Sierra 1500, and Cadillac Escalade, among others.
According to the complaint, the alleged failures stem from lightweight lifters that were improperly positioned within the engine. Plaintiffs further argue that replacement parts carry the same design flaws, meaning repairs may not permanently resolve the issue.
The engines in question utilize cylinder deactivation technology — AFM in earlier applications and DFM in newer models — designed to improve fuel economy by shutting down select cylinders under light load conditions.
Four Years of Legal Wrangling
The case has seen extensive procedural activity over the past four years. Some plaintiffs withdrew from the action, attorneys exited the case, and 17 claims were temporarily sent to arbitration before returning to federal court.
Most recently, plaintiffs sought to sever the case into two distinct actions. Their legal team argued they had identified a “significant distinction” between AFM and DFM engines, claiming the alleged defects differ enough to justify separate trials and independent class certification efforts.
General Motors strongly opposed the motion.
The automaker argued that dividing the case at this stage would require duplicative expert discovery, additional class certification briefing, repeated summary judgment motions and potentially two full trials. GM characterized the proposal as inefficient and unnecessarily burdensome for both the court and the parties involved.
Judge Criticizes Timing of Severance Request
U.S. District Judge Laurie J. Michelson sided with GM, denying the motion and questioning the timing of the plaintiffs’ request.
In her written opinion, Judge Michelson noted that concerns about differing failure mechanisms were not new. She referenced a January 2023 ruling in which the court observed that while plaintiffs alleged a single uniform defect, their claims appeared to describe “three separate part failures.”
She also reminded the parties that she had previously signaled the possibility of severance discussions based on specific engine components.
“So while the Court is not surprised to see that a party seeks severance of claims here,” Michelson wrote, “it is surprised at the timing of this request: four years after the suit was filed and almost three years since the Court issued that warning.”
The decision suggests the court was unwilling to significantly restructure the litigation at such a late stage.
What the Ruling Means Going Forward
For GM, the ruling avoids immediate duplication of legal work and keeps the case consolidated under a single procedural framework. Maintaining one lawsuit reduces the complexity and cost associated with running parallel discovery tracks and separate trials.
For plaintiffs, the denial represents another setback in a case that has already faced multiple delays.
Discovery will now continue simultaneously across claims involving both AFM and DFM systems. The engines — and the lifter design at the center of the dispute — remain under scrutiny as the litigation moves toward potential class certification and future dispositive motions.
While the ruling does not address the merits of the defect claims themselves, it clarifies that any resolution will proceed within one broad, unified case rather than two smaller ones.
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