The Actual Cause Behind the Recall of Millions of Engines This Year | Carscoops

      Automakers are grappling with escalating warranty expenses as high-performance engines fail due to minute defects.

      Modern engines require nearly flawless machining along with thin layers of oil.

      Over 5 million engines from various manufacturers are facing recalls or investigations.

      The growing warranty costs and extensive engine replacements are straining repair shops and consumer trust.

      Some recalls are minor, while others significantly impact financial reports. This year, several have fallen into the latter category, primarily involving engines.

      In April, GM recalled 721,000 6.2-liter V8 engines, while Toyota followed with over 102,000 V6 engines in 2024. Honda recalled nearly 250,000 V6 engines, and Stellantis is addressing issues with 112,589 turbocharged four-cylinder engines flagged for defects.

      Currently, more than five million engines from five different manufacturers are either recalled or under federal investigation in the U.S., creating a costly dilemma that’s easier to trigger than to resolve, particularly when brand reputation is at stake.

      What’s Behind the Problems?

      These instances, among others, are linked to a common issue highlighted by Automotive News: lightweight oil and extremely narrow tolerances.

      Automakers have spent decades reducing engine displacement since smaller engines typically consume less fuel. To further enhance this advantage, they have focused on improving thermal efficiency wherever feasible.

      Additionally, finding ways to satisfy consumers' desires for power has become necessary. Modern engines often integrate these elements to optimize both power and efficiency.

      To operate effectively, these engines rely on low-weight, ultra-thin motor oils such as 0W-16 or 0W-20. These oils minimize drag and friction while aiding manufacturers in achieving fuel economy goals.

      They are crucial as they function well within the ultra-tight lubrication margins of modern engines. These tight tolerances are a significant factor contributing to the current recalls.

      Previously, larger tolerances in engines could accommodate tiny machining errors during production. Today, modern engines are not as forgiving. If any machining debris contaminates the crankcase or head, it can lead to catastrophic failures swiftly.

      Examining the recalls mentioned reveals a common thread.

      How Manufacturing Debris Becomes an Issue

      GM’s recall of its reliable LS V8 engine identified failures related to bearing wear, crank defects, and metal swarf (a machining byproduct) in the lubrication pathways. Replacing a single engine can take around 18 hours, so it’s unsurprising that GM is allocating over $1 billion to address the issue for customers.

      Toyota’s V35A twin-turbo V6, used in the Tundra pickup, faced a similar issue. Minor metal debris from machining infiltrated the crankcase of some engines, prompting Toyota to add another 127,000 affected engines to the initial 102,000 last month.

      Honda’s recall pertains to engine bearings and connecting rods, while Stellantis acknowledged that some recalled engines could contain sand, another production byproduct.

      Automotive News indicates that these failures, among others, have led to more than $8 billion in losses across the involved brands. Hyundai accounts for the majority of this, with around $5 billion likely dedicated to the recall of 3.3 million engines reportedly containing metal debris, faulty rod bolts, and improperly installed piston rings.

      Modern engines undoubtedly represent a significant engineering achievement. When manufactured correctly, they deliver greater power, increased efficiency, and improved overall performance compared to older models. However, ensuring their correct assembly remains a challenge, even for top-tier automakers.