These seemingly innocuous parts are a recipe for total engine failure.
A good example of how precise the process of building a car needs to be is Hyundai and Kia's latest spate of engine issues, which comes to our desks via Detroit News. Not only must a car be designed, mass-produced, and operate well in the hands of a customer, but it must also must go as long as possible without breaking down. It's a given that no car will last forever, but when road-going Hyundais and Kias began dropping like flies, the Korean automakers decided to investigate.
According to documents submitted to the NHTSA by Kia, the problem that owners are encountering stems from leftover metal debris that remain in the engine after the production process. Additionally, the machining process of the crankpins could have been completed incorrectly resulting in uneven surface roughness. These small particles and the rough surface can then restrict oil flow to the connecting rod bearings. Given that the oil helps cool these parts, the components can overheat when deprived and cause wear on the connecting rod bearing. Once it gets bad, a knocking sound will begin to emit from the engine and could result in warning lights on the dashboard or a complete stall.
The issue affects a staggering 1.2 million vehicles in the U.S., Canada, and South Korea including US versions of the 2013-2014 Hyundai Santa Fe and Sonata, 2011-2014 Kia Optima, 2011-2013 Kia Sportage and 2011-2014 Kia Sorento. Affected models have the 2.0-liter or 2.4-liter gasoline engines with the U.S. market engines built at Hyundai's engine plant in Alabama. No crashes have been reported, but given that a stalling engine poses grave dangers at high speeds, Hyundai and Kia are announcing the recall. Unfortunately for the two automakers, these problems aren't anything new. In 2015, Hyundai recalled nearly half a million 2011-2012 Sonatas with the same engines for the same issue.
At first, Kia and Hyundai did not think the problem was affecting customer cars in large numbers because warranty claims were low, but after the reports began to flood in, the automaker issued extended engine warranties and later began recalling motors in 2016.