In June 2022, the National Highway Traffic Safety Administration (NHTSA) started a detailed investigation concerning the Ford Bronco. The investigation, prompted by three petitions submitted in March of that year, focused on alleged valve defects found in select Bronco models. However, recent developments have taken this investigation to a more significant level as the NHTSA has now broadened its scrutiny to encompass not only the Ford Bronco but also over 700,000 Ford and Lincoln vehicles.
Initially, the organization initiated an inquiry into over 25,000 2021 Broncos equipped with the 2.7-liter EcoBoost engine following 26 complaints regarding a potential loss of motive power at highway speeds with no possibility of a restart. This loss of power was attributed to what the agency described as "catastrophic engine failures" stemming from the failure of engine valves.
Last week, NHTSA's Office of Defects Investigation elevated the investigation to an engineering analysis stage. This move followed Ford's provision of evidence comprising 328 customer complaints, 487 warranty claims, and 809 engine exchanges. These cases spanned 2021-22 Ford Bronco, Edge, Explorer, and F-150 vehicles, along with 2021-22 Lincoln Aviator and Nautilus models, all equipped with either 2.7-liter or 3.0-liter EcoBoost engines. It's noteworthy that, despite these concerning developments, there have been no reports of injuries, accidents, or fatalities associated with this issue.
"During the investigation, multiple contributing factors were identified, which can lead to the fracturing of the intake valves in the subject engines," NHTSA said in the document. "Ford acknowledged that a fractured intake valve can result in catastrophic engine failure and a loss of motive power and noted that following a valve fracture, a vehicle typically requires a full engine replacement." In return, a Ford spokesperson told Automotive News the automaker was “working with NHTSA to support their investigation.”
Gallery: 2021 Ford Bronco First Edition: Review
So far, the investigations have identified multiple contributing factors that can lead to the fracturing of the intake valves in the affected engines. An integral part of the issue is the material used for the defective intake valves, which is known as Silochrome Lite. Ford explained that this alloy can become "excessively hard and brittle if an over-temperature condition occurs during machining of the component." The automaker initiated a design modification in October 2021, switching to an alloy less susceptible to overheating for the intake valves.
While vastly different as a vehicle, the Mustang Mach-E was recently investigated for a similar problem. The electric crossover had potentially defective contactors on the high-voltage battery that could overheat after DC fast charging. This, in turn, could lead to a loss of power.