By David Shepardson
WASHINGTON (Reuters) -The National Highway Traffic Safety Administration (NHTSA) said on Monday it was upgrading and expanding its investigation into 708,000 Ford Motor (NYSE:F) sport utility vehicles and trucks over catastrophic engine failures tied to a faulty valve.
The agency says under normal driving conditions vehicles without warning may experience a loss of power due to catastrophic engine failure related to a potentially faulty valve in 2.7 L and 3.0 L EcoBoost engines.
The investigation covers 2021 and 2022 model year Ford Bronco, Edge, Explorer, and F-150 and Lincoln Aviator and Nautilus vehicles.
NHTSA began a preliminary evaluation in July 2022 into 25,000 vehicles after opening a defect petition review in May following a request from some owners, and is now upgrading the probe to an engineering analysis, a required step before it could seek a recall.
A Ford spokeswoman said the automaker was working with NHTSA to support their investigation.
NHTSA said it had reports of 328 customer complaints and 487 warranty claims relating to the vehicles under investigation.
It said analysis of data submitted by Ford "revealed that the alleged defect is present across the 'Nano' engine family, which includes both the 2.7L and 3.0L EcoBoost engine variants."
Ford told NHTSA the defective valves were manufactured out of an alloy known as "Silchrome Lite" that can become "excessively hard and brittle if an over-temperature condition occurs during machining of the component."
Ford said a design change in October 2021 changed the intake valve material to a different alloy. Ford added it believed "defective intake valves commonly fail early in a vehicle’s life and has suggested that the majority of failures have already occurred."