A number of Sprint Cup teams, including all four cars from Hendrick Motorsports, have been forced to change their engines in the build-up to the Gatorade duels, which will set the starting order for Sunday's Daytona 500.
The first sign of alert for Hendrick came during Wednesday's second practice session when Bud Shootout winner Dale Earnhardt Jr lost his engine. After that, and having reviewed the situation, the team found a problem with the coating of the lifters.
According to Hendrick Motorsports Head Engine Builder Jeff Andrews, the issue is related to a batch of lifters, but he claims to be confident on the reliability of the overall package ahead of the Gatorade Duels and the Daytona 500.
"We have, I think, three durability runs on our AVL dynos back at the shop so we have a lot of confidence in the package," Andrews said. "The same package we raced in the Bud Shootout.
"We took engines back after the Bud Shootout, they look really good. Looked, great, so we are looking at a batch issue right now and trying to sort through some things to get the guys in Charlotte pointed in the right direction."
Other cars running Hendrick engines, like Joe Nemechek's Furniture row Impala, were reportedly warned about the issue but have not changed their units, apparently because the lifters are not from the same batch used on the four Hendrick cars.
Some Toyota teams have also been hit by a similar issue, leading to further engine changes, including Team Red Bull's AJ Allmendinger, Joe Gibbs Racing's Tony Stewart and Denny Hamlin, plus JJ Yeley, who runs JGR engines for Hall of Fame Racing.
As a consequence of the engine changes, Jimmie Johnson will start from the back of the grid on the first Gatorade Duel, although he will not lose his Daytona 500 pole position as all drivers are entitled to an engine change following Thursday.
All other drivers changing engines will also go to the back of the field for the start of their respective Duels.
Subscribe to Autosport Plus
Register for free