Chevrolet reveals cause behind flurry of IndyCar engine changes in Detroit

At least seven Chevrolet teams have changed engines ahead of IndyCar's Detroit GP

During IndyCar warm-up on Sunday in Detroit, Chevrolet General Motors president Mark Reuss confirmed the root cause of the issue behind a rash of engine changes in the IndyCar garage.

"We had a supplier issue with the valve and the valve guide, and it's a coating issue," Reuss told IndyCar on FOX. "And so if you can imagine the valve sitting in the guide with the wrong coating, over time, you get to see the valve chuck off the seat. And so, it becomes fatigued. It doesn't happen on every engine, but we had a lot that didn't have the coating, so what we're doing is we're going in and changing those coatings and valves to make sure we run as reliable as we have since 2012.

The Chevrolet cars of Josef Newgarden, Pato O'Ward, Nolan Siegel, Christian Lundgaard and David Malukas all underwent engine changes Saturday night after qualifying. Before qualifying, there were also engine changes for Lundgaard (again), and also Rinus VeeKay and Sting Ray Robb.

Chevrolet, which was one of the driving forces behind the move from Belle Isle to downtown Detroit, is still searching for its first win in the Detroit GP as the event enters its fourth year.

Team Penske driver Scott McLaughlin qualified best among the bowties, as he will start third behind Ganassi's Alex Palou and Andretti's Will Power.