Darlington Raceway is known for being notoriously harsh on stock cars. This year’s Cook Out Southern 500 was no different. Notably, Kyle Busch and Martin Truex Jr. retired from the race while contending for the win after both of their Joe Gibbs Racing Toyotas suffered engine failures. The most startling retirement of the night was when the No. 4 Stewart-Haas Racing Ford Mustang burst into flames. Kevin Harvick escaped the car unharmed, but the blaze was the latest in a series of connected fires.
Forty-five laps into the Southern 500’s final stage, the broadcast feed cut from an ongoing cycle of pit stops to Kevin Harvick coming to a stop on the Turn 1 apron. The cockpit of the Mustang was filling with smoke as flames spread from behind the right-front wheel across to the opposite side. In the garage area, Harvick vented his frustrations and told NBC, “I’m sure it’s just the crappy parts on the race car, like we’ve seen so many times. We haven’t fixed anything. It’s kinda like the safety stuff, we just let it keep going and keep going. The car started burning, and as it burned the flames started coming through the dash.”
The source of Harvick’s fire was immediately traced to the rocker box assembly on the floor on the NextGen car behind the right-front wheel. As outlined by Bozi Tatarevic on Twitter, fine rubber can find its way into the rocker box through front grille inlets and ignite. The inlets as well as a set of hoses and fans were part of a fix to help keep the cockpit reasonably cool for drivers. Harvick’s fire is the fourth since the Verizon 200 at the Brickyard at the end of July. NASCAR is working on finding a solution and Kevin Harvick now finds himself as the bottom of the playoff standings after the first race.