One of the 150 utility covers that were welded shut ahead of NASCAR's weekend at Naval Base Coronado came loose on lap one of the O'Reilly Auto Parts race and flew straight into Day's radiator.On the opening lap of NASCAR's O'Reilly Auto Parts Series United Rentals Driven to Serve 250, Corey Day was the unlucky driver to hit a utility cover after it shook loose following two days of race activity on the active Naval Base Coronado. "We have a manhole cover sitting in our radiator," Adam Wall radioed to Day.The utility cover, which appears to be about half the size of a traditional manhole cover, was knocked loose and somehow flew perfectly into the center of Corey Day's grill, punching through the radiator. The day was starting at the back of the field in a backup car after hitting the wall in qualifying on Friday afternoon. The No. 17 Hendrick Motorsports team is allowed to change the radiator in the open work area. NASCAR has made the exception to its rule, "the same radiator must be used at all times during an Event", because the problem was caused by the track, as reported by Fox Sports' Bob Pockrass on X. After running five laps under caution, NASCAR was forced to red flag the race so the utility cover could be re-welded onto it's hole. Day's team is allowed to continue working while the race is red-flagged.Under the red flag, NASCAR has sent officials around the full 3.4-mile temporary street circuit to check for more loose manholes.Mike Ford, Vice President of Racing Communications, posted on X that during the red flag track check, one more loose utility cover was found and rewelded, this one in turn six. The No. 17 team was able to complete repairs before the end of the red flag. NASCAR initially credited Day with one lap completed, meaning he would rejoin the race four laps down once the red flag was lifted and the race resumed.NASCAR reversed their decision to give Day one lap, and let him run four laps alone under caution to catch up, but have the same tire wear as the field.