05 Civic Ex, 185k miles, slightly leaky head gasket. Eats oil for breakfast and last oil change was down significantly. Only developed this tapping noise the last week after the oil change. Runs fine, smooth up the the rpm range. Used a stethoscope all over and cannot pinpoint the location but sound like it coming from under the airbox 🤷‍♂️. Strange I know. Any suggestions would be greatly appreciated.