Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Sudden loud knocking / tapping directly under valve cover… please help › Reply To: Sudden loud knocking / tapping directly under valve cover… please help March 5, 2020 at 5:19 pm #942673 Richard KirshyParticipant If it were a timing issue, chances are the engine would be running pretty rough.