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 1:37 pm #942667 Richard KirshyParticipant No matter what the cause.. You’ll need to remove the valve cover in order to determine the cause. Once you see the root cause then come back and do your inquries.