To be certain, you'll need to consult a repair manual specific to your 1988 Chevy Celebrity 2.8L engine. A Haynes or Chilton manual would be very helpful for this. You can also find diagrams online by searching for "1988 Chevy Celebrity 2.8L engine diagram" and looking for images showing the valve cover. Look carefully at the valve cover for a small, capped valve with a hose.