The black circular object in your picture is the vent for the cylinder head sometimes called a PCV Valve. It vents oily engine vapors into the engine through the intake so they can be burned. Sometimes the vent valves get gummed up internally and don't work as they should. The circular rubber gasket where the valve fits into the head is also a source of vacuum leaks if it not replaced from time to time. They cost around $60 new so I flush them out to get rid of the accumulated sludge. FR








