The suction air system is used on some models with the 200 cic (3.3L) engine. It consists of a hose which runs from the clean side of the air cleaner to the exhaust manifold. Mounted midway in the hose is a silencer and an air inlet valve. The air inlet valve acts like a check valve.
Suction in the exhaust manifold pulls air from the air cleaner. This air oxidizes the hydrocarbons and carbon monoxides. The inlet valve prevents backflow of the exhaust into the air cleaner.
Because there is pulsating in the exhaust, it is normal for the air inlet valve to vibrate, especially at idle. The silencer prevents these vibrations from reaching the air cleaner.
To check the system, remove the silencer and check the air inlet valve to be sure it is vibrating at idle. There should not be any backflow of exhaust out of the valve.