THERMACTOR Air (Reed) Check Valve (THERMACTOR II Only)
When pressure in the exhaust manifold is more than the pressure in the air cleaner (positive pressure), the air inlet valve closes. When pressure is less in the exhaust manifold than in the air cleaner (negative pressure), the valve opens. At this point, air is drawn into the exhaust manifold where it reduces hydrocarbon and carbon monoxide emissions by continuing the combustion of unburned gases in the same manner as an air pump system. This opening and closing is a normal pattern established by exhaust gas pulses created by the combustion process.
NOTE:
Although the Thermactor Air Check Valve may look like the Exhaust Check Valve, the two are NOT interchangeable.