Air Guard System: Operation: Notes

Fresh air is drawn into the air pump through a filter fan. The air is compressed in the pump and then discharged through the pump to the diverter valve. The diverter valve directs air to the air distribution system or dumps it through a by-pass port, depending on engine operating conditions. Air pressure in this system is maintained at approximately 5 psi (7.5 psi in California) by a relief valve incorporated in the diverter valve.

The air mixes with hot exhaust gases and causes a further burning of the mixture, reducing hydrocarbon and carbon monoxide emissions.

On 4-cylinder engines, air flows from the diverter valve through a check valve attached to a fitting in the intake manifold adjacent to number 3 cylinder. A distribution passage in the cylinder head carries air to drilled holes intersecting the exhaust valve ports.

On all other engines, air from the diverter valve is directed into the air injection manifold(s). At each exhaust port, a hollow screw carries air into the exhaust manifold(s).

California 6-cylinder engines are equipped with a vacuum delay valve. This valve, installed between the manifold vacuum source and the diverter valve, reduces the diverter dump mode operating time.