Air Injection Pump: Description and Operation

The air pump consists principally of the pump body, cover, rotor, vanes and press-fitted relief valve. The pump is belt-driven by the pulley mounted on the water pump shaft of the engine.

Air is drawn through the air cleaner and suction hose into the pump suction chamber, where it is trapped between two vanes and pump body. As the rotor turns, these vanes carry the air to the outlet chamber and then to the air manifold.

The relief valve, press-fitted into position on the outlet chamber, is held closed under normal operating conditions by means of the spring. However, when the pressure of air at the outlet overcomes the tension of the spring, the valve is pushed open and releases excess air so as not to exceed the outlet air pressure of the pump.