Air Pump Noise

To check air pump, proceed as follows:

1. Check drive belt tension. If belt needs tightening, do not pry on housing. Excess belt tension will result in damage to pump.
2. If noise is still present, remove belt and turn pump to check if it is binding or seized. Pump may be noisy when rotating by hand. If rotation is satisfactory, reinstall belt.
3. Make sure all hoses are connected and have not vibrated free. Check that hoses are not touching other parts of vehicle. With pump running, check entire system for leaks in hoses and around clamps. Check may be made with soapy water.
4. Make sure pump mounting bracket is fastened securely. Check relief valve. If air escapes from valve during idle, failure has occurred and pump must be replaced. Absence of pressure setting plug in relief valve will result in premature pressure relief and excessive noise.
5. Bearing noise is easily distinguished from vane chirping. Vane chirping is intermittent and noticeable at low speed. Bearing noise is noticeable at all speeds. Sound does not necessarily indicate bearing failure, if bearing noise increases to objectionable level, pump should be replaced.
6. Failure of a rear bearing is identified by a heavy knocking noise. Since bearing is not serviceable, pump must be replaced.