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JDA1192 PT 64 0001 Preventing Premature Failure of Pulley driven Vacuum Pumps All pulley driven vacuum pumps Premature vacuum pump failure Incorrect belt tension bent pulleys collapsed or deteriorated vacuum hoses brake fluid entering the unit or wrong unit Follow the checklist below to prevent pump failure Verify pump is correct for the application Different shaft sizes are used because of different pump rotation DO NOTmodify the pulley to force installation If the pump is operated in the wrong direction it will fail Do not over tighten pulley belt Make sure an automatic tensioner is working correctly Be sure the belt is properly aligned with the pulley or tensioner ALWAYSinstall the pulley using the supplied installation kit or appropriate tool DO NOTuse a press or hammer to install pulley A faulty master cylinder or booster seal can allow brake fluid to enter the vacuum pump If brake fluid enters the system it will be necessary to replace all three parts Do not allow radiator or power steering hoses to contact the pump Excess heat transferred from the hoses will destroy the vacuum pump Check inlet hose for collapsing A blocked or collapsed hose will cause bearing failure When replacing vacuum hoses use only vehicle manufacturer specified hoses DO NOT LUBRICATE THE UNIT CARDONE units are assembled using a specific type and amount of lubricating oil Adding oil through the hose will damage the diaphragm and cause the unit to fail prematurely Be sure the area around the vacuum pump is clear of debris Verify the repair by checking the available vacuum before and after vacuum pump replacement Use a vacuum gauge to measure pump vacuum level minimum 18 inches of mercury See reverse side for vacuum pump testing tip Cause Problem Solution Application Be sure to measure vacuum properly If a customer s vehicle is exhibiting the following symptoms you may need to replace the vacuum pump Brake pedal is firm or hard booster Check engine light is on control valve Lack of power poor acceleration or a rough idle advance timing No control over heat or A C defaults to defrost mode HVAC Inoperative cruise control Proper measurement of vacuum is critical in determining whether a pump has failed Placing a thumb over the hose opening to test suction is NOTsufficient You must use a vacuum gauge to measure it properly If the measurement comes to anything less than 18 Hg then you have a faulty vacuum pump 0 525 30 10 15 20 INCORRECT METHOD CORRECT METHOD 18 Hg minimum
