IMPORTANT: Place vehicle in neutral and disconnect batteries before working on the electrical system. DO NOT TEST THE ALTERNATOR BY DISCONNECTING THE BATTERY LEAD TO SEE IF IT SPARKS. THIS WILL DAMAGE THE ALTERNATOR AND MAY VOID THE WARRANTY.
Test Batteries Before Alternator Installation:
Before installing your alternator, make sure the battery is in good condition, fully charged and has the proper capacity. A defective battery can cause an alternator to prematurely fail, while a discharged battery can significantly shorten your alternator’s lifespan. Keep in mind the purpose of an alternator is to maintain your battery’s charge, not recharge the battery.
Inspect All Wire and Battery Cables:
Check that your battery cables, alternator wiring and wiring connections are tight, in good condition and completely free of corrosion. Alternators can be damaged by added resistance to the charging system caused by loose connections and corrosion. If you’re upgrading the vehicle to a higher amperage alternator, it’s crucial that the wiring in the charging circuit can handle the additional output.
Inspect the Fan and Pulley:
An alternator’s life can be shortened by a damaged fan. Similarly, a damaged pulley can affect drive belts and cause them to slip and drive the alternator at improper speeds. Another issue to avoid is the fan and pulley being out of balance, causing vibration and the eventual early breakdown of the alternator.
Properly Torque the Fan and Pulley in Place:
If the rotor doesn’t spin freely once the alternator has been removed, don’t throw it out! When you install the fan and pulley, torque the pulley nut to 70-80 ft. lbs. This will locate the rotor properly in the alternator and cause it freely turn.
Use Proper Mounting Hardware:
When mounting the alternator use grade 5 bolts and self-locking nuts. It’s also recommended to use hardened flat washers under the bolts and lock nuts. If you’re using a slotted-type adjusting bracket, remember to place a hardened flat washer between the adjusting ear and avoid using lock washers.
If Alternator Fails After Proper Installation:
Increase Engine Speed:
The alternator must get up to sufficient speed before the regulator turns on and energizes the field circuit. This may be higher than “idle” speed. If this condition happens, increase engine speed until the regulator turns on. Once the regulator turns on it will remain on until the engine is stopped.
Magnetize the Rotor:
Magnetism is usually kept by the rotor to provide sufficient voltage build-up to turn on the field circuit when the engine is started. However, if a unit has been in inventory, disassembled or serviced, it may need to have its magnetism re-established. This is done by magnetizing the rotor, which you can accomplish by connecting the alternator to the electrical system in the normal manner. With the engine off momentarily, connect a jumper lead from the battery positive to the relay terminal of the alternator. (The relay terminal is the small pin type terminal generally covered by a rubber cap.) This applies to both positive and negative ground systems. This will restore the magnetism in the rotor and the alternator will begin operating correctly.
Test Alternator Operation:
Alternator output should be 20% over total system requirements. The regulator has been preset to O.E. specifications. Vehicle indicator gauges may not reveal accurate charging system operation. Reliable test equipment should be used when testing or troubleshooting the electrical system.