Engine bay close-up of an alternator and serpentine belt over a…

130A alternator from V6 Taurus (8 1/8" between the mounting bolts, & case clocked for this application) in the factory bracket on my '95 4.9L engine. This 3G alternator is easily identifiable as a 130A model by the 2 vent holes between each pair of front ribs (at about 10:00 position). 95A models have 4 holes.

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To test the alt, first install a good CHARGED battery and connect a voltmeter across the battery posts (NOT the clamps AROUND the posts). With the engine at 1500-2500RPM, momentarily ground the screw on the back of the alt where it says GROUND HERE TO TEST (the Field brush screw) using a jumper wire. The voltage should instantly spike over 15.5V, and continue to climb slowly. Don't ground that screw for any longer than it takes to make this observation (a couple of seconds). If it fails, the fault could be in the alternator, the wiring, or any connection (including the alt to the block).

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Be sure to clean the mounting points & battery terminals:

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Various applications will have the rear case clocked differently, so if your wiring doesn't reach, FIRST loosen the front nut and take the pulley off. Then remove the 3 case bolts, flip it, lift the front case while pushing the shaft into the case slightly, rotate the front, set it down, and reassemble it. If the shaft (armature) slides out of the rear case, the brushes will shoot out behind the commutator. Simply remove the voltage regulator, push the brushes back in, pin them with a paperclip or toothpick, finish assembling the alternator, reinstall the VR, and remove the pin.

Owner caption September 2004 · Photo 662 of 5000