ALTERNATOROVERHAUL
AUTOMOTIVE TECHNOLOGY
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BEFORE YOU REMOVE ALTERNATOR
• Pay attention to how wires are connected
• Pay attention to Alternator oreintation
• Disconnect Battery!!• Check Belt tension and
condition• Check wiring condition
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DISASSEMBLY
• Mark frames for correct reassembly• Note spacers placement• Identify Alternator by Part Number• Note Terminal Condition & orientation
Partnumber
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INSPECTION OF “COM” END HOUSING
• Bearing condition
• Stator windings• Pulley condition• Brush wear• Internal Wiring
Connections• Component
external damage
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INSPECTION OF DRIVE END HOUSING (FRAME)
• Bearing race housings• Frame Condition
– Cracks
– Wear
– Stripped threads
• Mounting boss condition
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• Rotor slip ring condition
• Rotor Windings external condition
• Shaft condition• Cooling Fan
condition
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TESTING ROTOR FIELD COIL
• Rotor resistance– GM 2.4 to 3.5 ohms
– Ford 3.0 to 5.5 ohms
– Chrysler 3.0 to 6.0 ohms
• Some shop manuals give rotor specifications in amps.
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ROTOR TESTING FOR GROUNDED SLIP RINGS
• Inspect rotor lead soldering area
• Test rotor for Grounds to shaft
• Can use ohmmeter
• Can use 110 Volt continuity tester
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ROTOR TESTING FOR ROTOR TESTING FOR GROUND TO ROTOR GROUND TO ROTOR
FRAMEFRAME• Test rotor for
grounds to rotor frame (open circuit cats claw)
• Should be • Inspect cats claw
for signs of rubbing on stator
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DIODE TESTING• Check Positive diodes
for one way operation by switching leads.
• Can test with diode check function of DVOM
• Can check with 110V diode tester tool.
• Check Negative Diodes also
• Must only get continuity one way!!!
Note: Diodes can be checked on car with Sun VAT 40
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TEST STATOR FOR CONTINUITY
• Check Stator for Continuity between phases of windings
• Usually check resistance of windings
• Must be same resistance
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TEST STATOR FOR GROUNDS• Make sure Stator
windings are not grounded to frame!
• Inspect windings for worn spots on windings.
• Check looseness
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DELCO REMY 25SI AND 30SI ALTERNATORS
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ADVANTAGES OF HEAVY DUTY 25-SI ALTERNATOR
• BRUSHLESS - ROTOR WORKS ON PERMANENT MAGNETISM
• BELT OR GEAR DRIVEN
• 12V, 24V, 32V
• 85 AMP TO 300 AMP CAPABILITY
• ELECTRONIC REGULATOR
• 12V - 24V COMBINATION OUTPUT
• SOME ARE OIL COOLED
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LOTS OF WIRE CONNECTIONS!!!
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25SI ROTOR• Rotor doesn’t spin in
this alternator• Stator is stationary
also• Inspect Rotor and
stator for interference• Check stator and rotor
as any other alternator
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25SI ROTOR HOUSING• Inspect for interference• Inspect bearing races• Remove bearing race
with bearing splitter• Inspect D.E. Bearing• Inspect C.E. Bearing• Inspect Housing
threads and condition
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REPAIR• Clean components
– OK to clean in solvent but make sure dry
• Replace Bearings– Don’t spin bearings– Inspect races closely– Use proper procedures to replace and remove
bearings.
• Replace Brushes and Springs
• Replace other faulty components
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REASSEMBLY
• Proper Torque
• Paint Housing if necessary
• Use Lock Tight on H.D. Alternators
• Make sure there is no tension on wiring
• Make sure connections are tight!!
• Always retest output after Overhaul.
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Final Bench Testing
• Check amperage output– Look up specifications In book– Listen for abnormal noises
• Check internal regulator operation– Make sure cutoff voltage is correct.
• Test Light/Indicator circuits also.
• Reinstall on Vehicle