ALTERNATOROVERHAUL

AUTOMOTIVE TECHNOLOGY

JH

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

JH

DISASSEMBLY

• Mark frames for correct reassembly• Note spacers placement• Identify Alternator by Part Number• Note Terminal Condition & orientation

Partnumber

JH

INSPECTION OF “COM” END HOUSING

• Bearing condition

• Stator windings• Pulley condition• Brush wear• Internal Wiring

Connections• Component

external damage

JH

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

JH

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.

JH

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

JH

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

JH

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

JH

TEST STATOR FOR CONTINUITY

• Check Stator for Continuity between phases of windings

• Usually check resistance of windings

• Must be same resistance

JH

TEST STATOR FOR GROUNDS• Make sure Stator

windings are not grounded to frame!

• Inspect windings for worn spots on windings.

• Check looseness

JH

DELCO REMY 25SI AND 30SI ALTERNATORS

JH

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

JH

LOTS OF WIRE CONNECTIONS!!!

JH

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

JH

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

JH

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

JH

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.

JH

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