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Aftermarket Alternator Insulator 42-82312
The Aftermarket Alternator Insulator 42-82312 is a new replacement insulation component designed for specified Nippondenso 50A ER/EF alternators. Measuring 6 mm inside diameter and 20 mm overall length, it provides proper electrical isolation for the alternator output terminal while maintaining correct terminal alignment during alternator rebuilding and repair.
Product Specifications
Product Type: Alternator Insulator
Condition: New Aftermarket Replacement
Fits: Specified Nippondenso 50A ER/EF Alternators
Dimensions: 6 mm ID × 20 mm Overall Length
Cross References
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WAI: 42-82312
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ACE/Accurate: S-4539
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OEM: 021605-1320
Compatible Lester Numbers
12080, 12081, 12179, 12180, 12182, 12187, 12188, 12190, 12197, 12204, 12270, 13217, 13234, 13338, 13503, 13555, 13601, 13740, 14732, 14739, 14872, 14926, and 14927.
Features & Benefits
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Precision aftermarket replacement
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Maintains proper electrical isolation of the charging terminal
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Supports correct output terminal alignment
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Manufactured to match original dimensions
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Ideal for alternator rebuilding and repair
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Cross-referenced to OEM and aftermarket part numbers
What Does an Alternator Insulator Do?
The alternator insulator electrically separates the charging terminal from the alternator housing, preventing unintended electrical contact while supporting the output stud and insulating hardware. Proper insulation is essential for safe and reliable charging system operation.
Years of engine heat, vibration, moisture, and repeated tightening of terminal hardware can cause the original insulator to become brittle, cracked, or damaged. Replacing worn insulation during a rebuild helps restore proper electrical isolation and long-term charging system reliability.
Common Signs Replacement Is Needed
Replace the alternator insulator if you notice:
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Cracked or broken insulation
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Heat damage or discoloration
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Loose or unsupported output terminal hardware
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Missing insulating sleeve
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Electrical arcing around the charging terminal
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Damage discovered during alternator rebuilding
Compatibility & Fitment
Always compare the original component before ordering. Verify the part number, dimensions, shoulder profile, and installation orientation using the OEM, WAI, ACE/Accurate, and Lester references whenever possible.
Vehicle year, make, and model alone may not identify the correct internal alternator component, as manufacturers often used multiple alternator designs during the same production year.
Installation Recommendations
Installation should be performed by a qualified technician or experienced alternator rebuilder. Install the replacement insulator in the same orientation as the original component without trimming or modifying the part. After reassembly, verify that the charging terminal remains electrically isolated from the alternator housing and bench-test the alternator whenever possible.
While You're Rebuilding
Inspect other common wear components to help maximize charging system reliability:
Why Buy From RC Auto Electric?
RC Auto Electric specializes in alternator and starter rebuilding components for professional rebuilders, repair shops, automotive technicians, and DIY enthusiasts. Our extensive catalog includes thousands of OEM and aftermarket electrical components backed by accurate cross-reference information to help simplify part identification and reduce ordering mistakes.
Disclaimer
Compatibility information is provided as a reference only. Manufacturing revisions, production changes, and previous rebuilding modifications may affect internal alternator components. Always compare the original part, dimensions, cross-reference numbers, and product photographs before installation. If you are unsure about compatibility, contact RC Auto Electric before ordering.
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Frequently Asked Questions
How do I verify that this is the correct alternator insulator? +
Always compare the OEM number, WAI number, ACE/Accurate number, Lester number, dimensions, and the physical design of your original part before ordering. Because manufacturers often used multiple alternator configurations within the same model year, vehicle year, make, and model alone may not identify the correct internal component.
Why should the alternator insulator be replaced during a rebuild? +
Alternator insulators are exposed to years of engine heat, vibration, moisture, and mechanical stress. Replacing the insulator during a rebuild helps restore proper electrical isolation, reduces the risk of electrical shorts, and improves the long-term reliability of the charging system.
What problems can a worn or damaged alternator insulator cause? +
A damaged insulator can allow the alternator output terminal to contact the alternator housing, potentially causing electrical shorts, intermittent charging issues, blown fuses, or charging system failure. Replacing worn insulation is a simple way to help prevent future electrical problems.
What is a Lester number, and why is it important? +
Lester numbers are the industry standard for identifying alternators and starters across multiple manufacturers. Professional rebuilders and parts suppliers use Lester numbers to help identify compatible internal components. For the most accurate fitment, always compare Lester numbers together with OEM numbers, dimensions, and product photos.
What other components should I inspect while rebuilding my alternator? +
With the alternator already disassembled, inspect other common wear components including the bearings, brushes, brush holder, slip rings, voltage regulator, rectifier, capacitor, rotor, and stator. Replacing worn components during the same rebuild can improve charging system reliability and help reduce future labor.