Choosing the Right Alternator for Your 1981-1986 Chevrolet Impala
Keep your classic Impala's lights bright and battery charged by choosing the right replacement alternator.
- Symptoms often start with dimming lights, whining noises, or a battery light on the dash.
- For a GM vehicle of this era, ACDelco is a trusted aftermarket choice for OEM-grade quality.
- Confirm the amperage and 'clock position' of your old alternator before buying a new one to ensure proper fit and function.
- If you have added electronics, consider upgrading to a higher-output alternator from a brand like Powermaster.
Is Your Impala's Alternator Failing?
The electrical system on the 1981-1986 Impala is simple, which makes spotting alternator trouble straightforward. If the alternator starts to fail, it can't produce enough power, and your car will try to run off the battery alone, which won't last long. Watch for these clear warning signs:
- Dim or Flickering Lights: Headlights and dash lights that pulse, get dim at idle, or flicker are a classic sign of a weak alternator.
- 'GEN' or Battery Light: The battery-shaped warning light on your dashboard is your car's way of telling you the charging system has a problem.
- A Whining or Grinding Noise: A high-pitched whine or a low growl from the front of the engine that changes pitch as you rev the engine often means the bearings inside the alternator are worn out.
- Weak or Dead Battery: If you find yourself needing to jump-start your Impala frequently, a bad alternator is a likely culprit because it's not recharging the battery as you drive.
- Slow Electrical Accessories: Power windows that seem sluggish or a radio that cuts out can be caused by the low voltage from a failing alternator.
Parasitic Drain Warning
A bad alternator can drain your battery even when the car is off. A failure in the internal diode assembly can create a "parasitic drain," leaving you with a dead battery overnight.
OEM vs. Aftermarket Alternators
For a vehicle from this era, finding a brand-new GM or ACDelco Original Equipment alternator is nearly impossible and would be very expensive if found as "New Old Stock." The market for the 1981-1986 Impala is dominated by new aftermarket and remanufactured aftermarket parts. A quality aftermarket unit from a trusted brand is the standard and most practical choice. While rebuilding the original Delco-Remy alternator is possible, the low cost and warranty of a complete replacement unit make it a better option for most owners.
Choosing the Right Aftermarket Alternator: Brand Tiers
Not all aftermarket brands are created equal. They generally fall into tiers based on quality, performance, and price.
Premium & High-Output Brands
Examples: Powermaster, Proform
These brands specialize in high-performance and upgraded alternators. They are an excellent choice if you have added electrical accessories like a powerful stereo, auxiliary lighting, or electric fans. Powermaster units are highly regarded, often look correct for restorations, and may come with an individual test sheet showing their output. Expect to pay more for this level of quality and performance.
OEM-Grade Aftermarket Brands
Examples: ACDelco, Bosch (New), Denso
These brands are known for producing high-quality parts that meet or exceed original factory specifications. ACDelco is GM's own parts brand, making it a natural and trusted choice for your Impala. New units from Bosch are also a reliable option. These brands provide a great balance of proven reliability and fair pricing.
Standard & Value Brands
Examples: Remy, WAI Global, BBB Industries, MPA, Store Brands (e.g., Duralast)
This category includes a mix of new and remanufactured units that offer a cost-effective solution. Remy was historically part of GM, and today they offer standard aftermarket replacements. Brands like WAI, BBB, and MPA are major suppliers to auto parts stores. While quality can be more variable than premium brands, they are an affordable way to get your car back on the road and typically come with a good warranty.
Check the Amperage and Clock Position
Your Impala likely came with a 63 or 78-amp alternator. If you've added electronics, upgrading to a higher-amp unit (like 100+ amps) is a good idea. Also, check the "clock position"—the orientation of the electrical plug on the back. Ensure your replacement matches the original to avoid fitment issues.
Typical Replacement Costs
The cost to replace the alternator in a 1981-1986 Impala is much more affordable than on a modern car. The part is easy to access and the job is straightforward.
| Part Type | Estimated Part Cost |
|---|---|
| New Aftermarket | $42 - $440 |
| Remanufactured | $70 - $250 |
| Used (from a salvage yard) | $40 - $80 |
| Shop Labor | $100 - $200 |
Frequently Asked Questions
How do I test my alternator?
With the engine off, a good battery should read 12.4-12.6 volts with a multimeter. Start the engine. The voltage at the battery should rise to between 13.7 and 14.7 volts. If the voltage doesn't rise or stays low, the alternator is likely bad.
Can I upgrade to a higher-amperage alternator?
Yes, and it's a common upgrade. The Delco-Remy 12SI is an improvement over the 10SI and provides better cooling and output. If you have added electrical accessories like a large stereo or electric cooling fans, upgrading to a 100-amp or higher alternator is highly recommended to handle the extra load.
What does alternator "clock position" mean?
The clock position refers to the orientation of the electrical plug on the back of the alternator case, viewed as if it were a clock face (e.g., 3 o'clock, 12 o'clock). Your wiring harness is designed for a specific position, so it's important to get a replacement that matches your original alternator to ensure the plug fits without stretching the wires.
Is a new or remanufactured alternator better?
For this vehicle, a new unit from a quality brand like ACDelco or Bosch is often preferred for peace of mind. However, a quality remanufactured alternator is a very common and reliable repair. Remanufactured units are disassembled, cleaned, and worn parts like bearings and brushes are replaced. Both new and remanufactured units from reputable brands come with warranties.
Technical Specifications
Common Factory Alternator Types: Delco-Remy 10SI, 12SI. Common Factory Amperages: 63A, 78A. Voltage: 12V Regulator: Internal
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Chevrolet Impala:
- 🛍️ Shop This Part
- Is Your Impala's Alternator Failing?
- Parasitic Drain Warning
- OEM vs. Aftermarket Alternators
- Choosing the Right Aftermarket Alternator: Brand Tiers
- Premium & High-Output Brands
- OEM-Grade Aftermarket Brands
- Standard & Value Brands
- Check the Amperage and Clock Position
- Typical Replacement Costs
- Frequently Asked Questions
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