Choosing a New Aftermarket Alternator for Your 1983-1989 Chevrolet P20
Keep your workhorse P20 charging correctly by picking the right new alternator for the job.
- A new aftermarket alternator is a cost-effective and reliable choice for this vehicle.
- Symptoms like dimming lights, a battery warning light, and whining noises point to a failing alternator.
- Verify your amperage needs and the electrical connector's 'clock position' before ordering.
- For P20s with heavy electrical loads (RVs, work trucks), consider a high-output alternator.
Is Your P20 Alternator Failing?
The alternator on the 1983-1989 Chevrolet P20 is a straightforward, hardworking part. But like any component, it wears out. Given the age of these vehicles, an alternator failure is not a matter of if, but when. Recognizing the signs early can save you from a breakdown.
Common symptoms include headlights that dim at idle and brighten when you rev the engine, a battery warning light on the dash, or a whining noise from the engine that changes with RPMs. You might also find the engine is slow to crank or the battery is frequently dead, even if it's new. These are all classic signs that the alternator isn't producing enough power to run the vehicle and charge the battery.
Don't Mistake a Bad Battery for a Bad Alternator
A dead battery is a common symptom of a failing alternator, but the battery itself might be the problem. Before replacing the alternator, it's wise to have your battery tested. Most auto parts stores offer this service for free. A simple voltage test can also help diagnose the issue: a healthy battery should read about 12.6 volts with the engine off, and between 13.0 and 15.3 volts with the engine running. If the voltage doesn't increase when the engine is on, the alternator is likely the culprit.
Choosing the Right Aftermarket Alternator
For a vehicle like the P20, you don't need to hunt down a rare, expensive original equipment (OE) part. New aftermarket alternators offer excellent quality, often meeting or exceeding the original specifications, at a much lower cost. The alternators used in this era of GM trucks are typically Delco 10-SI or 12-SI series models, which are widely available. Here’s a look at the brands available and their general reputation:
- Premium Brands (Bosch, Remy, ACDelco): These brands are well-regarded in the industry. ACDelco is GM's own parts division, so their products are often considered a direct OE-equivalent. Bosch and Remy also have long histories of producing quality electrical components. Choosing a new unit from one of these brands is a solid bet for longevity and reliability.
- Standard Brands (WAI Global, BBB Industries, MPA): These brands offer a good balance of quality and price. WAI Global is known for testing its new units individually before they ship. BBB Industries is another common name in the aftermarket. These are dependable choices for a daily driver or work vehicle.
- High-Output & Specialty Brands (Proform): Some brands, like Proform, specialize in high-performance or high-output alternators. If your P20 has been converted into an RV or food truck with significant extra electrical loads (like inverters, refrigerators, or extra lights), you may need a high-output alternator with a higher amperage rating. Standard alternators for this vehicle are often around 94 or 105 amps, but high-output versions can go much higher. Upgrading may require a shorter belt or wiring modifications.
Check the Amperage and Clock Position
When ordering, make sure the amperage of the new alternator meets your needs. A stock replacement is fine for a stock truck, but added accessories require more power. Also, pay close attention to the "clock position" of the electrical connector on the back. Note the position on your old alternator (imagine the back of it as a clock face) and order a new one that matches to ensure a simple, direct fit.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Alternator | $47.39 - $255.14 |
| Shop Labor for Installation | $100 - $200 |
Frequently Asked Questions
Do I need a special high-output alternator?
Only if you have added significant electrical accessories. If your P20 is a standard cargo van, a stock amperage (e.g., 94-105 amp) replacement is sufficient. If it's an RV or work truck with inverters, extra lighting, or other power-hungry equipment, a high-output alternator (140 amps or more) is a wise investment to prevent electrical issues.
Are there any recalls for the P20 alternator?
No specific recalls or Technical Service Bulletins (TSBs) were found for the 1983-1989 Chevrolet P20 alternator. Searches on the National Highway Traffic Safety Administration (NHTSA) website did not show any relevant actions for this specific vehicle and part from this era.
Is it difficult to replace the alternator on a P20?
For a moderately experienced DIYer, this is a very feasible job. Access in the large engine bay of a P20 is generally good. The process typically involves disconnecting the battery, releasing the tension on the drive belt, removing a few bolts, and swapping the electrical connections. It usually takes about an hour.
Should I buy a new or remanufactured alternator?
While remanufactured parts can be a good value, the quality can be inconsistent. Given the affordable price range of brand-new aftermarket units for the P20, opting for a new alternator is generally the safer choice. It eliminates the risk of getting a poorly rebuilt part and often comes with a better warranty.
Technical Specifications
Commonly uses a Delco 10-SI or 12-SI series alternator. Standard amperage ratings are typically 94A or 105A. Voltage is 12V. Clock position of the rear connector must match the original for proper fitment.
We Have This Part in Stock
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 P20: