Choosing the Right New Alternator for Your 1987 Chevrolet V20
Keep your classic Chevy truck's electrical system reliable with the correct new alternator.
- Failures are due to age; symptoms include dim lights, whining noises, and a dead battery.
- Replacement is a simple, one-hour DIY job for most owners.
- Choose a standard amp (63-78A) unit for a stock truck, but upgrade to 100A+ if you have added any electronics.
- New aftermarket units from brands like ACDelco or Bosch offer better reliability than most remanufactured options for this truck.
Is Your V20's Alternator Failing?
An alternator on a 1987 V20 rarely fails without warning. The truck's electrical system is simple, so problems are usually easy to spot. Look for these common symptoms before you get left on the side of the road.
- Dim or Flickering Headlights: This is a classic sign. You might notice your headlights seem weak at idle and then brighten when you rev the engine.
- Battery Warning Light: The 'BATT' or 'GEN' light on your dashboard may illuminate, indicating a charging system problem.
- Whining or Grinding Noises: A high-pitched whine or a grinding sound from the engine bay can point to failing bearings inside the alternator.
- Dead Battery: If your battery keeps dying even after being charged or jump-started, the alternator is likely not recharging it properly.
- Slow Electrical Accessories: You might notice your power windows operate slower than usual or the heater fan seems weak.
Pro Tip: How to Test Your Alternator
🎬 Watch this fast and simple guide to testing your alternator.You can do a quick check with a multimeter. With the engine off, a healthy battery should read about 12.6 volts. Start the engine. The voltage at the battery terminals should rise to between 13.7 and 14.7 volts. If the voltage stays in the 12-volt range or doesn't increase, the alternator isn't charging. Most auto parts stores also offer free alternator testing.
Choosing the Right Aftermarket Alternator for Your V20
For a classic truck like the 1987 V20, you don't need to hunt down an expensive original part. Today's aftermarket offers excellent options that often perform better than the original factory unit. The original Delco 10SI or 12SI alternators were often rated at 63 or 78 amps, which is low for modern needs. Your choice will depend on your truck's electrical demands.
Brand Quality Tiers
Not all aftermarket brands are the same. Here’s a breakdown of what to expect:
- Premium Brands (ACDelco, Bosch): ACDelco is the original equipment supplier for GM, so their parts offer a guaranteed fit and excellent reliability. Bosch is another top-tier brand known for high-quality electrical components that meet or exceed original specifications. Choose these for a stock or lightly modified truck for peace of mind.
- Standard Brands (WAI Global, BBB Industries, MPA, Remy): These brands offer a good balance of quality and value. For a daily driver or work truck, a new alternator from one of these brands is often a more reliable choice than a remanufactured unit, which can have a higher failure rate out of the box.
- High-Output & Performance (Powermaster, Proform): These brands specialize in alternators that produce more amperage than stock. If you've added a powerful stereo, extra lights, a winch, or an electric fuel pump, you need more power. A high-output alternator is a must to handle the extra electrical load and prevent problems.
Warning: High-Output Upgrades Need Better Wires
🎬 See how to perform the Big 3 wiring upgrade in minutes.If you install a high-output alternator (over 100 amps), you must upgrade your truck's main charging wires. This is often called the "Big 3 Upgrade" (alternator to battery positive, battery negative to chassis, and engine to chassis). The stock wiring is too small and can be damaged by the increased amperage.
Cost of a New Alternator for a 1987 Chevrolet V20
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Alternator | $47 - $263 |
| Remanufactured Alternator | $50 - $150 |
| Shop Labor for Installation | $100 - $200 |
Frequently Asked Questions
What amperage alternator do I need?
For a completely stock 1987 V20 with no added electronics, a standard replacement with 63 to 78 amps is sufficient. If you have added any accessories like a modern stereo, amplifier, off-road lights, or a winch, you should upgrade to an alternator with at least 100-140 amps to handle the extra demand.
Should I buy a new or remanufactured alternator?
For these trucks, new aftermarket alternators are affordable and widely available. New units from reputable brands generally offer better out-of-the-box reliability than remanufactured parts. While a remanufactured unit might be cheaper and come with a lifetime warranty, the hassle of a potential premature failure makes a new part a better investment for most owners.
What is a 'one-wire' alternator?
A one-wire alternator is a simplified design that only requires a single wire to be connected from the alternator's output post to the battery. They are popular for custom builds and engine swaps because of their simple wiring. Many high-output alternators from brands like Powermaster are offered in a one-wire configuration that is a direct fit for the V20.
Is replacing the alternator a difficult job? 🎬 Follow this step-by-step walkthrough for a Chevy truck alternator changeover.
No, on a 1987 V20, this is a straightforward job that most DIYers can complete in about an hour with basic hand tools. The process involves disconnecting the battery, loosening the belt tensioner to remove the drive belt, unplugging two electrical connectors, and removing a few mounting bolts.
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Technical Specifications
The original alternator was typically a Delco-Remy 10SI or 12SI model. Factory amperage ratings ranged from 63A to 105A, with 63A and 78A being common. Aftermarket replacements are available in various amperages, from stock replacement levels up to 200A or more for high-output applications.
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 V20:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your V20's Alternator Failing?
- Pro Tip: How to Test Your Alternator
- Choosing the Right Aftermarket Alternator for Your V20
- Brand Quality Tiers
- Warning: High-Output Upgrades Need Better Wires
- Cost of a New Alternator for a 1987 Chevrolet V20
- Frequently Asked Questions
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