Choosing the Right Alternator for Your 1987 GMC R1500
Keep your classic GMC truck's electrical system reliable with the right new alternator.
- Symptoms include dim lights, a dashboard warning light, whining noises, and a dead battery.
- Replacement is simple and a good DIY project for most owners.
- Consider upgrading to a higher-amperage alternator if you have added electrical accessories.
- Choose a quality aftermarket brand like ACDelco, Bosch, or Remy for reliability.
Signs of a Failing Alternator on Your R1500
On a straightforward truck like the 1987 R1500, the signs of a bad alternator are usually obvious. Your truck is trying to tell you something is wrong.
- Dim or Flickering Lights: One of the first things you'll notice is headlights and dashboard lights that are dim, flicker, or get brighter when you rev the engine. This means the alternator isn't providing consistent power.
- "GEN" or Battery Warning Light: Your dashboard has a warning light that may say "GEN" (Generator) or show a battery symbol. If this light comes on and stays on while you're driving, it's a direct warning that the charging system has a problem.
- Whining or Grinding Noises: A high-pitched whine that changes with engine speed often points to a bad bearing or internal component in the alternator. A grinding or rumbling noise can mean the bearings are completely worn out.
- Dead Battery: If you find yourself with a dead battery, especially if the battery is fairly new, the alternator is the likely culprit. It's not recharging the battery as you drive, leaving you unable to start the truck. 🎬 Watch: Diagnosing bad alternator symptoms on a classic Chevy truck.
- Electrical Problems: The radio may cut out or the power windows (if equipped) might be slow. These are signs that there isn't enough electrical power to go around.
Choosing Your New Aftermarket Alternator
For a 1987 GMC R1500, you have many excellent aftermarket choices that meet or exceed original quality. The original Delco-Remy alternators (often CS130 or similar models) were good, but modern aftermarket units often have better technology and higher output.
Pro Tip: Consider an Amperage Upgrade
The stock alternator on your truck likely had an output between 78 and 105 amps. If your truck is stock, a replacement in this range is fine. However, if you've added accessories like a modern stereo, a winch, or extra lighting, you should upgrade to a higher-output alternator (140 amps or more). This provides the power your accessories need without draining the battery. If you install a high-output alternator, you must also upgrade the main charging wire to handle the extra power safely.
🎬 See how to upgrade and clock your square body alternator.Brand Quality Tiers
Not all brands are created equal. Here’s how the available brands generally stack up for your truck:
- Premium Brands (OEM Equivalents & High-Performance):
- ACDelco: As GM's original parts supplier, ACDelco is a trusted choice for a direct-fit, reliable replacement. They offer different lines, with their Professional (Gold) series being a top-tier option.
- Bosch: A global leader in automotive parts, Bosch offers high-quality new and remanufactured alternators known for reliability.
- Powermaster: If you need a high-output alternator for added accessories, Powermaster is a specialty brand that focuses on performance and high-amperage units.
- Standard-Tier Brands (Great Value):
- Remy: Historically linked to GM as Delco-Remy, Remy is a well-known brand that provides quality, reliable alternators that are a good balance of price and performance.
- WAI Global & BBB Industries: These are major aftermarket manufacturers that produce dependable alternators for a wide range of vehicles. They are a solid choice for a standard replacement.
- Specialty & Economy Brands:
- MPA (Motor Parts of America): A large producer of remanufactured units.
- Proform: Often focuses on performance and appearance parts, like chrome-finished alternators.
Replacement Cost
Replacing the alternator on a 1987 R1500 is a common repair. The parts are affordable and the labor is straightforward. Below are estimated costs.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Alternator | $47 - $263 |
| Shop Labor | $100 - $200 |
| Total Estimated Cost | $147 - $463 |
Frequently Asked Questions (FAQ)
How do I know if it's the alternator or the battery?
A simple test is to start the truck and then disconnect the negative battery terminal. If the truck immediately stalls, the alternator is bad. If it keeps running, the alternator is likely working, and your battery may not be holding a charge. You can also use a multimeter: a healthy battery should read about 12.6 volts with the engine off, and the charging system should read between 13.8 and 14.4 volts with the engine running.
Is it hard to replace the alternator on my 1987 R1500?
No, this is a great DIY job for a beginner or intermediate mechanic. Access is generally good, and the process involves disconnecting the battery, loosening the belt tensioner to remove the serpentine belt, unplugging a couple of wires, and removing two or three bolts.
🎬 Watch this step-by-step guide to testing and replacing your alternator.Do I need a special tool to remove the belt?
Usually, no. The spring-loaded belt tensioner can typically be moved with a standard ratchet or breaker bar to create slack in the belt.
Are there any recalls on the 1987 GMC R1500 alternator?
No, searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls or specific investigations related to the alternator for the 1987 GMC R1500.
Helpful Videos
Technical Specifications
The 1987 GMC R1500 typically uses a Delco CS130 family alternator. It features an internal regulator and a 6-groove serpentine pulley. Amperage ratings for stock replacements typically range from 78A to 105A, with high-output options available up to 250A or more.
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.
- GMC R1500: