Choosing the Right Spark Plugs for Your 1982-1990 GMC S15
Keep your classic GMC S15 running strong by picking the best spark plugs for its specific engine.
- Stick with standard copper-core spark plugs from reputable brands like ACDelco, NGK, or Champion for the best performance in these older engines.
- Always check and adjust the spark plug gap to your engine's specific requirements before installation.
- If you have a V6 engine, be prepared for a challenge with the rear plugs and the one near the steering shaft; accessing them through the wheel well can help.
- Replacing plugs every 30,000 miles is cheap insurance to keep your S15 running smoothly and efficiently.
Signs of Failing Spark Plugs
When your spark plugs start to wear out, your truck will give you signs. Worn plugs can't create a good spark, which means fuel doesn't burn completely in the cylinders. You might notice one or more of these symptoms:
- Rough Idling: The engine may shake or vibrate more than usual when you're stopped.
- Trouble Starting: The engine may take longer to crank over before it starts, or it might not start at all.
- Engine Misfires: You might feel a stumbling or hesitation from the engine while driving as a cylinder fails to fire correctly.
- Poor Acceleration: The truck may feel sluggish and lack the power it used to have.
- Worse Fuel Economy: You'll find yourself filling up the gas tank more often because the engine is running inefficiently.
Choosing the Right Aftermarket Spark Plug
For a 1982-1990 GMC S15, you don't need to overspend on fancy spark plugs. These engines were designed in an era of simpler technology and run best on the type of plugs they came with from the factory: standard copper-core plugs. While platinum and iridium plugs last longer, they don't always offer a performance benefit in older engines and are not necessary.
Brand Quality Tiers for GMC S15
| Tier | Brands | Notes |
|---|---|---|
| Best Bet (OEM & Top Tier) | ACDelco, NGK | ACDelco was the original part for your truck and is always a safe choice. NGK is a highly respected brand that many owners consider an upgrade, known for quality and consistent performance. |
| Good Quality & Value | Champion, Denso, Autolite | These brands offer reliable, standard copper plugs that work very well in the S15's engines. Champion is a classic American brand that has been around for ages and is a perfectly good choice for a stock truck. |
| Performance/Specialty | Bosch, MSD | Bosch is a major innovator in spark plugs, and MSD is known for performance ignition systems. These are solid choices, but for a daily-driven S15, they may not provide a noticeable difference over the other tiers to justify any extra cost. |
Pro Tip: Check The Gap! Always check the spark plug gap before installation, even if the box says they are "pre-gapped". The gap setting is different depending on your engine (1.9L, 2.0L, 2.5L, 2.8L, or 4.3L). Use a feeler gauge or gapping tool to adjust the gap to the exact specification listed on the sticker under your truck's hood or in your service manual.
Known Issues & Recalls
There are no known recalls or technical service bulletins (TSBs) from the NHTSA related to spark plugs for the 1982-1990 GMC S15. The main issue owners report is difficulty accessing some of the spark plugs, especially on the V6 engines. On the 4.3L V6, the #3 spark plug (middle plug on the driver's side) is notoriously tight due to the steering shaft being in the way. This may require special tools like a shorter spark plug socket or a combination of wrenches to remove and replace. Accessing the plugs through the front wheel wells often makes the job easier.
Frequently Asked Questions (FAQ)
How often should I change the spark plugs on my S15?
For standard copper spark plugs, a good interval is every 30,000 miles or every 2-3 years. This ensures your engine always has a strong spark and runs at its best. Since they are inexpensive, changing them regularly is cheap insurance against performance problems.
Should I use anti-seize on the new spark plugs?
This is a debated topic. Some plug manufacturers, like NGK, advise against it because their plugs have a special plating that prevents seizing. If you do use anti-seize, use a very small amount on the threads only, and be aware that you should reduce the final torque setting slightly to avoid over-tightening.
What tools do I need to change my spark plugs?
You will need a ratchet, a few extensions, a spark plug socket (which has a rubber insert to protect the plug), a spark plug gapping tool, and possibly a swivel socket for hard-to-reach plugs. For V6 models, a combination of different length extensions and wrenches can be helpful for the plugs near the back of the engine and the steering shaft.
What is the firing order for my engine?
The firing order is critical for making sure the spark plug wires go back on in the correct sequence. The order varies by engine. For example, the 2.8L V6 is 1-2-3-4-5-6, while the 4.3L V6 is 1-6-5-4-3-2. It's best to replace one plug and wire at a time to avoid any mix-ups.
Technical Specifications
OEM Part Numbers: ACDelco CR43TS ACDelco R43TS ACDelco 41-803
Spark plug gap and heat range vary significantly between the 1.9L, 2.0L, 2.5L, 2.8L, and 4.3L engines. Always verify the correct part number and gap specification for your specific engine using the under-hood emissions sticker or a reliable parts catalog. Common gaps range from 0.035" to 0.060".
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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.
- GMC S15: