Choosing the Right Spark Plugs for Your 1987-1995 Chevrolet Blazer
Keep your Blazer's engine running smoothly with the right set of new spark plugs.
- For best results, use OEM-equivalent ACDelco or high-quality NGK spark plugs.
- Be prepared for the challenge of replacing the #3 spark plug; loosening the steering shaft is the recommended method for access.
- Choose your plug type based on your budget and desired maintenance interval; iridium and platinum plugs last much longer than basic copper ones.
- Always verify the spark plug gap before installation; specifications can vary between model years and plug manufacturers.
Signs of Failing Spark Plugs
When your spark plugs are worn out, your Blazer will let you know. The signs can start small but will get worse over time. Ignoring them can lead to poor performance and potentially damage other parts of your ignition system.
- Rough Idle: The engine may shake or vibrate when you're stopped.
- Engine Misfires: You might feel a stutter or hesitation from the engine, especially when accelerating. This can trigger a check engine light with codes like P0300 (random misfire) or P0301-P0306 for specific cylinders.
- Trouble Starting: A weak spark makes it harder for the engine to start, particularly in cold weather.
- Reduced Fuel Economy: When fuel isn't burned completely due to a weak spark, your truck uses more gas.
- Poor Acceleration: A noticeable lack of power when you press the gas pedal is a common symptom.
Choosing the Right Aftermarket Spark Plug
For the 1987-1995 Blazer, you have several good aftermarket options. The original ACDelco plugs are a safe bet, but some aftermarket brands offer longer life and excellent performance.
Brand Quality Tiers
- OEM & Premium Aftermarket (Best Choice): Brands like ACDelco, NGK, and Denso are highly recommended by Blazer owners and mechanics. ACDelco is the original equipment manufacturer, and many consider NGK to be an upgrade. These brands use high-quality materials like iridium and platinum, which last much longer than traditional copper plugs.
- Standard Aftermarket (Good Choice): Autolite and Champion offer reliable performance at a more budget-friendly price. They are a solid choice for regular maintenance, though their copper plugs may need to be changed more frequently (every 25,000-30,000 miles).
- Performance Brands: Brands like MSD and Accel are geared towards modified or high-performance engines and are generally not necessary for a stock daily-driven Blazer.
- Brands to Approach with Caution: Some owners in forums have reported issues when using Bosch spark plugs in GM's 4.3L V6 engine, sometimes leading to misfires. It's often best to stick with ACDelco or NGK for proven compatibility.
Installation Warning: The #3 Spark Plug
Replacing the spark plugs on the 4.3L V6 engine has one major challenge: the #3 spark plug. This is the middle plug on the driver's side. It is notoriously difficult to access because the steering shaft is directly in the way. While some try to work around it with special swivels and sockets, many mechanics find it easier to unbolt the steering shaft (one 11mm bolt) and move it aside for clear access. 🎬 Watch: How to remove the difficult #3 spark plug This makes the job much less frustrating.
Cost of New Spark Plugs (1987-1995 Chevrolet Blazer)
| Plug Type | Price Range (Per Plug) | Typical Lifespan |
|---|---|---|
| Copper (e.g., NGK V-Power, Standard Autolite) | $3 - $6 | 25,000 - 30,000 miles |
| Platinum / Double Platinum (e.g., ACDelco Professional) | $6 - $15 | 60,000 - 100,000 miles |
| Iridium (e.g., NGK Iridium IX, ACDelco Iridium) | $8 - $20+ | 100,000+ miles |
Note: Prices are estimates and can vary by brand and retailer. Your Blazer requires six spark plugs. 🎬 See this full spark plug replacement walkthrough for the 4.3L V6
Pro Tip: Check the Gap
Always check the spark plug gap before installation, even if the box says they are "pre-gapped." Use a feeler gauge or wire-type gapping tool. For 1987-1994 models, the gap is typically 0.035". For 1995 models, it is 0.045". However, some modern replacement plugs specify a 0.040" gap. It's best to follow the specification listed for the new plug you are installing.
Frequently Asked Questions
How often should I change the spark plugs on my Blazer?
It depends on the type of plug. Standard copper plugs should be changed every 25,000 to 30,000 miles. More expensive platinum and iridium plugs can last much longer, often up to 100,000 miles.
What tools do I need to change the spark plugs?
You will need a ratchet, a 5/8" spark plug socket, various extensions, and a universal joint/swivel. You'll also need a torque wrench for proper tightening and a spark plug gap tool. To access the difficult #3 plug, an 11mm wrench or socket is needed to loosen the steering shaft bolt.
🎬 Watch: Another helpful trick for changing the #3 spark plugShould 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, apply only a very small amount to the threads and reduce the final torque by about 10-15% to avoid over-tightening.
Do I need to put dielectric grease on the spark plug boots?
Yes, it is highly recommended. Applying a small amount of dielectric grease inside the spark plug wire boot prevents it from getting stuck to the plug, seals out moisture, and ensures a good electrical connection.
Helpful Videos
Technical Specifications
OEM Part Numbers: 19302741
Spark Plug Gap: - 1987-1994 Models: 0.035 in (0.89 mm) - 1995 Models: 0.045 in (1.14 mm) Socket Size: 5/8 in.
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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.
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