2016 GMC Sierra 2500HD Spark Plug Specifications

Quick Reference: 2016 Sierra 2500HD Spark Plugs

This guide covers the gasoline engine option for the 2016 GMC Sierra 2500HD. Diesel engines do not use spark plugs.

Why the Right Spark Plug Matters

Choosing the correct spark plug is critical for engine health, performance, and fuel efficiency. It's not just about finding a plug that threads in; it's about thermal performance and electrical conductivity. The original equipment (OEM) plug for the 6.0L V8 is an iridium-tipped spark plug, chosen specifically by GM engineers for its durability and performance characteristics.

• Heat Range: A spark plug must transfer a specific amount of heat away from the firing tip to the cylinder head. A plug that is too "hot" (doesn't transfer heat well) can lead to pre-ignition and detonation, causing severe engine damage. A plug that is too "cold" (transfers too much heat) can develop carbon fouling, leading to misfires. The OEM plug has the correct heat range for all expected operating conditions.
• Electrode Material:
  • Iridium: The OEM choice for a reason. Iridium has an extremely high melting point and is incredibly hard, allowing for a very fine-wire center electrode. This design requires less voltage to create a spark, provides a more focused and consistent spark kernel, and offers a service life of up to 100,000 miles.
  • Platinum: A good alternative, often used as an OEM plug in slightly older vehicles. Platinum offers a long service life (typically 60,000-80,000 miles) but doesn't quite match the durability or performance of iridium.
  • Copper: The classic choice. Copper plugs have excellent conductivity but a much shorter lifespan, often requiring replacement every 20,000-30,000 miles. They are not recommended for the 2016 Sierra's ignition system, which is designed for long-life iridium plugs.

How to Gap a Spark Plug

Properly gapping a spark plug ensures the spark has the optimal distance to travel, creating the most efficient combustion event. While premium iridium plugs like the ACDelco 41-114 come pre-gapped, it's wise to verify the gap before installation.

Caution: The fine-wire iridium tip is fragile. Never use a "coin-style" gapper tool, as it can easily break the center electrode. Always use a feeler gauge or a wire-loop gapping tool.

1. Slide the correct gauge (0.040") between the center electrode and the ground strap (the bent metal piece over the top).
2. The gauge should slide through with a slight drag. If it's too loose or too tight, you need to adjust.
3. To adjust, gently tap the side of the ground strap on a hard surface to close the gap, or carefully bend it open with the notch on a gapping tool. Never pry against the center electrode.

Replacement Procedure Tips

The 6.0L Vortec V8 in the Sierra HD is a straightforward engine to service. It uses a modern coil-on-plug ignition system, meaning each spark plug has its own dedicated ignition coil right on top of it.

• Coil-on-Plug Removal: To access the spark plug, first, disconnect the electrical connector from the ignition coil. Then, remove the single bolt (typically a 10mm head) holding the coil to the valve cover. Gently twist and pull the coil straight up to remove it from the spark plug.
• The Anti-Seize Debate: Modern ACDelco and NGK plugs feature a special trivalent or nickel plating that acts as a release agent. This plating is designed to prevent seizing in the aluminum cylinder heads. For this reason, do not use anti-seize compound on the threads of the OEM-style plugs. The lubricant effect of anti-seize can cause you to over-torque the plug, potentially stretching the threads in the cylinder head or damaging the plug itself. Always follow the torque spec on a clean, dry thread.
• Dielectric Grease: A small amount of dielectric grease applied to the inside of the spark plug boot (the end of the coil that fits over the plug) is highly recommended. This grease prevents the boot from sticking to the plug's porcelain, seals out moisture, and prevents high-voltage leaks. Do not apply it to the plug threads or electrodes.

Known Issues

Technicians and DIYers can rest easy. The GM 6.0L V8 is not associated with the major spark plug-related issues that plague some other engines of the era.

• No Broken Plugs: This engine does not suffer from the infamous issue of two-piece spark plug shells breaking off in the cylinder head, a problem commonly associated with Ford 3-valve Triton engines from the mid-2000s.
• Robust Ignition System: The coil-on-plug system is reliable and does not have widespread known faults like ionization-sensing failures seen on some other GM engine families.

Changing the plugs on your 2016 Sierra 2500HD is a very manageable task with the right tools and information, ensuring your truck runs smoothly for another 100,000 miles.

Need plugs replaced? Find a shop on Repairius.