2017 Ram 2500 Spark Plug Type & Gap

Quick reference

Engine	OEM Plug PN (Mopar)	Aftermarket (NGK/Denso)	Gap (in/mm)	Torque (lb-ft / Nm)	Interval (miles/km)
5.7L HEMI V8	SP000416AA	NGK LZFR5C-11 / Denso 5304 (FXE20HR11)	0.043 in / 1.1 mm	13 lb-ft / 18 Nm	30,000 miles / 48,000 km
6.4L HEMI V8	SP143877AA	NGK LKR8A / Denso 4704 (FXE22HR11)	0.043 in / 1.1 mm	13 lb-ft / 18 Nm	30,000 miles / 48,000 km

Note: The 6.7L Cummins Diesel engine does not use spark plugs.

Why the right plug matters

Choosing the correct spark plug for your 2017 Ram 2500 is more critical than you might imagine. It’s not just about a spark; it’s about a precisely timed, correctly sized, and sufficiently strong spark. Using the wrong spark plug can lead to a host of problems, from decreased fuel economy and reduced engine performance to misfires, premature wear, and even catastrophic engine damage.

Heat range

Spark plugs are designed with a specific "heat range," which refers to their ability to dissipate heat from the combustion chamber. A "hot" spark plug retains more heat, while a "cold" spark plug transfers more heat away.

• Too hot: Can lead to pre-ignition (fuel igniting before the spark) or detonation (uncontrolled inflammation of the air-fuel mixture), causing severe engine damage.
• Too cold: Can lead to fouling, where carbon deposits build up on the plug, causing misfires and poor performance.

Your Ram’s engine is engineered for a specific heat range, so always stick to the OEM-recommended plugs or their direct aftermarket equivalents.

Electrode metal (Iridium vs. Platinum vs. Copper)

Spark plug electrodes come in various materials, each with unique properties affecting durability and performance:

• Copper: These are excellent conductors but softer, leading to faster wear. They are typically found in older vehicles or those with high-performance applications requiring frequent changes. The 2017 Ram 2500 Hemi engines utilize copper core plugs with a nickel alloy coating for durability, which is why their replacement interval is shorter.
• Platinum: Platinum is harder and has a higher melting point than copper, allowing for finer electrodes and longer service intervals. Double-platinum plugs offer even greater longevity.
• Iridium: This is the hardest and most durable material used for spark plug electrodes, enabling the finest wire tips for the most focused spark. Iridium plugs offer the longest service life and are often found in modern engines with extended maintenance schedules.

The 2017 Ram 2500 Hemi engines, both 5.7L and 6.4L, are designed for and come with copper-nickel alloy spark plugs from the factory. While platinum or iridium plugs might offer longer life in some applications, using them in these Hemi engines is not recommended unless specifically stated by the manufacturer. The ignition system and combustion characteristics are optimized for the factory-spec copper-nickel plugs, and substituting them can sometimes lead to less efficient combustion or misfires, especially if the plug characteristics (like resistance) differ.

How to gap a spark plug

Proper spark plug gap is crucial for optimal combustion. The gap dictates the distance the spark must jump, directly affecting the spark's intensity and duration. All 2017 Ram 2500 Hemi engines require a 0.043 inch (1.1 mm) gap.

Tools you'll need

• Wire-style spark plug gap gauge: These are generally more accurate for fine-wire electrodes than coin-style gauges, which can damage the delicate tips.

Gapping procedure

1. Check the gap: Gently slide the appropriate wire gauge through the spark plug gap. There should be a slight drag.
2. Adjust if necessary: If the gap is too small, use the gapping tool's electrode bending slot to carefully and gently pry the ground electrode open. Make very small adjustments.
3. Close the gap (if needed): If the gap is too wide, gently tap the ground electrode on a clean, hard surface to close it. Be extremely careful not to damage the center electrode or insulator.
4. Re-check: Always re-check the gap after any adjustment. Repeat until the gap is precisely within specification.

A note on pre-gapped plugs: While many modern spark plugs claim to be "pre-gapped," it's always a good practice to verify the gap before installation, as shipping and handling can sometimes alter it.

Replacement procedure tips

Replacing spark plugs on your 2017 Ram 2500's Hemi engine is a moderately challenging DIY task. These engines use a coil-on-plug (COP) ignition system, meaning each spark plug has its own ignition coil mounted directly on top.

1. Access: The spark plugs are located under the ignition coils, which are typically secured with a single bolt. You'll need to remove the engine cover (if equipped) and disconnect the electrical connector from each coil.
2. Coil removal: Carefully twist and pull the ignition coil straight up to remove it. Avoid prying, as this can damage the coil boot or the spark plug below.
3. Spark plug removal: Use a spark plug socket with a rubber insert to grip the plug. Turn counter-clockwise to loosen and remove. It's best to allow the engine to cool down significantly before attempting removal to prevent the possibility of damaging the cylinder head threads.
4. Anti-seize debate: There's ongoing debate regarding the use of anti-seize on spark plug threads. Mopar (and many spark plug manufacturers) often advise against it for modern spark plugs with nickel-plated shells. The nickel plating acts as an anti-seize agent itself, and adding more can lead to over-torquing, which can damage the cylinder head or the plug. If you choose to use anti-seize, apply a very thin coat to the threads, avoiding the electrode, and reduce the torque specification by approximately 15-20%.
5. Dielectric grease: Apply a small amount of dielectric grease inside the spark plug boot (the part of the coil that fits over the plug). This helps seal out moisture, prevents corrosion, and makes future removal easier. Do not apply dielectric grease to the spark plug threads.
6. Installation: Hand-thread the new spark plugs to avoid cross-threading. Once finger-tight, use a torque wrench to tighten them to the specified 13 lb-ft (18 Nm). Over-tightening can strip threads or crack the spark plug insulator.

Known issues

Fortunately, the 2017 Ram 2500 Hemi engines are not widely known for specific, widespread spark plug-related issues like the notorious two-piece spark plug breakage seen in some older Ford 3-valve engines.

However, general issues that can occur with any spark plug replacement include:

• Cross-threading: This happens when the spark plug is not threaded straight into the cylinder head, damaging the threads on both the plug and the head. Always start plugs by hand.
• Over-torquing or under-torquing: Over-torquing can strip threads or crack the plug insulator. Under-torquing can lead to compression leaks, misfires, or the plug backing out.
• Cracked porcelain: Dropping a spark plug or mishandling it can crack the porcelain insulator, leading to misfires as the spark diverts to the crack instead of jumping the gap.

Always use care when handling and installing new spark plugs.

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