2021 Ram ProMaster Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2021 Ram ProMaster is crucial for optimal engine performance, fuel efficiency, and longevity. The spark plug's primary job is to ignite the air-fuel mixture in the combustion chamber, creating the power that drives your vehicle. Several factors make a difference, including heat range and electrode material.

Heat Range: Spark plugs are designed with a specific "heat range" – essentially, how quickly they dissipate heat from the combustion chamber. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition or knocking, damaging your engine. A plug that's too "cold" (dissipates heat too quickly) can foul with carbon deposits, leading to misfires. Your ProMaster's engine is designed to operate with a specific heat range, and using a plug outside this range can cause problems.

Electrode Metal: The material used for the center and ground electrodes significantly impacts plug life and performance.

• Iridium: These are the most advanced and longest-lasting spark plugs. Iridium is extremely hard and has a very high melting point, allowing for very fine electrodes that produce a strong, consistent spark. They offer excellent performance and fuel economy and are typically rated for 100,000 miles or more, as recommended for your ProMaster.
• Platinum: Platinum plugs offer good durability and performance, lasting longer than copper plugs. They are a step up from copper but typically don't match the lifespan of iridium.
• Copper: While excellent conductors of electricity, copper plugs wear out more quickly due to the softer nature of the metal. They often require more frequent replacement, making them less suitable for modern engines like those found in the ProMaster, which are designed for long-life iridium plugs.

How to gap a spark plug

The gap between the center and ground electrodes of a spark plug is critical for a strong, consistent spark. Even though many modern iridium spark plugs come pre-gapped, it's always a good idea to double-check the gap before installation, especially with replacement plugs. For your 2021 Ram ProMaster, the recommended gap is 0.043 inches (1.1 mm).

To gap a spark plug, you'll need a wire-type spark plug gapping tool. Avoid using disk-style gapping tools on fine-wire iridium plugs, as they can damage the delicate electrode.

1. Check the gap: Slide the correct size wire gauge from your gapping tool into the spark plug gap. It should slide in with slight resistance.
2. Adjust the gap (if necessary): If the gap is too small, gently pry the ground electrode open slightly with the gapping tool. If the gap is too large, gently tap the ground electrode on a hard, non-abrasive surface to close it incrementally. Always make small adjustments to avoid over-bending the electrode.
3. Re-check: Re-check the gap until it meets the specified measurement.

Replacement procedure tips

Replacing spark plugs on your 2021 Ram ProMaster's 3.6L Pentastar V6 engine is a manageable task for the DIY mechanic, but some tips can make it smoother:

• Coil-on-Plug Removal: The 3.6L Pentastar engine uses a coil-on-plug (COP) ignition system, meaning each spark plug has its own ignition coil directly mounted on top of it. To access the spark plugs, you'll need to disconnect the electrical connector from each coil and then carefully pull the coil pack straight up and off the spark plug. Take care not to damage the wiring or the coil boots.
• Anti-Seize Debate: There's an ongoing debate about using anti-seize compound on spark plug threads. For spark plugs with a special coating from the factory (common on new iridium plugs), many manufacturers, including NGK, recommend against using anti-seize, as it can interfere with the plug's torque-to-yield design and lead to over-tightening. If your new plugs do not have this coating, a tiny amount of anti-seize can be used on the threads to prevent them from seizing in the cylinder head. However, if you choose to use it, reduce the recommended torque spec by about 10-20% to compensate for the lubricity of the anti-seize.
• Dielectric Grease on Boots: Applying a small amount of dielectric grease inside the spark plug boot (the end that connects to the spark plug) can help prevent moisture intrusion, prevent corrosion, and make future removal easier. Be careful not to get grease on the electrodes of the spark plug.

Known issues

Fortunately, the 3.6L Pentastar V6 engine in the 2021 Ram ProMaster is not commonly known for specific spark plug-related issues like the Ford 3-valve modular engine's two-piece plug breakage. However, always exercise caution during removal and installation to prevent any damage to the plugs or cylinder head threads.

Need plugs replaced? Find a shop on Repairius.