2017 Ford Transit Spark Plug Specifications

Quick Reference: 2017 Ford Transit Spark Plugs

Note: The 3.2L Power Stroke is a diesel engine and does not use spark plugs. Data is for original equipment iridium plugs. Always verify part numbers and specifications with your vehicle's owner's manual or a certified parts professional before beginning work.

Why the Right Spark Plug Matters

Choosing the correct spark plug is critical for engine performance, fuel economy, and longevity. It's not just a matter of finding one that threads in. Key factors include:

• Heat Range: This is the plug's ability to dissipate heat. A plug that is too "hot" (doesn't dissipate heat well) can lead to pre-ignition (detonation), causing severe engine damage. A plug that is too "cold" can accumulate deposits and foul, leading to misfires. The factory-specified heat range is engineered for your engine under a wide variety of operating conditions.
• Electrode Material: The 2017 Transit engines came from the factory with long-life iridium-tipped spark plugs. These are designed for extended service intervals, often up to 100,000 miles.
  • Iridium/Platinum: These precious metals have very high melting points and offer excellent resistance to wear, making them ideal for modern coil-on-plug ignition systems with high voltage. They maintain a precise gap for a very long time, ensuring a consistent spark.
  • Copper: While once the standard, conventional nickel/copper plugs have a much shorter service life (typically 20,000-30,000 miles). Using them in a modern engine designed for iridium plugs will result in premature wear, misfires, and poor fuel economy long before the factory-recommended service interval.

How to Gap a Spark Plug

Even though most premium plugs like the Motorcraft or NGK iridium units come pre-gapped, it is essential to verify the gap before installation. A drop during shipping can easily close the gap.

1. Use the Right Tool: Use a feeler gauge or a dedicated wire-style spark plug gapper. Do NOT use the old-style "coin" gapper, as it can damage the fragile iridium tip on the center electrode.
2. Measure Carefully: Slide the correct wire gauge between the center and ground electrodes. You should feel light drag. If it's too tight or too loose, it needs adjustment.
3. Adjust Gently: To adjust, gently bend the ground strap (the L-shaped electrode) only. Use the slot in your gapping tool to carefully pry it open or gently tap it on a hard surface to close it. Never put pressure on the center electrode or its ceramic insulator.

Replacement Procedure Tips for 2017 Transit

Both the 3.7L V6 and 3.5L EcoBoost engines use a modern coil-on-plug ignition system, which simplifies the job.

• Coil-on-Plug (COP) Removal: Each spark plug has its own ignition coil mounted directly on top of it. Begin by disconnecting the electrical connector from the coil. Then, remove the single small-bore bolt (usually 8mm) holding the coil in place. Gently twist and pull the coil straight up to remove it. The spark plug is now accessible deep in the spark plug well.
• The Anti-Seize Debate: This is a hotly debated topic. Most modern spark plugs, including the OEM Motorcraft plugs, have a special trivalent or nickel plating that acts as an anti-seize coating. For these plugs, applying additional anti-seize lubricant is not recommended. The lubricant can alter the final torque value, leading to over-tightening and potential thread damage in the aluminum cylinder head. It can also contaminate the firing end of the plug. Our recommendation: Install them clean and dry, and torque to spec.
• Dielectric Grease: A small amount of dielectric grease applied to the inside of the rubber boot on the ignition coil is highly recommended. This grease prevents the boot from getting stuck to the spark plug's porcelain, seals out moisture, and prevents voltage leaks. Do not put it on the electrical connector pins.

Known Issues

While Ford has a history with problematic spark plugs—namely the infamous two-piece plugs used in earlier 3-valve Modular V8 engines that were prone to breaking off in the cylinder head—the 2017 Transit's 3.7L and 3.5L EcoBoost engines do not use this design. They use a conventional one-piece shell design that is not prone to breakage when removed with standard care and procedure. Always work on a cold engine to prevent any issues with aluminum threads.

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