2018 Ford F-250 Super Duty: Spark Plug Type, Gap & Torque

Quick Reference

Why the right plug matters

Selecting the correct spark plug for your 2018 F-250 Super Duty is crucial for maintaining optimal engine performance, fuel economy, and longevity. The spark plug's heat range, or its ability to dissipate heat, must be appropriate for your engine. A plug that is too "hot" can lead to pre-ignition and engine damage, while a "cold" plug can foul and cause misfires.

The electrode material also plays a significant role in a spark plug's performance and lifespan. Iridium and platinum are precious metals that offer superior durability and resistance to wear, making them the standard choice for modern engines like those in your F-250. These plugs can last up to 100,000 miles. Copper plugs, on the other hand, are less expensive but have a much shorter lifespan, typically requiring replacement every 30,000 miles. For your 2018 F-250, it is highly recommended to use iridium or platinum spark plugs to ensure a long service interval and reliable performance.

How to gap a spark plug

Properly gapping your spark plugs is essential for a strong, consistent spark. The gap is the distance between the center and ground electrodes. An incorrect gap can lead to a weak spark, misfires, and reduced fuel efficiency. To gap a spark plug, you will need a feeler gauge or a wire-style gapping tool. Gently insert the tool between the electrodes. If the gap is too narrow, use the tool to carefully bend a new gap into the ground electrode. Be careful not to apply too much pressure or damage the delicate center electrode. Most aftermarket spark plugs come pre-gapped, however, it is always a good idea to double check the gap before installation.

Replacement procedure tips

Both the 6.2L V8 and 6.8L V10 engines in the 2018 F-250 feature a coil-on-plug ignition system, which means each spark plug has its own ignition coil. To access the spark plugs, you will first need to remove the ignition coils. This is a straightforward process that typically involves removing a single bolt and disconnecting the electrical connector.

The debate over using anti-seize on spark plug threads is a long-standing one. While it can help prevent the plugs from seizing in the cylinder head, it can also act as a lubricant, leading to over-torquing. If you do choose to use anti-seize, apply a very small amount to the threads, and be sure to reduce the torque specification by about 10-15%.

It is also a good practice to apply a small amount of dielectric grease to the inside of the spark plug boot before reinstalling the ignition coil. This will help to seal out moisture and prevent corrosion.

Known issues

One of the most well-known issues with Ford modular engines is the tendency for the two-piece spark plugs to break off in the cylinder head during removal. This was a major problem on the earlier 3-valve Triton engines, but it is much less common on the newer engines like those in your 2018 F-250. However, it is still a good idea to be aware of this potential issue and to take your time when removing the spark plugs. If a plug does break, there are special tools available to extract the broken piece.

Another issue to be aware of is the potential for cracked porcelain on the spark plugs. This can be caused by over-torquing, or by using the wrong socket. A cracked porcelain can lead to a misfire and should be replaced immediately.

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