2024 Kenworth T680 Spark Plug Type & Gap

Quick reference

Why the right plug matters

The Kenworth T680, a workhorse in the trucking industry, primarily utilizes diesel engines. Diesel engines operate on a compression-ignition principle and do not use spark plugs in the same way gasoline engines do. Therefore, discussions about spark plug types, gaps, and replacement procedures are not applicable to the standard diesel-powered 2024 Kenworth T680.

However, in a hypothetical scenario where a gasoline engine variant existed, the right spark plug would be crucial for optimal performance, fuel efficiency, and emissions. Here's why:

• Heat Range: Spark plugs are designed with a specific "heat range" – their ability to dissipate heat from the combustion chamber. A plug that's too "cold" (dissipates too much heat) can lead to carbon fouling, while a plug that's too "hot" (doesn't dissipate enough heat) can cause pre-ignition or engine knock. Matching the correct heat range is vital for long engine life and efficient combustion.

• Electrode Metal: The material of the spark plug's electrodes significantly impacts its lifespan and performance.

  • Iridium: The most durable and expensive, iridium plugs offer the longest lifespan and consistent, powerful sparks due to their extremely fine electrodes.
  • Platinum: Platinum plugs provide excellent durability and performance, often lasting longer than copper plugs. They are a good balance of cost and longevity.
  • Copper: While offering excellent conductivity and a strong spark, copper plugs have the shortest lifespan due to the softer nature of the metal, requiring more frequent replacement.

How to gap a spark plug

While not applicable to the diesel 2024 Kenworth T680, for a gasoline engine, properly gapping a spark plug is essential. The gap is the distance between the center and ground electrodes. Incorrect gapping can lead to misfires, reduced fuel efficiency, and increased emissions.

1. Obtain the correct gap specification: Always refer to the manufacturer's specifications (if this were a gasoline engine).
2. Use a gapping tool: A wire-type feeler gauge is ideal for accurately measuring the gap without damaging the delicate electrode. Avoid using coin-style gappers, as they can bend the center electrode.
3. Adjust carefully: If the gap is too small, gently widen it by prying up the ground electrode with the gapping tool. If it's too wide, carefully tap the ground electrode on a hard surface to close the gap. Always adjust the ground electrode only, never the center electrode.
4. Re-check the gap: Verify the gap after every adjustment to ensure accuracy.

Replacement procedure tips

Again, these tips are for a hypothetical gasoline engine in a 2024 Kenworth T680, as the diesel engines do not use spark plugs.

• Coil-on-Plug Removal: Most modern gasoline engines use a coil-on-plug (COP) ignition system. To remove the spark plugs, you would first disconnect the electrical connector from each coil and then remove the coil pack, which is typically secured by a single bolt.
• Anti-seize Debate: While some technicians apply a small amount of anti-seize to spark plug threads, many spark plug manufacturers advise against it, especially with nickel-plated plugs. The anti-seize can act as an electrical insulator and affect torque readings, potentially leading to over-tightening.
• Dielectric Grease on Boots: Apply a small amount of dielectric grease to the inside of the spark plug boot (the end that connects to the spark plug). This helps seal out moisture, prevents corrosion, and makes future removal easier.
• One at a Time: To avoid mixing up coils or getting debris into open spark plug wells, replace plugs one at a time.

Known issues

Since the 2024 Kenworth T680 is equipped with diesel engines (PACCAR MX-13 or Cummins X15), there are no known spark plug specific issues like those found in gasoline engines (e.g., Ford 3-valve 2-piece plug breakage or GM 5.3 ionization-sensing coils).

Need plugs replaced? Find a shop on Repairius.