2015 Mercedes-Benz Sprinter Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2015 Mercedes-Benz Sprinter is crucial for optimal engine performance, fuel efficiency, and emissions. There's more to a spark plug than just making a spark; factors like heat range, electrode material, and gap all play a vital role.

Heat Range: This refers to the plug's ability to dissipate heat from the combustion chamber. A plug that's too "cold" won't burn off deposits effectively, leading to fouling. A plug that's too "hot" can cause pre-ignition or detonation, which can severely damage your engine. The OEM specified heat range ensures the plug operates at an optimal temperature.

Electrode Metal: The material of the center and ground electrodes significantly impacts service life and performance.

• Iridium: This is the material of choice for modern, long-life spark plugs, like those specified for the gasoline Sprinter. Iridium is extremely hard and has a very high melting point, allowing for fine-wire electrodes that provide a more robust spark and extended service intervals, typically 100,000 miles or more.
• Platinum: While not as durable as iridium, platinum plugs also offer extended life compared to copper, often lasting 60,000 to 80,000 miles. They are also used in some OEM applications.
• Copper: These plugs have a copper core with a nickel alloy tip. Copper is an excellent conductor of electricity and heat, but it's a softer metal, meaning these plugs wear faster. They are typically found in older vehicles or those with specific performance requirements, and usually require replacement every 30,000 miles or so. Your gasoline Sprinter will not use copper plugs.

Mercedes-Benz Sprinters equipped with diesel engines (OM651 and OM642) do not use spark plugs. Instead, they utilize glow plugs, which are designed to heat the combustion chamber to aid in cold starting. Glow plugs operate differently and have different service intervals and replacement procedures.

How to gap a spark plug

For the 2015 Mercedes-Benz Sprinter with the M272 gasoline engine, gapping is critical. While many iridium plugs come pre-gapped, it's always a good idea to double-check. The correct gap for the 3.5L M272 V6 is 0.039 inches (1.0 mm).

To gap a spark plug, you will typically use a wire-style or coin-style spark plug gap tool. Carefully slide the appropriate thickness gauge between the center and ground electrodes. If the gap is too small, you can gently bend the ground electrode outwards with the tool. If the gap is too wide, you'll need to carefully tap the ground electrode on a hard, non-abrasive surface to close it slightly. Be very careful not to apply too much pressure on the delicate iridium center electrode, as it can easily be damaged.

Replacement procedure tips

Replacing spark plugs on your 2015 Mercedes-Benz Sprinter 3.5L M272 V6 can be a DIY task for the mechanically inclined, but it requires care.

1. Coil-on-Plug (COP) Removal: The M272 engine uses a coil-on-plug ignition system, meaning each spark plug has its own ignition coil mounted directly on top of it. To access the spark plugs, you'll need to carefully disconnect the electrical connector from each coil and then unbolt and remove the coil. Use caution as the connectors can become brittle with age.
2. Cleanliness is Key: Before removing the old plugs, it's a good idea to use compressed air to blow out any debris around the spark plug wells. This prevents dirt and grime from falling into the combustion chamber once the old plug is removed.
3. Anti-Seize Debate: There is ongoing debate about using anti-seize on spark plug threads. Mercedes-Benz generally advises against it for their spark plugs, as many modern plugs feature a special coating on the threads. Using anti-seize can alter the torque readings, potentially leading to over-tightening and damage to the cylinder head threads. Follow the manufacturer's recommendation.
4. Dielectric Grease on Boots: Applying a small amount of dielectric grease inside the spark plug boot (the part that connects to the coil) can help prevent moisture intrusion, voltage leakage, and make future removal easier. Be careful not to get any grease on the electrode tips of the spark plug.
5. Torque is Everything: Always use a torque wrench to tighten the new spark plugs to the specified 18 lb-ft (24 Nm). Over-tightening can strip the threads in the cylinder head or crack the spark plug's porcelain insulator. Under-tightening can lead to compression leaks and the plug backing out.

Known issues

Fortunately, the 2015 Mercedes-Benz Sprinter with the M272 gasoline engine is not commonly associated with widespread, well-known spark plug issues like the infamous broken two-piece spark plugs in some Ford 3-valve engines. The primary concern is simply reaching the end of the service life of the iridium plugs. However, it's always good practice to inspect the old plugs for signs of abnormal wear, oil fouling, or rich/lean conditions, as these can indicate other engine problems.

Need plugs replaced? Find a shop on Repairius.