2016 Mercedes-Benz Sprinter Spark Plug Type, Gap & Torque Specifications

As an ASE-certified master technician, I regularly get questions about ignition service on commercial vans. When it comes to the 2016 Mercedes-Benz Sprinter, there is a very important distinction to make right away: the vast majority of 2016 Sprinters sold in North America are powered by diesel engines (the 2.1L inline-4 and 3.0L V6), which use glow plugs, not spark plugs.

However, in global markets (and later introduced to the US fleet), Mercedes offered the Sprinter with a gasoline engine—specifically the 2.0L M274 turbocharged inline-4. If you are operating a petrol-powered 2016 Sprinter, maintaining the ignition system is critical for hauling heavy payloads and maximizing fuel efficiency. Here is everything you need to know about replacing the spark plugs on the gasoline Mercedes-Benz Sprinter.

Quick reference

(Note: If you have a 2.1L OM651 or 3.0L OM642 diesel engine, you require glow plugs, which have completely different specifications and replacement procedures.)

Why the right plug matters

Modern turbocharged, direct-injected engines like the M274 require highly specific ignition characteristics. The heat range of the spark plug is vital; a plug that runs too hot can cause pre-ignition (engine knock) under heavy boost, while a plug that runs too cold will quickly foul with carbon during extended idling.

Mercedes-Benz specifies Iridium-tipped spark plugs for this engine. Iridium is significantly harder and more durable than platinum or traditional copper. This allows for a much finer center electrode, which concentrates the electrical energy to produce a highly efficient spark. This ensures complete combustion, which is necessary to prevent carbon buildup on the direct fuel injectors and intake valves. Never downgrade to copper or standard platinum plugs on a modern turbocharged Mercedes engine.

How to gap a spark plug

The NGK Laser Iridium plugs specified for the 2.0L engine come pre-gapped from the factory at 0.028 inches (0.7 mm). However, as a best practice, you should always verify the gap before installation in case the plug was dropped during shipping.

1. Use the right tool: Use a wire-style feeler gauge rather than a cheap coin-style gauge. Coin gauges can easily snap the brittle iridium center electrode.
2. Measure gently: Pass the 0.028-inch wire between the center and ground electrode. It should pass through with a slight drag.
3. Adjusting the gap: If the gap is too tight, use the bending tool on your wire gauge to slightly pull the ground strap away. If it is too loose, gently tap the ground strap on a soft wooden workbench. Never pry against the iridium center electrode.

Replacement procedure tips

Replacing the spark plugs on the 2.0L M274 is a fairly straightforward coil-on-plug (COP) procedure, but it demands European-specific care:

• Coil-on-plug removal: The ignition coils are bolted down. Remove the retaining bolts and gently twist the coil while pulling upward to break the seal of the rubber boot. If the boots are stuck, do not rip them. Use a specialized boot puller tool if necessary.
• The anti-seize debate: Mercedes-Benz and NGK explicitly advise against using anti-seize compound on these spark plugs. Modern NGK plugs feature a trivalent metal plating that prevents thread seizure. Adding anti-seize alters the friction coefficient of the threads, meaning if you torque the plug to 17 lb-ft, you are actually over-tightening it by up to 20%, which can damage the cylinder head.
• Dielectric grease: Apply a very small dab of dielectric grease to the inside tip of the ignition coil boot before reinstalling. This prevents moisture intrusion and stops the boot from welding itself to the ribbed porcelain of the new spark plug over the next 45,000 miles.

Known issues

While the 2.0L M274 does not suffer from the catastrophic two-piece plug breakage seen in the older Ford 3-valve engines, it does have a quirk regarding plug indexing.

Mercedes-Benz engineered the threading in the cylinder head and the factory spark plugs so that when the plug is torqued to exactly 23 Nm (17 lb-ft), the ground strap is oriented perfectly away from the direct fuel injector. This is called "indexing." Over-torquing or under-torquing the spark plug will leave the ground strap blocking the spray of fuel, which can cause poor idle, misfires, and premature carbon fouling. Always use a calibrated torque wrench!

Need plugs replaced? Find a shop on Repairius.