Lewis O'Neill
2024-10-20T02:00:00+01:00

Discover the BMW 335i F30/F31 maintenance guide tailored for 2012-2015 models with the N55 engine. Learn about recommended service intervals, common issues like charge pipe failures and carbon buildup, and essential tips for stock and modified vehicles. Keep your 335i running smoothly with expert advice on oil changes, spark plugs, coolant, and more.
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BMW 335i F30/F31 Maintenance Guide (N55)

The BMW 335i, produced between 2012 and 2015, is a popular choice for enthusiasts due to its combination of performance and practicality. Equipped with the robust N55 engine, this car delivers impressive power while remaining relatively reliable if maintained properly. This guide provides an overview of the maintenance requirements for the BMW 335i F30/F31 and offers tips for owners with stock or modified vehicles.

Service Intervals for the 335i (N55)

BMW recommends regular maintenance to ensure optimal performance and longevity. The general service intervals for the 335i with the N55 engine are as follows:

Oil Change: BMW suggests oil changes every 10,000 miles (16,000km) or 12 months, whichever comes first. However, for owners driving aggressively or with modifications, a shorter interval of 5,000 to 7,000 miles (12,000km) is recommended.

Brake Fluid: Replace the brake fluid every 2 years. This is critical for maintaining braking performance, especially during spirited driving. Consider upgrading to a superior brake fluid such as Castrol RBF600 or Castrol RBF660

Air Filter: Replace the air filter every 30,000 miles (45,000km), but inspect it more frequently if driving in dusty conditions. JXL Performance recommends upgrading to a performance drop in filter such as the K&N Performance Replacement Air Filter

Spark Plugs: BMW recommends replacing spark plugs every 60,000 miles. For modified vehicles or those with higher boost levels, consider replacing them every 30,000 to 40,000 miles, or even sooner if the car is used hard/on track. Shop Genuine BMW Spark Plugs here

Coolant: Replace the coolant every 4 years or 60,000 miles. Always use BMW-approved coolant to prevent corrosion and maintain cooling efficiency.

Transmission Fluid: For automatic transmissions, BMW does not specify a change interval, but replacing the fluid every 40,000 to 60,000 miles (65,000km - 96,000km) is advised. Manual transmissions should also have their fluid replaced within this range too.

Belts and Pulleys: Inspect the serpentine belt every 30,000 miles for wear or cracks, and replace as needed.

N55-Specific Maintenance Tips

The N55 engine is known for its reliability, but it has specific areas that require attention:

Oil Quality: Always use high-quality synthetic oil with the appropriate BMW specification. This is crucial for the health of the turbocharger and the engine. Shop BMW specification oil here

Charge Pipe: The factory charge pipe is a known weak point on the N55 engine. Upgrading to an aftermarket aluminum charge pipe is recommended, especially if the vehicle is modified. The stock plastic pipe can crack under higher boost pressures. JXL Performance recommends the MMX Charge Pipe

Valve Cover and Gasket: The valve cover and its gasket are prone to leaks over time. Inspect for oil leaks around the valve cover, particularly near the rear of the engine.

High-Pressure Fuel Pump (HPFP): The HPFP is an essential component for direct injection engines like the N55. While generally reliable, it can fail. Symptoms include long cranking or a loss of power. Regular fuel system cleaning can help maintain its efficiency. Some owners have upgraded to the B58TU fuel pump (from the Toyota Supra).

Ignition Coils: These are another common failure point. If experiencing misfires, replacing all ignition coils along with the spark plugs is recommended. JXL Performance recommends the MMX High Performance Ignition Coilpacks for N55

Water Pump and Thermostat: The electric water pump on the N55 is a known failure point. Replacing it preemptively around 80,000 miles can help avoid overheating issues.

Carbon Buildup: Direct injection engines like the N55 are prone to carbon buildup on the intake valves. Walnut blasting every 60,000 to 80,000 miles can restore performance and efficiency.

Turbocharger: Inspect the turbocharger for signs of wear, such as excessive smoking or reduced boost pressure. Regular oil changes and proper cooldown periods after spirited driving help prolong turbo life.

Tips for Modified 335i Owners

If your 335i is modified, additional care is required to maintain reliability. Ensure that supporting modifications, such as an upgraded intercooler or oil cooler, are installed to manage the increased stress on the engine. Monitor data such as oil temperatures and boost levels regularly. Custom tuning should always be performed by a reputable professional to avoid excessive strain on engine components.

Proper maintenance is essential for ensuring the longevity and performance of your 335i. Following BMW’s service recommendations and addressing the known weak points of the N55 engine can help you enjoy your car for years to come. Whether your car is stock or modified, staying proactive with maintenance is the key to keeping it running smoothly.