2009 — 2013
3.0L M57T2 Twin-Turbo Diesel (335d) - M Sport/SE trim
Diesel
Check this by accelerating firmly on an open road, listening for any excessive hissing or whining sounds. | Description: It is quite common for the boost hoses or the intercooler seals to develop small leaks over time, which can impact the efficiency of that impressive twin-turbo setup.
While driving at low speeds, gently apply the brakes and feel for any shuddering through the steering wheel. | Description: The E90 platform is known for its heavy front end, and it is worth noting that lower control arm bushings can wear out, leading to vibrations during braking or uneven tyre wear.
Check this by performing a cold start and watching for any blue or heavy white smoke from the exhaust. | Description: While the M57 engine is a legendary unit, it is sensible to look for signs of oil consumption or issues with the diesel particulate filter (DPF) that may have arisen due to short-trip driving patterns.
Check this by turning the steering wheel fully to lock while stationary and listening for any groaning sounds. | Description: The power steering pump and rack can eventually show their age; it is a good idea to ensure the steering feels smooth and consistent throughout the entire range of motion.
Usually the time to inspect the condition of the vacuum lines controlling the turbo actuators, as these can become brittle.
Often when the glow plug control module may require a check, as these are known to be a common wear item in cooler climates.
Consider having the condition of the harmonic balancer inspected, as this is a vital component for engine longevity.
Prioritise regular engine oil changes every 10,000km using high-quality fully synthetic oil to protect the turbochargers.
Keep an eye on the transmission fluid; while often listed as 'sealed for life', a fluid and filter change can help maintain smooth shifts.
Regularly clean the water drainage channels under the bonnet to prevent water ingress into the cabin air filter or ECU housing.
Ensure the DPF is allowed to perform its regeneration cycle by occasionally taking the car for a longer highway drive.
Check the coolant hoses for any signs of hardening or cracking, as these are critical to preventing overheating in these engines.
Estimated repair costs if issues arise
If the boost pressure becomes inconsistent, you might eventually need to budget for the replacement of vacuum lines or the electronic turbo actuators to regain that signature 335d power.
Given the nature of diesel engines, carbon buildup can accumulate in the intake ports over many years; a professional walnut blasting service can help restore performance and throttle response.
To keep the handling sharp and the ride compliant, you might eventually need to budget for a refresh of the front suspension components as they do absorb significant stress over time.
As part of long-term reliability planning, it is often wise to consider these components if they haven't been documented as replaced, as they are crucial for maintaining optimal operating temperatures.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer