Parts Guide
BMW ALL PARTS GUIDES

BMW Parts Guides

Part numbers, fitment and common faults for BMW models — organised by model below.

The Older N47/N20 Timing Chain Saga — Context Worth Knowing Even on Newer Cars

If you've researched BMW reliability at all, you've likely encountered the N47 diesel and N20 petrol timing chain reputation — it's genuinely one of the most discussed BMW issues online, and understanding it properly helps put newer engines in context. The N47 diesel (roughly 2006-2015, fitted across the 1, 3, and 5 Series) has a well-documented history of timing chain failure, made worse by the chain's position at the rear of the engine — against the firewall — which makes replacement considerably more labour-intensive and expensive than on engines with a front-mounted chain. The N20 turbocharged petrol (2011-2017) suffered a related but distinct problem: a genuine material defect in the timing chain guides on units built before February 2015, serious enough that BMW issued a formal recall to inspect and replace affected guides. Both were addressed by BMW's B-series successor engines (B47 diesel, B48/B58 petrol) introduced from around 2014-2015 onward, which most of this site's current-generation coverage (G20 3 Series, F40 1 Series, G01 X3, and later) is built around — so this specific legacy issue is largely, though not entirely, behind BMW at the generations covered here.

Newer B-Series Engines: Coolant System Plastics Are the More Relevant Modern Concern

For the current-generation BMWs actually covered on this site, the more relevant recurring theme is coolant system reliability rather than the timing chain — a genuinely different issue, and one owners and specialists discuss constantly across B46, B48, and B58-engined cars. These engines use multiple plastic housings, quick-connect fittings, and cooling modules that age and heat-cycle over time, and owners commonly report coolant loss tracing back to seals or plastic housings around the oil filter housing and oil cooler assembly — areas that are genuinely difficult to inspect without partially stripping the engine down. Watch for a low coolant warning, a sweet smell after driving, dried residue around the filter housing, or needing to top up coolant with no visible puddle underneath the car — all worth investigating promptly, since a slow coolant leak ignored for too long risks head gasket damage.

Even the improved B47 diesel isn't entirely free of its predecessor's concerns — pre-2018 units remain somewhat susceptible to timing chain tensioner wear, producing the same characteristic rattle on cold start, though considerably less prevalent than on the older N47. Many independent BMW specialists recommend a timing chain inspection around 80,000 miles on B47-engined cars as a sensible precaution.

Oil Change Discipline Matters More on BMW Than Almost Any Other Make

Across every engine generation discussed here, one theme repeats constantly in owner and specialist advice: sticking to BMW's official long service interval (commonly up to 18,000 miles) is widely considered too infrequent for genuinely trouble-free ownership, particularly for timing chain longevity. Independent specialists consistently recommend changing oil every 5,000-9,000 miles with correct BMW Longlife-rated synthetic oil regardless of what the service computer suggests — several long-term owners specifically credit this shorter interval with avoiding the chain and internal wear issues that catch out cars serviced strictly to BMW's own schedule. If you're buying a used BMW of any generation, service history showing more frequent oil changes than the official minimum is a genuinely positive sign, not an unnecessary expense on the previous owner's part.

Six-Cylinder Diesels Have a Notably Stronger Reputation Than Four-Cylinder Equivalents

Worth knowing if you're choosing between engine sizes: BMW's six-cylinder diesels (the earlier N57, and by extension the smoother-running character they're known for) have a consistently better reliability reputation among long-term BMW owners than the equivalent four-cylinder diesels of the same era, partly because the six-cylinder design puts less individual strain on shared components. If reliability and refinement matter more to you than outright economy, a six-cylinder diesel BMW of a given generation is often the more dependable choice over its four-cylinder sibling, at some cost to fuel economy.

Find Your Part Fast

Each guide covers a specific part on a specific model, with fitment notes across generations, known failure symptoms, and honest advice on OEM versus aftermarket options.

BMW 3 Series

BMW 1 Series

BMW 2 Series

BMW 4 Series

BMW 5 Series

BMW X1

BMW X3

BMW X5

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