The N52 | BMW's Last Naturally Aspirated Engine
When BMW built the N52, they didn't just create another inline-six; they ended the legacy of their Naturally Aspirated inline-6 engines. Produced from 2004 to 2015, the N52 was the final NA engine from BMW before the shift to turbocharging. It wasn’t just another six-cylinder—it was a benchmark in engineering, blending lightweight materials, innovative tech, and reliability in a way that enthusiasts still admire today. Here’s why the N52 remains a favorite among Bimmer purists.
Engineering Excellence: The Most Reliable BMW Inline-Six?
BMW pushed boundaries with the N52, introducing the first water-cooled engine with a magnesium-aluminum composite block. The goal? A lighter engine without compromising durability. Magnesium, while strong, is prone to corrosion, so BMW engineered an aluminum core wrapped in a magnesium shell. The result was a groundbreaking design that kept weight down while maintaining the robustness expected from a BMW inline-six.
Paired with Valvetronic variable valve lift, an electric water pump, and a variable output oil pump, the N52 was leagues ahead of its predecessor, the M54. It also retained key features like BMW’s twin VANOS system and electronic throttle control, refining performance and efficiency.
N52 Variants: Two Displacements, Multiple Power Levels
BMW offered the N52 in two sizes:
2.5L (N52B25)
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Produced from 2005 to 2011
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Power output ranged from 174 to 215 hp
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Torque varied between 170 and 184 lb-ft
3.0L (N52B30)
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Produced from 2006 to 2015
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Power output ranged from 215 to 268 hp
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Torque varied between 199 and 232 lb-ft
All versions had an 85mm bore, 88mm stroke, and a 10.7:1 compression ratio, with differences in ECU tuning and intake manifolds influencing final performance.
Which BMWs Came with the N52?
The N52 powered a wide range of BMWs across multiple series:
N52B25 (2.5L)
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E90 323i
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E60/E61 523i
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F10 523i
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E83 X3 2.5si
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Various Z4 models
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E90/E91/E92/E93 325i & 325xi (not sold in the U.S. or Canada)
N52B30 (3.0L)
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E90/E92/E93 325i & 325xi
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E60/E61 525i & 525xi
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F01 730i
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E87 130i
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E83 X3, E70 X5, and E63/E64 630i (2006-2013)
With 268 hp, the most powerful N52 variant remains the strongest naturally aspirated inline-six ever fitted to a non-M BMW.
Common N52 Problems: What to Watch Out For
Even the best engines have weak spots, and the N52 is no exception. While known for its reliability, certain issues are common:
Ignition Coil Issues
Faulty ignition coils are a well-known problem. Often, they fail due to worn spark plugs, forcing the coils to work harder. Using high-quality coils and regularly replacing spark plugs can prevent premature failure.
Water Pump Failures
Unlike the mechanical pumps in older BMWs, the N52 uses an electric water pump—great for efficiency but prone to failure as early as 40,000 miles. Symptoms include overheating and vapor from the radiator. Many owners opt for a metal impeller upgrade when replacing the pump.
VANOS Solenoid Failures
The twin VANOS system is key to the N52’s performance, but its solenoids can fail, leading to rough idle, power loss, and sluggish throttle response. Fortunately, replacing them is relatively simple and inexpensive.
Hydraulic Valve Lifter Tick
A distinctive ticking noise, especially at cold starts, is common in pre-2009 N52 engines. This comes from worn hydraulic valve lifters due to poor lubrication in early cylinder head designs. BMW revised the design in 2009, but some post-2009 models still report the issue.
Valve Cover Gasket & Oil Filter Housing Leaks
Both the valve cover gasket and oil filter housing gasket degrade over time, leading to oil leaks. If left unchecked, leaks from the oil filter housing can allow oil to drip onto the serpentine belt, potentially causing catastrophic engine damage.
Why the N52 Still Matters
Despite these common problems, the N52 remains one of BMW’s best-engineered inline-sixes. Its naturally aspirated power delivery, lightweight construction, and smooth revving nature make it a favorite among enthusiasts. Whether you’re daily driving, modifying, or restoring a classic BMW, the N52 is an engine worth appreciating—and preserving.