BMW 525i
The 258 hp top version of the N52 is one of the last large high-revving naturally aspirated engines from BMW: a magnesium-aluminium composite block that defines the class through extreme smoothness and a willingness to rev that drivers describe as 'like a sewing machine' — so even and effortless in its climb. Compared to the N54 turbo it sounds cleaner and more natural, without turbo hiss; instead a clear naturally aspirated note that fills out with increasing revs. Cold-start behaviour is impeccable; in daily use it runs nearly maintenance-free. Typical weaknesses: electric water pump (fails without warning, 80,000–150,000 km, preventive replacement recommended), Valvetronic eccentric shaft sensor (fault code, limp mode), VANOS solenoids with sludge build-up. Buying tip: check service history, as missed oil changes can permanently impair VANOS function.
NA Straight-Six Bliss
Last great BMW NA straight-six — deep rumble at idle, magnificent above 5,000 rpm.
Engine Weaknesses 5
The N52 electric water pump is a known wear item. When it fails the engine overheats quickly. Recommended: preventive replacement when any abnormalities appear or from around 100,000 km.
Symptoms: Coolant temperature gauge rises quickly, coolant loss, audible pump malfunction, engine overheating.
The gasket between the oil filter housing and the engine block ages and becomes porous, allowing oil into the coolant. Symptoms resemble a head gasket failure. Early replacement of both seals is recommended.
Symptoms: Oil film on the coolant; discoloured oil filler cap; coolant slightly foamy or brownish; no white exhaust smoke — a key differentiator from head gasket damage
The Valvetronic eccentric shaft sensor fails due to moisture and ageing. Fault code 2A31 is typical. The sensor costs approximately €275; installation requires opening the cam cover.
Symptoms: Rough idle; severe judder with light throttle input; increased fuel consumption (up to +30%); fault code 2A31; engine runs better with the sensor disconnected
The N52 magnesium cam cover has known sealing problems. Oil loss at the cam cover gasket, eccentric shaft sensor, and camshaft adjustment motor are common. Aluminium bolts must not be reused.
Symptoms: Oil loss at the cylinder head, oil smell, visible oil traces at the top of the engine, oil spots on the exhaust manifold.
The N52 VANOS solenoid valves block with oil sludge, particularly with long oil change intervals or short-trip driving. Cleaning is possible; a valve swap often suffices. Improved software from 2007/08.
Symptoms: Rough running; poor throttle response; rpm fluctuations at idle; warning light; camshaft phasing fault code; cold-start misfires
Vehicle Weaknesses 8
E61 Touring has air suspension as standard. Compressor and air bellows fail frequently — repair costs can exceed the vehicle's value. A new system from BMW costs around 700 € in parts alone.
The optional active steering can rotate the steering wheel up to 90 degrees or lock the steering due to AFS control unit faults. Recalibration or control unit replacement (over 1,000 €) required.
On the E61 Touring with optional air suspension, compressor and air bellows fail regularly. Often both sides at the same time. Rear sags, fault message appears.
Rust bubbles form in the seam between the rear window and boot lid. Occurs even on well-maintained garaged vehicles because moisture gets trapped in the hemmed edge.
The iDrive infotainment system overheats due to a failed cooling fan — system no longer starts or runs with limited function. Fan runs continuously and drains the starter battery.
Aluminium front control arms on the E60/E61 are particularly prone to wear. Regular inspection is necessary as wear affects handling and tyre wear.
Valve cover gasket and oil filter housing gasket become porous on older E60s. Oil smell in engine bay and visible oil traces. On the M57N2 diesel, crankcase ventilation often also causes oil burning.
Rubber bushings in the rear integral arms wear from around 120,000 km and produce creaking noises. Worn shock absorbers and axle bearings are typical age-related issues.