BMW 325i
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.
Rewarding at Every Rev
NA six-cylinder with genuine character — equally brilliant in estate or coupe form.
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 7
Faulty battery connectors on petrol models 2006–2011 and diesels 2009–2011 can cause complete electrical and engine failure. Recall was issued.
The electromechanical power steering (EPS) can fail sporadically without any fault codes — often due to corroded connectors or an overheated EPS motor. KBA recall for production years 2007–2012.
Rear suspension springs break frequently — a well-known MOT failure point. Especially E91 Touring and older examples from around 100,000 km. Spring seats also rust.
Water ingress through leaking door seals, blocked sunroof drain tubes, or faulty antenna brackets. Battery compartment and footwell can both be affected. Multiple causes.
Underbody, wheel arches, and rear subframe rust commonly reported on the E91 Touring. Door seal frames corrode on older examples; tailgate particularly susceptible.
Control arm bushings and joints wear from around 100,000 km. Aluminium wishbones on the front axle are a typical wear item. Full arm from 200 €, bushings from 10–50 € each.
The acoustic foam in the doors separates from the butyl seal and lets rainwater into the footwell. Damp floor mats and rotting carpet result.