BMW 330d
Successor to the M57 with aluminium crankcase and piezo injectors. Extremely smooth and torquey. EGR cooler, DPF and turbocharger are the main wear points.
Diesel Straight-Six
Beefy diesel R6 — devours motorway miles, but won't stir the soul.
Engine Weaknesses 6
The N57D30 timing chain can break; plastic guide rails break and block the oil pump. Damaged valves and bearing shells follow. No reliable audible advance warning.
Symptoms: Rattling or clattering on cold start (warning sign!). Often no advance warning — engine dies suddenly.
Main bearings and connecting rod bearings wear from around 150,000–200,000 km. The aluminium crankcase with steel bearing housings has differing thermal expansion coefficients. Bearing shells can spin — catastrophic engine damage.
Symptoms: Dull knocking or hammering from the engine block under load; oil pressure warning; metallic tapping; engine oil with metallic particles
Leaking EGR coolers cause gradual coolant loss. BMW carried out a voluntary service campaign. Overheating from coolant shortage risks a cracked cylinder head. Repair costs without goodwill are very high.
Symptoms: Gradual coolant drop with no visible external leak; white-blue exhaust smoke; sweet smell inside the cabin; engine warning light; overheating warning
The N57 bi-turbo system shows bearing wear at high mileage. Broken turbine blades can destroy the cylinder bores and cause total engine failure. Repair costs often exceed €8,000.
Symptoms: Whistling or rattling from the turbo area; sharply reduced power delivery; blue or white exhaust smoke; engine warning light; limp mode
Diesel injectors wear at high mileage. Diagnosis via cylinder balance test and return flow measurement. Individual injector replacement possible at around €450 including installation.
Symptoms: Rough running especially at idle (engine "runs like a tractor"), hesitation, increased fuel consumption, smoke clouds.
Glow plugs and the glow plug control unit fail regularly at higher mileages. The fault memory often shows all plugs as defective even though only the control unit is faulty. Cold-start problems and DPF overload possible in frost.
Symptoms: Glow plug warning light stays on; difficult starting below 5°C; slight judder in the first minute after cold start
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.