BMW 730d

As mileage increases the timing chain stretches and the chain tensioner loses its spring force. Broken plastic guide rails send fragments into the oil sump, which can damage the oil pump.

Symptoms: Rattling or clattering on cold start that improves once warm. Engine warning light.

The turbocharger wears through bearing problems or insufficient lubrication. Particularly at risk with infrequent oil changes or immediate shutdown after full-load driving.

Symptoms: Whistling noises, significant power loss, blue exhaust smoke, oil in the intercooler.

The plastic swirl flaps in the intake manifold break off and can be ingested by the engine. M57 engines built before 03/2004 are particularly at risk — complete removal is widely recommended.

Symptoms: Hesitation at low rpm; power loss; rattling from the intake area; in the worst case engine damage from ingested flaps; no fault code in early stages

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, white/black smoke.

The M57 EGR valve becomes coked at high mileage. On the M57 cleaning can be done with the valve in situ — an advantage over newer engines. Regular cleaning every 60,000–80,000 km is recommended.

Symptoms: Sluggish throttle response; black smoke under acceleration; rough idle; power loss especially at low rpm

Sills and wheel arches rust heavily, especially on older examples. Fuel tank tray and brake lines under the floor are also at risk.

The plastic upper coolant hose fitting on the radiator breaks due to material fatigue at high operating temperatures.

Early production vehicles (1994–1996) have a manufacturing defect: cables in the front right wing chafe against the body. BMW marked repaired vehicles with a red dot.

Rear trailing arm bushings wear out. BMW only sells the complete arm. Polybushings as an alternative.

The crankcase ventilation membrane becomes porous and leads to heavy oil consumption. V8 engines M60/M62 affected.