1. N57 Timing Chain Tensioner & Guide Wear(E90 LCI, F30)
Symptoms: Rattling noise from the rear of the engine on cold start, metallic grinding at 2,000 rpm, engine warning light, loss of power.
Typical Mileage: 80,000–150,000 miles
Repair Cost: £1,500–£3,500 (timing chain, tensioner and guide replacement — engine-out or gearbox-off job)
Replacement Cost: £4,500–£8,000 (if chain snaps and valves meet pistons)
Urgency: Immediate — if you hear rattle, book an inspection today
Our recommendation:
The N57's rear-mounted timing chain is the defining weak point of this engine generation. Unlike the front-mounted M57 chain, N57 chain replacement is a labour-intensive job. From 2015 onwards, BMW revised the guides with filled-in ribs to reduce failure rates, but the risk remains. Regular oil changes (10,000 miles max, not BMW's CBS intervals) are the best prevention. At the first sign of rear-engine rattle, get it inspected immediately — a £1,500–£3,500 preventative chain replacement is dramatically cheaper than a £4,500+ engine swap.












