N47 Timing Chain Failure
SeriousEngineThe rear-mounted N47 timing chain can stretch and fail with little warning, making it the main risk on 18d and 20d X1s. Access is poor, so even preventive work is expensive.
Most affected: sDrive18d, xDrive18d, sDrive20d, xDrive20d
Typical symptoms
- •Metallic rattle from the gearbox side on cold start
- •Long cranking or timing-related fault codes
- •Sudden loss of drive if the chain jumps
What to inspect before you buy
- ✓Start the engine from fully cold and listen from the cabin and scuttle area
- ✓Ask for invoices covering chain, guides, and tensioners rather than vague reassurance
- ✓Be wary of cars serviced only on long BMW condition-based intervals