BMW 3 Series E90 320d N47 2.0d 177bhp — N47 Timing Chain Failure (Rear of Engine)
The BMW N47 diesel engine has a timing chain positioned at the REAR of the engine, against the bulkhead. Chain failure is catastrophic, and repair requires engine removal. This is the most significant known fault in the BMW 3 Series range.
Severity
CriticalDIY Difficulty
Professional Only
Est. Cost
£2000–£3500
OBD Codes
P0016P0017P0011Timing Chain
Typical layout and location for the Timing Chain assembly.
Symptoms
- Rattling noise from REAR of engine (not front) on cold start
- Noise fades as oil pressure builds but returns on cold mornings
- Timing warning codes: P0016, P0017
- In failure: engine cuts out suddenly, timing jumps, bent valves, total engine destruction
- Average failure mileage: 80,000-140,000
Root Cause
BMW made the cost-saving decision to run the timing chain on the gearbox end of the engine. The chain, guides and tensioner all wear — but access requires removing the engine from the car. Many owners were unaware of the issue until failure occurred.
How To Fix
- Listen for the rattle — it comes from BEHIND the engine, not the front
- If you hear the rattle, stop driving and book in immediately
- Engine must come out for the repair — this is a £2,000-3,500 job at a specialist
- A full chain kit replacement (chain, guides, tensioner, sprockets) is required
- Ask any prospective purchase: 'has the timing chain been done?' — get written proof
- BMW Extended Warranty or SMMT claims have been made on some examples
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £800–£1400 |
| Independent Garage | £2000–£3500 |
| Main Dealership | £3200–£5600 |
Other Faults on This Variant
Swirl Flap Failure and Engine Ingestion
CriticalThe N47 intake manifold has metal swirl flaps on actuator rods. When the rods corrode and snap, the flap breaks off and gets ingested into the engine, causing severe internal damage.
EGR Cooler and Valve Failure
ModerateEGR cooler failure on the N47 is common from 70,000 miles. Coolant leaks into the intake manifold and the EGR valve sticks, causing power loss and rough running.
Excessive Oil Consumption / PCV Valve Failure
ModerateThe N47 engine can consume significant amounts of oil due to a blocked Positive Crankcase Ventilation (PCV) breather, forcing oil past the turbo seals or piston rings.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.