BMW 3 Series E90 320d N47 2.0d 177bhp — Suspension Coil Spring Snapping
A very common MOT failure in the UK. Suspension coil springs corrode and snap, usually near the bottom pigtail.
Severity
SevereDIY Difficulty
Hard
Est. Cost
£150–£300
OBD Codes
None
Suspension
Typical layout and location for the Suspension assembly.
Symptoms
- Loud 'twang' or bang when turning the steering wheel at low speeds
- Car sits noticeably lower on one side
- Grating noise over bumps
Root Cause
The protective coating on the steel spring chips from stone impacts. Salt water corrodes the exposed steel, weakening the spring until it fractures under load.
How To Fix
- Visually inspect all four springs for fractures at the very bottom coil.
- Always replace coil springs in pairs across an axle to maintain handling balance.
- Cost: £150-300 per pair at an independent garage.
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £60–£120 |
| Independent Garage | £150–£300 |
| Main Dealership | £240–£480 |
Other Faults on This Variant
N47 Timing Chain Failure (Rear of Engine)
CriticalThe 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.
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.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.