BMW 3 Series E90 320d N47 2.0d 177bhp — Shock Absorber Oil Leak and Failure
Shock absorbers lose their damping efficiency over time, and eventually blow their seals, leaking hydraulic fluid.
Severity
ModerateDIY Difficulty
Moderate
Est. Cost
£200–£400
OBD Codes
None
Suspension
Typical layout and location for the Suspension assembly.
Symptoms
- Car bounces multiple times after hitting a bump
- Visibly wet, oily residue running down the outside of the shock absorber body
- Increased body roll in corners and longer braking distances
Root Cause
The internal rubber seals wear out from millions of oscillations. Grit on the damper shaft accelerates the wear, tearing the seal.
How To Fix
- Perform a 'bounce test' on each corner of the car — it should settle immediately after one rebound.
- Replace dampers in axle pairs.
- Consider replacing top mounts and bump stops simultaneously to save on future labour.
- Cost: £200-400 per pair.
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £80–£160 |
| Independent Garage | £200–£400 |
| Main Dealership | £320–£640 |
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.