BMW 5 Series E60 520d N47 2.0d 177bhp — Cooling System Thermostat Housing Failure
The plastic thermostat housing on the N47 is notorious for cracking and causing coolant loss. BMW used plastic for this component in a bid to save weight — it fails prematurely.
Severity
ModerateDIY Difficulty
Moderate
Est. Cost
£200–£400
OBD Codes
P0128P0217Cooling
Typical layout and location for the Cooling assembly.
Symptoms
- Coolant loss without external leak under engine
- Overheating warning light
- Coolant puddle under car after a run
- Temperature gauge climbing above normal
Root Cause
The plastic housing is stressed by repeated thermal cycling. Hairline cracks develop at the sealing faces, allowing coolant to leak. Failures become more common from 70,000 miles.
How To Fix
- Replace thermostat housing with the updated part (some have been revised)
- Replace thermostat at the same time
- Bleed cooling system carefully after refill
- Cost: £200-400 fitted at BMW specialist
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 Rear Timing Chain Failure
CriticalThe E60 5 Series with the N47 diesel engine carries the same catastrophic rear-mounted timing chain risk as the E90 3 Series. Engine removal is required for repair — making this one of the most expensive known faults in the BMW range.
Swirl Flap Failure and Engine Ingestion
CriticalThe N47 in the E60 5 Series shares the swirl flap failure risk of all N47-engined BMWs. The flap breaks off the corroded actuator rod and is ingested into the engine.
EGR Failure and Coolant Loss
ModerateEGR cooler failure on the E60 520d N47 causes internal coolant leaks into the intake manifold. Combined with EGR valve carbonising, both components typically need replacing together.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.