Mercedes-Benz E-Class W212 E220 CDI — Timing Chain Stretch (Rear Mounted)
Like BMW's N47, Mercedes placed the OM651's timing chain at the rear of the engine. It is a single-row chain that stretches over time, causing a loud rattle on cold starts.
Severity
CriticalDIY Difficulty
Professional Only
Est. Cost
£1200–£2000
OBD Codes
P0016Timing Chain
Typical layout and location for the Timing Chain assembly.
Symptoms
- Loud metallic rattle on cold start lasting 3-4 seconds
- EML light with camshaft correlation faults
- Rattle disappears when warm
Root Cause
The single-row simplex chain wears and stretches. The hydraulic tensioner takes a few seconds to build oil pressure on cold start, allowing the loose chain to rattle against the guides.
How To Fix
- The engine MUST be removed to replace the timing chain.
- Mercedes later introduced an upgraded tensioner to mitigate the issue, but a stretched chain still requires full replacement.
- Change oil every 10k miles minimum to extend chain life.
- Cost: £1,200 - £2,000
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £480–£800 |
| Independent Garage | £1200–£2000 |
| Main Dealership | £1920–£3200 |
Other Faults on This Variant
Air Conditioning Condenser Leak (Stone Damage)
MinorThe air conditioning condenser is mounted at the very front of the cooling pack, making it highly susceptible to stone damage from the road, leading to refrigerant loss.
Front Anti-Roll Bar Drop Link Wear
MinorThe front anti-roll bar drop links wear out on heavily potholed UK roads, causing an annoying knocking sound at low speeds.
Alternator / Smart Charge System Failure
SevereModern vehicles use smart charging systems to reduce engine load, but the complex regulators on the alternators frequently fail.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.