Mercedes Benz SLC 220d/250d Engine Replacement Compare Prices & Get Quotes

Short summary: A rebuilt OM651 engine for the SLC 220d or 250d costs £3,200-£4,800 supply-only. Fitting adds £800-£1,200 depending on complexity - diesel work requires specialist knowledge.

• SLC 220d/250d (OM651.921/980): rebuilt unit £3,200-£4,800; used engine from £1,200
• OM651 timing chain replacement: £1,600-£2,400 at specialist
• OM651 injector replacement: £400-£800 at specialist

Short summary: A rattling noise on cold start is the classic warning sign on the OM651 engine. The rear-mounted timing chain tensioner can lose pressure, allowing chain slack and guide wear. If ignored, it can lead to catastrophic engine failure.

• Rattling noise on cold start lasting 1-3 seconds - earliest warning
• Check engine light with timing correlation codes
• Metallic debris in the engine oil (severe cases)
• If caught early, timing chain replacement costs £1,600-£2,400 at specialist

Short summary: Early OM651 engines used Delphi piezo injectors which developed a reputation for rough idle, limp mode, and high-pressure rail faults. These injectors are sensitive to fuel quality and operating conditions.

• Rough idle or limp mode - classic injector failure symptoms
• High-pressure rail fault codes
• Poor fuel economy or hard starting
• If caught early, injector replacement costs £400-£800 at specialist

Short summary: The OM651 is fundamentally reliable - 200,000-300,000 km (124,000-186,000 miles) examples are common. However, it has predictable weak points: timing chain stretch from approximately 75,000 miles (120,000 km), injector failures, EGR clogging, and DPF issues. All are manageable with the right maintenance schedule.

• OM651 is fundamentally robust with strong torque and good economy
• Timing chain stretch is the most critical failure point - early intervention is key
• EGR clogging and DPF issues are common on short-journey vehicles
• Regular oil changes with Mercedes-spec low-SAPS oil are essential

Short summary: Properly maintained OM651 engines routinely reach 150,000-200,000 miles before major work. Timing chain issues typically appear between 75,000-120,000 miles (120,000-200,000 km).

• OM651 (SLC 220d/250d): 150,000-200,000 miles with regular servicing
• Timing chain inspection recommended from 75,000 miles (120,000 km)
• Service interval is 10,000 miles or 12 months - use Mercedes-spec low-SAPS oil
• Late oil changes accelerate timing chain wear and EGR clogging

Short summary: Yes, if the SLC is otherwise in good condition with no rust or major transmission faults. A rebuilt OM651 costs £3,200-£4,800 - far less than replacing a £12,000-£25,000 vehicle. SLC values remain strong for well-maintained examples, making engine replacement a worthwhile investment.

• SLC 220d/250d values: £12,000-£25,000 depending on condition and mileage
• Rebuilt engine with upgraded components fixes original weak points
• Supply & fit typically £4,000-£6,000 depending on engine code
• New engine includes 12-month unlimited mileage warranty