Mercedes Benz R Class 280 CDI/320 CDI Engine Replacement Compare Prices & Get Quotes

Short summary: A rebuilt OM642 engine for the R 280 CDI or R 320 CDI costs £2,800-£4,600 supply-only. Fitting adds £800-£1,500 depending on complexity - the OM642 V6 requires specialist knowledge for proper installation.

• R 280 CDI / R 320 CDI (OM642.950): rebuilt unit £2,800-£4,600; used engine from £1,500
• OM642 timing chain replacement (labour only): £1,200-£1,900 at specialist
• OM642 oil cooler seal replacement: £950-£1,400 at specialist

Short summary: A rattling noise on cold start between 900-1,200rpm is the classic warning sign on the OM642 engine. If ignored, it can lead to engine seizure and catastrophic failure.

• Cold start rattle that disappears after oil pressure builds - earliest warning
• Check engine light with timing correlation codes
• Metallic swarf in engine oil indicates chain guides wearing away
• Preventative chain replacement costs £1,200-£1,900 at specialist

Short summary: The OM642 V6 is fundamentally robust, but R Class owners should be aware of timing chain stretch between 80,000-120,000 miles, oil cooler seal degradation, and swirl flap failure. With these addressed, the engine is capable of 150,000+ miles.

• OM642 V6 is fundamentally robust with proven durability
• Timing chain stretch is the most critical failure point
• Oil cooler seal degradation affects many units from 90,000 miles
• Well-maintained OM642 engines exceed 150,000 miles

Short summary: Properly maintained OM642 engines routinely reach 150,000-200,000 miles before major work is needed. One owner reported 200,000 km (124,000 miles) with the engine still running.

• OM642 (R 280/320 CDI): 150,000-200,000+ miles with regular servicing
• Timing chain inspection recommended from 80,000 miles
• Service interval is 10,000 miles or 12 months - use Mercedes-spec low-SAPS oil (MB 229.51)
• Late oil changes accelerate timing chain wear and oil cooler seal degradation

Short summary: Yes, if the R Class is otherwise in good condition with no rust or major transmission faults. A rebuilt OM642 costs £2,800-£4,600 - comparable to the value of a £3,000-£8,000 vehicle, making it a justifiable investment for well-maintained examples.

• R 280/320 CDI values: £3,000-£8,000 depending on year, mileage and condition
• Rebuilt engine with upgraded components fixes original weak points
• Supply & fit typically £3,600-£6,100 depending on engine code
• New engine includes 12-month unlimited mileage warranty

Short summary: Mercedes-Benz specifies low-SAPS oil meeting MB 229.51 - typically 5W-30. The OM642 V6 requires approximately 8.5 litres with filter.

• OM642 (R 280/320 CDI): MB 229.51 5W-30 low-SAPS - protects DPF and emissions systems
• Never use non-approved oil - can cause timing chain and injector issues
• Change every 10,000 miles or 12 months - stretched intervals cause timing chain wear