Mercedes Benz SLK 200 CDI Engine Replacement Compare Prices & Get Quotes

Short summary: A rebuilt OM646 engine for the R171 SLK 200 CDI costs £2,000-£3,200 supply-only; a rebuilt OM651 engine for the R172 SLK 200 CDI costs £2,200-£3,600 supply-only. Fitting adds £800-£1,500 depending on complexity - diesel work requires specialist knowledge.

• SLK 200 CDI (OM646.980): rebuilt unit £2,000-£3,200; used engine from £900
• SLK 200 CDI (OM651.980): rebuilt unit £2,200-£3,600; used engine from £1,000
• OM646 swirl flap actuator replacement: £350-£650 at specialist
• OM651 timing chain tensioner replacement: £1,400-£2,200 at specialist

Short summary: Rough running, loss of power, and check engine lights are the classic warning signs on the OM646 engine. The plastic swirl flap linkages can break, causing the actuator to fail. Vacuum line cracks can also cause similar symptoms.

• Rough idling or hesitation under acceleration
• Loss of power or reduced performance
• Check engine light with intake manifold fault codes
• If caught early, linkage repair costs £200-£400 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.

• 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 £1,400-£2,200 at specialist

Short summary: The OM646 and OM651 diesel engines are fundamentally efficient and robust, but both have known weak points. The OM646's swirl flap actuator and DPF issues are common but manageable, while the OM651's timing chain tensioner requires proactive attention.

• OM646 is reliable but swirl flap and DPF issues are common
• OM651 timing chain tensioner wear is the main concern
• Regular oil changes with correct spec oil are essential for both engines
• Regular motorway driving helps prevent DPF regeneration issues

Short summary: Properly maintained OM646 and OM651 engines routinely reach 150,000-200,000 miles before major work. Timing chain issues on the OM651 typically appear between 70,000-100,000 miles.

• OM646 (SLK 200 CDI): 150,000-200,000 miles with regular servicing
• OM651 (SLK 200 CDI): 150,000-200,000 miles - timing chain inspection from 70k miles
• DPF regeneration issues can occur on short-journey driving patterns
• Service interval is 10,000 miles or 12 months - use Mercedes-spec low-SAPS oil

Short summary: Yes, if the SLK is otherwise in good condition with no rust or major transmission faults. A rebuilt OM646 costs £2,000-£3,200 - far less than replacing a £3,000-£12,000 vehicle. SLK 200 CDI values remain strong for well-maintained examples, making engine replacement a worthwhile investment.

• SLK 200 CDI values: £3,000-£12,000 depending on generation, condition and mileage
• Rebuilt engine with upgraded components fixes original weak points
• Supply & fit typically £2,800-£5,100 depending on engine code
• New engine includes 12-month unlimited mileage warranty