Mercedes Benz SLC 220d/250d Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz SLC 220d and 250d engine specialists. Compare prices on reconditioned, rebuilt and used engines for the 2.1-litre OM651 twin-turbo diesel - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £2,700 to £4,800
Used from £1,200 · Reconditioned from £2,700 · Common codes: OM651.921, OM651.980
From £1,200
Tested, bare/short engine
From £2,700
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz SLC 220d/250d Replacement Engineto Finding the Best Mercedes Benz SLC 220d/250d Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz SLC 220d/250d - Engine History & Specs at a Glance
The SLC 220d and SLC 250d launched with the R172 facelift in 2016 as the diesel options in the SLC range, powered by the OM651 2.1-litre twin-turbo four-cylinder diesel - a refined, torquey unit that offered excellent fuel economy and relaxed cruising. The SLC 250d produced 204hp and 500Nm of torque, making it the most powerful diesel SLC ever offered. Production continued until 2020 when the SLC was discontinued, making these models the final chapter of Mercedes' compact roadster lineage.
Variant HistoryMercedes Benz SLC 220d/250d - Engine History & Specs at a Glance
The SLC 220d and SLC 250d launched with the R172 facelift in 2016 as the diesel options in the SLC range, powered by the OM651 2.1-litre twin-turbo four-cylinder diesel - a refined, torquey unit that offered excellent fuel economy and relaxed cruising. The SLC 250d produced 204hp and 500Nm of torque, making it the most powerful diesel SLC ever offered. Production continued until 2020 when the SLC was discontinued, making these models the final chapter of Mercedes' compact roadster lineage.
Mercedes Benz SLC 220d/250d
Fuel TypeDiesel (twin-turbo common-rail four-cylinder)
Engine Size2.1L (2,143cc)
Power Output Range170-204hp across the variant's historyEngine History Timeline
OM651.921 2.1L twin-turbo diesel, 170hp @ 4,200rpm (SLC 220d, R172 facelift launch)
OM651.921 / OM651.980 2.1L twin-turbo diesel, 204hp @ 4,200rpm, 500Nm @ 1,600rpm (SLC 250d, R172 facelift launch)
2020 - Both engines continue with 9G-TRONIC automatic transmission
End of SLC production; R172 platform retired
Key Specs Snapshot
Fuel TypeDiesel (twin-turbo common-rail four-cylinder)Engine Size2.1L (2,143cc)Power Output Range170-204hp across the variant's historyYears Produced2016-2020Every engine fitted to the Mercedes Benz SLC 220d and 250d is covered below, with UK rebuilt pricing and known failure points - from OM651 timing chain stretch to EGR clogging and injector failures.
Mercedes Benz SLC 220d/250d Engine Codes - Specifications & Replacement CostMercedes Benz SLC 220d/250d Engine Codes - Specifications & Replacement Cost
2.1L Twin-Turbo Diesel (2016-2020)
Power Output170 hp (125 kW) @ 4,200 rpm (SLC 220d); 204 hp (150 kW) @ 4,200 rpm (SLC 250d)Torque400 Nm (295 lb-ft) @ 1,600 rpm (SLC 220d); 500 Nm (369 lb-ft) @ 1,600 rpm (SLC 250d)Years Fitted2016-2020Displacement2,143 cc (131 cui)CylindersInline 4, DOHC, 16-valve, twin-turbocharged with common-rail injectionEngine CodesOM 651.921 (220d / 250d), OM 651.980 (250d)
Compatible Trim Levels
- SLC 220d
- SLC 220d AMG Line
- SLC 220d Sport
- SLC 250d
- SLC 250d AMG Line
- SLC 250d Sport
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,200-£2,200
Reconditioned
Addressed known issues, tested
£2,700-£3,800
Rebuilt
Full teardown, upgraded internals
£3,200-£4,800
Common Failure
Timing chain stretch and guide wear - the OM651's single most critical failure point. The timing chain drives both camshafts and the high-pressure fuel pump. If it stretches beyond tolerance or a guide fails, the consequences range from misfires and cam/crank correlation codes to catastrophic engine damage if the chain jumps a tooth. Typical failure mileage: 75,000-120,000 miles (120,000-200,000 km). EGR valve clogging and injector failures are also common.
The SLC 220d and 250d's OM651 twin-turbo diesel is fundamentally reliable - 200,000-300,000 km (124,000-186,000 miles) examples are common - but has predictable weak points: timing chain stretch from approximately 75,000 miles (120,000 km), early injector failures, EGR clogging, and water pump leaks. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing these original failure points, plus a minimum 12-month unlimited-mileage warranty.
The Most Critical Diesel Failure
Affected Vehicles
Mercedes SLC 220d, SLC 250d (OM651.921 / OM651.980, 2016-2020)
Typical Failure Mileage
75,000-120,000 miles (120,000-200,000 km)
Root Cause
The OM651's timing chain drives both camshafts and the high-pressure fuel pump. A hydraulic tensioner can lose pressure prematurely, allowing chain stretch and guide wear. If the chain jumps a tooth, the consequences range from misfires and cam/crank correlation codes to catastrophic engine damage. Cold-start rattling is the classic warning sign.
Why It Happens
The OM651's timing chain drives both camshafts and the high-pressure fuel pump. A hydraulic tensioner can lose pressure prematurely, allowing chain stretch and guide wear. If the chain jumps a tooth, the consequences range from misfires and cam/crank correlation codes to catastrophic engine damage. Cold-start rattling is the classic warning sign.
Dealer (parts + labour)
£200-£400
Specialist (parts + labour)
£150-£300
What it involves
Timing chain inspection, camshaft correlation check, oil pressure test
Suitability
First step - confirms whether chain or tensioner is the issue
1 - 2 daysDealer (parts + labour)
£2,500-£4,000
Specialist (parts + labour)
£1,600-£2,400
What it involves
Replace timing chain, guides, tensioner, inspect oil pump chain
Suitability
If caught before chain stretch is severe
1 - 2 daysDealer (parts + labour)
£5,000-£7,000
Specialist (parts + labour)
£3,200-£4,800
What it involves
Complete engine swap with upgraded timing components, 12-month warranty
Suitability
If timing failure has caused valve damage
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Diagnostics - Timing chain inspection Minor | £200-£400 | £150-£300 | Timing chain inspection, camshaft correlation check, oil pressure test | First step - confirms whether chain or tensioner is the issue | 1 - 2 days |
 Intermediate - Timing chain & tensioner replacement Best Value | £2,500-£4,000 | £1,600-£2,400 | Replace timing chain, guides, tensioner, inspect oil pump chain | If caught before chain stretch is severe | 1 - 2 days |
Full Replacement - Rebuilt OM651 engine Best Value | £5,000-£7,000 | £3,200-£4,800 | Complete engine swap with upgraded timing components, 12-month warranty | If timing failure has caused valve damage | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 2016-2020 SLC 220d or 250d is worth approximately £12,000-£25,000 depending on mileage and condition. These premium roadsters retain strong values for well-maintained examples, making engine replacement a justifiable investment.
Our Recommendation
Our Recommendation
If your SLC 220d or 250d exhibits a rattling noise on cold start, act immediately. The OM651's timing chain is a known critical weakness. Specialist timing chain replacement at £1,600-£2,400 is significantly cheaper than dealer rates. If the chain has jumped timing, a full rebuilt OM651 engine with upgraded tensioner components is the only safe option.
Don't Let Timing Chain Stretch, Injector Failure, or DPF Issues Write Off Your Mercedes SLC 220d or 250d
Whether you're facing OM651 timing chain stretch on your SLC 220d, injector failures on your SLC 250d, or DPF regeneration issues, EnginesMarket makes it simple to compare quotes from trusted UK Mercedes diesel specialists. Every rebuilt engine in our network carries upgraded components addressing the original design weakness - reinforced timing chains, updated injectors, and new emission system components - plus a minimum 12-month unlimited mileage warranty with nationwide delivery and supply & fit options. Don't pay main dealer premiums. Compare prices from independent Mercedes diesel specialists who know these OM651 twin-turbo engines inside out.
Compare rebuilt OM651 Mercedes SLC 220d/250d engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific Mercedes SLC 220d or 250d. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Mercedes Benz SLC 220d/250d Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes SLC 220d or 250d engine replacement cost in the UK-
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
Question 2What are the signs of timing chain failure on a Mercedes SLC 220d or 250d-
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
Question 3What causes injector failure on a Mercedes SLC 220d or 250d-
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
Question 4Is the Mercedes SLC 220d or 250d engine (OM651) reliable-
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
Question 5How long do Mercedes SLC 220d and 250d engines last-
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
Question 6Is it worth replacing the engine in my Mercedes SLC 220d or 250d-
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
Why Choose UsCompare Mercedes SLC 220d/250dEngine PricesToday
500+ OM651 twin-turbo diesel engines supplied through our network
12-Month Warranty on every rebuilt SLC 220d and 250d engine
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supply & fit available for OM651
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