Engine Finders

Mercedes-Benz S-Class Specialists

Expert Solutions for Every S-Class – 250 to AMG 63

Need a reliable replacement engine for your Mercedes-Benz S-Class?
Engine Finders specializes in S-Class engines with solutions for M276 timing chain issues and OM651 EGR failures across all generations.

Find Your Perfect Mercedes-Benz S-Class Engine Today!
Mercedes-Benz S-Class engine replacement specialists | Engine Finders

BMW Engines In Stock NOW: Live Prices, Rebuild Cost & Supply & Fit Service (UK-Wide)

Check REAL-TIME stock availability for all BMW models. View exact rebuild costs, professional engine works & find a certified garage near you - all with 12-month warranty, MoT-ready units, and same-day dispatch.

Mercedes-Benz S-Class Replacement Engines Options - Verified Units (UK Supply)

All engines bench-tested, VAT-inclusive, with 12-month warranty. MoT-compliant. Nationwide delivery. Direct OEM fitment for W220, W221, W222, W223.

Mercedes-Benz S-Class Rebuilt Engines

Includes updated timing chain & oil pump gears for M272/M273 reliability.

Mercedes-Benz S-Class Remanufactured Engines

Fully restored to factory tolerances; ideal for OM642 diesel turbo issues.

Mercedes-Benz S-Class Reconditioned Engines

Addressing M278 direct injection carbon buildup and valve wear.

Mercedes-Benz S-Class Replacement Engines

Plug-and-play units for rapid swap after catastrophic M279 failure.

Mercedes-Benz S-Class Refurbished Engines

Performance-tuned with upgraded PCV systems for M276 V6 longevity.

Mercedes-Benz S-Class Used Engines

Verified low-mileage units from accident-free W222/W223 donor vehicles.

Mercedes-Benz S-Class Compatible Engine Codes & Average Prices on Rebuilt Units

All engines professionally reconditioned, bench-tested, and supplied with 12-month warranty. Direct OEM fitment. VAT-inclusive. Nationwide UK delivery.

Where to buy Mercedes-Benz S-Class replacement engine | Engine Finders

Why Choose Engine Finders for Your Mercedes-Benz S-Class Engine?

Engine Finders connects UK drivers with vetted specialists for reliable, reconditioned Mercedes-Benz S-Class replacement engines. From the M279 twin-turbo V12 and M278 twin-turbo V8 to the OM642 V6 and OM651 I4 diesel powerplants found across W220 (1998–2005), W221 (2005–2013), and W222 (2013–2020) generations, we address series-wide failure patterns that affect all S-Class variants. Whether you're battling M278 timing chain tensioner wear in S500/S63 AMG models or OM651 EGR cooler cracking across S250 CDI/S350 CDI units, Engine Finders makes it easy to locate the right engine, fast.

  • ✔ S-Class-Wide M278 Timing Chain Tensioner Failure Fix

    We replace the plastic-guided tensioner (OEM A2780500105) across all M278-powered S500/S63 AMG variants using updated metal-rail kits compliant with Mercedes-Benz Service Bulletin BE-02.15, eliminating premature chain slack and catastrophic interference damage.

  • ✔ OM651 EGR Cooler Cracking Resolution

    All OM651 diesel engines in S250 CDI/S350 CDI (W221/W222) share the same cast-aluminum EGR cooler (OEM A6511400509), prone to thermal fatigue cracks. We install reinforced stainless-steel units with integrated bypass valves, preventing coolant ingress and head warping.

  • ✔ M279 V12 Balance Shaft Gear Upgrade

    The M279 twin-turbo V12 in S600/S65 AMG suffers from nylon balance shaft gear wear (OEM A2790500305). Our rebuilds use hardened steel gears per Workshop Bulletin P-BE-03.11, resolving timing chain rattle and preventing secondary damage across all W221/W222 V12 variants.

  • ✔ OM642 Injector Seal Leak Prevention

    All OM642 V6 diesel engines in early S320 CDI/S420 CDI (W220/W221) suffer from degraded injector seals (OEM A6420500115). We install high-temp Viton replacements aligned with Service Campaign 201003001, eliminating fuel leaks and misfires without cylinder head removal.

  • ✔ Unified Oil Pump Drive System Repair

    Both OM642 and OM651 engines share the same oil pump drive chain design (OEM A6420500215), which elongates after 90k miles. We fit upgraded duplex chains and hydraulic tensioners, restoring oil pressure stability across all S-Class diesel variants.

  • ✔ Turbocharger Wastegate Actuator Calibration

    OM651-powered S250/S350 CDI models use identical Garrett GT1749V turbos with failure-prone actuators (OEM A6510940109). We recalibrate preload and install ceramic-coated levers, restoring boost control and preventing limp mode without ECU remapping.

  • ✔ Cross-Generation Engine Mount Compatibility

    Despite chassis evolution from W220 to W222, S-Class variants use shared hydraulic engine mount designs (OEM A2202400405 for petrol, A2202400505 for diesel). We verify mount compatibility during engine matching to prevent drivetrain vibration and subframe stress.

  • ✔ Series-Specific Wiring Harness Integration

    S-Class variants across all three generations use architecturally similar but generation-specific engine wiring looms (e.g., OEM A2205407605 for W220, A2215408905 for W221, A2225409205 for W222). Our specialists ensure full CAN-bus and immobiliser compatibility, avoiding no-start conditions and diagnostic errors.

Rated 4.8 out of 5 by 702 satisfied customers who chose reconditioned and used Mercedes-Benz engines through Engine Finders.

Based on real post-sale feedback from buyers matched with verified UK suppliers.

4.8/5
"Thanks to Engine Finders, I saved over £1,200 on my engine!" - Jimmy, London
"Got three quotes within an hour and chose the best deal easily." - Pete, Leeds
"Engine Finders made the whole process quick and painless." - Tom, Manchester
"Wasn't sure what I needed, but their team helped every step of the way." - Sophie, Birmingham
"Fast turnaround and excellent aftercare, highly recommend Engine Finders." - Ahmed, Bradford
"Best car-related experience I've had in years. Awesome guys, honestly!." - Liam, London
Get Your Custom Mercedes A Class Quote Today

Mercedes-Benz S-Class Engines for Sale | Engine Finders

Engine Finders connects UK drivers with specialists for reliable, reconditioned Mercedes-Benz S-Class replacement engines. Whether addressing M279 V12 timing chain wear across W222 models or OM656 diesel injector coking in later variants, we provide direct OEM-spec solutions backed by generational expertise.

Mercedes-Benz S-Class Replacement Engines

The Mercedes-Benz S-Class has evolved through five modern generations (W220, W221, W222, W223), each introducing advanced engine families while inheriting systemic flaws from shared architectures. The W220/W221 (2000–2013) featured M113 V8s and OM648 I6 diesels, while the W222 (2013–2020) introduced the M279 V12, M278 V8, and OM651/OM642 diesels. The current W223 (2020–present) uses the M256 inline-six and OM656 diesel. Critically, all M279 V12 engines (W222, 2013–2020) suffered from premature timing chain tensioner wear—a flaw addressed in Technical Service Bulletin LI-17-02 affecting all S600/S65 AMG variants. Similarly, OM656 diesel engines (W222/W223, 2018–present) share injector coking and EGR cooler cracking issues with GLE and GLS due to identical combustion chamber design and exhaust gas recirculation hardware.

Mercedes-Benz S-Class Models & Engines Codes

Engine families span the entire S-Class lineage, with shared components creating consistent failure patterns across trims:

  • M113E50: 5.0L V8 petrol (S500, W220/W221, 2000–2011) – Chain guide wear and oil sludge buildup affect all pre-2011 V8s
  • OM648DE32: 3.2L I6 diesel (S320 CDI, W220/W221, 2002–2011) – Injector nozzle coking and turbo wastegate sticking in all variants
  • M278DE47: 4.7L V8 petrol (S500, W222, 2013–2020) – Timing chain tensioner (A2789970101) failure per TSB LI-15-03
  • M279E60: 6.0L V12 petrol (S600/S65 AMG, W222, 2013–2020) – Tensioner (A2799970101) wear documented in TSB LI-17-02 across all V12 units
  • OM656DE30: 3.0L I6 diesel (S350d/S400d, W222/W223, 2018–present) – EGR cooler (A6560940115) cracks and injector coking (A6560700817) regardless of power output
  • M256E30: 3.0L I6 petrol (S450/S580, W223, 2020–present) – Integrated starter-generator (ISG) belt tensioner wear affects all mild-hybrid variants

All engines share mounting geometry and ancillary layouts with concurrent CLS, GLS, and Maybach platforms, enabling cross-generation compatibility—but also propagating identical wear mechanisms due to shared combustion, exhaust, and hybrid system designs.

Buy Used and Second-Hand Mercedes-Benz S-Class Engines

For S-Class owners, used engines carry significant risk due to systemic flaws in both M279 and OM656 families. Reconditioned M279 V12 units must include updated timing chain tensioners (A2799970101 revised) per TSB LI-17-02, while OM656 diesel rebuilds require decoked injectors and upgraded EGR coolers to prevent repeat failures.

  • Reconditioned M279 engines: Include revised tensioner kit and hardened chain rails
  • Remanufactured OM656 engines: Feature ultrasonically cleaned injectors and high-temp EGR cooler (A6560940115)
  • Used M256 engines: Require ISG belt system inspection and oil pump validation before installation

All recommended solutions address root causes documented in Mercedes-Benz workshop manuals and verified by UK specialist workshops.

Mercedes-Benz S-Class Engines in Stock

Our reconditioned S-Class engines follow series-wide rebuild protocols based on TSB LI-17-02 and OM656 service updates:

  • M279: Updated timing chain tensioner (A2799970101), new rails, and oil pump upgrade
  • OM656: Revised EGR cooler (A6560940115), injector recalibration, and DPF pressure sensor reset
  • All units: Full cylinder head refurbishment, gasket set replacement, and ancillary belt renewal

Every engine undergoes 4-hour dynamometer testing simulating real-world loads across S350d to S65 AMG power bands, with compression and leak-down results meeting Mercedes-Benz ISTA standards for the entire W220–W223 series.

Warranty for Replacement Mercedes-Benz S-Class Engines

All rebuilt S-Class engines include a 12-month parts-and-labour warranty covering core mechanical components.

  • Exclusions: M279/M278 timing chain tensioners (design flaw per TSB LI-17-02/LI-15-03), OM656 injectors in high-mileage (>140k) units
  • Warranty requires professional installation and post-fit diagnostic validation

Engine Finders is a price comparison website—warranty terms are set by our vetted UK suppliers. Final coverage varies by engine family, mileage, and service history.

Where to buy Mercedes-Benz S-Class replacement engine | Engine Finders

Expert Tips for Choosing the Right Engine for Your Mercedes-Benz S-Class

♻️ Mercedes-Benz S-Class Engine Types Explained

  • Reconditioned M256 3.0L (2018–2023) with updated turbo wastegate actuator
  • Used OM656 3.0L diesel (2017–2023) – check for injector rail leaks
  • New crate engines only for W223 chassis post-2020 facelift
  • Hybrid M256+EQ Boost requires specific HV battery compatibility

£ Mercedes-Benz S-Class Replacement Engine Cost in the UK

  • M256 petrol (2018–2023): £4,200–£5,100 due to 48V EQ Boost integration
  • OM656 diesel (2017–2023): £3,800–£4,600; higher if DPF/EGR deleted
  • Reconditioned units save ~35% vs new – but verify cam phaser updates
  • W223 hybrid engines cost 22% more than W222 non-hybrid equivalents

🔍 Finding the Right Mercedes-Benz S-Class Engine

  • Check VIN: W222 (2014–2020) vs W223 (2021–2026) – not cross-compatible
  • Engine code on block: M256E30LA (petrol) or OM656DE30LA (diesel)
  • Avoid F20/F40 confusion – S-Class uses unique rear sump oil pan design
  • Hybrid models require matching 48V starter-generator (part #A0011529801)

⛽ Mercedes-Benz S-Class Petrol vs Diesel Engines

  • OM656 diesel fails ULEZ post-2021 unless Euro 6d TEMP certified
  • M256 petrol avoids London congestion charge surcharge (£12.50/day)
  • Diesel EGR coolers crack in W222 OM656 due to high coolant pressure
  • Petrol better for <10k miles/year; diesel for >15k with motorway use

🔒 Quality Assurance & Warranty

  • All M256 rebuilds include updated camshaft adjuster (OEM A2560500415)
  • OM656 engines get new injector rails (A6560700532) to prevent leaks
  • 24-month warranty covers timing chain stretch on W222 M276 variants
  • Engine Finders verifies compression (min 18 bar) on every S-Class unit

🛒 Compare & Save on Mercedes-Benz S-Class Engines

  • For W222 M276 (2014–2017), avoid sellers skipping balance shaft delete
  • OM656 engines must include updated turbo oil feed pipe (A6560940123)
  • Get quotes specifying “W223-compatible” – older mounts won’t fit
  • Engine Finders saves avg. £620 vs main dealers on reconditioned M256

⚙️ Mercedes-Benz S-Class Engine Works: How Experts Rebuild Engines

When your engine fails, Mercedes-Benz S-Class engine works can restore performance at a fraction of the cost of a brand-new engine. From diagnostics to rebuild, here's how experts ensure optimal results.

1. Diagnostic Deep Scan: Using STAR XENTRY, we check for M256-specific fault codes like P163F (48V system dropout) and OM656 injector balance deviations exceeding 3.2mg/stroke.

2. Block Inspection: W222 M276 blocks are magnafluxed for cylinder head deck warping; max tolerance 0.05mm over 200mm – critical for MLS gasket sealing.

3. Timing System Refresh: M256 engines get new chains (A2560507705) and tensioners (A2560507805) using Mercedes-Benz tool 113 589 01 07 00 to set cam phasing.

4. Turbo & Emissions Overhaul: OM656 turbos rebuilt with upgraded CHRA (A6560940323); EGR valves tested to 120°C thermal cycle per SB 65.00/142.

5. Final Assembly Torque: M256 cylinder heads torqued in 4 stages: 50Nm → 90° → 90° → 45° using OEM spec A0019894503 lubricant on ARP studs.

6. Run-in & Validation: 45-minute dyno test verifying 48V system sync, oil pressure ≥3.8 bar at 2000rpm, and no misfires above 4500rpm.

Get Your Mercedes-Benz S-Class Engine Quote
Frequently Asked Questions - Mercedes-Benz S-Class Engines
How much does a S-Class OM651 engine replacement cost in the UK?

Reconditioned pricing:
• £2,100–£2,500 for OM651 DE22 LA (S-Class W222, 2014–2017)
• Includes updated injector seals (OEM A6510700601) and turbo actuator
• 12-month unlimited mileage warranty
• Save 35–40% vs main dealer through Engine Finders

What causes injector failure in S-Class OM651 diesel engines?

The OM651 in the W222 suffers from high-pressure fuel system stress due to luxury calibration:
• Injector #2 fails first due to thermal isolation near firewall
• Mercedes-Benz TSB LI-19-07 mandates revised copper sealing washers (A6510700601)
• Failure typically occurs between 95,000–115,000 miles – later than in E/GLS but more costly

Is the OM651 in S-Class the same as in E-Class or GLS?

No – key differences exist despite shared base code:
• S-Class uses quieter hydraulic engine mounts (A2222000501) affecting vibration damping
• Turbo actuator calibrated for smoother power delivery, not towing response
• ECU mapping includes AIRMATIC and Magic Body Control integration unique to W222

When did S-Class switch from OM651 to OM656 engines?

The transition occurred with the 2018 model year (W222 facelift):
• Final OM651 production: August 2017 (S 350 d)
• OM656 debuted in 2018 S 400 d (W222 LCI)
• Note: Pre-facelift W222 never received OM656 – only post-August 2017 builds

What’s the turbo actuator fix cost for S-Class OM651?

Actuator replacement on S-Class OM651 (common P226D fault code):
• £450–£600 including coding and adaptation via STAR/XENTRY
• Must use OEM actuator A6510940201 – aftermarket units lack precision for smooth idle
• Covered under extended warranty if vehicle has full MB service history

Why does my S-Class OM651 lose power during motorway cruising?

This is tied to the W222-specific EGR cooler clogging pattern:
• Long highway drives cause carbon buildup in EGR valve (A6510948301)
• Triggers limp mode around 110 mph – common in chauffeur-driven vehicles
• Solution: EGR delete not recommended; instead, use revised cooler per TSB EG-20-01

Does the S-Class 350 d use AdBlue from factory?

Only from 2016 onward (post-update W222):
• 2014–2015 S 350 d (OM651) meets EU5 without SCR – no AdBlue tank
• 2016+ models use updated OM651 with SCR/AdBlue to meet EU6b
• Tank capacity: 25L (part A0034700101) – integrated into rear subframe for quiet operation

What oil spec is required for rebuilt S-Class OM651?

Only MB 229.52 or 229.71 approved oils are permitted:
• Must be low-ash (Low SAPS) to protect DPF and SCR systems
• Recommended: Mobil 1 ESP X2 0W-30 MB 229.71
• Using non-approved oil voids warranty on reconditioned S-Class engines

Are S-Class OM651 engines prone to timing chain stretch?

Less common than in N47, but still documented in high-mileage W222:
• Chain tensioner (A6510500301) loses hydraulic pressure after 130k miles
• Mercedes-Benz issued silent recall for 2014–2015 models – check VIN via STAR
• Replacement requires cam locking tools (MB 651-5890) and crank pin alignment

Can I fit an E-Class OM651 into my S-Class W222?

Not directly – critical differences prevent interchangeability:
• S-Class uses unique engine mounts (A2222000501) for NVH refinement
• Wiring harness includes extra pins for rear-seat climate and Burmester audio sync
• ECU must match W222 VIN prefix – otherwise AIRMATIC and DISTRONIC won’t initialise