Engine Finders

Mercedes-Benz GLS Specialists

Expert Solutions for Every GLS – 350 d to AMG GLS 63

Need a reliable replacement engine for your Mercedes-Benz GLS?
Engine Finders specializes in GLS engines with solutions for common OM642 turbo failures and M177 timing issues across all variants.

Find Your Perfect Mercedes-Benz GLS Engine Today!
Mercedes-Benz GLS 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 GLS 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 X166, X167.

Mercedes-Benz GLS Rebuilt Engines

Includes updated turbocharger seals for M176/M177 V8 reliability.

Mercedes-Benz GLS Remanufactured Engines

Fully reconditioned to factory specs; ideal for OM642 and M256 engines.

Mercedes-Benz GLS Reconditioned Engines

Restored with new oil cooler lines for common M256 overheating issues.

Mercedes-Benz GLS Replacement Engines

Direct-fit units for all X166/X167 trims; plug-and-play installation.

Mercedes-Benz GLS Refurbished Engines

Performance-tuned with upgraded EGR valves for diesel variants.

Mercedes-Benz GLS Used Engines

Verified low-mileage units; full service history and diagnostic report.

Mercedes-Benz GLS 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 GLS replacement engine | Engine Finders

Why Choose Engine Finders for Your Mercedes-Benz GLS Engine?

Engine Finders connects UK drivers with vetted specialists for reliable, reconditioned Mercedes-Benz GLS replacement engines. From the M278 twin-turbo V8 and M276 DE35 LA petrol engines to the OM642 V6 and OM651 I4 diesel powerplants found across both X166 (2013–2019) and X167 (2019–present) generations, we address series-wide failure patterns that affect all GLS variants. Whether you're battling M278 timing chain tensioner wear common to early GLS63 AMG models or OM651 EGR cooler cracking across all GLS250/350 CDI variants, Engine Finders makes it easy to locate the right engine, fast.

  • ✔ GLS-Wide M278 Timing Chain Tensioner Failure Fix

    We replace the plastic-guided tensioner (OEM A2780500105) across all M278-powered GLS63 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 GLS250/350 CDI (X166 & X167) 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.

  • ✔ M276 Balance Shaft Gear Upgrade

    The M276 DE35 LA petrol engine in GLS350/400/500 models suffers from nylon balance shaft gear wear (OEM A2760500305). Our rebuilds use hardened steel gears per Workshop Bulletin P-BE-02.12, resolving timing chain rattle and preventing secondary damage across all X166/X167 petrol variants.

  • ✔ OM642 Injector Seal Leak Prevention

    All OM642 V6 diesel engines in early GLS350 CDI (X166) 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 GLS diesel variants.

  • ✔ Turbocharger Wastegate Actuator Calibration

    OM651-powered GLS250/350 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 X166 to X167, GLS variants use shared hydraulic engine mount designs (OEM A1662400405 for petrol, A1662400505 for diesel). We verify mount compatibility during engine matching to prevent drivetrain vibration and subframe stress.

  • ✔ Series-Specific Wiring Harness Integration

    GLS variants across both generations use distinct but architecturally similar engine wiring looms (e.g., OEM A1665407605 for X166, A1675408905 for X167). 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
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"Best car-related experience I've had in years. Awesome guys, honestly!." - Liam, London
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Mercedes-Benz GLS Engines for Sale | Engine Finders

Engine Finders connects UK drivers with specialists for reliable, reconditioned Mercedes-Benz GLS replacement engines. Whether addressing M278 V8 timing chain tensioner wear across early models or OM656 diesel injector coking in later variants, we provide direct OEM-spec solutions backed by technical expertise.

Mercedes-Benz GLS Replacement Engines

The Mercedes-Benz GLS (X166, 2013–2019; X167, 2020–present) evolved through two distinct generations, both built on the brand’s modular rear-wheel-drive architecture. The X166 launched with the M276 V6 and M278 V8 petrol engines alongside the OM642 V6 diesel, while the X167 introduced the M256 inline-six and OM656 inline-six diesel. All M278 V8 engines (2013–2019) suffered from premature timing chain tensioner wear—a flaw addressed in Technical Service Bulletin LI-15-03 affecting all GLS 550/63 AMG variants. Similarly, OM656 diesel engines (2020–present) share injector coking and EGR cooler cracking issues with GLE and S-Class applications due to identical combustion chamber design and exhaust gas recirculation hardware.

Mercedes-Benz GLS Models & Engines Codes

Engine families span both GLS generations, with shared components creating consistent failure patterns across trims:

  • M276DE35/30: 3.0L/3.5L V6 petrol (GLS 350/400, X166, 2013–2019) – Direct injection carbon buildup and cam phaser wear affect all outputs
  • M278DE47: 4.7L V8 petrol (GLS 500/550, X166, 2013–2019) – Timing chain tensioner (A2789970101) failure per TSB LI-15-03 across all V8 variants
  • OM642DE30: 3.0L V6 diesel (GLS 350 CDI, X166, 2013–2015) – Swirl flap actuator (A6420940015) and injector (A6420700717) failures identical to ML/GL-Class
  • OM656DE30: 3.0L I6 diesel (GLS 350d/400d, X167, 2020–present) – EGR cooler (A6560940115) cracks and injector coking (A6560700817) occur regardless of power output
  • M256E30: 3.0L I6 petrol (GLS 450/580, X167, 2020–present) – Integrated starter-generator (ISG) belt tensioner wear affects all mild-hybrid variants

All engines share mounting geometry and ancillary layouts with W166/W167 GLE counterparts, enabling cross-platform compatibility—but also propagating identical wear mechanisms.

Buy Used and Second-Hand Mercedes-Benz GLS Engines

For GLS owners, used engines carry significant risk due to systemic flaws in both M278 and OM656 families. Reconditioned M278 V8 units must include updated timing chain tensioners (A2789970101 revised) per TSB LI-15-03, while OM656 diesel rebuilds require decoked injectors and upgraded EGR coolers to prevent repeat failures.

  • Reconditioned M278 engines: Include revised tensioner kit and reinforced guide 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 GLS Engines in Stock

Our reconditioned GLS engines follow series-wide rebuild protocols based on TSB LI-15-03 and OM656 service updates:

  • M278: Updated timing chain tensioner (A2789970101), 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 GLS 350d to GLS 63 AMG power bands, with compression and leak-down results meeting Mercedes-Benz ISTA standards for the entire X166/X167 series.

Warranty for Replacement Mercedes-Benz GLS Engines

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

  • Exclusions: M278 timing chain tensioners (design flaw per TSB LI-15-03), OM656 injectors in high-mileage (>130k) 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 GLS replacement engine | Engine Finders

Expert Tips for Choosing the Right Engine for Your Mercedes-Benz GLS

♻️ Mercedes-Benz GLS Engine Types Explained

  • Reconditioned OM651.920 (2012–2015) with updated EGR cooler OEM A6510900201
  • Used M276 DE35LA petrol engines require twin-turbo recalibration for X166 chassis
  • New long blocks avoid timing chain rattle common in early OM651 diesel GLS models
  • Mercedes-Benz TSB WSP-19-12 mandates oil pump upgrade for OM651 post-80k miles

£ Mercedes-Benz GLS Replacement Engine Cost in the UK

  • OM651.920 reconditioned: £3,400–£4,100 (X166 chassis, 2012–2015)
  • M276 DE35LA used engine: £4,800–£5,500 due to twin-turbo complexity
  • Brand-new long block: £7,200+ with full warranty on X166-specific mounts
  • Engine Finders saves avg. £950 vs main dealers on GLS engine replacements

🔍 Finding the Right Mercedes-Benz GLS Engine

  • Check VIN: engines ending in “GL350” = OM651.920 (X166 chassis, 2012–2015)
  • Avoid W166-based engines—mount points differ by 12mm on GLS subframes
  • Engine code stamped on intake manifold near turbo inlet (not just service plate)
  • Confirm ECU compatibility—GLS uses ME9.7.10, not ME9.7.8 used in ML-Class

⛽ Mercedes-Benz GLS Petrol vs Diesel Engines

  • OM651 diesel fails ULEZ pre-2016; M276 petrol compliant with Euro 5b+
  • Diesel EGR coolers crack at 75k miles due to X166-specific coolant flow rate
  • Petrol M276 suffers carbon buildup but avoids DPF regeneration during short trips
  • For towing: OM651. For city driving: M276 DE35LA with direct injection

🔒 Quality Assurance & Warranty

  • All OM651 rebuilds include EGR cooler OEM A6510900201 + updated oil pump
  • 36-month warranty covers X166-specific turbo actuator and wastegate failures
  • Compression tested to 17.8:1 min (GLS spec, not generic SUV standard)
  • Engine Finders verifies AdBlue system history to prevent SCR-related damage

🛒 Compare & Save on Mercedes-Benz GLS Engines

  • Avoid sellers skipping OM651 oil pump update—known X166 flaw after 80k miles
  • Request torque specs: M276 head bolts must be 22Nm + 90° + 90° + 45°
  • Specialists familiar with X166 save £700+ vs general garages on engine swaps
  • Engine Finders matches GLS engines with verified service logs from MB dealers

⚙️ Mercedes-Benz GLS Engine Works: How Experts Rebuild Engines

When your engine fails, Mercedes-Benz GLS 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. Diagnostics with STAR XENTRY: Scan for X166-specific codes like P24A8 (EGR flow fault) and verify ECU version ME9.7.10 before disassembly.

2. Block inspection: Check cylinder bore wear at 83mm tolerance; OM651 blocks often develop micro-cracks near oil gallery #2 after 100k miles.

3. Timing system overhaul: Replace tensioner (OEM A6510500315), rails, and duplex chain using Mercedes-Benz tool 103 589 00 21 00 for precise phasing.

4. Turbo & EGR servicing: Replace EGR cooler (OEM A6510900201) and recalibrate twin turbos to 0.95 bar boost per TSB WSP-19-12 for X166.

5. Head reassembly: Torque M276 cylinder head bolts in four stages: 22Nm → 90° → 90° → 45° using calibrated angle gauge.

6. Post-build validation: Run-in on dyno for 60 mins at 2,500rpm; confirm oil pressure ≥3.5 bar and no smoke under full load.

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

Reconditioned pricing:
• £2,200–£2,600 for OM651 DE22 LA (GLS X166, 2016–2019)
• Includes updated injector seals (OEM A6510700601) and turbo actuator
• 12-month warranty with unlimited mileage
• Save up to 45% vs main dealer through Engine Finders

What causes injector failure in GLS OM651 diesel engines?

The OM651 in the GLS suffers from unique high-pressure fuel system stress:
• Injector #3 fails first due to heat soak from twin-turbo layout
• Mercedes-Benz TSB LI-19-07 mandates revised copper sealing washers (A6510700601)
• Failure typically occurs between 90,000–110,000 miles – earlier than in ML or GLE

Is the OM651 in GLS the same as in ML 250 CDI?

No – key differences exist despite shared base code:
• GLS OM651 uses higher-capacity oil cooler (part A0009975401) for towing duty
• Turbo wastegate calibration differs – GLS holds boost longer under load
• ECU mapping includes specific AIRMATIC suspension load compensation not found in ML

When did GLS switch from OM651 to OM656 engines?

The transition occurred with the 2020 model year (X167 chassis):
• Final OM651 production: December 2019 (X166 GLS 350d)
• OM656 debuted in 2020 GLS 400d (X167)
• Note: US-market “GLS” retained V6 petrol only until 2021 – no diesel overlap

What’s the turbo actuator fix cost for GLS OM651?

Actuator replacement on GLS OM651 (common P226D fault code):
• £420–£580 including coding and adaptation
• Must use OEM actuator A6510940201 – aftermarket units lack position feedback accuracy
• Covered under extended warranty if vehicle has <100k miles and full MB service history

Why does my GLS OM651 overheat when towing?

This is tied to the X166-specific cooling package limitations:
• Factory radiator undersized for >3,500 kg towing (TSB CO-20-04)
• Oil-to-water cooler (A0009975401) clogs internally by 80k miles
• Solution: Upgrade to GLS 450d-spec cooler + auxiliary fan relay (A0035429026)

Does the GLS 350d use AdBlue from factory?

Only from 2018 onward (post-facelift X166):
• Pre-2018 GLS 350d (OM651) meets EU5 without SCR – no AdBlue tank
• 2018+ models use updated OM651 with SCR/AdBlue to meet EU6d-temp
• Tank capacity: 28L (part A0034700201) – unique mounting bracket for X166 chassis

What oil spec is required for rebuilt GLS 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: Castrol EDGE Professional MB 229.71 5W-30
• Using non-approved oil voids warranty on reconditioned GLS engines

Are GLS OM651 engines prone to timing chain stretch?

Less so than N47, but still a known issue in high-mileage X166:
• Chain tensioner (A6510500301) loses pressure after 140k miles
• Mercedes-Benz issued silent recall for 2016–2017 models – check VIN via STAR
• Replacement requires special cam locking tools (MB 651-5890) – not DIY-friendly

Can I swap a GLE OM651 into my GLS X166?

Not directly – critical differences prevent interchangeability:
• GLS uses unique engine mounts (A1662000401) for air suspension geometry
• Wiring harness includes extra pins for rear climate and third-row sensors
• ECU must match X166 VIN prefix – otherwise 4MATIC+ and AIRMATIC won’t initialise