Mercedes-Benz GLS Engine Replacement

How It Works

3 Simple Stepsto Finding the Best Mercedes Benz GLS Replacement Engine

Get Instant Quotes from Mercedes - Benz Engine Specialists Across the UK - 100% free, no obligation. Most replacements completed within 3-5 days.

Most replacements completed within 3-5 days.

12-Month Warranty

Supply & Fit Available

Nationwide Delivery

Trusted UK Suppliers

Live UK Engine Market Data

What Are UK Drivers Paying for Mercedes-Benz GLS Engine Replacement?

Shows typical UK rebuilt engine costs for Mercedes-Benz GLS variants with documented failures, engine codes, fuel types and sizes from market data.

Mercedes Benz GLS live market price reference

Average Market Prices

Mercedes-Benz GLS (X166) GLS 4002012-2019£4,500-£7,200
Timing chain tension
M276Petrol 3.0L
Mercedes-Benz GLS (X166) GLS 5002012-2019£5,500-£9,200
Timing chain guide
M278Petrol 4.7L
Mercedes-Benz GLS (X166) GLS 63 AMG2012-2017£6,200-£10,500
Turbo bearing wear
M157Petrol 5.5L
Mercedes-Benz GLS (X166) GLS 63 AMG2017-2019£7,000-£12,500
Oil consumption
M177Petrol 4.0L
Mercedes-Benz GLS (X167) GLS 400d2019-2026£4,500-£7,200
AdBlue system fault
OM656Diesel 3.0L
Mercedes-Benz GLS (X167) GLS 4502019-2026£5,200-£8,800
HPFP failure
M256Petrol 3.0L
Mercedes-Benz GLS (X167) AMG GLS 632019-2026£7,500-£13,500
Turbo bearing wear
M177Petrol 4.0L
Mercedes-Benz GLS (X164) GL 350 CDI2006-2012£3,200-£5,200
Oil cooler seal leak
OM642Diesel 3.0L
Mercedes-Benz GLS (X164) GL 420 CDI2006-2012£4,500-£7,200
Injector failure
OM629Diesel 4.0L
Mercedes-Benz GLS (X164) GL 4502006-2012£4,000-£6,800
Balance shaft wear
M273Petrol 5.5L
Mercedes-Benz GLS (X164) GL 5002006-2012£4,200-£7,000
Intake flap failure
M273Petrol 5.5L
Mercedes-Benz GLS (X166) GLS 250d2012-2019£2,900-£4,400
Injector seal leak
OM651Diesel 2.1L
Mercedes-Benz GLS (X166) GLS 350d2012-2017£3,400-£5,500
Oil cooler seal leak
OM642Diesel 3.0L
Mercedes-Benz GLS (X166) GLS 350d2017-2019£4,000-£6,200
EGR cooler fault
OM656Diesel 3.0L
Mercedes-Benz GLS (X166) GLS 400d2017-2019£4,200-£6,800
Turbo actuator fail
OM656Diesel 3.0L

Last updated: 22 May, 14:59

Customer Reviews

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Models We Cover

Mercedes-Benz GLS Engine ReplacementAll Variants Covered

From the economical GLS 250d to the high-performance AMG GLS 63, our network of UK Mercedes-Benz GLS engine specialists helps you compare rebuilt, reconditioned and used engine prices. Typical price range for a rebuilt unit with 12-month warranty - supply & fit available nationwide.

Core Diesel Range

Specs204hp

Years2013-2019

Rebuilt£2,900-£4,400

Compare GLS 250d Engine Prices

Core Petrol Range

Performance & Legacy Range

Variant Directory

All Mercedes-Benz GLS Variants - Engine Replacement Coverage

A full alphabetical listing of every Mercedes-Benz GLS trim covered by our network. All entries link to a dedicated variant page, where prices are further broken down by engine code, model year, and condition type. Click a live link to compare quotes.

Diesel Variants

GL 320 CDIGL 350 BlueTECGL 350 CDIGL 420 CDIGLS 250dGLS 350dGLS 350d 4MATICGLS 400dGLS 400d 4MATICGLS 450d

Petrol Variants

GL 450GL 500GLS 350GLS 400GLS 450GLS 450 4MATICGLS 500GLS 500 4MATICGLS 580GLS 580 4MATIC

Performance Variants

AMG GLS 63 4MATIC+GLS 63 AMGGLS 63 AMG 4MATIC

Engine Codes

Mercedes-Benz GLS Engine CodesFull Technical Specifications & Replacement Guide

Every engine code fitted to the Mercedes-Benz GLS across all generations, with technical specs, compatible variants and trims, known failure points, and average rebuilt prices from UK specialists. Select any engine code to compare quotes.

Diesel Engines

Extracted from detailed diesel engine families across Mercedes Benz GLS variants.

Petrol Engines

Extracted from detailed petrol and performance engine families across Mercedes Benz GLS variants.

Hybrid / Electrified Engines

Extracted from electrified powertrains and hybrid engine families used in Mercedes Benz GLS variants.

Can't find your engine code?

Can’t find your engine code? Enter your registration number above - we’ll instantly identify the exact unit, its technical specifications, and live replacement prices from UK Mercedes-Benz GLS engine specialists. Every rebuilt engine comes with a minimum 12‑month unlimited mileage warranty.

Enter Your Reg

Common Problems

Mercedes-Benz GLS Engine Problems
What It Costs to Fix & When Replacement Makes Sense

The Mercedes-Benz GLS delivers premium refinement and heavy-duty towing capability, but its complex engine families are not immune to high-mileage wear. Replacement demand is heavily driven by the OM642 V6 diesel timing chain system, M276/M278 petrol VANOS solenoid degradation, and AdBlue emission faults in modern straight-six diesels. Every rebuilt Mercedes-Benz GLS engine supplied through EngineMarket includes upgraded internal components designed to permanently address the original failure point, backed by a minimum 12‑month unlimited mileage warranty. Use the cost breakdowns below to decide whether a targeted repair or a full engine replacement offers the best long-term value for your SUV.

Every rebuilt engine includes a minimum 12-month unlimited mileage warranty.

1. Mercedes-Benz GLS Timing Chain Failure

Why OM642 V6 Diesel Engines Suffer Premature Wear

Affected Models

Mercedes-Benz GLS 350d, GL 350 CDI, GLS 350 BlueTEC (2006-2019, OM642)

Typical Failure Mileage

60,000-90,000 miles

Root Cause

The rear-mounted timing chain tensioner relies on consistent oil pressure and precise tolerances. Over time, chain stretch and plastic guide wear cause slack, leading to cold-start rattling and eventual timing misalignment if maintenance intervals are extended or sub-standard filters are used.

Repair Options & Estimated Costs (UK ranges)

Repair Tier	Dealer Price	Specialist Price	What It Involves	Longevity / Suitability
Minor - Preventative Timing Chain & Guide Replacement Minor	£1,800 - £2,600	£1,100 - £1,800	Full chain kit swap with upgraded tensioner, guide rails and oil pump chain inspection	Extends life by 40,000-60,000 miles if caught before severe rattling occurs
Full Replacement - Rebuilt / Reconditioned OM642 Engine Best Value	£7,500 - £11,000	£4,200 - £6,800	Complete engine swap with reinforced timing assembly, new ancillaries and bench-tested calibration	Permanent solution with 12-month warranty; eliminates cumulative internal wear

Our Recommendation

Best next step for mercedes-benz gls timing chain failure

On a Mercedes-Benz GLS worth £12,000-£25,000, early chain replacement is only cost-effective if the block is otherwise pristine. Once cold-start rattle exceeds 65,000 miles, chain slack has usually damaged tensioners and guides internally. We typically recommend a rebuilt unit, as it resolves timing issues while simultaneously refreshing the oil cooler and turbo seals.

Compare rebuilt OM642 engine prices for your Mercedes-Benz GLS

Don't Let Engine Failure Write Off Your Mercedes-Benz GLS

From OM642 timing chain degradation to modern OM656 AdBlue faults, Mercedes-Benz GLS engine failures are rarely simple fixes. Attempting piecemeal repairs on a luxury SUV often leads to recurring faults, inflated dealer invoices, and compromised towing capability. EngineMarket connects you directly with vetted UK specialists who stock precision-rebuilt GLS engines designed with upgraded components to permanently resolve known weak points. Every unit includes a minimum 12‑month unlimited mileage warranty, nationwide delivery and optional mobile supply & fit. Compare live quotes today and secure a specialist-grade replacement without the main dealer premium.

Compare Mercedes-Benz GLS Engine Replacement Prices Now →

Mercedes-Benz GLS Engine Problems
What It Costs to Fix & When Replacement Makes Sense

The Mercedes-Benz GLS delivers premium refinement and heavy-duty towing capability, but its complex engine families are not immune to high-mileage wear. Replacement demand is heavily driven by the OM642 V6 diesel timing chain system, M276/M278 petrol VANOS solenoid degradation, and AdBlue emission faults in modern straight-six diesels. Every rebuilt Mercedes-Benz GLS engine supplied through EngineMarket includes upgraded internal components designed to permanently address the original failure point, backed by a minimum 12‑month unlimited mileage warranty. Use the cost breakdowns below to decide whether a targeted repair or a full engine replacement offers the best long-term value for your SUV.

Affected Models

Mercedes-Benz GLS 350d, GL 350 CDI, GLS 350 BlueTEC (2006-2019, OM642)

Typical Failure Mileage

60,000-90,000 miles

Root Cause

The rear-mounted timing chain tensioner relies on consistent oil pressure and precise tolerances. Over time, chain stretch and plastic guide wear cause slack, leading to cold-start rattling and eventual timing misalignment if maintenance intervals are extended or sub-standard filters are used.

Minor - Preventative Timing Chain & Guide Replacement

Dealer

£1,800 - £2,600

Specialist

£1,100 - £1,800

Full chain kit swap with upgraded tensioner, guide rails and oil pump chain inspection

Extends life by 40,000-60,000 miles if caught before severe rattling occurs

Full Replacement - Rebuilt / Reconditioned OM642 Engine

Dealer

£7,500 - £11,000

Specialist

£4,200 - £6,800

Complete engine swap with reinforced timing assembly, new ancillaries and bench-tested calibration

Permanent solution with 12-month warranty; eliminates cumulative internal wear

Our Recommendation

Best next step for mercedes-benz gls timing chain failure

On a Mercedes-Benz GLS worth £12,000-£25,000, early chain replacement is only cost-effective if the block is otherwise pristine. Once cold-start rattle exceeds 65,000 miles, chain slack has usually damaged tensioners and guides internally. We typically recommend a rebuilt unit, as it resolves timing issues while simultaneously refreshing the oil cooler and turbo seals.

Compare rebuilt OM642 engine prices for your Mercedes-Benz GLS

Don't Let Engine Failure Write Off Your Mercedes-Benz GLS

From OM642 timing chain degradation to modern OM656 AdBlue faults, Mercedes-Benz GLS engine failures are rarely simple fixes. Attempting piecemeal repairs on a luxury SUV often leads to recurring faults, inflated dealer invoices, and compromised towing capability. EngineMarket connects you directly with vetted UK specialists who stock precision-rebuilt GLS engines designed with upgraded components to permanently resolve known weak points. Every unit includes a minimum 12‑month unlimited mileage warranty, nationwide delivery and optional mobile supply & fit. Compare live quotes today and secure a specialist-grade replacement without the main dealer premium.

Compare Mercedes-Benz GLS Engine Replacement Prices Now →

Disclaimer: 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 EngineMarket’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-Benz GLS and engine code. Every engine supplied through EngineMarket carries a minimum 12‑month unlimited mileage warranty - always confirm exact terms with your chosen supplier.

12-Month Warranty

Upgraded Components

Nationwide UK Delivery

Save vs Main Dealer Price

Replacement Engine Options

Mercedes-Benz GLS Engine TypesOptions, Costs & What to Expect

Every engine type is available through the UK network with typical price ranges based on variant, engine code and budget.

Reconditioned

Mercedes-Benz GLS Reconditioned Engines (Recon)

Expertly dismantled units undergo rigorous cleaning, testing and replacement of all worn seals to restore factory performance standards.

Typical price range

£3,500 - £7,200

(supply only)

Pricing varies by variant and mileage; quotes confirmed upon registration check.

Compare reconditioned Mercedes-Benz GLS engine prices

Reconditioned

Our network sources high‑specification OM642 and OM656 units, replacing gaskets, filters and belts while preserving matched cylinder compression.

Dyno‑tested performance guarantees factory tolerances for X166 and X167 chassis models across the UK.
Upgraded timing chain kits address known wear patterns without inflating your overall replacement budget.
Backed by minimum twelve month unlimited mileage coverage for complete peace of mind on heavy towing duties.

Rebuilt

Mercedes-Benz GLS Rebuilt Engines

Comprehensive teardown allows engineers to inspect crankshafts and blocks, machining surfaces to precise manufacturer specifications.

Typical price range

£4,200 - £8,500

(supply only)

Specialist machining costs apply to heavily damaged blocks; registration lookup confirms exact quotes.

Get rebuilt Mercedes-Benz GLS engine quotes

Rebuilt

Critical internal components like pistons, bearings and cam followers receive factory replacements to eliminate early failure risks.

Ideal for X166 GLS 350d and 400d models suffering from OM642 timing chain or oil cooler seal degradation.
Pressure testing ensures zero coolant mixing and optimal combustion chamber integrity before dispatch.
Delivered fully dressed with ancillaries for immediate installation by certified independent fitters nationwide.

Used

Mercedes-Benz GLS Used Engines

Sourced from verified UK breaker networks, these units offer rapid turnaround for budget‑conscious owners needing immediate roadworthiness.

Typical price range

£1,800 - £4,000

(supply only)

Mileage and service history vary; we recommend compression testing prior to final installation approval.

Check used Mercedes-Benz GLS engine availability

Used

Sourced from low‑mileage accident write‑offs, these untested blocks suit short‑term ownership or owners planning immediate full rebuilds themselves.

Best suited for X164 GL models where original part availability is scarce but running condition remains paramount.
Visual inspections confirm intact sumps, mounts and wiring harness connectors prior to network dispatch.
Twelve month coverage applies strictly to internal mechanical defects rather than external ancillary components.

Remanufactured

Mercedes-Benz GLS Remanufactured Engines

Complete strip‑down and factory‑level re‑engineering restores every component to new specification, including the latest engineering revisions.

Typical price range

£5,500 - £11,000

(supply only)

Highest upfront cost ensures showroom reliability; exact pricing depends on standard or AMG variant requirements.

Compare remanufactured Mercedes-Benz GLS engine costs

Remanufactured

Meticulous machining of cylinder bores, crankshaft journals and head mating surfaces guarantees zero tolerance deviations from assembly line standards.

Essential for M177 AMG GLS 63 units requiring precision balancing and reinforced internals for sustained high‑performance use.
Updated ECU calibrations and emission hardware ensure full DVSA compliance without triggering dashboard warning lights.
Comprehensive dyno validation confirms optimal oil pressure, compression and thermal management before final packaging.

Refurbished

Mercedes-Benz GLS Refurbished Engines

Targeted replacement focuses on documented weak points, offering a practical balance between full overhauls and basic salvage alternatives.

Typical price range

£2,500 - £5,500

(supply only)

Scope varies; always request a full component list from your chosen specialist before finalising the purchase.

View refurbished Mercedes-Benz GLS engine options

Refurbished

Specialists address specific failure modes like injector seal leaks or turbo actuator faults without unnecessarily replacing functional internals.

Frequently applied to OM656 straight‑six diesels experiencing early AdBlue heater or EGR cooler malfunctions.
Retains original block integrity while upgrading vulnerable peripheral systems known to degrade under heavy towing loads.
Provides a cost‑effective middle ground when full rebuild budgets are limited but salvage units prove unreliable.

Supply & Fit

Mercedes-Benz GLS Supply & Fit Engines

Turnkey installation coordinates delivery and certified technician labour, eliminating logistical headaches for busy families.

Typical price range

£1,200 - £2,500 added to engine price

Final labour charges depend on location, variant complexity and required ancillary replacements.

Find Mercedes-Benz GLS engine supply & fit deals

Supply & Fit

Mobile and workshop fitting options ensure correct ECU coding, fluid recalibration and thorough road testing before returning your GLS to daily use.

Network fitters handle heavy lifting, subframe removal and precise alignment for both X166 and modern X167 platforms.
Post‑installation diagnostics verify seamless integration with 4MATIC drivetrains and automatic transmission controllers.
Single point of contact manages warranty claims, fluid disposal and post‑fit adjustments for complete peace of mind.

All engine types include a minimum 12‑month unlimited mileage warranty when sourced through EngineMarket. Prices are typical UK market ranges based on historical quote data from our network and depend on exact engine code, variant, mileage and supplier. Use our free comparison tool above - enter your registration to get tailored quotes for your specific Mercedes-Benz GLS within hours.

Engine Sizes

Mercedes-Benz GLS Engines by SizeFind the Right Displacement for Your Variant

Every displacement fitted to the Mercedes-Benz GLS is listed below with compatible engine codes, production years and documented failure notes to help you identify the correct replacement unit.

Mercedes-Benz GLS Diesel Engine Sizes

The 2.1L OM651 four-cylinder diesel served as the entry-level powerplant for the X166 GLS 250d, delivering respectable torque for a large SUV while prioritising fuel economy and lower tax bands. Its compact twin-turbo design made it popular with fleet and private owners seeking reduced running costs without sacrificing the GLS's commanding presence.

Engine Code(s)	OM651
Compatible Models (UK)	GLS 250d, GLS 250d 4MATIC
Production Years	X166, 2013-2019

Common Failure Points

Watch for these known weak points

Injector copper seal leaks, balancer shaft bearing wear on high-mileage units

Get quotes for Mercedes-Benz GLS 2.1L diesel engines

Not sure which engine size your Mercedes-Benz GLS needs? Enter your registration number above - we'll identify the exact displacement, engine code and compatible replacement options instantly. All engines supplied through EngineMarket include a minimum 12‑month unlimited mileage warranty from UK Mercedes-Benz GLS specialists.

Mercedes-Benz GLS Engines Fuel Type

Mercedes-Benz GLS Engines by Fuel Type

Mercedes-Benz GLS Diesel Engines

Diesel power dominates UK GLS replacements, spanning the robust OM642 V6, modern OM656 straight-six, and entry-level OM651 four-cylinder across all three generations.

Common Engine Families

OM642 - 3.0L V6 workhorse (GLS 350d), oil cooler seal and timing chain wear

OM656 - 3.0L straight-six (GLS 400d), sequential turbos, AdBlue system complexity

OM651 - 2.1L four-cylinder (GLS 250d), injector seal leaks, balancer shaft concerns

OM629 - 4.0L V8 diesel (GL 420 CDI), rare high-torque unit, piezo injector sensitivity

Found In

X164 GL (2006-2012) - OM642, OM629

X166 GLS (2012-2019) - OM642, OM651, OM656 (facelift)

X167 GLS (2019-present) - OM656, OM651 (early)

Known For

Exceptional towing capability and motorway refinement across all diesel variants

OM642 oil cooler seal leaks between 60k-90k miles driving replacement demand

OM656 AdBlue heater faults triggering engine start limitations on X167 models

High UK replacement volume on GLS 350d and 400d due to fleet and family usage

Typical Models (UK)

GLS 250d

GLS 350d / 350 BlueTEC

GLS 400d

GLS 450d

GL 350 CDI (pre-2016)

GL 420 CDI (X164 only)

Get quotes for Mercedes-Benz GLS Diesel replacement engines

Not sure which fuel type your Mercedes-Benz GLS has? Enter your registration number above to instantly identify your engine code, fuel system and compatible replacement options - all backed by a minimum 12‑month unlimited mileage warranty from UK Mercedes-Benz GLS specialists.

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Engine Years

Mercedes-Benz GLS Engines by YearWhat Was Fitted & When

This technical timeline covers all major Mercedes-Benz GLS engine changes across three generations, helping owners quickly identify their exact powerplant and compare rebuilt engine prices from UK specialists.

2006 - 2009 - X164 Mercedes-Benz GL Launch

Major Platform Change

The inaugural X164 GL introduced Mercedes’ first true luxury SUV, pairing rugged body-on-frame capability with refined V6 and V8 powertrains.

Key Changes

Launch of X164 architecture replacing the ML-based SUV concept

Introduction of OM642 3.0L V6 diesel and M272 3.5L petrol

M273 4.6L/5.5L V8 added for flagship towing capability

OM629 4.0L V8 diesel launched for heavy-duty European markets

Known For

Robust ladder-frame chassis delivering exceptional off-road articulation

M272 balance shaft gear wear on early 2006-2007 production runs

OM642 oil cooler seals prone to degradation by 60,000 miles

Heavy curb weight accelerates brake and suspension component fatigue

Main Engines

OM642 - 3.0 diesel (GL 320 CDI / 350 CDI)

OM629 - 4.0 diesel (GL 420 CDI)

M272 - 3.5 petrol (GL 350)

M273 - 4.6 / 5.5 petrol (GL 450 / 500)

Popular Models

Mercedes-Benz GL 350 CDI

Mercedes-Benz GL 420 CDI

Mercedes-Benz GL 450

Mercedes-Benz GL 500

Engine Codes Covered

OM642OM629M272M273642.826272.967273.922

Common Replacement Enquiries

Mercedes-Benz GL 350 CDI engine replacement

2006 Mercedes-Benz GLS OM642 timing chain issues

Mercedes-Benz GL 420 CDI injector failure

Get quotes for 2006-2009 Mercedes-Benz GL replacement engines

2006 - 2009 - X164 Mercedes-Benz GL Launch

Major Platform Change

The inaugural X164 GL introduced Mercedes’ first true luxury SUV, pairing rugged body-on-frame capability with refined V6 and V8 powertrains.

Key Changes

Launch of X164 architecture replacing the ML-based SUV concept

Introduction of OM642 3.0L V6 diesel and M272 3.5L petrol

M273 4.6L/5.5L V8 added for flagship towing capability

OM629 4.0L V8 diesel launched for heavy-duty European markets

Known For

Robust ladder-frame chassis delivering exceptional off-road articulation

M272 balance shaft gear wear on early 2006-2007 production runs

OM642 oil cooler seals prone to degradation by 60,000 miles

Heavy curb weight accelerates brake and suspension component fatigue

Main Engines

OM642 - 3.0 diesel (GL 320 CDI / 350 CDI)

OM629 - 4.0 diesel (GL 420 CDI)

M272 - 3.5 petrol (GL 350)

M273 - 4.6 / 5.5 petrol (GL 450 / 500)

Engine Codes Covered

OM642OM629M272M273642.826272.967273.922

Popular Models

Mercedes-Benz GL 350 CDI

Mercedes-Benz GL 420 CDI

Mercedes-Benz GL 450

Mercedes-Benz GL 500

Common Replacement Enquiries

Mercedes-Benz GL 350 CDI engine replacement

2006 Mercedes-Benz GLS OM642 timing chain issues

Mercedes-Benz GL 420 CDI injector failure

Get quotes for 2006-2009 Mercedes-Benz GL replacement engines

Year Finder

Not sure which year your Mercedes Benz GLS was built?

Not sure which year your Mercedes-Benz GLS was built? Enter your registration number and we'll identify the exact engine, model year, and compatible replacement options instantly - all backed by a minimum 12‑month warranty from UK Mercedes-Benz GLS specialists.

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FAQ

Mercedes-Benz GLS Engine ReplacementFrequently Asked Questions

Question 1

How much does it cost to replace a Mercedes-Benz GLS engine in the UK?

Rebuilt Mercedes-Benz GLS engine prices typically range from £3,400 to £13,500 depending on variant, engine code and condition. The OM642 diesel in GLS 350d models sits around £3,400-£5,500, while AMG M177 V8 units command £7,500-£13,500. Supply-only pricing excludes fitting labour.

Key points

• OM642 V6 diesel rebuilt units average £3,400-£5,500 supply-only
• M177 AMG V8 petrol engines range £7,500-£13,500 due to complexity
• Supply & fit adds £1,200-£2,500 depending on workshop location
• Reconditioned units cost more than used but include warranty coverage

Compare rebuilt Mercedes-Benz GLS engine prices from UK specialists

Question 2

Is it worth replacing the engine on a Mercedes-Benz GLS?

Yes, replacing a Mercedes-Benz GLS engine is often worthwhile given the vehicle's high residual value and towing capability. A rebuilt unit with 12-month warranty typically costs less than purchasing a comparable replacement SUV, preserving your investment.

Key points

• GLS residual values remain strong, supporting repair over replacement
• Rebuilt engines include upgraded components addressing original failure points
• Supply & fit services minimise downtime for primary family vehicles
• Warranty coverage protects against repeat failure risks

Get quotes for Mercedes-Benz GLS engine replacement and compare value

Question 3

Which Mercedes-Benz GLS engine is most reliable?

The OM656 3.0L straight-six diesel in GLS 400d models offers the best balance of refinement and reliability among Mercedes-Benz GLS engines. Post-2017 units benefit from updated AdBlue systems and improved timing components compared to earlier OM642 V6 designs.

Key points

• OM656 straight-six diesel features sequential turbocharging and refined internals
• Post-2017 GLS 400d models show reduced oil cooler seal failures
• M256 mild-hybrid petrol offers smooth operation with electric assist
• Regular oil changes with manufacturer-spec fluid extend all engine lifespans

Find a reconditioned OM656 Mercedes-Benz GLS engine with warranty

Question 4

What causes Mercedes-Benz GLS OM642 engine failure?

OM642 engine failures in Mercedes-Benz GLS models most commonly stem from oil cooler seal deterioration and timing chain guide wear. External oil leaks from the V6 valley can lead to low oil pressure if ignored, while chain stretch causes cold-start rattling.

Key points

• Oil cooler seals harden between 60,000-90,000 miles causing external leaks
• Timing chain tensioner wear triggers cold-start rattle on high-mileage units
• EGR valve carbon buildup restricts airflow and triggers limp mode
• Rebuilt OM642 units include reinforced seals and upgraded tensioners

Get quotes for OM642 Mercedes-Benz GLS engine replacement from specialists

Question 5

Can I swap a GLS 350d engine for a 400d unit?

Swapping a Mercedes-Benz GLS 350d OM642 engine for a 400d OM656 unit is technically complex and not recommended without specialist ECU coding and emissions system recalibration. Compatibility issues with wiring harnesses and AdBlue components often outweigh performance benefits.

Key points

• OM642 and OM656 use different engine management architectures
• AdBlue dosing systems and sensor calibrations are not cross-compatible
• 4MATIC transmission software may require dealer-level reprogramming
• Insurance and DVLA documentation must reflect any major powertrain changes

Compare compatible Mercedes-Benz GLS engine options for your variant

Question 6

Should I choose petrol or diesel for a Mercedes-Benz GLS replacement?

Diesel Mercedes-Benz GLS engines like the OM642 and OM656 remain the preferred choice for UK owners prioritising towing capacity and motorway economy. Petrol M256 and M177 units offer smoother refinement but higher fuel costs and lower torque for heavy loads.

Key points

• Diesel GLS variants deliver 20-30% better fuel economy on long journeys
• OM642 and OM656 provide superior low-end torque for towing caravans
• Petrol M256 mild-hybrid offers seamless electric assist and reduced NVH
• AdBlue system maintenance is required for all modern diesel GLS models

Compare diesel and petrol Mercedes-Benz GLS engine prices and availability

Question 7

How long should a Mercedes-Benz GLS engine last?

With proper maintenance, Mercedes-Benz GLS engines typically reach 150,000-200,000 miles before requiring major overhaul or replacement. OM656 straight-six diesels and M256 mild-hybrid petrol units show improved longevity over earlier OM642 and M276 designs when serviced to manufacturer schedules.

Key points

• Regular oil changes with MB 229.51 spec fluid prevent premature wear
• Timing chain inspection recommended at 80,000 miles on OM642 units
• AdBlue system servicing prevents start-prevention faults on OM656 engines
• Rebuilt engines with upgraded components can exceed original lifespan expectations

Enquire about long-warranty Mercedes-Benz GLS rebuilt engine options

Question 8

What are the warning signs my Mercedes-Benz GLS needs an engine replacement?

Key indicators that your Mercedes-Benz GLS requires engine replacement include persistent cold-start rattling, blue exhaust smoke, low oil pressure warnings, and repeated limp mode activation. These symptoms often signal internal wear beyond economical repair on OM642 and M276 engines.

Key points

• Cold-start metallic rattling suggests OM642 timing chain tensioner failure
• Blue smoke indicates piston ring or turbo seal degradation requiring rebuild
• Low oil pressure warnings often precede catastrophic bearing failure
• Repeated AdBlue faults on OM656 may mask deeper combustion issues

Get urgent quotes for Mercedes-Benz GLS engine replacement from UK specialists

Question 9

Do Mercedes-Benz GLS replacement engines come with a warranty?

Yes, every rebuilt Mercedes-Benz GLS engine supplied through EngineMarket includes a minimum 12-month unlimited mileage warranty covering internal mechanical components. Specialist rebuilders often offer extended 24-month coverage on premium units like OM656 and M177 engines.

Key points

• 12-month unlimited mileage warranty is standard across our specialist network
• Coverage includes internal components, gaskets and seals post-installation
• Extended 24-month options available for OM656 and AMG M177 units
• Warranty terms vary by supplier; always confirm exact coverage before purchase

Compare warranty terms for Mercedes-Benz GLS replacement engines from UK suppliers

Question 10

How do I find the engine code on my Mercedes-Benz GLS?

The engine code on your Mercedes-Benz GLS appears on the engine block stamping, vehicle registration document (V5C), and under the bonnet on the emissions compliance plate. OM642, OM656, M256 and M177 are the most common codes across X164, X166 and X167 generations.

Key points

• V5C registration document lists engine code in section D.2
• Emissions plate under bonnet displays code format like "OM642.826"
• Engine block stamping visible near oil filter housing on most variants
• Registration lookup instantly identifies exact engine code and compatible replacements

Enter your registration to identify your Mercedes-Benz GLS engine code and get quotes

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Why UK Mercedes-Benz GLS Owners Trust EngineMarket

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Mercedes-Benz GLS Engine ReplacementAll Variants Covered

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All Mercedes-Benz GLS Variants - Engine Replacement Coverage

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Mercedes-Benz GLS Engine ProblemsWhat It Costs to Fix & When Replacement Makes Sense

Don't Let Engine Failure Write Off Your Mercedes-Benz GLS

Mercedes-Benz GLS Engine ProblemsWhat It Costs to Fix & When Replacement Makes Sense

Don't Let Engine Failure Write Off Your Mercedes-Benz GLS

Mercedes-Benz GLS Engine TypesOptions, Costs & What to Expect

Mercedes-Benz GLS Engines by SizeFind the Right Displacement for Your Variant

Mercedes-Benz GLS Engines by Fuel Type

Mercedes-Benz GLS Engines by YearWhat Was Fitted & When

Mercedes-Benz GLS Engine ReplacementFrequently Asked Questions

How much does it cost to replace a Mercedes-Benz GLS engine in the UK?

Is it worth replacing the engine on a Mercedes-Benz GLS?

Which Mercedes-Benz GLS engine is most reliable?

What causes Mercedes-Benz GLS OM642 engine failure?

Can I swap a GLS 350d engine for a 400d unit?

Should I choose petrol or diesel for a Mercedes-Benz GLS replacement?

How long should a Mercedes-Benz GLS engine last?

What are the warning signs my Mercedes-Benz GLS needs an engine replacement?

Do Mercedes-Benz GLS replacement engines come with a warranty?

How do I find the engine code on my Mercedes-Benz GLS?

Why UK Mercedes-Benz GLS Owners Trust EngineMarket

Compare Mercedes Benz GLS engine prices with vetted UK specialists

Compare engine prices for Mercedes Benz GLS in the UK and get competitive quotes from garages near you.

Mercedes-Benz GLS Engine Problems
What It Costs to Fix & When Replacement Makes Sense

Mercedes-Benz GLS Engine Problems
What It Costs to Fix & When Replacement Makes Sense