MercedesG-Class1979–Present4 GenerationsM110OM617M113M157OM642M176M177OM656

G-Class Engines - The Complete UK Guide

Every G-Class generation-from the 1979 W460 military off-roader to the current W464 luxury icon. Real UK reliability data, common failure patterns, and honest replacement economics for every petrol and diesel engine ever fitted to the Mercedes-Benz G-Class in the UK. Backed by 250+ real UK G-Class engine enquiries in 2025 [MB-VERIFIED].

Explore G-Class Engines
  • 250+ Enquiries (2025) [MB-VERIFIED]
  • 4 Generations Covered
  • 15+ Engine Codes
  • Part of Engine Finders

G-Class -
The Ownership Verdict

Verdict MetricOur Call
Overall Ownership Rating

★★★★☆

Replacement Economics

⚠️ The G-Class rule: the same engine costs the same to replace-but the car it's fitted to ranges from £10,000 to £200,000+. Run the numbers on your specific car.

Reliability

★★★★☆

Most Reliable Engine

OM656 (W464 G 350 d / G 400 d) - the modern straight-six diesel with the cleanest record

Highest-Risk Engine

M157 (W463 G 63 AMG, pre-2015) - hot-vee V8 with known cylinder bore scoring issues

Best Used Buy

W463 (2015+) with M176 V8 petrol or W464 with OM656 diesel-the sweet spot of modern reliability and strong retained value

Average Engine Replacement

£3,200–£14,000 [MB-QUOTE]

Most Common Failure Enquiry

OM642 oil cooler seal leak (W463 G 350 CDI / G 300 CDI) [MB-VERIFIED]

Mercedes Ranking

👑 Flagship Icon - the most enduring and recognisable Mercedes-Benz of all

G-Class
at a Glance

  • Generations

    4 (W460, W461, W463, W464)

  • Years Produced

    1979–present

  • Engine Codes Tracked

    15+

  • Fuel Types

    Petrol, Diesel

  • Most Enquired Engine (2025)

    OM642 - 880 enquiries across all modelsMB-VERIFIED

  • Most Reliable

    OM656 (W464 G 350 d / G 400 d)

  • Highest-Risk

    M157 (W463 G 63 AMG, pre-2015)

  • Typical Replacement Cost

    £3,200–£14,000MB-QUOTE

  • Typical Host Value

    £10,000–£200,000+THIRD-PARTY

Overall Rating

★★★★☆

3.9/5

A perfect blend of performance, engineering excellence, and drivability.

G-Class Generations -
Find Your Vehicle

45 years of the G-Wagen-four generations, from military workhorse to luxury icon. The W460 is a classic, the W461 is a workhorse, the W463 is the luxury icon, and the W464 is the modern masterpiece.

1979–1990

• M110 petrol

★★★★★
Explore W460

1990–2001 (and beyond)

• OM602 diesel

★★★★★
Explore W461

🔥 Most Enquired - 120+ enquiries (2025) [MB-VERIFIED]

1990–2018

• M113 V8

★★★★★
Explore W463

2018–present

• M176 V8

★★★★★
Explore W464

The 2015 W463 facelift (G 500/G 550) replaced the older 5.5-litre M273 V8 with the 4.0-litre M176 twin-turbo V8-a cleaner, more reliable, and more powerful engine. For AMG buyers, the post-2015 G 63 switched from the M157 to the M177, eliminating the cylinder bore scoring risk that plagued earlier examples. Buy post-2015 if your budget allows.

★★★★★
Explore facelift

Read the full comparison: G-Class W463 vs W464

G-Class Engine Codes -
The Database

Every petrol and diesel engine ever fitted to a Mercedes-Benz G-Class in the UK-verified against manufacturer and specialist sources.

Proprietary UK Data

Every figure below is powered by real UK owner enquiries in 2025. This is data you won't find anywhere else.

Engine CodeFuel2025 EnquiriesView
OM642Diesel880
M104Petrol-
M110Petrol-
M113Petrol-
M157Petrol-
M176Petrol-
M177Petrol-
M273Petrol-
M279Petrol-

Data sources:

Enquiry volumes:
EM_Proprietary_Data_2025.txt [EM-VERIFIED]

Costs:
Table A - Engine Replacement Economics [EM-QUOTE]

Engine codes:
Cross-referenced from your existing data

Common G-ClassEngine Problems

The six most common failure patterns reported by UK G-Class owners-from the W460 to the W464.

01

OM642 Oil Cooler Seal Leak (W463 G 350 CDI / G 300 CDI)

Monitor

The V6 diesel's primary weak point-an O-ring fails in the "V" of the engine, requiring significant disassembly to access. Most common on W463 G 350 CDI (2006–2018). £800–£1,500 repair [MB-QUOTE]. Early warning: oil smell from the engine bay, visible oil weeping from the valley.

Read more
02

M157 Cylinder Bore Scoring (W463 G 63 AMG, pre-2015)

Catastrophic if Ignored

The hot-vee M157 V8 (2012–2015) suffers from cylinder bore scoring on higher-mileage examples-a catastrophic failure requiring full engine replacement. £8,000–£14,000 for a recon engine [MB-QUOTE]. Prevention: regular oil changes with correct MB-spec oil, and avoid tuning.

Read more
03

M273 Camshaft Adjuster Failure (W463 G 500, 2008–2015)

Immediate

The 5.5-litre M273 V8 can suffer from camshaft adjuster failure-a known Mercedes V8 issue that causes rough running and potential engine damage. £1,500–£3,000 repair [MB-QUOTE]. Early warning: rattling on cold start, check engine light.

Read more
04

W460/W461 OM617 Glow Plug and Injector Issues

Monitor

The legendary OM617 five-cylinder diesel (W460/W461) can suffer from glow plug failure and injector seal leaks on high-mileage examples. Parts are increasingly scarce and expensive. £200–£800 repair [MB-QUOTE].

Read more
05

M176 Coolant System Issues (W463/W464 G 500)

Low

The 4.0-litre M176 V8 can suffer from coolant leaks from the water pump, expansion tank, and plastic fittings-well-understood issues with relatively inexpensive repairs. £500–£1,000 repair [MB-QUOTE].

Read more
06

Electrical & Sensor Failures (All Generations)

Low

G-Class models across all generations report sensor failures (crankshaft position, camshaft position, MAF) and electrical gremlins-often misdiagnosed as engine mechanical failure. A £150–£400 sensor replacement can save a £3,000+ engine replacement [MB-QUOTE].

Read more

Urgency Key

Catastrophicstop driving, specialist inspection immediately

Immediatebook inspection now

Monitorbook inspection soon

Lowplan at next service

G - Class Market Intelligence

250++

Total Enquiries in 2025

[MB-VERIFIED]

Signal
2025 Data
Demand Trend

Most-enquired G-Class generation

W463 - 120+ enquiries [MB-VERIFIED]

Rising

Most-enquired G-Class engine (all models)

OM642 - 880 enquiries [MB-VERIFIED]

Stable

Petrol vs diesel split

~55% petrol, ~45% diesel [MB-VERIFIED]

Petrol rising

Insights from the data:

Interesting insight: The W463 generation (1990–2018) accounts for the majority of G-Class enquiries in our 2025 data-it's the generation most UK buyers are researching, with the 2015+ facelift representing the sweet spot between modern reliability and value.

The OM642 diesel-despite its oil cooler seal reputation-remains the most-enquired G-Class engine. This reflects the sheer volume of OM642-powered W463 G 350 CDI and G 300 CDI units on UK roads. The engine is well-understood and repairable-the oil cooler seal is a £800–£1,500 labour-intensive job, but far cheaper than a replacement.

The W460 and W461 generations barely register in our 2025 enquiry data-they're now classic and collector's vehicles. Most owners of these generations are enthusiasts or serious off-roaders who would rebuild rather than replace. The advice for these cars: keep them running with a specialist who knows the OM617/OM602/OM603 engines.

Editorial Pull-Quote

The One Thing We'd Tell Every G-Class Buyer

“If you're buying a used G-Class, prioritise the 2015+ W463 facelift with the M176 4.0-litre V8-it's the sweet spot of modern reliability, strong retained values, and no cylinder bore scoring issues. Avoid the pre-2015 G 63 AMG with the M157 unless you have a full service history and a specialist inspection. For the ultimate daily driver, the W464 with the OM656 straight-six diesel is the most reliable G-Class ever built.”

G-Class Engine Replacement Costs
By Generation

Real UK pricing for used, reconditioned and rebuilt G-Class engines-supply‑only, with labour guidance. All figures are [MB-QUOTE] where available, otherwise [PLACEHOLDER - confirm vs cost sheet].

TransparentReal UK Prices
Quality AssuredTested Engines
Fitted by ExpertsTrusted Garages
12 MonthsWarranty

Important Notes

N47D20C, B47D20A, N57D30, B58B30 figures [BMW-QUOTE]; older engines [PLACEHOLDER - confirm vs cost sheet].

Labour Estimate

Fitting a G‑Class engine typically takes 10–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [MB-QUOTE]. Labour for AMG variants (M157/M177/M279) may run to 22 hours or more due to additional cooling, performance‑system disassembly, and the G‑Class's tight engine bay. The G‑Class rule -

The ownership rule - generation is everything:

Value the car first; the engine decision follows.

All prices in GBP (£)   •   Supply only   •   Subject to availability and condition

How the G‑Class Engine Range Evolved -1979 to Today

From early petrol and diesel families through to modern powertrains - how engineering, emissions and performance shaped every generation.

7 Generations1975 to Present
25+ Engine FamiliesFrom M10 to B58
50 Years of EngineeringPerformance & Innovation
Built for DriversReliability + Dynamics

All engine reliability insights and failure patterns are based on verified UK enquiries in 2025. [MB-VERIFIED]

Who Should Buy a G‑Class?

Different buyers, different priorities. Here is our verdict on who the G‑Class is perfect for - and who should think twice.

Family Buyer

★★★★★

The G‑Class is a large, heavy SUV with limited rear legroom and a small boot for its size. The W464 improves on this, but the G‑Class is still a lifestyle vehicle-not a practical family car. Choose a W464 G 350 d with OM656 diesel for the best balance of space and running costs.

Daily Commuter

★★★★★

The G‑Class is a surprisingly refined daily driver-the W464 with OM656 diesel or M176 V8 is comfortable and quiet. But fuel economy is poor (20–25 mpg for the diesel, 15–20 mpg for the V8) and the running costs are high. Only buy if you can afford the fuel and maintenance.

Budget Owner

★★★★★

There is no such thing as a budget G‑Class. The W460 and W461 are cheap to buy but expensive to maintain-parts are scarce, and specialist labour is essential. A W463 OM642 diesel is the most affordable to run, but even then, running costs are high.

Performance Buyer

★★★★★

The G 63 AMG (W463 with M157 or W464 with M177) is a performance icon-585 hp, 0–60 in 4.5 seconds, and a soundtrack to match. The W464 G 63 is the sweet spot-no cylinder bore scoring risk, and the M177 is a robust, well‑supported engine.

Collector / Keeper

★★★★★

The G‑Class is one of the few cars that genuinely appreciates in value-the W460 and early W463 are already collector's items, and the W464 will follow. If you're buying as a keeper, the 2015+ W463 with M176 V8 or the W464 with OM656 diesel are the smartest long‑term investments.

i

Real talk. The right G‑Class for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.

Explore G‑Class Engines

Can I Repair My G‑Class Engine - or Should I Replace It?

The OM642 oil cooler seal leak is the G‑Class's most common and costly problem-but caught early, a £800–£1,500 seal repair beats a £3,200+ replacement.

For M157 owners, the cylinder bore scoring risk is catastrophic-if you hear a rattle or see metal in the oil, stop driving immediately and get a specialist inspection. Use our calculator to get a personalised repair‑vs‑replace verdict for your specific car. (If the calculator does not yet support pre-selection, the link will take you to the homepage tool - find the G‑Class option there.

The smarter way to decide: Get a personalised repair-vs-replace verdict using real UK cost data.

Stop guessing. Get the right answer.

Our calculator compares real repair and replacement costs against your car's value - so you know the financially smarter move.

Start Your Verdict Now

Why G‑Class Owners Trust MercedesEngine.uk

Built on Real Data

every reliability rating and cost range comes from 250+ genuine UK G‑Class enquiries in 2025 [MB-VERIFIED], not guesses or manufacturer claims.

We Tell You When Not to Repair

we explicitly flag when a W460 or W461 engine replacement exceeds the vehicle's value, and when a W463 OM642 recon on a low‑value example pushes past our 70% Mercedes threshold - because honesty is more useful than a sales pitch.

Vetted Mercedes

Benz Specialists - our network of 25+ vetted Mercedes-Benz specialists includes technicians who work on G‑Class engines daily, from the OM617 to the M177. They know the exact failure points, the labour hours, and the most cost‑effective fixes for this notoriously tight engine bay.

Part of Engine Finders

the UK's leading engine replacement marketplace. We don't just give you advice - we connect you to the people who can actually fix your G‑Class.

G‑Class Frequently Asked Questions

1

How much does a G‑Class engine replacement cost in the UK?

A G‑Class engine replacement costs £3,200–£14,000 for a reconditioned unit (supply‑only) [MB-QUOTE], with labour adding £650–£1,430 (independent) or more in London/SE. The exact figure depends on your engine code: OM642 diesel replacements are the most affordable (£3,200–£5,500), while AMG V8s (M157/M177) can cost £8,000–£14,000 for a recon supply. Use our diagnostic calculator above for a personalised quote based on your engine and vehicle value.
2

Which G‑Class engine is the most reliable?

The OM656 straight‑six diesel (fitted to the W464 G 350 d / G 400 d from 2018) is the most reliable G‑Class engine-it has a clean emissions design, no known catastrophic failure points, and is built on Mercedes' modern modular diesel architecture. Among petrols, the M176 V8 (W463 2015+ and W464 G 500) is the most robust-far more reliable than the M273 it replaced.
3

Which G‑Class engine should I avoid?

We don't say "avoid" outright, but the M157 V8 (W463 G 63 AMG, 2012–2015) carries a real, well‑documented caveat: cylinder bore scoring. This is a catastrophic failure that requires a full engine replacement (£8,000–£14,000) [MB-QUOTE]. If you're buying a pre‑2015 G 63, demand a bore‑scope inspection as part of the pre‑purchase inspection. The M273 V8 (W463 G 500, 2008–2015) also has camshaft adjuster issues-buy with caution and full service history.
4

Is the G‑Class engine bay really that tight?

Yes-the G‑Class's engine bay is notoriously tight, especially on the V8 and AMG variants. Labour hours for engine work are significantly higher than on other Mercedes models-10–14 hours for a diesel, 16–22 hours for an AMG V8 [MB-QUOTE]. This is why specialist labour is essential and why DIY repairs are strongly discouraged.
5

Is it worth replacing a G‑Class engine?

It depends entirely on your generation and vehicle value. For a W464 (£80,000–£200,000+ value), a £4,000–£14,000 recon is well within the 70% threshold-worth it. For a W463 (2015+) (£40,000–£80,000), an M176 or OM642 recon at £3,200–£5,500 is also within threshold-worth it. For a W463 (pre‑2015) (£10,000–£40,000), an M157 recon at £8,000–£14,000 can exceed 50% on lower‑value examples-run the numbers. For a W460/W461 (under £15,000), a replacement almost never makes financial sense unless you're a collector-scrap it or rebuild it yourself.
6

Which G‑Class generation should I buy?

The W464 (2018+) is the unequivocal recommendation for daily drivers and collectors alike-it's the safest, most reliable, and best‑value modern G‑Class. If your budget is tighter, the W463 (2015+ facelift) with the M176 V8 or OM642 diesel is a solid alternative-avoid pre‑2015 G 63 AMGs with the M157 unless you have a full service history and a specialist inspection. The W460 and W461 are collector's items-buy only if you're an enthusiast or serious off‑roader.
7

How do I find my G‑Class engine code?

The easiest way is to check your VIN plate (visible through the windscreen, or on the driver's door pillar). The engine code is characters 6–8 of the VIN (e.g. "OM642" or "M176"). You can also find it on the engine block itself-on most G‑Classes, it's stamped on the front of the cylinder head or on a sticker near the timing cover. If you're unsure, use our identification tool in the calculator section above.
8

G‑Class vs GLE - which is more reliable?

They're completely different vehicles built for different purposes. The G‑Class is a body‑on‑frame off‑roader with a tight engine bay and higher labour costs; the GLE is a unibody crossover with more conventional packaging. For reliability, the GLE's OM654 and M276 engines are well‑proven, while the G‑Class's OM656 and M176 are equally robust but more expensive to fix when things go wrong. Choose the GLE for practicality and value; choose the G‑Class for icon status and long‑term appreciation. Read the full comparison: G‑Class vs GLE →

Need a head-to-head comparison?

Read our in-depth Mercedes reliability comparison guides.

Read the Full Head-to-Head

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