G Class Diesel Engines
from £4,995 to £9,500
Rebuilt units from £4,995 · Common codes: OM642.DE30.LA, OM642.LS, OM656, OM603
Mercedes Benz ENGINE MARKETPLACE
Mercedes G Class M176/OM642/M177 Specialist Engine Replacement - Compare Quotes
Get specialist quotes from UK Mercedes G Class engine experts. Compare reconditioned & rebuilt engines for G 350 to G 63 AMG - M176/OM642/M177 covered. Get specialist quotes for your G Class.
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G Class Petrol Engines
from £5,500 to £12,000
Rebuilt units from £5,500 · Common codes: M176, M177, M113, M117
G Class AMG Engines
from £7,500 to £25,000
Rebuilt units from £7,500 · Common codes: M157, M177 (G63), M279 (G65)
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Compare reconditioned, rebuilt & used engine prices
Supply & fit available - parts and labour from vetted specialistsInstant engine replacement quote - 100% free, no obligationEngine replacement near me - UK-wide specialist networkCompare reconditioned, rebuilt & used engine pricesSupply & fit available - parts and labour from vetted specialistsHow It Works
3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz G Class Replacement Engineto Finding the Best Mercedes Benz G Class Replacement Engine
12-Month Warranty
Supply & Fit Available
Nationwide Delivery
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Most replacements completed within 3-5 days.
Live UK Engine Market Data
What Are UK Drivers Paying for Mercedes Benz G Class Engine Replacement
The table below shows typical UK rebuilt engine replacement costs across different Mercedes Benz G Class variants, covering known failure causes, engine codes, fuel types and engine sizes.
Average Market Prices
↻ Last updated: 4 Aug 26, 9:26
Customer Reviews
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Variants We Cover
Mercedes Benz G Class Engine ReplacementAll Variants Covered
Mercedes Benz G Class G 350 d
OM642 3.0L Diesel
Rebuilt Engines: £4,800-£7,500
Mercedes Benz G Class G 400 d
OM656 3.0L Diesel
Rebuilt Engines: £5,500-£8,500
Mercedes Benz G Class G 350 CDI
OM642 3.0L Diesel
Rebuilt Engines: £4,500-£7,200
Mercedes Benz G Class G 320
M112 3.2L Petrol
Rebuilt Engines: £3,800-£6,000
G Class
Engine Codes
Mercedes Benz G Class Engine CodesFull Technical Specifications & Replacement Guide
Every engine code fitted to the Mercedes Benz G Class 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 G Class variants.
OM642 DE30 LA - 3.0L Diesel
Main replacement triggers are timing chain wear, EGR / cooling faults and turbo-control issues.
Compatible variants
G 320 CDIG 350 CDIG 350 CDI EditionG 350 dG 350 d ProfessionalG 350 BlueTEC
Avg. rebuilt price
£4,500 - £7,500
Supply only
Technical specifications
- Fuel type
- Diesel
- Engine size
- 3.0L
- Power output
- 224-245 hp
- Years fitted
- 2006-2023
Common failures
- ●Main replacement triggers are timing chain wear, EGR / cooling faults and turbo-control issues.
- ●Confirm exact engine code and fitment before ordering.
- ●Ask for warranty and supply & fit terms.
Not sure which engine code?
G Class
Common Problems
Mercedes Benz G Class Engine Problems - What It Costs to Fix & When Replacement Makes Sense
OM642 Oil Cooler Seal Failure - Why G Class Diesel Engines Leak Oil Excessively
OM642 Oil Cooler Seal Failure
Most affected vehicles
Mercedes Benz G Class G 320 CDIG 350 CDI
Mercedes Benz G Class G 320 CDI, G 350 CDI, G 350 d (2006-2023, OM642 DE30 LA & OM642 LS)
Failure mileage range
60,000 - 90,000 miles
Typical failure window
Root cause
Repair options & estimated costs (UK ranges)
| Repair tier | Dealer price | Specialist price | What it involves | Longevity / suitability |
|---|---|---|---|---|
| Minor - Seal Replacement | £1,800 - £2,500 | £900 - £1,400 | Replace oil cooler seals (A6421800003 revised part), flush cooling system, new oil and filter | 60k-80k miles if using revised Viton seals |
| Intermediate - Oil Cooler & Seal Assembly | £2,500 - £3,500 | £1,400 - £2,000 | Replace complete oil cooler unit with revised seals, coolant flush, thermostat inspection | 80k-100k miles; recommended if cooler shows corrosion |
| Full Replacement - Rebuilt Engine | £7,500 - £10,000 | £4,800 - £7,500 | Supply & fit rebuilt OM642 with upgraded seals, new oil pump chain, turbo inspected | 100k+ miles with extended warranty cover |
Our recommendation
If caught early with only external weeping, the seal-only specialist fix at £900-£1,400 is excellent value and should last 60k+ miles with revised seals. However, if the leak has caused coolant contamination or the engine has overheated, we recommend the full rebuilt route - contaminated oil galleries often cause turbo or bearing failure within 10k-15k miles of a partial repair.
Compare rebuilt OM642 engine prices for your Mercedes Benz G ClassReplacement Engine Options
Mercedes Benz G Class Engine TypesOptions, Costs & What to Expect
Every engine type for your Mercedes Benz G Class is available through our UK network, with typical price ranges based on variant, engine code and budget.
Mercedes Benz G Class Reconditioned Engines (Recon)£4,500 - £9,500((supply only))
Mercedes Benz G Class Rebuilt Engines£3,800 - £8,500((supply only))
Mercedes Benz G Class Used Engines£2,000 - £5,500((supply only))
Mercedes Benz G Class Remanufactured Engines£6,500 - £15,000((supply only))
Mercedes Benz G Class Refurbished Engines£2,800 - £6,000((supply only))
Compare Mercedes Benz G Class engine prices with vetted UK suppliers
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 G Class within hours.
Engine Sizes
Mercedes Benz G Class Engines by SizeFind the Right Displacement for Your Variant
Every displacement fitted to the Mercedes Benz G Class across all generations is listed below, with compatible engine codes, production years and common failure notes.
The 2.9-litre inline-six diesel arrived with the W463A generation G Class in 2019, replacing the long-serving OM642 V6. Codenamed OM656, this all-alloy unit introduced CAMTRONIC variable valve lift on the exhaust side and a two-stage turbocharger system producing exceptional 700Nm torque delivery from just 1,200rpm . Available initially as the G 400 d, the 2.9L later expanded to G 450 d variants, offering the most powerful diesel ever fitted to a G Class with 243kW output while maintaining refinement that eliminates traditional diesel clatter .
⚙
Engine Code(s)
OM656 D29, OM656
▣
Compatible Models (UK)
G 400 d (2019-present), G 450 d
ϟ
Power output
Verified by registration
△
Common Failure Points
CAMTRONIC actuator seizure (A6560500001), coolant pump seal failure, AdBlue dosing module crystallisation on urban-driven vehicles
Production Years: 2024-present
Get quotes for Mercedes Benz G Class 2.9L diesel enginesMercedes Benz G Class Engines Fuel Type
Mercedes Benz G Class Engines by Fuel Type
Mercedes Benz G Class Diesel Engines
DieselThe backbone of UK G Class sales since the W463 generation, diesel engines dominate replacement enquiries - particularly the OM642 V6 which powers approximately 70% of diesel models on British roads.
Common Mercedes Benz G Class Diesel Engine Families
- •OM642 - 3.0L V6, the most searched replacement engine (G 320 CDI, G 350 CDI, G 350 d), oil cooler seal failure risk
- •OM656 - 3.0L inline-6, current-generation diesel (G 400 d, G 450 d), CAMTRONIC actuator and AdBlue issues
- •OM603 - 3.0L naturally aspirated inline-6, classic G 300 GD, legendary durability but injector pump calibration drift
Found In
- •W460/W461 (1979-1990) - OM617 (G 300 GD military/civilian)
- •W463 Early (1990-2006) - OM603 (G 300 GD), OM606 (G 300 Turbodiesel)
- •W463 Facelift (2006-2018) - OM642 (G 320 CDI, G 350 CDI, G 350 d)
Known For
- •Exceptional low-range torque suited to G Class off-road capability
- •OM642 oil cooler seal failure affecting ~80% of units over 60k miles
- •High replacement demand on G 350 d (most common UK fleet variant)
1 of 3
Mercedes Benz G Class Diesel Engines
DieselThe backbone of UK G Class sales since the W463 generation, diesel engines dominate replacement enquiries - particularly the OM642 V6 which powers approximately 70% of diesel models on British roads.
Common Mercedes Benz G Class Diesel Engine Families
- •OM642 - 3.0L V6, the most searched replacement engine (G 320 CDI, G 350 CDI, G 350 d), oil cooler seal failure risk
- •OM656 - 3.0L inline-6, current-generation diesel (G 400 d, G 450 d), CAMTRONIC actuator and AdBlue issues
- •OM603 - 3.0L naturally aspirated inline-6, classic G 300 GD, legendary durability but injector pump calibration drift
Found In
- •W460/W461 (1979-1990) - OM617 (G 300 GD military/civilian)
- •W463 Early (1990-2006) - OM603 (G 300 GD), OM606 (G 300 Turbodiesel)
- •W463 Facelift (2006-2018) - OM642 (G 320 CDI, G 350 CDI, G 350 d)
Known For
- •Exceptional low-range torque suited to G Class off-road capability
- •OM642 oil cooler seal failure affecting ~80% of units over 60k miles
- •High replacement demand on G 350 d (most common UK fleet variant)
Mercedes Benz G Class Petrol Engines
PetrolFrom the durable M113 V8 to the fire-breathing M177 biturbo, G Class petrol engines span three decades of Mercedes performance engineering - with AMG variants commanding premium replacement costs.
Common Mercedes Benz G Class Petrol Engine Families
- •M176 - 4.0L biturbo V8 (G 500 2015-present), cylinder deactivation, exhaust manifold cracking risk
- •M177 - 4.0L biturbo V8 AMG (G 63 AMG 2018-present), hand-built, 585 hp, top timing chain wear
- •M157 - 5.5L biturbo V8 AMG (G 63 AMG 2012-2018), turbo actuator failure common
Found In
- •W460/W463 Early (1981-1992) - M117 (G 500, G 560 GE classic)
- •W463 Facelift (1998-2018) - M112 (G 320), M113 (G 500), M113K (G 55 AMG), M157 (G 63 AMG)
- •W463A (2018-present) - M176 (G 500), M177 (G 63 AMG)
Known For
- •AMG variants represent highest-value replacement enquiries (£7,500-£25,000)
- •M113 timing chain tensioner wear causing cold-start rattle on 80k-120k mile units
- •M157/M177 hot-V design concentrates heat, leading to manifold cracking
Mercedes Benz G Class Mild Hybrid (MHEV) Engines
MHEVThe G 450 d introduced a 48-volt mild hybrid system to the diesel range in 2024, adding electric assistance without plug-in capability.
Mercedes Benz G Class MHEV Engine Codes
- •OM656 - 3.0L inline-6 diesel with integrated starter-generator (ISG)
- •48-volt belt-driven starter-generator recovers braking energy
- •Provides up to 20 hp electric boost under acceleration
Found In
- •G 450 d (2024-present) with OM656 diesel engine
Important Notes
- •48-volt system adds complexity but does not affect engine replacement pricing significantly
- •Battery health check recommended during engine swap
- •No plug-in hybrid or full EV G Class exists for UK market (EQG expected future)
Not sure which fuel type your Mercedes Benz G Class 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 G Class specialists.
Engine YearsGet quotes for 1979-1989 Mercedes-Benz G-Class replacement engines →
Mercedes Benz G Class Engines by YearWhat Was Fitted & WhenMercedes Benz G Class Engines by Year - What Was Fitted & When
From the 1979 W460 military-spec original to the 2024 electrified W465 generation, this timeline covers every major engine fitted to the Mercedes-Benz G-Class - helping you identify your exact unit and compare rebuilt prices from UK specialists.
⚙Key Changes
- ✓W460 launch with short-wheelbase (SWB) cabrio, SWB station wagon, long-wheelbase (LWB) station wagon body styles
- ✓230 G (2.3L petrol) and 240 GD (2.4L diesel) as initial UK options
- ✓Military-spec W461 continued alongside civilian W460 from mid-1980s
- ✓Solid axles, ladder-frame chassis and three differential locks established
▣Main Engines
M115- 2.0L petrol (200 G) - entry-level
M115- 2.3L petrol (230 G) - most common early petrol
OM616- 2.4L diesel (240 GD) - four-cylinder workhorse
OM617- 3.0L diesel (300 GD) - five-cylinder, legendary durability
▰Popular Models
- •Mercedes-Benz 230 G · Mercedes-Benz 240 GD · Mercedes-Benz 300 GD
🔧Known For
- ✓Built for military durability, not luxury or speed
- ✓OM617 diesel regularly exceeds 300,000 miles with basic maintenance
- ✓Slow, noisy, but virtually unbreakable
- ✓300 GD remains highly sought after for classic restoration projects
Engine Codes Covered:
M115OM616OM617Not sure which year your Mercedes-Benz G-Class 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 G-Class specialists.
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