Mercedes M-Class W164 Engines — The Complete UK Guide
Every engine fitted to the W164 SUV — from the OM642 V6 diesel to the M272 and M273 V6/V8 petrols, and the fire-breathing M156 V8 in the ML 63 AMG. Real UK replacement costs, honest failure data, and the balance-shaft issues that still haunt early V6-powered cars. Backed by real UK W164 enquiries in 2025 [MB-VERIFIED].
Explore W164 Engines
Mercedes M-Class W164 Engine Codes — The Complete Database
Every engine fitted to the W164 SUV specifically — from the entry-level V6 diesel to the naturally aspirated V8 in the ML 63 AMG.
Overview
Mercedes M-Class W164 — Overview
The W164 is the second-generation M-Class, launched in January 2005 at the North American International Auto Show in Detroit.
Built at the US plant in Tuscaloosa, Alabama, it replaced the W163 and introduced a unibody construction instead of the ladder-type frame used previously. The engine range spans the OM642 V6 diesel in two output levels, the M272 V6 petrol, the M113 and M273 V8 petrols, the M156 V8 in the ML 63 AMG, and the OM629 V8 diesel. A 2008 facelift brought revised styling, interior updates, and mechanical improvements.
Key Facts
Platform
Mercedes W164 (unibody, shared with GL-Class X164)
Predecessor
W163
Successor
W166
Sibling platform
GL-Class (X164)
Market Intelligence
The W164 M-Class generated real UK engine enquiries in 2025 [MB-VERIFIED], concentrated on the OM642 diesel and M272 petrol as these cars enter enthusiast-owner territory.
Best & Worst Engines
Best Diesel Overall
OM642.940 (ML 320 CDI, 2005–2009)
“The 3.0-litre V6 diesel OM642 delivers 224 hp with 510 Nm of torque, combining strong performance with reasonable economy. It's a robust, proven engine that regularly exceeds 200,000 miles with proper maintenance — though oil cooler seal leaks are a known issue. The ML 350 BlueTEC (OM642.820) from 2009 onwards is equally refined.”
Who it's for: buyers who want the best combination of performance, economy and reliability in the W164 range.
Best Petrol Overall
M113.964 (ML 500, 5.0-litre V8)
“The 5.0-litre M113 V8 is one of the most bulletproof petrol engines Mercedes ever built — 306 hp of smooth, naturally aspirated power, no balance-shaft issues, no timing-chain worries. It's the W164's sleeper pick — a V8 that sounds wonderful and keeps going.”
Who it's for: buyers who want V8 refinement without the M273's balance-shaft risk.
Highest Risk
M272.967 (ML 350, 3.5-litre V6)
“The M272 V6 is a great engine — but early units (2005–2008) suffer from a well-documented balance shaft gear failure. The teeth wear away, causing the timing to jump and potentially destroying the engine. If your engine serial number starts with '272', check whether it's in the affected range. The ML 500 with M113 V8 and diesel models were NOT affected.”
Who it's for: buyers willing to check engine numbers and budget for balance shaft replacement, or those buying post-2008 examples.
Most Expensive Failure
M156.980 (ML 63 AMG, 6.2-litre V8)
“The 6.2-litre M156 V8 is a masterpiece — 510 hp of naturally aspirated AMG thunder, at the time the world's most powerful naturally aspirated 8-cylinder standard-production engine. But when it fails, it fails expensively. Camshaft adjusters, lifters, and the sheer cost of AMG-specific parts mean replacement bills frequently hit five figures.”
Who it's for: collectors and enthusiasts with deep pockets.
Best Value
OM642.940 (ML 280 CDI, 2005–2009)
“The ML 280 CDI offers 190 hp with the same robust OM642 V6 diesel as the more powerful ML 320 CDI. It's cheaper to buy, cheaper to insure, and cheaper to replace than the petrol alternatives — the sweet spot in the W164 diesel range for most UK buyers.”
Who it's for: buyers who want diesel economy and reliability without the V8's fuel consumption.
Most Overlooked
OM629.912 (ML 420 CDI, 4.0-litre V8 diesel)
“The 4.0-litre V8 diesel is rare in the W164 — 260 hp and an effortless 560 Nm of torque. It's the ultimate W164 for long-distance towing, offering V8 refinement with diesel economy. But it's a specialist engine — parts are harder to find and labour is more intensive than the V6 diesel.”
Who it's for: buyers who need serious towing capability and are prepared for specialist maintenance.
Mercedes M-Class W164 — Ownership Economics
The W164 rule
A £3,000–£5,500 OM642 recon against a £5,000 W164 sits at 60–110% of the car's value. On a sub-£4,500 W164, that brushes our 70% Mercedes threshold — we'll honestly tell you to walk away. Against a well-kept £8,000+ example (particularly a V8 or AMG), the same recon drops to a routine 38–69% — a repair decision, not a financial one. Value the car first. For the M156 AMG, the maths is different — if you can afford a £15,000+ ML 63, you can afford the maintenance.
Common Problems
W164 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Model Page's baseline figures — W164 SUV shares its platform with the X164 GL-Class, so costs are inherited directly per the Authority Model, with no divergence note required. M156 AMG costs reflect AMG-specific parts and specialist labour requirements.
Core Variants
Core Variants
Diesel Variants
Scope note: All variants listed are W164 SUV only. X164 GL-Class shares some of these engines but is covered on its own Generation Page, as it features a longer body with third-row seating.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM642.940 (ML 320 CDI) — V6 diesel favourite [PATTERN DATA]
- 2.2. OM642.940 (ML 280 CDI) — volume diesel [PATTERN DATA]
- 3.3. M272.967 (ML 350) — V6 petrol choice [PATTERN DATA]
Most Requested E90 Variants
- 1.1. ML 320 CDI
- 2.2. ML 280 CDI
- 3.3. ML 350 [PATTERN DATA]
Average E90 Replacement Cost
£3,000–£6,500 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. M272/M273 balance shaft (pre-2008)
- 2.2. OM642 oil cooler seal leaks
- 3.3. AIRMATIC air suspension failure [PATTERN DATA]
Mercedes ML 320 CDI W164 (OM642)
6
enquiries
Mercedes ML 350 W164 (M272)
4
enquiries
Mercedes ML 500 W164 (M113)
2
enquiries
FAQ
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UK Engine Replacement Services for W164
covering every variant from ML 280 CDI to ML 63 AMG, with supply-only or full supply & fit available nationwide.
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