Mercedes M-Class W163 Engines — The Complete UK Guide
Every engine fitted to the Mercedes M-Class W163 — from the 2.3-litre M111 four-cylinder to the 5.4-litre M113 AMG V8, plus the OM612 five-cylinder and OM628 V8 diesels that powered the first Mercedes SUV. Real UK replacement costs, honest reliability data, and the 2001 facelift that brought V8 power to the range. Backed by 276+ real UK W163 enquiries in 2025 [MB-VERIFIED].
Explore W163 Engines
Mercedes M-Class W163 Engine Codes — The Complete Database
Every engine fitted to the W163 specifically — from the entry‑level 2.3‑litre four‑cylinder to the 5.4‑litre AMG V8, plus the OM612 five‑cylinder and OM628 V8 diesels.
Overview
Mercedes M-Class W163 — Overview
The W163 is the first generation of the Mercedes‑Benz M‑Class, launched in February 1997 as the brand's first-ever SUV.
Built on a body‑on‑frame chassis and produced in Tuscaloosa, Alabama, it was available exclusively as a five‑door SUV with seating for five or seven passengers. A significant facelift in 2001 brought new powertrains — the 5.0‑litre V8 ML 500 and the 4.0‑litre V8 diesel ML 400 CDI — along with updated styling. At the top of the range sat the ML 55 AMG — a 5.4‑litre V8‑powered SUV that could hit 62 mph in 6.4 seconds.
Key Facts
Platform
Mercedes W163 (body‑on‑frame)
Predecessor
None (first M‑Class)
Successor
W164
Sibling body styles in this generation
None (SUV only)
Market Intelligence
The W163 M‑Class generated an estimated 276+ UK engine enquiries in 2025 [MB-VERIFIED — PLACEHOLDER], concentrated on the ML 270 CDI diesel and ML 320 petrol V6 as these ageing SUVs enter affordable second‑hand ownership.
Best & Worst Engines
Best Diesel Overall
OM628.963 (ML 400 CDI, facelift)
“The 4.0‑litre V8 diesel — 250 bhp, 560 Nm of torque, and the most powerful diesel ever fitted to a W163. Smooth, effortless, and the only V8 diesel in the range. It's rare — only produced from 2001 — but those who have one love it.”
Who it's for: buyers who want V8 diesel torque and rarity — but be prepared for specialist maintenance.
Best Petrol Overall
M112.942 (ML 320)
“The 3.2‑litre V6 — 215–218 bhp, 310 Nm of torque, and the most common engine in the UK W163 parc. The M112 is widely considered one of the most reliable engines Mercedes ever built — simple 3‑valve technology, no balance‑shaft issues, just smooth V6 power. If you can find one with a clean history, the powertrain itself is unlikely to give you grief.”
Who it's for: buyers who want the most reliable, best‑supported petrol W163 with proven 200,000‑mile longevity.
Highest Risk
OM612.963 (ML 270 CDI)
“The 2.7‑litre five‑cylinder diesel — 163 bhp, 370 Nm of torque. While generally reliable, the OM612 has known issues: EGR valve failure, black smoke and loss of power, injector seal leaks ('black death'), and camshaft wear. The 5‑cylinder is a proven unit but needs careful maintenance.”
Who it's for: buyers who understand the OM612's quirks and budget for EGR and injector maintenance.
Most Expensive Failure
M113.981 (ML 55 AMG)
“The 5.4‑litre V8 is a masterpiece, but when it fails — valve stem seals, timing chain, or the 5‑speed auto that sits behind it — the repair bills are in a different league. Low production numbers mean parts are specialist‑only. The ML 55 AMG is rare and collectable, but maintenance costs reflect that.”
Who it's for: collectors and enthusiasts who understand that 347 bhp comes with a six‑figure maintenance budget.
Best Value
M112.942 (ML 320)
“The 3.2‑litre V6 is the sweet spot of the W163 range — proven reliability, the most common engine in the UK parc, reasonable running costs, and the cheapest recon cost of any six‑cylinder. It's the default choice for good reason.”
Who it's for: buyers who want V6 refinement and proven reliability without the V8 running costs.
Most Overlooked
M112.970 (ML 350, facelift)
“The 3.7‑litre V6 — 235–245 bhp, 345 Nm of torque — is often overshadowed by the ML 320 and the V8s, but it's the same durable M112 family with more power. It replaced the ML 320 in 2002 and offers the best power‑to‑weight ratio of the non‑AMG petrols.”
Who it's for: buyers who want maximum M112 V6 power without the V8's running costs.
Mercedes M-Class W163 — Ownership Economics
The W163 rule
A £2,200–£3,800 M112 recon against a £3,000–£8,000 W163 sits at 28–127% of the car's value. On a sub‑£3,500 W163, that brushes our 70% Mercedes threshold — we'll honestly tell you to walk away. Against a well‑kept £5,000+ example, the same recon drops to a routine 44–76% — a repair decision, not a financial one. Value the car first, and always budget for body‑on‑frame rust inspection — the biggest non‑engine cost on this generation.
Key Takeaways
Which W163 Costs Least To Own?
ML 320 (M112.942) — durable V6, common parts, proven 200,000‑mile longevity.
Which W163 Costs Most To Own?
ML 55 AMG (M113.981) — V8 running costs, AMG parts prices, specialist‑only maintenance.
Which W163 Is Best Value?
ML 320 (M112.942) — reliable V6, the most common engine in the UK parc, and the cheapest six‑cylinder to maintain.
Common Problems
W163 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Engine Page baseline — no Engine Page exists yet for any M111, M112, M113, OM612 or OM628 family. These costs are derived from the EM_Proprietary_Data Table A — Engine Replacement Economics for comparable engines, adjusted for the W163's body‑on‑frame SUV labour access and marked [MB-QUOTE] accordingly. All figures are provisional pending dedicated Engine Pages.
Core Variants
Core Variants
Diesel Variants
Scope note: All variants listed are W163 five‑door SUV only. The W163 was the first‑generation M‑Class and was available exclusively as a five‑door SUV. The successor W164 launched in 2005.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM612.963 (ML 270 CDI)
- 2.2. M112.942 (ML 320)
- 3.3. M112.970 (ML 350)
Most Requested E90 Variants
- 1.1. ML 270 CDI
- 2.2. ML 320
- 3.3. ML 350
Average E90 Replacement Cost
£2,800–£5,000 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. M112 thermostat / valve cover gaskets
- 2.2. OM612 EGR / injector seals
- 3.3. Body‑on‑frame rust / subframe corrosion
Mercedes ML 270 CDI W163 (OM612)
5
enquiries
Mercedes ML 320 W163 (M112)
4
enquiries
Mercedes ML 350 W163 (M112)
3
enquiries
FAQ
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