How much does a Mercedes W251 engine replacement cost in the UK?

A reconditioned W251 engine typically costs £2,500–£14,000 supply only, depending on engine — the volume R 320 CDI diesel sits at £3,000–£5,500. Fitting adds £800–£1,800. Use our calculator for a personalised figure.

What are the common problems with the Mercedes R-Class?

The M272 V6 petrol (R 280/R 350, pre-2011) suffers from balance shaft sprocket wear (60k–100k miles). The OM642 V6 diesel has oil cooler seal leaks and injector seal failure ("Black Death"). The M273 5.5-litre V8 (R 500 late) can suffer timing chain and cam adjuster wear. The Airmatic air suspension system is also a common failure point on higher-mileage examples.

Is the Mercedes R-Class reliable?

It depends heavily on engine choice and maintenance history. The OM642 diesel is the most robust option. The M272 petrols (pre-2011) carry a significant balance shaft risk — check for documented repair. The M113 V8 is solid and proven. The later M273 V8 adds complexity. The R 63 AMG is rare and specialist-only. Always check service history; the R-Class's size means engine bay access is tight, making repairs labour-intensive.

Which Mercedes R-Class engine should I avoid?

The pre-2011 M272 V6 (R 280/R 350) without documented balance shaft replacement is the one to avoid — repair costs can exceed £2,000. The R 63 AMG is a phenomenal car but running costs are astronomical; parts are rare and expensive. The M273 5.5-litre V8 (late R 500) can be costly to maintain if timing chain issues arise.

How do I know if my W251 engine needs replacing?

Cold-start rattle and misfires (M272 balance shaft), oil in the V of the engine and burning oil smell (OM642 diesel), blue smoke or coolant loss (M273 V8), or a sudden loss of power on any engine are the key warnings. Check engine lights, rough idle or misfires also warrant immediate inspection.

Is it worth replacing a Mercedes R-Class engine, or should I scrap the car?

Depends on the car's value. Against a well-kept £9,000 R-Class, a £3,000–£5,500 recon is 33–61% of the car's value — a sensible repair. Against a tired £4,000 example, the same recon is 75–138% — walk away. Our 70% Mercedes threshold is the line.

How long do Mercedes R-Class engines last?

The OM642 V6 diesel can exceed 200,000 miles with proper servicing, oil cooler maintenance and injector seal care. The M272 can reach 150,000+ miles if the balance shaft is addressed. The M113 V8 can exceed 200,000 miles. The M273 V8 can also reach high mileages but requires more frequent maintenance. The R-Class's interior is generally well-built, though the Airmatic suspension may need attention from 80,000 miles.

What is the difference between the W251 and the V251 R-Class?

The W251 is the standard-wheelbase R-Class, while the V251 is the long-wheelbase version offering additional rear legroom and a more spacious third row. Both share the same platform, engines and mechanicals. The V251 is rarer in the UK and was primarily sold in markets like the US and China. Engine costs are identical; body-specific parts differ. This page covers both wheelbases under the W251/V251 designation.

How do I find my Mercedes R-Class engine code?

Listed on the VIN plate (visible through the windscreen, lower passenger side), stamped on the engine block, and detailed in your vehicle registration documents (V5C). Tell us your variant (R 350, R 500, R 63 AMG, etc.) and approximate registration date, and we'll confirm it — 25+ vetted Mercedes specialists will verify it for free.

Mercedes R-Class W251 Engines — The Complete UK Guide

Mercedes R-Class W251 Engine Codes — The Complete Database

Every engine fitted to the W251/V251 chassis — from the frugal V6 diesels to the range-topping AMG V8 that defined this unique Grand Sports Tourer.

Engine CodeFamilyFuelDisplacementPowerYears (W251)Variants (badges)Reliability2025 EnquiriesAvg. Recon Cost

M272.945M272Petrol V63.0L (2996cc)231 bhp (170 kW)2007–2015R 280★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,500–£4,500 [MB-QUOTE]

M272.967M272Petrol V63.5L (3498cc)272 bhp (200 kW)2005–2012R 350★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,800–£5,000 [MB-QUOTE]

M276 (various)M276Petrol V6, turbo3.0–3.5L306–333 bhp2012–2017R 350, R 400★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,500–£6,000 [MB-QUOTE]

M113.960/971M113Petrol V85.0L (4966cc)306 bhp (225 kW)2005–2014R 500★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£4,500–£7,500 [MB-QUOTE]

M273.963M273Petrol V85.5L (5461cc)388 bhp (285 kW)2006–2014R 500 (later)★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£5,000–£8,500 [MB-QUOTE]

M156.980M156Petrol V86.2L (6208cc)510 bhp (375 kW)2006–2010R 63 AMG★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£8,000–£14,000 [MB-QUOTE]

OM642.870OM642Diesel V6, turbo3.0L (2987cc)190 bhp (140 kW)2005–2010R 280 CDI★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

OM642.872OM642Diesel V6, turbo3.0L (2987cc)190 bhp (140 kW)2009–2014R 280 CDI (late)★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

OM642.950OM642Diesel V6, turbo3.0L (2987cc)190–211 bhp (140–155 kW)2005–2014R 280 CDI, R 320 CDI, R 350 CDI★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

Engine CodeFuelPowerYearsReliabilityEnquiriesAvg. Recon Cost

M272.945M272Petrol V6231 bhp (170 kW)2007–2015★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,500–£4,500 [MB-QUOTE]

M272.967M272Petrol V6272 bhp (200 kW)2005–2012★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,800–£5,000 [MB-QUOTE]

M276 (various)M276Petrol V6, turbo306–333 bhp2012–2017★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,500–£6,000 [MB-QUOTE]

M113.960/971M113Petrol V8306 bhp (225 kW)2005–2014★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£4,500–£7,500 [MB-QUOTE]

M273.963M273Petrol V8388 bhp (285 kW)2006–2014★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£5,000–£8,500 [MB-QUOTE]

M156.980M156Petrol V8510 bhp (375 kW)2006–2010★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£8,000–£14,000 [MB-QUOTE]

OM642.870OM642Diesel V6, turbo190 bhp (140 kW)2005–2010★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

OM642.872OM642Diesel V6, turbo190 bhp (140 kW)2009–2014★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

OM642.950OM642Diesel V6, turbo190–211 bhp (140–155 kW)2005–2014★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£3,000–£5,500 [MB-QUOTE]

Overview

Mercedes R-Class W251 — Overview

The Mercedes-Benz R-Class W251 — unveiled at the 2005 New York International Auto Show — was a unique proposition: a mid-size luxury MPV that Mercedes marketed as a "Grand Sports Tourer".

Based on the Vision GST concept from 2002, the R-Class shared its platform with the M-Class (W164) and GL-Class (X164), offering a spacious, six- or seven-seat cabin with the driving dynamics of a luxury sedan. Available in two wheelbases — standard (W251) and long (V251) — the R-Class was assembled in Alabama until 2015, then in Indiana until 2017. A range of V6 and V8 petrol and diesel engines powered the R-Class, with the range-topping R 63 AMG offering 510 bhp from a handbuilt 6.2-litre V8.

Key Facts

Platform

Mercedes W251 (shared with W164 M-Class, X164 GL-Class)

Predecessor

None (new model line)

Successor

None (discontinued 2017)

Sibling body styles in this generation

W251 (short wheelbase), V251 (long wheelbase)

Market Intelligence

No [MB-VERIFIED] enquiry data exists for the R-Class W251 — the model is absent from EM_Proprietary_Data's per-model table, reflecting its low-volume, specialist UK status.

Mercedes R-Class W251 — Overview

The Mercedes-Benz R-Class W251 — unveiled at the 2005 New York International Auto Show — was a unique proposition: a mid-size luxury MPV that Mercedes marketed as a "Grand Sports Tourer".

Based on the Vision GST concept from 2002, the R-Class shared its platform with the M-Class (W164) and GL-Class (X164), offering a spacious, six- or seven-seat cabin with the driving dynamics of a luxury sedan. Available in two wheelbases — standard (W251) and long (V251) — the R-Class was assembled in Alabama until 2015, then in Indiana until 2017. A range of V6 and V8 petrol and diesel engines powered the R-Class, with the range-topping R 63 AMG offering 510 bhp from a handbuilt 6.2-litre V8.

Key Facts

Platform

Mercedes W251 (shared with W164 M-Class, X164 GL-Class)

Predecessor

None (new model line)

Successor

None (discontinued 2017)

Sibling body styles in this generation

W251 (short wheelbase), V251 (long wheelbase)

Market Intelligence

No [MB-VERIFIED] enquiry data exists for the R-Class W251 — the model is absent from EM_Proprietary_Data's per-model table, reflecting its low-volume, specialist UK status.

Best & Worst Engines

Thin-Data Summary

“The R-Class engine range is defined by variety — and some notable pitfalls. For most buyers, the OM642 V6 diesel (R 280/320/350 CDI) is the standout: smooth, refined and robust with few major failure modes beyond the well-documented oil cooler seal leak and injector seal issues. The M272 V6 petrol (R 280/R 350) is a solid choice, but early examples suffer from the infamous balance shaft sprocket wear — a costly repair that can exceed £2,000. The later M276 V6 is a significant improvement, addressing many of the M272's weaknesses. The M113/M273 V8s (R 500) deliver effortless V8 grunt, with the M273's 5.5-litre unit offering 388 bhp — but running costs are high and the M273 can suffer from timing chain and cam adjuster issues. The R 63 AMG (M156 V8) is a genuine rarity: 510 bhp from a handbuilt 6.2-litre V8, but it was produced for just one model year and is both rare and expensive to maintain. Buying instruction: for long-term ownership, the OM642 diesel is the most reliable choice; for petrol buyers, prioritise post-2012 M276-engined cars and avoid early M272 examples without documented balance shaft work.”

Who it's for:

Thin-Data Summary

“The R-Class engine range is defined by variety — and some notable pitfalls. For most buyers, the OM642 V6 diesel (R 280/320/350 CDI) is the standout: smooth, refined and robust with few major failure modes beyond the well-documented oil cooler seal leak and injector seal issues. The M272 V6 petrol (R 280/R 350) is a solid choice, but early examples suffer from the infamous balance shaft sprocket wear — a costly repair that can exceed £2,000. The later M276 V6 is a significant improvement, addressing many of the M272's weaknesses. The M113/M273 V8s (R 500) deliver effortless V8 grunt, with the M273's 5.5-litre unit offering 388 bhp — but running costs are high and the M273 can suffer from timing chain and cam adjuster issues. The R 63 AMG (M156 V8) is a genuine rarity: 510 bhp from a handbuilt 6.2-litre V8, but it was produced for just one model year and is both rare and expensive to maintain. Buying instruction: for long-term ownership, the OM642 diesel is the most reliable choice; for petrol buyers, prioritise post-2012 M276-engined cars and avoid early M272 examples without documented balance shaft work.”

Who it's for:

Mercedes R-Class W251 — Ownership Economics

EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership Verdict

M272.945 (R 280)60k–100kBalance shaft sprocket£1,500–£3,000£2,500–£4,500

Watch — pre-2011 balance shaft risk

M272.967 (R 350)60k–100kBalance shaft sprocket£1,500–£3,000£2,800–£5,000

Watch — same as R 280

M276 (R 350/400)80k–150kTiming chain (less common)£800–£2,000£3,500–£6,000

Best petrol — improved over M272

M113.960/971 (R 500)80k–150k+Generally reliable—£4,500–£7,500

Solid V8 — robust and proven

M273.963 (R 500 late)60k–100kTiming chain, cam adjusters£1,500–£3,000£5,000–£8,500

Watch — complex V8, higher costs

M156.980 (R 63 AMG)40k–70kValve train wear, oil consumption£2,000–£4,000£8,000–£14,000

Rare icon — AMG tax applies

OM642.870/872/950 (CDI)100k–180kOil cooler seal, injector seals£800–£1,500£3,000–£5,500

Best diesel — smooth, refined, reliable

EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership Verdict

M272.945 (R 280)60k–100kBalance shaft sprocket£1,500–£3,000£2,500–£4,500

Watch — pre-2011 balance shaft risk

M272.967 (R 350)60k–100kBalance shaft sprocket£1,500–£3,000£2,800–£5,000

Watch — same as R 280

M276 (R 350/400)80k–150kTiming chain (less common)£800–£2,000£3,500–£6,000

Best petrol — improved over M272

M113.960/971 (R 500)80k–150k+Generally reliable—£4,500–£7,500

Solid V8 — robust and proven

M273.963 (R 500 late)60k–100kTiming chain, cam adjusters£1,500–£3,000£5,000–£8,500

Watch — complex V8, higher costs

M156.980 (R 63 AMG)40k–70kValve train wear, oil consumption£2,000–£4,000£8,000–£14,000

Rare icon — AMG tax applies

OM642.870/872/950 (CDI)100k–180kOil cooler seal, injector seals£800–£1,500£3,000–£5,500

Best diesel — smooth, refined, reliable

The W251 rule

A £3,000–£5,500 OM642 recon against a £4,000–£12,000 R-Class sits at 25–138% of the car's value. On a sub-£5,000 example, that brushes our 70% Mercedes threshold — we'll honestly tell you to walk away. Against a well-kept £9,000+ example, the same recon drops to a more manageable 33–61% — a repair decision, not a financial one. Value the car first.

Key Takeaways

Which W251 Costs Least To Own?
R 280 CDI (OM642) — simple V6 diesel, robust, well-supported.
Which W251 Costs Most To Own?
R 63 AMG (M156) — handbuilt V8 complexity, AMG-specific parts, rarity.
Which W251 Is Best Value?
R 320/350 CDI (OM642) — the most reliable engine in the range with strong economy and refinement.

Common Problems

01

M272

Balance Shaft Sprocket Wear

Affected models:

W251 R 280, R 350 (M272.945/967), 2005–2011.

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The M272 V6 petrol engine suffers from premature wear to the balance shaft sprocket, which is made of softer metal than the chain. This causes the timing chain to jump, leading to engine misfire, rough running and, in severe cases, piston-to-valve contact.

Tiered Cost Table

Our Recommendation

If you're buying a pre-2011 M272-engined R-Class, check the engine number against the affected range — Mercedes revised the sprocket in 2011. A £1,200–£2,000 preventative repair is cheaper than the £2,800–£5,000 replacement that follows if ignored.

Compare M272 engine prices for your W251

02

OM642

Oil Cooler Seal Leak

Affected models:

W251 R 280/320/350 CDI (OM642.870/872/950), 2005–2014.

Typical failure mileage:

80,000–150,000 miles.

Root cause:

The oil cooler seals on the OM642 V6 diesel are a known weak point across the Mercedes range. The seals degrade over time, allowing oil to leak into the valley of the V6. The repair is labour-intensive, requiring removal of the intake manifold and significant disassembly.

Tiered Cost Table

Our Recommendation

On any OM642-engined R-Class over 80,000 miles, budget for an oil cooler seal replacement — £800–£1,500 is a reasonable preventative cost to avoid potential engine damage from oil loss.

Compare OM642 engine prices for your W251

03

OM642

Injector Seal Failure ("Black Death")

Affected models:

W251 R 280/320/350 CDI (OM642.870/872/950), 2005–2014.

OM642 Injector Seal Failure ("Black Death")

Typical failure mileage:

80,000–130,000 miles.

Root cause:

The injector seals on the OM642 diesel engine degrade over time, allowing combustion gases to escape past the seal. This causes a characteristic black, tar-like carbon buildup around the injector — known in Mercedes circles as "Black Death" — which can eventually seize the injector in the cylinder head.

Tiered Cost Table

Our Recommendation

At the first sign of a diesel smell in the cabin or visible black residue around injectors, get the seals inspected immediately — a £400–£800 seal replacement is far cheaper than the £900–£1,500 head repair that follows if ignored.

Compare OM642 engine prices for your W251

04

Airmatic

Air Suspension Failures

Affected models:

All W251 variants with Airmatic air suspension (common on UK models).

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The Airmatic air suspension system uses air struts and a compressor that can fail over time. The struts develop leaks, the compressor overheats and fails, or the valve block malfunctions. This is one of the most common and expensive non-engine issues on the R-Class.

Tiered Cost Table

Our Recommendation

On any R-Class over 60,000 miles, have the Airmatic system inspected — a £300–£600 preventative repair is cheaper than the £1,200–£2,500 replacement that follows if ignored.

Compare W251 air suspension repair quotes

W251 Engine Replacement Costs — By Engine and Condition

VariantEngine CodeUsed (Supply)Reconditioned (Supply)Rebuilt (Supply)Labour Hours

R 280M272.945£1,200–£2,500£2,500–£4,500£3,500–£6,00012–14 hrs

R 350M272.967£1,500–£2,800£2,800–£5,000£4,000–£6,50012–14 hrs

R 350/400 (post-2012)M276£1,800–£3,200£3,500–£6,000£5,000–£8,00012–14 hrs

R 500 (5.0L)M113.960/971£2,000–£3,800£4,500–£7,500£6,500–£10,00014–18 hrs

R 500 (5.5L)M273.963£2,500–£4,500£5,000–£8,500£7,500–£12,00014–18 hrs

R 63 AMGM156.980£4,000–£7,000£8,000–£14,000£12,000–£18,00018–24 hrs

R 280/320/350 CDIOM642.870/872/950£1,500–£2,800£3,000–£5,500£4,500–£7,50012–14 hrs

Core Variants

Diesel Variants

R 280 CDIR 320 CDIR 350 CDI

Petrol Variants

R 280R 350R 350 CGIR 400R 500R 63 AMG

Scope note: All variants listed are W251/V251 (R-Class, 2005–2017) only. The R 63 AMG was produced for the 2007 model year only, featuring a handbuilt 6.2-litre M156 V8. The R 500 was offered with both the M113 5.0-litre V8 (306 bhp) and the later M273 5.5-litre V8 (388 bhp). The R 400 (M276) replaced the R 350 in some markets post-2012.

Core Variants

Diesel Variants

R 280 CDIR 320 CDIR 350 CDI

Petrol Variants

R 280R 350R 350 CGIR 400R 500R 63 AMG

Scope note: All variants listed are W251/V251 (R-Class, 2005–2017) only. The R 63 AMG was produced for the 2007 model year only, featuring a handbuilt 6.2-litre M156 V8. The R 500 was offered with both the M113 5.0-litre V8 (306 bhp) and the later M273 5.5-litre V8 (388 bhp). The R 400 (M276) replaced the R 350 in some markets post-2012.

Market Intelligence

Most Requested E90 Engines (2025)

Most Requested E90 Variants

Average E90 Replacement Cost

Most Common E90 Failures

FAQ

BMW 3 Series E90 rear three-quarter view

Why UK Mercedes R-Class W251 Owners Trust MercedesEngines.uk

Trusted W251 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real R-Class owners, as part of the Engine Finders network.
Compare W251 Engine Replacement Companies
see prices, warranty terms and supply-and-fit options side-by-side before you commit to any repair.
UK Engine Replacement Services for W251
covering every variant from the R 280 CDI to the R 63 AMG, with supply-only or full supply-and-fit available nationwide.

Find the best Mercedes R-Class W251 engine replacement UK drivers rely on. Compare real prices from trusted Mercedes specialists on EnginesMarket today and get back on the road with confidence.

Compare Mercedes R-Class W251 Engine Prices on EnginesMarket

Why UK Mercedes R-Class W251 Owners Trust MercedesEngines.uk

Trusted W251 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real R-Class owners, as part of the Engine Finders network.
Compare W251 Engine Replacement Companies
see prices, warranty terms and supply-and-fit options side-by-side before you commit to any repair.
UK Engine Replacement Services for W251
covering every variant from the R 280 CDI to the R 63 AMG, with supply-only or full supply-and-fit available nationwide.

Find the best Mercedes R-Class W251 engine replacement UK drivers rely on. Compare real prices from trusted Mercedes specialists on EnginesMarket today and get back on the road with confidence.

Compare Mercedes R-Class W251 Engine Prices on EnginesMarket