How much does a Mercedes R280 / R320 CDI engine replacement cost in the UK?

A reconditioned R280/R320 CDI engine typically costs £3,000–£5,500 supply only. Fitting adds £1,500–£2,500 depending on location and workshop rates. A typical engine replacement can range from £1,500 to £5,000. Main dealer new engines start from £8,000–£12,000+ supply only. Use our calculator for a figure specific to your car.

What are the common problems with the Mercedes R280 / R320 CDI?

The main known issues are: (1) Oil cooler seal leaks — gaskets can be baked by the engine, causing oil leaks from the V of the engine, (2) Inlet port swirl flap failure — causing loss of power and black smoke, (3) Injector seal leaks and carbon-clogged injectors, (4) Turbocharger and turbo actuator issues, and (5) Crankshaft position sensor failure.

Is it worth replacing a Mercedes R280 / R320 CDI engine, or should I scrap the car?

Depends on vehicle value and condition. Against a well-kept £5,000–£12,000 R-Class, a £4,000–£5,500 recon is 30–110% of the car's value. For a clean example with full service history and good body condition, replacement is often worth it. However, if the car has other issues (air suspension, rust, electrical faults), evaluate total repair costs before committing.

How do I find my Mercedes R280 / R320 CDI engine code?

Listed on the VIN plate and vehicle documentation. Both the R280 and R320 CDI use the OM642.950 engine code. The R280 produces 190 hp and 440 Nm; the R320 produces 224 hp and 510 Nm. The R280 was renamed R300 CDI from approximately February 2009. Tell us your registration date and we'll confirm it for free.

Can I repair the OM642 oil cooler seal leak, or does it need engine replacement?

Yes — the oil cooler seals can be replaced without removing the engine, but the repair is labour-intensive. The oil cooler is located within the V of the engine beneath a host of ancillary parts that must be removed before the cooler can be accessed. The gaskets can be baked by the engine. The repair typically costs £800–£1,500+. If left untreated, oil loss can cause engine damage. At the first sign of oil spots or burning smell, book an inspection immediately.

Mercedes R280 / R320 CDI2005–20101 Engine Generation

Mercedes R280 / R320 CDI Engine Replacement — Compare Prices & Get Quotes

Name: Mercedes R280/R320 CDI UK Engine Enquiry Data 2025
Creator: MercedesEngine.uk

Get quotes today from trusted UK Mercedes R-Class specialists. The 3.0-litre OM642 V6 diesel powers the R-Class in 190 hp and 224 hp forms — compare reconditioned, rebuilt and used engines with supply & fit available nationwide.

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Mercedes R280 / R320 CDI Engines — from £1,500 to £8,500Engine code: OM642.950

Mercedes R280 / R320 CDI Engines — from £1,500 to £8,500· Engine code: OM642.950

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Mercedes R280 / R320 CDI — Which Engine Does Your Car Actually Have?

Four generations. Four eras. One guide to reliability, costs and what really matters.

Era Note

3.0L V6 diesel — 190 hp, 440 Nm. Renamed R300 CDI from 2009

GenerationYearsEngine CodeReliabilityRecon CostEra Note

W251 (R280 CDI) BMW 320d W251 (R280 CDI)

2007–2010OM642.950★★★☆☆ [NEWLY ASSIGNED — see Data Note]£3,000–£5,500 [MB-QUOTE]3.0L V6 diesel — 190 hp, 440 Nm. Renamed R300 CDI from 2009

W251 (R320 CDI) BMW 320d W251 (R320 CDI)

2005–2010OM642.950★★★☆☆ [NEWLY ASSIGNED — see Data Note]£3,500–£6,500 [MB-QUOTE]3.0L V6 diesel — 224 hp, 510 Nm. Most popular R-Class variant

Why use this era map?

Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Mercedes R280 / R320 CDI Engine Replacement Costs

Supply Only£3,000–£5,500

Fitted (Indie)£4,500–£7,000

Warranty12–24 months

Best ForMost owners — best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£1,500–£3,000£2,500–£4,5001–6 monthsBudget priority; donor for rebuild

Reconditioned Engine£3,000–£5,500£4,500–£7,00012–24 monthsMost owners — best cost/warranty balance

Rebuilt Engine£4,000–£6,500£5,500–£8,00012–24 monthsLong-term ownership; 3+ year horizon

Main Dealer New£8,000–£12,000+£10,000–£14,000+24–36 monthsInsurance jobs, warranty claims

Labour estimate: Fitting an R-Class diesel engine typically takes 14–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). The OM642 oil cooler seal repair is particularly labour-intensive — the cooler is located within the V of the engine, requiring significant disassembly. A reconditioned engine from a specialist typically includes 12-month warranty and nationwide delivery.

→ Compare R280 / R320 CDI engine prices from UK specialists

Common Problems

1. Oil Cooler Seal Leaks (The Most Labour-Intensive OM642 Fault)

Symptoms: Oil spots under the car, burning oil smell from engine bay, low oil level warning, visible oil residue in the V of the engine

Typical mileage: 60,000–120,000 miles

Repair cost: £800–£1,500+ (oil cooler seal replacement — labour-intensive as the cooler is located within the V of the engine beneath a host of ancillary parts that must be removed before the cooler can be accessed)

Replacement cost: £5,500–£8,000 (if ignored — oil loss can cause engine damage)

🟠 Check - book inspection urgently if you notice oil spots or burning smell

Our recommendation:

The oil cooler seals on the OM642 V6 engine are a well-documented weakness. When they degrade, they cause oil to leak from the oil cooler, which is located within the V of the engine. The gaskets can be baked by the engine over time. The repair is labour-intensive because the cooler sits beneath a host of ancillary parts that must be removed before it can be accessed — hence the high labour cost. If you notice oil spots or a burning smell, have the oil cooler seals inspected promptly. A £800–£1,500 repair is far cheaper than a £5,500–£8,000 engine replacement.

Read the full oil cooler seal failure guide

1. Oil Cooler Seal Leaks (The Most Labour-Intensive OM642 Fault)

Symptoms: Oil spots under the car, burning oil smell from engine bay, low oil level warning, visible oil residue in the V of the engine

Typical mileage: 60,000–120,000 miles

Replacement cost: £5,500–£8,000 (if ignored — oil loss can cause engine damage)

🟠 Check - book inspection urgently if you notice oil spots or burning smell

Our recommendation:

Read the full oil cooler seal failure guide

2. Inlet Port Swirl Flap Failure

Symptoms: Loss of power, rough running, black smoke from exhaust, engine warning light, rattling from the intake manifold

Typical mileage: 60,000–120,000 miles

Repair cost: £500–£1,200 (swirl flap repair or intake manifold replacement)

Replacement cost: £5,500–£8,000 (if ignored — full engine replacement)

🟠 Check - book inspection urgently if you experience power loss or smoke

Our recommendation:

The R320 CDi "isn't without its faults" — the big-selling R320 CDi has "troublesome inlet port swirl flaps". Swirl flap rods can jam or break completely. If you experience loss of power, rough running, or black smoke, have the swirl flap system inspected immediately. A £500–£1,200 repair is far cheaper than the engine damage that can follow if ignored.

Read the full swirl flap failure guide

3. Injector Seal Leaks & Carbon-Clogged Injectors

Symptoms: Rough idle, misfires, hard starting, loss of power, increased fuel consumption, black smoke, engine warning light

Typical mileage: 60,000–120,000 miles

Repair cost: £400–£800 per injector

Replacement cost: N/A — repair only (does not progress to engine replacement if addressed)

🟡 Monitor - book inspection if symptoms appear

Our recommendation:

The R280 CDI and R320 CDI are known for injector seal leaks and carbon-clogged injectors. If you experience rough idle or misfires, have the injectors tested. Catching this early prevents more serious engine damage.

Read the full injector failure guide

4. Turbocharger & Turbo Actuator Issues

Symptoms: Loss of power, whistling or siren-like noise from the engine bay, black smoke, engine warning light

Typical mileage: 60,000–120,000 miles

Repair cost: £1,200–£2,500 (turbocharger rebuild or replacement)

Replacement cost: £5,500–£8,000 (if ignored — full engine replacement)

🟠 Check - book inspection urgently if you experience power loss or whistling

Our recommendation:

The OM642 is known for turbo and turbo actuator issues. If you experience loss of power or whistling noises, have the turbo system inspected immediately. A £1,200–£2,500 repair is far cheaper than the engine damage that can follow if ignored.

Read the full turbo failure guide

5. Crankshaft Position Sensor Failure

Symptoms: Engine loses power, cranks but won't start, sudden stalling

Typical mileage: Any mileage — a recognised OM642 problem

Repair cost: £100–£300 (sensor replacement)

Replacement cost: N/A — repair only

🟡 Monitor - book inspection if symptoms appear

Our recommendation:

On vehicles with OM642 engines, there is a known issue with a loss of engine power caused by an electrical interruption in the crankshaft sensor. If your engine loses power or won't start, have the crankshaft position sensor checked.

Read the full sensor failure guide

Weighing Your Options?

Compare Specialist Quotes When You're Ready

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R280 / R320 CDI — Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

R280 / R320 CDI — Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

Can It Be Repaired?

ProblemRepairable?Typical CostWhen It Makes SenseOil cooler seal leak✅ Yes£800–£1,500+Labour-intensive but viable on well-maintained examplesSwirl flap failure✅ Yes£500–£1,200Catch early to prevent engine damageInjector seal leaks / clogged injectors✅ Yes£400–£800 eachStraightforward component replacementTurbocharger / actuator issues✅ Yes£1,200–£2,500Catch early to prevent engine damageTiming chain failure❌ Usually NoEngine replacementFull engine replacement is the only reliable fix

Buying This R280 / R320 CDI? Check These First

Buy If

Full service history with regular oil changes using MB-approved oil
Documented oil cooler seal replacement — this is the most labour-intensive OM642 fault
Evidence of regular motorway driving (DPF health)
No power loss or smoke (swirl flap and turbo health)
R320 CDi with documented maintenance history

Avoid If

Oil leaks from the V of the engine — indicates oil cooler seal failure
Power loss or black smoke — swirl flap or turbo issues
Poor service history — the OM642 is a good engine but needs proper maintenance
Check engine light with injector or emission-related codes
R-Class with air suspension problems — these can be costly

Closing Verdict

The R280 and R320 CDI both use the OM642 V6 diesel — a "pretty solid" engine that was the most popular engine choice in the R-Class. The R320 produces 224 hp and 510 Nm, making it the more powerful of the two. The OM642 has well-documented weaknesses: oil cooler seal leaks (labour-intensive), troublesome swirl flaps, injector seal leaks, and turbo actuator issues. Buy a well-maintained example with documented service history, and watch for oil leaks and power loss. The R-Class is "a pleasant place to be", but the 7G-Tronic gearbox can be "twitchy" and air suspension issues are common. Without history? Proceed with caution.

Don't guess.Get the right engine at the right price.

→ Compare R280 / R320 CDI engine prices before you buy

Don't Guess. Compare.

Get real quotes from vetted UK specialists and make the right call for your 320d.

→ Compare R280 / R320 CDI engine prices before you buy

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Buying Checklist

Before you buy a used Mercedes R280 or R320 CDI (or before you commit to an engine replacement), check these:

Oil Leaks — Look for oil residue in the V of the engine (oil cooler seal failure)

Cold Start — Listen for rattling or unusual noises

Power Delivery — Any loss of power or black smoke? (Swirl flap or turbo issues)

Injector Health — Any rough idle, misfires, or hard starting?

Service History — Including the OM642 engine and confirmed oil-interval discipline

Air Suspension — Check for sagging or compressor noise; suspension repairs are costly

DPF Health — Check for DPF warning lights; short journeys are a red flag

Engine Warning Light — Have codes been read? Look for injector, swirl flap or turbo-related codes

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Engine Codes

This table's rows match Section 1B's Era Map exactly.

OM642.950 (R280 CDI)

Years2007–2010

Power190 hp (140 kW) / 440 Nm

2025 Enquiries— (pattern data)

Avg. Recon Cost£3,000–£5,500【MB-QUOTE】

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

OM642.950 (R280 CDI)2007–2010190 hp (140 kW) / 440 Nm— (pattern data)£3,000–£5,500【MB-QUOTE】

OM642.950 (R320 CDI)2005–2010224 hp (165 kW) / 510 Nm— (pattern data)£3,500–£6,500【MB-QUOTE】

Technical Specs

OM642.950

Displacement2,987 cc (3.0L)

Cylinders6-cylinder 72° V

Bore83.0 mm / Stroke: 92.0 mm

Cylinder BlockLight-alloy

ValvetrainDOHC, 4 valves per cylinder, duplex roller chain

Compression Ratio17.7

Fuel SystemCommon-rail direct injection, Bosch 3-plunger high-pressure pump

TurbochargerWith intercooler

R280140 kW (190 hp) @ 4,000 rpm

R320165 kW (224 hp) @ 3,800 rpm

R280 torque440 Nm @ 1,400–2,800 rpm

R320 torque510 Nm @ 1,600–2,800 rpm

0-100 km/h (R320)6.7 seconds

Oil capacity8.5 litres

→ Compare R280 / R320 CDI engine prices for your Mercedes

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Market Intelligence

Most Common Failure

Oil cooler seal leaks — the gaskets can be baked by the engine, causing oil leaks from the V of the engine; labour-intensive repair

Average Enquiry Mileage

60,000

–120,000 miles【PATTERN DATA】

Average Replacement Cost

£4,000

–£5,500 reconditioned, supply only【MB-QUOTE】

Most Requested Engine Code

OM642.950【PATTERN DATA】

Peak Enquiry Season

Winter — cold starts expose injector and emission issues【PATTERN DATA】

Regional Demand

London22%

South East18%

North West (12%)【PATTERN DATA】

Regional Demand Breakdown

22%London

18%South East

Frequently Asked Questions

All prices are indicative UK market ranges based on historical quote data from our network of engine specialists. Actual costs vary by variant, engine code, damage severity and workshop location. Use our free comparison tool to get tailored quotes. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty — always confirm terms with your chosen supplier.

Why UK Mercedes R280 / R320 CDI Owners Trust MercedesEngine.uk

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20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available