Mercedes Benz M Class 270 CDI/320 CDI Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz M Class 270 CDI and 320 CDI engine specialists. Compare prices on reconditioned, rebuilt and used engines for the 2.7-litre inline-five and the 3.2-litre inline-six diesels - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £1,800 to £3,000
Used from £1,000 · Reconditioned from £1,800 · Common codes: OM647, OM648
From £1,000
Tested, bare/short engine
From £1,800
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz M Class 270 CDI/320 CDI Replacement Engineto Finding the Best Mercedes Benz M Class 270 CDI/320 CDI Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz M Class 270 CDI/320 CDI - Engine History & Specs at a Glance
The ML 270 CDI launched with the W163 generation in 1999 as Mercedes' first premium SUV diesel, powered by the OM647 2.7-litre inline-five - a robust, turbocharged engine delivering 163hp. In 2002, the ML 320 CDI joined the range with the OM648 3.2-litre straight-six diesel, offering a smoother, more powerful 224hp and representing the pinnacle of W163 diesel refinement before the W164 generation introduced V6 architecture.
Variant HistoryMercedes Benz M Class 270 CDI/320 CDI - Engine History & Specs at a Glance
The ML 270 CDI launched with the W163 generation in 1999 as Mercedes' first premium SUV diesel, powered by the OM647 2.7-litre inline-five - a robust, turbocharged engine delivering 163hp. In 2002, the ML 320 CDI joined the range with the OM648 3.2-litre straight-six diesel, offering a smoother, more powerful 224hp and representing the pinnacle of W163 diesel refinement before the W164 generation introduced V6 architecture.
Mercedes Benz M Class 270 CDI/320 CDI
Fuel TypeDiesel (turbocharged common-rail)
Engine Size Range2.7L-3.2L (OM647: 2,685cc; OM648: 3,222cc)
Power Output Range163-224hp across the variant's historyEngine History Timeline
OM647.961 2.7L inline-five diesel, 163hp @ 4,200rpm (ML 270 CDI, W163 launch)
OM648 3.2L straight-six diesel, 204-224hp @ 4,200rpm (ML 320 CDI, W163)
End of W163 production; OM647 and OM648 replaced by OM642 V6 diesel in W164 generation
Key Specs Snapshot
Fuel TypeDiesel (turbocharged common-rail)Engine Size Range2.7L-3.2L (OM647: 2,685cc; OM648: 3,222cc)Power Output Range163-224hp across the variant's historyYears Produced1999-2005Every engine fitted to the Mercedes Benz M Class 270 CDI and 320 CDI is covered below, with UK rebuilt pricing and known failure points - from OM647 injector seal leaks to OM648 EGR cooler degradation.
Mercedes Benz M Class 270 CDI/320 CDI Engine Codes - Specifications & Replacement CostMercedes Benz M Class 270 CDI/320 CDI Engine Codes - Specifications & Replacement Cost
2.7L Inline-Five Diesel (1999-2005)
Power Output163 hp (120 kW) @ 4,200 rpmTorque400 Nm @ 1,800-2,600 rpmYears Fitted1999-2005Displacement2,685ccCylindersInline 5, 20-valve, DOHC, turbocharged and intercooled
Compatible Trim Levels
- ML 270 CDI
- ML 270 CDI Elegance
- ML 270 CDI Avantgarde
- ML 270 CDI Inspiration
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,000-£1,600
Reconditioned
Addressed known issues, tested
£1,800-£2,200
Rebuilt
Full teardown, upgraded internals
£2,000-£2,600
Common Failure
Injector copper seal leakage - a known issue on OM647 engines, causing diesel fumes in the cabin and a messy engine bay. The seals are inexpensive to replace, but neglect can lead to carbon buildup and more serious issues. Loss of power or limp mode can also occur due to a defective 10A fuse affecting the engine control unit, triggering fault codes such as P1636, P0100, P1403, P1470 or P1189.
The M Class 270 CDI's OM647 inline-five and the 320 CDI's OM648 straight-six are among Mercedes' most durable diesel engines - robust, simple, and capable of 200,000+ miles with proper maintenance. However, both have well-documented weak points that become more pronounced with age and mileage. The OM647 is prone to injector copper seal leaks, while the OM648 can suffer from EGR clogging and oil cooler seal degradation. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing these original failure points, plus a minimum 12-month unlimited-mileage warranty.
The 2.7 CDI's Most Common Annoyance
Affected Vehicles
Mercedes M Class ML 270 CDI (OM647.961, 1999-2005)
Typical Failure Mileage
80,000-150,000 miles
Root Cause
The copper sealing washers under the injectors can fail over time, allowing combustion gases to escape past the injector body. The leaking gases bake into a hard, tar-like carbon crust around the injector - known as "Black Death." This creates diesel fumes in the cabin and a messy engine bay.
Why It Happens
The copper sealing washers under the injectors can fail over time, allowing combustion gases to escape past the injector body. The leaking gases bake into a hard, tar-like carbon crust around the injector - known as "Black Death." This creates diesel fumes in the cabin and a messy engine bay.
Dealer (parts + labour)
£200-£400
Specialist (parts + labour)
£120-£250
What it involves
Replace copper sealing washer, clean injector bore, leak-off test
Suitability
If caught early before injector seizes
1 - 2 daysDealer (parts + labour)
£600-£1,000
Specialist (parts + labour)
£400-£700
What it involves
Replace all five copper sealing washers, clean injector bores, new hold-down bolts
Suitability
If multiple injectors are leaking or preventative maintenance
1 - 2 daysDealer (parts + labour)
£1,500-£2,500
Specialist (parts + labour)
£900-£1,600
What it involves
Specialty pullers, head work, injector seat machining
Suitability
If injector has seized and requires extraction
1 - 2 daysDealer (parts + labour)
£4,500-£6,000
Specialist (parts + labour)
£2,000-£2,600
What it involves
Supply & fit rebuilt OM647 with new injectors, seals, and EGR components, 12-month warranty
Suitability
If injector damage has caused cylinder or head damage
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Minor - Injector seal replacement (one) Minor | £200-£400 | £120-£250 | Replace copper sealing washer, clean injector bore, leak-off test | If caught early before injector seizes | 1 - 2 days |
 Intermediate - Injector seal replacement (all five) Best Value | £600-£1,000 | £400-£700 | Replace all five copper sealing washers, clean injector bores, new hold-down bolts | If multiple injectors are leaking or preventative maintenance | 1 - 2 days |
Major - Injector extraction + head repair Best Value | £1,500-£2,500 | £900-£1,600 | Specialty pullers, head work, injector seat machining | If injector has seized and requires extraction | 1 - 2 days |
Full Replacement - Rebuilt OM647 engine Best Value | £4,500-£6,000 | £2,000-£2,600 | Supply & fit rebuilt OM647 with new injectors, seals, and EGR components, 12-month warranty | If injector damage has caused cylinder or head damage | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 1999-2005 ML 270 CDI or ML 320 CDI is worth approximately £3,000-£8,000 depending on mileage and condition. These classic SUVs sit in a value band where repair decisions require careful consideration - a full engine replacement may approach or exceed the vehicle's value for higher-mileage examples.
Our Recommendation
Our Recommendation
Injector seal leaks on the OM647 are common but usually not urgent. If you notice diesel fumes in the cabin or see carbon buildup around the injectors, have a specialist inspect the seals immediately. Caught early, resealing an injector is a £120-£250 per cylinder job. Caught late, extracting a seized injector can require specialty pullers and head work. On an ML 270 CDI worth £3,000-£8,000, preventative injector seal replacement is always the better investment.
Don't Let Injector Seal Leaks, EGR Clogging, or Electrical Issues Write Off Your Mercedes ML 270 CDI or 320 CDI
Whether you're facing OM647 injector seal leaks on your ML 270 CDI or OM648 EGR clogging on your ML 320 CDI, EnginesMarket makes it simple to compare quotes from trusted UK Mercedes diesel specialists. Every rebuilt engine in our network carries upgraded components addressing the original design weakness - new injector seals, updated EGR components, and bench-tested fuel systems - plus a minimum 12-month unlimited mileage warranty with nationwide delivery and supply & fit options. Don't pay main dealer premiums. Compare prices from independent Mercedes specialists who know these classic inline diesels inside out.
Compare rebuilt OM647 Mercedes M Class 270 CDI engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific Mercedes M Class 270 CDI or 320 CDI. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Mercedes Benz M Class 270 CDI/320 CDI Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes ML 270 CDI or 320 CDI engine replacement cost in the UK-
Short summary: A rebuilt OM647 engine for the ML 270 CDI costs £2,000-£2,600 supply-only; a rebuilt OM648 engine for the ML 320 CDI costs £2,200-£3,000 supply-only. Fitting adds £800-£1,500 depending on complexity - inline diesel engines are relatively accessible.
- ML 270 CDI (OM647.961): rebuilt unit £2,000-£2,600; used engine from £1,000
- ML 320 CDI (OM648): rebuilt unit £2,200-£3,000; used engine from £1,200
- OM647 injector seal replacement (labour only): £120-£250 per cylinder at specialist
- OM648 EGR valve replacement: £250-£500 at specialist
Question 2What are the signs of injector seal failure on a Mercedes ML 270 CDI-
Short summary: Diesel fumes in the cabin and carbon buildup around the injectors are the classic warning signs on the OM647 engine. The copper sealing washers fail over time, allowing combustion gases to escape. If ignored, injectors can seize in the head.
- Diesel smell in the cabin - first warning sign
- Carbon crust ("Black Death") around the injector body
- Tapping or chuffing sound from the injector area
- If caught early, resealing costs £120-£250 per injector
Question 3Is the Mercedes ML 270 CDI or 320 CDI engine reliable-
Short summary: Both the OM647 and OM648 are among Mercedes' most durable diesel engines - the OM647 inline-five and OM648 straight-six are renowned for longevity, with many exceeding 200,000 miles. Regular maintenance and proactive attention to known issues like injector seals and EGR systems are key to their long life.
- OM647 and OM648 are fundamentally robust - 200k+ miles common
- OM647 injector seal leaks are the most frequent issue - £120-£250 per cylinder fix
- OM648 EGR clogging is a maintenance issue, not a fatal flaw
- Regular oil changes with MB 229.51 spec oil extend engine life
Question 4How long do Mercedes ML 270 CDI and 320 CDI engines last-
Short summary: Properly maintained OM647 and OM648 engines routinely reach 200,000+ miles before major work is needed. One owner reported 200,000 miles with only minor issues like injector seals and ancillaries.
- OM647 (270 CDI): 200,000+ miles with regular servicing
- OM648 (320 CDI): 200,000+ miles with proper maintenance
- Injector seal replacement may be needed from 80,000+ miles
- Regular oil changes every 10,000 miles are essential
Question 5Is it worth replacing the engine in my Mercedes ML 270 CDI or 320 CDI-
Short summary: Yes, if the M Class is otherwise in good condition with no rust or major transmission faults. A rebuilt OM647 costs £2,000-£2,600 - comparable to the value of a £3,000-£8,000 vehicle, making it a justifiable investment for well-maintained examples.
- ML 270/320 CDI values: £3,000-£8,000 depending on condition and mileage
- Rebuilt engine with upgraded components fixes original weak points
- Supply & fit typically £2,800-£4,500 depending on engine code
- New engine includes 12-month unlimited mileage warranty
Question 6What oil does my Mercedes ML 270 CDI or 320 CDI need-
Short summary: Mercedes-Benz specifies low-SAPS oil meeting MB 229.51 - typically 5W-30. The OM647 requires approximately 7 litres; the OM648 requires approximately 8 litres.
- OM647 (270 CDI): MB 229.51 5W-30 low-SAPS - protects DPF where fitted
- OM648 (320 CDI): MB 229.51 5W-30 low-SAPS - 8L capacity
- Never use non-approved oil - can cause injector and turbo issues
- Change every 10,000 miles or 12 months
Why Choose UsCompare Mercedes M Class 270 CDI/320 CDIEngine PricesToday
500+ inline diesel engines supplied through our network
12-Month Warranty on every rebuilt ML 270 CDI and 320 CDI engine
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supply & fit available for OM647 and OM648
Comparing quotes for your Mercedes ML 270 CDI or 320 CDI is completely free, with no obligation and no pressure. Enter your registration above to get tailored quotes from UK Mercedes diesel specialists who understand the OM647 inline-five and OM648 straight-six inside out. Whether you need a used engine, a reconditioned unit, or a full rebuilt engine with upgraded injector seals and EGR components, we'll connect you with the right specialist for your exact M Class - with a minimum 12-month warranty on every engine supplied.
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