Mercedes Benz M Class 250 BlueTEC/350 BlueTEC Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz M Class 250 BlueTEC and 350 BlueTEC engine specialists. Compare prices on reconditioned, rebuilt and used engines for the advanced Euro 6 compliant BlueTEC diesels - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £2,400 to £4,800
Used from £1,200 · Reconditioned from £2,400 · Common codes: OM651.960, OM642.826, OM642.820
From £1,200
Tested, bare/short engine
From £2,400
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 250 BlueTEC/350 BlueTEC Replacement Engineto Finding the Best Mercedes Benz M Class 250 BlueTEC/350 BlueTEC Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz M Class 250 BlueTEC/350 BlueTEC - Engine History & Specs at a Glance
The ML 250 BlueTEC and ML 350 BlueTEC launched with the W166 generation in 2011, representing Mercedes' most advanced diesel technology at the time. The ML 250 BlueTEC introduced the OM651 2.1-litre four-cylinder diesel - a high-efficiency engine already proven in the S-Class - while the ML 350 BlueTEC continued with the refined OM642 3.0-litre V6 diesel. Both variants featured BlueTEC emissions technology with AdBlue SCR systems for Euro 6 compliance, making them some of the cleanest diesel SUVs of their era.
Variant HistoryMercedes Benz M Class 250 BlueTEC/350 BlueTEC - Engine History & Specs at a Glance
The ML 250 BlueTEC and ML 350 BlueTEC launched with the W166 generation in 2011, representing Mercedes' most advanced diesel technology at the time. The ML 250 BlueTEC introduced the OM651 2.1-litre four-cylinder diesel - a high-efficiency engine already proven in the S-Class - while the ML 350 BlueTEC continued with the refined OM642 3.0-litre V6 diesel. Both variants featured BlueTEC emissions technology with AdBlue SCR systems for Euro 6 compliance, making them some of the cleanest diesel SUVs of their era.
Mercedes Benz M Class 250 BlueTEC/350 BlueTEC
Fuel TypeDiesel (BlueTEC with AdBlue SCR emissions system)
Engine Size Range2.1L-3.0L (OM651: 2,143cc; OM642: 2,987cc)
Power Output Range204-258hp across the variant's historyEngine History Timeline
OM651.960 2.1L four-cylinder BlueTEC diesel, 204hp (ML 250 BlueTEC, W166 launch)
OM642.826 3.0L V6 BlueTEC diesel, 258hp (ML 350 BlueTEC, W166 launch)
2015 - Both variants continue with 9G-TRONIC transmission introduced on facelift models
M-Class rebranded to GLE; BlueTEC variants continue under GLE nameplate
Key Specs Snapshot
Fuel TypeDiesel (BlueTEC with AdBlue SCR emissions system)Engine Size Range2.1L-3.0L (OM651: 2,143cc; OM642: 2,987cc)Power Output Range204-258hp across the variant's historyYears Produced2011-2015Every engine fitted to the Mercedes Benz M Class 250 BlueTEC and 350 BlueTEC is covered below, with UK rebuilt pricing and known failure points - from OM651 timing chain gasket leaks to OM642 oil cooler seal degradation and AdBlue system issues.
Mercedes Benz M Class 250 BlueTEC/350 BlueTEC Engine Codes - Specifications & Replacement CostMercedes Benz M Class 250 BlueTEC/350 BlueTEC Engine Codes - Specifications & Replacement Cost
2.1L Four-Cylinder BlueTEC Diesel (2011-2015)
Power Output204 hp (150 kW) @ 3,800 rpmTorque500 Nm @ 1,600-1,800 rpmYears Fitted2011-2015Displacement2,143ccCylindersInline 4, DOHC, 16-valve, twin-turbochargedEngine CodeOM 651 DE 22 LA SCR
Compatible Trim Levels
- ML 250 BlueTEC 4MATIC
- ML 250 BlueTEC AMG Line
- ML 250 BlueTEC Sport
Mercedes Benz M Class 250 BlueTEC/350 BlueTEC engine replacement
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,200-£2,000
Reconditioned
Addressed known issues, tested
£2,200-£3,000
Rebuilt
Full teardown, upgraded internals
£2,500-£3,500
Common Failure
Timing chain tensioner gasket oil leaks - a known recall issue affecting 2015 ML 250 BlueTEC models. Oil may leak from around the chain tensioner gasket area, increasing fire risk. Water accumulation in the spare tyre wheel well can also damage the fuel pump control unit, causing engine stalls.
The M Class 250 BlueTEC's OM651 four-cylinder and the 350 BlueTEC's OM642 V6 are advanced Euro 6 diesel engines, but both have well-documented issues that drive replacement enquiries. The OM651 suffers from timing chain tensioner gasket oil leaks and fuel pump control unit failures, while the OM642 V6 is prone to oil cooler seal degradation and AdBlue system faults. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing these original failure points, plus a minimum 12-month unlimited-mileage warranty.
The 250 BlueTEC's Recall Issue
Affected Vehicles
Mercedes M Class ML 250 BlueTEC (OM651.960, 2011-2015)
Typical Failure Mileage
40,000-80,000 miles
Root Cause
Oil may leak from around the chain tensioner gasket area due to variations in material tolerances during a certain production period. Mercedes issued a recall for 2015 ML 250 BlueTEC models over this issue. Leaking oil may drip onto a hot engine surface, increasing the risk of a fire.
Why It Happens
Oil may leak from around the chain tensioner gasket area due to variations in material tolerances during a certain production period. Mercedes issued a recall for 2015 ML 250 BlueTEC models over this issue. Leaking oil may drip onto a hot engine surface, increasing the risk of a fire.
Dealer (parts + labour)
£0 (if recall applies)
Specialist (parts + labour)
N/A
What it involves
Replace chain tensioner sealing ring per recall procedure
Suitability
Check your VIN for outstanding recall status
1 - 2 daysDealer (parts + labour)
£600-£1,000
Specialist (parts + labour)
£400-£700
What it involves
Replace timing chain tensioner, sealing ring, inspect chain guides
Suitability
If recall not performed or symptoms persist
1 - 2 daysDealer (parts + labour)
£5,000-£7,000
Specialist (parts + labour)
£2,500-£3,500
What it involves
Supply & fit rebuilt OM651 with updated tensioner components, 12-month warranty
Suitability
If oil leak has caused engine 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 |
|---|---|---|---|---|---|
 Recall Remedy - Chain tensioner sealing ring replacement Minor | £0 (if recall applies) | N/A | Replace chain tensioner sealing ring per recall procedure | Check your VIN for outstanding recall status | 1 - 2 days |
 Intermediate - Timing chain tensioner replacement Best Value | £600-£1,000 | £400-£700 | Replace timing chain tensioner, sealing ring, inspect chain guides | If recall not performed or symptoms persist | 1 - 2 days |
Full Replacement - Rebuilt OM651 engine Best Value | £5,000-£7,000 | £2,500-£3,500 | Supply & fit rebuilt OM651 with updated tensioner components, 12-month warranty | If oil leak has caused engine damage | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 2011-2015 ML 250 BlueTEC 4MATIC is worth approximately £8,000-£16,000 depending on mileage and condition. The ML 250 BlueTEC sits in the £8,000-£15,000 band - replacement cost is typically justified for well-maintained examples.
Our Recommendation
Our Recommendation
If your ML 250 BlueTEC is subject to the chain tensioner gasket recall, have the work performed at a Mercedes dealer free of charge. If symptoms persist or the recall doesn't apply, specialist tensioner replacement at £400-£700 is significantly cheaper than dealer rates. On an ML 250 BlueTEC worth £8,000-£16,000, preventative attention to this issue is always the better investment.
Don't Let Timing Chain Gasket Leaks, AdBlue System Faults, or Stalling Issues Write Off Your Mercedes ML 250 or 350 BlueTEC
Whether you're facing OM651 timing chain gasket oil leaks on your ML 250 BlueTEC, OM642 AdBlue system issues on your ML 350 BlueTEC, or intermittent stalling on either variant, 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 - updated tensioner components, reinforced oil cooler seals, and new emission system parts - 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 BlueTEC engines inside out.
Compare rebuilt OM651 Mercedes M Class 250 BlueTEC 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 250 BlueTEC or 350 BlueTEC. 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 250 BlueTEC/350 BlueTEC Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes ML 250 BlueTEC or 350 BlueTEC engine replacement cost in the UK-
Short summary: A rebuilt OM651 engine for the ML 250 BlueTEC costs £2,500-£3,500 supply-only; a rebuilt OM642 engine for the ML 350 BlueTEC costs £3,500-£4,800 supply-only. Fitting adds £800-£1,500 depending on complexity - BlueTEC emissions systems require specialist knowledge.
- ML 250 BlueTEC (OM651.960): rebuilt unit £2,500-£3,500; used engine from £1,200
- ML 350 BlueTEC (OM642.826): rebuilt unit £3,500-£4,800; used engine from £1,800
- OM651 timing chain tensioner replacement: £400-£700 at specialist
- OM642 oil cooler seal replacement: £900-£1,400 at specialist
Question 2What are the signs of timing chain gasket failure on a Mercedes ML 250 BlueTEC-
Short summary: Oil leaks from around the chain tensioner gasket area are the classic warning sign on the OM651 engine. Mercedes issued a recall for 2015 ML 250 BlueTEC models over this issue. Leaking oil may drip onto a hot engine surface, increasing fire risk.
- Oil leak from chain tensioner gasket area
- Oil dripping onto hot engine surfaces - fire risk
- Check your VIN for outstanding recall status
- If recall doesn't apply, specialist repair costs £400-£700
Question 3Is the Mercedes ML 350 BlueTEC V6 engine (OM642) reliable-
Short summary: The OM642 V6 is a fundamentally strong engine, but BlueTEC variants face emissions system challenges. DPF, AdBlue, and EGR system issues are common, with owners reporting persistent check engine lights. Oil cooler seal degradation is also a known weakness.
- OM642 V6 is fundamentally robust with good longevity
- AdBlue/SCR system faults are the most common issue
- Oil cooler seal degradation affects many units
- Well-maintained OM642 BlueTEC engines exceed 150,000 miles
Question 4How long do Mercedes ML 250 BlueTEC and 350 BlueTEC engines last-
Short summary: Properly maintained OM651 and OM642 BlueTEC engines routinely reach 150,000-200,000 miles before major work. However, BlueTEC emissions components (AdBlue, DPF, EGR) may require attention from 60,000 miles.
- OM651 (250 BlueTEC): 150,000-200,000+ miles with regular servicing
- OM642 (350 BlueTEC): 150,000-200,000+ miles with proper maintenance
- Timing chain tensioner gasket issues may appear from 40,000 miles
- AdBlue/SCR system faults can occur from 60,000 miles
Question 5Is it worth replacing the engine in my Mercedes ML 250 BlueTEC or 350 BlueTEC-
Short summary: Yes, if the M Class is otherwise in good condition with no rust or major transmission faults. A rebuilt OM651 costs £2,500-£3,500 - far less than replacing an £8,000-£20,000 vehicle. The ML 350 BlueTEC's higher value (£10,000-£20,000) makes replacement even more financially justifiable.
- ML 250 BlueTEC values: £8,000-£16,000 depending on year, mileage and condition
- ML 350 BlueTEC values: £10,000-£20,000 - premium SUV residual values remain strong
- Rebuilt engine with upgraded components fixes original weak points
- Supply & fit typically £3,300-£6,300 depending on engine code
- New engine includes 12-month unlimited mileage warranty
Question 6What oil does my Mercedes ML 250 BlueTEC or 350 BlueTEC need-
Short summary: Mercedes-Benz specifies low-SAPS oil meeting MB 229.51 or 229.52 - typically 5W-30. The OM651 requires approximately 6.5 litres; the OM642 V6 requires approximately 8.5 litres.
- OM651 (250 BlueTEC): MB 229.51/229.52 5W-30 low-SAPS - protects DPF and AdBlue systems
- OM642 (350 BlueTEC): MB 229.51/229.52 5W-30 low-SAPS - 8.5L capacity
- Never use non-approved oil - can cause DPF and AdBlue system damage
- Change every 10,000 miles or 12 months - stretched intervals cause timing chain and emissions issues
Why Choose UsCompare Mercedes M Class 250 BlueTEC/350 BlueTECEngine PricesToday
500+ BlueTEC diesel engines supplied through our network
12-Month Warranty on every rebuilt ML 250 BlueTEC and 350 BlueTEC engine
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supply & fit available for OM651 and OM642
Comparing quotes for your Mercedes ML 250 BlueTEC or 350 BlueTEC 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 OM651 four-cylinder and OM642 V6 BlueTEC engines inside out. Whether you need a used engine, a reconditioned unit, or a full rebuilt engine with upgraded timing components, oil cooler seals, and emission system parts, 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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