MercedesBenz B Class B180 CDI Engine Replacement - Compare Prices & Get Quotes
Get quotes today from trusted UK Mercedes-Benz B Class B180 CDI engine specialists. Compare prices on reconditioned, rebuilt and used engines for both the W245 (2005-2011) and W246 (2011-2018) generations - supply & fit available across the UK.
Supply & Fit Available
12-Month Warranty
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From £1,800 to £2,800
Used from £900 · Reconditioned from £1,500 · Common codes: OM640.940, OM651.901
From £900
Tested, bare/short engine
From £1,500
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 B Class B180 CDI Replacement Engineto Finding the Best Mercedes-Benz B Class B180 CDI Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes-Benz B Class B180 CDI - Engine History & Specs at a Glance
The Mercedes-Benz B Class B180 CDI entered the UK market in September 2005 as the entry-level diesel in the first-generation W245 range. Powered initially by a 2.0-litre OM640.940 diesel producing 109bhp, the B180 CDI was repositioned in 2011 with the second-generation W246, switching to the 1.8-litre OM651.901 BlueEFFICIENCY unit while retaining the same power output but with improved fuel economy and lower emissions.
Variant HistoryMercedes-Benz B Class B180 CDI - Engine History & Specs at a Glance
The Mercedes-Benz B Class B180 CDI entered the UK market in September 2005 as the entry-level diesel in the first-generation W245 range. Powered initially by a 2.0-litre OM640.940 diesel producing 109bhp, the B180 CDI was repositioned in 2011 with the second-generation W246, switching to the 1.8-litre OM651.901 BlueEFFICIENCY unit while retaining the same power output but with improved fuel economy and lower emissions.
Mercedes-Benz B Class B180 CDI
Fuel TypeDiesel
Engine Size Range1.8L-2.0L
Power Output109bhp (both generations)Engine History Timeline
September 2005 - W245 launch OM640.940 2.0L diesel, 109bhp, 250Nm torque, Euro 4 emissions
July 2005 - Diesel Particulate Filter becomes standard equipment from this date
W245 facelift cosmetic updates only; engine range unchanged
November 2011 - W246 launch OM651.901 1.8L diesel BlueEFFICIENCY, 109bhp, 250Nm torque, Euro 5 emissions
W246 facelift OM651.901 continues, revised styling and interior updates
Key Specs Snapshot
Fuel TypeDieselEngine Size Range1.8L-2.0LPower Output109bhp (both generations)Years Produced2005-2018Every engine fitted to the Mercedes-Benz B Class B180 CDI is covered below, with UK rebuilt pricing and known failure points.
Mercedes-Benz B Class B180 CDI Engine Codes - Specifications & Replacement CostMercedes-Benz B Class B180 CDI Engine Codes - Specifications & Replacement Cost
2.0L Diesel (2005-2011)
Power Output109bhp (80kW) at 4,200rpmTorque250Nm at 1,600-2,600rpmYears Fitted2005-2011 (W245 generation)Displacement1,991ccCompression Ratio18.0:1
Compatible Trim Levels
- B180 CDI
- B180 CDI SE
- B180 CDI Sport
- B180 CDI SE CVT Auto
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£900-£1,500
Reconditioned
Addressed known issues, tested
£1,500-£2,200
Rebuilt
Full teardown, upgraded internals
£1,800-£2,800
Common Failure
Injector failure and turbocharger bearing wear are well-documented on high-mileage OM640 units beyond 100,000 miles. The CVT (Autotronic) transmission fitted to some B180 CDI models has its own reliability concerns.
The Mercedes-Benz B Class B180 CDI is broadly reliable, but both engine families - the OM640.940 in W245 cars and the OM651.901 in W246 models - have well-documented failure points. Timing chain tensioner issues dominate OM651 enquiries, while injector and turbo failures affect higher-mileage OM640 units. Every rebuilt engine supplied through EnginesMarket includes upgraded components designed to address the original failure point, plus a minimum 12-month unlimited mileage warranty.
Why the Mercedes-Benz B Class B180 CDI OM651.901 Wears Prematurely
Affected Vehicles
Mercedes-Benz B Class B180 CDI (OM651.901, 2011-2018, W246)
Typical Failure Mileage
60,000-100,000 miles
Root Cause
The timing chain tensioner loses hydraulic pressure, allowing chain slack and guide rail fracture. On OM651 diesels, the chain is located at the rear of the engine (gearbox side), requiring gearbox removal for replacement. A rattling noise on cold start is the first warning sign.
Why It Happens
The timing chain tensioner loses hydraulic pressure, allowing chain slack and guide rail fracture. On OM651 diesels, the chain is located at the rear of the engine (gearbox side), requiring gearbox removal for replacement. A rattling noise on cold start is the first warning sign.
Dealer (parts + labour)
£1,600-£2,400
Specialist (parts + labour)
£900-£1,400
What it involves
Replace chain, tensioner and guides. No engine removal.
Suitability
60k-80k miles if caught early. Suitable only before chain jumps or guides fail.
1 - 2 daysDealer (parts + labour)
£3,500-£5,000
Specialist (parts + labour)
£2,200-£3,200
What it involves
Remove cylinder head, replace bent valves, guides, full timing set, head gasket.
Suitability
Viable if no piston or bore damage. Labour-intensive.
1 - 2 daysDealer (parts + labour)
£6,000-£8,500
Specialist (parts + labour)
£1,800-£2,800
What it involves
Supply & fit of fully rebuilt engine with upgraded timing components, bench tested, 12-month warranty.
Suitability
Best value when damage extends to pistons, bearings or cylinder head.
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 |
|---|---|---|---|---|---|
 Preventative - Timing Chain & Tensioner Replacement Minor | £1,600-£2,400 | £900-£1,400 | Replace chain, tensioner and guides. No engine removal. | 60k-80k miles if caught early. Suitable only before chain jumps or guides fail. | 1 - 2 days |
 Intermediate - Chain Failure With Valve Damage Best Value | £3,500-£5,000 | £2,200-£3,200 | Remove cylinder head, replace bent valves, guides, full timing set, head gasket. | Viable if no piston or bore damage. Labour-intensive. | 1 - 2 days |
Full Replacement - Rebuilt/Reconditioned Engine Best Value | £6,000-£8,500 | £1,800-£2,800 | Supply & fit of fully rebuilt engine with upgraded timing components, bench tested, 12-month warranty. | Best value when damage extends to pistons, bearings or cylinder head. | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical W246 Mercedes-Benz B Class B180 CDI (2011-2018) is worth approximately £4,000-£8,000 depending on mileage and condition. W245 models (2005-2011) are typically £1,500-£3,500. If your OM651.901 engine has suffered timing chain failure with valve damage, a specialist full engine replacement at £1,800-£2,800 is often more cost-effective than a dealer head rebuild exceeding £3,500 - and delivers a fresh warranty.
Our Recommendation
Our Recommendation
On a W246 B180 CDI, if you hear chain rattle on cold start but the engine still runs smoothly, a specialist preventative chain replacement (£900-£1,400) is excellent value. If the chain has already jumped and valves are bent, compare rebuilt engine prices - a specialist fitted unit at £1,800-£2,800 often costs less than a dealer head rebuild and delivers a fresh warranty.
Don't Let Engine Failure Write Off Your Mercedes-Benz B Class B180 CDI
Engine failure doesn't have to mean the end of the road for your B180 CDI. Whether you're facing timing chain rattle on an OM651.901, injector failure on an OM640.940, or DPF blockages on either generation, EnginesMarket makes it simple to compare prices from trusted UK Mercedes-Benz B Class B180 CDI specialists. Every rebuilt engine includes upgraded components designed to address the original failure point - plus a minimum 12-month unlimited mileage warranty. Compare prices today, choose a vetted specialist, and get back on the road without the main dealer premium.
Compare rebuilt OM651.901 Mercedes-Benz B Class B180 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-Benz B Class B180 CDI. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier.
Mercedes-Benz B Class B180 CDI Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes-Benz B Class B180 CDI engine replacement cost in the UK-
A rebuilt Mercedes-Benz B Class B180 CDI engine typically costs £1,800-£2,800 supply-only, depending on which generation and engine code your car has. OM640.940 (W245, 2.0L) and OM651.901 (W246, 1.8L) are priced similarly for rebuilt units.
- Used engine: £900-£1,600 depending on mileage and condition
- Reconditioned engine: £1,500-£2,400
- Rebuilt engine: £1,800-£2,800 with 12-month warranty
- Fitting adds £400-£800 at a specialist
Question 2What are the signs of timing chain failure in a Mercedes-Benz B Class B180 CDI-
The most common warning sign on OM651.901 (W246) B180 CDI engines is a rattling noise on cold start, lasting 1-3 seconds. This indicates the timing chain tensioner is losing hydraulic pressure.
- Rattling on cold start - the first and most important warning sign
- Engine management light with P0016 or P0017 camshaft/crankshaft correlation codes
- Loss of power, misfire or rough running
- Complete failure leads to chain snap, bent valves and catastrophic engine damage
Question 3Does the Mercedes-Benz B Class B180 CDI have a timing chain or belt-
Both the OM640.940 (W245, 2005-2011) and OM651.901 (W246, 2011-2018) engines in the Mercedes-Benz B Class B180 CDI use a timing chain, not a belt. The OM651.901 chain is located at the rear of the engine (gearbox side), making replacement more labour-intensive than a conventional front-chain layout.
- OM640.940: single roller chain, front-mounted
- OM651.901: single roller chain, rear-mounted
- Neither engine has a cambelt - no scheduled replacement interval, but tensioner wear is common
- Cold-start rattle = tensioner warning - act immediately
Question 4Is it worth replacing the engine on a high-mileage Mercedes-Benz B Class B180 CDI-
For W245 models (2005-2011) worth £1,500-£3,500, a rebuilt engine at £1,800-£2,800 often approaches the car's value. However, if the body and transmission are sound, specialist replacement with 12-month warranty can still be cheaper than buying a comparable replacement car. W246 models (2011-2018, worth £4,000-£8,000) are almost always worth repairing.
- W245 (2005-2011): value £1.5k-£3.5k - borderline economical, evaluate carefully
- W246 (2011-2018): value £4k-£8k - replacement makes sense
- Rebuilt engine (£1.8k-£2.8k fitted) often cheaper than comparable replacement car
- Factory-quality rebuild with upgraded components often outlasts original
Question 5How long do Mercedes-Benz B Class B180 CDI engines last-
Well-maintained OM640.940 and OM651.901 diesel engines regularly reach 180,000-250,000 miles with proper servicing. Timing chain tensioner issues on OM651 are the main factor limiting longevity if not addressed preventatively.
- OM640.940 (W245): 180,000-250,000 miles; injector and turbo failures the main limiters
- OM651.901 (W246): 180,000-250,000 miles; timing chain tensioner the primary concern
- Regular oil changes (every 10,000 miles or annually) essential for both
- Short-trip driving kills DPF - use for longer journeys where possible
Question 6What's the difference between the B180 CDI and B200 CDI engine-
The B180 CDI and B200 CDI share the same engine family in each generation but are tuned differently. In the W245 (OM640), the B180 CDI produces 109bhp while the B200 CDI produces 140bhp from the same 2.0L displacement. In the W246 (OM651.901 vs OM651.930), the B180 CDI delivers 109bhp from 1.8L while the B200 CDI produces 136bhp.
- Same engine family, different state of tune
- B180 CDI: lower power, better fuel economy (50-54mpg)
- B200 CDI: higher power, slightly worse economy
- Replacement engines are not interchangeable without ECU remapping
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