Mercedes Benz E Class 320 / 350 CDI Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz E Class 320 CDI and 350 CDI engine specialists. Compare prices on reconditioned, rebuilt and used OM642 V6 diesel engines - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £1,500 to £5,500
Used from £1,200 · Reconditioned from £1,800 · Common codes: OM642.920, OM642.850, OM642.858, OM648.961
From £1,200
Tested, bare/short engine
From £1,800
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
Secure enquiry - no spam, no pressure. Genuine quotes only from vetted UK Mercedes E Class diesel specialists.
3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz E Class 320 / 350 CDI Replacement Engineto Finding the Best Mercedes Benz E Class 320 / 350 CDI Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz E Class 320 CDI / 350 CDI - Engine History & Specs at a Glance
The E 320 CDI and E 350 CDI badges represented Mercedes-Benz's flagship six-cylinder diesel offerings across the W211 and W212 E-Class generations. The E 320 CDI used the legendary OM648 3.2-litre straight-six in early W211 models before transitioning to the OM642 3.0-litre V6 in 2005 - a engine that would go on to power the E 350 CDI through the W212 era. The OM642 V6 is known for effortless torque delivery but carries the infamous oil cooler seal failure that has become the defining repair of this engine family.
Variant HistoryMercedes Benz E Class 320 CDI / 350 CDI - Engine History & Specs at a Glance
The E 320 CDI and E 350 CDI badges represented Mercedes-Benz's flagship six-cylinder diesel offerings across the W211 and W212 E-Class generations. The E 320 CDI used the legendary OM648 3.2-litre straight-six in early W211 models before transitioning to the OM642 3.0-litre V6 in 2005 - a engine that would go on to power the E 350 CDI through the W212 era. The OM642 V6 is known for effortless torque delivery but carries the infamous oil cooler seal failure that has become the defining repair of this engine family.
Mercedes Benz E Class 320 CDI / 350 CDI
Fuel TypeDiesel
Engine Size Range3.0L - 3.2L (2,987 cc - 3,222 cc)
Power Output Range204-265 hp across the variant's historyEngine History Timeline
**1999-2002** - W210 E 320 CDI launched with OM613 straight-six diesel (earliest generation)
**2002** - W211 E 320 CDI launched with OM648.961 3.2-litre straight-six diesel 150 kW (204 hp), 500 Nm - the last of the legendary inline-six diesels
**2005** - OM648 production ends; OM642 3.0-litre V6 diesel introduced replacing the straight-six
**2005-2009** - W211 E 320 CDI with OM642.920 V6 diesel 165 kW (221 hp), 510 Nm
**2009** - W212 generation launched; E 350 CDI badge replaces E 320 CDI
**2009-2016** - W212 E 350 CDI with OM642.850 (231 hp) and OM642.858 (265 hp)
**2014** - BlueTEC branding introduced on later E 350 CDI models with AdBlue emissions treatment
**2016** - W212 production ends; OM654 replaced OM642 in W213 generation
Key Specs Snapshot
Fuel TypeDieselEngine Size Range3.0L - 3.2L (2,987 cc - 3,222 cc)Power Output Range204-265 hp across the variant's historyYears Produced2002-2016Every engine fitted to the Mercedes E Class 320 CDI and 350 CDI is covered below, with UK rebuilt pricing and known failure points.
Mercedes Benz E Class 320 CDI / 350 CDI Engine Codes - Specifications & Replacement CostMercedes Benz E Class 320 CDI / 350 CDI Engine Codes - Specifications & Replacement Cost
3.2L Diesel (2002-2005)
Power Output150 kW (204 hp) at 4,200 rpmTorque500 Nm at 1,800 rpmYears Fitted2002-2005 (W211 E-Class)
Compatible Trim Levels
- E 320 CDI (W211, 2002-2005)
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
£1,700-£2,800
Rebuilt
Full teardown, upgraded internals
£2,200-£3,500
Common Failure
Injector seal failure ("Black Death") - the OM648 is particularly known for this issue. Copper sealing washers degrade over time, allowing combustion gases to leak past and create carbon deposits that can seize injectors in the cylinder head. The OM648 is considered one of Mercedes' most durable diesel engines when properly maintained.
The OM642 V6 engine that powers the majority of E Class 320 CDI and 350 CDI models is renowned for its effortless torque and refinement - but the infamous oil cooler seal failure has become the defining repair of this engine family. Timing chain wear, swirl flap failure, and DPF issues also feature prominently. Every rebuilt engine supplied through EnginesMarket includes upgraded components designed to address the original failure point, plus a minimum 12-month unlimited mileage warranty. Below, we break down what these failures cost to fix and when replacement is the smarter option.
The OM642 Achilles Heel in the E Class 320 / 350 CDI
Affected Vehicles
Mercedes E Class 320 CDI / 350 CDI (OM642, 2005-2016)
Typical Failure Mileage
70,000 - 100,000 miles
Root Cause
The oil cooler sits in the engine Vee and uses rubber seals that harden with heat cycles. When they fail, oil leaks into the Vee, runs down the block, and can eventually mix with coolant. The seals themselves cost as little as £5, but the labour is extensive - the intake manifold and numerous ancillaries must be removed to access them.
Why It Happens
The oil cooler sits in the engine Vee and uses rubber seals that harden with heat cycles. When they fail, oil leaks into the Vee, runs down the block, and can eventually mix with coolant. The seals themselves cost as little as £5, but the labour is extensive - the intake manifold and numerous ancillaries must be removed to access them.
Dealer (parts + labour)
£1,200-£1,800
Specialist (parts + labour)
£700-£1,100
What it involves
Removal of intake manifold, replacement of cooler seals, clean oil residue, refill fluids
Suitability
70,000-100,000 miles; effective if caught early
1 - 2 daysDealer (parts + labour)
£1,800-£2,500
Specialist (parts + labour)
£1,200-£1,800
What it involves
Seal replacement plus new turbo oil feed lines, injector seals, and intake gaskets
Suitability
100,000+ miles; addresses multiple OM642 leak points
1 - 2 daysDealer (parts + labour)
£5,500-£8,000
Specialist (parts + labour)
£2,800-£5,500
What it involves
Supply & fit of rebuilt OM642 with upgraded Viton oil cooler seals and new turbo lines
Suitability
When oil has emulsified coolant or damaged bearings
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 |
|---|---|---|---|---|---|
 Intermediate - Oil Cooler Seal Replacement Minor | £1,200-£1,800 | £700-£1,100 | Removal of intake manifold, replacement of cooler seals, clean oil residue, refill fluids | 70,000-100,000 miles; effective if caught early | 1 - 2 days |
 Major - Oil Cooler Seals Plus Ancillaries Best Value | £1,800-£2,500 | £1,200-£1,800 | Seal replacement plus new turbo oil feed lines, injector seals, and intake gaskets | 100,000+ miles; addresses multiple OM642 leak points | 1 - 2 days |
Full Replacement - Rebuilt Engine Best Value | £5,500-£8,000 | £2,800-£5,500 | Supply & fit of rebuilt OM642 with upgraded Viton oil cooler seals and new turbo lines | When oil has emulsified coolant or damaged bearings | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical W211 E 320 CDI is worth £2,000-£4,500 depending on condition and mileage; a W212 E 350 CDI commands £4,000-£10,000【INDUSTRY ESTIMATE】. If the vehicle is worth under £3,000, a used engine or minor seal repair is usually the pragmatic choice. For W212 cars worth £5,000+, a rebuilt engine with upgraded seals and warranty can be justified if the rest of the car is sound.
Our Recommendation
Our Recommendation
If caught early with no oil-coolant emulsion, specialist seal replacement at £700-£1,100 is all you need. Once oil has blocked the turbo feed lines or emulsified coolant has damaged bearings, a rebuilt engine with upgraded seals becomes the most cost-effective long-term solution - especially on a high-value E 350 BlueTEC. Don't ignore oil drips under the engine bay - that's the telltale sign.
Don't Let Engine Failure Write Off Your Mercedes E Class 320 CDI or 350 CDI
Whether your E Class 320 CDI or 350 CDI is suffering from oil cooler seal failure, timing chain rattle, or swirl flap issues, EnginesMarket makes it simple to compare prices from trusted UK Mercedes specialists. Every rebuilt engine in our network includes upgraded components designed to address the original failure point - plus a minimum 12-month unlimited mileage warranty and nationwide delivery. Compare prices, choose a specialist, and get back on the road without the main dealer premium.
Compare rebuilt OM642 Mercedes E Class 320 / 350 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 E Class 320 CDI or 350 CDI. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Mercedes E Class 320 CDI / 350 CDI Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes E Class 350 CDI engine replacement cost in the UK-
Short summary: Supply-only rebuilt OM642 engines range from £2,200 to £5,500 depending on engine code and condition. With specialist fitting, budget £2,600-£6,300 total.
- OM642.920 (E 320 CDI, 221 hp, 2005-2009): rebuilt £2,200-£3,500
- OM642.850 (E 350 CDI, 231 hp, 2009-2015): rebuilt £2,500-£4,200
- OM642.858 (E 350 CDI 4MATIC, 265 hp, 2011-2016): rebuilt £2,800-£5,500
- Labour adds £400-£800 depending on specialist location
Question 2What are the signs of oil cooler seal failure in an E Class 320 / 350 CDI-
Short summary: Oil drips under the engine bay, a burning oil smell after driving, and oil pooling in the engine Vee are the classic signs. A "Check Oil Level" message may also appear.
- Oil drips on the undertray or ground - check the rear of the engine tray
- Burning oil smell, particularly after motorway driving
- Oil pooling in the engine valley (Vee) between the cylinder banks
- Oil cooler seal replacement at a specialist costs £700-£1,100
Question 3Is it worth replacing the engine on an older E Class 320 CDI-
Short summary: Yes, if the car is otherwise sound. W211 E 320 CDI examples with good service history command £2,000-£4,500 used, making replacement viable.
- A quality rebuilt OM642 costs £2,200-£3,500 supply only
- The OM642 V6 is a desirable engine with effortless torque delivery
- A replacement engine with warranty costs less than financing a newer car
- Specialist fitting adds £400-£800, not dealer rates of £1,500+
Question 4What causes the OM642 timing chain to fail on E Class 350 CDI models-
Short summary: The timing chain tensioner wears over time, particularly when oil changes exceed 10,000 miles. Cold-start rattle is the early warning sign.
- Tensioner wear typically occurs between 80,000-120,000 miles
- Cold-start rattle that disappears after 2-4 seconds is the early warning
- Tensioner replacement at a specialist costs £400-£700; full chain replacement £1,200-£2,000
- Later OM642 engines (2009/2010 onwards) seem more prone to timing chain issues
Question 5What is the difference between the OM648 and OM642 engines in the E Class-
Short summary: The OM648 is a 3.2-litre straight-six diesel (2002-2005) - the last of Mercedes' legendary inline-six diesels. The OM642 is a 3.0-litre V6 diesel (2005-2016) that replaced it, featuring a more compact 72-degree V configuration.
- OM648: cast iron block, straight-six, 204 hp, 500 Nm - renowned for durability
- OM642: all-aluminium V6, 221-265 hp, 510-620 Nm - more powerful but has oil cooler seal issues
- Both are common-rail diesel engines with variable geometry turbochargers
- The OM648 is generally considered more durable; the OM642 offers better performance
Question 6How long does a Mercedes E Class 350 CDI engine last-
Short summary: With proper maintenance and 8,000-10,000 mile oil changes, OM642 engines regularly reach 200,000-300,000 miles. Well-maintained examples can exceed 500,000 km.
- OM642 bottom ends are robust when properly maintained
- Oil cooler seal replacement at 70k-100k miles is the key maintenance item
- Timing chain inspection at 80k-100k miles is recommended
- Short oil change intervals (8k miles) are critical for longevity
Why Choose UsCompare Mercedes E Class 320 / 350 CDIEngine PricesToday
500+ E Class V6 diesel engines supplied through our network
12-Month Warranty on every rebuilt OM642 engine
Nationwide UK delivery
supply & fit available
Comparing quotes for your Mercedes E Class 320 CDI or 350 CDI engine replacement is free, no-obligation, and specific to your exact engine code and model year. Enter your registration above to get tailored prices from vetted UK specialists - whether you need a used OM648, a reconditioned OM642.920, a rebuilt OM642.858, or a fully remanufactured unit with warranty and fitting. Don't pay main dealer premiums - compare, choose, and get back on the road with confidence.
Enter your registration
and get matched with verified Mercedes Benz E Class 320 / 350 CDI specialists.