How much does a Mercedes E Class 350 CDI engine replacement cost in the UK-

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.

What are the signs of oil cooler seal failure in an E Class 320 / 350 CDI-

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.

Is it worth replacing the engine on an older E Class 320 CDI-

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+.

What causes the OM642 timing chain to fail on E Class 350 CDI models-

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.

What is the difference between the OM648 and OM642 engines in the E Class-

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.

How long does a Mercedes E Class 350 CDI engine last-

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.

Mercedes E Class 320 / 350 CDI SPECIALISTS

Mercedes Benz E Class 320 / 350 CDI Engine Replacement Compare 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.

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Mercedes Benz E Class 320 / 350 CDI Engine

from£1,500 to £5,500

Usedfrom £1,200
Reconditionedfrom £1,800
Common codesOM642.920, OM642.850, OM642.858

Mercedes Benz e-class 320 / 350 CDI Used Engine — OM648.961

Mercedes Benz e-classUsed Engine — OM648.961

Mercedes Benz e-class 320 / 350 CDI Reconditioned Engine — OM648.961

Mercedes Benz e-classReconditioned Engine — OM648.961

Mercedes Benz e-class 320 / 350 CDI Rebuilt Engine — OM648.961

Mercedes Benz e-classRebuilt Engine — OM648.961

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How it works

3 Simple Steps to Finding the Right Replacement Engine

Clear information first, then the right engine and specialist for your exact vehicle.

Variant History

Mercedes 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.

**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

Every engine fitted to the Mercedes E Class 320 CDI and 350 CDI is covered below, with UK rebuilt pricing and known failure points.

Engine Codes & Pricing

Mercedes Benz E Class 320 CDI / 350 CDI Engine Codes Specifications & Replacement Cost

Find your exact engine code, specs and UK replacement cost guide.

OM648.961 — 3.2L Diesel (2002-2005)

Power Output: 150 kW (204 hp) at 4,200 rpm
Torque: 500 Nm at 1,800 rpm
Years Fitted: 2002-2005 (W211 E-Class)

Can’t find your exact engine code?-> Get quotes for OM648 Mercedes E Class 320 CDI engine replacement

-> Get quotes for OM648 Mercedes E Class 320 CDI engine replacement

Common Problems

Mercedes E Class 320 CDI / 350 CDI Engine Problems Repair Cost vs Replacement

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.

Common failure points and repair options

Oil Cooler Seal Failure

Affected: 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.

Repair options

Repair tier	Dealer price	Specialist price
Intermediate - Oil Cooler Seal Replacement	£1,200-£1,800	£700-£1,100
Major - Oil Cooler Seals Plus Ancillaries	£1,800-£2,500	£1,200-£1,800
Full Replacement - Rebuilt Engine	£5,500-£8,000	£2,800-£5,500

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.

-> Compare rebuilt OM642 Mercedes E Class 320 / 350 CDI engine prices

Timing Chain Rattle

Affected: Mercedes E Class 320 CDI / 350 CDI (OM642, 2005-2016)
Typical failure mileage: 80,000 - 120,000 miles

Root cause

The timing chain tensioner loses hydraulic pressure overnight, causing a rattling noise on cold start for 2-4 seconds until oil pressure builds. Later OM642 engines (2009/2010 onwards) seem to suffer from timing chain issues more frequently. Extended oil change intervals and stop-start operation accelerate wear.

Repair options

Repair tier	Dealer price	Specialist price
Preventative - Timing Chain Tensioner	£800-£1,200	£400-£700
Major - Full Timing Chain Replacement	£1,800-£3,000	£1,200-£2,000
Full Replacement - Rebuilt Engine	£5,500-£8,000	£2,800-£5,500

Our recommendation

The cold-start rattle is your early warning - don't ignore it. A specialist tensioner replacement at £400-£700 is significantly cheaper than the £1,200+ full chain replacement if the chain stretches further. If the chain has jumped and bent valves, a rebuilt engine with warranty typically offers better value than a dealer-led rebuild.

-> Get OM642 Mercedes E Class 320 / 350 CDI timing chain quotes

Swirl Flap & DPF Issues

Affected: Mercedes E Class 320 CDI / 350 CDI (OM642, 2005-2016)
Typical failure mileage: 80,000 - 150,000 miles

Root cause

The intake manifold swirl flaps use plastic linkage rods that break over time. DPF blockages occur on urban-driven examples where regeneration cycles cannot complete. A clogged DPF can cause excess heat and pressure buildup, potentially damaging the turbo.

Repair options

Repair tier	Dealer price	Specialist price
Minor - Swirl Flap Linkage Repair	£400-£700	£200-£400
Major - Intake Manifold Replacement	£600-£1,000	£400-£700
Intermediate - DPF Cleaning/Replacement	£600-£1,200	£400-£800

Our recommendation

Swirl flap linkage failure is a well-known OM642 issue - the aftermarket metal repair kit at £200-£400 is a permanent fix that addresses the original design flaw. For DPF issues, regular motorway driving to allow regeneration cycles is the best prevention. If you see DPF warning lights, get it diagnosed promptly - a £400-£800 DPF clean is far cheaper than the £2,000+ turbo replacement that a blocked DPF can cause.

-> Get OM642 Mercedes E Class 320 / 350 CDI swirl flap and DPF quotes

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 Mercedes E Class 320 / 350 CDI Engine Replacement Prices Now ->

FAQ

Mercedes E Class 320 CDI / 350 CDI Engine ReplacementFrequently Asked Questions

Everything Mercedes Benz E Class 320 / 350 CDI owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

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

-> Compare Mercedes E Class 350 CDI engine replacement costs by entering your reg now

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

-> Get quotes for OM642 oil cooler seal replacement before it's too late

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+

-> Compare rebuilt Mercedes E Class 320 CDI engine prices for your mileage and budget

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

-> Get quotes for OM642 timing chain replacement before it's too late

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

-> Find the correct Mercedes E Class engine for your exact chassis and engine code

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

-> Compare Mercedes E Class 350 CDI engine replacement quotes - be ready when the time comes

Why Choose Us

Compare Mercedes E Class 320 / 350 CDI Engine Prices Today

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.

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12-Month12-Month Warranty on every rebuilt OM642 engine

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Compare quotes from trusted UK Mercedes Benz E Class 320 / 350 CDI engine specialists with warranty-backed rebuilt, reconditioned and used options nationwide.

Mercedes Benz E Class 320 / 350 CDI Engine Replacement Compare Prices & Get Quotes

Get your free Mercedes Benz e-class 320 / 350 CDI engine quotes

3 Simple Steps to Finding the Right Replacement Engine

Mercedes Benz E Class 320 CDI / 350 CDI Engine History & Specs at a Glance

Mercedes Benz E Class 320 CDI / 350 CDI Engine Codes Specifications & Replacement Cost

OM648.961 — 3.2L Diesel (2002-2005)

Mercedes E Class 320 CDI / 350 CDI Engine Problems Repair Cost vs Replacement

Oil Cooler Seal Failure

Timing Chain Rattle

Swirl Flap & DPF Issues

Don't Let Engine Failure Write Off Your Mercedes E Class 320 CDI or 350 CDI

Mercedes E Class 320 CDI / 350 CDI Engine ReplacementFrequently Asked Questions

Compare Mercedes E Class 320 / 350 CDI Engine Prices Today