Mercedes-Benz C-Class C300d Engine Replacement — Compare Prices & Get Quotes
Get quotes today from trusted UK Mercedes-Benz C300d specialists. Compare reconditioned, rebuilt and used 2.0-litre four-cylinder turbo-diesel engines — OM654 variants across the W205 and W206 generations — supply & fit available nationwide.
The C300d THROUGH TIME — Era Map
Four generations. Four eras. One guide to reliability, costs and what really matters.
Era Note
Fourth-generation 2.0L diesel — 261 bhp, 550 Nm; reliable but timing chain, injector seals and EGR/DPF need attention
Why use this era map?
This table is the single source every other section on this page matches — Sections 2, 4 and 6 reference it rather than restating conflicting figures.
Mercedes-Benz C-Class C300d Engine Replacement Costs
Figures above reflect current C300d replacement costs. This badge spans only one engine era — see the Era Map above.
Labour estimate: Fitting a C300d engine typically takes 10–14 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).
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C-Class C300d — Repair, Buy, or Replace?
Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.
Can It Be Repaired?
Buying This C300d? Check These First
Buy If
- Post-2020 OM654 M (MHEV) with improved timing chain components
- Full Mercedes service history with regular oil changes (critical for chain longevity)
- No cold-start rattling (timing chain health)
- EGR cooler and DPF recently serviced
- AdBlue system functioning correctly (no warning lights)
- Evidence of regular longer runs (DPF health)
Avoid If
- Cold-start rattling and no timing chain history — assume it's overdue
- No service history — the OM654 is sensitive to oil quality
- Short-journey ownership history — DPF and EGR issues likely
- Unexplained power loss or limp mode — EGR cooler or DPF issues
- Engine warning light with no diagnosis — may indicate timing, EGR or AdBlue problems
Closing Verdict
The C300d is Mercedes' top-spec 2.0-litre diesel in the C-Class range — a 261 bhp, 550 Nm four-cylinder that delivers exceptional performance and refinement. The OM654 is a significant improvement over the OM651 — lighter, more efficient and quieter. With proper servicing, these units regularly exceed 180,000 miles. However, early OM654 units have reported timing chain issues, EGR cooler vacuum diaphragm failures, injector seal leaks, and DPF/AdBlue system problems. With typical C300d values ranging from £25,000 (W205) to £40,000+ (W206), an engine replacement is a major financial commitment — a well-maintained post-2020 OM654 M with full service history is the safest choice.
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Buying Checklist
Before you buy a used Mercedes-Benz C-Class C300d (or before you commit to an engine replacement), check these:
Cold Start — Listen for rattling or clattering (timing chain warning) — see the map above
Service History — Including regular oil changes (critical for timing chain longevity)
EGR Cooler — Check for any loss of power or warning lights; vacuum diaphragm failures are common
DPF Regeneration — Check history; short journeys accelerate wear
AdBlue System — Check for warning lights or AdBlue faults
Injector Health — Check for smooth idle; any rough running may indicate injector seal issues
Engine Warning Light — Have codes read; unresolved issues may indicate timing, EGR, DPF or AdBlue problems
MOT History — Check for emissions-related failures
Buy smart. Drive with confidence.
A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.
Engine Codes
This table's rows match Section 1B's Era Map exactly.
OM654 (2.0L diesel)
Technical Specs
OM654 — C300d→ Compare C300d engine prices for your C-Class
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Market Intelligence
Most Common Failure
EGR cooler vacuum diaphragm failure and timing chain wear (early OM654) — the most frequent C300d enquiries
Average Enquiry Mileage
40,000
–70,000 miles
[PATTERN DATA]
Average Replacement Cost
£6,000
–£7,000 reconditioned, supply only
[PLACEHOLDER]
Most Requested Engine Code
OM654
[PATTERN DATA]
Peak Enquiry Season
Winter — cold starts expose timing chain wear; EGR/DPF issues year-round
[PATTERN DATA]
Regional Demand
PATTERN DATA
Regional Demand Breakdown
Frequently Asked Questions
All prices are indicative UK market ranges based on historical quote data from our network of engine specialists. Actual costs vary by variant, engine condition, damage severity and workshop location. Use our free comparison tool to get tailored quotes. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty — always confirm terms with your chosen supplier.
Why UK Mercedes-Benz C-Class C300d Owners Trust MercedesEngine.uk
Trusted C300d Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real C300d owners, as part of the Engine Finders network, covering the OM654 across the W205 and W206 generations.
Compare C300d Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit. We cover the 2.0-litre four-cylinder diesel specifically, with specialists who understand the OM654 timing chain vulnerabilities, EGR cooler issues, and the unique requirements of the C300d.
UK Engine Replacement Services for C300d
supply-only or full supply & fit available nationwide, covering every generation of this badge since 2018, with a 12-month warranty as standard across our network.
Find the best Mercedes-Benz C-Class C300d engine replacement UK owners rely on. Compare prices from trusted specialists on EnginesMarket today and get your C-Class back on the road with confidence.
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No hidden fees
No Obligation
Get quotes with zero pressure
UK Specialists
20+ vetted experts
12-Month Warranty
As standard
Nationwide Delivery
Supply & fit available