Is the Mercedes C350 / C400 Petrol engine reliable?

It depends which generation your car is. The W204's M272 (2007–2014) is a characterful naturally aspirated V6, but early cars (pre‑2008) have a notorious balance shaft weakness. The W205's M276 twin‑turbo (2015–2021) has earned a strong reliability reputation but is sensitive to maintenance neglect — timing chain tensioner rattle and oil leaks are the main watchpoints. Check the Era Map above for your specific car.

What are the common problems with the C350 / C400 Petrol engine?

M272 (W204): balance shaft gear wear (pre‑2008 engines), timing chain issues, and intake manifold problems. M276 (W205): timing chain tensioner rattle (cold start), oil leaks (valve covers, turbo lines, camshaft sensors), and turbocharger wear. Both engines demand regular maintenance.

Is it worth replacing a C350 / C400 Petrol engine, or should I scrap the car?

Depends on vehicle value and generation. A W204 C350 is a £4,000–£10,000 vehicle — a £4,000–£4,500 recon is 40–113% of the car's value. For lower‑value examples (sub‑£5,000), replacement may exceed our 70% Mercedes scrap threshold. A W205 C400 is a £10,000–£20,000+ vehicle — a £5,000–£6,000 recon is 25–60% of the car's value; replacement is viable in most cases. Evaluate carefully based on your car's generation and condition.

How do I find my Mercedes C350 / C400 Petrol engine code?

Listed on the VIN plate and vehicle documentation. The C350 covers M272 (W204, 2007–2014) and the C400 covers M276 (W205, 2015–2021). Tell us your registration date and we'll confirm which one you have for free.

Can I prevent the common failures on a C350 / C400 Petrol?

On M272 (W204): check the engine number — if it's within the affected range (up to 2729...30468992), budget for balance shaft replacement. On M276 (W205): regular oil changes with 5W‑40 oil on the 'severe schedule' (5,000 miles) are essential. Have the timing chain tensioners and check valves inspected at the first sign of cold‑start rattle. Address oil leaks promptly to prevent wiring harness damage. At the first sign of rattle, vibration or oil leaks, book an inspection immediately.

Mercedes C‑Class C350 / C400 Petrol2007–2021M272 / M276

Mercedes C‑Class C350 / C400 Petrol Engine Replacement — Compare Prices & Get Quotes

The C350 and C400 badges represent the performance‑oriented petrol V6s of the C‑Class — the W204's 3.5‑litre M272 and the W205's 3.0‑litre twin‑turbo M276. Get quotes from trusted UK specialists today.

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Mercedes C350 / C400 Petrol Engines — from £2,000 to £8,000M272 / M276

Mercedes C350 / C400 Petrol Engines — from £2,000 to £8,000· M272 / M276

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The C350 / C400 PETROL THROUGH TIME — Era Map

Four generations. Four eras. One guide to reliability, costs and what really matters.

GenerationYearsEngine CodeReliabilityRecon CostEra Note

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.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Mercedes C‑Class C350 / C400 Petrol Engine Replacement Costs

Supply Only£3,500–£6,500

Fitted (Indie)£4,800–£8,000

Warranty12–24 months

Best ForMost owners — best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£2,000–£3,500£3,000–£4,8001–6 monthsBudget priority; older W204

Reconditioned Engine£3,500–£6,500£4,800–£8,00012–24 monthsMost owners — best cost/warranty balance

Rebuilt Engine£5,000–£8,000£6,300–£9,60012–24 monthsLong-term ownership; 3+ year horizon

Main Dealer New£7,000–£10,000 (where available)£8,300–£11,80024–36 monthsInsurance jobs, warranty claims

Figures above reflect the range across both generations; specific costs vary by era — see the Era Map above.

Labour estimate: Fitting a C350 / C400 engine typically takes 12–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). V6 engines require more disassembly than four‑cylinder units.

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Common Problems

1. Balance Shaft Gear Wear (M272 — W204, Pre‑2008)

Symptoms: Rattling or grinding noise from the front of the engine, rough idle, increased engine vibration, engine warning light (P0016/P0017 codes), metal debris in the oil.

Typical mileage: 60,000–100,000 miles

Repair cost: £2,000–£4,500 (balance shaft and timing gear replacement)

Replacement cost: £3,500–£5,500 (full engine replacement if damage is extensive)

🔴 Immediate - if you hear rattling or grinding, book an inspection today

Our recommendation:

Early M272 engines (up to engine number 2729...30468992) have a balance shaft gear made from soft metal that wears prematurely. If this gear fails, metal debris can circulate through the engine, causing catastrophic damage. Check the engine number before buying a W204 C350 — if it falls within the affected range, budget for balance shaft replacement or walk away. A replacement balance shaft kit with an updated timing gear is available.

1. Balance Shaft Gear Wear (M272 — W204, Pre‑2008)

Symptoms: Rattling or grinding noise from the front of the engine, rough idle, increased engine vibration, engine warning light (P0016/P0017 codes), metal debris in the oil.

Typical mileage: 60,000–100,000 miles

Repair cost: £2,000–£4,500 (balance shaft and timing gear replacement)

Replacement cost: £3,500–£5,500 (full engine replacement if damage is extensive)

🔴 Immediate - if you hear rattling or grinding, book an inspection today

Our recommendation:

2. Timing Chain Tensioner Rattle (M276 — W205 C400)

Symptoms: Rattling noise on cold start (2–3 seconds), rattling or clattering from the front of the engine, poor timing performance, misfires.

Typical mileage: 60,000–120,000 miles

Repair cost: £800–£2,500 (tensioners, check valves and camshaft adjusters)

Replacement cost: £4,500–£7,500 (full engine replacement if chain jumps)

🔴 Immediate - if you hear rattle, book an inspection today

Our recommendation:

The M276's timing chain tensioners are a known weak point — they can lose oil pressure overnight, causing a brief rattle on cold start. This can progress to timing chain stretch and camshaft adjuster wear. Mercedes issued a technical service bulletin (LI05.10‑P‑056435) recommending the installation of check valves and updated chain tensioners. Regular oil changes with 5W‑40 oil on the "severe schedule" (5,000 miles) are essential. At the first sign of cold‑start rattle, have the tensioners and check valves inspected.

3. Oil Leaks — Valve Covers, Turbo Lines & Camshaft Sensors (M276 — W205 C400)

Symptoms: Oil spots under the vehicle, burning oil smell, oil residue on the engine, oil leaking into the wiring harness.

Typical mileage: 50,000–90,000 miles

Repair cost: £400–£1,200 (valve cover gaskets, turbo oil lines, camshaft sensor seals)

Replacement cost: N/A — repair only

🟡 Monitor - book inspection soon

Our recommendation:

Oil leaks are a prevalent issue on the M276 engine. Common sources include valve cover gaskets, turbocharger oil lines, and camshaft position sensors that can leak oil into the wiring harness. If you notice oil spots or a burning smell, have the engine inspected. Replacing gaskets and seals promptly prevents more serious damage and expensive wiring harness repairs.

Weighing Your Options?

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C350 / C400 Petrol — 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.

C350 / C400 Petrol — 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?

ProblemRepairable?Typical CostWhen It Makes SenseBalance shaft wear (M272 pre‑2008)✅ Yes£2,000–£4,500Catch it early — before metal debris causes engine failureTiming chain tensioner rattle (M276)✅ Yes£800–£2,500Install check valves and updated tensioners — permanent fixOil leaks (M276)✅ Yes£400–£1,200Routine maintenance — do preventativelyTurbocharger failure (M276)✅ Yes£1,500–£3,500Replace or rebuild — cheaper than collateral damageSevere engine damage (balance shaft failure / chain jump)❌ Usually NoEngine replacementLittle left to salvage — replacement is the only option

Buying This C350 / C400 Petrol? Check These First

Buy If

M272 (W204): post‑2008 engine (outside affected engine number range) or balance shaft already replaced
M276 (W205): no cold‑start rattle — timing chain tensioners in good condition
No oil leaks — valve covers, turbo lines and camshaft sensors dry
Full Mercedes service history with regular oil changes

Avoid If

Pre‑2008 M272 with no balance shaft history — walk away
Cold‑start rattle on M276 with no tensioner history — timing chain issues likely
Oil leaks with no diagnosis — potentially expensive
Poor service history — both engines are sensitive to neglect

Closing Verdict

The C350 and C400 petrol V6s are the performance heart of the C‑Class range — the W204's M272 is a characterful naturally aspirated V6, but early cars have a notorious balance shaft weakness. The W205's M276 twin‑turbo is more modern and responsive, but timing chain tensioner rattle and oil leaks are the main watchpoints. Buy on full service history, check the engine number on M272 cars, and never ignore a cold‑start rattle.

Don't guess.Get the right engine at the right price.

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Buying Checklist

Before you buy a used Mercedes C‑Class C350 / C400 Petrol (or before you commit to an engine replacement), check these:

Engine Number (M272) — Check if within affected balance shaft range (up to 2729...30468992)

Cold Start — Listen for rattling or grinding; balance shaft (M272) or timing chain tensioner (M276) indicator

Oil Leaks — Check under the car and around the engine; valve covers, turbo lines and camshaft sensors

Service History — including which generation (W204 or W205) and confirmed oil‑change intervals

Turbo Health (M276) — Listen for whistling or whining; turbo failure indicator

Engine Vibration — Check for rough idle or increased vibration; balance shaft wear indicator (M272)

Oil Consumption — Does it use more than 1L per 1,000 miles?

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.

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.

M272 (3.5 V6 NA)

Years2007–2014

Power302 hp (225 kW) @ 6,500 rpm; 273 lb‑ft (370 Nm) @ 3,500 rpm

2025 Enquiries— (pattern data)

Avg. Recon Cost£3,500–£5,500【PLACEHOLDER】

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

M272 (3.5 V6 NA)2007–2014302 hp (225 kW) @ 6,500 rpm; 273 lb‑ft (370 Nm) @ 3,500 rpm— (pattern data)£3,500–£5,500【PLACEHOLDER】

M276 (3.0 V6 twin‑turbo)2015–2021329 hp (245 kW) @ 5,500 rpm; 354 lb‑ft (480 Nm) @ 1,400–4,000 rpm— (pattern data)£4,500–£7,500【PLACEHOLDER】

Technical Specs

M276 3.0 twin‑turbo V6, W205

Displacement2,996 cc

Cylinders6‑cylinder V‑configuration

Compression Ratio10.5:1

Fuel SystemDirect injection

TurbochargerTwin‑turbo (biturbo)

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Market Intelligence

Most Common Failure

M272: balance shaft gear wear (pre‑2008); M276: timing chain tensioner rattle【PATTERN DATA】

Average Enquiry Mileage

60,000

–80,000 miles【PATTERN DATA】

Average Replacement Cost

£4,500

–£5,500 reconditioned, supply only【PLACEHOLDER — confirm vs cost sheet】

Most Requested Engine Code

M276 (W205) — approximately 60% of C350/C400 enquiries【PATTERN DATA】

Peak Enquiry Season

Autumn/Winter — cold starts expose timing chain and balance shaft issues【PATTERN DATA】

Regional Demand

South East18%

London16%

North West (12%)【PATTERN DATA】

Regional Demand Breakdown

18%South East

16%London

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 code, 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.

Find the best Mercedes C‑Class C350 / C400 Petrol engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get back on the road with confidence — from £2,000 for a used unit to £8,000 for a fully rebuilt V6.

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12-Month Warranty

As standard

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