Is the Mercedes SL500 / SL550 / SL560 engine reliable?

It depends on which generation your SL has. The M117 in the R107 is a legendary engine with near‑mythical durability – engines exceeding 250,000 miles are not unusual. The M119 in the early R129 is a masterpiece but has distributor and wiring vulnerabilities. The M113 in the late R129 and early R230 is robust but suffers from sludge and carbon build‑up. The M273 in the facelift R230 has a well‑documented timing chain idler sprocket weakness. The M278 in the R231 is a sophisticated twin‑turbo V8 with oil leak and turbo concerns. Regular oil changes (every 8,000‑10,000 miles) are essential for all these engines.

What are the common problems with the Mercedes SL500 / SL550 / SL560?

On the R107 (M117), the most common issue is timing chain guide wear. On the R129 early (M119), distributor caps and wiring harnesses are the main weaknesses. On the R129 late and R230 early (M113), sludge and carbon build‑up from short trips are the main concerns. On the R230 facelift (M273), the defining weakness is timing chain idler sprocket failure. On the R231 (M278), oil leaks and turbocharger issues are the primary concerns.

Is it worth replacing an SL V8 engine, or should I scrap the car?

Depends on vehicle value and condition. Against a tidy £5,000–£20,000 SL, a £2,500–£6,500 recon is 15‑60% of the car's value – often worth it on well‑maintained examples. If the M273 timing chain idler has failed or the engine has suffered catastrophic failure, a full engine replacement may be necessary. Get a full diagnostic assessment before committing. The SL is a modern classic, so well‑preserved examples may justify the investment.

How do I find my SL's engine code?

The R107 560SL uses the M117.968. The R129 (1990‑1998) SL500 uses the M119.972. The R129 (1998‑2001) and R230 (2001‑2006) SL500 use the M113.963. The R230 facelift (2006‑2011) SL500/SL550 uses the M273.965. The R231 (2012‑2020) SL550 uses the M278.928. The engine code is stamped on the engine block and listed on your V5C. For the M273, check the engine serial number – later engines (above approximately 80,000) are generally safe from the idler sprocket issue.

Can I repair an SL V8 engine issue, or does it need replacement?

Most issues – M117 timing chain guides (if caught early), M119 distributor/wiring issues, M113 sludge, M273 oil leaks and timing chain idler wear (if caught early), M278 oil leaks – are repairable. However, if the M273 idler sprocket has failed or the timing chain has snapped on any engine, a full engine replacement is usually more cost‑effective than a rebuild.

Mercedes SL500 / SL550 / SL5601986–20205 Engine Families

Mercedes SL500 / SL550 / SL560 Engine Replacement — Compare Prices & Get Quotes

Name: Mercedes SL V8 UK Engine Enquiry Data 2025
Creator: MercedesEngine.uk

Get quotes today from trusted UK Mercedes specialists. Compare reconditioned, rebuilt and used M117, M119, M113, M273 and M278 V8 engines for the SL500, SL550 and SL560 — the legendary V8 powerplants that have defined Mercedes' iconic roadster for over three decades. Supply & fit available nationwide.

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Mercedes SL V8 Engines — from £1,500 to £6,500Common codes: M117, M119, M113, M273, M278

Mercedes SL V8 Engines — from £1,500 to £6,500· Common codes: M117, M119, M113, M273, M278

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Mercedes SL500 / SL550 / SL560 — Which Engine Does Your Car Actually Have?

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

Era Note

227 PS — SOHC 2‑valve V8, legendary durability, timing chain guides are the main concern

GenerationYearsEngine CodeReliabilityRecon CostEra Note

R107 (560SL) BMW 320d R107 (560SL)

1986–1989M117.968 (5.6L V8)★★★★½☆ [NEWLY ASSIGNED — see Data Note]£2,500–£4,500 [PLACEHOLDER — confirm vs cost sheet]227 PS — SOHC 2‑valve V8, legendary durability, timing chain guides are the main concern

R129 (SL500) BMW 320d R129 (SL500)

1990–1998M119.972 (5.0L V8)★★★★☆ [NEWLY ASSIGNED — see Data Note]£2,800–£4,800 [PLACEHOLDER — confirm vs cost sheet]326 PS — DOHC 4‑valve V8, distributor caps and wiring harnesses are the Achilles heel

R129 / R230 (SL500) BMW 320d R129 / R230 (SL500)

1998–2006M113.963 (5.0L V8)★★★★☆ [NEWLY ASSIGNED — see Data Note]£2,500–£4,500 [PLACEHOLDER — confirm vs cost sheet]306 PS — SOHC 3‑valve V8, SOHC 3‑valve V8, sludge from short trips and timing chain guide wear are the main issues

R230 Facelift (SL500/SL550) BMW 320d R230 Facelift (SL500/SL550)

2006–2011M273.965 (5.5L V8)★★★☆☆ [NEWLY ASSIGNED — see Data Note]£3,200–£5,500 [PLACEHOLDER — confirm vs cost sheet]388 PS — DOHC 4‑valve V8, timing chain idler sprocket failure is the defining weakness

R231 (SL550) BMW 320d R231 (SL550)

2012–2020M278.928 (4.7L V8 Bi‑Turbo)★★★½☆ [NEWLY ASSIGNED — see Data Note]£4,000–£6,500 [PLACEHOLDER — confirm vs cost sheet]435‑449 PS — twin‑turbo V8, more complex but refined, oil leaks and turbo issues are the main concerns

Why use this era map?

This table is the single source every other section on this page must match. Sections 2, 4, and 6 reference it rather than restating conflicting figures.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Mercedes SL500 / SL550 / SL560 Engine Replacement Costs

Supply Only£2,500–£4,800

Fitted (Indie)£3,800–£6,500

Warranty12–24 months

Best ForMost owners — best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£1,500–£3,000£2,500–£4,5001–6 monthsBudget priority; short‑term ownership

Reconditioned Engine£2,500–£4,800£3,800–£6,50012–24 monthsMost owners — best cost/warranty balance

Rebuilt Engine£3,800–£6,500£5,000–£8,50012–24 monthsLong‑term ownership; maximum reliability

Main Dealer NewN/A (NLA for older engines)N/AN/AM117/M119/M113 no longer available new; M273/M278 limited availability

Figures above reflect the SL V8 pricing across generations. A reconditioned SL V8 engine typically costs £2,500–£4,800 supply only depending on engine generation. On average, a full engine replacement can run anywhere between £3,000 and £8,500 depending on the car model and engine type. The M278 is at the upper end of the range. Mercedes-Benz SL replacement engines are available through specialist suppliers with 12‑month warranties.

Labour estimate: Fitting an SL V8 engine typically takes 12‑18 hours at £75‑£110/hr (independent Mercedes specialist). The SL's low‑slung bonnet and complex engine bay packaging add significant labour complexity, especially for the R230 with its retractable hardtop and ABC suspension.

→ Compare SL V8 engine prices from UK specialists

Common Problems

1. M113 Sludge & Carbon Build‑up (R129/R230 SL500, 1998–2006)

Symptoms: Increased oil consumption, blow‑by, rough idle, tapping noise on start‑up, oil sludge contamination. Carbon build‑up around piston oil control rings in high‑mileage M113 engines is the main reason for increased blow‑by, oil consumption, and oil sludge.

Typical mileage: 60,000–120,000 miles.

Repair cost: £800–£2,500 [PLACEHOLDER] (engine flush, oil control ring cleaning, or cylinder head overhaul).

Replacement cost: N/A — repair only (if caught early; ignored sludge can cause catastrophic engine failure).

🟠 Check - book inspection urgently if you notice tapping noises, oil consumption, or sludge.

Our recommendation:

The M113 engine doesn't like short trips — it needs to get hot to burn off moisture and prevent sludge. A gooey black sludge can build up on internal parts and oil ways. Using the wrong oil or deferred maintenance will accelerate this issue. Regular oil changes (every 8,000‑10,000 miles) using the correct MB‑spec oil are essential. If you hear tapping on start‑up, have the engine inspected immediately.

1. M113 Sludge & Carbon Build‑up (R129/R230 SL500, 1998–2006)

Typical mileage: 60,000–120,000 miles.

Repair cost: £800–£2,500 [PLACEHOLDER] (engine flush, oil control ring cleaning, or cylinder head overhaul).

Replacement cost: N/A — repair only (if caught early; ignored sludge can cause catastrophic engine failure).

🟠 Check - book inspection urgently if you notice tapping noises, oil consumption, or sludge.

Our recommendation:

2. M119 Distributor Cap & Wiring Harness Issues (R129 SL500, 1990–1998)

Symptoms: Rough idle, misfiring, surging, stalling at idle, hesitation on acceleration, engine dying when coming to a stop. The distributor caps and ignition leads are the Achilles heel of the M119.

Typical mileage: 60,000–100,000 miles (age‑related).

Repair cost: £400–£1,200 [PLACEHOLDER] (distributor cap and rotor replacement, ignition leads, wiring harness inspection).

Replacement cost: N/A — repair only.

🟠 Check - book inspection urgently if rough running or stalling occurs.

Our recommendation:

The M119's distributor caps are a known weak point. Moisture and dirt can cause misfires and stalling. The lower and upper engine wiring harnesses can also degrade — if they are still the originals, they will eventually fail. If you experience rough running or stalling, have the ignition system and wiring harnesses inspected.

3. M273 Timing Chain Idler Sprocket Failure (R230 SL500/SL550, 2006–2011)

Symptoms: Engine warning light with timing codes, rattling noise from the front of the engine, rough running, loss of power, potential catastrophic engine failure. The M273 V8 is susceptible to timing chain idler sprocket failure (often referred to as "balance shaft" failure).

Typical mileage: 60,000–120,000 miles.

Repair cost: £2,000–£4,000 [PLACEHOLDER] (timing chain idler sprocket and timing components replacement — engine‑out job).

Replacement cost: £3,200–£5,500 [PLACEHOLDER] (if failure causes catastrophic engine damage).

🔴 Immediate - if the engine warning light appears with timing codes or you hear rattling, book an inspection immediately.

Our recommendation:

The M273's timing chain idler sprocket is the defining weakness of this engine. Mercedes manufactured the idler gear with softer metal than required, leading to premature wear. The M272 V6 and M273 V8 both utilise an idler gear that powers camshaft timing. Engines with serial numbers in certain ranges are affected. Check your engine serial number — later engines (serial numbers above approximately 80,000) are generally safe. If you see timing codes or hear rattling, have the timing system inspected immediately.

4. M273 Oil Separator & Cam Plug Leaks (R230 SL500/SL550, 2006–2011)

Symptoms: Oil spots under the vehicle, burning oil smell, low oil level warning, visible oil leak from the rear of the engine. The oil separator is a common area for oil leaks on the M273 engine.

Typical mileage: 50,000–80,000 miles.

Repair cost: £300–£800 [PLACEHOLDER] (oil separator replacement, cam plug seals).

Replacement cost: N/A — repair only.

🟠 Check - book inspection urgently if oil leak is detected.

Our recommendation:

The M273's oil separator and cam plugs are known leak points. If you notice oil spots or a burning smell, have the oil separator and cam plugs inspected. Replacement is relatively straightforward and much cheaper than letting the leak worsen.

5. M117 Timing Chain Guides (R107 560SL, 1986–1989)

Symptoms: Rattling noise from the front of the engine on cold start, metallic ticking, engine warning light. The timing chain guides are made of plastic that can become brittle and break with age.

Typical mileage: 80,000–150,000 miles.

Repair cost: £800–£2,000 [PLACEHOLDER] (timing chain guides, tensioner, and chain replacement).

Replacement cost: £2,500–£4,500 [PLACEHOLDER] (if chain snaps and damages the engine).

🔴 Immediate - if you hear rattling, book an inspection immediately.

Our recommendation:

The M117's timing chain guides are a known wear item. While the M117 is a robust engine capable of high mileage, the plastic guides can become brittle with age. If the chain breaks, it can cause catastrophic engine damage. A preventative chain and guide replacement is far cheaper than a full engine replacement. Regular oil changes are essential to prolong chain life. As one owner noted: "they all need prompt chain and guide maintenance, frequent oil changes, and hate being overheated".

6. M278 Oil Leaks & Turbocharger Issues (R231 SL550, 2012–2020)

Symptoms: Oil spots under the vehicle, burning oil smell, loss of power, turbo lag, whistling or grinding noise from the engine bay. The M278 is known for oil leaks from the oil cooler and turbocharger oil feed lines.

Typical mileage: 40,000–80,000 miles.

Repair cost: £800–£2,500 [PLACEHOLDER] (oil cooler seal replacement, turbo oil line replacement).

Replacement cost: N/A — repair only.

🟠 Check - book inspection urgently if oil leak is detected or power loss occurs.

Our recommendation:

The M278 4.7L bi‑turbo V8 is a sophisticated engine, but the turbocharger oil feed lines and oil cooler seals can develop leaks. If you notice oil spots or a burning smell, have the engine inspected immediately. Regular oil changes using the correct MB‑spec oil are essential to prolong turbo life.

Weighing Your Options?

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Mercedes SL V8 — 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.

Mercedes SL V8 — 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 SenseM113 sludge / carbon build‑up✅ Yes£800–£2,500 [PLACEHOLDER]Worth fixing — common on high‑mileage M113sM119 distributor & wiring issues✅ Yes£400–£1,200 [PLACEHOLDER]Worth fixing — common and well‑understood repairM273 timing chain idler sprocket wear✅ Yes (if caught early)£2,000–£4,000 [PLACEHOLDER]Catch it early — engine‑out job but cheaper than replacementM273 timing chain idler failed❌ Usually No£3,200–£5,500+Full engine replacement often more cost‑effectiveM117 timing chain guide wear✅ Yes (if caught early)£800–£2,000 [PLACEHOLDER]Catch it early — cheaper than engine replacementM117 timing chain snapped❌ Usually No£2,500–£4,500+Full engine replacement — valvetrain damage is likelyM273/M278 oil leaks✅ Yes£300–£800 [PLACEHOLDER]Essential maintenance — always worth doingMajor internal failure (any engine)❌ Usually No£2,500–£6,500+Full engine replacement often more cost‑effective

Buying This Mercedes SL V8? Check These First

Buy If

Full Mercedes service history with regular oil changes (every 8,000‑10,000 miles)
R107 (M117): Timing chain guides replaced — this is critical on higher‑mileage cars
R129 early (M119): Distributor caps and wiring harnesses replaced
R129 late / R230 early (M113): No sludge, regular oil changes, good maintenance history
R230 facelift (M273): Engine serial number above 80,000 — idler sprocket issue resolved
R231 (M278): No oil leaks, turbo system in good health

Avoid If

R107 (M117): Any sign of timing chain rattle on cold start — guide warning
R129 early (M119): Any sign of rough idle or stalling — distributor or wiring warning
R129 late / R230 early (M113): Any sign of sludge or tapping — oil system warning
R230 facelift (M273): Any sign of rattling or timing codes — idler sprocket warning
R231 (M278): Any sign of oil leaks — turbo or oil cooler warning
Poor service history — these engines are intolerant of neglect

Closing Verdict

The Mercedes SL500, SL550 and SL560 represent some of the most iconic V8‑powered roadsters ever built. The M117 in the R107 560SL is a legendary engine with near‑mythical durability. The M119 in the early R129 is a DOHC masterpiece with a sensitive ignition system. The M113 in the late R129 and early R230 is a robust SOHC V8 that doesn't like short trips. The M273 in the facelift R230 is a powerful DOHC V8 with a well‑documented timing chain idler sprocket vulnerability. The M278 in the R231 is a sophisticated twin‑turbo V8 with oil leak and turbo concerns. Buy on service history and engine serial number above all else — a well‑maintained SL V8 is a rewarding and collectable car; a neglected example can be expensive to repair. As one specialist noted, the M113 "doesn't like short journeys" and "no amount of oil changes will stave off piston ring damage and cylinder wall scoring".

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

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Buying Checklist

Before you buy a used Mercedes SL V8 (or before you commit to an engine replacement), check these:

1. Cold Start — Any rattling? (M117/M273 timing chain warning — stop immediately)

2. Service History — Regular oil changes (every 8,000‑10,000 miles) — this is non‑negotiable

3. Engine Serial Number — M273: Check if above 80,000 (idler sprocket issue resolved)

4. Engine Warning Light — Have codes been read? Any timing codes? (M273 warning)

5. Oil Leaks — Check under the vehicle and around the engine for any signs of leakage

6. Running Quality — Any rough idle, stalling, or hesitation? (M119 distributor or M113 sludge warning)

7. Oil Consumption — Does it use more than 1L per 1,000 miles? (M113 sludge warning)

8. MOT History — Check for emissions‑related failures or any advisory notes

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.

M117.968 (5.6L V8)

Years1986–1989

Power227 PS (167 kW) / 390 Nm

2025 Enquiries— (pattern data)

Avg. Recon Cost£2,500–£4,500 [PLACEHOLDER]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

M117.968 (5.6L V8)1986–1989227 PS (167 kW) / 390 Nm— (pattern data)£2,500–£4,500 [PLACEHOLDER]

M119.972 (5.0L V8)1990–1998326 PS (240 kW) / 470 Nm— (pattern data)£2,800–£4,800 [PLACEHOLDER]

M113.963 (5.0L V8)1998–2006306 PS (225 kW) / 460 Nm— (pattern data)£2,500–£4,500 [PLACEHOLDER]

M273.965 (5.5L V8)2006–2011388 PS (285 kW) / 530 Nm— (pattern data)£3,200–£5,500 [PLACEHOLDER]

M278.928 (4.7L V8 Bi‑Turbo)2012–2020435‑449 PS (320‑330 kW) / 700 Nm— (pattern data)£4,000–£6,500 [PLACEHOLDER]

Technical Specs

M278.928 — 4.7L Bi‑Turbo V8

Displacement5,547 cc

Cylinders8‑cylinder V8

ValvetrainSOHC, 2 valves per cylinder

Block MaterialCast iron

Fuel SystemMechanical fuel injection

Displacement4,973 cc

Cylinders8‑cylinder V8

Bore x Stroke96.5 x 85.0 mm

ValvetrainDOHC, 4 valves per cylinder

Block MaterialAluminium

Fuel SystemElectronic fuel injection

Displacement4,966 cc

Cylinders8‑cylinder V8 (90° V)

Bore x Stroke97.0 x 84.0 mm

Compression Ratio10.0:1

ValvetrainSOHC, 3 valves per cylinder

Block MaterialLight‑alloy block

Fuel SystemManifold injection

Displacement5,461 cc

Cylinders8‑cylinder V8

Bore x Stroke98.0 x 90.5 mm

ValvetrainDOHC, 4 valves per cylinder

Block MaterialAluminium

Fuel SystemSequential port fuel injection

Displacement4,663 cc

Cylinders8‑cylinder V8

ValvetrainDOHC, 4 valves per cylinder

Block MaterialAluminium

Fuel SystemDirect injection

AspirationBi‑Turbocharged

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Market Intelligence

Most Common Failure

M273: Timing chain idler sprocket failure — M113: Sludge/carbon build‑up — M119: Distributor/wiring issues

Average Enquiry Mileage

50,000

–80,000 miles

[PATTERN DATA]

Average Replacement Cost

£3,500

reconditioned, supply only

[PLACEHOLDER]

Most Requested Engine Code

M113 — the SL500 is the most common SL variant

[PATTERN DATA]

Peak Enquiry Season

Spring/Summer — convertible roadster interest peaks

[PATTERN DATA]

Regional Demand

South East22%

London18%

South West (12%) — premium roadster strongholds

PATTERN DATA

Regional Demand Breakdown

22%South East

18%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.

Why UK Mercedes SL V8 Owners Trust MercedesEngine.uk

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every garage and engine rebuilder in our network is vetted, rated and reviewed by real SL owners, as part of the Engine Finders network, covering the legendary M117, M119, M113, M273 and M278 V8 engines across four generations of the iconic roadster.
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see prices, warranty terms and supply & fit options side‑by‑side before you commit, with specialists who understand the M117's timing chain guide requirements, the M119's distributor vulnerabilities, the M113's sludge issues, the M273's idler sprocket weaknesses, the M278's oil leak and turbo concerns, and the importance of regular oil changes.
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supply‑only or full supply & fit available nationwide, covering the R107, R129, R230 and R231 generations of the SL500, SL550 and SL560, with specialist knowledge of Mercedes' iconic V8 roadster engines.

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