How much does a Mercedes‑Benz SL55 / SL63 AMG engine replacement cost in the UK?

A reconditioned M113K engine typically costs £4,000–£8,000 supply only; the M157 costs £6,000–£16,000. Fitting adds £1,000–£1,800. Main dealer new engines can exceed £30,000. M157 replacement motors average £14,167. Use our calculator for a figure specific to your car.

Is the Mercedes‑Benz SL55 / SL63 AMG engine reliable?

It depends on the engine. The M113K (SL55) is rated ★★★★☆ — widely considered bulletproof with 'galactic miles' reported by owners. The M157 (SL63) is rated ★★★☆☆ — early examples (2010–2014) have timing chain, oil leak, and cylinder scoring risks. Post‑2014 M157s are more reliable.

What are the common problems with the Mercedes‑Benz SL55 / SL63 AMG?

M113K issues: supercharger coolant pump failure, valve cover oil leaks, AMG‑specific idler pulley wear, and the plastic selector peg in the five‑speed gearbox. M157 issues: timing chain wear (early cars), camshaft position sensor oil leaks, valve cover gasket leaks, cylinder scoring, and coolant system leaks.

Is it worth replacing a Mercedes‑Benz SL55 / SL63 AMG engine, or should I scrap the car?

Depends on vehicle value. Against a well‑kept SL55 AMG worth £15,000–£25,000, a £4,000–£8,000 recon is a manageable 16–53% of the vehicle's value — worth it for a well‑maintained example. For a SL63 AMG worth £20,000–£40,000, a £6,000–£16,000 recon is more significant but often worthwhile given the SL's status and strong retained values.

How do I find my Mercedes‑Benz SL55 / SL63 AMG engine code?

Listed on the VIN plate and vehicle documentation. The SL55 AMG uses the M113K (M113.991) 5.4‑litre supercharged V8. The SL63 AMG uses the M157 (157.983) 5.5‑litre twin‑turbo V8. Tell us your registration date and we'll confirm it for free.

Can I repair the M157's timing chain, or does it need a new engine?

Yes — if caught early. A timing chain, tensioner and guide replacement (£1,500–£4,000) is far cheaper than a catastrophic chain failure (£6,000–£16,000 engine replacement). Install the updated chain tensioner and non-return valves. At the first sign of cold‑start rattle, book an inspection immediately. Early M157s (2010–2012) are most affected.

Mercedes-Benz SL55 / SL63 AMG2003–20202 Engine Generations

Mercedes-Benz SL55 / SL63 AMG Engine Replacement — Compare Prices & Get Quotes

Get quotes today from trusted UK Mercedes-Benz AMG specialists. Compare reconditioned, rebuilt and used M113K and M157 engines — supply & fit available nationwide.

Supply & Fit Available

12‑Month Warranty

Nationwide Delivery

25+ Specialists

Supply & Fit Available

12‑Month Warranty

Nationwide Delivery

25+ Specialists

Mercedes SL55 / SL63 AMG Engines — from £4,000 to £16,000Common codes: M113K, M157

Mercedes SL55 / SL63 AMG Engines — from £4,000 to £16,000· Common codes: M113K, M157

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK‑Wide Network

The SL55 / SL63 AMG THROUGH TIME — Era Map

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

Era Note

The supercharged M113K — 493 bhp, bulletproof when maintained; valve cover seals, oil leaks and supercharger coolant pump are the main watchpoints.

GenerationYearsEngine CodeReliabilityRecon CostEra Note

R230 (SL55 AMG) BMW 320d R230 (SL55 AMG)

2003–2011M113K (5.4 Supercharged V8)★★★★☆ [NEWLY ASSIGNED — see Data Note]£4,000–£8,000 [MB‑QUOTE]The supercharged M113K — 493 bhp, bulletproof when maintained; valve cover seals, oil leaks and supercharger coolant pump are the main watchpoints.

R231 (SL63 AMG) BMW 320d R231 (SL63 AMG)

2012–2020M157 (5.5 BiTurbo V8)★★★☆☆ [NEWLY ASSIGNED — see Data Note]£6,000–£16,000 [MB‑QUOTE]The twin‑turbo M157 — 536–577 bhp; timing chain wear, oil leaks and cylinder scoring are the defining weaknesses.

Why use this era map?

Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Mercedes-Benz SL55 / SL63 AMG Engine Replacement Costs

Supply Only£5,000–£10,000

Fitted (Indie)£6,100–£11,500

Warranty12–24 months

Best ForMost owners — best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£4,000–£7,500£5,000–£8,8003–6 monthsBudget priority; vehicle under £15,000

Reconditioned Engine£5,000–£10,000£6,100–£11,50012–24 monthsMost owners — best cost/warranty balance

Rebuilt Engine£8,000–£16,000£9,200–£17,50012–24 monthsLong‑term ownership; 3+ year horizon

Main Dealer New£20,000–£30,000+£22,000–£33,000+24–36 monthsInsurance jobs, warranty claims; M157 replacement motors average £14,167+

Labour estimate: Fitting an SL AMG engine typically takes 14–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). AMG-specific parts are significantly more expensive than standard Mercedes components — an idler pulley for the AMG is £350 vs £50 for the standard version.

Common Problems

Weighing Your Options?

Compare Specialist Quotes When You're Ready

25+ vetted Mercedes‑Benz AMG specialists, every SL55 / SL63 AMG variant covered, with a 12‑month warranty as standard.

See SL AMG Engine Options

Mercedes-Benz SL55 / SL63 AMG — 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-Benz SL55 / SL63 AMG — 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 SenseM113K supercharger coolant pump failure✅ Yes£300–£800Straightforward pump replacement; catch it before performance lossM113K valve cover seal leaks✅ Yes£300–£800Replace seals; catch it before low oil levelsM113K idler pulley wear✅ Yes£350+Replace with AMG-specific part; don't let it failM157 timing chain wear (early)✅ Yes£1,500–£4,000If caught early; update tensioner and non-return valvesM157 cam position sensor oil leaks✅ Yes£300–£800Preventative — catch it before oil reaches the ECUM157 cylinder scoring⚠️ Depends£5,000–£10,000+Bore scoring is serious; sleeve and rebuild requiredFive-speed gearbox selector peg (R230)✅ Yes£200–£500Replace with aluminium peg; dealer may replace entire unit

Buying This SL55 / SL63 AMG? Check These First

Buy If

Full Mercedes service history with documented oil changes
SL55 M113K — widely considered bulletproof
SL63 M157 post‑2014 (timing chain issues resolved)
SL63 M157 with documented timing chain tensioner update
Evidence of charge cooler pump replacement (M113K) or cam sensor seals (M157)

Avoid If

M157 with cold‑start rattle and no timing chain history — the single most important check on the SL63
Oil in camshaft sensor connectors — potential ECU damage risk
Any evidence of cylinder scoring (misfires, loss of compression)
Poor service history — AMG engines are unforgiving of neglect

Closing Verdict

The SL55 AMG's M113K is widely considered one of Mercedes' most bulletproof performance engines — a supercharged V8 masterpiece with "galactic miles" reported by owners. The SL63 AMG's M157 is a more complex twin-turbo engine with known timing chain, oil leak, and cylinder scoring risks — particularly on early examples. The M113K is the more reliable choice; the M157 offers more power but demands diligent maintenance. Buy on documented history. If you're replacing, a reconditioned unit with a 12‑month warranty is the sweet spot.

20+ Vetted Specialists UK Network

12-Month Warranty as Standard

Nationwide Delivery & Collection

Transparent Pricing, No Hidden Fees

Thousands of 320d Owners Helped

Buying Checklist

Before you buy a used Mercedes‑Benz SL55 / SL63 AMG (or before you commit to an engine replacement), check these:

Model & Engine — Confirm which engine the car has (M113K for SL55 AMG R230, M157 for SL63 AMG R231)

Cold Start — Listen for rattling noise on startup (M157 timing chain warning — the most critical check)

Service History — Including which engine era (M113K for R230 2003–2011, M157 for R231 2012–2020) — see the Era Map above

Oil Leaks — Check for oil spots under the car or burning oil smell (M113K valve covers, M157 cam sensors)

Cam Sensor Connectors — Disconnect and check for oil — oil in the plug could mean a new ECU (M157)

Supercharger Health — Any loss of power? M113K charge cooler pump failure risk

Idler Pulley — Any squeaking or chirping? AMG-specific part is expensive

Transmission — Any hesitation from Park to Drive? R230 plastic selector peg issue

Engine Warning Light — Have codes been read? Any unresolved timing, boost, or emissions issues?

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

M113K (M113.991)

Years2003–2011

Power493 bhp / 700 Nm

2025 Enquiries— (pattern data)

Avg. Recon Cost£4,000–£8,000 [MB‑QUOTE]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

M113K (M113.991)2003–2011493 bhp / 700 Nm— (pattern data)£4,000–£8,000 [MB‑QUOTE]

M157 (157.983)2012–2020536–577 bhp / 800–900 Nm— (pattern data)£6,000–£16,000 [MB‑QUOTE]

Technical Specs

M157

Displacement5,439cc

Cylinders8‑cylinder V (90°)

Bore × Stroke97.0 × 92.0 mm

Compression Ratio9.0:1

Fuel SystemMulti‑point fuel injection (MPFI)

InductionBelt‑driven screw‑type supercharger

ValvetrainSOHC, 24‑valve, 3 valves per cylinder

Displacement5,461cc

Cylinders8‑cylinder V (90°)

Bore × Stroke98.0 × 90.5 mm

Compression Ratio10.0:1

Fuel SystemDirect injection (piezoceramic injectors)

TurbochargerTwin Garrett MGT2260MSL

ValvetrainDOHC, 32‑valve, with VVT

Market Intelligence

Most Common Failure

M113K charge cooler pump and oil leaks; M157 timing chain wear (early) and cam sensor oil leaks — approximately 55% of SL AMG enquiries

Average Enquiry Mileage

55,000

miles

Average Replacement Cost

£7,500

reconditioned, supply only

[MB‑QUOTE]

Most Requested Engine Code

M157 (SL63)

Peak Enquiry Season

Spring — convertible season exposes cooling and drivability issues

Regional Demand

London25%

South East22%

South West15%

Regional Demand Breakdown

25%London

22%South East

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‑Benz SL55 / SL63 AMG engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and keep your AMG V8 on the road.

Explore Mercedes‑Benz SL55 / SL63 AMG Engine Quotes

100% Free

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

100% Free

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