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Mercedes SL55/63 AMG SPECIALISTS

Mercedes Benz SL Class SL55/SL63 AMG Engine Replacement Compare Prices & Get Quotes

Get quotes today from trusted UK Mercedes Benz SL Class SL55 AMG and SL63 AMG engine specialists. Compare prices on reconditioned, rebuilt and used engines for the hand-built supercharged V8 and naturally aspirated V8 - supply & fit available nationwide.

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Mercedes Benz SL Class SL55/SL63 AMG Engine
from£4,500 to £10,00...
  • Usedfrom £2,500
  • Reconditionedfrom £4,500
  • Common codesM113.991, M156.981, M156.982
Mercedes Benz sl Class SL55/SL63 AMG Used Engine — M113KMercedes Benz slUsed Engine — M113KMercedes Benz sl Class SL55/SL63 AMG Reconditioned Engine — M113KMercedes Benz slReconditioned Engine — M113KMercedes Benz sl Class SL55/SL63 AMG Rebuilt Engine — M113KMercedes Benz slRebuilt Engine — M113K

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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 SL Class SL55/SL63 AMG Engine History & Specs at a Glance

The SL55 AMG and SL63 AMG represent two distinct eras of AMG engineering excellence. The SL55 AMG launched in 2003 with the M113K 5.4-litre supercharged V8 - a hand-built engine producing 493hp and 516 lb-ft of torque. In 2008, the SL63 AMG replaced it with the M156 6.2-litre naturally aspirated V8, producing 518hp and 465 lb-ft of torque. The M113K delivered relentless, supercharged torque that defined the early 2000s AMG experience, while the M156 brought high-revving naturally aspirated character and an iconic soundtrack. Both engines were hand-built in Affalterbach, representing the pinnacle of AMG V8 engineering.

Mercedes Benz SL Class SL55/SL63 AMG
  1. 2003

    M113K, 5.4L supercharged V8, 493hp @ 6,100rpm, 700Nm torque (SL55 AMG, R230 launch)

  2. 2004

    2008 - M113K continues with P030 Performance Package available from 2004

  3. 2006

    M113K, 5.4L supercharged V8, 510hp @ 6,100rpm (facelift SL55 AMG)

  4. 2008

    M156.981, 6.2L naturally aspirated V8, 518hp @ 6,800rpm, 630Nm torque (SL63 AMG, replaces SL55)

  5. 2009

    2011 - M156.981 continues as the SL63 AMG engine through end of R230 production

Every engine fitted to the Mercedes Benz SL Class SL55 AMG and SL63 AMG is covered below, with UK rebuilt pricing and known failure points - from M113K supercharger coupler wear to M156 head bolt corrosion.

Engine Codes & Pricing

Mercedes Benz SL Class SL55/SL63 AMG Engine Codes Specifications & Replacement Cost

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

M113K — 5.4L Supercharged V8 (2003-2008) engine

M113K — 5.4L Supercharged V8 (2003-2008)

Power Output
493 hp (368 kW) @ 6,100 rpm (early); 510 hp (380 kW) @ 6,100 rpm (facelift with Performance Package)
Torque
700 Nm (516 lb-ft) @ 2,600-4,000 rpm
Years Fitted
2003-2008
Displacement
5,439 cc (5.4L)
Cylinders
V8, 90° V-angle, SOHC, 24-valve (3 valves per cylinder)
Engine Code
M 113.991 (M113K Kompressor)

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Common Problems

Mercedes Benz SL Class SL55/SL63 AMG Engine Problems Repair Cost vs Replacement

The SL55's M113K supercharged V8 and the SL63's M156 naturally aspirated V8 are among AMG's most celebrated engines - hand-built masterpieces from Affalterbach. However, both have well-documented weaknesses that can lead to significant repair costs. The M113K suffers from supercharger coupler and bearing wear, while the M156 is notorious for head bolt corrosion. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing these original failure points, plus a minimum 12-month unlimited-mileage warranty.

Common failure points and repair options

M113K Supercharger Coupler & Bearing Wear

Affected
Mercedes SL55 AMG (M113K, 2003-2008)
Typical failure mileage
60,000-90,000 miles
Root cause
The M113K's supercharger relies on a clutch and bearings to function properly. Over time, these components can wear out, leading to unusual noises, reduced power delivery, and even supercharger failure. The supercharger rear bearings are reportedly unserviceable according to some sources. Merc sees the supercharger as a single replacement unit and offers nothing separately.

Repair options

Repair tierDealer priceSpecialist price
Diagnostics - Supercharger inspection£200-£400£150-£300
Intermediate - Supercharger rebuild£2,500-£4,000£1,600-£2,500
Major - Supercharger replacement£4,000-£6,500£2,800-£4,500
Full Replacement - Rebuilt M113K engine£9,000-£12,000£5,500-£8,500
Our recommendation
M113K supercharger wear is progressive. If you hear unusual noises from the supercharger or notice reduced power, have it inspected immediately. Specialist supercharger rebuild at £1,600-£2,500 is significantly cheaper than dealer rates. If the supercharger has failed catastrophically, a full rebuilt M113K engine with a new supercharger is the only safe option.
-> Compare rebuilt M113K Mercedes SL55 AMG engine prices

M156 Head Bolt Corrosion

Affected
Mercedes SL63 AMG (M156.981, 2008-2011)
Typical failure mileage
20,000-80,000 miles
Root cause
The M156 engine is notorious for head bolt failure on 2007-2011 production engines. The original bolts had a defect in the anti-corrosive coating and a weaker hollow torx bolt head design. Failure causes coolant to leak into the cylinders, triggering "Top up coolant" warnings. If ignored, coolant ingress can cause hydrolock, bending connecting rods and destroying the engine. Engines with numbers below 60,060,658 are affected.

Repair options

Repair tierDealer priceSpecialist price
Diagnostics - Head bolt inspection£300-£500£200-£350
Preventative - Head bolt replacement£4,000-£6,000£2,500-£4,000
Major - Cylinder head & bolt replacement£6,000-£8,500£4,000-£6,000
Full Replacement - Rebuilt M156 engine£10,000-£14,000£6,500-£10,000
Our recommendation
If your SL63 AMG's M156 engine number falls below 60,060,658, we strongly recommend preventative head bolt replacement. The upgraded ARP studs or OEM updated bolts permanently resolve the corrosion issue. If you experience any "Top up coolant" warnings or coolant loss, do not drive the vehicle - coolant in the cylinders can cause hydrolock and catastrophic engine failure. Specialist head bolt replacement at £2,500-£4,000 is significantly cheaper than dealer rates. On an SL63 AMG worth £15,000-£35,000, this is a worthwhile investment to preserve the vehicle's value and reliability.
-> Compare rebuilt M156 Mercedes SL63 AMG engine prices

M113K Oil Leaks & Ignition Issues

Affected
Mercedes SL55 AMG (M113K, 2003-2008)
Typical failure mileage
60,000-100,000 miles
Root cause
The M113K shares the common M113 family oil leak issues. Valve cover gaskets become hard and brittle with age and heat cycling. Ignition system issues including worn spark plugs and failing ignition coils can cause misfires and rough running. Harmonic balancer failure (rubber element separating from metal) is also reported.

Repair options

Repair tierDealer priceSpecialist price
Minor - Valve cover gasket replacement£600-£1,000£400-£700
Intermediate - Ignition system overhaul£800-£1,500£500-£1,000
Major - Harmonic balancer replacement£800-£1,200£500-£900
Full Replacement - Rebuilt M113K engine£9,000-£12,000£5,500-£8,500
Our recommendation
Oil leaks on the M113K are common with age but not usually urgent unless they are heavy. Valve cover gasket replacement at a specialist is significantly cheaper than dealer rates. If you experience misfires, have the ignition system inspected immediately. Use only OEM Mercedes-Benz gaskets and genuine ignition components.
-> Compare rebuilt M113K Mercedes SL55 AMG engine prices

M156 Camshaft Adjuster & Oil Leak Issues

Affected
Mercedes SL63 AMG (M156.981, 2008-2011)
Typical failure mileage
60,000-100,000 miles
Root cause
The M156 engine can suffer from camshaft adjuster magnet failure, causing timing faults and rough running. Oil leaks from valve cover gaskets, camshaft solenoid cover gaskets, and oil filter housing gaskets are also common. Sticking or leaking fuel injectors are a critical issue, with replacement recommended around 60,000 miles.

Repair options

Repair tierDealer priceSpecialist price
Minor - Camshaft adjuster magnet replacement£800-£1,500£500-£900
Intermediate - Oil leak repair£1,000-£1,800£700-£1,200
Major - Fuel injector replacement£1,500-£2,500£1,000-£1,800
Full Replacement - Rebuilt M156 engine£10,000-£14,000£6,500-£10,000
Our recommendation
Camshaft adjuster magnet failure on the M156 is a known issue. If you experience rough running or timing faults, have the camshaft adjusters inspected immediately. Fuel injector replacement at 60,000 miles is recommended as preventative maintenance - a stuck-open injector can hydrolock the engine.
-> Compare rebuilt M156 Mercedes SL63 AMG engine prices

Don't Let Supercharger Wear, Head Bolt Corrosion, or Oil Leaks Write Off Your Mercedes SL55 or SL63 AMG

Whether you're facing M113K supercharger coupler wear on your SL55 AMG or M156 head bolt corrosion on your SL63 AMG, EnginesMarket makes it simple to compare quotes from trusted UK Mercedes AMG specialists. Every rebuilt engine in our network carries upgraded components addressing the original design weakness - rebuilt superchargers with new bearings, ARP head studs, and fresh gaskets and seals - plus a minimum 12-month unlimited mileage warranty with nationwide delivery and supply & fit options. Don't pay main dealer premiums. Compare prices from independent AMG specialists who know these hand-built V8 engines inside out.

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FAQ

Mercedes Benz SL Class SL55/SL63 AMG Engine ReplacementFrequently Asked Questions

Everything Mercedes Benz SL Class SL55/SL63 AMG owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

Why Choose Us

Compare Mercedes SL Class SL55/SL63 AMG Engine Prices Today

Comparing quotes for your Mercedes SL55 or SL63 AMG is completely free, with no obligation and no pressure. Enter your registration above to get tailored quotes from UK Mercedes AMG specialists who understand the M113K supercharged V8 and the M156 naturally aspirated V8 inside out. Whether you need a used engine, a reconditioned unit, or a full rebuilt engine with upgraded supercharger components, ARP head studs, and fresh gaskets, we'll connect you with the right specialist for your exact SL - with a minimum 12-month warranty on every engine supplied.

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