Mercedes‑Benz SL600 / SL65 AMG V12 Engine Replacement — Compare Prices & Get Quotes
Get quotes today from trusted UK Mercedes‑Benz V12 specialists. Compare reconditioned, rebuilt and used 6.0‑litre and 5.5‑litre V12 engines — M120, M137 and M275 variants across the R129 and R230 generations — supply & fit available nationwide.
The SL600 / SL65 AMG V12 THROUGH TIME — Era Map
Four generations. Four eras. One guide to reliability, costs and what really matters.
Era Note
6.0L NA V12 — 389‑394 hp, 420 lb‑ft; bulletproof mechanically; biodegradable wiring harness (1992‑95) and coil packs are the main watch items
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 SL600 / SL65 AMG V12 Engine Replacement Costs
Figures above reflect current SL600 / SL65 AMG replacement costs. The M275 AMG 6.0L variant typically sits at the higher end of the range. See the Era Map above for generation‑specific pricing.
Labour estimate: Fitting an SL600 / SL65 AMG engine typically takes 14–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). Engine bay access is notoriously tight on the R230, increasing labour times.
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SL600 / SL65 AMG V12 — 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 SL600 / SL65 AMG V12? Check These First
Buy If
- R129 (1992‑1997) with M120 — bulletproof mechanically, wiring harness replaced
- R230 (2003‑2012) with M275 and recent coil pack replacement (both banks)
- Full Mercedes service history with regular oil changes (critical for V12 longevity)
- No misfires or rough running (coil pack health)
- No oil leaks around valve covers or turbos (seal health)
- No cold‑start rattling (timing chain health)
- Post‑2003 with the twin‑turbo M275 — the most powerful and refined SL V12
Avoid If
- R230 (1999‑2001) with M137 — notoriously unreliable, cylinder wall wear issues
- M275 with misfires and no coil pack history — budget for coil pack replacement immediately
- M275 with oil leaks — valve cover gaskets or turbo seals may be failing
- Cold‑start rattling and no timing chain history — budget for chain work
- No service history — V12s are unforgiving of neglect
- Any history of engine failure or major repairs without documentation
Closing Verdict
The SL600 and SL65 AMG V12 represent the pinnacle of Mercedes‑Benz open‑top motoring — a handcrafted twelve‑cylinder experience that defines the brand's flagship roadster. The M120 (R129, 1992‑1997) is widely considered bulletproof mechanically, making it the most reliable of the three V12 generations — a genuine future classic. The M137 (R230, 1999‑2001) was short‑lived and has a reputation for being notoriously unreliable — best avoided. The M275 (R230, 2003‑2012) delivers breathtaking twin‑turbo performance — 493‑603 hp and up to 738 lb‑ft torque — but demands careful ownership. Common issues include coil pack failure (£1,000 per pack), oil leaks from valve cover gaskets and turbo seals, and timing chain stretch. The M275 AMG 6.0‑litre in the SL65 is one of Affalterbach's most legendary creations. With typical SL values ranging from £15,000 (R129) to £50,000+ (R230 SL65), an engine replacement is a major financial commitment — a well‑maintained M120 R129 or a post‑2003 M275 SL65 with documented coil pack and maintenance history is the safest choice. The M137 is best avoided entirely.
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Buying Checklist
Before you buy a used Mercedes‑Benz SL600 / SL65 AMG V12 (or before you commit to an engine replacement), check these:
Coil Packs — Check for smooth idle; any misfires may indicate coil pack failure (M275) — see the map above
Cold Start — Listen for rattling or clattering (timing chain warning — M275)
Oil Leaks — Check around valve covers and turbo areas for leaks (M275)
Wiring Harness — For R129 (1992‑1995): check if biodegradable wiring harness has been replaced (M120)
Service History — Including which engine era (M120, M137 or M275) and oil‑change discipline
Engine Warning Light — Have codes read; unresolved issues may indicate coil, timing, oil or sensor problems
Transmission — Check 5G‑Tronic operation; early M275 produced too much torque for the gearbox
ABC Suspension — R230 ABC suspension is a major maintenance item — check for leaks and function
MOT History — Check for emissions‑related failures
Roof Operation — R230 folding hardtop mechanism is complex and expensive to repair
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.
M120.981 (6.0L NA V12)
Technical Specs
M120.981 — R129 SL600→ Compare SL600 / SL65 AMG V12 engine prices for your SL
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Market Intelligence
Most Common Failure (M275)
Coil pack failure — the most frequent SL600 / SL65 AMG engine enquiry
Most Common Failure (M120)
Biodegradable wiring harness (1992‑1995) — the defining issue of the early R129
Average Enquiry Mileage
40,000
–70,000 miles
[PATTERN DATA]
Average Replacement Cost
£7,000
–£10,000 reconditioned, supply only
[PLACEHOLDER]
Most Requested Engine Code
M275.981 / M275.950
[PATTERN DATA]
Peak Enquiry Season
Year‑round — V12 maintenance is a constant consideration
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 SL600 / SL65 AMG V12 Owners Trust MercedesEngine.uk
Trusted SL V12 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real SL600 and SL65 AMG owners, as part of the Engine Finders network, across every engine era — M120, M137 and M275 — covering the R129 and R230 generations.
Compare SL V12 Engine Replacement Companies
see prices, warranty terms and supply & fit options side‑by‑side before you commit. We cover the 6.0L and 5.5L V12 engines specifically, with specialists who understand the M275 coil pack vulnerabilities, oil leak issues, timing chain concerns, and the unique requirements of the SL.
UK Engine Replacement Services for SL V12
supply‑only or full supply & fit available nationwide, covering every generation of this badge since 1992, with a 12‑month warranty as standard across our network.
Find the best Mercedes‑Benz SL600 / SL65 AMG V12 engine replacement UK owners rely on. Compare prices from trusted specialists on EnginesMarket today and keep your V12 roadster 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