How much does a Mercedes SLK R170 engine replacement cost in the UK?

A reconditioned R170 engine typically costs £1,500–£7,000 supply only, depending on engine — the M111 four-cylinder Kompressor sits at £1,500–£3,500, while the M112 supercharged V6 in the SLK 32 AMG is the most expensive at £4,000–£7,000. Fitting adds £650–£1,300 depending on engine complexity and specialist rates. Use our calculator for a personalised figure.

What are the common problems with the Mercedes SLK R170?

Supercharger clutch failure and timing chain issues on the M111 Kompressor engines, valve cover gasket leaks and crank position sensor failure on the M112 V6, supercharger clutch wear on the SLK 32 AMG, and vario-roof hydraulic system failures across all variants. The M111's cam magnet oil migration into the wiring loom and ECU is also a well-known issue.

Is the Mercedes SLK R170 reliable?

Overall reliability is good for a late-1990s/early-2000s Mercedes. The M111 Kompressor engines are generally robust but require supercharger clutch and timing system attention around 60,000–100,000 miles. The M112 V6 is the most reliable option. The main caveat is the M111's timing chain and cam magnet oil migration issues — if the wiring loom hasn't been addressed, budget for the modified piggyback loom (around £20). The vario-roof is a common non-engine failure point.

Which Mercedes SLK R170 engine should I avoid?

No engine outright — but the pre-facelift M111.943 and M111.973 Kompressor engines (1996–2000) have more documented issues than their facelift counterparts, including oil migration from the cam magnet into the wiring loom, timing chain issues, and variable timing gear problems. If you're on a budget, the SLK 320 (M112 V6) is the best choice for reliability. Avoid any car without documented timing chain and supercharger service history.

How do I know if my R170 engine needs replacing?

Loss of boost or a rattling noise from the front of the engine (supercharger clutch failure on Kompressor cars), a rattle when revved or engine warning lights (variable timing gear issues), oil in the wiring loom or ECU issues (cam magnet oil migration), persistent coolant loss or overheating (M112/M113 cooling system), or the vario-roof failing to operate correctly are the key warning signs. Use our diagnostic calculator for a personalised assessment.

Is it worth replacing a Mercedes SLK R170 engine, or should I scrap the car?

Depends on the car's value. Against a well-kept £7,000 SLK 320, a £2,500–£4,500 recon is 36–64% of the car's value — borderline but viable. Against a tired £2,500 SLK 200, a £1,500–£2,800 recon is 60–112% — walk away. For an SLK 32 AMG, a £12,000+ car justifies a £4,000–£7,000 recon. Our 70% Mercedes-Benz threshold is the line.

How long do Mercedes SLK R170 engines last?

The M112 V6 can exceed 200,000 miles with regular servicing and prompt cooling system attention. The M111 Kompressor four-cylinders can reach 150,000–200,000 miles with supercharger clutch and timing system attention around 60,000–100,000 miles. The M112.960 AMG V6 is robust but requires supercharger clutch attention at similar intervals.

What is the difference between the R170 and R171 SLK?

The R170 (1996–2004) is the first-generation SLK — the one that pioneered the modern folding metal roof. It features a more classic, rounded design and is built on a shortened W202 platform. The R171 (2004–2011) is the second generation with more aggressive, angular styling and updated engines. Engines are generally not interchangeable between the two generations. See our R171 page for that generation's specifics.

R170 Engine Replacement Cost UK

Mercedes SLK R170 Engine Codes — The Complete Database

Every engine fitted to the R170 roadster specifically — including pre-facelift M111 units, the 2000 facelift updates, the V6-powered SLK 320, and the range-topping AMG.

Engine CodeFamilyFuelDisplacementPowerYears (R170)Variants (badges)Reliability2025 EnquiriesAvg. Recon Cost

M111.946M111Petrol2.0L (1998cc)136 PS / 100 kW1996–2000SLK 200★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,500–£2,800 [PLACEHOLDER — confirm vs cost sheet]

M111.943M111Petrol, supercharged2.0L (1998cc)192 PS / 141 kW1996–2000SLK 200 Kompressor★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,800–£3,200 [PLACEHOLDER — confirm vs cost sheet]

M111.973M111Petrol, supercharged2.3L (2295cc)193 PS / 142 kW1996–2000SLK 230 Kompressor★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,000–£3,500 [PLACEHOLDER — confirm vs cost sheet]

M111.978M111Petrol, supercharged2.0L (1998cc)163 PS / 120 kW2000–2004SLK 200 Kompressor (facelift)★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,800–£3,200 [PLACEHOLDER — confirm vs cost sheet]

M111.973 (updated)M111Petrol, supercharged2.3L (2295cc)197 PS / 145 kW2000–2004SLK 230 Kompressor (facelift)★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,000–£3,500 [PLACEHOLDER — confirm vs cost sheet]

M112.947M112Petrol3.2L (3199cc)218 PS / 160 kW2000–2004SLK 320★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,500–£4,500 [PLACEHOLDER — confirm vs cost sheet]

M112.960M112Petrol, supercharged3.2L (3199cc)354 PS / 260 kW2001–2004SLK 32 AMG★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£4,000–£7,000 [PLACEHOLDER — confirm vs cost sheet]

Engine CodeFuelPowerYearsReliabilityEnquiriesAvg. Recon Cost

M111.946M111Petrol136 PS / 100 kW1996–2000★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,500–£2,800 [PLACEHOLDER — confirm vs cost sheet]

M111.943M111Petrol, supercharged192 PS / 141 kW1996–2000★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,800–£3,200 [PLACEHOLDER — confirm vs cost sheet]

M111.973M111Petrol, supercharged193 PS / 142 kW1996–2000★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,000–£3,500 [PLACEHOLDER — confirm vs cost sheet]

M111.978M111Petrol, supercharged163 PS / 120 kW2000–2004★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£1,800–£3,200 [PLACEHOLDER — confirm vs cost sheet]

M111.973 (updated)M111Petrol, supercharged197 PS / 145 kW2000–2004★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,000–£3,500 [PLACEHOLDER — confirm vs cost sheet]

M112.947M112Petrol218 PS / 160 kW2000–2004★★★★☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£2,500–£4,500 [PLACEHOLDER — confirm vs cost sheet]

M112.960M112Petrol, supercharged354 PS / 260 kW2001–2004★★★☆☆ [PROVISIONAL — pending dedicated Engine Page]— (pattern data)£4,000–£7,000 [PLACEHOLDER — confirm vs cost sheet]

Overview

Mercedes SLK R170 — Overview

The R170 is the first-generation Mercedes-Benz SLK-Class, the compact luxury roadster that pioneered the folding metal roof — the 'vario-roof' — in the modern era.

Produced from 1995 to 2004 and based on a shortened W202 C-Class platform, the SLK combined open-top driving with year-round usability. The engine range spanned M111 four-cylinder petrols — both naturally aspirated and supercharged — plus the M112 V6 in the SLK 320 and the supercharged M112 V6 in the range-topping SLK 32 AMG. A 2000 facelift brought updated engines and styling, with over 300,000 examples produced before the R171 replaced it in 2004.

Key Facts

Platform

Mercedes W202 (shortened)

Predecessor

None (first SLK)

Successor

Mercedes-Benz SLK-Class (R171)

Sibling body styles in this generation

None (SLK is a standalone model)

Market Intelligence

The R170 SLK generated UK engine enquiries in 2025 [PATTERN DATA], with the M111 Kompressor engines and M112 V6 remaining the most commonly discussed among specialists.

Mercedes SLK R170 — Overview

The R170 is the first-generation Mercedes-Benz SLK-Class, the compact luxury roadster that pioneered the folding metal roof — the 'vario-roof' — in the modern era.

Produced from 1995 to 2004 and based on a shortened W202 C-Class platform, the SLK combined open-top driving with year-round usability. The engine range spanned M111 four-cylinder petrols — both naturally aspirated and supercharged — plus the M112 V6 in the SLK 320 and the supercharged M112 V6 in the range-topping SLK 32 AMG. A 2000 facelift brought updated engines and styling, with over 300,000 examples produced before the R171 replaced it in 2004.

Key Facts

Platform

Mercedes W202 (shortened)

Predecessor

None (first SLK)

Successor

Mercedes-Benz SLK-Class (R171)

Sibling body styles in this generation

None (SLK is a standalone model)

Market Intelligence

The R170 SLK generated UK engine enquiries in 2025 [PATTERN DATA], with the M111 Kompressor engines and M112 V6 remaining the most commonly discussed among specialists.

Best & Worst Engines

Thin-Data Summary

“Thin-Data Fallback mode — one paragraph: The R170's most dependable engine is the M112 3.2-litre V6 (SLK 320, 218 PS) — widely regarded as one of the best engines Mercedes ever produced, offering smooth power delivery, proven durability, and no major systemic failures. The post-facelift M111.978 2.0-litre Kompressor (SLK 200, 163 PS) is the best four-cylinder option — the 2000 facelift addressed many of the earlier M111's issues with improved engine management and reliability. The M111.973 2.3-litre Kompressor (SLK 230, 193–197 PS) is the most common engine and is generally robust, though timing chain and variable timing gear issues are documented. The SLK 32 AMG (354 PS) is a genuine modern classic — the supercharged V6 offers epic performance but carries higher running costs and supercharger clutch wear is common. Avoid any pre-facelift M111 without documented timing chain or variable timing gear history, and be cautious of oil migration from the cam magnet into the ECU wiring loom — a well-known M111 weakness.”

Who it's for:

Thin-Data Summary

“Thin-Data Fallback mode — one paragraph: The R170's most dependable engine is the M112 3.2-litre V6 (SLK 320, 218 PS) — widely regarded as one of the best engines Mercedes ever produced, offering smooth power delivery, proven durability, and no major systemic failures. The post-facelift M111.978 2.0-litre Kompressor (SLK 200, 163 PS) is the best four-cylinder option — the 2000 facelift addressed many of the earlier M111's issues with improved engine management and reliability. The M111.973 2.3-litre Kompressor (SLK 230, 193–197 PS) is the most common engine and is generally robust, though timing chain and variable timing gear issues are documented. The SLK 32 AMG (354 PS) is a genuine modern classic — the supercharged V6 offers epic performance but carries higher running costs and supercharger clutch wear is common. Avoid any pre-facelift M111 without documented timing chain or variable timing gear history, and be cautious of oil migration from the cam magnet into the ECU wiring loom — a well-known M111 weakness.”

Who it's for:

Mercedes SLK R170 — Ownership Economics

EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership Verdict

M111.946 (SLK 200)80k–130kTiming chain wear, MAF sensor£300–£600£1,500–£2,800

Entry Choice — simplest R170 to run

M111.943 (SLK 200 Kompressor pre-facelift)60k–100kSupercharger clutch, timing chain, cam magnet oil leak£500–£1,000£1,800–£3,200

Early Kompressor — more power, more to maintain

M111.973 (SLK 230 Kompressor pre-facelift)60k–100kSupercharger clutch, variable timing gear, oil in loom£500–£1,000£2,000–£3,500

Strong Four — 193 PS, common but known issues

M111.978 (SLK 200 Kompressor facelift)60k–100kSupercharger clutch, MAF sensor£400–£800£1,800–£3,200

Improved Kompressor — 163 PS, better reliability

M111.973 (SLK 230 Kompressor facelift)60k–100kSupercharger clutch, variable timing gear£400–£800£2,000–£3,500

Best Four — 197 PS, facelift improvements

M112.947 (SLK 320)80k–130kValve cover gaskets, crank position sensor£300–£600£2,500–£4,500

Most Reliable — the V6 sweet spot

M112.960 (SLK 32 AMG)40k–80kSupercharger clutch, crank position sensor£800–£1,500£4,000–£7,000

AMG Icon — epic V6, epic bills

EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership Verdict

M111.946 (SLK 200)80k–130kTiming chain wear, MAF sensor£300–£600£1,500–£2,800

Entry Choice — simplest R170 to run

M111.943 (SLK 200 Kompressor pre-facelift)60k–100kSupercharger clutch, timing chain, cam magnet oil leak£500–£1,000£1,800–£3,200

Early Kompressor — more power, more to maintain

M111.973 (SLK 230 Kompressor pre-facelift)60k–100kSupercharger clutch, variable timing gear, oil in loom£500–£1,000£2,000–£3,500

Strong Four — 193 PS, common but known issues

M111.978 (SLK 200 Kompressor facelift)60k–100kSupercharger clutch, MAF sensor£400–£800£1,800–£3,200

Improved Kompressor — 163 PS, better reliability

M111.973 (SLK 230 Kompressor facelift)60k–100kSupercharger clutch, variable timing gear£400–£800£2,000–£3,500

Best Four — 197 PS, facelift improvements

M112.947 (SLK 320)80k–130kValve cover gaskets, crank position sensor£300–£600£2,500–£4,500

Most Reliable — the V6 sweet spot

M112.960 (SLK 32 AMG)40k–80kSupercharger clutch, crank position sensor£800–£1,500£4,000–£7,000

AMG Icon — epic V6, epic bills

The R170 rule

A £2,000–£3,500 recon on a sub-£4,000 R170 sits at 50–88% of the car's value — a serious decision. Against a well-kept £7,000+ example, the same recon drops to 29–50% — viable. For an SLK 32 AMG, a £12,000+ car justifies a £4,000–£7,000 recon. Our 70% Mercedes-Benz threshold is the line — value the car first, then the engine.

Key Takeaways

Which R170 Costs Least To Own?
SLK 200 (M111.946) — simplest engine, cheapest parts, no supercharger.
Which R170 Costs Most To Own?
SLK 32 AMG (M112.960) — supercharged V6 complexity, specialist-only work.
Which R170 Is Best Value?
SLK 320 (M112.947) — 218 PS V6, proven reliability, strong performance without AMG running costs.

Common Problems

01

M111

Kompressor Supercharger Clutch & Timing Chain Issues

Affected models:

R170 SLK 200 Kompressor, SLK 230 Kompressor (all M111 supercharged variants).

M111 Kompressor Supercharger Clutch & Timing Chain Issues

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The Eaton supercharger's electromagnetic clutch can fail, causing a loss of boost and a rattling noise. Timing chain issues are also reported on the M111 — tensioners can fail or drive sprocket lobes can wear down, causing chain slip. The variable timing gear is also prone to issues, with a rattle when revved indicating a failing magnet or complete timing adjuster mechanism failure. Oil from the cam magnet can also migrate into the wiring loom and ECU.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£800–£1,200

£500–£800

Replace supercharger clutch, timing chain tensioner, cam magnet seal

Catastrophic (Replacement)

Dealer

Specialist

£2,500–£4,000

£1,800–£3,200

Full timing chain and supercharger overhaul

Our Recommendation

If your Kompressor is down on power, rattling, or has an engine warning light for timing faults, have the supercharger clutch and timing system inspected immediately — £500–£800 is far cheaper than the £1,800+ replacement that follows if the chain slips or the supercharger fails internally. Install the modified piggyback loom from Mercedes (£20) to prevent oil migration into the ECU.

Compare M111 engine prices for your R170 SLK

02

M112

V6 Valve Cover Gaskets & Crank Position Sensor

Affected models:

R170 SLK 320 (M112.947 V6), SLK 32 AMG (M112.960 supercharged V6).

M112 V6 Valve Cover Gaskets & Crank Position Sensor

Typical failure mileage:

80,000–130,000 miles.

Root cause:

The M112 V6 is considered one of the most reliable Mercedes engines, but two common issues are valve cover gasket leaks (which can be DIY-repaired) and crank position sensor failure. The engine management relay can also fail, causing rough idle, engine stumbling, or stalling.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£500–£800

£300–£500

Replace valve cover gaskets, crank position sensor

Catastrophic (Replacement)

Dealer

Specialist

£2,500–£4,000

£2,000–£3,500

Full engine management diagnosis and repair

Our Recommendation

Have the valve cover gaskets inspected at every service — £300–£500 in preventative work is cheap insurance against oil leaks damaging other components. If the engine stumbles or stalls, have the crank position sensor and engine management relay checked immediately.

Compare M112 engine prices for your R170 SLK 320

03

M112.960

AMG Supercharger Clutch Wear

Affected models:

R170 SLK 32 AMG (M112.960 supercharged V6).

Typical failure mileage:

40,000–80,000 miles.

Root cause:

The SLK 32 AMG's supercharger uses an electromagnetic clutch that engages under load. A squeak from the supercharger is normal — it's the clutch engaging and disengaging. However, excessive wear can lead to clutch failure, loss of boost, and reduced performance. Replacing the entire supercharger unit is expensive and should only be done if there is a genuine problem.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£800–£1,200

£500–£800

Replace supercharger clutch and belt

Catastrophic (Replacement)

Dealer

Specialist

£3,500–£5,500

£3,000–£5,000

Full supercharger replacement if internal damage

Our Recommendation

A squeak from the supercharger is normal and not necessarily a cause for concern. However, if the car is down on power or the supercharger is making excessive noise, have the clutch inspected — a £500–£800 repair is far cheaper than the £3,000+ replacement that follows if the supercharger fails internally.

Compare M112 AMG engine prices for your R170 SLK 32 AMG

04

R170

Vario-Roof Hydraulic System Failure

Affected models:

All R170 SLK variants (vario-roof system).

R170 Vario-Roof Hydraulic System Failure

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The R170's electro-hydraulic folding roof is the car's defining feature, but it's also a common failure point. Failed micro-switches, tired hydraulic rams, leaks in the system, or issues with the Combined Control Module (CCM) can all prevent the roof from operating correctly. A roof in good condition should raise and lower in 25–30 seconds.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£800–£1,200

£500–£800

Replace hydraulic fluid, micro-switches, CCM diagnosis

Catastrophic (Replacement)

Dealer

Specialist

£2,500–£4,000

£1,800–£3,000

Full hydraulic system overhaul including rams and pump

Our Recommendation

Preventative maintenance is key — change the hydraulic fluid if it appears dark rather than golden. Have the roof mechanism inspected at every service — £500–£800 in preventative work is a fraction of the £1,800+ bill if the pump or rams fail completely. Don't despair if the roof isn't functioning correctly; there's plenty of specialist expertise available.

Compare R170 vario-roof repair quotes

R170 Engine Replacement Costs — By Engine and Condition

VariantEngine CodeUsed (Supply)Reconditioned (Supply)Rebuilt (Supply)Labour Hours

SLK 200M111.946£700–£1,400£1,500–£2,800£2,500–£4,0008–12 hrs

SLK 200 Kompressor (pre-facelift)M111.943£900–£1,600£1,800–£3,200£3,000–£5,00010–14 hrs

SLK 230 Kompressor (pre-facelift)M111.973£1,000–£1,800£2,000–£3,500£3,200–£5,20010–14 hrs

SLK 200 Kompressor (facelift)M111.978£900–£1,600£1,800–£3,200£3,000–£5,00010–14 hrs

SLK 230 Kompressor (facelift)M111.973£1,000–£1,800£2,000–£3,500£3,200–£5,20010–14 hrs

SLK 320M112.947£1,200–£2,500£2,500–£4,500£4,000–£6,50012–16 hrs

SLK 32 AMGM112.960£2,000–£3,800£4,000–£7,000£6,000–£9,00014–18 hrs

Core Variants

Petrol Variants

SLK 200SLK 200 KompressorSLK 230 KompressorSLK 320SLK 32 AMG

Scope note: All variants listed are R170 roadster only. The R170 was produced from October 1995 to April 2004, with a facelift in 2000 bringing updated engines and styling. The SLK 32 AMG was introduced in 2001 as the range-topping model.

Core Variants

Petrol Variants

SLK 200SLK 200 KompressorSLK 230 KompressorSLK 320SLK 32 AMG

Scope note: All variants listed are R170 roadster only. The R170 was produced from October 1995 to April 2004, with a facelift in 2000 bringing updated engines and styling. The SLK 32 AMG was introduced in 2001 as the range-topping model.

Market Intelligence

Most Requested E90 Engines (2025)

Most Requested E90 Variants

Average E90 Replacement Cost

Most Common E90 Failures

FAQ

BMW 3 Series E90 rear three-quarter view

Why UK Mercedes SLK R170 Owners Trust MercedesEngines.uk

Trusted R170 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real Mercedes owners, as part of the Engine Finders network. We only work with specialists who understand the R170's M111 Kompressor and vario-roof intricacies.
Compare R170 Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit. Whether you need a reconditioned M112 or a used M111, we show you the real market.
UK Engine Replacement Services for R170
covering every variant from SLK 200 to SLK 32 AMG, with supply-only or full supply & fit available nationwide through our vetted specialist network.

Find the best Mercedes SLK R170 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.

Compare Mercedes SLK R170 Engine Prices on EnginesMarket

Why UK Mercedes SLK R170 Owners Trust MercedesEngines.uk

Trusted R170 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real Mercedes owners, as part of the Engine Finders network. We only work with specialists who understand the R170's M111 Kompressor and vario-roof intricacies.
Compare R170 Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit. Whether you need a reconditioned M112 or a used M111, we show you the real market.
UK Engine Replacement Services for R170
covering every variant from SLK 200 to SLK 32 AMG, with supply-only or full supply & fit available nationwide through our vetted specialist network.

Find the best Mercedes SLK R170 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.

Compare Mercedes SLK R170 Engine Prices on EnginesMarket

Mercedes SLK R170 Engines — The Complete UK Guide

Mercedes SLK R170 Engine Codes — The Complete Database

Mercedes SLK R170 — Overview

Mercedes SLK R170 — Overview

Best & Worst Engines

Mercedes SLK R170 — Ownership Economics

Common Problems

R170 Engine Replacement Costs — By Engine and Condition

Core Variants

Core Variants

Market Intelligence

FAQ

Why UK Mercedes SLK R170 Owners Trust MercedesEngines.uk

Why UK Mercedes SLK R170 Owners Trust MercedesEngines.uk