Mercedes Benz S Class 280/420 Petrol Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK Mercedes Benz S Class 280 and 420 petrol engine specialists. Compare prices on reconditioned, rebuilt and used engines for the 2.8-litre V6 and the 4.3-litre V8 - supply & fit available nationwide.
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From £2,200 to £4,800
Used from £1,200 · Reconditioned from £2,200 · Common codes: M112.922, M113.941
From £1,200
Tested, bare/short engine
From £2,200
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best Mercedes Benz S Class 280/420 Petrol Replacement Engineto Finding the Best Mercedes Benz S Class 280/420 Petrol Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryMercedes Benz S Class 280/420 Petrol - Engine History & Specs at a Glance
The S 280 and S 420 launched with the W220 generation in 1998 as the entry-level V6 and mid-range V8 petrol flagships of Mercedes' luxury saloon range. The S 280 was powered by the M112 2.8-litre V6 producing 204hp, while the S 420 used the M113 4.3-litre V8 with 279hp. Both engines featured SOHC design with three valves per cylinder and timing chain drive, representing the pinnacle of Mercedes naturally aspirated engineering before the modern era of forced induction and direct injection. Production continued until 2005 when the W221 generation replaced the W220.
Variant HistoryMercedes Benz S Class 280/420 Petrol - Engine History & Specs at a Glance
The S 280 and S 420 launched with the W220 generation in 1998 as the entry-level V6 and mid-range V8 petrol flagships of Mercedes' luxury saloon range. The S 280 was powered by the M112 2.8-litre V6 producing 204hp, while the S 420 used the M113 4.3-litre V8 with 279hp. Both engines featured SOHC design with three valves per cylinder and timing chain drive, representing the pinnacle of Mercedes naturally aspirated engineering before the modern era of forced induction and direct injection. Production continued until 2005 when the W221 generation replaced the W220.
Mercedes Benz S Class 280/420 Petrol
Fuel TypePetrol (naturally aspirated V6 and V8)
Engine Size Range2.8L-4.3L (M112: 2,799cc; M113: 4,266cc)
Power Output Range204-279hp across the variant's historyEngine History Timeline
M112.922 2.8L V6 petrol, 204hp @ 5,700rpm (S 280, W220 launch)
M113.941 4.3L V8 petrol, 279hp @ 5,750rpm (S 420, W220 launch)
Minor ECU revisions to both engines for improved emissions
End of W220 production; replaced by W221 generation
Key Specs Snapshot
Fuel TypePetrol (naturally aspirated V6 and V8)Engine Size Range2.8L-4.3L (M112: 2,799cc; M113: 4,266cc)Power Output Range204-279hp across the variant's historyYears Produced1998-2005Every engine fitted to the Mercedes Benz S Class 280 and 420 petrol is covered below, with UK rebuilt pricing and known failure points - from M112 harmonic balancer failure to M113 oil leaks and ignition system issues.
Mercedes Benz S Class 280/420 Petrol Engine Codes - Specifications & Replacement CostMercedes Benz S Class 280/420 Petrol Engine Codes - Specifications & Replacement Cost
2.8L V6 Petrol (1998-2005)
Power Output204 hp (150 kW) @ 5,700 rpmTorque270 Nm @ 3,000-5,000 rpmYears Fitted1998-2005Displacement2,799 cc (2.8L)CylindersV6, 90° V-angle, SOHC, 18-valveEngine CodeM 112 E 28 / 112.922
Compatible Trim Levels
- S 280
- S 280 4MATIC
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,200-£2,000
Reconditioned
Addressed known issues, tested
£2,200-£3,200
Rebuilt
Full teardown, upgraded internals
£2,500-£3,800
Common Failure
Harmonic balancer (crankshaft pulley) rubber separation - the M112's harmonic balancer has a bonded rubber layer that deteriorates with age and heat cycling, causing the outer ring to slip or separate. Valve cover breather oil leaks and variable intake flap sticking are also common. Typical failure mileage: 80,000-150,000 miles.
The S 280's M112 V6 and the S 420's M113 V8 are among Mercedes' most robust naturally aspirated petrol engines - renowned for their durability and longevity. However, with age and mileage, both have well-documented weaknesses that can lead to significant repair costs. The M112 is prone to harmonic balancer failure and oil leaks, while the M113 suffers from oil leaks, ignition system issues, and sensor failures. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing these original failure points, plus a minimum 12-month unlimited-mileage warranty.
The S 280's Signature Weakness
Affected Vehicles
Mercedes S 280 (M112.922, 1998-2005)
Typical Failure Mileage
80,000-150,000 miles
Root Cause
The M112's harmonic balancer (crankshaft pulley) has a bonded rubber layer that deteriorates with age, heat cycling, and exposure to oil and contaminants. This can cause the outer ring to separate at speed, potentially leading to catastrophic engine damage. This is the signature failure of the M112 engine family.
Why It Happens
The M112's harmonic balancer (crankshaft pulley) has a bonded rubber layer that deteriorates with age, heat cycling, and exposure to oil and contaminants. This can cause the outer ring to separate at speed, potentially leading to catastrophic engine damage. This is the signature failure of the M112 engine family.
Dealer (parts + labour)
£100-£200
Specialist (parts + labour)
£80-£150
What it involves
Visual inspection of harmonic balancer for cracks or rubber deterioration
Suitability
Recommended for all M112 engines at 80,000+ miles
1 - 2 daysDealer (parts + labour)
£600-£1,000
Specialist (parts + labour)
£400-£700
What it involves
Replace crankshaft harmonic balancer, inspect belts and pulleys
Suitability
If cracks or wobble are detected
1 - 2 daysDealer (parts + labour)
£4,500-£6,000
Specialist (parts + labour)
£2,500-£3,800
What it involves
Complete engine swap with new harmonic balancer and seals, 12-month warranty
Suitability
If balancer failure has caused engine damage
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Preventative - Harmonic balancer inspection Minor | £100-£200 | £80-£150 | Visual inspection of harmonic balancer for cracks or rubber deterioration | Recommended for all M112 engines at 80,000+ miles | 1 - 2 days |
 Intermediate - Harmonic balancer replacement Best Value | £600-£1,000 | £400-£700 | Replace crankshaft harmonic balancer, inspect belts and pulleys | If cracks or wobble are detected | 1 - 2 days |
Full Replacement - Rebuilt M112 engine Best Value | £4,500-£6,000 | £2,500-£3,800 | Complete engine swap with new harmonic balancer and seals, 12-month warranty | If balancer failure has caused engine damage | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 1998-2005 S 280 or S 420 is worth approximately £3,000-£10,000 depending on condition and mileage. These flagship saloons have depreciated significantly, meaning replacement costs can approach vehicle value for higher-mileage examples.
Our Recommendation
Our Recommendation
The M112's harmonic balancer is a known weakness with age. If you notice unusual noises from the passenger side of the engine bay or any wobble from the main crank pulley, do not drive the vehicle. Specialist harmonic balancer replacement at £400-£700 is significantly cheaper than dealer rates. On an S 280 worth £3,000-£10,000, preventative attention to this issue is always the better investment.
Don't Let Harmonic Balancer Failure, Oil Leaks, or Ignition Issues Write Off Your Mercedes S 280 or 420 Petrol
Whether you're facing M112 harmonic balancer failure on your S 280, oil leaks on your S 420, or ignition system issues, EnginesMarket makes it simple to compare quotes from trusted UK Mercedes petrol specialists. Every rebuilt engine in our network carries upgraded components addressing the original design weakness - new harmonic balancers, fresh gaskets and seals, and fully tested ignition systems - 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 Mercedes specialists who know these classic V6 and V8 engines inside out.
Compare rebuilt M112 Mercedes S 280 engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific Mercedes S Class 280 or 420 petrol. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Mercedes Benz S Class 280/420 Petrol Engine ReplacementFrequently Asked Questions
Question 1How much does a Mercedes S 280 or S 420 petrol engine replacement cost in the UK-
Short summary: A rebuilt M112 engine for the S 280 costs £2,500-£3,800 supply-only; a rebuilt M113 V8 for the S 420 costs £3,200-£4,800 supply-only. Fitting adds £1,200-£2,500 depending on complexity - V8 work requires specialist knowledge.
- S 280 (M112.922): rebuilt unit £2,500-£3,800; used engine from £1,200
- S 420 (M113.941): rebuilt unit £3,200-£4,800; used engine from £1,500
- M112 harmonic balancer replacement: £400-£700 at specialist
- M113 oil leak repair (valve cover gaskets): £250-£550 at specialist
Question 2What are the signs of harmonic balancer failure on a Mercedes S 280-
Short summary: Unusual noises from the passenger side of the engine bay, vibration, or visible cracks in the rubber of the harmonic balancer are the classic warning signs on the M112 engine. If you notice any wobble from the main crank pulley, do not drive the vehicle.
- Unusual noises from the passenger side of the engine bay
- Visible cracks or rubber deterioration on the harmonic balancer
- Engine vibration at idle or under load
- If caught early, replacement costs £400-£700 at specialist
Question 3Is the Mercedes S 280 or S 420 petrol engine reliable-
Short summary: Both the M112 V6 and the M113 V8 are among Mercedes' most robust engines. The M113 is widely regarded as one of the most reliable German V8 engines ever built, capable of exceeding 300,000 miles with diligent maintenance. However, age-related issues like oil leaks, harmonic balancer failure, and ignition system wear are common and should be addressed proactively.
- M112 and M113 are fundamentally robust - 200,000+ miles common
- Harmonic balancer failure is the M112's signature weakness
- M113 oil leaks affect approximately 30% of engines
- Regular oil changes with MB 229.5 spec oil are essential
Question 4How long do Mercedes S 280 and S 420 petrol engines last-
Short summary: Properly maintained M112 and M113 engines routinely reach 200,000+ miles before major work is needed. One owner reported an M113 engine exceeding 340,000 miles (500,000 km) with regular maintenance.
- M112 (S 280): 200,000+ miles with regular servicing
- M113 (S 420): 200,000-300,000+ miles with proper maintenance
- Harmonic balancer inspection recommended from 80,000 miles on M112
- Service interval is 10,000 miles or 12 months - use Mercedes-spec MB 229.5 oil
Question 5Is it worth replacing the engine in my Mercedes S 280 or S 420 petrol-
Short summary: Yes, if the S Class is otherwise in good condition with no rust or major transmission faults. A rebuilt M112 costs £2,500-£3,800 - comparable to the value of a £3,000-£10,000 vehicle. The S 420's higher specification makes replacement even more justifiable for well-maintained examples.
- S 280 values: £3,000-£8,000 depending on condition
- S 420 values: £3,000-£10,000 - flagship V8 models retain stronger values
- Rebuilt engine with upgraded components fixes original weak points
- Supply & fit typically £3,700-£7,300 depending on engine code
- New engine includes 12-month unlimited mileage warranty
Question 6What oil does my Mercedes S 280 or S 420 petrol need-
Short summary: Mercedes-Benz specifies MB 229.5 high-performance oil - typically 5W-30 or 5W-40 fully synthetic. The M112 V6 requires approximately 7.5 litres; the M113 V8 requires approximately 8.0 litres.
- M112 (S 280): MB 229.5 5W-30 or 5W-40 - 7.5L capacity
- M113 (S 420): MB 229.5 5W-30 or 5W-40 - 8.0L capacity
- Never use non-approved oil - can cause timing chain and hydraulic lifter issues
- Change every 10,000 miles or 12 months
Why Choose UsCompare Mercedes S Class 280/420 PetrolEngine PricesToday
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12-Month Warranty on every rebuilt S 280 and S 420 petrol engine
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supply & fit available for M112 and M113
Comparing quotes for your Mercedes S 280 or S 420 petrol is completely free, with no obligation and no pressure. Enter your registration above to get tailored quotes from UK Mercedes petrol specialists who understand the M112 V6 and M113 V8 engines inside out. Whether you need a used engine, a reconditioned unit, or a full rebuilt engine with upgraded harmonic balancers, new gaskets, and fresh ignition components, we'll connect you with the right specialist for your exact S Class - with a minimum 12-month warranty on every engine supplied.
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