BMW 8 Series 840i Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK BMW 8 Series 840i engine specialists. Compare prices on reconditioned, rebuilt and used engines for your 840i - all with a minimum 12-month warranty.
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12-Month Warranty
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From £3,800 to £6,000
Used from £2,000 · Reconditioned from £3,800 · Common codes: B58B30, B58B30C, B58B30M0, B58B30M1
From £2,000
Tested, bare/short engine
From £3,800
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best BMW 8 Series 840i Replacement Engineto Finding the Best BMW 8 Series 840i Replacement Engine
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Variant HistoryBMW 8 Series 840i - Engine History & Specs at a Glance
The BMW 8 Series 840i launched in July 2019 as the entry-level petrol model in the revived G15 8 Series range, powered by BMW's acclaimed B58 3.0-litre straight-six. The 840i has remained the core petrol variant across Coupe (G15), Convertible (G14) and Gran Coupe (G16) body styles, with power outputs varying slightly between 333hp and 340hp depending on year and market.
Variant HistoryBMW 8 Series 840i - Engine History & Specs at a Glance
The BMW 8 Series 840i launched in July 2019 as the entry-level petrol model in the revived G15 8 Series range, powered by BMW's acclaimed B58 3.0-litre straight-six. The 840i has remained the core petrol variant across Coupe (G15), Convertible (G14) and Gran Coupe (G16) body styles, with power outputs varying slightly between 333hp and 340hp depending on year and market.
BMW 8 Series 840i
Fuel TypePetrol
Engine Size Range3.0L (2,998cc)
Power Output Range333-340hp across the variant's historyEngine History Timeline
July 2019 - B58B30 (340hp 500Nm), 3.0-litre twin-power turbo inline-six, launch specification for Coupe and Convertible
B58B30C variant introduced 340hp, fitted to 840i xDrive models
Power output adjusted to 333hp in some UK-market 840i variants; B58B30M0 and B58B30M1 codes appear
March 2022 - G15 LCI (facelift) introduced; 840i xDrive produces 333hp @ 5500-6250rpm 500Nm @ 1700-4000rpm
present - B58B30C remains the primary engine code across 840i models
Key Specs Snapshot
Fuel TypePetrolEngine Size Range3.0L (2,998cc)Power Output Range333-340hp across the variant's historyYears Produced2019-presentEvery engine fitted to the BMW 8 Series 840i is covered below, with UK rebuilt pricing and known failure points.
BMW 8 Series 840i Engine Codes - Specifications & Replacement CostBMW 8 Series 840i Engine Codes - Specifications & Replacement Cost
3.0L Petrol (2019-2020)
Power Output340hp @ 5000-6500rpmYears Fitted2019-2020
Compatible Trim Levels
- 840i
- 840i M Sport
- 840i xDrive
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£2,000-£3,800
Reconditioned
Addressed known issues, tested
£3,800-£6,000
Rebuilt
Full teardown, upgraded internals
£5,000-£8,000
Common Failure
Coolant leaks from the expansion tank, water pump and plastic fittings; PCV valve failure; high-pressure fuel pump issues. Typically appears between 60k-120k miles. Water pump replacement: £500-£1,000; PCV valve: £400-£800. These are well-understood issues with relatively inexpensive repairs compared to other BMW engines.【17†L7-L9】
The BMW 8 Series 840i's B58 engine is widely regarded as one of BMW's most robust modern powerplants, but it has several well-documented weak points. The B58 family - fitted to every 840i since launch - is fundamentally reliable, but coolant system failures, PCV valve issues and fuel system problems do occur, typically from 60,000 miles onward. Rebuilt B58 engines supplied through EnginesMarket include upgraded components addressing the original failure points, plus a minimum 12-month unlimited-mileage warranty.
Why the BMW 8 Series 840i B58 Engine Loses Coolant Prematurely
Affected Vehicles
BMW 8 Series 840i (B58B30 / B58B30C, 2019-present)
Typical Failure Mileage
60k-120k miles
Root Cause
The B58 engine uses plastic water pump housings, expansion tank fittings and coolant crossover pipes that become brittle with heat cycling. Cracks develop, causing slow or sudden coolant loss. Overheating can lead to head gasket failure if not caught early.【17†L7-L9】
Why It Happens
The B58 engine uses plastic water pump housings, expansion tank fittings and coolant crossover pipes that become brittle with heat cycling. Cracks develop, causing slow or sudden coolant loss. Overheating can lead to head gasket failure if not caught early.【17†L7-L9】
Dealer (parts + labour)
£800-£1,400
Specialist (parts + labour)
£500-£1,000
What it involves
Replace water pump and thermostat, coolant flush
Suitability
Preventative; suitable for 60k+ mile cars
1 - 2 daysDealer (parts + labour)
£1,200-£2,000
Specialist (parts + labour)
£800-£1,500
What it involves
Replace pump, expansion tank, hoses, crossover pipes
Suitability
Comprehensive fix for cars with multiple leaks
1 - 2 daysDealer (parts + labour)
£7,500-£10,000
Specialist (parts + labour)
£5,000-£8,000
What it involves
Supply & fit, upgraded components addressing the original failure point, 12-month warranty
Suitability
When overheating has caused internal damage (warped head, failed head gasket)
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 |
|---|---|---|---|---|---|
 Water pump replacement Minor | £800-£1,400 | £500-£1,000 | Replace water pump and thermostat, coolant flush | Preventative; suitable for 60k+ mile cars | 1 - 2 days |
 Coolant system overhaul Best Value | £1,200-£2,000 | £800-£1,500 | Replace pump, expansion tank, hoses, crossover pipes | Comprehensive fix for cars with multiple leaks | 1 - 2 days |
Full Replacement - rebuilt/reconditioned engine Best Value | £7,500-£10,000 | £5,000-£8,000 | Supply & fit, upgraded components addressing the original failure point, 12-month warranty | When overheating has caused internal damage (warped head, failed head gasket) | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical BMW 8 Series 840i (2019-2022) is worth approximately £30,000-£55,000, with newer examples (2023-2025) valued at £50,000-£90,000+. The 840i sits in the £15,000+ band: replacement cost is typically small relative to vehicle value. A £5,000-£8,000 rebuilt engine is a financially sound investment for a car worth £30,000-£55,000.
Our Recommendation
Our Recommendation
For a BMW 8 Series 840i, coolant system repairs are almost always worthwhile given the high residual value of the car. If caught early (before overheating), a water pump or coolant system overhaul is the sensible choice. If the engine has been overheated and internal damage is suspected, a rebuilt B58 with upgraded components offers better long-term reliability than a patch-and-repair approach on a damaged block.
Don't Let Engine Failure Write Off Your BMW 8 Series 840i
The BMW 8 Series 840i's B58 engine is fundamentally robust, but coolant leaks, PCV valve failure and HPFP issues do occur from 60,000 miles onward. With 840i values starting at £30,000+, a rebuilt engine from £3,800-£6,000 (supply-only) or £5,000-£8,000 fitted is a sound investment that preserves the car's value and delivers years of reliable service. Every rebuilt B58 supplied through EnginesMarket includes upgraded components addressing the original failure points and a minimum 12-month unlimited-mileage warranty - compare specialist quotes today and avoid main dealer premiums.
Compare rebuilt B58B30 BMW 8 Series 840i 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 BMW 8 Series 840i. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW 8 Series 840i Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW 8 Series 840i engine replacement cost in the UK-
A BMW 8 Series 840i engine replacement typically costs £3,800-£6,000 for a reconditioned supply-only B58 unit, or £5,000-£8,000 fitted by a specialist. Used engines start from £2,000 but carry higher risk. Dealer prices can reach £7,500-£10,000+ for a full replacement.
- Reconditioned B58 (supply-only): £3,800-£6,000
- Rebuilt B58 (supply & fit): £5,000-£8,000
- Used B58 (supply-only): £2,000-£3,800
Question 2What are the signs of B58 engine failure in a BMW 8 Series 840i-
Common warning signs include coolant loss (often from the expansion tank, water pump or plastic fittings), whistling noises from the engine (PCV valve failure), loss of power or misfires (HPFP or injector issues), and the inability to measure engine oil (oil pump failure warning).
- Coolant warning light or repeated low coolant top-ups
- Whistling or hissing from the engine bay
- Rough idle, misfires or hesitation under acceleration
- Engine oil pressure warning
Question 3Is it worth replacing the engine in a BMW 8 Series 840i-
Yes - a BMW 8 Series 840i is worth £30,000-£90,000+ depending on age and mileage. A £5,000-£8,000 rebuilt engine is a fraction of the car's value and preserves its long-term reliability. For cars worth under £15,000, evaluate carefully; but the 840i comfortably exceeds this threshold.
- 840i values typically £30,000-£55,000 (2019-2022)
- Newer examples (2023-2025): £50,000-£90,000+
- Rebuilt engine cost: 10-20% of vehicle value
Question 4How long does a BMW 8 Series 840i engine replacement take-
A BMW 8 Series 840i engine replacement typically takes 10-14 labour hours for a specialist workshop, spread over 2-3 working days depending on parts availability. The B58's longitudinal mounting and 8-speed ZF transmission make access straightforward compared to transverse layouts.
- Specialist labour: 10-14 hours @ £65-£85/hr
- Typical turnaround: 2-3 working days
- Main dealer: typically longer and more expensive
Question 5What's the difference between the BMW 840i and BMW 840d engines-
The BMW 840i uses the B58 3.0-litre twin-power turbo petrol straight-six (333-340hp), while the 840d uses the B57 3.0-litre twin-turbo diesel straight-six (320hp). The 840i is lighter, revs more freely and suits drivers prioritising refinement; the 840d offers higher torque (680Nm vs 500Nm) and better fuel economy but carries EGR and DPF-related risks.
- 840i (petrol): B58, 333-340hp, 500Nm, 0-62mph in 5.0 sec
- 840d (diesel): B57, 320hp, 680Nm, 0-62mph in 5.1 sec
Question 6Should I repair or replace the engine in my BMW 8 Series 840i-
If the issue is coolant system-related (water pump, expansion tank, hoses), repair is usually the right choice - costs £500-£1,500 at a specialist. If the engine has been overheated causing head gasket or bottom-end damage, or if oil starvation has occurred, replacement with a rebuilt B58 is safer and often more cost-effective than a patchwork repair.
- Coolant system repair: £500-£1,500 -> repair
- PCV valve / HPFP: £400-£1,200 -> repair
- Overheating damage / oil starvation: £5,000-£8,000 -> replace with rebuilt engine
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