E31
1990–1999
• M60B40 V8, M62B44 V8, M70B50 V12, M73B54 V12, S70B56 V12 (850CSi)
BMW 8 Series1990–1999, 2018–20262 Generations (E31, G14/G15/G16)M60, M62, M70, M73, S70, B58, N63, S63, B57
8 Series Engines –
The Complete UK Guide
Every BMW 8 Series engine across two generations and three body styles - from the M70 V12 of the original E31 to the B58 straight-six and N63 V8 of the modern G15. Real UK replacement costs, known failure patterns, and honest ownership economics for BMW's grand tourer flagship. Backed by 150+ real UK 8 Series engine enquiries in 2025 [BMW-VERIFIED].
Explore 8 Series Engines- 150+Enquiries (2025)[BMW-VERIFIED]
- 2Generations, 3 Body Styles
- 10+Engine Codes
- Part ofEngine Finders
BMW 8 Series -
The Ownership Verdict
One-line verdict:
The 8 Series is BMW's grand tourer flagship - beautiful, powerful, and expensive to keep. The B58 840i is the sensible choice; the N63 M850i is the emotional one. On the modern car, buy the straight-six unless you have the budget for V8 bills. On the E31, buy the V12 and treat it as a restoration project.
Verdict MetricOur Call
Overall Ownership Rating
½ (3.5/5)
Replacement Economics
The 8 Series rule - grand tourer, grand bills: an N63 recon at £7,000–£12,000 against a £30,000 used G15 850i is 23–40% of the car's value - ⚠️ watch. Against a £100,000 G16, the same repair is just 7–12% - ✅ safe. The E31 is now a classic where engine work is restoration, not repair.
Reliability
- the B58 straight-six is the modern gold standard; the N63 V8 carries the hot-vee caveats; the E31's V8s and V12s are ageing but fundamentally robust.
Most Reliable Engine
B58B30 (840i) - the most dependable modern BMW engine - and the M70/M73 V12 in the E31, which are surprisingly durable
Highest-Risk Engine
N63B44 (M850i) - timing chain guides, valve stem seals, turbo failures, excessive oil consumption
Best Used Buy
G15 840i with B58 - the straight-six is bulletproof, the chassis is magnificent, and the V8 caveats don't apply
Best Performance Buy
G15 M850i with N63 - 523 bhp of twin-turbo V8, but budget £7,000–£12,000 for a recon and buy the best warranty
Average Engine Replacement
£5,500 reconditioned, supply only [BMW-QUOTE]
Most Common Failure Enquiry
N63 oil consumption / timing chain guides - shared-platform data [BMW-VERIFIED]
BMW Ranking
👑 The Flagship GT - BMW's most expensive non-M model and the car with the highest parts bills in the range
One-line verdict:
The 8 Series is BMW's grand tourer flagship - beautiful, powerful, and expensive to keep. The B58 840i is the sensible choice; the N63 M850i is the emotional one. On the modern car, buy the straight-six unless you have the budget for V8 bills. On the E31, buy the V12 and treat it as a restoration project.
BMW 8 Series
at a Glance
MetricValue
Generations2 (E31 1990–1999, G14/G15/G16 2018–2026)
Years Produced1990–1999, 2018–2026
Engine Codes Tracked10+
Fuel TypesPetrol, Diesel (modern), Mild-Hybrid (2020+)
Most Enquired Engine (2025)N63B44 / B58B30 - shared-platform dataBMW-VERIFIED
Most ReliableB58B30 (840i) / M70/M73 V12 (E31)
Highest-RiskN63B44 (M850i) - timing chain guides, valve stem seals, turbo failure
Typical Replacement Cost£2,800–£12,000 reconditionedBMW-QUOTE
Typical Host Value£15,000 (E31 project) – £100,000+ (new G16)
Overall Rating½ 3.5/5
Generations
2 (E31 1990–1999, G14/G15/G16 2018–2026)
Years Produced
1990–1999, 2018–2026
Engine Codes Tracked
10+
Fuel Types
Petrol, Diesel (modern), Mild-Hybrid (2020+)
Most Enquired Engine (2025)
N63B44 / B58B30 - shared-platform data
BMW-VERIFIEDMost Reliable
B58B30 (840i) / M70/M73 V12 (E31)
Highest-Risk
N63B44 (M850i) - timing chain guides, valve stem seals, turbo failure
Typical Replacement Cost
£2,800–£12,000 reconditioned
BMW-QUOTETypical Host Value
£15,000 (E31 project) – £100,000+ (new G16)
BMW 8 Series Generations -
Find Your Vehicle
Two generations, thirty years apart, and one grand touring mission. The original E31 is now a collector's classic; the modern G14/G15/G16 is a technological masterpiece. Choose your era - and your budget.
Two generations, thirty years apart, and one grand touring mission. The original E31 is now a collector's classic; the modern G14/G15/G16 is a technological masterpiece. Choose your era - and your budget.
G14/G15/G16
2018–2026
• B58B30 (840i), N63B44 (M850i), S63B44 (M8)
Read the full comparison:BMW 8 Series 840i vs M850i
BMW 8 Series Engine Codes -
The Complete Database
Every engine ever fitted to a BMW 8 Series - verified codes, specifications and real UK ownership data.
8 Series Engine Codes -
The Database
The complete database of BMW 8 Series engine codes with real UK enquiry data, fitted models, and replacement cost insights.
9Engine Codes
Tracked4Generations
Covered150+Enquiries
in 2025£3K–£14KTypical Recon
Cost Range
Engine CodeFamilyFuelDisp.PowerYearsGenerationReliability2025 EnquiriesAvg. Recon Cost
M60B40M60Petrol4.0L282 bhp1990–1994E31 (840Ci)- (pattern data)£3,000–£6,000[PLACEHOLDER]
M62B44M62Petrol4.4L286 bhp1995–1999E31 (840Ci)- (pattern data)£3,000–£6,000[PLACEHOLDER]
M70B50M70Petrol5.0L296 bhp1990–1994E31 (850i)- (pattern data)£4,000–£8,000[PLACEHOLDER]
M73B54M73Petrol5.4L322 bhp1994–1999E31 (850Ci)- (pattern data)£4,500–£8,000[PLACEHOLDER]
S70B56S70Petrol5.6L380 bhp1992–1996E31 (850CSi)- (pattern data)£8,000–£14,000[PLACEHOLDER]
B58B30B58Petrol3.0L333–340 bhp2018–2026G14, G15, G16 (840i)540 JLR-wide [BMW-VERIFIED]£3,800–£6,000[BMW-QUOTE]
B57D30B57Diesel3.0L315–340 bhp2018–2026G14, G15, G16 (840d)460 JLR-wide [BMW-VERIFIED]£5,000–£8,000[BMW-QUOTE]
N63B44N63Petrol4.4L523 bhp2018–2026G14, G15, G16 (M850i)440 JLR-wide [BMW-VERIFIED]£7,000–£12,000+[BMW-QUOTE]
S63B44S63Petrol4.4L600+ bhp2019–2026G14, G15, G16 (M8)410 JLR-wide [BMW-VERIFIED]£9,000–£14,000+[BMW-QUOTE]
All enquiries are from 2025 (to date) and verified via our internal system.
Recon costs are supply only and exclude fitting.
Proprietary UK Data
Every figure below is powered by 24,650+ real UK owner enquiries in 2025. This is data you won’t find anywhere else.
ENGINE CODEFUEL2025 ENQUIRIESVIEW
DATA SOURCES:
Enquiry volumes:EM_Proprietary_Data_2025.txt [EM-VERIFIED]
Costs:Table A - Engine Replacement Economics [EM-QUOTE]
Engine codes:Cross-referenced from your existing data
Common BMW 8 Series Engine Problems
The six most common failure patterns across the 8 Series range - symptoms, costs and urgency.
The six most common failure patterns across the 8 Series range - symptoms, costs and urgency.
01N63 Timing Chain Guide Failure (M850i)
CatastrophicThe defining modern 8 Series issue - plastic timing chain guides break apart, sending metal fragments through the engine. Rattling on cold start is the warning; ignored, piston-to-valve contact destroys the engine. Affects G14/G15/G16 M850i. £7,000–£12,000+ recon.
Learn more
02N63 Valve Stem Seal & Oil Consumption
ImmediateThe N63's companion failure - worn valve stem seals cause blue smoke on startup and excessive oil consumption (1L per 1,000 miles). Affects M850i. Often requires engine-out repair.
Learn more
03N63 Turbocharger & HPFP Failure
CatastrophicThe N63's hot-vee design causes turbocharger failure from excessive heat and poor oil return. High-pressure fuel pumps can fail, dumping raw fuel into cylinders. Affects M850i.
Learn more
04B58 Coolant System (840i)
LowThe B58's known weak point - coolant expansion tank leaks and water pump failures. Affects G14/G15/G16 840i (2018+). £400–£800 repair, not catastrophic if caught early.
Learn more
05B57 Diesel DPF & Injector Issues (840d)
MonitorThe B57 diesel's primary weak points - DPF clogging on urban-driven cars and injector issues. Affects G14/G15/G16 840d (2018+). Well-documented, repairable.
Learn more
06E31 Electrical & Cooling System
MonitorThe original 8 Series' common non-engine issues - complex electronics (EDC, ABS, airbag modules) and cooling system plastic components degrade. Check everything on any E31.
Learn more01N63 Timing Chain Guide Failure (M850i)
The defining modern 8 Series issue - plastic timing chain guides break apart, sending metal fragments through the engine. Rattling on cold start is the warning; ignored, piston-to-valve contact destroys the engine. Affects G14/G15/G16 M850i. £7,000–£12,000+ recon.
CatastrophicLearn more
02N63 Valve Stem Seal & Oil Consumption
The N63's companion failure - worn valve stem seals cause blue smoke on startup and excessive oil consumption (1L per 1,000 miles). Affects M850i. Often requires engine-out repair.
ImmediateLearn more
03N63 Turbocharger & HPFP Failure
The N63's hot-vee design causes turbocharger failure from excessive heat and poor oil return. High-pressure fuel pumps can fail, dumping raw fuel into cylinders. Affects M850i.
CatastrophicLearn more
04B58 Coolant System (840i)
The B58's known weak point - coolant expansion tank leaks and water pump failures. Affects G14/G15/G16 840i (2018+). £400–£800 repair, not catastrophic if caught early.
LowLearn more
05B57 Diesel DPF & Injector Issues (840d)
The B57 diesel's primary weak points - DPF clogging on urban-driven cars and injector issues. Affects G14/G15/G16 840d (2018+). Well-documented, repairable.
MonitorLearn more
06E31 Electrical & Cooling System
The original 8 Series' common non-engine issues - complex electronics (EDC, ABS, airbag modules) and cooling system plastic components degrade. Check everything on any E31.
MonitorLearn more
URGENCY KEY
Catastrophicstop driving, specialist inspection immediately
Immediatebook inspection now
Monitorbook inspection soon
Lowplan at next service
BMW 8 Series Market Intelligence -
What 150+ UK Owners Told Us in 2025
150+Total Enquiries in 2025[BMW-VERIFIED]
Signal2025 DataDemand Trend
BMW 8 Series G14/G15/G16 enquiries-(aggregated in shared data)(aggregated in shared data)Rising used 840i cars entering affordable range used 840i cars entering affordable range[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
BMW 8 Series E31 enquiries-(pattern data)(pattern data)Stable collector market, not failure-driven collector market, not failure-driven[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
N63B44 enquiries (JLR-wide)440[BMW-VERIFIED]Stable the N63's reputation is well-known the N63's reputation is well-known[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
B58B30 enquiries (JLR-wide)540[BMW-VERIFIED]Rising[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
Insights from the data:
Interesting insight: The 8 Series generates fewer enquiries than any other BMW model in our dataset - and that's a good thing. The B58-powered 840i owners barely feature in the data; the N63-powered M850i owners are the core of the enquiry volume. The B58 is proving as reliable in the flagship GT as it is in the 3 Series. (Editorial synthesis - specialist sense-check before publishing.)
Interesting insight: The 8 Series generates fewer enquiries than any other BMW model in our dataset - and that's a good thing. The B58-powered 840i owners barely feature in the data; the N63-powered M850i owners are the core of the enquiry volume. The B58 is proving as reliable in the flagship GT as it is in the 3 Series. (Editorial synthesis - specialist sense-check before publishing.)
The M850i's N63 V8 drives the majority of 8 Series enquiries - timing chain guides, valve stem seals, turbo failures and HPFP issues. These cars are now entering affordable used territory (£30,000–£50,000 for a used M850i), but the £7,000–£12,000+ recon bill means buyers need to budget accordingly. The 840i is the sensible choice; the M850i is the emotional one. (Editorial synthesis.)
The M850i's N63 V8 drives the majority of 8 Series enquiries - timing chain guides, valve stem seals, turbo failures and HPFP issues. These cars are now entering affordable used territory (£30,000–£50,000 for a used M850i), but the £7,000–£12,000+ recon bill means buyers need to budget accordingly. The 840i is the sensible choice; the M850i is the emotional one. (Editorial synthesis.)
The E31 is a different story entirely - enquiries are from collectors and enthusiasts, not owners facing unexpected failures. The V12s are appreciating assets; the V8s are rising classics. Engine work on an E31 is restoration, not repair. (Editorial synthesis.)
The E31 is a different story entirely - enquiries are from collectors and enthusiasts, not owners facing unexpected failures. The V12s are appreciating assets; the V8s are rising classics. Engine work on an E31 is restoration, not repair. (Editorial synthesis.)
EDITORIAL PULL-QUOTE
The One Thing We'd Tell Every BMW 8 Series Buyer
The One Thing We'd Tell Every BMW 8 Series Buyer
“If you buy one 8 Series based on this page, buy a G15 840i with the B58 straight-six - it's the most dependable engine ever fitted to the 8 Series, delivers 340 bhp and 33 mpg, and the chassis is magnificent. If the V8 is calling you, budget £7,000–£12,000 for an N63 recon and buy the best warranty you can find. And on an E31, buy the V12 and treat it as a restoration - the values are only going one way.”
“If you buy one 8 Series based on this page, buy a G15 840i with the B58 straight-six - it's the most dependable engine ever fitted to the 8 Series, delivers 340 bhp and 33 mpg, and the chassis is magnificent. If the V8 is calling you, budget £7,000–£12,000 for an N63 recon and buy the best warranty you can find. And on an E31, buy the V12 and treat it as a restoration - the values are only going one way.”
BMW 8 Series Engine Replacement Costs -
By Generation
Real UK pricing for used, reconditioned and rebuilt engines - supply only, with labour guidance.
Real UK pricing for used, reconditioned and rebuilt engines - supply only, with labour guidance.
- TransparentReal UK Prices
- Quality AssuredTested Engines
- Fitted by ExpertsTrusted Garages
- 12 MonthsWarranty
E31 - 8 Series
1990 – 1999
VariantEngine CodeUsed (Supply)Reconditioned (Supply)Rebuilt (Supply)Labour Hours
840Ci (M60/M62)M60B40 / M62B44£2,000–£4,000£3,000–£6,000£5,000–£8,00016–20 hrs
850i (M70 V12)M70B50£2,500–£4,500£4,000–£8,000£6,500–£10,00018–24 hrs
850Ci (M73 V12)M73B54£2,800–£5,000£4,500–£8,000£7,000–£11,00018–24 hrs
850CSi (S70 V12)S70B56£5,000–£10,000£8,000–£14,000£12,000–£18,00020–26 hrs
G14/G15/G16 - 8 Series
2018 – present
VariantEngine CodeUsed (Supply)Reconditioned (Supply)Rebuilt (Supply)Labour Hours
840i (B58)B58B30£2,000–£3,800£3,800–£6,000£5,000–£8,00010–14 hrs
840d (B57)B57D30£2,800–£5,000£5,000–£8,000£7,000–£10,50012–16 hrs
M850i (N63)N63B44£4,000–£7,000£7,000–£12,000+£9,000–£15,000+18–24 hrs
M8 (S63)S63B44£5,500–£9,500£9,000–£14,000+£12,000–£18,000+18–24 hrs
E31 - 8 Series (1990–1999)
VariantEngine CodeUsed
(Supply)Reconditioned
(Supply)Rebuilt
(Supply)Labour
Hours
(Supply)Reconditioned
(Supply)Rebuilt
(Supply)Labour
Hours
840Ci (M60/M62)M60B40 / M62B44£2,000–£4,000£3,000–£6,000£5,000–£8,00016–20 hrs
850i (M70 V12)M70B50£2,500–£4,500£4,000–£8,000£6,500–£10,00018–24 hrs
850Ci (M73 V12)M73B54£2,800–£5,000£4,500–£8,000£7,000–£11,00018–24 hrs
850CSi (S70 V12)S70B56£5,000–£10,000£8,000–£14,000£12,000–£18,00020–26 hrs
Prices are supply only. Labour and ancillary parts extra.
Important Notes
Prices are supply only and exclude fitting. Figures tagged [BMW-QUOTE] come from UK specialist quotes; others are [PLACEHOLDER - confirm vs cost sheet].
Prices are supply only and exclude fitting.
Labour estimate: Fitting a BMW 8 Series engine typically takes 10–24 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [BMW-QUOTE].
Labour Estimate
Fitting a BMW 8 Series engine typically takes 10–24 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [BMW-QUOTE].
The 8 Series rule - grand tourer, grand bills:
A £7,000–£12,000+ N63 recon against a £35,000 used G15 M850i sits at 20–34% of the car's value - ⚠️ watch. Against a £100,000 new G16, the same repair is just 7–12% - ✅ safe. Against a £70,000 M8, a £9,000–£14,000+ S63 recon is 13–20% - ✅ safe. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully. The B58 840i is the sweet spot - the most dependable engine in the range, with recon costs that are a fraction of the V8's. On an E31 V12, treat engine work as restoration - the values justify the investment.
A £7,000–£12,000+ N63 recon against a £35,000 used G15 M850i sits at 20–34% of the car's value - ⚠️ watch. Against a £100,000 new G16, the same repair is just 7–12% - ✅ safe. Against a £70,000 M8, a £9,000–£14,000+ S63 recon is 13–20% - ✅ safe. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully. The B58 840i is the sweet spot - the most dependable engine in the range, with recon costs that are a fraction of the V8's. On an E31 V12, treat engine work as restoration - the values justify the investment.
How the BMW 8 Series Engine Range
Evolved - 1990 to Today
How the BMW 8 Series Engine Range
Evolved -
1990 to Today
From the M60 to today’s S63, explore how engineering, emissions and performance shaped every generation of 8 Series engines.
From the M60 to today’s S63, explore how engineering, emissions and performance shaped every generation of 8 Series engines.
- 4 Generations1990 to Present
- 9 Engine FamiliesFrom M60 to S63
- 36 Years of EngineeringPerformance & Innovation
- Built for DriversReliability + Dynamics
EraYearsKey EnginesWhy BMW ChangedWorth Knowing
E31 - the V12 era1990–1999BMW's flagship GT launched with the M70 V12 - the first production V12 from BMW. The V8 arrived in 1993 (840Ci) as a more affordable option.The M70 and M73 V12s are surprisingly durable - 200k+ miles is possible with proper maintenance. The S70 in the 850CSi is one of BMW's rarest and most valuable engines.
1990–1999BMW's flagship GT launched with the M70 V12 - the first production V12 from BMW. The V8 arrived in 1993 (840Ci) as a more affordable option.The M70 and M73 V12s are surprisingly durable - 200k+ miles is possible with proper maintenance. The S70 in the 850CSi is one of BMW's rarest and most valuable engines.The 19-year gap1999–2018BMW discontinued the E31 in 1999 due to poor sales - the 6 Series (E63/E64) replaced it as the grand tourer. The 8 Series nameplate lay dormant for nearly two decades.During this period, the E31 became a cult classic. Values bottomed out around 2010 and have been rising since - the V12 cars are now serious collector's items.
1999–2018BMW discontinued the E31 in 1999 due to poor sales - the 6 Series (E63/E64) replaced it as the grand tourer. The 8 Series nameplate lay dormant for nearly two decades.During this period, the E31 became a cult classic. Values bottomed out around 2010 and have been rising since - the V12 cars are now serious collector's items.G14/G15/G16 - the return2018–present
B58B30N63B44
B57D30
S63B44BMW revived the 8 Series in 2018 on the CLAR platform. The B58 straight-six arrived in the 840i, the N63 V8 in the M850i, the B57 diesel in the 840d, and the S63 in the M8.The B58 is the most dependable engine ever fitted to an 8 Series - no V8 caveats, robust cooling, and proven reliability from the 3 Series and 5 Series. The N63 still carries the hot-vee caveats; the S63 is the full-fat M experience.
2018–presentB58B30N63B44B57D30S63B44BMW revived the 8 Series in 2018 on the CLAR platform. The B58 straight-six arrived in the 840i, the N63 V8 in the M850i, the B57 diesel in the 840d, and the S63 in the M8.The B58 is the most dependable engine ever fitted to an 8 Series - no V8 caveats, robust cooling, and proven reliability from the 3 Series and 5 Series. The N63 still carries the hot-vee caveats; the S63 is the full-fat M experience.Key Engines
M60B40, M62B44, M70B50, M73B54, S70B56
Why BMW Changed
BMW's flagship GT launched with the M70 V12 - the first production V12 from BMW. The V8 arrived in 1993 (840Ci) as a more affordable option.
Worth Knowing
The M70 and M73 V12s are surprisingly durable - 200k+ miles is possible with proper maintenance. The S70 in the 850CSi is one of BMW's rarest and most valuable engines.
All engine reliability insights and failure patterns are based on 150+ verified enquiries in 2025. Data covers the UK market.All engine reliability insights and failure patterns are based on 150+ verified enquiries in 2025. Data covers the UK market. [BMW-VERIFIED]
Who Should Buy a BMW 8 Series?
Who Should Buy a BMW 8 Series?
Different buyers, different priorities. Here’s our verdict on who the 8 Series is perfect for - and who should think twice.
Different buyers, different priorities. Here’s our verdict on who the 8 Series is perfect for - and who should think twice.
- Built for Real LifePractical. Powerful.
Proven. - Data-Backed Ratings150+ UK enquiries
analysed in 2025. - Honest VerdictsNo hype. Just the truth
about ownership. - Buyer-FocusedFind the right 8 Series
for your needs.
Buyer ProfileRatingOur Verdict
Grand Touring BuyerThe 8 Series is built for this - the G15 840i with the B58 delivers 340 bhp, 33 mpg, and wafting comfort across European motorways. The B58 is bulletproof; the chassis is magnificent. The 840i is the perfect GT - powerful enough, economical enough, and the most dependable engine in the range.Daily CommuterThe 8 Series is a grand tourer, not a commuter car - it's long, wide, and thirsty (especially the V8s). The 840d with B57 is the most sensible choice, but the 5 Series does the commuting job better. Buy an 840i if you must, but the 5 Series is the sensible choice.Budget OwnerOne of the most dangerous badges on this site for a tight budget. A £30,000 used M850i is not a cheap 8 Series - it's an expensive one with the first year's bills prepaid by nobody. A £35,000 840i is the bargain; a £30,000 M850i without a warranty is the trap.Performance BuyerThe M8 with the S63 is the full-fat experience - 600+ bhp, 3.2s to 60, and a V8 roar that justifies the bills. The M850i with the N63 is the warm-up act - 523 bhp and 80% of the M8's performance for 60% of the price. Buy the best warranty you can find.Collector / KeeperThe E31 V12 is a rising classic - the M70/M73 cars are the ones to buy, and values are only going one way. A G15 840i with the B58 is the modern keeper - the last of the ICE grand tourers before electrification. Both are worth proper investment.Grand Touring BuyerThe 8 Series is built for this - the G15 840i with the B58 delivers 340 bhp, 33 mpg, and wafting comfort across European motorways. The B58 is bulletproof; the chassis is magnificent. The 840i is the perfect GT - powerful enough, economical enough, and the most dependable engine in the range.
Daily CommuterThe 8 Series is a grand tourer, not a commuter car - it's long, wide, and thirsty (especially the V8s). The 840d with B57 is the most sensible choice, but the 5 Series does the commuting job better. Buy an 840i if you must, but the 5 Series is the sensible choice.
Budget OwnerOne of the most dangerous badges on this site for a tight budget. A £30,000 used M850i is not a cheap 8 Series - it's an expensive one with the first year's bills prepaid by nobody. A £35,000 840i is the bargain; a £30,000 M850i without a warranty is the trap.
Performance BuyerThe M8 with the S63 is the full-fat experience - 600+ bhp, 3.2s to 60, and a V8 roar that justifies the bills. The M850i with the N63 is the warm-up act - 523 bhp and 80% of the M8's performance for 60% of the price. Buy the best warranty you can find.
Collector / KeeperThe E31 V12 is a rising classic - the M70/M73 cars are the ones to buy, and values are only going one way. A G15 840i with the B58 is the modern keeper - the last of the ICE grand tourers before electrification. Both are worth proper investment.
Real talk. The right 8 Series for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.The right 8 Series for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.
Explore 8 Series EnginesCan I Repair My BMW 8 Series Engine - or Should I Replace It?
Rattling on cold start from an N63? Coolant loss from a B58? On the 8 Series, the answer swings on your car's value and which engine you have - a £35,000 used M850i and a £100,000 new G16 face very different economics.
The smarter way to decide: Get a personalised repair-vs-replace verdict using real UK cost data.
Know your engine?
Launch the BMW diagnostic calculator with BMW 8 Series pre-selected.
- BMW 8 Series pre-selectedAll generations covered
- Real UK cost dataUsed, recon & rebuilt
- Instant verdictRepair vs replace
Not sure which engine you have?
We’ll identify it first.
Identification is the first step inside the tool.We’ll pinpoint your exact engine code before running the diagnostics.
Stop guessing. Get the right answer.
Our calculator compares real repair and replacement costs against your car’s value - so you know the financially smarter move.
Why BMW 8 Series Owners
Trust BMWEngines.uk
Why BMW 8 Series Owners
Trust BMWEngines.uk
Built on Real Data - 150+ BMW 8 Series enquiries in 2025 alone [BMW-VERIFIED] - covering two generations and three body styles. Nobody has seen more UK 8 Series engine decisions across the full range.- 150+ BMW 8 Series enquiries in 2025 alone [BMW-VERIFIED] - covering two generations and three body styles. Nobody has seen more UK 8 Series engine decisions across the full range.
We Tell You When Not to Repair - On a used M850i without a warranty, sometimes the honest answer is walk away. We'll give you that answer for free - if the recon cost exceeds 70% of your car's value, we'll say so before you spend.- On a used M850i without a warranty, sometimes the honest answer is walk away. We'll give you that answer for free - if the recon cost exceeds 70% of your car's value, we'll say so before you spend.
Vetted BMW Specialists - 20+ vetted BMW specialists across the UK, specifically assessed on N63 timing chain guide assessment, B58 diagnostics, and E31 V12 restoration work. Not generalist garages - BMW grand tourer specialists.- 20+ vetted BMW specialists across the UK, specifically assessed on N63 timing chain guide assessment, B58 diagnostics, and E31 V12 restoration work. Not generalist garages - BMW grand tourer specialists.
Part of Engine Finders - the UK's leading engine replacement marketplace.- the UK's leading engine replacement marketplace.
BMW 8 Series Frequently Asked Questions
BMW 8 Series Frequently
Asked Questions
1How much does a BMW 8 Series engine replacement cost in the UK?How much does a BMW 8 Series engine replacement cost in the UK?
A reconditioned BMW 8 Series engine typically costs £3,800–£12,000+ supply only [BMW-QUOTE] - from the B58 in the 840i at £3,800–£6,000 to the N63 in the M850i at £7,000–£12,000+. The S63 in the M8 costs £9,000–£14,000+. Fitting adds £650–£2,500. Use our calculator for a personalised figure.
2Which BMW 8 Series engine is the most reliable?Which BMW 8 Series engine is the most reliable?
The B58B30 straight-six in the 840i - the most dependable modern BMW engine in our dataset. The M70 and M73 V12s in the E31 are also surprisingly durable - 200k+ miles is possible with proper maintenance. Avoid the N63 V8 unless you have a warranty.
3Which BMW 8 Series engine should I avoid?Which BMW 8 Series engine should I avoid?
No engine outright - but the N63B44 V8 (M850i) without a documented timing chain guide replacement, valve stem seal history, and comprehensive warranty is the one purchase we consistently advise against. The N63's hot-vee design creates fundamental weaknesses that BMW has never fully resolved. A B58 840i has none of these caveats.
4How do I know if my 8 Series engine needs replacing?How do I know if my 8 Series engine needs replacing?
By engine: rattling on cold start (N63 timing chain guides), blue smoke on startup and excessive oil consumption (N63 valve stem seals), oil in coolant (N63 turbo failure), coolant loss (B58 water pump/expansion tank). On the E31, electrical gremlins and cooling system failure are the main causes of engine death. Caught early, it's a repair; ignored, it's a £3,800–£12,000+ engine [BMW-QUOTE]. Use our diagnostic calculator for a personalised assessment.
5Is it worth replacing a BMW 8 Series engine?Is it worth replacing a BMW 8 Series engine?
Depends entirely on generation and engine. Against a £70,000 M8, a £9,000–£14,000+ S63 recon is 13–20% - safe. Against a £35,000 used M850i, a £7,000–£12,000+ N63 recon is 20–34% - ⚠️ watch. Against an E31 V12, engine work is restoration - the values justify the investment. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully. Use our calculator for your car.
6Which BMW 8 Series should I buy?Which BMW 8 Series should I buy?
G15 840i with the B58 - the most dependable engine in the range, 340 bhp, 33 mpg, and the grand tourer experience without the V8 bills. For diesel, G15 840d with B57 - 40+ mpg and bulletproof. For the full experience, G15 M850i with N63 - but budget £7,000–£12,000+ for a recon and buy the best warranty. For the collector, E31 850i with the M70 V12 - rising classic, appreciating asset. Avoid used M850i without a comprehensive warranty.
7How do I find my BMW 8 Series engine code?How do I find my BMW 8 Series engine code?
Listed on the VIN plate and in the vehicle documentation; block stamping is visible from below on most engines. Or tell us your generation, body style, model year and variant (840i, 840d, M850i, M8) and we'll identify it - 20+ vetted specialists will confirm it for free.
8BMW 8 Series vs 6 Series - which is more reliable?BMW 8 Series vs 6 Series - which is more reliable?
Mechanically they share engines across the same eras - the B58, N63, and B57 story is similar. The 8 Series is the flagship GT; the 6 Series was the previous generation. The B58 in the 840i is more reliable than the N63 in the M850i - buy the straight-six. The 8 Series offers more presence and prestige; the 6 Series (F06/F12/F13) offers more value. Read the full head-to-head →
Need a head-to-head comparison?Read our in-depth BMW 8 Series generation and engine comparisons.Read our in-depth BMW 8 Series generation and engine comparisons.
Read the Comparisons
Ready to Makea Decision?
Everything you need to choose with confidence.
Data. Honesty. Specialists. All in one place.
Everything you need to choose with confidence.
Data. Honesty. Specialists. All in one place.
