BMW 8 Series 850CSi Engine ReplacementCompare Prices & Get Quotes
Need a BMW 8 Series 850CSi engine replacement- Get quotes today from trusted UK BMW 850CSi engine specialists. Compare prices on reconditioned, rebuilt and used engines for the rare S70B56 V12.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £12,000 to £18,000
Used from £5,000 · Reconditioned from £9,000 · Common codes: S70B56
From £5,000
Tested, bare/short engine
From £9,000
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 850CSi Replacement Engineto Finding the Best BMW 8 Series 850CSi Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW 8 Series 850CSi - Engine History & Specs at a Glance
The BMW 850CSi arrived in 1992 as the flagship of the E31 8 Series range, developed by BMW's M division. Its S70B56 V12 was a heavily reworked version of the M70 engine, bored and stroked to 5.6 litres with unique internals - making it one of the most desirable classic BMW engines ever produced.
Variant HistoryBMW 8 Series 850CSi - Engine History & Specs at a Glance
The BMW 850CSi arrived in 1992 as the flagship of the E31 8 Series range, developed by BMW's M division. Its S70B56 V12 was a heavily reworked version of the M70 engine, bored and stroked to 5.6 litres with unique internals - making it one of the most desirable classic BMW engines ever produced.
BMW 8 Series 850CSi
Fuel TypePetrol
Engine Size5.6L
Power Output375-380 bhp / 279 kWEngine History Timeline
E31 8 Series launched with M70B50 5.0-litre V12 (296 bhp)
1992 (September) - 850CSi introduced with S70B56 5.6-litre V12
1996 - 850CSi in production; only 1,510 built worldwide with just 138 UK right-hand drive examples
E31 production ends; no direct successor until the G15 8 Series in 2018
Key Specs Snapshot
Fuel TypePetrolEngine Size5.6LPower Output375-380 bhp / 279 kWYears Produced1992-1996Every engine fitted to the BMW 8 Series 850CSi is covered below, with UK rebuilt pricing and known failure points.
BMW 8 Series 850CSi Engine Codes - Specifications & Replacement CostBMW 8 Series 850CSi Engine Codes - Specifications & Replacement Cost
5.6L V12 Petrol (1992-1996)
Power Output375-380 bhp / 279 kWTorque406 lb-ft / 550 NmYears Fitted1992-1996TransmissionGetrag 560G 6-speed manual onlyFuel DeliveryBosch Motronic 1.7 with two independent DME ECUs (one per cylinder bank)Compression Ratio9.8:1Cylinder ConfigurationV12, 60-degree bank angle, 2 valves per cylinder
Compatible Trim Levels
- 850CSi (only)
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£5,000-£9,000 `[INDUSTRY ESTIMATE]`
Reconditioned
Addressed known issues, tested
£9,000-£14,000 `[INDUSTRY ESTIMATE]`
Rebuilt
Full teardown, upgraded internals
£12,000-£18,000 `[INDUSTRY ESTIMATE]`
Common Failure
The S70B56 is a robust engine when maintained, but age-related issues include cooling system degradation (water pumps, radiator hoses and expansion tanks), ignition system failures (coil packs and spark plugs), and vacuum leaks affecting idle and high-RPM performance. The dual-DME setup with two separate engine control units (one per cylinder bank) can also present diagnostic challenges as components age.
The S70B56 is one of BMW's most celebrated engines, but age takes its toll on every component. With the youngest 850CSi now approaching 30 years old, cooling systems, ignition components and rubber seals are the primary failure points. Rebuilt S70B56 engines through EnginesMarket include upgraded components addressing these age-related weaknesses, plus a minimum 12-month unlimited-mileage warranty.
Why the BMW 8 Series 850CSi S70B56 Needs Regular Coolant Attention
Affected Vehicles
BMW 8 Series 850CSi (S70B56, 1992-1996)
Typical Failure Mileage
60,000-100,000 miles (age-related)
Root Cause
The S70B56's cooling system uses plastic water pump impellers and ageing rubber hoses that become brittle over time. The V12's cramped engine bay (the S70 sits deep in the E31's engine compartment) makes cooling system access labour-intensive.
Why It Happens
The S70B56's cooling system uses plastic water pump impellers and ageing rubber hoses that become brittle over time. The V12's cramped engine bay (the S70 sits deep in the E31's engine compartment) makes cooling system access labour-intensive.
Dealer (parts + labour)
£1,500-£2,500
Specialist (parts + labour)
£800-£1,500
What it involves
Water pump, thermostat, hoses, expansion tank, coolant flush
Suitability
Recommended preventative maintenance every 60k miles or 8-10 years
1 - 2 daysDealer (parts + labour)
£18,000-£25,000
Specialist (parts + labour)
£12,000-£18,000
What it involves
Supply & fit, upgraded components addressing the original failure point, 12-month warranty
Suitability
When catastrophic failure occurs or comprehensive refresh is required
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 |
|---|---|---|---|---|---|
 Cooling system refresh Minor | £1,500-£2,500 | £800-£1,500 | Water pump, thermostat, hoses, expansion tank, coolant flush | Recommended preventative maintenance every 60k miles or 8-10 years | 1 - 2 days |
 Full Replacement - rebuilt/reconditioned engine Best Value | £18,000-£25,000 | £12,000-£18,000 | Supply & fit, upgraded components addressing the original failure point, 12-month warranty | When catastrophic failure occurs or comprehensive refresh is required | 1 - 2 days |
Our Recommendation
Our Recommendation
For the BMW 8 Series 850CSi, preventative maintenance is always the better value. A cooling system refresh or ignition service costs a fraction of a full engine replacement and can prevent catastrophic failure. However, if the S70B56 has suffered a timing chain failure, overheating damage, or internal mechanical failure, a rebuilt engine from a specialist - with documented provenance and warranty - is the sensible path. Given the 850CSi's collector value, investing in a proper rebuild preserves both the car's usability and its investment potential.
Don't Let Engine Failure Write Off Your BMW 8 Series 850CSi
The S70B56 is a masterpiece of 1990s engineering, but age-related failures are inevitable. A specialist rebuild through EnginesMarket gives you upgraded components, a 12-month warranty, and nationwide delivery - all at a fraction of main dealer prices. With only 138 UK right-hand drive examples ever built, your 850CSi is worth protecting.
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 850CSi. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW 8 Series 850CSi Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW 8 Series 850CSi engine replacement cost in the UK-
A full BMW 8 Series 850CSi engine replacement typically costs £12,000-£18,000 for a rebuilt S70B56 from a specialist, with used units from £5,000-£9,000. Fitting adds labour costs - the V12's tight engine bay means 18-24 hours of specialist labour is typical.
- Rebuilt S70B56: £12,000-£18,000 supply-only
- Reconditioned: £9,000-£14,000
- Used: £5,000-£9,000
Question 2What are the common signs of engine failure in a BMW 850CSi-
Common warning signs include overheating (cooling system failure), misfiring or hesitation at high RPM (ignition or DME issues), rough idle or cutting out, and unusual noises from the engine bay. Given the S70B56's age, regular specialist inspection is essential.
- Overheating: cooling system refresh required
- Misfires: coil packs, plugs, or DME diagnostics
- Rough idle: vacuum leaks or ignition issues
Question 3Is it worth replacing the engine in a BMW 850CSi-
Yes - with only 138 UK right-hand drive examples built, the 850CSi is a highly collectable modern classic. A £12,000-£18,000 rebuilt engine represents approximately 20-30% of the car's value, making replacement a sound investment for preserving both usability and value.
- 850CSi average value: ~£63,000
- Rebuilt engine cost: £12,000-£18,000
- Replacement is financially viable and value-preserving
Question 4How long does a BMW 850CSi engine replacement take-
A full BMW 8 Series 850CSi engine replacement typically takes 2-4 weeks, including sourcing the S70B56 unit, specialist fitting, and testing. The V12's complex installation and tight engine bay mean specialist workshops require significant time for proper installation.
- Sourcing: 3-10 days
- Fitting: 18-24 hours of labour
- Testing and commissioning: 2-5 days
Question 5What's the difference between the 850CSi and the 850i/850Ci engine-
The 850CSi uses the S70B56 - a 5.6-litre V12 producing 375 bhp. The 850i uses the M70B50 (5.0-litre, 296 bhp) and the 850Ci uses the M73B54 (5.4-litre, 322 bhp). The S70B56 features a forged crankshaft, redesigned pistons, higher compression (9.8:1), and unique engine management.
- 850CSi: S70B56 - 5.6L, 375 bhp, 6-speed manual only
- 850i: M70B50 - 5.0L, 296 bhp
- 850Ci: M73B54 - 5.4L, 322 bhp
Question 6Can I get a warranty on a rebuilt BMW 850CSi engine-
Yes - every rebuilt BMW 8 Series 850CSi engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty. Specialist rebuilds also include documentation of all work carried out, which is essential for maintaining the car's provenance and value.
- 12-month warranty minimum
- Unlimited mileage
- Full documentation included
Why Choose UsCompare BMW 8 Series 850CSiEngine PricesToday
150+ S70B56 enquiries handled through our network
12-Month Warranty on every rebuilt BMW 8 Series 850CSi engine
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Comparing BMW 8 Series 850CSi engine replacement quotes is free, no-obligation, and specific to your exact S70B56 V12. With only 138 UK right-hand drive examples ever built, getting the right specialist for your 850CSi matters. Enter your registration and get tailored quotes from trusted UK BMW 850CSi engine specialists today.
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