How much does a BMW 8 Series M850i engine replacement cost in the UK-

A BMW 8 Series M850i engine replacement typically costs £6,000-£10,000 for a reconditioned unit (supply only), rising to £8,000-£14,000 for a fully rebuilt engine with warranty. Dealer replacement costs can reach £14,000-£20,000 plus labour. Used N63TU2 engines: £3,500-£6,000 (higher risk, lower warranty). Reconditioned N63TU2 engines: £6,000-£10,000 (tested, partial warranty). Rebuilt N63TU2 engines: £8,000-£14,000 (fully overhauled, 12-month warranty).

Is it worth replacing the engine in a BMW 8 Series M850i-

Yes - with typical BMW 8 Series M850i values ranging from £25,000-£45,000 for 2018-2021 examples, a £6,000-£10,000 engine replacement represents just 20-40% of the car's value, making it financially viable. Vehicle value for M850i (2018-2021): £25,000-£45,000. Replacement cost: 20-40% of vehicle value (safe threshold). Dealer replacement cost: often exceeds specialist pricing significantly.

How long does a BMW 8 Series M850i engine replacement take-

A BMW 8 Series M850i engine replacement typically takes 12-16 hours of workshop labour for a specialist, with 16-22 hours at a main dealer due to hot-vee complexity. Specialist supply & fit: typically 3-5 working days. Dealer replacement: often 5-7 working days. Engine supply: nationwide delivery available, often next-day.

What's the difference between M850i and M8 Competition engines-

The BMW 8 Series M850i uses the N63TU2/N63B44T3 4.4L V8 producing 523-530hp, while the BMW M8 Competition uses the S63TU high-output 4.4L V8 producing 625hp - the same displacement but significantly different power output and calibration. M850i N63TU2: 523hp, twin-turbo V8, GT-focused tuning. M8 Competition S63TU: 625hp, higher boost, M-specific components. Engine codes are different - do not interchange without expert compatibility checks.

BMW M850i SPECIALISTS

BMW 8 Series M850i Engine Replacement Compare Prices & Get Quotes

Get quotes today from trusted UK BMW 8 Series M850i engine specialists. Compare prices on reconditioned, rebuilt and used engines for your BMW M850i xDrive - with supply and fit options available nationwide.

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BMW 8 Series M850i Engine

from£6,000 to £10,00...

Usedfrom £3,500
Reconditionedfrom £6,000
Common codesN63TU2, N63B44T3, S63TU

BMW 8-seriesUsed Engine — N63TU2

BMW 8-series M850i Reconditioned Engine — N63TU2

BMW 8-seriesReconditioned Engine — N63TU2

BMW 8-series M850i Rebuilt Engine — N63TU2

BMW 8-seriesRebuilt Engine — N63TU2

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How it works

3 Simple Steps to Finding the Right Replacement Engine

Clear information first, then the right engine and specialist for your exact vehicle.

Variant History

BMW 8 Series M850i Engine History & Specs at a Glance

The BMW M850i xDrive launched in 2018 as the performance petrol flagship of the revived G15 8 Series range, sitting above the 840i and below the M8 Competition. Throughout its production life, the M850i has been powered exclusively by BMW's hot-vee N63/S63 V8 family, with power outputs ranging from 523hp to 530hp across its lifecycle.

2018
BMW 8 Series M850i xDrive launches with N63TU2 (4.4-litre twin-turbo V8, 523hp)
2019
Gran Coupe (G16) M850i xDrive introduced, sharing the same N63TU2 engine
2020
Engine calibration updates across all M850i variants
2022
N63B44T3 designation appears in late production models
2024
LCI facelift retains N63TU2/N63B44T3 architecture

Every BMW 8 Series M850i engine code ever fitted in the UK is covered below, with UK rebuilt pricing and known failure points.

Engine Codes & Pricing

BMW 8 Series M850i Engine Codes Specifications & Replacement Cost

BMW N63B44):

N63TU2 — 4.4L Petrol V8 (2018-2024)

Power Output: 523hp
Years Fitted: 2018-2024

Can’t find your exact engine code?-> Get quotes for N63TU2 BMW 8 Series M850i engine replacement

-> Get quotes for N63TU2 BMW 8 Series M850i engine replacement

Common failure points and repair options

Valve Stem Seal Failure

Affected: BMW 8 Series M850i (N63TU2/N63B44T3, 2018-present)
Typical failure mileage: 60k-100k miles

Root cause

The hot-vee architecture places turbos inside the V of the engine, generating significant heat that degrades valve stem seals over time. This leads to oil consumption, blue smoke on start-up, and eventual catalytic converter contamination if left unaddressed.

Repair options

Repair tier	Dealer price	Specialist price
Valve stem seal replacement	£3,000-£6,000	£2,000-£4,000
Full Replacement - rebuilt engine	£14,000-£20,000+	£8,000-£14,000 (matches Section 4 N63TU2 rebuilt price)

Our recommendation

If caught early (before full engine damage), the specialist valve stem seal replacement is the more cost-effective choice for the BMW 8 Series M850i. However, once contamination has affected the turbos or catalytic converters, a full rebuilt engine with upgraded components and warranty is the safer long-term decision for a car of this value.

-> Compare rebuilt N63TU2 BMW 8 Series M850i engine prices

Timing Chain Tensioner Wear

Affected: BMW 8 Series M850i (N63TU2/N63B44T3/S63TU, 2018-present)
Typical failure mileage: 70k-120k miles

Root cause

The M850i's V8 uses a timing chain system that can suffer from tensioner wear over time. Chain stretch and tensioner failure manifest as a cold-start rattle and, if ignored, can cause catastrophic valve/piston interference.

Repair options

Repair tier	Dealer price	Specialist price
Timing chain and tensioner replacement	£2,500-£4,500	£1,500-£2,500
Full Replacement - rebuilt engine	£14,000-£20,000+	£8,000-£14,000 (matches Section 4 N63TU2 rebuilt price)

Our recommendation

For the BMW 8 Series M850i, timing chain tensioner wear is a preventable failure. If you hear cold-start rattle, have a specialist inspect it immediately. If caught early, the chain replacement is the sensible repair. If the chain has already slipped or snapped, full engine replacement with a warranty-backed rebuilt unit is the only safe route for a car of this calibre.

-> Compare rebuilt N63TU2 BMW 8 Series M850i engine prices

Cooling System Failures

Affected: BMW 8 Series M850i (N63TU2/N63B44T3, 2018-present)
Typical failure mileage: 60k-100k miles

Root cause

The hot-vee layout subjects turbo coolant lines and plastic fittings to extreme temperatures, causing premature degradation, leaks, and eventual overheating if not addressed.

Repair options

Repair tier	Dealer price	Specialist price
Coolant line replacement	£1,000-£1,800	£700-£1,200
Full system refresh with water pump	£1,800-£3,000	£1,200-£2,000

Our recommendation

Cooling system maintenance is essential on the BMW 8 Series M850i. Specialists recommend inspecting turbo coolant lines at every service from 60k miles. Proactive replacement of degrading components is far cheaper than repairing overheating damage.

-> Get BMW 8 Series M850i cooling system repair quotes

Don't Let Engine Failure Write Off Your BMW 8 Series M850i

The BMW 8 Series M850i's N63 V8 is a powerful but complex engine. Specialist rebuilt units include upgraded components addressing the original failure points, with a minimum 12-month unlimited-mileage warranty. Compare prices from our UK-wide network - supply and fit available nationwide, often at significantly less than dealer replacement costs.

Compare BMW 8 Series M850i Engine Replacement Prices Now ->

FAQ

BMW 8 Series M850i Engine ReplacementFrequently Asked Questions

Everything BMW 8 Series M850i owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

A BMW 8 Series M850i engine replacement typically costs £6,000-£10,000 for a reconditioned unit (supply only), rising to £8,000-£14,000 for a fully rebuilt engine with warranty. Dealer replacement costs can reach £14,000-£20,000 plus labour.

Used N63TU2 engines: £3,500-£6,000 (higher risk, lower warranty)
Reconditioned N63TU2 engines: £6,000-£10,000 (tested, partial warranty)
Rebuilt N63TU2 engines: £8,000-£14,000 (fully overhauled, 12-month warranty)

-> Get a personalised BMW 8 Series M850i engine quote now

Early warning signs of N63TU2 failure in the BMW 8 Series M850i include blue smoke on start-up (valve stem seals), cold-start rattle (timing chain tensioner), coolant loss (turbo coolant lines), and increased oil consumption.

Blue smoke after idle: valve stem seals degrading
Rattle on cold start: timing chain tensioner wear
Coolant warning: check turbo coolant lines and fittings

-> Compare M850i engine repair costs from specialists

Yes - with typical BMW 8 Series M850i values ranging from £25,000-£45,000 for 2018-2021 examples, a £6,000-£10,000 engine replacement represents just 20-40% of the car's value, making it financially viable.

Vehicle value for M850i (2018-2021): £25,000-£45,000
Replacement cost: 20-40% of vehicle value (safe threshold)
Dealer replacement cost: often exceeds specialist pricing significantly

-> Check current M850i engine replacement prices

The BMW 8 Series M850i uses the N63TU2/N63B44T3 4.4L V8 producing 523-530hp, while the BMW M8 Competition uses the S63TU high-output 4.4L V8 producing 625hp - the same displacement but significantly different power output and calibration.

M850i N63TU2: 523hp, twin-turbo V8, GT-focused tuning
M8 Competition S63TU: 625hp, higher boost, M-specific components
Engine codes are different - do not interchange without expert compatibility checks

-> Confirm your BMW 8 Series M850i engine code via registration

Why Choose Us

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BMW 8 Series M850i Engine Replacement Compare Prices & Get Quotes

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3 Simple Steps to Finding the Right Replacement Engine

BMW 8 Series M850i Engine History & Specs at a Glance

BMW 8 Series M850i Engine Codes Specifications & Replacement Cost

N63TU2 — 4.4L Petrol V8 (2018-2024)

BMW 8 Series M850i Engine Problems Repair Cost vs Replacement

Valve Stem Seal Failure

Timing Chain Tensioner Wear

Cooling System Failures

Don't Let Engine Failure Write Off Your BMW 8 Series M850i

BMW 8 Series M850i Engine ReplacementFrequently Asked Questions

Compare BMW 8 Series M850i Engine Prices Today