BMW 6 Series 645Ci Engine ReplacementCompare Prices & Get Quotes
Get free, no-obligation quotes today from trusted UK BMW 6 Series 645Ci engine specialists. Compare prices on reconditioned, rebuilt and used N62B44A V8 engines for your E63 Coupé or E64 Convertible.
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From £3,500 to £6,000
Used from £2,000 · Reconditioned from £3,500 · Common codes: N62B44A
From £2,000
Tested, bare/short engine
From £3,500
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 6 Series 645Ci Replacement Engineto Finding the Best BMW 6 Series 645Ci Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW 6 Series 645Ci - Engine History & Specs at a Glance
The BMW 645Ci launched in 2003 as the flagship petrol V8 of the E63/E64 6 Series range, sitting above the 630Ci six-cylinder and below the later 650i V8 and M6 V10. It was powered exclusively by BMW's N62B44A 4.4-litre V8 throughout its production run.
Variant HistoryBMW 6 Series 645Ci - Engine History & Specs at a Glance
The BMW 645Ci launched in 2003 as the flagship petrol V8 of the E63/E64 6 Series range, sitting above the 630Ci six-cylinder and below the later 650i V8 and M6 V10. It was powered exclusively by BMW's N62B44A 4.4-litre V8 throughout its production run.
BMW 6 Series 645Ci
Fuel TypePetrol
Engine Size4.4L (4,398 cc)
Power Output333 hp (245 kW) @ 6,100 rpmEngine History Timeline
N62B44A 4.4-litre V8 petrol, 333 hp, launch of E63 Coupé (July 2003) and E64 Convertible
645Ci replaced by 650i (N62B48 4.8-litre V8 367 hp) - 645Ci production ends
Key Specs Snapshot
Fuel TypePetrolEngine Size4.4L (4,398 cc)Power Output333 hp (245 kW) @ 6,100 rpmTorque450 Nm @ 3,600 rpmYears Produced2003-2005Every engine fitted to the BMW 6 Series 645Ci is covered below, with UK rebuilt pricing and known failure points.
BMW 6 Series 645Ci Engine Codes - Specifications & Replacement CostBMW 6 Series 645Ci Engine Codes - Specifications & Replacement Cost
4.4L V8 Petrol (2003-2005)
Power Output333 hp (245 kW) @ 6,100 rpmTorque450 Nm @ 3,600 rpmYears Fitted2003-2005ChassisE63 (Coupé), E64 (Convertible)Displacement4,398 ccCompression Ratio10.0:1ValvetrainDOHC with Double-VANOS variable valve timing
Compatible Trim Levels
- 645Ci
- 645Ci SE
- 645Ci Sport
- 645Ci M Sport
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£2,000-£3,500
Reconditioned
Addressed known issues, tested
£3,500-£5,500
Rebuilt
Full teardown, upgraded internals
£5,000-£7,500
Common Failure
The N62B44A V8 is known for valve stem seal wear leading to excessive oil consumption and blue smoke from the exhaust, typically from 60,000 miles onwards. Timing chain guides can also become brittle and fail, producing a rattling noise from the front of the engine on cold starts. Cooling system components - particularly the electric water pump - are prone to failure without much warning.
The BMW 645Ci is powered exclusively by the N62B44A 4.4-litre V8 - a smooth, powerful engine that's now well into its second decade. While the N62 delivers a refined driving experience, it has several well-documented weak points that become increasingly expensive to manage as mileage climbs. Rebuilt N62B44A engines supplied through EnginesMarket include upgraded valve stem seals, timing chain components, and cooling system parts that address the original failure points, plus a minimum 12-month unlimited-mileage warranty.
Why the BMW 6 Series 645Ci N62B44A Burns Oil
Affected Vehicles
BMW 6 Series 645Ci (N62B44A, 2003-2005)
Typical Failure Mileage
60,000-100,000 miles
Root Cause
The valve stem seals harden and shrink over time, allowing oil to seep past into the combustion chamber. This leads to blue smoke on start-up, fouled spark plugs, and progressively worsening oil consumption.
Why It Happens
The valve stem seals harden and shrink over time, allowing oil to seep past into the combustion chamber. This leads to blue smoke on start-up, fouled spark plugs, and progressively worsening oil consumption.
Dealer (parts + labour)
£2,500-£4,000
Specialist (parts + labour)
£1,500-£2,800
What it involves
Replace all 32 valve stem seals (labour-intensive - cylinder heads remain on engine)
Suitability
Viable if the car is otherwise in good condition and oil consumption is the only issue
1 - 2 daysDealer (parts + labour)
£6,500-£9,500
Specialist (parts + labour)
£5,000-£7,500 (matches Section 4 rebuilt figure)
What it involves
Supply & fit, upgraded valve stem seals, timing chain components, water pump, and 12-month warranty
Suitability
Best for high-mileage engines with multiple concurrent failures
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 |
|---|---|---|---|---|---|
 Valve stem seal replacement Minor | £2,500-£4,000 | £1,500-£2,800 | Replace all 32 valve stem seals (labour-intensive - cylinder heads remain on engine) | Viable if the car is otherwise in good condition and oil consumption is the only issue | 1 - 2 days |
 Full Replacement - rebuilt/reconditioned engine Best Value | £6,500-£9,500 | £5,000-£7,500 (matches Section 4 rebuilt figure) | Supply & fit, upgraded valve stem seals, timing chain components, water pump, and 12-month warranty | Best for high-mileage engines with multiple concurrent failures | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical BMW 645Ci (2003-2005) in fair-to-good condition is worth approximately £4,000-£12,000 depending on mileage, condition, and whether it's a Coupé or Convertible [THIRD-PARTY - Auto Trader/Parkers market observation]. - Vehicle worth under ~£5,000: valve stem seal replacement or a used engine typically makes more sense than a full rebuilt unit. - Vehicle worth ~£5,000-£8,000: evaluate both; reconditioned is viable if keeping the car 2+ years. - Vehicle worth ~£8,000-£15,000: reconditioned/rebuilt usually justifies the premium via warranty and reliability. - Vehicle worth £15,000+: replacement cost is typically small relative to vehicle value.
Our Recommendation
Our Recommendation
If your 645Ci is burning oil but otherwise running well, have the valve stem seals replaced by a BMW specialist - it's a well-understood job and will restore the engine for many more miles. If the timing chain is rattling or the cooling system has failed, factor in the cumulative cost of repairs: once you're past £3,500 in specialist bills, a rebuilt engine with a warranty starts to look like the better value.
Don't Let Engine Failure Write Off Your BMW 6 Series 645Ci
The N62B44A is a fantastic V8 when properly maintained, but its known failure points - valve stem seals, timing chain guides, and the electric water pump - can turn expensive quickly. A rebuilt engine through EnginesMarket addresses all of these issues with upgraded components and comes with a 12-month unlimited-mileage warranty. Compare quotes from UK specialists today and keep your 645Ci on the road for years to come.
Compare rebuilt N62B44A BMW 6 Series 645Ci 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 6 Series 645Ci. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW 6 Series 645Ci Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW 645Ci engine replacement cost in the UK-
A replacement N62B44A engine for a BMW 645Ci typically costs £2,000-£3,500 for a used unit, £3,500-£5,500 for a reconditioned unit, and £5,000-£7,500 for a fully rebuilt engine with a 12-month warranty [EM-QUOTE via N63 proxy]. Supply and fit adds approximately £780-£1,040 in specialist labour (12-16 hours at £65/hr) [EM-QUOTE].
- Used engines: lowest cost, variable condition and mileage
- Reconditioned engines: restored to OEM tolerances, balanced cost and reliability
- Rebuilt engines: fully stripped and rebuilt with new components, best warranty
Question 2What are the signs of N62B44A valve stem seal failure in a 645Ci-
The most common sign is blue smoke from the exhaust on cold start or after idling, caused by oil seeping past worn valve stem seals into the combustion chamber. Other symptoms include:
- Increasing oil consumption between services (1 litre per 1,000 miles or more)
- Fouled spark plugs leading to misfires
- Failed MOT emissions tests due to excessive hydrocarbons
Question 3Is it worth replacing the engine in a BMW 645Ci-
It depends on the condition of the rest of the car. A typical 645Ci is worth £4,000-£12,000. If the body, interior, and transmission are in good condition, a rebuilt engine (£5,000-£7,500 fitted) can extend the car's life by 80,000+ miles and is often cheaper than buying a replacement 645Ci in similar condition. If the car has rust, suspension issues, or a failing gearbox, consider scrapping or breaking it instead.
- Check MOT history and bodywork before committing
- Low-mileage, well-maintained examples justify the investment
- Convertible values typically hold better than Coupé values
Question 4How long does a BMW 645Ci engine replacement take-
Most BMW 645Ci engine replacements take 2-4 days for supply and fit at a specialist garage. The N62B44A is a relatively straightforward V8 to remove and refit on the E63/E64 chassis, though the engine bay is tight. Allow additional time if the car requires:
- Cooling system components (water pump, thermostat, hoses)
- VANOS solenoid replacement
- Exhaust manifold or catalyst work
- Collection and delivery (1-2 days depending on location)
Question 5Do BMW 645Ci replacement engines come with a warranty-
Yes - all rebuilt and reconditioned BMW 645Ci engines supplied through EnginesMarket include a minimum 12-month unlimited-mileage warranty. Used engines typically have a 3-6 month warranty depending on the supplier. Extended warranty options are available with some specialists.
- Rebuilt engines: 12-24 month warranty, unlimited mileage
- Reconditioned engines: 12-month warranty, unlimited mileage
- Used engines: 3-6 month warranty, mileage-dependent
Question 6What's the difference between the 645Ci and 650i engine-
The 645Ci uses the N62B44A - a 4.4-litre V8 producing 333 hp. The 650i (which replaced the 645Ci in 2005) uses the N62B48 - a 4.8-litre V8 producing 367 hp. The engines share the same basic architecture and many components, but the 650i's larger displacement delivers more power and torque. A 645Ci engine cannot be directly replaced with a 650i engine without significant ECU and hardware changes.
- 645Ci: 4.4L, 333 hp, 450 Nm - produced 2003-2005
- 650i: 4.8L, 367 hp, 490 Nm - produced 2005-2010
- Engine swaps between the two are not recommended
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