BMW 8 Series 840i Engine Replacement Compare Prices & Get Quotes

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

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

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

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

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

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