Used BMW 8 Series Timing Chain

All BMW 8 Series engines across both generations use a timing chain rather than a timing belt, so there is no scheduled belt replacement interval on this model. This applies to the petrols and diesels alike, including the M850i, 840i, 840d and M8 variants. A used timing chain from a breaker is a legitimate and common repair part for this car.

The current BMW 8 Series (G14 Cabriolet, G15 Coupé, G16 Gran Coupé) launched in 2018 and runs through to the present day as a single generation without a mid-cycle engine overhaul that would obviously break chain compatibility, but fitment really depends on sharing the exact same engine code rather than just the model year. Pull your engine code from the V5 or a VIN check and ask the breaker to match it precisely, as ancillary details and chain kit specifications can vary within a production run. Never assume year-to-year compatibility without confirming the engine code with the breaker against your registration.

The engine code matters far more than the year for a mechanical part like a timing chain. The 8 Series is offered with several engine variants — including inline-six petrol, inline-six diesel, and V8 petrol units — and each has its own chain configuration; a chain from a diesel 840d will not suit an M850i V8. Find your engine code on the V5 logbook or via a VIN check and give it to the breaker, as this single detail is more useful than the model year or badge.

M Sport is a trim and styling package, not a separate engine variant, so it does not affect which timing chain you need — fitment follows the engine code, not the trim badge. Two cars both wearing M Sport badging but fitted with different engines, such as the 840i and the M850i, will require different chains, purely because they are different engines. Where you should pay attention is the difference between a standard 8 Series and a full M8, as the M8 uses a distinct high-output version of the S63 V8 with its own specification.

No — the 840d uses a straight-six diesel engine (engine code B57) while the petrol 840i uses a straight-six petrol (B58), and these are entirely different engines with different timing chain assemblies that will not interchange. Even though the external appearance of the car is identical, the internal engine architecture is specific to each fuel type. Always confirm your engine code with the breaker so they can source a chain from the correct donor vehicle.

No — the original BMW 8 Series (E31, 1989–1999) and the current generation (G15, 2018–present) share only a nameplate and have no mechanical commonality whatsoever. The E31 used V8 and V12 engines of its era, while the G15 uses modern modular BMW engines, and the timing chains are completely different parts. Make sure any donor vehicle quoted by the breaker is from the correct generation for your car.