Models · BMW
BMW 8 Series E31 buying guide
BMW's big V8 and V12 coupé of the 1990s, sold as the 850i, 850Ci, 840Ci and the Motorsport-developed 850CSi. Most of its known faults can be checked at the viewing, and a well-kept example rewards the care.
The versions
- 840Ci: 4.0 V8 (M60), 286PS, later replaced by the 4.4 V8 (M62) with the same power and more torque
- 850i and 850Ci: 5.0 V12 (M70), 300PS; a 5.4 V12 (M73) followed in other markets but wasn't officially sold in the UK
- 850CSi: 5.6 V12 (S70), 381PS, six-speed manual only, with active rear-wheel steering on European cars
- Six-speed manual, or four- and later five-speed automatics depending on engine and year
- 840Ci Sport from 1997, with lowered suspension and a deeper front spoiler
What to check on a E31 8 Series
3 model-specific things to look at when you view one. They're a starting point, not the full inspection.
V8 timing chain tensioner
What to look for: On a V8 car, ask whether the timing chain tensioner and guides have been replaced, and look for the invoice. It matters most on cars at or past 100,000 miles.
Why it matters: A worn tensioner lets the plastic chain guides wear, which can lead to engine damage. Specialists treat the tensioners as a job due at around 100,000 miles, so a car with it done is a sign of a car that's been looked after.
Smoke on start-up and on the move
What to look for: Watch the exhaust as the engine starts and when you lift off the throttle. On the drive, at about 30mph, accelerate hard and have someone watch for smoke behind the car.
Why it matters: On both the V8 and V12, smoke can come from a faulty inlet manifold pressure control valve, which can also cause an uneven idle, or from worn valves, stem seals or piston rings. The valve is a straightforward fix; worn rings on a V12 mean the engine has to come out.
An even note from the V12
What to look for: With the engine warm and the gearbox in neutral or park, press the throttle fully and lift off. The engine should rev and fall back evenly. An uneven or lumpy note is the thing to note.
Why it matters: A misfire or poor running on these engines often comes from ageing oxygen sensors or throttle bodies that need synchronising, and less often from low compression. If the V12 runs smoothly, specialists say there is little else to worry about.
Also in the full guide
- V12 oil leaks
- Cooling and heating
- Rear axle bushes and the CSi's rear steering
- Electrics, display and pop-up headlights
- The cold start, test drive and paperwork checks for the exact version you're viewing
The full guide to the E31 8 Series
The CrankSight guide walks you round the car on your phone at the viewing, with every check for the exact version you're looking at: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
£29 for the model, used on as many cars as you like, delivered within 72 hours or your money back.
Other generations
General points for the model, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with BMW.