Also known as: n63b44, n63tu, 4.4 twin-turbo v8, 550i engine, x5 50i engine, 750i engine
BMW's 4.4 twin-turbo V8, and the engine that made the hot-vee layout ordinary: both turbochargers sit inside the V rather than outside it, which shortens the exhaust path and makes the car respond faster. It also traps a great deal of heat exactly where the valve gear lives, and most of this engine's reputation follows from that.
Oil consumption is the symptom that matters, and the valve stem seals are usually the cause. The seals sit at the top of each valve and keep oil in the head out of the combustion chamber; the heat of the hot vee hardens them early, and owners of the first cars report topping up by the quart. Do not read that as an engine that merely drinks oil — the same consumption starves the timing chain's tensioners, and a stretched chain on a V8 with the chain at the back is an engine-out job at best.
BMW's December 2014 recall covered timing chain stretch, fuel injectors, mass airflow sensors and crankcase vent lines on North American cars, and the 2012 technical update replaced the valve stem seals and revised the turbochargers — which is the clearest statement anyone has made about what the original ones did.
Which version matters more than the mileage. The original N63B44O0 is the one with the reputation; the N63TU of 2014 and the twin-scroll TU2 of 2016 progressively fixed it. Ask which the car has before reading anything into a service history.
Cars fitted with this engine
11 generations, across 1 make. From the authored catalogue — an absent car means the catalogue has not reached it, not that the engine was never fitted.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Posted about this engine
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about N63.