The brief
Eugene's X5 came in with an engine fault on the dash. An engine fault that turns out to be the oil pump is one of the serious ones, because the oil pump is what keeps oil pressure up to every bearing and moving part, and if it fails the engine runs short of oil and parts wear in a hurry. The X5's N55 engine relies on that pump to push oil round under pressure. When the pump fails, the pressure drops, and the bearings, the timing chain components and other parts that depend on a constant film of oil start to suffer. By the time the fault shows, the damage is usually done, so to bring the car back to full performance the engine has to come out, get stripped, and be rebuilt, a new oil pump fitted along with all the worn parts and a new timing chain set, everything reassembled to spec.
The diagnosis
The engine fault was diagnosed to an oil pump failure, with the loss of oil pressure having taken its toll on the engine internals. To restore the car's full performance, the engine needed an overhaul, not just a pump, the worn parts renewed and the engine rebuilt around a new oil pump. That's a full engine rebuild with a new oil pump and a new timing chain set, the worn internals renewed, rather than a pump alone on an engine that had been starved.
The work
The N55 engine was brought down out of the X5, the gearbox set aside, and the engine stripped to its components, every part cleaned and measured. A new genuine BMW-spec oil pump went in, the worn bearings, the timing chain and guides, the seals and gaskets all renewed with genuine BMW-spec parts, and the engine reassembled with every clearance and torque to the manual figures. It was refitted, the timing set, run in with fresh oil and a new filter, and the oil pressure checked good. A road test confirmed strong, smooth power, a clean idle, healthy oil pressure, and no warning lights.
The outcome
Strong, smooth power back, a clean idle, oil pressure where it should be on a fresh pump, and no engine fault on the dash. The X5 went home with the engine rebuilt and back to its full performance. An oil pump failure that's caught after the damage is done needs a proper rebuild, not a quick fix, so doing it once and right is what gets the car back to where it should be.
