The brief
Jill brought her 320i in for normal servicing, and the specialist spotted a leak at the power steering reservoir, the tank that holds the hydraulic fluid for the steering. Caught early, sometimes all it takes is an O-ring. The reservoir sits on the power steering system, and where the hose or the level sensor passes through it there's an O-ring seal. Over the years that seal hardens and shrinks, so it stops sealing cleanly and a little fluid weeps out, runs down, and the level drops. A low power steering system can get noisy and the steering can go heavy if it's left, but caught at the weep stage it's a small job, just a fresh O-ring, the fluid topped and the system bled.
The diagnosis
A check confirmed it, the power steering reservoir was weeping from around its O-ring seal, not from a hose or the pump or the rack. The rest of the steering system checked out, it just needed the seal renewed before the fluid level dropped further. That's a simple fix: a fresh O-ring on the reservoir, the fluid topped to level, and the system bled of any air.
The work
The power steering reservoir was accessed, the old hardened O-ring removed and the seating cleaned, and a new genuine BMW-spec O-ring fitted, the reservoir refitted and the connections checked. The system was topped with the correct power steering fluid and bled of air by turning the steering lock to lock with the engine running. A road test confirmed the reservoir was dry, the level held, and the steering was light and quiet.
The outcome
No more fluid weep at the reservoir, the level holding, the steering light and quiet, and the system bled clean. The 320i went home with the leak sorted at the cheap end of the job. Caught at the weep stage it's a fresh O-ring; left to drop the fluid it's a noisy pump and heavy steering, so a quick fix headed that off.
