Mine is doing my tits in !! Recently its got REALLY noisey !! The level of the fluid seems to be the same and not dropping BUT ontop of the cap and all over the underside of my bonnet is PAS fluid. I assume that the cap is a pressure cap that lets it out at a certain pressure ?? When i turned the steering wheel with the cap off i also got bubbles appearing which makes me believe there is air in the system replacing the fluid ?? Do i have a leak somewhere that is letting in air ? or is the pressure cap letting in the air when it expells the PAS fluid ?