Power Steering Problem

[philipm]

I have a power steering problem on my 2002 Boxster S. It has simply stopped working. There were no undue noises or obvious fluid loss.

The first thing I did was to check the fluid level, it was not registering on the dipstick. It took less than 200ml to fill it up to the top (as I expected it to have airlocks and suck some on startup). On start up, nothing happened. Locking the steering a few times each way, I got one or two small bubbles, but nothing big enough to get a level drop.

I then took off the inside access plate to have a better look. Everything looks correct. The belt isn’t slipping and the pulley and inner shaft of the pump are rotating as I’d expect.

On taking the car for a drive with the covers on, but soundproofing removed, I could hear some light clicking noises when steering. I suspect this may just be the relief valve in the pump though. It doesn’t click at idle.

I can’t hear any exhaust/bypass noise or whine at full lock. Though in truth, I never noticed any when the steering was working fully.

The reservoir level does drop a couple of mm when the car is running and rises back a couple of mm when it’s off. I understand this is what should happen when the system pressurises. Is 2mm normal, or should it be more than this?

I’m somewhat at a loss as to what the fault is. Anything else I can check or do before taking it to a dealer?