O Learned Denizens,

I've finally pinned down the mystery steering fluid leak in my 540. It has been seeping out the back of the brake booster and into the passenger footwell.

I think what has happened is that I've been using the wrong fluid and the high level of fluid of circulation in the booster has given the wrong fluid the opportunity to attack the seals. I've recently replaced the steering box with a genuinely "remanufactured" one from ZF (as against the "reconditioning" I had done on the old one, which was worth naught. This was the point I realised I'd been using the wrong fluid (ie not CHF11) and so I'm expecting fall-out now the whole system has been flushed and bled. Next stop the self-levelling rear suspension, I'm sure!

The reason it's taken so long is that the ouside of the car (ie the bulkhead and floor) is completely dry, making me a bit baffled about finding the leak.

I should also clarify that my car is right hand drive and has a pantograph thingy for taking my pedal press across the car and into the back of the booster, which is in the same position whatever the drive hand of the car, hence my leak is into the passenger footwell and not the drivers.

So anyway, I plan on swapping the brake booster for a new one - unless someone knows of a seal kit I can get?

Final Q, if anyone's done this before and thinks there's something I should know before starting it, please let me know!

Thanks in advance,

Damian