First of all a big thanks to Paul for sending me a new regulator. I received it at lunchtime today and fitted after tea tonight. Prior to fitting the new regulator, the old one leaked fluid from around the plastic return housing. Every time the regulator unloaded there was a really hard thump which reverberated through the whole chassis. The regulator would cut in and out every 10 seconds when idling. As the regulator sphere was filling the pump would make a rrrrrrrrrrrRRRRRRRRRRoooP sound. With the new regulator in place the leak has stopped (saving me a small fortune in LHM which I was having to buy by the 45gallon drum). The regulator unloads almost silently. Whilst idle, the regulator clicks on and off every 5 min or so (which is astounding). When the regulator sphere is filling it makes a rrrrRRRRoop sound (much quicker than before).

I checked the sphere pressure (the old sphere previously fitted to the car) before fitting the new regulator to the car. It was 50Bar. The book says 60Bar, so I depressurised first and then filled it to about 65Bar on the gauge. I have no idea how accurate the gauge is.

A time interval of 5min between regulator cycles is incredible. It couldn't have been much more than that when it was new. In all my years of CX and XM ownership I've never known such a long time interval between regulator cycles.

Although I took it for a spin after fitting, it was dark by that time and I couldn't really tell if it was still sinking after pressing the brake pedal. I'll try it again tomorrow in the daytime.

It would therefore seem that the old regulator was faulty in a number of different ways. Clearly, it leaked. The very loud thump upon unloading was odd and clearly not correct. The frequent cycling meant that it was obviously leaking internally and passing back to the reservoir all the time. Time will tell if the sinking problem has been resolved. In any event, it was a very successful exercise and one for which it was worth noting the symptoms. The next time I see some of that behaviour from a regulator I thnk I'll be paying more attention to the regulator first rather than blaming other components and going on fishing expeditions.

Thanks for all the suggestions and thoughts. Much appreciated.

cheers
noz

Ahhh Nice One Noz..

Its amazing really how an external look belies how good or bad in some cases something is on the inside.

That regulator was off a 1995 M reg Xantia TD.. though looked scruffy externally, has prooved perfect inside. Inve no idea what the regulator sphere that was fitted was like, but I do know the regulator didn't tick a lot as I remmber the car it was fitted to...

Glad to have helped!

Regards
Paul

Uhh, so the regulator was not really new, but a replacement off an aging vehicle. Great that it worked/works.

I've asked my dealer to replace my HP regulator with a used one I got hold of and see how that affects my hydraulic idiosyncrasies (described elsewhere).
I was so proud of it being trouble free the first years I owned it


I've done the job on a BX, but access on the XM is even worse and I was much younger then. Without a lift it is a pain.