Thanks Jim! Maybe not a proper answer, just my own humble opinion.
The hydraulic system on the Citroen runs at a constant pressure of between 145 bar and 175 bar. The main principle of hydraulics is that you can compress a gas but not a fluid, the fluid being at high pressures and heat takes a bit of a pounding during it's life.
Over the years the hydraulic fluid will get old and oxidised, this is shown as a yellowing of the fluid, this in itself is not a problem and not dirty, just aged (like most of us) and it now needs to be changed, not flushed.
A very accurate check is to get yourself 2 x clean jars, put some new LHM in one (about 2" deep) and in the other put the same amount but out of your cars reservoir. Now stand the jars on some newspaper, you will be able to read the print through the new stuff, can you read it through yours? This will give you some degree of how mucky yours is.
There are 2 x reasons why I normally flush the system through.
1) When left for an age, the LHM will become very dirty or even contaminated so this is the time to flush the system
2) Before changing any hydraulic component, check the fluid and if in doubt change or flush, as it would be a shame to put a nice clean pump on a filthy system.
Hydraflush, or Hydra anything else, is designed to wash out the old dregs of fluid by mixing with it, then carrying it back to the reservoir, also it will scour the system and clean out the components such as height correctors and brake calipers.
To flush the system, (the way I do it, others may differ)
1) Fully depressurise into low position and open the pressure regulator bleed screw.
2) Using some hose and an old empty oil can, syphon as much fluid as you can from the reservoir.
3) Remove the nest of pipes from the reservoir top and retrieve the 2 x strainers.
4) Remove the reservoir.
5) Clean the reservoir, reservoir top and the strainers using parrafin, then dry off with some clean rags or blow with compressed air.
6) Put the lot back the way you found it.
7) Fill the system with flushing fluid (approx 4.5 litres)
8 ) Start the car and leave running for about 2 mins then tighten the bleed screw on the pressure regulator.
9) Lift the suspension up and down a few times, then leave on high and check/ top up fluid level.
10) Remove the wheels and bleed throgh the brakes, untill flushing fluid appears at each caliper.
11) Put the wheels back on and start up to check fluid level (top up)
Drive the car for about 2 x weeks, then do the whole job again bt this time instead of hydraflush, use LHM fluid.
Also it might be of some interest to know that I have used hydraflush to flush out "normal cars" power steering systems, with huge success.
Points to remember,
Use parrafin to clean the parts, it's cheaper than petrol, better than petrol and less volitial.
There is never any need to slacken the regulator bleed screw by more than 2 x turns.
Allways prop the car with stands when working under it.
Dont forget to double check the wheel bolts.
I dont think that I have left anything out, but please feel free to add any usefull tips.
This is the flushing fluid that I use.
Regards
Slim.
PS; I never put the smiley in where it should be No 8, I found it there on the preview and I cant seem to get rid of it !!!!!!!!!
I don't really want to ask our local Citroen dealers as I expect it'll cost the earth!
] will remove that contamination and more than likely hold it in suspension until it is drained in much the same was as a good engine oil does for engine contamination.
