Xantia- Anti-sink VALVE u/s?

Machra · Post by **Machra** » 19 Feb 2003, 14:38

My saga with hard suspension continues!!!!
Yesterday I replaced the accumulator sphere. Easy job and it's stopped the pump clicking every few seconds. It didn't cure the hard ride though so I thought I would give the suspension a workout to see if my hard ride was caused by air in the system. What I did notice was that when I lowered the car from the highest setting the front sunk quickly but the rear took its time. It did sink, with no juddering it just took about 30 seconds where the front sunk in 5 seconds. (Going from the lowest to the highest it raises level as it should) This made me wonder if the ant-sink VALVE was slow in releasing the pressure and it was this that is causing my hard ride. Anyone else had this problem. (It is not the height correctors that are at fault as the car would not raise and lower)
Edited by - Machra on 19 Feb 2003 09:42:06

alexx · Post by **alexx** » 19 Feb 2003, 15:26

I think it's to be expected that a car with anti-sink valves sinks slowly from highest position. Anti-sink valve works on pressure difference. In the normal position, pressure on one side of the slide valve is equal to pressure in accumulator (145-170 bar), and on other side it's equal to suspension working pressure (load dependant, but lower than in accumulator). In the highest position, pressure on both sides of slide valve is equal to pressure in accumulator. So, if hydaulic elements are in good order, it should take some time, until pressure on suspension side of the slide valve drops because of LHM leakage, mostly in hydraulic cylinders. So, your rear cylinders are obviously in better shape.
The ride is the same with new and flat accumulator sphere, because there are height correctors between accumulator and suspension spheres, which are closed most of the time. For the same reason, I don't think anti-sink valves can cause the 'hard ride'.