Xantia rear anti sink problem, help!
Moderator: RichardW
Xantia rear anti sink problem, help!
A short time ago RichardW advised and sumarised the problem of a Xantia rear end sinking at start up.I read the posts and concluded that the anti sink sphere was at fault I have same problem and changed the sphere yesterday.....guess what? it still sinks! The difference in this car is that it only sinks a small amount prior to the sphere change and after. Anyone help please?
It looks as though this might be the answer I have seen from a past post by Kowoslki??
When my '95 Xantia was sinking when the engine was started it wasn't the anti-sink sphere, it was the accumulator sphere that needed changing.
I'm not exactly sure why the car sinks when the accumulator is flat, my thinking goes as follows. When the engine starts, the hydraulic pump pressurises the hydraulic system normally this takes alittle time because the accumulator sphere needs to be pressurised, but when an accumulator is flat, it can't store very much pressure, so the hydraulic system pressurises very quickly. Once the system is pressurised enough, the anti-sink valves open, the rear height corrector is open (because even cars with anti-sink do sink albeit very slowly) there is no pressure available to raise the rear suspension, in fact the rear suspension has a higher pressure than the high pressure part of the hydraulic circuit, so the hydraulic fluid flows out of the rear suspension and the rear of the car falls.
'When a good accumulator sphere can hold pressure, it can use this pressure to pressurise various bits of the hydraulic system that need to be pressurised, e.g. anti-sink sphere, brake valve etc, so the car doesn't use its rear suspension pressure to pressurise the systems'.
When my '95 Xantia was sinking when the engine was started it wasn't the anti-sink sphere, it was the accumulator sphere that needed changing.
I'm not exactly sure why the car sinks when the accumulator is flat, my thinking goes as follows. When the engine starts, the hydraulic pump pressurises the hydraulic system normally this takes alittle time because the accumulator sphere needs to be pressurised, but when an accumulator is flat, it can't store very much pressure, so the hydraulic system pressurises very quickly. Once the system is pressurised enough, the anti-sink valves open, the rear height corrector is open (because even cars with anti-sink do sink albeit very slowly) there is no pressure available to raise the rear suspension, in fact the rear suspension has a higher pressure than the high pressure part of the hydraulic circuit, so the hydraulic fluid flows out of the rear suspension and the rear of the car falls.
'When a good accumulator sphere can hold pressure, it can use this pressure to pressurise various bits of the hydraulic system that need to be pressurised, e.g. anti-sink sphere, brake valve etc, so the car doesn't use its rear suspension pressure to pressurise the systems'.
John,
I have a similar problem, and the cause was the acumulator sphere (the one in the regulator).
When you start the engine, the pressure rise until the anti sink valve open. Once it opens, and due to a flat acumulator sphere there isn´t enough spare pressure to feed all the system that were open by the anti-sink valve, and because of that, the rear of the car goes down until the pump can create again the pressure.
In my case I only change the accumulator sphere and the problem was solved.
Regards
guillermo
I have a similar problem, and the cause was the acumulator sphere (the one in the regulator).
When you start the engine, the pressure rise until the anti sink valve open. Once it opens, and due to a flat acumulator sphere there isn´t enough spare pressure to feed all the system that were open by the anti-sink valve, and because of that, the rear of the car goes down until the pump can create again the pressure.
In my case I only change the accumulator sphere and the problem was solved.
Regards
guillermo