Xantia HDI droping

[CitroenNuts]

Hi all
I have another problem with my 1999 HDI sx Xantia I replaced the front and rear spheres which did wonders for the ride also did the rear antisink sphere and I’m currently still running the Hydraflush. But things still don’t seem right the accumulator seems ok hardly ticks at all but say 50% of the time when I park the car and get out the front end drops about 1”3/4 and the car groans as it sinks this can’t be normal can it?

I was thinking it might be the pressure regulator but don’t want to replace such an expensive part without being sure is there any chance it could be the accumulator? Or is there anything else I may of overlooked

[Mandrake]

Hi all
I have another problem with my 1999 HDI sx Xantia I replaced the front and rear spheres which did wonders for the ride also did the rear antisink sphere and I’m currently still running the Hydraflush. But things still don’t seem right the accumulator seems ok hardly ticks at all but say 50% of the time when I park the car and get out the front end drops about 1”3/4 and the car groans as it sinks this can’t be normal can it?

Can you measure how long it takes between pressure regulator ticks when the car is idling ? (I find the easiest way to hear it click over the noise of the engine is with the bonnet closed and kneeling by the front of the car) Something more scientific than "hardly clicks at all" may give us a better idea.

Is it normal for it to drop a couple of inches after getting out ? Yep. You got out, which would have caused the car to go up a bit, so the height corrector makes a correction.

Is it normal for it to groan when doing this ? Not really. There are a couple of unrelated things can cause a groan - one is front struts that need lubricating (which only groan when they're visibly moving) and the other is the front anti-sink valve groaning. (Which can often carry on groaning many seconds after there is no visible movement - I've seen mine groan for up to 20 seconds before!)

I don't think anyone has conclusively proved the cause of this latter type of sustained groan, but in my opinion it is the front anti-sink valve chattering/oscillating when the height corrector tries to lower the car at the same time that the anti-sink valve is closing due to a lack of main system pressure from the accumulator.

The front anti-sink valve is located on the left side of the car under the hydraulic tank, so if the groan seems to be coming from the left, thats another clue that it could be that...yet another thing that would point to this being the cause is if it DOESNT groan if you get out of the car with the engine still idling...(struts that needed lubricating would still groan with the engine running)

If that is indeed the case, anything that would cause the main system pressure to fall away quickly before you get out of the car would cause this groaning behaviour at random. This could be a flat accumulator sphere, or an internal pressure leak in the system somewhere.

In my case the accumulator sphere was ok (nearly new) but I had a leaky front Hydractive electrovalve and I got a groan quite frequently when getting out of the car - probably 1 in 5 times. After replacing the electrovalve I don't think it's groaned once.

However your car being an SX won't have Hydractive 2 therefore wont have any electrovalves to leak, so a dud accumulator sphere is a better bet.

I was thinking it might be the pressure regulator but don’t want to replace such an expensive part without being sure is there any chance it could be the accumulator? Or is there anything else I may of overlooked

It's highly unlikely to be the pressure regulator - those things just go and go.... and I don't think a single case of this groaning effect has been linked to a pressure regulator problem. I'd be checking the regulator cycle time and accumulator sphere first...

Regards,
Simon

[CitroenNuts]

Sorry should have been more accurate about the ticking it seems to be about 10 to 15 seconds unless you do something to the height in which case it click till its settled as for the front anti sink call me silly but I had no idea it had one as I can’t find it the only other sphere at the front is the accumulator or at least it’s the only one I can find

[Mandrake]

Sorry should have been more accurate about the ticking it seems to be about 10 to 15 seconds unless you do something to the height in which case it click till its settled

Ok, well 10 to 15 seconds is much too often...a good accumulator sphere on a system that doesn't have any (unusual) leaks will give a regulator cycle time anywhere from a minute upwards. (Mine is about every 3 minutes since I fixed things) So I'd suggest replacing the accumulator sphere.

as for the front anti sink call me silly but I had no idea it had one as I can’t find it the only other sphere at the front is the accumulator or at least it’s the only one I can find

I did say the front anti-sink _valve_ There is no front anti-sink sphere. It's the valves (one front, one rear) which provide the anti-sink behaviour. The rear "anti-sink sphere" is mainly just a rear brake accumulator, although it can affect the efficiency of the anti-sinkvalve at the rear. (Long story....)

Regards,
Simon

[CitroenNuts]

I did say the front anti-sink _valve_ There is no front anti-sink sphere. It's the valves (one front, one rear) which provide the anti-sink behaviour. The rear "anti-sink sphere" is mainly just a rear brake accumulator, although it can affect the efficiency of the anti-sinkvalve at the rear. (Long story....)

Regards,
Simon

My fault didn't read fully

I was under the belief that the later model Xantia’s like mine had a small / poor pump so 10 > 15 sec interval on ticking would be normal? I assume thins is not the case and should maybe try a new Accumulator.

Well at least that will make a full set as it’s the only one I haven’t changed

[Mandrake]

I did say the front anti-sink _valve_ There is no front anti-sink sphere. It's the valves (one front, one rear) which provide the anti-sink behaviour. The rear "anti-sink sphere" is mainly just a rear brake accumulator, although it can affect the efficiency of the anti-sinkvalve at the rear. (Long story....)

Regards,
Simon

My fault didn't read fully

I was under the belief that the later model Xantia’s like mine had a small / poor pump so 10 > 15 sec interval on ticking would be normal? I assume thins is not the case and should maybe try a new Accumulator.

The very early Xantia's (1993) without anti-sink had a single output 6 piston pump with a 3.3cc/revolution output which was shared between steering/brakes/suspension.

Antisink models (1994 onwards) have a two output pump which is basically two pumps in one housing sharing a common pulley and a common inlet pipe. 6 pistons are devoted to the power steering and have about the same cc/rev output as the old style pump, but only 2 pistons are devoted to suspension/brakes, so roughly 1/3 of the pumping capacity is available for the main hydraulic system.

However the regulator ticking interval is not significantly related to the performance of the pump - its a measure of how quickly the pressure drops from 170 bars to 145 bars which is the pressure the regulator cuts in again. (It only takes about a second or two for the pump to pump it back up to 170 bars again, which is a very small percentage of the total regulator cycle time)

A flat accumulator sphere can't deliver much oil to anything in the hydraulic system which needs it without the pressure dropping suddenly, so a short regulator cycle time is either a flat accumulator sphere, an internal pressure leak somewhere in the system, or a combination of both...the accumulator sphere is by far the most common reason.

Well at least that will make a full set as it’s the only one I haven’t changed

The accumulator sphere often gets overlooked because it doesn't affect the ride but it's still important to the general operation of the hydraulic system, (it acts like the hydraulic version of a big filter capacitor on the output of a DC power supply) and it provides your emergency front braking if the pump stops working. (for example due to a snapped belt)

Regards,
Simon