Xantia hydraulic failure - Help needed!

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
lhm_leak
Posts: 135
Joined: 21 Sep 2003, 02:33
Location: United Kingdom
My Cars:

Xantia hydraulic failure - Help needed!

Post by lhm_leak »

It's my own fault, really. I should have detoured to the nearest LHM stockist this morning when the STOP light came on, but I honestly thought the car would make it back home to my own supply!
There's been a small leak at the low pressure side of the pump for a few months now, so I'm losing some fluid anyway, and it's checked and topped up regularly. I can only guess that the leak's got worse recently, and I'm going to have to locate and fix it. That's not the immediate problem. This is.
During the drive home, I lost power steering. I'd half expected this to happen anyway, I'd had the same experience with a BX half a lifetime ago. I was expecting the suspension to go next, so I didn't get worried - until I touched the brakes and found I didn't have any... got a bit hairy, I can tell you. I worked out the explanation for myself, along with a few choice curses - oh well, at least I know my car's anti-sink system is working!
Very slowly drove to the nearest place to get some LHM. Filled the tank with about 3 litres of the stuff. The STOP light went out, and as I reversed out of the parking space I could feel the steering assistance was back. So were the main brakes.
Until I turned the wheel to go round the corner, that is. STOP light back on, no PAS. Brakes still working, but they too failed again after a while, suggesting that I was using residual pressure from the accumulator sphere.
Question - is this problem related to the possible need to prime the HP pump once it's run dry? I don't recall having to do this on my BX back in '86. And as for the rest of the system - will I have to bleed the brakes/steering? Any special procedures or gotchas?
Any advice will be gratefully received! Looks like I'm driving a Vauxhall tomorrow...[B)][:(][:(!][V]
Stu.
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

YES !
I'm definate it's prime time for the pump !
- and get that leak corrected NOW - it's much more a (dangerous) nuisance than any real complicated repair [}:)]
- no need to bleed anything else - as the LHM sitting in the lines to the brakes does not reverse - or get's shifted with air.
- may need the Citaerobics though :
http://citroenz.com/forum/viewtopic.php?t=42
Best of luck [;)]
lhm_leak
Posts: 135
Joined: 21 Sep 2003, 02:33
Location: United Kingdom
My Cars:

Post by lhm_leak »

Thanks Anders - I'm going to fix it properly at the weekend even if it's p***ing down with rain. I NEVER want to lose my main brakes again!!!
alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 15:53
Location: Australia
My Cars:
x 6

Post by alan s »

I wonder whether this one should be posted in a more appropriate spot like <b>common faults & fixes</b>.
It hadn't dawned on me that the anti-sink could create such a false sense of security so I wonder if it would be better placed in a smaller forum or list so that it could be more easily found by Xantia drivers?
Jon, Anders....your thoughts please.
Alan S
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Errhh - antisink valve AlanS ?
- don't you mean the safety valve ?
But both type valves will in fact close off when system pressure decreases below suspension pressure - preventing any further pressure drain by suspension.
The safety valve closes off when system pressure is below 100bar - whereas the antisink valves closes off directly on pressure difference.
Only leaks and front brakes then drains system pressure.
It's a general point that the safety valve can not protect against gross failure leaks - but protects against system faults or engine (pump) stall.
As for the power steering - it will allways be lost instantly - with a pump stall - or air in the pump.
RichardW
Forum Treasurer
Posts: 10812
Joined: 07 Aug 2002, 17:12
Location: United Kingdom
My Cars: MK2 '17 C4GP 1.6 BlueHDi 120
'13 3008 1.6 HDi GripControl
x 983

Post by RichardW »

Anders,
I think Alan is making the point that in an old style Cit if you have a gross loss of fluid the suspension will drop and give you good warning (by shaking your teeth out of your head!) that something is badly amiss. In an anti-sink car the main pressure drops, but then the anti-sink valves close meaning no loss of teeth, but every time you use the brakes you will exhaust the supply of pressure in the accumulator and the anti-sink sphere (which it isn't at all - it's a rear brake accumulator!). Once these are exhausted (possible quickly with old spheres with little pressure) you will be left with some suspension but no brakes, and more than likely brown undepants....
I think the secuity valve merely stops you dumping all the fluid out of a burst suspension line leaving you with no suspension, and without warning no brakes. Nice....
lhm_leak
Posts: 135
Joined: 21 Sep 2003, 02:33
Location: United Kingdom
My Cars:

Post by lhm_leak »

I'd agree with Alan about making this system behaviour somewhat better known - as I mentioned, having had a similar fault on a BX and had plenty of warning (and ultimately, no brake failure as it got fixed very quickly) it caught me very much by surprise - the anti sink system was the last thing on my mind. Fortunately for me, I discovered the lack of main brakes as I prepared to shed about 5mph to take a sharpish corner, and there was nothing else on the road at the time. The next Xantia driver with this problem might not be so lucky.
Overall, it simply highlights the need to keep the hydraulic system in good order and free from leaks, however small. I admit that my little incident was entirely of my own making - I really should know better, and can't believe my own stupidity. I should have fixed the leak ages ago, but "other things" kept cropping up. Well, "other things" can wait in the future, when I think about what *could* have happened...
Stu.
(Temporary Cavalier driver - Fixing Xantia at the weekend...)
alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 15:53
Location: Australia
My Cars:
x 6

Post by alan s »

Well, I checked the pencil line on the side of the bottle, re-read the posting & it said "at least I know my car's anti-sink system is working!" and yep, I did mean the anti-sink valve.....I'll go top my glass up now.[:D][:D][:D]
Alan S [;)][}:)]
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Seems I got things totally mixed up then [:I]
As for the present thread - Stewart in fact did wrote that AlanS [8D]
- but I ran out the route on the general workings of the systems.
I even totally missed your point AlanS - YES - I CERTAINLY do agree this advice/warning should have a sticky place somewhere - as it can be a very dangerous experience - that antisink Xantia owners assumes the system is all well - as long the suspension stays up.
I'll go rub OFF my GLASSSSes now [:D][:D][:D]
Post Reply