Hi Simon et al,Mandrake wrote:Hi Paul,
I know what you mean, once you've enjoyed that crash free smooth ride its very hard to go back to it being poor again, which makes chasing intermittent harsh ride very frustrating indeed! I chased it for four years on my previous Xantia and made a lot of improvement but never nailed it like I have on this car.
If you're still seeing bubbles in the top of the tank there's definitely still air getting in somewhere. Since the modification I see no bubbles on the surface of the tank at all, its like the surface of a lake on a calm day now. There are a few bubbles within the top of the return filter but none escape outside the filter and none seem to get sucked down into the pump filter inlet based on the ride remaining good.
As for the pump, there's no repair kit as such, however all but two of the seals (9 seals) are available from Citroen for a total of about £15. The following diagram shows where leaks can occur on the HP pump:
The most common place to leak is the upper location 1 on the diagram, this is the large hex bolt that has a steel high pressure pipe going into the middle of it. There is a second one 120 degrees away which is a bolt head without a pipe going into it. These two are the caps for the two pistons that drive the suspension and brakes, they have a black o-ring down inside and its very common for them to leak.
My pump started leaking out of the blue a month or so ago, enough that the alternator was getting a good LHM bath, those two o-rings were both leaking, they were both damaged with shards peeling off the o-rings. Fitting a new set of o-rings has cured the leak. Replacing those two o-rings is easy, especially if you have the pump off the car in a large vice.
There are 6 smaller green o-rings for the power steering pistons, the caps for those are torx head drive, (lower location 1 on the diagram above) they seem to be impossible to undo without a rattle gun, but fortunately they never seem to leak either.
I've tried and failed on both this Xantia and my previous one to get those torx caps undone with a normal socket wrench and I couldn't do it without risking striping the heads or damaging the pump so they must be really tight. (Personally I'd leave those torx head ones alone unless there is evidence of them leaking, still buy the seals, but only fit if needed)
Location 2 in the diagram is a large o-ring that seals the power steering output cup, that seal is available from Citroen and fairly easy to change. Watch out if you replace this one as there is a very thin almost invisible fibre washer between the centre and end cap on the pump - if its broken then you'll need to scrape all of it off so the face seals. It seems to seal ok with just the o-ring and the faces being clean.
Seal number 4 on the diagram can occasionally leak but can't be replaced without pressing the pulley off the shaft, and isn't available from Citroen, so you'd need to get an engineering shop to do that one if its leaking unless you have a press and are good at that sort of thing.
Seal number 5 on the diagram can leak, its not available from Citroen however I have found that it can be replaced with a square section sphere neck seal perfectly well - the diameter is not quite right but the thickness is perfect and my previous Xantia ran for four years with that type of seal fitted with no leaks.
Here's a couple of pictures of the HP pump from my previous Xantia (2 litre petrol) partially stripped down:
You can see the sphere neck seal sitting in the groove on the triangular plate.
When I replaced the seals on the pump a month or so ago to fix the leak I noticed a definite improvement in ride quality and consistency, the ride was far more intermittent and changeable before that. Whether it was one of the pump seals leaking causing it or whether I just got a better air tight seal on the low pressure inlet hose at the pump end when I reconnected it I can't be sure.
Following that up with the pipe modification in the tank seems to have got it to the point where I'm not getting any air drawn into the suspension at all.
Just saw this very interesting old thread while looking for info on the hp pump wear-related problems and repairs on it (mine has started leaking as well). I was just wondering; you have only mentioned the o-rings here. Are there any other internal components e.g. pistons, bearings etc that ought to be replaced as well as a part of the overhaul. My thinking is once it's gotten to the point where the o-rings start failing, other parts probably will follow suit soon thereafter. Asking as, about the same time the pump started leaking a high-pitched oscillating hissy noise has developed which seems to come from the general direction of the hydraulic pump -though without a car stethoscope I am just guessing, as it could be coming from the alternator, ac pump etc.
Thanks a lot in advance,
Gabriel