10 minute Xantia mod....what a difference!

[citroDane]

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.

Hi Simon et al,

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

[isisalar]

Simon is far more knowledgeable about these things than I and I'm sure he'll be along to share his wisdom.
If, like mine, yours is leaking LHM from the places marked 1 in the diagram, the repair is very easy to do in situ on the HDI as they are on top of the pump and the spring and ball stay in the cylinder when the plugs are removed. Doing this repair has eliminated the crashy ride completely so far. Mine was only leaking about 1 drop per week and this was making the LHM very frothy.
Cheers
Paul

[Mandrake]

An update on the ride quality of my car since this mod and a bit more fuel to add to the fire regarding the debate as to whether air bubbles being sucked into the pump can actually make the ride harsh or not...

The ride had been very good for a long time after this mod, however over about the last two months I'd noticed the ride very gradually start becoming quite harsh again, with no real improvement from normal citroerobics. I'd also started to notice the ride becoming quite "bouncy" and slightly unstable at speed where the car was in a constant state of reaction to road undulations.

Gradually worsening ride sneaks up on you, and I haven't had time to investigate, but it was really brought home when I visited David Hallworth a couple of weekends ago - his Activa was riding a lot better than my V6 ! To be fair the Activa had all new spheres and looks in top notch condition, the ride really was good - and super stable feeling at motorway speeds, while mine felt somewhat bouncy and unsettled on the same motorway even just going straight ahead...

We both agreed after driving mine that it really did feel like the spheres were getting a bit flat. (They've been on for a 1 1/2 years, so aren't new, but shouldn't be too bad yet)

While we were looking under the bonnet we also noticed a slight leak on the inlet feed hose for the pump that I hadn't noticed before. The V6 has an unusual arrangement with the feed hose from tank to HP pump where it has a stub hose at each end which is clamped onto a spigot on each end of the main length of hose... so there are two hose clamps at each end. See below for the pump end:



Just where the larger hose meets the smaller hose there was a slight weep - the junction between the two (just this side of the hose clamp in the photo) was wet with oil and with the engine running that little seam of oil was pulsating slightly, even though it wasn't leaking enough to drip. There must have been a gradual leak though as there was a bit of oil collected on the bottom of the A/C compressor. By all accounts a very minor but visible leak.

The hose clamp was already as tight as it could go so I really need to replace that stub of hose for a better fitting piece, but as the clamp was 10mm back from the end of the stub first I thought I'd try replacing the hose clamp with a new one and position the new one right close to the end of the stub, as depicted above.

Well that seems to have done the trick - for now at least, no visible leak whatsoever. I did this a few days ago and did some citroerobics and noticed some improvement in ride but it still wasn't as good as I remembered.

Gradually over the last few days the ride has improved all by itself (the car doesn't get driven much through the week, and it hasn't had citrerobics since the day when the hose clamp was changed) then last night and today it got a bit of a decent drive.

Today it suddenly dawned on me - the ride harshness was gone! Not just mostly gone, but 100% gone - no crashing or banging over potholes - completely silent when dropping into potholes apart from a slight pitter patter from the tyre tread, and the whole ride feels smooth and "cushioned". (That's the best I can describe it)

Furthermore that "unsettled" bouncy feeling at speed on undulating roads is completely gone, the car feels stable and sure footed at speed again, which it had not over the last few weeks. In fact I would say the ride is now better than it was when I first did this mod, which suggests there might have been a slight leak at the pump end all along which has gradually become worse.

So as far as I'm concerned this is yet more proof (as if it were needed) that air bubbles being pumped into the high pressure system - no matter their source - do indeed make the ride harsh and crashy, and when bad enough can also upset the rebound damping and stability of the car making it feel "unsettled" and bouncy at speed.

The ride was bad enough just a week ago that I thought some of the spheres were on their way out but today it feels absolutely fine!

While this "10 minute mod" seems to be very beneficial on some cars, what I've just described above shows that the feed hose to the pump being absolutely 100% air tight is also crucial. What looked like a very minor weep that wasn't even dripping was causing a major loss of ride quality.

So anyone contemplating this mod and/or trying to solve harsh ride check your feed hose very carefully for any possibility of slight leaks. Just because its not dribbling on the ground doesn't necessarily mean its sealed well enough to give a good ride!

[cc101]

Still a very interesting topic, I'm just about to strip down a spare pump and clean it, out of interest is the pully supposed to have any play in it!?

Cheers all.

[Mandrake]

By play do you mean end float or rocking movement ?

End float - yes a little bit, there is a shim inside to control end float from memory. Rocking motion - no.

[cc101]

Hi Si, in and out movement, there seems to be a fair bit! Just stripped down an FDV very interesting piece of engineering.

Cheers

[taffy]

cant wait to do this!

[cc101]

The mod does work on the majority, I had a spare untouched LHM tank and filter pod so swapped them over and the harshness returned so put my modded filter pod back in, and fine again!

[taffy]

good job! i drive my mates in my car and when u hit a nice bump and sail over it its so beautiful but when u hit a pothole or even slow down strips coming up to some junctions to make u aware of ur speed it feels like ur driving down a rocky road! lol i look at people in there porches and astons and still laugh and think i would have bought a c6

[taffy]

ok thats a bit silly..c6 car with a porche or aston engine is the compriise

[Mandrake]

The mod does work on the majority, I had a spare untouched LHM tank and filter pod so swapped them over and the harshness returned so put my modded filter pod back in, and fine again!

I've been out on the road again today and the ride is still perfectly crash and harshness free. Bliss. If it stays as good as it has been for the last two days I'll be very happy indeed.

Like you said in your very first post, I was literally finding myself looking for potholes to drive through, it's that good.

You can tell when the car is riding really well when even the sport mode setting on Hydractive 2 is not harsh - it looses the "floatiness" and becomes slightly firm and "fidgety" in sport mode as you would expect but it is not harsh in either mode, and a couple of times I found myself forgetting that I had put it in sport mode because the ride was still very good in that mode.

Check your HP pump feed hose for air leaks as well people! Belt and suspenders.

[cc101]

Glad to hear it Si sounds like you've got a goodun now. Question for you, just been under the rear end cleaning some mud off and noticed a fair bit of play in the dog bone, it won't pop off easily which is good but if you push the car up with your shoulder there's a fair amount of play in the bone knuckle before the corrector turrets start to move if you see what I mean? Should there be this play?

Cheers.

[Mandrake]

A new dog bone link doesn't have any play in it, but when they get old and worn they will have a bit of play. Eventually they'll wear to the point where they might pop off.

The play will increase the hysteresis of the height corrector - eg the difference in height between where it stops when its correcting up and correcting down will be greater the more slack there is in the mechanism so replacing the dog bone link may make the height corrections a little bit more accurate. (And reduce the chance of the link popping off in the future)

They're only a couple of quid from Citroen so worth replacing if you're concerned about it. I replaced the dog bone links on my previous Xantia but haven't done this one yet. It's also possible that some of the slack is from the ball rusting away, some people who have had problems with the link popping off have found the ball diameter had shrunk due to rust erosion!

There is supposed to be a felt washer between the dog bone and what it clips onto to keep dust and water out of the ball joint but you may find they're missing...(new dog bones don't seem to come with them either although any felt washer that fits would do)

[cc101]

Thanks Si, that explains why no matter how much I try to set it up perfect the normal ride height is always different between service high and service low! Will get two for each end!

Cheers.

[taffy]

is there a rebuild kit for the lhm hp pump then?