Xantia Era Rubber Tubing

addo · Post by **addo** » 19 Dec 2009, 03:55

I'm having a run of significant failures with the return lines. They are cracking, either just inside the heatshrink bands or near the plastic "tree" connections.

Several things occur to me. Firstly, poor pressure regulation, either due a to duff pump or crook regulator, causing excess fluid flow in some instances. Secondly, engine bay heat degradation of the tubes (car lives outdoors, auto trans, gets driven daily in hot conditions). Thirdly - contaminant possibilities.

I did follow one local expert's advice in the absence of Hydraurinçage, and added a litre of diesel for about one thousand miles, dropping the lot after that and bleeding/flushing/cleaning the system. It also occurred to me that possibly a garage engaged by the previous owner, could have topped up the fluid with DOT4.

Not knowing what sort of material the return lines really are, it's hard to do more than guess. It would seem likely they're a thermoplastic material, and that would often predicate eventual fatigue from drying/hardening.

Do they break in the UK, or are peoples' Xantia return lines still "soft as"?

Thanks, Adam.

Post by **xantia_v6** » 19 Dec 2009, 08:13

Can you just clarify whether you are referring to the thin plastic lines, or the rubber hose sections at joints?

I have not had a problem with either, but would suspect heat to be the issue.

If you are prepared to make yourself a bit of work, you could compare the brittleness of a piece near the engine with a piece somewhere cooler.

addo · Post by **addo** » 19 Dec 2009, 09:21

The thickish rubber return hoses - not the leak-back fine plastic lines. Realistically, in Sydney traffic at this time of year, the whole underbonnet just cooks. Even the aircon couldn't keep up properly on Thursday (but it is low on gas pressure).

Post by **Peter.N.** » 19 Dec 2009, 09:54

I tell you what, you send us some of that heat and we will send you some LHM

HDI · Post by **HDI** » 19 Dec 2009, 10:08

I have experience of the flexible hose & tubing industry as we had a family business as a distributor for 20 years and were involved with several manufacturers.
The problem will be due to heat degradation. You live in a country with one of the most extreme climates and this will accelerate the rate of degradation of rubber compound and just about every other man made material.
Although car manufacturers do environmental testing in extreme climates the less prestige brands will not specify materials so highly , generally just enough to get through warranty. This applies even more so if they don't shift as much product in a particular region.
The underbonnet environment is very severe and although there are rubber compounds that will last almost indefinitely in that area they are prohibitively expensive to use on a mid market brand. Heat is one thing , oil is another , both together are a witches sister to withstand over extended periods of time.
Certain applications use the high quality compounds due to safety , eg: fuel lines , power steering and belts.
Interestingly , Japanese manufacturers generally use higher quality compounds than other countries.

addo · Post by **addo** » 19 Dec 2009, 10:43

That seems to make sense. Some bits of the flex tubing, you could almost shatter with a hammer blow.

When things get hot, sometimes there is almost a chlorine smell to fumes that make it into the cabin ventilation. It's not the coolant or aircon, so I always assumed it came from the hydraulics.

HDI · Post by **HDI** » 19 Dec 2009, 10:56

That seems to confirm it , high temperature degradation over an extended period of time. Very similar to how I've seen hydraulic hoses fail on industrial equipment when the maintenance crews haven't kept the cooling systems working efficiently. Working temps increase and hose fails. One thing we often had trouble convincing our customers about was the temp rating of hose. They saw 100 Deg C in the spec and thought they could run it at that continuously. Well , yes they could , but the hose would have a significantly reduced life. The rating is a MAXIMUM , for continuous duty at high temps the hose must be derated or not used continuously at that temp. If a hose is needed to work at 100 deg C continuously a spec of say 150 deg C is needed.

Clogzz · Post by **Clogzz** » 19 Dec 2009, 13:38

a run of significant failures with the return lines

You’re not the only one, and it’s only the beginning.

The Citroën dealer in Southport told me that they all finish up (and finish) like that.
It’s caused by all that heat that we’re plagued with.

You can do repairs with fuel hose off the reel from the car tackle merchants, and spend time at Bunnings’ garden irrigation section to find white plastic T-pieces, adapters and joiners.
They’re quite solid, because they’re also meant to be out in the heat.
Then, you can spend hours in the heat under the bonnet to improvise your plumbing.

It’s out of the question to pay for the original Citroën hoses; the opening special is about $A250,

and 10 days’ wait to arrive from France.

If the return pipes into the LHM tank feel rubbery (not likely), they’re still good for a while.
If they’re like plastic, you will need a time machine to replace one after the other.
I have other things to kill the time, so the Xantia had to go.

Post by **leithant** » 24 Dec 2009, 02:24

I had one go when I was trying to stop it sucking air at the join.

I too have been wondering whether I've got a time bomb of hose failures too.

Clogzz · Post by **Clogzz** » 24 Dec 2009, 13:42

Yes, that’s their favourite breaking place.
The safest way is to gently pinch them a good distance from the joints to get the ‘feel’ of them.
If they’re not outright ‘rubbery’, they’re at risk of splitting.

Be especially wary of the two hoses returning from the brake doser valve.
They’re hidden high up under the windscreen ledge, where it’s hot from the exhaust below.
The doser also has a ‘good’ return flow, so you won’t fail to notice.