lhm leak

davethewheel · Post by **davethewheel** » 30 Jun 2005, 03:17

driving my xantia td home tonight the stop light flashed on a couple of times and on further inspection i found the oil level to be very low, i can't seem to find any leaks apart from were there is 2 pipes going into the accumulator ,it's been leaking from around there for about a year now ,both nut's are tight is there some kind of seal or o ring in there that might need replacing. [:)]

Post by **Richard Green** » 30 Jun 2005, 04:00

just nip the bolts up a little because its a common problem on the bypass valve

jeremy · Post by **jeremy** » 30 Jun 2005, 04:19

I presume you do mean LHM level not engine oil? The reason I mention it is that on many Citroen systems the engine oil light is used as a timer for the other warning liughts - so low engine oil will put on the stop light (and others as well)
Over a long period a very small leak will add up to a reasonable loss and so the 2 pipes you suspect may be to blame. They will have the usual Citroen hydraulic seal on them - looking like a short length of cutoff rubber tube. By and large these joints are reliable but they can leak if the pipes are not central or are strained. The fixings are not supposed to be done up very tight (unlike for example a conventional brake pipe) and as the pipes in question are probably in an awkward place, may not have been tightened sufficiently in the first place.
If this is not the case - ie they seem straight and tight then new seals may be required. The are obtainable for less than 50 p each if they are the ones I think they are. (the bigger one is less than £1.)
Are the suspension and accumulator and other spheres in good condition? The reason I ask is that if a sphere diaphragm ruptures it will take in about 1/2 litre of LHM. There is loads on here about sphere testing and replacement of the sphere and topping up will cure the problem.
I'm curious about the bypass valve that Richard mentions - and wonder if he could explain to me where it is and what its purpose is.
Jeremy

Post by **Richard Green** » 30 Jun 2005, 04:38

no problem Jeremy mate, the bypass valve is on the accumulator just below the vent bolt, real name is a safety relief valve the rest is obvious.

Post by **Richard Green** » 30 Jun 2005, 04:43

also a very common problem in the system due to lack of service of fluids.

Post by **Richard Green** » 30 Jun 2005, 04:52

to put it another way the valve sticks open and the suspension/breaks acts erratic due to loss of pressure and that's why its their it bleeds back to the header tank.

jeremy · Post by **jeremy** » 30 Jun 2005, 04:58

The sphere is attached to the regulator. The regulator is fitted with a bypass (otherwise known as a bleed) valve which is in the form of a ball bearing held onto its seat by a bolt. It is not a troublesome component and I have never found it prone to leakage down the bolt shaft and to the outside and I have not seen any postings suggesting that anyone else has found it to be a problem either. Should it work loose (again never heard of) the hydraulic system would fail altogether as there would be no system pressure.
The safety valve which inter alia operates the warning light is an entirely separate component and would be the next component in the circuit.
jeremy

AndersDK · Post by **AndersDK** » 30 Jun 2005, 05:00

Richard - this valve is most widely known as the Pressure Relief Valve. But you are right that this valve in open condition simply bypasses the regulator - i.e. lets the pump idle the LHM through the reservoir filters.
Dave - there is another wellknown reason for the LHM to "disappear" without dripling down the road. This is when the spheres have lost some of their gas precharge. This then causes more LHM to be pressed into the sphere on the "wet" side of the membrane to compensate - thus suddenly one morning you are taking off you get the red STOP light.

davethewheel · Post by **davethewheel** » 30 Jun 2005, 05:02

i've tried to nip up the bolts and they are tight the pipes look straight also, as to the condition of the sphere's the 4 for the wheels were changed about a year ago and i think the accumuator one is ok, also flushed and changed the lhm at around the same time, i must admit i don't think i've checked the level since so maybe it's lost the fluid through the leaking pipe it does tend to leave a drop over night were the car is parked, i've changed pipes on a citroen before so i am familiar with the type of seal that is normaly used but iv'e never had one leak before, there is two sizes of pipe coming out of the accumulator and one is quite large, is it the same type of seal as on the smaller pipes.

bxbodger · Post by **bxbodger** » 30 Jun 2005, 05:05

If the nuts are "tight", they may be too tight- if they have been done up a bit too enthusiastically in the past it may have mashed the seals up, if so, do as Jeremy suggests and replace them. They just push on.
They tend to get overtightened in garages, but they shouldn't be- what makes the seal is the hydraulic pressure causing them to swell slightly, as opposed to tight compression in "normal" hydraulic brake systems.
Just take a peek under your front wheelarches as well, and check if theres any LHM splattered around there- a rubber return pipe from a front strut may have died on you. When I was new to Citroen hydraulics this happened to me, the warning light came on, the LHM was low, I spent ages looking for leaks under the bonnet, and it was only by chance that I was parked with the wheels turned that I saw the lhm under the arch............[:I]

Post by **Richard Green** » 30 Jun 2005, 05:15

what ever you call it its a pressure relief valve and is separate from the sphere, the pipes just pop in so a pressure expansion means the the pipe pops off hence the leak, something I have one across many times but worth a mention.

jeremy · Post by **jeremy** » 30 Jun 2005, 05:16

Dave there are 3 sizes of seal used in Citroen hydraulics. There is a PDF of the Citroen BX parts list on the citroenZ site which will have the BX applications. From what I remember the one on the pump is the large size but I can't remember what size is used on the regulator.
I'd imagine the Xantia regulator is similar to a BX one.
http://www.citroenz.com/
jeremy

Post by **Richard Green** » 30 Jun 2005, 05:19

sick of edit so I meant come not one durn spell checker.

Post by **Richard Green** » 30 Jun 2005, 05:22

they are the same Jeremy mate, little has changed on a superb system.

davethewheel · Post by **davethewheel** » 01 Jul 2005, 00:28

cheers guys all sorted now, replaced the seal on one of the pipes and seems to have sorted it now, will get an eye on the fluid levels just in case i've got a leak from somewere else but it looks ok. [:D]