LHM leak :-(

Post by **RichardW** » 07 Aug 2006, 10:32

Was off last week. Got to my mate's house in Aberdeen and noticed some oily spots on the back of the Xantia

I have some sort of leak over the top of the rear subframe, on the N/S just above the brake pipe coil. It only leaks on a run (nothing new when standing idling, and no big leaks when going from high back to norm). Jacked it up and had the wheel off, but can't see anything (typical!) - except the leak is on the top of the subframe where there's no access. So, my guess is either a) the cylinder overflow pipe is holed or become disconnected; or b) the cylinder is stuffed and is dumping fluid out of the vent pipe. Anybody replaced the overflow pipe - where does it connect to the other side? If the cylinder is gone replacement doesn't look too bad - apart from the rusty pins and spheres - and this is a hydractive car, so has the fat pipes that will probably break off when I try to remove them

TBH I'm leaning towards the cylinder being stuffed, as this car sinks at the back to the stops shortly after switch off most times

slim123 · Post by **slim123** » 07 Aug 2006, 19:26

If the car sinks at the back, then the chances are that the cylinder is stuffed, or the brake valve is.

Asuming that the leak is tied in with the sinking, then the smart money has to go on the cylinder.

Check the pipes coming from the gaiter, the pipe closest to the sphere is the return pipe, this pipe will have some fluid in but not a lot as it only carries the leak off from the cylinder back to the reservoir, if it's at full flow, then you have got cylinder troubles.

Then check the second pipe, the black one. This pipe is only an air pipe, it's function is to stop the gaiter from blowing up like a balloon as the cylinder goes back and forth, this pipe should be dry, if this pipe has fluid in it the fluid will end up inside the subframe and drip out.

Hope this helps in some way.

Regards
Slim

Post by **RichardW** » 07 Aug 2006, 20:50

Just spent a bit of time under it - access is improved with the spare wheel and carrier removed

Still can't figure out exactly where it's coming from, but it looks like either the cylinder return or hydractive valve return pipe where they go over the top of the subframe. Access? Er, no..... Going to book it into the stealer nearest work, and get them to change both return pipes and see what happens then.

slim123 · Post by **slim123** » 07 Aug 2006, 21:21

Richard.

There is a horrible little rubber "T" piece on top of the rear sub-frame on the nearside, it is a right pig to get to and I will take an easy guess and say that it's split.

Even to do this standing up under a ramp, it is a case of long nose pliers in each hand and a maglight sticking out of yer gob!!

Good luck.

Slim

Post by **RichardW** » 10 Aug 2006, 07:46

Into the dealer yesterday. Relieved of £60 to reconnect the leak off hose. So why did it come off then? Excess pressure I think due to leaking susp unit. Was about to start a book on how long it would stay reattached, but by the time I got back to work this morning (60 mile round trip), it has already let go

- no time for getting a book up! So looks like I am in for a new susp unit - will have to try and diagnose which one tonight, then get busy with the WD-40 on the clips and pipes. Ho hum

citronut · Post by **citronut** » 10 Aug 2006, 09:11

if it is a susp unit letting to much presure past the seals,the easyest way to find out which one would be pull the pipes out of each susp unit gaitor,you will see which one has the most fluid coming out of it,or if it that bad youmight be able tofeel the gaitor to determin how much fluid is in side
regards malcolm

Post by **RichardW** » 10 Aug 2006, 21:05

Turns out to be the hydractive return pipe - had completely come off this time, and it comes out with quite a squirt when the valve cycles - hence the LHM being everywhere. Now refitted, and added 2 cable ties 8) . See how long it stays on

Not sure if there is really a worse fault then there's been for the last 40k miles, or if it's just worked loose over time. We'll see!

citronut · Post by **citronut** » 10 Aug 2006, 22:22

if the pipe that keeps coming off is one of the two from the susp unit gaitor,one is a vent the other is a seepage return for any fluid which gets past the presure seal,which sould be very slight if any,defenatly should not be a flow of fluid
regards malcolm

Post by **RichardW** » 21 Aug 2006, 08:07

Well, it lasted about 700 miles this time

Now refitetd with 3 cable ties - including one behind the bulge in the plastic pipe - all wired together. Will probably just blow the pipe off somewhere else now

Anybody know the configuration of the return lines - does this go straight back to the tank, or does it connect up with some others? I guess first port of call is to fit a new electrovalve on the rear hydractive valve - unless anyone thinks the line is connected to something else that might be causing excess return pressure - like the front electrovalve - this hisses after the engine is shut down.

citronut · Post by **citronut** » 21 Aug 2006, 08:43

i would first disconect both trickle return pipes from both susp unit gaitors,then start the engine put suspention up on high,then switch off engine and let suspention down,inbetween each of these procedures check if you have any fluid coming out anywhere,this should tell you which direction the presure is coming from,if it comes out of one or both of the suspention gaitors it is that unit which is letting to much presure by th seals,and if its coming out of one of the plastic pipes it means you have somthing elss alowing high presure into the seepage return system
regards malcolm

Post by **RichardW** » 21 Aug 2006, 09:54

Cheers Malcom, but this is a hydractive car, and it's the return pipe from the hydractive electrovalve that is coming off - this is a separate return from the suspension units. It appears that when the pipe is off, the LHM is coming from the hydractive unit end, rather than the pipe going to the front of the car - although what is not clear to me is whether there is too much return from the hydractive unit at the back, or there is a problem down at the front of the car that is causing too much back pressure, and this joint at the rear is the weakest link. If it comes to it, I might run a new return straight back to the top of the tank

Mandrake · Post by **Mandrake** » 21 Aug 2006, 10:45

Hi Richard,

If you're talking about the rubber return hose connected to the end of the Hydractive Electrovalve, there should never be any significant continuous flow coming from the valve.

Inside is a double ended tapered needle valve. In the energized mode the HP input port is open and the overflow port is closed. In the off mode the HP input port is closed and the overflow is open. The common junction goes to the slide valve in the main Hydractive body.

In both modes there should only ever be at most a tiny dribble coming from the valve, but when it switches modes it will "spit" a small quantity of high pressure oil out as the needle valve moves.

What can happen is they can get leaky - this happened to my front electrovalve, in the on mode it was continously leaking via the overflow port enough that you could hear a "hissing" coming from the valve.

Disassembling it after replacing it showed the problem to be caused by a tiny bruise on the taper on the end of the pin preventing it from sealing properly. How it got like that I have no idea....

Having said all that even that amount of leakage shouldn't be able to push the hose off....(it certainly didn't push the hose off mine) sounds like the hose has gone hard or it isn't clamped tightly enough.

Plastic cable ties won't be enough, they're originally fitted with a standard crimped steel band and I replaced mine with a jubilee clip when I refitted the pipe...

This line is actually a medium pressure overflow return, not a low pressure leakback pipe like the ones coming from the rear suspension cylinder gators, and therefore needs to be securely clamped unlike some of the leakback lines which are just plastic pipes with a push fit into rubber joints.

Another possibility is another overflow line which joins that line further upstream has excessive leakage or there is a blockage further upstream and its causing the weakest joint to pop off...(but once again it should still be secure enough that even that shouldn't pop it off...)

Regards,
Simon

Post by **RichardW** » 21 Aug 2006, 12:26

Simon

"If you're talking about the rubber return hose connected to the end of the Hydractive Electrovalve, there should never be any significant continuous flow coming from the valve. "

That's the one. Not really a continuous flow, just as you say a spit when the valve actuates.

"Plastic cable ties won't be enough, they're originally fitted with a standard crimped steel band and I replaced mine with a jubilee clip when I refitted the pipe... "

There's a steel band where the hose is attached to the valve. The joint that's coming adrift is where pipe 8 (the rubber hose) attaches to pipe 5 (hard black plastic pipe) in this diagram:

Rear return piping

It doesn't look like it's ever had a clip on it.... but reading that diagram again it does common up with the suspension return. Looking at the front return piping, this commons up with the front strut returns as well (top LH corner):

Front return piping

So it could still be a problem with the suspension cylinder(s).....

Looks like I will need to try and see if there is excessive flow from the cylinders anyway. Do not want to be replacing £100 electrovalves on a whim!

citronut · Post by **citronut** » 21 Aug 2006, 13:28

sorry Richard
i had forgot what was said earlier,but even still if there is no fluid coming out of this pipe when disconected i will not be any other device or unit causeing you problem
regards malcolm