Xantia Air in LHM tank

mark g · Post by **mark g** » 22 Sep 2005, 16:13

Hi
I have just had my brakes bled due to Brake Pulsing Effect (Have done the brake mod.) When bleeding the LHM was all foam. Opened the LHM tank top to see inside and the LHM is all foaming. If I set the car in Highest setting then bubbles come through at the back left of the LHM tank, (if you are looking at the car from the front). As the bubbles come through the back left is it possible to say which pipe (if it is one that is corroded and letting air in) is responsible?
Thanks
Mark

Post by **martyhopkirk** » 22 Sep 2005, 16:46

Thats not likely to be air - its probably nitrogen fron a sphere.
How does the car ride / sit?

mark g · Post by **mark g** » 22 Sep 2005, 16:55

Hi
Car rides and sits fine, all spheres have good "bounce", two fairly new front ones and a fairly new Accumulator.
Should I clean the LHM filters, will they disperse the bubbles?
Mark

mark g · Post by **mark g** » 22 Sep 2005, 16:58

Sorry forgot to add whole point of theis is that the brakes have the "surging" effect. Hit the pedal they're on then off , then on etc. Have had new pads, discs, brakes bled etc. Done the brake mod, still the same. Thought it would be Doseur valve but when I changed spheres brakes were excellent for a few days. Then when changed accumulator, brakes excellent again for few days. I think air may be getting into the system and making the brakes act like this.
Mark

guillermo · Post by **guillermo** » 22 Sep 2005, 17:28

Dear friends,
I have heard that some times the imput hose ( the house form the LHM tank to the pump) may have very small holes or broken parts. since usually there is vacuum there, you don´t see big leakages, but once the pump works, some air get into the the hose, and then into the pump and teh system.
I hope this can help
Regards form southamerica
Guillermo

mark g · Post by **mark g** » 22 Sep 2005, 17:57

Hi
Thanks for the replies.
I have just taken the LHM lid off and removed both filters.
The round long one was filthy, now clean.
The smaller oval one has 2 small holes in it. Would these let the bubbles past rather than bursting them?
I have had to put it all back together again, and have noticed that the bubbles are still surging through, but also lhm is squeezing between the top of the oval filter and the plastic it attaches to on the lid. It is fully connected and also clipped on the bottom.
Any ideas?
Thanks
Mark

Mandrake · Post by **Mandrake** » 22 Sep 2005, 18:00

I agree with the suggestion of the hose from the tank to the pump leaking air - LHM is deliberately designed with "anti-frothing agents" and it is abnormal for it to froth like this, and it is highly likely that the pump is drawing in air and beating it together with the oil thus causing froth.
When I replaced the LHM and cleaned the tank/filters on my Xantia yesterday, when I initially started it up the oil in the tank suddenly went frothy on the top - this is a bit of air trapped in the feed pipe from the tank to the pump being sucked in by the pump, beaten up and pumped back to the tank again via the overflow.
(As you start off with the bleed screw open when bleeding air from the pump to regulator circuit)
After about a minute of idling with the bleed screw open the frothing went away, which indicates that all the air in the loop between the tank, to the pump, to the regulator, and back to the tank again was cleared of air.
If yours continues to froth indefinately with the bleed screw open then its almost certain that your pump is drawing in air...
Regards,
Simon

Mandrake · Post by **Mandrake** » 22 Sep 2005, 18:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mark g

Hi
Thanks for the replies.
I have just taken the LHM lid off and removed both filters.
The round long one was filthy, now clean.
The smaller oval one has 2 small holes in it. Would these let the bubbles past rather than bursting them?
<hr height="1" noshade id="quote"></blockquote id="quote">
There shouldn't be any bubbles to go past in the first place. The job of the filter is to trap sediment and grit, not to burst bubbles...
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
I have had to put it all back together again, and have noticed that the bubbles are still surging through, but also lhm is squeezing between the top of the oval filter and the plastic it attaches to on the lid. It is fully connected and also clipped on the bottom.
Any ideas?
<hr height="1" noshade id="quote"></blockquote id="quote">
Crikey, if you can see bubbles surging through, I think you've answered your own question ?? [:D]
Let the engine run with the regulator bleed screw open, and if you continue to see bubbles coming through indefinately you need to find the air leak to the pump and fix it...
Until that time bleeding the brakes is a waste of time as they will get air into them again in a relatively short time...
Regards,
Simon

Mandrake · Post by **Mandrake** » 22 Sep 2005, 18:29

Heres a suggestion of something easy to try that might fix the problem - the original hose clamps are a crimp type and when they and the hose get old they don't fit very tightly, and can sometimes leak.
Buy a couple of small stainless steel worm-screw hose clamps, and replace the clip at each end of the pipe from the tank to the pump. You shouldn't be able to turn the hose when the clamp is tight enough.
While you're at it, check the ends of the pipe to make sure they're not cracked and the rubber hasn't gone hard and/or stretched.
If too much oil spills out of the hose while you're working on it the pump wont be primed, so just pour some in with a funnel before reconnecting it.
Then make sure the bleed screw on the regulator is open and idle the engine. This will continously cycle the oil from the tank to pump to regulator to tank. Any air in the pipes will bubble out through the top of the tank and escape.
After a minute or two the frothing/bubbles should stop. If the frothing completely goes away, you've found your problem, and you should then do plenty of Citrobics to flush any remaining air out of the rest of the system, and bleed the brakes.
Regards,
Simon

mark g · Post by **mark g** » 22 Sep 2005, 19:17

Thanks everyone
1 more question the "bleed screw on the regulator", is this the nut with ball behind it that you use to depressurise the system or if not, where is it and where is the "regulator"? and how much do I undo it?
Thanks
Mark

Clogzz · Post by **Clogzz** » 22 Sep 2005, 19:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mark g
is this the nut with ball behind it that you use to depressurise the system and how much do I undo it?
<hr height="1" noshade id="quote"></blockquote id="quote">Yes, that's it, with a 12 mm head.
Undo by half a turn only, that's more than enough, and retighten only lightly.

mark g · Post by **mark g** » 22 Sep 2005, 20:24

Thanks very much. I have now bled the system with the bleed valve open and engine running. Lots of small bubbles appeared but continued flowing after 5 minutes with the valve open. I obviously have a leak. The brakes felt a tiny bit better and the suspension was definately softer so I'm pretty sure that air IS the culprit of all my problems.
Any ideas on how to find the leak?
Please don't tell me it could be coming from anywhere?
Thanks
Mark

jeremy · Post by **jeremy** » 22 Sep 2005, 20:45

Really there is only one place that air can get into the high pressure system and thats before the pump - ie the reservoir pickup and the rubber hose to the pump. The rest is high pressure (and I mean really high) and air cannot get in.
Some bubbles may get into the reservoir from the return system but this is harmless.
You can replace the hose from the reservoir to the pump with a section of clean garden hose for diagnostic purposes only.
Jeremy

mark g · Post by **mark g** » 22 Sep 2005, 20:50

Thanks for the reply.
Which pipe is this? Is it the on the reservoir the one that is closest to the front of the car ? And is the other end the thick pipe attached to the pump, again nearest the front of the car, that sticks up from the pump?
If it is and I test it with a hose, will I have to reprime the pump or anything, and will I lose alot of LHM from the hose I detach?
Sorry for all the questions!
Mark

jeremy · Post by **jeremy** » 22 Sep 2005, 21:45

Thick hose running from reservoir to pump. Use decent hose clips on it. you will loose a hose full of air and LHM as well probably as some from pump. Loosen pressure relief (bleed) screw on regulator, Fit pump end first, the fill hose with LHM, start engine, keep filling hose and stuff on reservoir and tighten up, allow to idle for a few minutes to clear air then tighten pressure relief screw and car should rise.
Jeremy