Xantia, no brakes, new accumulator fitted.

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JohnT
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Xantia, no brakes, new accumulator fitted.

Post by JohnT »

1.9TD. 1995. Standard. Driving me nutty! Just fitted (second)new accumulator sphere but no improvement. Brake force is gone within 1/2 hour of standing. When started it drops within about five seconds, but regains quite quickly. The rest of the spheres have been changed within last few months. Pump ticks 20 seconds. Done citrobics. Any ideas please? Thanks!
JohnT
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Post by JohnT »

Since checking previous threads I have noticed Mandrakes and Petes comments on cleaning tha ball seal on the regulator.....should I try this? Car does not regain height if I sit on the boot when engine is switched off.
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AndersDK
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Post by AndersDK »

Dear John !
It is absolutely & completely normal behaviour for a Xantia (& BX, & CX) to ooze out the pressure from the accu sphere after ½ an hour. It's one of the fundamental differences with these cars that you <font color="red"><i>CAN NOT & NEVER SHOULD</i></font id="red"> expect the brakes to function shortly after engine (and then hydraulic pump) is stopped.
Many an owner has bumped into family's second car or other obstacles (i.e. your house) in the driveway because of this.
After 10 years of service you can not expect your Xantia to be perfect. Before you do anything drastic and fork out for large investment in workhours or spares, then you should test the flowback from the SMALL rubber hoses at the reservoir. With engine idle, height settled at normal and no other pressure absorbing activity, you shoiuld of course not have a flow loss at the reservoir.
If any found - then trace back to the component which causes the flow.
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Post by JohnT »

Thanks Anders....you learn something every day....will do what you said, thanks!
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Mandrake
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by JohnT</i>

1.9TD. 1995. Standard. Driving me nutty! Just fitted (second)new accumulator sphere but no improvement. Brake force is gone within 1/2 hour of standing.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
You mean half an hour of standing with the engine off ? As Anders points out, you shouldn't rely on there being any brake pressure a long time after the engine is turned off.
On a healthy hydraulic system you should expect to be able to apply the brakes about 20 times immediately after the motor is turned off before the reserve pressure is used up and the pedal starts to become soft. This gives you ample time to stop on the side of the road if the engine fails, or the hydraulic pump belt (the aux belt) breaks.
Any more than this is a bonus. Yes, some cars will still have quite a bit of accumulator pressure half an hour after turning off the engine but don't count on it, and I wouldn't expect it on a 10 year old car. (And definately don't maneuvere the car around your section with the engine off unless you want your garden wall redesigned [:D])
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
When started it drops within about five seconds, but regains quite quickly.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
At the back only, or at the front and the back ? If its a large drop only at the back it could be the anti-sink sphere.
Is it a hydractive 2 model ? If so, there is normally a small drop at both ends when starting up as the hydractive solenoids engage and equalize the pressure of the middle spheres.
Sometimes due to various other factors this can happen a bit late in the process - on my HA2 Xantia the back has started the annoying habit of lifting, followed by the front, then the back will suddenly drop a few inches then lift again. At the moment I'm still in persuit of this gremlin.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
The rest of the spheres have been changed within last few months. Pump ticks 20 seconds. Done citrobics. Any ideas please? Thanks!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
20 seconds is too often. My accumulator sphere was down to 15 seconds when I replaced it, and went up to a minute and a half after replacement.
Are you SURE the accumulator sphere is ok, and was a new one not a reconditioned one ? Out of all the spheres in the system, the accumulator one is under the most strain, as it is constantly under the full pressure of 170 bars during operation, and reconditioned or regassed accumulators have a nasty habit of failing quickly.
If you check back through some threads by Crispy you'll see that he got sold a "new" accumulator that turned out to be reconditioned when he questioned the garage a second time, and it failed during the drive home !! So don't think that it can't happen.
If it is ticking every 20 seconds there is only two possible reasons -
(a) accumulator sphere is in fact faulty, even though recently replaced, (possibly failed prematurely if it was a reconditioned one)
(b) excessive leakage of the high pressure source.
In the case of b, it might be leakage in the regulator itself (the bleed valve, or the non return valve) or it could be leakage in any of the other devices in the system that run from the high pressure supply. (Height correctors, brake control valve, anti-sink valves etc)
Anders suggestion of looking for excessive leakage in the return pipes to the tank is a good one, although I'm not sure how you would easily trace the pipes back to their source....(physically rather difficult to follow them...)
Regards,
Simon
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Post by kafkaian »

Can you let us know what happens John when you resolve this?
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Post by jeremy »

The accumulator should be able toraise the car when you sit in the boot having just turned the engine off. I agree with Mandrake that 20 seconds is a bit often for ticking but may not be much to worry about in the short term.
Try raising the car to full height and see what the ticking rate is then. The suspension spheres are now functioning as accumulators as well as the height correctors are open and so the ticking rate may drop and if it does then the accumulator sphere is probably defective. ifit were flat I think the ticking would be nearer 10 seconds.
Ticking is caused by LHM escaping from the accumulator. there are a number of ways it can go.
1. The way its meant to go - onward down the circuit to the safety valve and beyond. With the car static at normal height it should settle and anything going this way will be leakage.
2. Down the piston in the centre of the acc sphere mounting. This is unlikely unless grit has got in.
3. Back the way it came - via the non-return ball valve. This can be reseated by tapping it smartly using a brass punch. It lives under the steel plate bolted to the sphere mount. On TD BX this job can be done with the regulator in position on the car.
4. Problems with the pressure relief screw. This is the bolt on the front of the regulator and shlould be used to depresurise the system and assist with priming during service. Under the bolt is a ball bearing and the bolt should only be cracked open. Sometimes it is removed and the ball bearing falls out. - extensive leakage from accumulator!
All this assumes that there is no air getting into the system. The most common source of air is problems with the hose connecting the reservoir to the pump which either perises or is damaged or poorly clamped at the reservoir end. As its under suction it doesn't leak externally. Air can cause all sorts of wonderful and untraceable problems. for test purposes it can be substituted by a section of clean garden hose. Heater hose is probably soluble in LHM.
Have a search for the Chrispy thread - I seem to recall just about every permutation was gone into there!
Jeremy
JohnT
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Post by JohnT »

Thanks so far....this is the second brand new sphere, anti sink was changed three months ago. Will try out the rest of the tips this weekend and will get back to you, thanks again.
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