Hi,
My 93 Xantia VSX (1.9TD, 105000 miles) has a problem with the brakes.
When I press the brake pedal, there is a delay of about 1 second before the brakes actually come on. The brakes themselves actually work very well (once they come on).
It also feels like they take a moment to release when I take my foot off the pedal (I've tried this on a slight slope and there was a definite delay between releasing the brake pedal and the car starting to roll).
By the way, this behaviour is not just from start-up, it happens all the time (though if I re-apply the brakes within a couple of seconds of releasing them, they work correctly).
I would appreciate any ideas.
Thanks,
Stuart, York.
93 Xantia VSX Brake Problem
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RichardW
- Forum Treasurer
- Posts: 12440
- Joined: 07 Aug 2002, 17:12
- x 1430
Stuart,
I would try bleeding the brakes first, as air sounds the most likely cause. Is is really a delay, or just more travel than you are expecting? If you bleed and find no air, and the situation does not improve then you might have to look at replacing the brake valve, but you'll need some more tests to confirm if this really is worn out as a) it's quite expensive and b) it will be a bugger to change!
Note, if you're not familiar, bleeding Cit brakes is a bit different to 'ordinary' cars:
Do it with the engine running, wedge the brake pedal down with a piece of wood off the drivers seat, then open (carefully!) the bleed screw with a tube into a pot. When clean, air free, LHM flows shut the bleed screw and move onto the next wheel. For the rears, put the suspension in high, jack up one side only, and bleed that side, refit the wheel and then move to the other side. Bleeding the brakes should also tell you if you have a flow problem to one or more of the brake calipers.
Also has your rear antisink sphere been changed - this can cause all sorts of weird behaviour if it's flat.
Hmm, it's also VSX and therefore presumably has ABS? Problems with the computer and sensors are not unknown, but probs with the hydraulic block are rarer, but cannot be discounted.
I fear you may be into a time consuming fault tracing before you nail it down - sorry!
Richard
I would try bleeding the brakes first, as air sounds the most likely cause. Is is really a delay, or just more travel than you are expecting? If you bleed and find no air, and the situation does not improve then you might have to look at replacing the brake valve, but you'll need some more tests to confirm if this really is worn out as a) it's quite expensive and b) it will be a bugger to change!
Note, if you're not familiar, bleeding Cit brakes is a bit different to 'ordinary' cars:
Do it with the engine running, wedge the brake pedal down with a piece of wood off the drivers seat, then open (carefully!) the bleed screw with a tube into a pot. When clean, air free, LHM flows shut the bleed screw and move onto the next wheel. For the rears, put the suspension in high, jack up one side only, and bleed that side, refit the wheel and then move to the other side. Bleeding the brakes should also tell you if you have a flow problem to one or more of the brake calipers.
Also has your rear antisink sphere been changed - this can cause all sorts of weird behaviour if it's flat.
Hmm, it's also VSX and therefore presumably has ABS? Problems with the computer and sensors are not unknown, but probs with the hydraulic block are rarer, but cannot be discounted.
I fear you may be into a time consuming fault tracing before you nail it down - sorry!
Richard
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alexx
- Posts: 462
- Joined: 19 Nov 2002, 02:42
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stuartb
- Posts: 44
- Joined: 20 Feb 2003, 14:12
RichardW, It is definitely a delay - It doesn't matter how hard I push the pedal, the brakes do nothing for about a second (Usually followed by my nose flattening against the windscreen [:D]
I don't think my car has an antisink sphere (it's a '93 model).
Although it has ABS, this is not working nor has it ever worked in the 3 months or so that I've had the car (I recently replaced all the blown bulbs in the instrument pack and had to remove the ABS warning bulb for that very reason). Fixing the ABS is something I'll do when I find a round tuit[:)]
I'll try bleeding the system first (since it's free and relatively easy) and see if that fixes things.
Alexx,
I'm not aware of too much ticking from the regulator, but I'll certainly check it.
One thing I have noticed is that when I press the brake pedal, I can hear the hydraulic pump run just before the brakes actually come on.
Thanks to both of you for your help - I'm pretty good at wielding the spanners, but this is my first 'pump-up' Cit. I bought it because I was so pleased with the ZX 1.9D (which is now the wife's car). So far, I like the Xantia a lot and if I can just fix this problem, I'll be really chuffed with it!
As an aside, I gave a Jag XJ8 owner a lift the other day, and he commented on how smooth the ride was in the Cit!
Cheers again.
I don't think my car has an antisink sphere (it's a '93 model).
Although it has ABS, this is not working nor has it ever worked in the 3 months or so that I've had the car (I recently replaced all the blown bulbs in the instrument pack and had to remove the ABS warning bulb for that very reason). Fixing the ABS is something I'll do when I find a round tuit[:)]
I'll try bleeding the system first (since it's free and relatively easy) and see if that fixes things.
Alexx,
I'm not aware of too much ticking from the regulator, but I'll certainly check it.
One thing I have noticed is that when I press the brake pedal, I can hear the hydraulic pump run just before the brakes actually come on.
Thanks to both of you for your help - I'm pretty good at wielding the spanners, but this is my first 'pump-up' Cit. I bought it because I was so pleased with the ZX 1.9D (which is now the wife's car). So far, I like the Xantia a lot and if I can just fix this problem, I'll be really chuffed with it!
As an aside, I gave a Jag XJ8 owner a lift the other day, and he commented on how smooth the ride was in the Cit!
Cheers again.
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mbunting
- Posts: 712
- Joined: 21 Dec 2001, 15:19
If the pump runs as soon as you press the brakes, then I would say you either have a leak somewhere, or your accumulator sphere is duff.
Run the car at idle, with the handbrake on, don't touch anything else.
Listen very carefully for a cerrlick type of noise, and count the number of seconds in between each cerrlick ( like it
)
Any less than 10 seconds is dangerous, replace your accumulator sphere. Between 10 and 30 seconds is dodgy - replace it, above 30 seconds is OK.
This click is the pressure regulator building up the pressure in the accumulator sphere - used for your brakes. The shorter the delay is, the less pressure it can hold - no pressure no brakes !
Run the car at idle, with the handbrake on, don't touch anything else.
Listen very carefully for a cerrlick type of noise, and count the number of seconds in between each cerrlick ( like it
)Any less than 10 seconds is dangerous, replace your accumulator sphere. Between 10 and 30 seconds is dodgy - replace it, above 30 seconds is OK.
This click is the pressure regulator building up the pressure in the accumulator sphere - used for your brakes. The shorter the delay is, the less pressure it can hold - no pressure no brakes !
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alexx
- Posts: 462
- Joined: 19 Nov 2002, 02:42
Well, as long as the engine is running, there is always enough pressure for brakes (except a few second after you switch it on), even with totally flat accumulator sphere, so the safety is not in question.
Anyway, if something happens with the engine, with flat sphere you are immediately out of braking force for front brakes, while with good sphere there is a reserve for at least 50 applying of brakes, and braking force will diminish gradually, so you will notice.
On Xatias without anti-sink, even with flat acc. sphere and engine switched off, rear brakes will work until rear end totally settles down. On Xantias with anti-sink, rear brakes will work until the pressure in anti-sink sphere is exhausted (well, if it's also flat, it will be quick).
Anyway, if something happens with the engine, with flat sphere you are immediately out of braking force for front brakes, while with good sphere there is a reserve for at least 50 applying of brakes, and braking force will diminish gradually, so you will notice.
On Xatias without anti-sink, even with flat acc. sphere and engine switched off, rear brakes will work until rear end totally settles down. On Xantias with anti-sink, rear brakes will work until the pressure in anti-sink sphere is exhausted (well, if it's also flat, it will be quick).
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stuartb
- Posts: 44
- Joined: 20 Feb 2003, 14:12
Well, I've tried to bleed the system, but I just can't seem to get rid of all the air (or nitrogen?). So far, I've only bled the nearside front brake, and I've taken so much frothy LHM out, that I've had to add 2 litres to the reservoir (while bleeding the brake to keep the level up).
When I look in the LHM reservoir with the engine running, the fluid that's being returned is very aerated. Help! I don't mind fizzy drinks, but I don't want fizzy LHM!
When I look in the LHM reservoir with the engine running, the fluid that's being returned is very aerated. Help! I don't mind fizzy drinks, but I don't want fizzy LHM!
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alexx
- Posts: 462
- Joined: 19 Nov 2002, 02:42
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allmond
- Posts: 214
- Joined: 28 Feb 2001, 01:02
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stuartb
- Posts: 44
- Joined: 20 Feb 2003, 14:12
Alexx: I think that confirms what I suspected. I've actually bought a new accumulator sphere from AS today, unfortunately, they didn't have the sphere removal tool in stock at Leeds. All attempts so far to remove the old one have failed (including breaking a brand new chain wrench (the 1/2in square drive type!)
Any suggestions on how to remove the offending sphere without the tool would be gratefully received!
Allmond: There must be THAT much and more! I've attempted to bleed the system via the 12mm bolt on the pressure regulator numerous times today (after I gave up trying to remove the sphere). There is still a LOT of air in the fluid.
Any suggestions on how to remove the offending sphere without the tool would be gratefully received!
Allmond: There must be THAT much and more! I've attempted to bleed the system via the 12mm bolt on the pressure regulator numerous times today (after I gave up trying to remove the sphere). There is still a LOT of air in the fluid.
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AndersDK
- Posts: 6060
- Joined: 21 Feb 2003, 04:56
- x 1
It's perfectly normal to see air in the reservoir from the return lines. This is because the controlling valves has a jet-action, when releasing pressurerized LHM out in the air cavity inside the return hoses/pipes.
If air in the system seems to be an "impossible" problem to get rid of, allways CHECK the reservoir FILTERS for any cracks or holes. The fine filter mesh also traps or breaks down air bubbles.
Even the smallest amount of air in a hydraulic system is unwanted, because the air is so easily compressed/expanded, contrary to the fluid.
Also check the pump feed deep intake diptube in the fiter "manifold".
And Stuart :
You wo'nt see ANY bettering of problems, if you just bleed one side's brakes. ALL the brakes must be bled, since the calipers on same axle are directly inteconnected by piping/hosing.
Another point worth remembering :
ABS has nothing to do with these kinds of brake problems.
Even with a 100% dead ABS system, the brakes are simply working as in older cars with no ABS system fitted. The ABS brake pressure control valves are designed such, that they are allways left fully open, to allow pressure reaching the brakes, should the ABS system fail.
To my experience, you may simply have a very common problem :
the brakes has been exposed to very sluggish garage service, only covering replacement of discs & pads.
A simple service covering a complete caliper dismantling & a repair set, may be your only effective solution. This is btw. one of the exercises, ALL car DIY'ers should master perfectly, considering the simple, but time consuming work.
BTW : the pressure release screw on the regulator is NOT an air bleed screw.
Air in system is automatically bled via return hoses, if the suspension is exposed to some regular exercise. But the brakes MUST be bled manually.
If air in the system seems to be an "impossible" problem to get rid of, allways CHECK the reservoir FILTERS for any cracks or holes. The fine filter mesh also traps or breaks down air bubbles.
Even the smallest amount of air in a hydraulic system is unwanted, because the air is so easily compressed/expanded, contrary to the fluid.
Also check the pump feed deep intake diptube in the fiter "manifold".
And Stuart :
You wo'nt see ANY bettering of problems, if you just bleed one side's brakes. ALL the brakes must be bled, since the calipers on same axle are directly inteconnected by piping/hosing.
Another point worth remembering :
ABS has nothing to do with these kinds of brake problems.
Even with a 100% dead ABS system, the brakes are simply working as in older cars with no ABS system fitted. The ABS brake pressure control valves are designed such, that they are allways left fully open, to allow pressure reaching the brakes, should the ABS system fail.
To my experience, you may simply have a very common problem :
the brakes has been exposed to very sluggish garage service, only covering replacement of discs & pads.
A simple service covering a complete caliper dismantling & a repair set, may be your only effective solution. This is btw. one of the exercises, ALL car DIY'ers should master perfectly, considering the simple, but time consuming work.
BTW : the pressure release screw on the regulator is NOT an air bleed screw.
Air in system is automatically bled via return hoses, if the suspension is exposed to some regular exercise. But the brakes MUST be bled manually.
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Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- x 2
As Anders suggests, the foaming of LHM in the reservoir is not necassarily indicative af any problem with air or gas in the system, though nor is the possibility discounted.
Depending on how long this problem has been going on it could be air being sucked in some where along the pump intake tract, because most of the gas from a leaking accumulator (my calculations put it at around 25 litres, any takers) should have gone through the suspension system, and been vented back to the reservoir, not gone into the front brakes (which are dead ends) in this sort of quantity, but we remain to see what a new sphere does, keep us posted Stuart.
Dave
Depending on how long this problem has been going on it could be air being sucked in some where along the pump intake tract, because most of the gas from a leaking accumulator (my calculations put it at around 25 litres, any takers) should have gone through the suspension system, and been vented back to the reservoir, not gone into the front brakes (which are dead ends) in this sort of quantity, but we remain to see what a new sphere does, keep us posted Stuart.
Dave
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alexx
- Posts: 462
- Joined: 19 Nov 2002, 02:42
Hm, Anders, I'm not sure I understand the sentence "...the controlling valves has a jet-action, when releasing pressurised LHM out in the air cavity inside the return hoses...". Return pipes are filled with LHM and there is no air, I think (where from?). Anyway, I looked in LHM tank several times, and there were no bubbles at all, although BX is 14 years old.
Of course, air can be sucked into the system if there is a hole in HP pump plastic suction hose inside LHM tank, but I don't think it's very likely. It could be also a rubber supply pipe, but in than case, it would be probably leaking when the engine is off.
Stuart, did you try hitting the sphere on the waist with chisel and hammer? It usually works.
Of course, air can be sucked into the system if there is a hole in HP pump plastic suction hose inside LHM tank, but I don't think it's very likely. It could be also a rubber supply pipe, but in than case, it would be probably leaking when the engine is off.
Stuart, did you try hitting the sphere on the waist with chisel and hammer? It usually works.
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stuartb
- Posts: 44
- Joined: 20 Feb 2003, 14:12
Anders: Thanks for the reply. Thanks for the suggestion about the reservoir filters - I'll have to take a look. I know that I will have to bleed all the brakes - My comment about not being able to get the air out of the nearside front brake is just an indication. After trying that one, I thought I should take a look at the overall system, not just the brakes. Also, I was pointing out that the ABS doesn't work for 'background information' - I didn't think it would be likely to be a cause of my problems.
Dave: Thanks also to you for your reply. The LHM being returned to the reservoir is so foamy that I suspect there is still air in by the time it gets back to the inlet side of the pump ready to start it's next journey round the system. Obviously, I could be wrong about this - it's just a feeling!
Cheers,
Stuart.
Dave: Thanks also to you for your reply. The LHM being returned to the reservoir is so foamy that I suspect there is still air in by the time it gets back to the inlet side of the pump ready to start it's next journey round the system. Obviously, I could be wrong about this - it's just a feeling!
Cheers,
Stuart.
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stuartb
- Posts: 44
- Joined: 20 Feb 2003, 14:12
Alexx: Sorry, I guess we were both replying at the same time!
I haven't yet tried the old hammer and chisel routine. I don't know why I haven't tried it yet - It's a routine I'm very familiar with!
I'll give it a go tomorrow morning. I'm just so frustrated to actually have the new accumulator sphere waiting to go on and (hopefully) fix my problems.
Cheers,
Stuart.
I haven't yet tried the old hammer and chisel routine. I don't know why I haven't tried it yet - It's a routine I'm very familiar with!
I'll give it a go tomorrow morning. I'm just so frustrated to actually have the new accumulator sphere waiting to go on and (hopefully) fix my problems.
Cheers,
Stuart.