Intermittent braking issues 98 Xantia 2.1TD

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scooobydont
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Intermittent braking issues 98 Xantia 2.1TD

Post by scooobydont »

Hi All,

First time Citroen owner here. I have a 98 2.1TD Xantia which has been pretty much flawless for 3 years (still on its original back tyres!). The car has done 70k.

The ABS light has started to come on randomly whilst driving. When the light is not on occasionally the brake pedal is going rock solid and I have had to stamp on the pedal to get the car to stop (servo does not seem to work). After this the pedal seems to return to normal. Also in the mornings there is a light metallic scraping (?) noise coming from the from of the car. This clears after the brake pedal has been pressed a few times.

I have had the car in to a local garage and they have advised a leak in the hydraulic system and would have to take to a main dealer to fix. I do not trust their diagnosis (I dont think they looked at all TBH!) as the fluid level in the hydraulic top up tank is not dropping and there are no green 'spots' left on the road under the car.

Can anyone advise what I can check or if someone has had similar symptoms?

I am trying to rule out all possibilities before booking it in to Citroen to investigate as I guess it will cost a fortune!!

Thanks in advance.
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Post by myglaren »

What is the tick rate like?

Some of your symptoms seem to indicate a flat accumulator sphere.
The scraping seems to me to point to a sticking brake piston.
Intermittent ABS warning could be many things, I'd have a rake through the forums for similar problems but could be a failing sensor, poor connections or muck on the dragon's teeth.

Note that you do not have a brake servo! It is all driven by the hydraulic pressure.

What does the LHM look like?

If the tick rate is <20" then I would initially bleed the hydraulic circuit, then the brakes and see what results that gives.
If the LHM hasn't been changed for a while and looks dirty or yellow/brown, flush the system with Total Hydroflush (Hydrorincage) then renew the LHM.

Take a look at Jim's Guide and not the warnings!

Where are you? There may be a reliable indy near you who would be a better bet than a dealer or garage unfamiliar with Citroen hydraulic engineering.
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Post by Xaccers »

There is no servo on Xantias, they have a dosuer valve which the brake pedal operates, allowing the hydraulic pressure to get to the calipers to apply the brakes :)

Did they mention where the leak was? Quite often normal garages see a bit of LHM on the top of the resevoir and presume it's leaking.

The metalic scraping noise will be pads against the discs.
Next time it happens, apply the handbrake slightly not the foot brake, and if it stops the sound then it's the front brakes causing the issue, if it doesn't then it's the backs.

If it's the backs, limescale like corrosion builds up between the arms and the calipers, making them sit at an angle.
Set the car on high, jack the rear subframe a bit and get axle stands under the jacking points on the sills, slacken the rear wheel bolts, set the car on low and remove the rear wheels.
Look over the top of the discs/calipers and check they are in line and not angled.
If they're angled you need to remove the calipers and chip the limescale off. Be careful as sometimes the caliper bolts can snap.
If you're careful you can clean them up without needing to undo the metal hydraulic pipe. Apply a liberal layer of grease to the mating surfaces to reduce the chance of future limescale build up.
It'd be worth bleeding the brakes too (engine running, suspension on high, helper with their foot on the brake pedal - no need to pump just depress it)

If it's the front, then it might be time to change the discs and pads, also the handbrake cable eventually lets water in and can start to stick.
Would also be an idea to bleed the front brakes too.
Make a note of the colour of the LHM that comes out. The brake lines are dead ends so will have the oldest LHM in them.
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Post by scooobydont »

Many thanks for the replies.

I am based in Stirling, Scotland.

I do not think the LHM has ever been changed. I bought the car 3 years ago with 22k on the clock (no service history). The colour of the LHM is yellow (definitely not green!).

I will follow the guide and get this flushed out and replaced.

I have found the guide for the ABS sensors (thanks!).

It's definitely the fronts that are scraping (disc and pads changed a year ago).

What is tick rate?

Thanks for the advise so far.
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Post by scooobydont »

Xac wrote:
Did they mention where the leak was? Quite often normal garages see a bit of LHM on the top of the resevoir and presume it's leaking.
I think that is exactly what has happened. The garage told me they thought it was do do with the servo as well! I think they took one look and went "we aint touching that".
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Post by Xaccers »

scooobydont wrote:
Xac wrote:
Did they mention where the leak was? Quite often normal garages see a bit of LHM on the top of the resevoir and presume it's leaking.
I think that is exactly what has happened. The garage told me they thought it was do do with the servo as well! I think they took one look and went "we aint touching that".
Definitely likely!

As for the tick rate, it's the pressure regulator kicking in.
At the front of the engine you'll have the accumulator sphere, this is an important sphere which often gets overlooked as it doesn't effect ride quality so not obvious when you need to change it.
It acts as a dampner on the pressure system absorbing any spikes, and also most importantly it's an emergency reserve of pressure for the brakes should your aux belt snap.
There's one at the back of the car, up in front of the spare wheel known as the anti-sink sphere which does the same for the rear brakes. If the front one needs changing then the back one will also most likely need replacing.

With the engine idling, open the bonnet and listen at the front for a tick/click sound form the regulator.
Anything over 30 seconds is considered good, a new accumulator sphere will have a tick rate of over a minute.

New spheres are around £22 each from GSF.
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Post by myglaren »

scooobydont wrote:
What is tick rate?
With the engine running and height achieved and stabilised if you listen at the front of the car you will hear a definite "Tick" at regular intervals, this is the pressure regulator cutting in and out.
With a fully charged accumulator the tick rate should be >30".
The faster the tick rate then the poorer the condition of the accumulator and the less pressure reserve in the system.

The accumulator is existentially a reserve for the brakes in the event of a system failure and allows several applications of the brakes before they become completely inoperative.

A poor accumulator also has negative effects on the rest of the system.
As it is some time since the system has been serviced it would be advisable to give it all a thorough check over and replace any spheres with reduced pressure - the difference in ride quality will amaze you.

ETA: Unaware of any good indy's in your area but some of the Scottish members may be able to point you in the right direction.
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Post by Xaccers »

Also while the car's idling, check the hydraulic pump for any leaks.
Look around the large nut with the metal pipe screwed into it, quite often the o-ring there goes.
It's pennies to replace and dead easy. There's a same sized blanking bolt further around the pump that uses the same o-ring and can also leak.
Where the bell end seals with the main pump (the bell end feeds to the steering), there's a large o-ring which can also leak.
If they are weeping, LHM eventually penetrates the alternator killing it.
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Post by andmcit »

re: scraping and tick rate

The hydraulic circuit is fed under massive pressure (1500psi) by a unique to
Citroen hydraulic pump that is constantly driven by the engine via the main
auxillary belt (that also drives the alternator) where a consitent stable level
of pressure is required and maintained by a pressure valve, monitored by a
pressure sensor.

When cycling the pump between high pressure fluid added to the circuit and
uneeded fluid diverted out back to the feed reservoir a valve cuts in and
out in a regular 'heartbeat' cycle irrespective of the speed the engine is
running - the tick sound is effectively a guide to the health of the hydraulic
system.

If the whole system is happy and running correctly the whir click and
whoosh of this cycle will be roughly at intervals of around 30 seconds or
thereabouts. If a tick is heard at very short intervals then it will require
fixing.

The pulse of high pressure into the circuit is damped and momentarily
stored by a cushion of gas in a sphere (similar to that found on the main
corner suspension units); this is called the regulator or accumulator sphere.

Renewal of this will significantly help reduce the strain on the hydraulic
circuit, where, if left unchecked can rupture weak points such as the pulse
of fluid to/from the reservoir. If run for a prolonged period with a flat sphere
the hydrulic pump will also feel the strain and this could very well be the
scraping sound that can be heard. Is the sound a harsh metal to metal
scrape or more like a bolt rubbing against a pulley etc?

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Post by scooobydont »

I have had more answers here than I could have imagined, seriously, thanks for every-ones input. I am off for the next 5 days so will be carrying out all of the above (where I can).

None of the things mentioned have been touched in my ownership. I put it in to the same local garage for servicing as well :(. I wish I had known that they hadn't got a clue a lot earlier.

I find it weird that there maybe several faults rather then just one. All these issues started within a week of each other. I guess one can have a knock on effect to another?
andmcit wrote: Is the sound a harsh metal to metal
scrape or more like a bolt rubbing against a pulley etc?

Andrew
Definitely metal on metal. It sounds like pads just catching on the discs.
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Post by Xaccers »

The brake scraping noise is most likely unrelated to the hydraulics.
The hydraulic stuff we've mentioned is general servicing/maintenance as we know what usually gets missed (even by Citroen dealer garages) and could have a knock on effect of the brake pedal going hard.
Another reason for the pedal going hard could be with the spring housing under it.

The brake pedal system is really simple, basically under the pedal is a button connected to the dosuer valve which opens it and allows the pressure to reach the brakes.
Between the pedal and the button, fixed to the underside of the pedal arm is a spring housing, it looks like two top hats joined together.
Inside is a spring, which gives the brakes a more conventional feel rather than the on/off that they could have.
Might be worth pulling this out of the pedal, it just sits in a cup on the back of the arm but can be quite tight, and seeing that it's squeezable.
Some people prefer the on/off brake action of older citroens so replace the spring with a similar length of 15mm copper pipe.

To depressurise the hydraulic system so you can remove spheres, idle the engine, set the car on low and let it run for a good 5 minutes to settle down.
Then with a 12mm spanner open the bleed screw on the regulator by the accumulator sphere, it's the only 12mm bolt head there, just open it enough to make it whistle as the air/lhm rushes back to the resevoir.
Then stop the engine and nip the bleed screw back up.

To remove the accumulator sphere, as with corner spheres, you'll probably need a sphere removal tool, or a strong chain wrench (strap wrenches may not be strong enough).
You can make a tool up following these instructions:
http://www.frenchcarforum.co.uk/forum/v ... hp?t=21850
Or you can buy one from ebay, but Pleiades sell the best type of tool.
You only need to slacken it enough to then be able to spin it off by hand.
The new sphere will come with a new o-ring, coat it in fresh LHM and fit it to the recess in the sphere socket on the regulator, then screw in the new sphere finger tight.

For the anti-sink sphere, you'll need a 9mm flare spanner, and a replacement pipe seal 4.5mm if memory serves.
From underneath (with the car up on axle stands like I mentioned in an earlier post, and depressorised) hook the spanner onto the nut on the end of the pipe into the A/S sphere.
Then unscrew the sphere (you may need the tool to start it off if it's rusted to it's socket).
With the flare spanner in place you'll screw the sphere out of it's socket and off the nut in one go :)
Even though it doesn't need it, the A/S comes with a new o-ring, use it! It will stop the sphere rusting to the socket.
Pop the new seal on the end of the pipe, start the sphere off enough to hold it in place, so one or two turns, fit the pipe into the hole in the sphere and start the nut going back into the sphere, then with the flare spanner in place screw the sphere home (again this will screw it onto the nut as well), then nip up the nut the last few turns it will need.
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Post by andmcit »

If the scraping stops when the brakes are applied then it could be pads down
to the backing plate just about to start damaging the disc as you'll definitely
know when the pad is shot when the sound gets promminent and won't go
away whatever you do and increases in severity upon braking.

I queried the sound as I have seen a Xantia where the accumulator sphere
was flat and the regulator was cosntantly clicking and the hydraulic system
was running flat out and one of the through bolts in the pump gave up and
was rattling against the driven pulley though not allowing the pump to leak
until another bolt failed with immediate pressure loss and hydraulic failure.

Just worth checking where the scraping is coming from; engine bay or wheel.

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Post by scooobydont »

Well just drove home from work, I checked for the tick and it is every 15-20secs. Looks like I have a good place to start anyway :).

The metallic scraping is also more noticeable when turning right.

That's me off for a week now (worked all xmas and new year), so will have plenty to keep me busy now.

Off to GSF in Glasgow in the morning I think! (handy I get 10% off as I am also a '72 beetle owner and get a club discount ;))

I will keep the thread updated.

Thanks again.
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Post by Xaccers »

CCC members also get a 10% discount, join both and see if you can double up :D
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Post by myglaren »

scooobydont wrote:Well just drove home from work, I checked for the tick and it is every 15-20secs. Looks like I have a good place to start anyway :).

The metallic scraping is also more noticeable when turning right.

That's me off for a week now (worked all xmas and new year), so will have plenty to keep me busy now.

Off to GSF in Glasgow in the morning I think! (handy I get 10% off as I am also a '72 beetle owner and get a club discount ;))

I will keep the thread updated.

Thanks again.
'Tight' handbrake cable most likely - corroded & seized.
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