Xantia Brake problems

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
philhoward

Xantia Brake problems

Post by philhoward »

My Xantia TD had a problem since I bought it in November with the brakes; they woudl apply fine for 3-4 seconds on a good hard brake, than appear to "back off", then re-apply. If slowing off a motorway, this would happen again every second or so until foot removed from brake pedal. I posted some time back on posible problems; it seemed at the time that the acc sphere would be the likely culprit. Took it back to the dealer I got it from, he replaced the acc sphere.
Now...the brake problem was a lot better for a few days, but has now returned with a vengance, same as before. The anti-sink no-longer works, either! Has he buggered it up totally, and any ideas what to try next? He's likely to be asked for a full refund at this rate.
Could it be the doseur valve playing up, or a lack of flow from the pump?
It's a 95M Xantia LX TD, Anti-sink, but no ABS.
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

PhilH -
First of all try Citaerobics :
http://citroenz.com/forum/viewtopic.php?t=42
Then suspect the "springy thingy" connecting the pedal to brake valve.
I don't think you should turn any vengeance against your mechanic. It's a lot more easy to sort things out being polite & friendly - often you even get a lot better service then [8)]
philhoward

Post by philhoward »

Have tried the Citaerobics...no improvement at all.
What's the "springy thing"? Would that just cause the sticking, not the pulsing?
Unfortunately he's not my mechanic (I am!); he's just the (small) dealer I bought the car off who does most of the jobs himself, and hasn't got much knowledge. I know more about Citroens than he does, it appears...
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

It's the spring connection between pedal & valve - to make the hydraulic Citroen brake pedal appear as a "normal" car.
If the spring is weak - broken in it's coil - it can cause the pulsating effect.
But so can any air in the brake lines - then most likely the rear brakes circuit as it's feeded off the rear suspension pressure.
Note that the term "air" is likely to be N-gas from a leaking sphere.
The N-gas under pressure is approx 0.4L new sphere - but in free air this amount to approx 32L of volume. This means a tiny leak can go on for months before the sphere is actually flat.
Does the new acc sphere in fact looks like a brand new one ?
The click interval between the charge cycles from the pressure regulator should be in the 2 min's range with suspension on low setting - cutting off any leaks in the suspension.
This indicates a good acc sphere.
If the click interval is more rapid with suspension in normal height - you most likely have a leaking brake valve.
Cheapest option for your "mechanic" would be a swap from any breakers car - or a "re-newed" sphere - which could well go flat again within days.
Being your own mechanic is not always an advantage - as you often have to let a lot of exact knowledge stay in your mind - never let it leave your lips - if you discuss with garages [:D][:D][:D]
But then again - don't try make money repairing cars with this knowledge. You'd simply be too slow - out of your own interests doing things right [;)]
philhoward

Post by philhoward »

Anders,
Thanks for the pointers so far. I'll take another look at the acc sphere tomorrow (too dark and wet now).
Would the leaky sphere (apparently all 4 corners were replaced less than 2 years ago) or the broken coil give a pulsating effect of the frequency I experience (3-4 seconds before first felt, then every 1 second)?
This is on a steady constant braking from 60-70mph; firm but not heavy. BTW, If i brake very lightly, it doesn't do it at all...
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Donno on the pulsating interval -
No owners have thought of timing this - just reported the pulsating effect.
If you suspect the ABS butting in when it should not - then you can't miss it - as the ABS function clearly feels violent and scaringly on the pedal - at a fast hammering rate.
philhoward

Post by philhoward »

It doesn't have ABS...
It's like the pressure has run out, so the brakes come off for an instant (1/3 of a second?), then reapply, almost like warped discs, but in reverse; it does it more regularly the longer you brake (and hence the slower I get).
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

That definately points to either a dodgy acc sphere - or a dodgy brake valve.
philhoward

Post by philhoward »

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH!!!
Just thought I'd try the Citareobics again, to find the STOP light coming on as I went from low to high, to always on at high.
I KNOW I topped the fluid up after the acc sphere was changed (100 miles ago), but I've found the cause of all my problems...
...a bloody huge puddle under the Nearside (Left) Rear suspension Ram unit. It's at the front, so obviously NOT the sphere seal[V][V]
Any ideas of an OUCH cost?
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

PhilH -
This is exactly where DIY comes in to save you £££'s [:p]
It's not a complicated job - but takes time to bugger with rusty bits etc.
GSF stock cylinders.
Pleiades stock the pipes - and also the cylinders and any thinkable accessory for hydraulic Citroens.
Post Reply