Has anyone else had this?

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

Moderator: RichardW

Post Reply
rossnunn
Posts: 1254
Joined: 09 Aug 2003, 03:00
Location: Boston, Lincs
My Cars:
Contact:

Has anyone else had this?

Post by rossnunn »

I've had this a few times.
1.8 16v 1996 N Xantia.
Braking, you start to push the pedal the car starts to brake no worries, then its as if the car stops slowing down, so you go to push harder but nothing, pedal doesn't move so you mash it good & proper & head butt the windscreen.
I've has this like 7~10 times in the last 2 weeks, but not everytime I touch the brakes.
Just wondering if anyone has had similar? I've yet to check the LHM level.
I also got the stop light & temp warning light up on the dash the other day it was on for about 2 seconds then went out & not been back on since.
Image
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Hi Ross -

If you bother do a search on Xantia brakes - you could find loads on exactly this issue.

Its air in the front brakes.
Before commencing brakes bleeding - then do the Citaerobics to vent any air from the suspension - which could find its way to the rear brakes.
Now bleed the brakes - using 5m's of 5mm PVC hosing attached to the brake bleed nipples - leading directly to the reservoir.

Warning : do yourself a favour and work free the bleed nipples as first part of the project. Best to remove the nipples and grease with alupaste before refitting. Bleed patiently as there are some 4+4+4 meters of piping from pump feed out to rerar suspension - back to the doseur valve - and again out to the rear brakes.

The reason air in the front brakes does this is that the hydraulic pressure needs a finite time to compress the air - each time you press the pedal.
As the pedal is a "tap" for the hydraulic pressure to the brakes - and NOT a master valve transferring your foot pressure - then the brake pedal will NEVER warn you feeling spongy - as the wellknown air indicator in conventional brakes systems will do.
Anders (DK) - '90 BX16Image
rossnunn
Posts: 1254
Joined: 09 Aug 2003, 03:00
Location: Boston, Lincs
My Cars:
Contact:

Post by rossnunn »

Hi anders,

well I do read this board most nights & have read the threads on Xant's brakes, however I have not read anything on the line of what I'm experiancing or else I would have dragged up a old post from the depths.
Would air get into the system over time then? As wasn't like it when we got it & we've never done aything to brakes/suspension other than a visual inspection & a grease of the height corrector every MOT time. Its just been one of those very boringly reliable cars. We've not fitted any discs or pads in the last 2 MOT's, mainly becuase we don't do the mileage with it.
And if it was air would it not be the same everytime I touched the brake pedal?
Image
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Sorry -

yes air can get into the front brakes. Over time the pads & discs wear down - making the piston reach out longer. This in turn means more LHM to fill the caliper cavity.
You should do the standard checks for air in the system : pump feed hose tight over the studs, clamps tight, hose no surface hairline cracking.
Anders (DK) - '90 BX16Image
rossnunn
Posts: 1254
Joined: 09 Aug 2003, 03:00
Location: Boston, Lincs
My Cars:
Contact:

Post by rossnunn »

righty ho, I've got to ckeck the strut mounts on weds so I'll take a good look round while I'm there.
Image
citronut
Posts: 10937
Joined: 29 Apr 2005, 00:46
Location: United Kingdom east sussex
My Cars:
x 92

Post by citronut »

air dose get into the system as the spheres loose there gas over a period of time,check the regulator ticking(pulse) as maybe the reg sphere has dumpt its gas into the system
regards malcolm
jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00
Location: Hampshire, UK
My Cars:
x 2

Post by jeremy »

Strangely Xantias seem more prone to this problem than BX - and I suppose the reason is that the BX doesn't have anti-sink - and so when the suspension drops LHM is returned to the reservoir - automatic Citroebics!
jeremy
User avatar
Mandrake
Posts: 8618
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 666

Post by Mandrake »

jeremy wrote:Strangely Xantias seem more prone to this problem than BX - and I suppose the reason is that the BX doesn't have anti-sink - and so when the suspension drops LHM is returned to the reservoir - automatic Citroebics!
And in the case of rear brakes the anti-sink sphere itself is probably a major additional source of nitrogen bubbles that the BX didn't have...

Regards,
Simon
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
rossnunn
Posts: 1254
Joined: 09 Aug 2003, 03:00
Location: Boston, Lincs
My Cars:
Contact:

Post by rossnunn »

ok so if we're sure its air this point still needs answering:

And if it was air would it not be the same everytime I touched the brake pedal?

I have tried it make it do it in various runs, heavy braking, light fading into heavy braking, what ever I try I cannot make it do it consistantly.
Could this be because it might be a air lock or air 'bubble' in the LHM thats floating around the system??
Image
jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00
Location: Hampshire, UK
My Cars:
x 2

Post by jeremy »

probably better to substitute the word Gas for Air! - The likely source may be natural ageing of the accumulator, and it may be that you have moved the gas or it has now passed out of the system due to circulation.

Its probably worth testing the accumulator with the sit in the boot test. (car at normal height, engine running for a couple of minutes. Turn off engine and sit in the boot. car should drop a long way then after 30 seconds or so rise to its former height powered by the accumulator. Nice simple clean hands test.)
jeremy
rossnunn
Posts: 1254
Joined: 09 Aug 2003, 03:00
Location: Boston, Lincs
My Cars:
Contact:

Post by rossnunn »

LHM level in all postitions for some reason:

http://web.onetel.com/~glynnunn/ross/pics/lhm1.jpg

I tried the sit on boot lip test, sat there for about 5 mins & nothing happened, athough when I got off it did rise again.
I started the car & tried with the engine running, it dipped then rose back up again, got off, it rose higher then came back to a normal height.
Pump is ticking every 30 secs or so when in normal height.
When I lowered the car right down then back up using the leaver it to a while to come back up againit lifted the rear the front started to follow then kiinda bounced up to the right height.
Image
Post Reply