Air getting into Xantia brakes

nridley · Post by **nridley** » 11 Mar 2005, 00:31

Air is getting into my brakes. Over the last ten days I have had all of my brake pads replaced, a new hydraulic pump and a new accumulator sphere. In the last couple of months I have had all of the spheres replaced and a new accumulator. After having the hydraulic pump replaced and the brakes fully bled the brakes were absolutely perfect. However, again, just two days later, the delay between pressing the brake pedal and the brakes kicking in is returning. It is definitely air in the system, but don't know where it is coming in. Any ideas?

AndersDK · Post by **AndersDK** » 11 Mar 2005, 00:51

As the pads and discs gets worn, LHM from the reservoir are filled out the caliper to take up the slack over time. This could bring in "air" with the LHM from other points in the system - like a slowly leaking sphere.
Also the HP pump feed hose could be leaking. As this is on the pump'as suction side, you wont see a fluid leak from here. Insted air is taken in.
Inspect the feed hose for general surface/hairline cracking - especially overe the studs both ends. Make sure the hose clamps both ends hold the hose tight.

tonespeed1999 · Post by **tonespeed1999** » 11 Mar 2005, 00:58

ive had a few customers complain of brake delay and brake pedal kicking back!
its a case of check hoses, pipes etc.bleed brakes and the suspension.
some times the problem does re-occur!

nridley · Post by **nridley** » 11 Mar 2005, 04:14

Worth adding - I currently am running with hydraflush and not LHM. Was told to run it for 3000 - 6000 miles and then drain the system and replace with LHM. Would this make a difference?!

nridley · Post by **nridley** » 11 Mar 2005, 04:23

Just to add - as I cannot seem to sort the problem (it has been to Citroen specialist several times) and I am a high mileage driver I am considering selling the car. Shame as the brakes are the only problem as everything else is immaculate. Was considering getting a Peugeot 405 instead as I like the diesel engines. Does anyone think it is worth persuing the Xantia air problem considering this month I have paid out £160 brakes & accumulator sphere, £100 spheres, £170 hydraulic pump, £40 MOT, £90 tax...£5.2million in diesel....
I'm just getting so annoyed as I like the car but throwing money at it is not resolving the one and only issue - the car does not like stopping! Maybe I should just leave a slightly larger gap on the M4....

dan.2cv · Post by **dan.2cv** » 11 Mar 2005, 04:38

Get it fixed and keep it, you've already spent a fortune and you'll end up with a great car. I'd start by bleeding it all again.

jeremy · Post by **jeremy** » 11 Mar 2005, 04:56

Really you can divide the hydraulic system into 2 parts - the circulating part and the limbs going to the brake cylinders which are of course one way only. Gas can only bet in from a leaking sphere or through the pump/reservoir system and if it does generally it can be expelled by citroebics.
So do Citroebics first thing in the morning improve things? Is there any air returning to the reservoir? have you examined the reservoir/pump hose and its connections?
Sounds like something very simple and cheap to cure.
jeremy

Homer · Post by **Homer** » 11 Mar 2005, 13:44

Are you sure it is air and not the brake valve (what would be the master cylinder on a conventional system) which neads an overhaul or replacement?

mark_sp · Post by **mark_sp** » 11 Mar 2005, 14:20

First I hope your not serious about selling a car with duff brakes as a woking car.
Second I do sympathise as I am experiencing a similar problem with my 1998 TD. Lovely car bought for £3K 2 years ago. Problem is I've spent almost as much again keeping it on the road, spent £240 2 days ago and now it needs another £180.
If my car was the age yours is I'd have no hesitation in stripping off the recently fitted parts, scrapping whats left and buying a working vehicle.
Mark

Kowalski · Post by **Kowalski** » 11 Mar 2005, 14:32

What is your accumulator sphere like?
If the accumulator sphere is flat it can cause delays in the brakes, i.e. no or little brakes when you first press the pedal, then the brakes come in hard.

jeremy · Post by **jeremy** » 11 Mar 2005, 14:36

I appreciate that you have had a new accumulator. What is the regulator tick rate? (should be 30 secs or more)
jeremy

PeterMann · Post by **PeterMann** » 11 Mar 2005, 18:01

The most likely place for air to be entering the hydraulics is the rubber suction line between the bottom of the reservior and the pump inlet. Easily fixed yourself. They usually crack at a bend, or where they are stretched to fit over the nipple of the pump, and this can be hard to find visually. I sometimes fit a short length of translucent nylon into the suction line, so you can see the air bubbles shooting past when they are being drawn in upstream of the pump inlet. After this is sorted, just bleed the brakes and she should be like new again.

nridley · Post by **nridley** » 12 Mar 2005, 01:35

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

I appreciate that you have had a new accumulator. What is the regulator tick rate? (should be 30 secs or more)
jeremy
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Sorry Jeremy - I'm not quite as advanced with my knowledge of Citroens! When you say tick rate, do you mean everytime the accumulator makes a quick noise? If that is the case then I think it is more than 30 seconds, but will double check tomorrow.
Thanks for everyone's advice on here. I will look at it all tomorrow and post a note back to let you know how I got along. I'm going to try and fix it - for the money there is no way I could get a car in such good condition or with so many 'extras' as my Xantia. I must say, however, it doesn't appear to have got any worse today so I will bleed the brakes again tomorrow and see how that goes.
By the way, this is a superb forum. Thanks everyone.

jeremy · Post by **jeremy** » 12 Mar 2005, 13:39

As your Xantia has the anti sink mechanism it will have a 2 outlet pump. This actually means that there are only 2 pistons pumping for the suspension and brakes. In turn this means that the system is more reliant on the accumulator for its function. In turn it is possible that an internal leak in the regulator or elsewhere reduces the efficiency of the accumulator. Such an internal leak would show up as rapid ticking of the regulator - a relatively easy and comprehensive check.
If it is ticking too frequently its probably the non-return valve under the accumulator sphere and can probably be re-seated free of charge! - search for instructions - they may be in the tips and tricks section.
Jeremy

nridley · Post by **nridley** » 12 Mar 2005, 14:06

Not sure mine does have the anti-sink mechanism...it doesn't stay on normal suspension when stationary if that is what you mean. I will have a look into the regulator this morning and let you know.