Xantia rear brakes Please read its a strange one............

BrianA · Post by **BrianA** » 10 Jun 2007, 14:03

fastandfurryous wrote:
Oh dear. Did he try to test the handbrake with the rear wheels in the rollers too?

No he told me as an advisory that they needed adjustment which I sort of knew.
This garage impressed me years ago as they managed to find faults that I knew were there on other cars that other so-called specialists could not.
It's a £20 re-test in 10 days so I'm going back rather than chance it at another garage.
But his understanding of Citroen hydraulics is apparently poor.
Bri.

jeremy · Post by **jeremy** » 10 Jun 2007, 14:04

I'm not sure its the tester's fault. From the failure cert I saw it seemed that they had to work in standard reasons for failure - giving references to the testers manual. The person who wrote the manual seems never to have seen anything other than a car on steel springs - which could be an increasingly serious problem with some of the systems used today.

Testers handbook here

http://www.motuk.co.uk/welcome.htm

Post by **CitroJim** » 11 Jun 2007, 07:51

BrianA wrote:But his understanding of Citroen hydraulics is apparently poor.
Bri.

It's not unusual. I find that hydro Citroens in general leave most garages with deeply furrowed brows. I always have my MOT done by an MOT-only place right opposite our indie Citroen Specialist in the belief that the MOT tester will have a chat with him if he has any doubts on something.

As a demonstration of the general difficulty of getting ones head around a Citroen, my Dad, who understands conventional cars inside-out and taught me all I know when I was younger, watched in a state of bewilderment as I did my rear calipers. Rubber seals on the hydraulic pipes? That was enough for him but when he asked if I wanted the brake pedal pumped whilst I bled them I collapsed in giggles. He was even more bewildered when I started the engine to bleed the brakes. And when green fluid came out, that really was too much for him.

If someone like Dad has a problem with it, there is very little hope for the average garage mechanic and of course, now with the youngest true hydro Citroens now 7 years old, things can only get worse

BrianA · Post by **BrianA** » 12 Jun 2007, 16:47

Goddamn

I've bled the rear brakes and now the back suspension either goes all the way up or all the way down it was working great before I did the brakes.
The height corrector is lubed and free like a new un.
Should I have gone front to back left to right?
The retest is tomorrow so it looks like I'll have to cancel for another couple of days unless you know better?
Cheers.
Bri.

AndersDK · Post by **AndersDK** » 12 Jun 2007, 23:57

Sure the little plastic link from the ARB has not simply popped off ?

BrianA · Post by **BrianA** » 13 Jun 2007, 05:38

Good morning AndersDK,
yes the plastic elbow is on and everything moves as it should.
When I bled the brakes with the engine running I found that I had to press the brake pedal to get the fluid to move whereas I was expecting the fluid to dribble out on its own accord.
I can only assume that this means that the rear accumulator is goosed.
I've left the car in high position overnight as I'm at work and later when I get up I'll run the engine whilst the car is in high for 10 mins to see if that cures it.
I put some of that thin plumbers tape around the flared pipe and then screwed the nut back in,that couldn't have caused any problems could it?

Ah well off home I go,walk the dogs a stiff whisky 6 hours kip and then back to the nightmare.
lol
Bri.

Mandrake · Post by **Mandrake** » 13 Jun 2007, 06:51

BrianA wrote:Good morning AndersDK,
yes the plastic elbow is on and everything moves as it should.
When I bled the brakes with the engine running I found that I had to press the brake pedal to get the fluid to move whereas I was expecting the fluid to dribble out on its own accord.

I don't understand how you would expect that ? Naturally you have to press the brake pedal for pressure to be supplied to the rear brakes

Unlike a normal car though you don't need to pump the pedal, just holding it down is fine - in fact I usually wedge a length of wood between the seat and the pedal when I'm bleeding the brakes on my own.

Regards,
Simon

Xaccers · Post by **Xaccers** » 13 Jun 2007, 09:28

You put PTFE tape around the pipe??

AndersDK · Post by **AndersDK** » 13 Jun 2007, 09:41

BrianA wrote:I put some of that thin plumbers tape around the flared pipe and then screwed the nut back in,that couldn't have caused any problems could it?

Brian -

I have to say this is an absolutely wrong approach working on Citroen hydraulics.

The threaded union nut does not in itself make the pipe join leak proof.
The union nut is only used to press in the flared pipe end - AND (most importantly) compress the rubber seal which then clamp against the pipe surface & the pipe bore inner surface. This way the pipe union is made leak proof.
Please forget ANYthing about waterpiping, plumbing, pressure airlines etc, as Citroen hydraulics deals with a working pressure of 170bar. This is about 20 times the normal pressure in anything else you know off. In fact only industrial hydraulic equipment really compares to it (albeit working with higher capacities).
You MUST leave the plumbing approach of thinking, when working on Citroen hydraulics. It can proove lethal to you or oher trafficants if you try repair the system piping using plumbing approaches.

Adding to Simon's advice you must be aware that :
1) the rear brakes will only work (have pressure to the master cylinder) if & when the rear suspension is loaded by the car's own weight (and/or goods in the trunk) - OR when full pressure on the rear suspension is forced by the full height setting on the manual lever.
2) when the wheels are dangling in the air, the HC will sense this like the car is in highest position possible (wheels farthest down from chassis - as if the car was set high standing on ground) thus closing off the pressure if height is set to normal.
3) the rear accumulator ('antisink sphere') has nothing to do with the rear brakes pressure as long as the engine (and thus pump) is running & supplying hydraulic pressure. Its only there to provise a reserve of rear brakes pressure during drive if the engine (and pump then) stalls. This accumulator sphere is rather amusing to remove as the pipe will twist if you try unwind the sphere, not removing the pipe first.

There is a very good technical guide written for Citroen newcomers here :
http://www.tramontana.co.hu/citroen/guide/guide.php

I recommand you download it, print it out and use it for self study. Its the best documentation that exists on Citroen hydraulics, passing on the technichal details, but still respecting that many readers may not be too technical inclined.

Post by **CitroJim** » 13 Jun 2007, 10:05

Looking back over this topic Brian,

Did you use the PTFE tape on the height corrector unions to fix the leak you had there?

If so, it is just possible a bit of the tape has come off and lodged inside the height corrector and is now stopping it working correctly.

Just to add, whenever you disturb any hydraulic unions always replace the rubber seal. They're very cheap from GSF and it is always a good scheme to hold a few of each size in stock.

Mandrake · Post by **Mandrake** » 13 Jun 2007, 10:11

citrojim wrote:Looking back over this topic Brian,

Did you use the PTFE tape on the height corrector unions to fix the leak you had there?

If so, it is just possible a bit of the tape has come off and lodged inside the height corrector and is now stopping it working correctly.

I know what he will have done - if the pipes have been removed from the height corrector, I bet the high pressure input and the return lines (the two right next to each other) have been reversed!!

This will cause positive feedback instead of negative feedback for the height correction! If the height is too high it will lift it right up, and if it is too low it will lower it right down. So it will end up either right up or right down.

Brian: if you use the manual height control lever and set it right up and right down, does the rear height work back to front ? If it does, reverse those two pipes again

Regards,
Simon

BrianA · Post by **BrianA** » 13 Jun 2007, 13:47

Thanks for your concern re the ptfe tape you lot.
I didn't take the pipes out nor did I replace the recommended seal with the tape I also didn't lose any fluid.
The unions themselves slid down the pipe after I slackened them off.
I just wound a bit round the thread and the pipe to slow down the tiny leak I was getting so as to placate the mot tester.
So the pipes aren't the wrong way round.
I got the impression from a thread I read that the fluid would leak out and I did eventually did do the brakes by jamming the pedal down.
As the fluid came down the pipe it was brown though it looked dark green in the bottle I bled it into so I guess I'm going to have to flush the whole system.
No animals were hurt in the making of this thread and now it's back to the car to see if I can sort the problem out again.
Thanks for all your replies.
Bri.

Xaccers · Post by **Xaccers** » 13 Jun 2007, 13:57

It may be worth while doing a hydroflush unless you've got a service history showing it and regular lhm changes have been done.

BrianA · Post by **BrianA** » 13 Jun 2007, 19:04

Xac wrote:It may be worth while doing a hydroflush unless you've got a service history showing it and regular lhm changes have been done.

NO service history.
The cars been stood for at least a year.
The Height corrector linkages were solid,the back end was stuck up in the air and as you know the brakes needed a good service.
The speedo says 77,569 miles and the engine is ever so quiet.
The air con works,it's ice cold and every switch on it operates the things that they're there for.
Other than strip down the height corrector and flush the system there's very little else to do to it.
I think the anti sink valve is buggered.
The car only cost £150 for a 98 Temptation2 so I can't really grumble.
Forgot to mention that it passed the MOT.

Post by **CitroJim** » 13 Jun 2007, 21:50

Bargain of the century Brian