I have noticed that my 1993 Xantia TD has developed a brief pause between application of the brake pedal and actually feeling the brakes kick in. During the lull, I panic and depress the pedal further and then the brakes activate and the car skids dramatically.
I have been told it is either the accumulator or the doseur valve. I need to know which to try first. Please please help.
GUY
Xantia - Brake failure
Moderator: RichardW
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Dave Burns
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This is probably down to air in the brake lines, give them a good bleed, when bleeding the rear brakes the suspension needs to be on maximum.
Check the LHM level is not low (especially while bleeding) and check the pump intake pipe for secure connections, this one of the points where the air gets in, check the pump for leaks at the shaft behind the pulley its another area for air ingress.
If all is ok the air (nitrogen gas) can come from the spheres themselves, either naturally or by membrane failure, the latter if the problem comes about all at once.
The accumulator tick interval is used as a general guide as to its condition but is not a gauranteed foolproof method of diagnosis, it ideally doesn't want to be much less than 30 sec's.
Dave
Check the LHM level is not low (especially while bleeding) and check the pump intake pipe for secure connections, this one of the points where the air gets in, check the pump for leaks at the shaft behind the pulley its another area for air ingress.
If all is ok the air (nitrogen gas) can come from the spheres themselves, either naturally or by membrane failure, the latter if the problem comes about all at once.
The accumulator tick interval is used as a general guide as to its condition but is not a gauranteed foolproof method of diagnosis, it ideally doesn't want to be much less than 30 sec's.
Dave
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Kowalski
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Ex 97 Xantia 1.9TD SX 144k
Ex 94 Xantia Dimension 1.9TD 199k
If you've got a flat (or very near flat) accumulator sphere it accumulates enough pressure to keep the pressure regulator happy, but as soon as any part of the system demands pressure e.g. the brakes, the accumulator empties instantly and you'll have no pressure whatsoever, the brakes take what little pressure is available which isn't enough to do any braking. The system will re-pressurise itself, which takes a little time, i.e. it doesn't happen instantly.
I had this happening on my '95 when the rear height corrector stuck and I had no rear suspenision height. The lack of rear suspension height meant no pressure in the anti-sink sphere, and it exposed the fact that the accumulator sphere was flat. After I replaced the sphere and sorted out the rear suspension height problem all was well again.
So, check your accumulator sphere, and check your rear suspension height, if they're both OK, it may be air as Dave Burns has suggested above.
I had this happening on my '95 when the rear height corrector stuck and I had no rear suspenision height. The lack of rear suspension height meant no pressure in the anti-sink sphere, and it exposed the fact that the accumulator sphere was flat. After I replaced the sphere and sorted out the rear suspension height problem all was well again.
So, check your accumulator sphere, and check your rear suspension height, if they're both OK, it may be air as Dave Burns has suggested above.