jgra1 wrote:but the car still feels the same
and now it tends stay down at the back.. if you put it on high and then on normal it lowers to correct height, but doesnt come up from down? - i can live with this..
This is nothing to do with air in the brake lines... its something to do with the movement of the height corrector linkage at the rear, as I think was discussed in another thread. Most likely the linkage is a bit corroded and slightly seized.
so, the main symptons, :
the brakes still feel odd, the pedal pulses, the brake control valve hisses as it pressurises and depressurises, the front dives a lot, there is a small chance the hydraulic pump may have a leak but I need to confirm this..
The brake control valve hissing (more of a slurping noise) when you release it after pressing it hard is normal. Pedal pulsing is not normal though.
First of all you want to confirm that its not being caused by a misbehaving ABS system - simply find and unplug the ABS computer fuse and go for a drive and see if it still pulses the pedal. (If you got the right fuse the ABS warning light should be on continously on the dash)
If it no longer pulses you know you have an ABS problem like an intermitant sensor wire - I had a problem with the front right sensor on mine which made the brakes behave strangely at low speeds around 10Km/hr - sometimes pulsing/chattering the brake pedal when pulling up to a stop.
Occasionally the ABS warning light would come on while driving too. After I fixed it I havn't had any more occurances of the chattering brake pedal at low speeds.
If you still get the pedal pulsing, you know the ABS is not to blame, so put the fuse back in.
One thing that you could try which worked for someone else (see near the bottom of the thread "terrible xantia brakes" which talked about the pedal spring) was to simply run the car until pressurized, turn off the engine, and sit there fully depressing and releasing the brake pedal until all the stored pressure is used up. (This can take a LOT of depressions, approx 50, you know when the pressure is gone when the pedal starts to go limp)
We still don't understand how this worked, but we suspect he had an air bubble trapped in the brake control valve itself which was difficult to dislodge.
As for the nose dive - are you sure its the front diving, or is it the rear lifting ? If its the rear lifting it means the rear brakes are not biting as well as they should (pad/disc surfaces, or pistons that need freeing) while if the front dives excessively it could mean the FRONT brakes are not biting as well as they should.
Could it be the pump isnt outputting enough, Shall i take it off and renew seals?
Could it be the brake control valve?
there seems to be no air in system,
the accumulator is new
Well if you didnt find any air in the system at all, the seals in the pump are probably ok. If they weren't it would be allowing air into the system, (for seals on the suction side) or causing an obvious oil leak. (For seals on the pressure output side)
Regards,
Simon