pulsing brake pedal
Moderator: RichardW
pulsing brake pedal
the car is a 94 xantia td when the car has warmed up there is a pulsing sensation through the brake pedal when pressed hard.this gets worse the more the brakes are used.There are no problems with the suspension or power steering.this problem occurs when the car is stationary so it is not warped discs. any help please
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- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
I can't exactly remember what the timescale was with my Xantia between the spheres being replaced and the pedal pulsing stopping!, it may not have been immediate, so it may not actually have been the cause.
However, replacing spheres is the only hydraulic work I have ever had to do on my car and I know it had the fault before the sphere change, but it doesnt have it now. (nearly two years later) It could have been pure coincidence and it stopped on its own.
I have also heard of the brake doseur valve being blamed for this problem, so that would certainly be worth investigating if it persists.
Nick
However, replacing spheres is the only hydraulic work I have ever had to do on my car and I know it had the fault before the sphere change, but it doesnt have it now. (nearly two years later) It could have been pure coincidence and it stopped on its own.
I have also heard of the brake doseur valve being blamed for this problem, so that would certainly be worth investigating if it persists.
Nick
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- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
With the new sphere you can more or less be sure the high pressure delivery is constant.
A 94 model might have a seperate power steering circuit or a flow distributor, look at the pump, if there are two steel pipes coming from it the steering is seperate from the rest of the system.
Now there is a new accumulator sphere fitted, at what frequency (how often) is the regulator ticking, assuming the regulator is ok, a high cut in rate with a new sphere would suggest rapid pressure loss due to internal leakage.
You could disconnect the return pipes from the various components at the reservoir, look for pulsing in any of these, with and without the brakes applied.
At what sort of frequency does the pulsing occur, is it always the same or does it increase or decrease, especialy with engine speed.
Whats the condition of the LHM (is it still green) and filters.
From the suspensions lowest position to normal at tickover, how long does it take.
Does your car have anti lock brakes, I noticed a pulsing at times on car's that I test drove that had anti lock.
looks like we are looking for a worn component somewhere in the hydraulic system, the more info you can supply the better.
Dave
A 94 model might have a seperate power steering circuit or a flow distributor, look at the pump, if there are two steel pipes coming from it the steering is seperate from the rest of the system.
Now there is a new accumulator sphere fitted, at what frequency (how often) is the regulator ticking, assuming the regulator is ok, a high cut in rate with a new sphere would suggest rapid pressure loss due to internal leakage.
You could disconnect the return pipes from the various components at the reservoir, look for pulsing in any of these, with and without the brakes applied.
At what sort of frequency does the pulsing occur, is it always the same or does it increase or decrease, especialy with engine speed.
Whats the condition of the LHM (is it still green) and filters.
From the suspensions lowest position to normal at tickover, how long does it take.
Does your car have anti lock brakes, I noticed a pulsing at times on car's that I test drove that had anti lock.
looks like we are looking for a worn component somewhere in the hydraulic system, the more info you can supply the better.
Dave
Don't want to sound like the villiage idiot here, <img src=icon_smile_clown.gif border=0 align=middle>but does the car have ABS by any chance? And if so, is the ABS system working correctly or alternatively is there one wheel wanting to lock up?<img src=icon_smile_blackeye.gif border=0 align=middle>
Alan S
Alan S