The non return ball valve is a simple 5 mm diameter ball bearing. I needed some many years ago for jaguar (Dunlop) disc brakes which used ball bearings to seal bleed nipples and found them in an motor cycle shop! Someone's got some in a junk box somewhere!
If you take the release screw out you should find that that ball is 7mm not 5mm.
Jeremy
CItroen BX hissing sound
Moderator: RichardW
Well, I did all that, the ball is in the right place, now, after i reconnected the PR, the car is still the same only it won't go down as fast as it used too when i turn off the engine, and the when I push on the back side of the car it bounces back up.
I noticed something while tightning the release valve: there is no hissing sound until I tighten the bolt and when I do it start the hissing and won't stop until I push the gas pedal and raise the rpm a little.
for some reason I start to believe that the cause of all this is the brake compensator, because every time i push the brake pedal, there is a pressure release sound coming from the pedal.
and also sometimes (rarely) when i push the brakes, the pedal starts pumping back and resisting me.
what do you think?
I noticed something while tightning the release valve: there is no hissing sound until I tighten the bolt and when I do it start the hissing and won't stop until I push the gas pedal and raise the rpm a little.
for some reason I start to believe that the cause of all this is the brake compensator, because every time i push the brake pedal, there is a pressure release sound coming from the pedal.
and also sometimes (rarely) when i push the brakes, the pedal starts pumping back and resisting me.
what do you think?
By the way, Mike, check this address I found: http://www.citroenz.com/forum/viewtopic ... 444aad978e
They say there how to overhaul the PR.
They say there how to overhaul the PR.
Simple way to eliminate the brake compensator is to drop the car - thwn all suspension and rear brakes are out of the circuit. if this makes no difference have a look at the return from the brake valve to the reservoir.
have you checked for air in the pump intake? Have you done your 'Citroebics? - raise and lower the car fully several times to expel air.
Rear part of the doseur can't be leaking that badly if it holds pressure long enough for the rear of the car to rise when you sit in the boot with the engine off! Many a good doseur has been thrown away through misdiagnosis and there seem to be some dodgy genuine ones around.
jeremy
have you checked for air in the pump intake? Have you done your 'Citroebics? - raise and lower the car fully several times to expel air.
Rear part of the doseur can't be leaking that badly if it holds pressure long enough for the rear of the car to rise when you sit in the boot with the engine off! Many a good doseur has been thrown away through misdiagnosis and there seem to be some dodgy genuine ones around.
jeremy
I had a near-constant "Hisser" too at one point - but never got round to resolving it satisfactorily as it was a car bought for temporary use and as a potential spares car.
However, I did go through the ball-reseating procedure and found that the click interval increased dramatically....until I touched the brake pedal for the first time. This, and the tests from the return pipes guide on the BX DIY site, helped me to the conclusion that the doseur valve was the culprit. The BX DIY site is definitely linked from www.citroenz.com, if you're not familiar with it.
This was a late-model BX (1993) and I gather from others that late BXs have had premature doseur failures.
In a private conversation recently, another forum member speculated that for late-model BXs the production tooling for this component, very sensitive to minor tolerances, could have become worn by the end of the BX production run, despite the changover to a modified doseur in 1987/8.
However, I did go through the ball-reseating procedure and found that the click interval increased dramatically....until I touched the brake pedal for the first time. This, and the tests from the return pipes guide on the BX DIY site, helped me to the conclusion that the doseur valve was the culprit. The BX DIY site is definitely linked from www.citroenz.com, if you're not familiar with it.
This was a late-model BX (1993) and I gather from others that late BXs have had premature doseur failures.
In a private conversation recently, another forum member speculated that for late-model BXs the production tooling for this component, very sensitive to minor tolerances, could have become worn by the end of the BX production run, despite the changover to a modified doseur in 1987/8.
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uhn113x
- Posts: 1161
- Joined: 06 Jan 2004, 22:06
- Location: Near Leeds, United Kingdom
- My Cars: 1981 Dyane - on road all year round.
1982 GSA Pallas - on road April - September.
1997 ZX 1.9D Dimension. - x 1
Right - I think we need to go back to first principles.
The hissing is caused by the regulator never achieving cutout pressure. There can only be three reasons for this:
1) The regulator cutout pressure is too high because of a fault (unlikely).
2) The pump output is insufficient - not too bad a job to swap it with one from a scrappy to check.
3) There is a drain on the pressure.
Tha latter could be checked by seeing what fluid is coming back through the various returns on the reservoir - there should not be very much. Check these and let us know if any are more than a trickle.
The only other places that pressure can be lost are in the power steering FDV and internally in the regulator.
The hissing is caused by the regulator never achieving cutout pressure. There can only be three reasons for this:
1) The regulator cutout pressure is too high because of a fault (unlikely).
2) The pump output is insufficient - not too bad a job to swap it with one from a scrappy to check.
3) There is a drain on the pressure.
Tha latter could be checked by seeing what fluid is coming back through the various returns on the reservoir - there should not be very much. Check these and let us know if any are more than a trickle.
The only other places that pressure can be lost are in the power steering FDV and internally in the regulator.
Hey there,
well, after cleaning the PR and returning it, the car won't sink so fast anymore and that's one good thing.[8D]
The hissing stopped for a 15 minutes drive but then returned (and now I do have a click after the hissing!).[^]
Now, I checked all return hoses at the entrance to the reservoir and none of them leak at all except for one that is leaking just a little bit.
I noticed that when I turn the steering wheel just a bit, the hissing stops.
well, after cleaning the PR and returning it, the car won't sink so fast anymore and that's one good thing.[8D]
The hissing stopped for a 15 minutes drive but then returned (and now I do have a click after the hissing!).[^]
Now, I checked all return hoses at the entrance to the reservoir and none of them leak at all except for one that is leaking just a little bit.
I noticed that when I turn the steering wheel just a bit, the hissing stops.
The hose you talk about should be the return from the PAS. With the steering relqaxed there is a small flow, turn the wheel and the valve shuts, and the FDV responds by increasing the flow to provide the assistance at the expense of the rest of the circuit. Well thats what its supposed to do. Sounds as though thats ok.
When you had the regulator off did you look under the pressure release screw? From the sound of it someone had been there before and I wonder if that ball has been lost?
Otherwise - is air getting in the pump supply?
Jeremy
When you had the regulator off did you look under the pressure release screw? From the sound of it someone had been there before and I wonder if that ball has been lost?
Otherwise - is air getting in the pump supply?
Jeremy
First check for air is to look in the reservoir with the car idling and see if there are any bubbles or a milky (green milk? - scary!) emulsion. What happens is that while the valves etc in the circuit are very good at sealing for oil which hasaa surface tension, they won't seal for air which does not - so problems are caused.
If you suspect air there are very few places it can get in - ie only between the reservoir and the pump inlet. take this hose off and look at its ends - do they look good. does the hose look sound or is it perished. as this hose is running at under atmospheric pressure air is drawn in and oil doesn't necessarily escape.
Anders suggests that if you are in the slightest doubt you simply substitute the rubber hose to the pump for a section of clean garden hose. If it makes a difference - you've found your problem.
Jeremy
If you suspect air there are very few places it can get in - ie only between the reservoir and the pump inlet. take this hose off and look at its ends - do they look good. does the hose look sound or is it perished. as this hose is running at under atmospheric pressure air is drawn in and oil doesn't necessarily escape.
Anders suggests that if you are in the slightest doubt you simply substitute the rubber hose to the pump for a section of clean garden hose. If it makes a difference - you've found your problem.
Jeremy