CItroen BX hissing sound

[wonderd]

Well, that's it for this topic I guess,
maybe I will throw the car over a clif somewhere..
the last thing I am going to try is replacing the accumolator and after that if that doesnt work........bye bye car.

[tomsheppard]

It means that at idle, you never get enough pressure in the system to fully fill the accumulator.
Possible causes?
Loose drive belt
Porous/leaky pipe to pump
(Easy faults)
Low output pump
Duff regulator.
(Difficult faults.)

[wonderd]

Thanks, but I checked all that, the belt is not loose and the pump is not leaking.
(even though there is some strange leak in the connection of one of the return hoses with the reservoir that I can't stop for some reason).
I relocated the ball in the accumulator.
there is no leak at the back of the car.
the oil in the reservoir is clean.
I imagine that the pump is giving enough pressure because it stops for 2 seconds when the engine is running above 13000rpm's, which means that there is a pressure leak or duff accumulator.
that is all I managed to understand from all the above messages.
Am I wrong?

[kitchD6C]

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.

On a crusade to find info on this topic, but while I was here I spotted this and felt I needed to add that there's a 4th option:

4) Blocked/collapsed filters in the FDV can cause the regulator to never reach pressure at tickover, too. Guessing it's starving it of flow, so kinda creating the same situation as a weak pump.

Anyway, as you were (nearly 20 years ago - I'd only just bought the BX 16v I'm currently working on when this was posted)