Regulator return rate - or - whats knackered now?

[Stinkwheel]

OK, so some of you folks will be aware of the sudden ish loss of LHM as witnessed at stratford sunday morning on the red TZD estate.
Fault tracked down to a dodgy Y piece under the battery area where the regulator return had come adrift slightly. I plugged the dodgy split end and have run a temporary clear tube to the reservoir from just the regulator leak back.

Unfortunately i can now see how huge the regulator leak back is, its FAR too much.

Can anyone clever tell me why this may be? Im wondering brake dosier internal leakage as ive heard of this before? Would there be any other reasons?

The regulator tick is about 6 seconds even with a new accumulator sphere fitted.

[Way2go]

If you have isolated the return from the regulator to the tank, there is no way you can blame the doseur (which is mounted on the bulkhead).

It sounds like the seals/valves in the regulator have "let go" and you will therefore need to replace or renovate. If a service kit is still available I'm sure someone will tell you shortly and from who.

[Stinkwheel]

See, now thats logical thinking. Although......

Surely its logical to say that if the brake doseur is leaky internally (which i can believe due to 310k mileage of the car) then the accumulator/regulator has to work harder to keep up with the pressure needed by the internally leaky brake valve - thus, it is itself cutting in and out more hence flowing more return than a normal healthy system?

Would that follow? In my mind it does, i can be wrong though, Im happy to be proved so, but i just wondered if anyone had similar experiences to share.

[Dollywobbler]

Wouldn't a faulty doseur cause other faults though? The back end doesn't seem to drop at an alarming rate, which can often be doseur related.

[Stinkwheel]

Wouldn't a faulty doseur cause other faults though? The back end doesn't seem to drop at an alarming rate, which can often be doseur related.

See, now i think it does drop quite quickly. I can park and leave for 3 hours and the back is on the floor yet the front is still at ride height.

[Vanny]

Wouldn't a faulty doseur cause other faults though? The back end doesn't seem to drop at an alarming rate, which can often be doseur related.

See, now i think it does drop quite quickly. I can park and leave for 3 hours and the back is on the floor yet the front is still at ride height.

It's not the parked up sinking so much as the sinking under breaking. I have a shot doseur valve, and in breaking from 30mph to zero, the back end has to recover a lost 2" of height once stationary. Once parked, the rear can stay up for up to 10 hours, so it's not immediately obvious where the fault lies.

[citronut]

have you re/seated your balls, whoooops i mean ball bearing behind the regulator bleed screw yet,

as this not seating clean can cause your excessive tick rate,

which i suspect could also cause more return flow

regards malcolm

[Stinkwheel]

Fair enough, thanks Vanny, i hadnt appreciated this, it doesnt drop under breaking really, so possibly rules out the brake valve.

I shall investigate further, probably by swapping out the whole regulator for another and see what occurs. Mainly because i have one that i know is good and it doesnt cost anything but time to try it out.

Malcolm, I havent as yet. To do it in situ on the TZD really needs the radiator off or the regulator removing, which means i may as well just swap the whole known good unit i have in for now, then try the re-seat ball trick on it when its off the car and becomes, hopefully, the reserve unit.

[RobC]

I thought the back end was meant to sink under braking... That's the built-in anti dive working that Citroen was so proud of in the literature when the BX was released. It does this because the rear brakes are fed off the rear suspension pressure. Stand to be corrected of course,

I have a brand new brake doseur and it sinks at the back (not loads but noticeably) when you have your foot on the pedal at traffic lights for example, then shoots back up when you take it off (before quickly settling to the correct height).

[saintjamesy89]

Not worth much perhaps, but my understanding was that a leaking doseur meant that the rear end lost pressure when the system wasn't running, so it sinks over time when parked - mine is on it's bump stops at the back after 2 hours or so. Also, when I brake, the back end noticeably rises, much more so than the transfer of the center of gravity to the front and loss of speed would produce on there own (i.e under
braking).
Just this morning I was followed rather closely by a brand new black Audi, so much so (surprisingly) that I tapped the brakes a few times over a couple of seconds, each tap made the spoiler move up the Audi's grille in the mirror. The bulkhead area on my TXD is also very well covered in LHM, some even makes it to the floor - I had put this down to the doseur (front HC already sorted). Could a leaking doseur send pressure to the rear suspension circuit, creating a temporary rise? Or could it be that as this TXD has 16 spheres (55 bar)), it's just so soft it wallows about so.

[Vanny]

That's the built-in anti dive working that Citroen was so proud of

Citroen BS at it's finest i reckon. Anti DIVE would be stopping the front of the car going down under braking, no? And i'd have thought this is because the suspension auto magically pumps its self back up and the load increases.

I'd agree that they all 'sag' a little at the back under braking, but it should be un noticeable without paying attention. In my case you go from having floor int he rear view mirror to having the windscreen of the car in front, its dreadful and the Doc can attest to!

[citronut]

a hydraulic citroen with everything functioning as it is meant to, should sit down on breaking, not one end or the other but both end

regards malcolm

[Thread Bear]

I had this happen directly after mucking up the rebuild of the rear height adjuster. With the T piece in question going, then the U bend pipe that feeds into it. So my prob was self inflicted and resolved. No expert on hydraulics but a droopy rear might be height adjuster fouled up with crud? Mine was full of it, like dust when dry. Presumably it can lodge a valve open so it weeps pressure away.

My car is noticeable for a bit of rear dive. Since it works at the moment I will leave a full investigation for another time.

[Dollywobbler]

Just this morning I was followed rather closely by a brand new black Audi, so much so (surprisingly) that I tapped the brakes a few times over a couple of seconds.

Wrong response. You own an XUD turbo. I find hitting the throttle is more likely to cause a tailgater to back off, when they start choking on soot!

[Stinkwheel]

Just this morning I was followed rather closely by a brand new black Audi, so much so (surprisingly) that I tapped the brakes a few times over a couple of seconds.

Wrong response. You own an XUD turbo. I find hitting the throttle is more likely to cause a tailgater to back off, when they start choking on soot!

Certainly true of the red one