Brake valve and Stiffness regulators, Losing pressure, erratic suspension

[Jan-hendrik]

As some of you may remember reading I had the SC/MAC sphere replaced because I thought it had lost pressure and was the reason the car sank quickly. The replacement resulted in some improvement: the car rose up faster after short and prolonged (overnight) standstill.
The next thing I decided to undertake was cleaning the hydraulic system with Hydraurincage. Almost immediately the trouble started. Braking, driving over rough road surfaces, taking a curve at some speed would stiffen up both front and rear suspensions accompanied by distinct clacking noises from underneath the vehicle. I recognize these sounds as emanating from the regulators. I am pretty sure the electronics are in good order. I presume the cause to be loss of pressure which closes the hydraulic valves inside the regulators. Continuing to drive on a smooth surface things return to normal, smooth suspension.
I checked the return tubes to the LHM reservoir and noticed quite a bit of leak back from tube #3, which is the one from the brake valve. There is a constant drip at a rate of at least 2 drops per second.
Could it be the doseur already WAS leaky before I replaced the SC/MAC sphere and the problem exacerbated by the cleansing action of the Hydraurincage?

This post has been edited by Jan-hendrik on August 17, 2011 01:39 am

[kenhall1202]

Hi Jan,

Leakage from the brake doseur is normal (witness the oft previously reported mess made in the scuttle area when the rubber end button perishes and splits on LHD cars). I have seen somewhere a figure for the upper limit of what is an acceptable leakage rate, but can't lay my hands on it (may have been about 4ml/min). All I know for certain is that I measured mine in January 2006 (on LHM) at 2.5ml/minute and that was within the limit. Depending on how you define a 'drop' volume (say 1/20 ml, your leakage rate on Hydraurincage could be about 6ml/minute. This rate may be less on LHM depending on the relative viscosities of LHM and Hydraurincage.

Citroen (did?) sell the seals and rubber end button for overhauling the doseur valve and I have the w/s manual instructions if you require them.

Ken

This post has been edited by kenhall1202 on August 17, 2011 12:00 pm

[Jan-hendrik]

Thank you, Ken, for your response. I do have the w/s instructions for the overhaul of the brake valve, but I think I'll ride out the few months with the Hydraurincage in and then see what happens when the LHM is back in.

I was just wondering if anyone had experienced the erratic behaviour of the suspension with the flushing oil in.

[Dieselman]

QUOTE (Jan-hendrik @ August 17, 2011 10:46 pm) 

Thank you, Ken, for your response. I do have the w/s instructions for the overhaul of the brake valve, but I think I'll ride out the few months with the Hydraurincage in and then see what happens when the LHM is back in.

I was just wondering if anyone had experienced the erratic behaviour of the suspension with the flushing oil in.

No, but the system does seem smoother now it's on LHM+ again.

I suspect your problem is just low hydraulics pressure caused by a worn out regulator spring.
Check the system pressure is at 175Bar cut out, 145 Bar cut in.

[Jan-hendrik]

QUOTE

I suspect your problem is just low hydraulics pressure caused by a worn out regulator spring.
Check the system pressure is at 175Bar cut out, 145 Bar cut in.

You might be right.
Now where is my pressure gauge and adapter set? Oh yeah, I sold it when I sold my DS 15 years ago thinking I would never need those things again

[Jan-hendrik]

Hmmm. Still confused. The cut in/cut out may be off, but that still does not explain the quick sinking, meaning pressure loss. The electro valves are not leaking.

[Jan-hendrik]

The quick sinking and erratic suspension behaviour was definitely due to the hydraflush combined with high ambient temperatures (30 to 35 degrees for months). I am back on LHM now and the problems are gone.
In hindsight I can also say that the hydraflush treatment was unnecessary. There was virtually no dirt in the filters and reservoir

[Jan-hendrik]

Well, after about a year the old symptoms are back. Quick sinking of the front of the car and the clack-clack from the rear regulator when driving.
I checked the leak back from the brake valve again and found it drips at a rate of 140 drops per minute (LHM) which would be about 7 ml. Could that be the cause of the quick sinking? I am going to replace the HP regulator and its sphere first and see if that cures the rear regulator fault.
Is there a way to test the front anti sink valve (SC/MAC) ?
I read somewhere not so long ago about someone who replaced that valve and claimed it cured the front end sinking. Can't find this post now
Your comments are welcome.

This post has been edited by Jan-hendrik on September 26, 2012 10:12 pm

[Jan-hendrik]

Well, I had the HP regulator replaced and a new accumulator sphere, a grey one, fitted on October 19. The accumulator sphere had only 22 bar left and that is insufficient. The suspension idiosyncrasies have gone and the front of the car sinks only very slowly Problems solved - for now

[robertmnorton]

Hi Jan, hope it's a long term fix. Citroen issued a notice that once stocks of old spheres were depleted grey coloured would be supplied in line with EU gas colour coding, not i think mandatory for gas charged vessels, green i think is acetylene and grey of course nitrogen C5's and C6's had grey spheres from the outset, the colour having nothing to do with the fluid type. At least you know they are genuine Citroen parts as after market suppliers seem not to have depleted stocks yet.
robertm

[miguels]

Hi Kenhall.
Sorry to disturb you.
Could you please send me the instructions for overhauling the Brake Doseur Valve?

Kind regards from Portugal.


Miguels

[Jan-hendrik]

Unfortunately I am no longer active on this forum, but the attached document may be useful for you

This post has been edited by Jan-hendrik on September 06, 2021 01:30 am