frequency of pressure regulator ticks

freek · Unread post by **freek** » 03 Nov 2004, 00:08

Hi,
I wonder how sound the hydraulic system of my BX trd turbo is. Fact is that the interval of the pressure regulator ticks is about 15 seconds. I read that this must be about 60 seconds or so. I also noticed that the powersteering sometimes has a lack of pressure. The first suspect, namely the main accumulator sphere is OK: a refill yesterday resulted in an increase from every 10 seconds to the mensioned 15 seconds. The suspension spheres are in perfect shape (as is the suspension). The flow divider is new. My conclusion is: there must be an excessive pressure loss somewehere in the system or the regulator itself is faulty. I don't suspect the pump, because it is able to rise the car to the drive position from the lowest in about 10 seconds. . Does anyone know what is normally the cause of these symptoms or how I can test the system on a BX which has run more than 400.000 kms. Thanks!

AndersDK · Unread post by **AndersDK** » 03 Nov 2004, 00:39

Do a simple test :
Have engine idle - handbrakes on - suspension to LOWEST height.
Now check the click interval again.
I suspect it will go up in the minutes range.
If that is true - then the front suspension cylinders (struts) are leaking out the pressure in the overflow return rubber hoses (the 2 hoses seen on the strut inside wheel arch).
This is a typical and very common BX problem.
You may simply unplug these hoses into a jar for flow test. Raise the suspension to normal height for test. There should be no flow.

freek · Unread post by **freek** » 03 Nov 2004, 02:12

Thank you Anders for your reply. Unfortunately the result of your test is negative: the interval time did not increase. So the conclusion is that the suspension struts are not verdict. What should be the next step?

AndersDK · Unread post by **AndersDK** » 03 Nov 2004, 02:53

Absolutely sure the suspension was set to LOW ? - and the car sunk down on it's knees ?
Hmmmm....
The servo steering is not connected to the regulator output with it's accumulator sphere, but directly to the pump.
This means that the servo does not drain the accumulator sphere causing fast clicking.
The fact that the regulator is clicking - directly points to a good pump, as the click is produced by an upper pressure of approx 170bar - never possible with a defective pump.
This concludes that the problem must be in either of 3 areas :
1) suspension
2) brakes doseur (master or pedal) valve
3) the regulator itself
You have already tested the suspension good - leaves us with option 2 + 3.
Since your car is a LHD - you will have a black plastic return hose from the brake valve - the one that runs in to the rubber and comes out connecting to the reservoir. You also have a rubber return hose coming from underside of the brake valve - which is the one the plastic hose connects to.
These are the working returns from the brake valve - meaning there should be flow here ONLY when you release the pedal after applying brakes.
Logic says that if you by testing find flow here NOT TOUCHING THE BRAKE PEDAL - the brake valve is then the problem.
- another known problem to the BX.
If you still dont find any flow - you're left with the regulator itself.
Check that the pressure relif valve screw on the regulator is closed (the 12mm bolthead) - but it must not be torqued.
If the regulator seems to be the problem - then 2 common problems are described here :
Overhauling the PR

jeremy · Unread post by **jeremy** » 03 Nov 2004, 04:17

All that has been said before is true but from the sound of what you are saying the regulator non-return valve needs re-seating.
there are 3 ways fluid can escape from the accumulator section of the regulator, the correct way is onwared to the safety valve and the suspension/brakes. The second way is through the piston in the centre of the regulator but this is unlikely and the third is back the way it came, via the non-return valve.
The good news is that you can repair this valve with the regulator in the car on the BX TD (I've done it twice). Make sure the car is securely supported and remove the accumumulator sphere and then take out the (10mm??) bolt you see together with the plate and the ball bearing that will follow it. Put the bearing back in the hole with a dab of grease to hold it in place and tap it smartly using a brass punch. re assemble and count the ticks.
You will probably want to clamp the feed hose to the pump to prevent too much LHM syphoning out. You must NOT use a steel punch as you will put a flat on the ball and it will not work. Its probably a good idea to start the engine after everything is reconnected before tightening the bleed/pressure relief bolt on the front of the regulator and let it run for a couple of minutes to expell air.
jeremy

freek · Unread post by **freek** » 04 Nov 2004, 02:43

Hello again,
I checked the return flows at the reservoir for the brakes and the suspension struts, by disconnecting the hoses. At idling speed there was no flow at all, so I think that the brake valve and the suspension struts are ok. When the car was at the highest position it surprised me that the interval increased to app. 30 seconds in stead of the 10 seconds at driving level.
I think that I will spend some time this weekend with examining the regulator as Jeremy suggested. I will let you know my progress!

jeremy · Unread post by **jeremy** » 04 Nov 2004, 03:28

When the car is fully raised the height correctors are open and so the suspension spheres are subjected to full presure from the regulator and act as accumulators! So you would expect the rate of ticking to slow but with in effect 5 accumulators rather than 1.
jeremy

freek · Unread post by **freek** » 24 Jan 2005, 00:44

Hello again,
It has been a while since the last posts. There was no urgence to fix the car imediately, and I was very busy. But with a coming trip to Austria next month, I have to start some maintenance. So today I seriously looked at the pressure regulator and looked after the non-return valve as Jeremy suggested. The ball bearing would not pop out (I was not so clever to use a magnet as was suggested at another post), but of what I could see the bearing was not rusted and can move freely in its housing so I do not understand why it would not close properly. Jeremy, may be you can explain why you have to tap it in place? And what you mean by not 'seated properly'? It should be moving freely though? So I decided to mount everything again and looked at the return pipes at the reservoir once more. And guess what: the return pipe of the brake control valve was giving LHM! So I will have to replace that one. Thank you very much Anders (and Jeremy of course) for giving me these usefull hints! Regards, Freek

alexx · Unread post by **alexx** » 24 Jan 2005, 01:56

Brake valves are known for internal leaking when older. Try also fully pushing brake pedal. In my case, ticking interval increased from 10-15 sec to 2 minutes (on my ex. BX) while I was pushing the pedal

jeremy · Unread post by **jeremy** » 24 Jan 2005, 04:50

The port of the non-return valve is simply a drilling in the casting. tapping the ball into its seat falttens the burrs and roughness and produces a smooher seat which seals nicely for a while (as in 100,000 miles or so) but eventually it isn't quite as smooth as it was. Re-seating the valve gives it a smoother seat and a better seal and - even better - doesn't cost anything.
Not a question of rust or restricted movement - just a bit of wear on a very small seat!
Don't like the idea - buy a recon regulator!
jeremy

freek · Unread post by **freek** » 24 Jan 2005, 17:27

Thank you Jeremy for your explanation. Sorry to ask, but what do you mean with your last remark 'Don't like the idea - buy a recon regulator!'?
Regards,
Freek