tic time not improved

dumbtime · Post by **dumbtime** » Mon Jul 23, 2007 3:59 pm

Hey All,

I changed my accumulator sphere the other day and the tic time has not improved. Ive been hassleing DavidR a bit too much and thought would spread the anoyance of a unknowledgable young man to the rest of you.

here is most of the story so far;
[DavidRutherford PM]if changing the Acc sphere hasn't improved the tic time, then there's something amis. I can only assume that the non-return valve is leaking rather badly... and that's a little bit more specialist to fix than you would have tools for to be honest. Not difficult or indeed expensive, but you must use an aluminium or brass punch to re-seat it.
Was the new sphere definitely new?
[/quote]
[My response]I assume it was new, I bought it from gsf in bristol. Though it didnt come in a box, it just had a plastic cap over the sphere srew head.

As for the non return valve, I dont know what that is, I had a look in the haynes manual but to no avail. As there are no big puddles on the floor I guess its some valve in the pressure regulator?

I dont think I'll be able to do this job as I am not the cleanest of workers as im concentrating too hard on what the hell im doing and clean is important, right? I am also unsure if my garage is willing, read on.

I remeber asking my garage to look at a few things, I also asked (AP autocare) about the tick time and if a new accumulator would fix it (I read that on here before I joined). They got back to me and said that the whole system would need to be over haulled & would be too big a job and expensive. Thinking back now it makes me wonder if they just didnt want to fiddle around with a really dirty old BX and just use the time working on much, much, newer & cleaner models for the same price. (my car's bottom has most probably never been clean since 1984).

Is this urgent? my car has had this tick time or a very poor tick time since Ive had it, 2 years ago.
Also after I did the front strut groan cure on one of the struts and I put the car back in normal hieght, the front randomly went up and down several times and then did it again after i switched off the engine.
[/quote]

So.... could my sphere be dodgy? what is the non return valve? Could someone help me to fix this if its not my sphere? and why was my car going up and down all on its own?

Andrew

Way2go · Post by **Way2go** » Mon Jul 23, 2007 5:27 pm

It sounds as if you do need to reseat the ball before you try anything else. This procedure won't cost you anything and judging from what I've read, the ball must only be hit once with a brass punch. titanic
Jeremy has posted this several times so if you search under his posts you will find the procedure in detail.

tom · Post by **tom** » Mon Jul 23, 2007 5:34 pm

Guesswork is not going to do any more than cost you money.
There is a proper procedure for determining why the tick time is short. Swapping the accumulator sphere is a good start. The tick time is low because the pressure in the accumulator leaks away too quickly due most probably to fair wear and tear. There are a number of pipes that go back to the reservoir. Most of these are return pipes for the various components in the hydraulic system. One of these will have two pipes joining together near the reservoir, one a hard plastic pipe connecting into the rubber one. Prise this pair off at the reservoir and plug a 10ml syringe body(without the plunger fitted) into the open end so that you can now measure the amount returned per minute. This pair of pipes is from the doseur valve, which is the main brake valve. It wears. A lot. The upper limit is 3.5cc per minute so you hold the syringe (or measuring tool as it now is) upright, start the engine and time how long it takes to exceed 3.5cc. It won't be a minute. It will be a lot less, I'm sure. There are other things that can be done. Jeremy swears by reseating the ball in the Pressure regulator which can help, but measuring the speed at which the doseur is squirting away the accumulator pressure is the natural first step for an aged BX. Just how long is the tick time by the way. Allowing for some excess wear in the doseur (Which has little effect on the braking efficiency so don't worry) an otherwise sound system should tick at 30-40 second intervals with the car level and empty.

jeremy · Post by **jeremy** » Mon Jul 23, 2007 5:44 pm

There are 3 ways LHM leaves the accumulator:

Onwards - as it should to the rest of the system

Down the piston/valve in the centre of its mount - some will always go this way but it shouldn't be excessive.

Back the way it came - via the non-return valve.

The Non-return valve is a simple ball bearing retained by a small metal plate which is visible when the accumulator sphere is removed. It's loose in the hole and should seal against the hole (or inlet port I suppose to be precise) at the base of the hole it sits in. Ball bearings sitting on holes are in fact common valves in Citroen and other automotive applications and work very well - but need to be seated - which can be done by tapping them smartly onto their seat - ie the hole.

Nice and simple to do - just a couple of problems:

If you strike the ball using a steel punch you will probably put a flat on it - so use a brass (aluminum - etc) punch. I did the first one using an old copper MIG welder nozzle as it was sitting in my toolbox - and I held it onto the end of a steel punch with an old Citroen pipe seal which was also there.

It must be struck smartly once. This isn't a heavy blow - this is unnecessary and may damage it - nor is it multiple blows which will simply produce a number of overlapping seats which won't seal either.

The most usual thing to collect the ball bearing in when you have removed the cover plate is your eye socket - together with a few drips of LHM. OK this is frivolous but the thing will drop out - so be prepared and place a tray under it to collect it.

You can hold the ball in its socket with a dab of grease. If you don't clamp the hose from the reservoir to the pump LHM will syphon through the pump and drip gently and may cause the ball to fall out.

I've done the job on my TD with the regulator in position - just with the sphere removed.

Usual health warning - make sure the car is properly supported as if it drops it'll probably kill you.

If you would like to learn how it all works have a look at Gabor's excellent text book:

http://www.tramontana.co.hu/citroen/

and follow the links to 'Technical Guide - (Top left corner)

dumbtime · Post by **dumbtime** » Mon Jul 23, 2007 10:36 pm

The tick time is 1.5 to 2 seconds just above idle speed, when it is idle its just a continuos hiss!

Its always been like this since Ive had it (2yrs now) DavidR said "I do wonder if the non-return valve has ever seated properly."

This made me think and I remeber my grandpa getting a new hydraulic pump just looked in the big fat BX file and found it was replaced in 2000 at 100 000 miles. Is that a normal life span or has the pump been working hard all its life?

Im working all this summer so only really got weekends and im away this weekend seeing my girlfriend in London. So I think I'll only have time to maybe measure the brake return fluid. Hopfully my other grandad will have a 10ml syringe as he worked for Squibb (a surgical supplies company) and got loads of random stuff. I fixed the return or vent pipe on one of the struts at the weekend with a bit of tubing from a caphiter bag!

I'll get this done and let you know if it shoots out, if it does fill up too fast i guess I quickly pull the syringe out and shove the pipe back in place?

As for the re-seating of the bb, I believe I understand what needs doing, though what is a steel punch? is it a bit of steel rod that you then place on the bb and give it a good tap with a hammer? but obviously use brass or aluminum.

I probably wont get time to do this untill 2 weeks time, but I guess this syringe jobby will let me know if this needs to be done.

Thanks alot and thanks for the link to that book, I'll have a little read of that tonight.

Hopfully I'll get back to you by the end of the week about the break valve. If it is leaky I guess I need to follow that sticky post about the doseur valve? which I happened to read the other day.

mountainmanUK · Post by **mountainmanUK** » Mon Jul 23, 2007 10:43 pm

Are you sure that the bleed screw on the pressure regulator is screwed in properly?
A tick time THAT fast I have only ever come across when unscrewing the bleed screw 1/2 a turn for bleeding after doing work on the hydraulics, but then not screwing the bleed screw back in again properly.

Probably WAY off mark, but worth considering, as it doesn't take long to check, and costs nothing!

WARNING! As usual, when doing any jobs on a Citroen hydraulics, make sure that the car is properly supported, as it can drop VERY quickly, and WILL kill you!!!!

dumbtime · Post by **dumbtime** » Mon Jul 23, 2007 11:04 pm

Yep, im pretty sure it's closed, I remeber that being that last thing I did before bring the car into land! though I will check when I do the syringe thingy as my mind could be playing tricks on me.

jeremy · Post by **jeremy** » Mon Jul 23, 2007 11:26 pm

If the tick is that rapid I wonder if the ball bearing under the bleed screw is still there or if the screw has been removed at some stage in error and the ball lost? and the screw replaced without it.

Its not the same size as the non-return valve.

Way2go · Post by **Way2go** » Tue Jul 24, 2007 3:48 am

That hiss without achieving a click at tickover "rings a bell". I had this prior to changing the front strut which catastophically failed totally with an LHM fountain. I think it started with a small leak into the return circuit which gradually and significantly increased prior to total failure.
Two things lead me to this conclusion 1) the tick was achieved at tickover without hiss. 2) the mpg improved significantly presumably from a lower duty cycle of the HP pump?
So, advice is to check the passage of fluid in the strut returns with the car on normal suspension. (I believe this should be next to nothing when the car is up & stable)

jeremy · Post by **jeremy** » Tue Jul 24, 2007 7:12 am

You can eliminate the suspension by dropping the car - which shuts the height correctors and opens the returns.

Full height leaves the height correctors open and all pressure is available for the suspension - with the suspension spheres functioning as accumulators. If the ticking frequency now drops then suspect the accumulator sphere.

Way2go · Post by **Way2go** » Tue Jul 24, 2007 1:38 pm

jeremy wrote:You can eliminate the suspension by dropping the car - which shuts the height correctors and opens the returns.

mmm

I see what you mean but surely this doesn't identify which strut (if so) could be causing a problem, because the strut returns never open, they only deal with leakage and that leakage in my case became substantial.

Presumably strut lowering is normally only able to occur through back flow in it's hp feed pipe.

dumbtime · Post by **dumbtime** » Tue Jul 24, 2007 2:20 pm

hmmm, all interesting and starting to get out of my depth, though i think I understand.

[quote jeremy wrote:]I wonder if the ball bearing under the bleed screw is still there or if the screw has been removed at some stage in error and the ball lost?[/quote]
Whats the size of this ball and where can I get one? so when I come round to checking it and its not there I'll have one to hand to replace. and I assume it gets re-placed the same way you thought it escaped (but in reverse).

[quote jeremy also wrote:]You can eliminate the suspension by dropping the car [/quote] this i think I can do, I just count the tick time when the car is droped and then count the tick time when fully raised, correct? The hiss does have the occasional break for a second or two but is random.

[quote way2go said]So, advice is to check the passage of fluid in the strut returns with the car on normal suspension. (I believe this should be next to nothing when the car is up & stable)[/quote] how do you check this, is it a similar procedure thats done for the brake valve but with a different pipe?

I'll try and do these checks tonight, accept for checking if the ball is in the valve, I'll do that the weekend after next.

dumbtime · Post by **dumbtime** » Tue Jul 24, 2007 2:24 pm

why cant I get quotes to work? Ive done it once before but it said qoute: then quoted, I want it to say "jeremy worte:" then qoute

jeremy · Post by **jeremy** » Tue Jul 24, 2007 2:51 pm

The ticking might be due to leakage through the suspension. The simple way to eliminate the suspension from suspicion is to shut it off by dropping the car. If the tick rate magically decreases - look at the suspension (not the brakes, accumulator or anything else)

If the suspension is the problem you will probably have some (possibly minor but probably major) leaks in the vicinity. The return circuits are excellent but can't really cope with a severely failed component.

Another possible cause could be air leaks in the pipe from the reservoir to the pump. Both ends must be sound and tight. Air in the system will cause all manner of strange problems as its compressible in a system that is designed to operate with an incompressible fluid, and it'll pass through many valves that LHM won't.

dumbtime · Post by **dumbtime** » Tue Jul 24, 2007 9:49 pm

Now then,
when the car was in its lowest position the tick time did not change and was still hissing. So I take it the struts are ok.

I measured the time it took for the break return fluid to reach 3.5cc and.......
...16 seconds, Whahey!!

!!

so I take it the doseur valve needs repairing? can some one confirm this? and is it still wise to seat the ball in the non return valve?

Wow, Ive learned alot from this post.
Thankyou to you all.