Accumulator tick time

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MikeT
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Accumulator tick time

Post by MikeT » Fri Nov 16, 2007 4:44 pm

Is there a particular height setting needed to assess the duration between the ticks or doesn't it make any difference?
98 Xant 1.9TD fuelled on veg
93 Granny SORN
90 VFR750 Breaking

CitroXim
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Post by CitroXim » Sat Nov 17, 2007 2:40 pm

Mike, It's official, your're Crazed :lol: :lol: :lol:

I gave this tick time some thought and experimentation today. On my TD (I swapped the brake flexi this morning with a nice shiny new one 8) ) it makes little odds whether low, normal or high but that may not be a fair test as my TD hydraulics are a little worn and the tick (actually hiss) rate is only about 20s.

In the back of my mind I believe that on the FCF there was a useful thread saying it can be very useful for diagnostics to compare tick rates at differing heights.

The following may not be correct as I'm working from scratch here...

In low, the tick rate will be longest as there is the least demand on the hydraulics, all struts being right down and fluid demand for the rear brakes being at a minimum.

If the tick rate goes up in normal that would suggest there is excessive leakage in the struts. If the tick rate goes up even higher on high then it would suggest the brake doseur has excessive leakage as in high, the rear suspension will allow more fluid through to the doseur.

There are factors. The statements above will generally apply to cars like yours with the 6+2 pump and anti-sink. The early MK 1s, like my TD, have BX hydraulics and a very hungry power steering system sharing a common pump and things like flow distribution valves that can mask other areas suffering excessive leakage.

Hyrdactive cars will be different again.

Generally, I reckon that if your tick rate is substantially the same at all heights, you are healthy :) If you're not, then the only sure-fire way to track it down is to examine how much is flowing along the leakage return pipes. Generally, no more than a dribble and you're OK.
Jim

'98 Xantia 1.9TD in Red - Gabriel the Bus...
'96 Xantia Activa in Red - My favourite toy...
'07 Pug 207 in Blue - The Deathtrap...
'15 Giant Defy Bike in Blue - Daily rider...
'16 Giant TCR Bike in Black/Lime Green - Fine weather only...

CitroXim
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Post by CitroXim » Sat Nov 17, 2007 4:29 pm

I've just tried the tests on my Activa.

Two problems though, the tick time is measured in eons and compared to my Mk1 TD, it takes so long to rise and fall :? The TD almost flies up and down but my Activa takes ages...

To have really done the tst properly, I'd have needed to have pitched a tent and laid on catering.

In the time available, the tick rate seemed pretty consistent at all height settings.
Jim

'98 Xantia 1.9TD in Red - Gabriel the Bus...
'96 Xantia Activa in Red - My favourite toy...
'07 Pug 207 in Blue - The Deathtrap...
'15 Giant Defy Bike in Blue - Daily rider...
'16 Giant TCR Bike in Black/Lime Green - Fine weather only...

MikeT
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Post by MikeT » Sat Nov 17, 2007 5:54 pm

Why crazed? But I thought you knew that already! :lol:

Do you recall what the rate was when we checked it after replacing the accumulator? Before, it had fallen to about 7 secs which was the reason it was replaced. After replacement I think it went up to about what, 45/60 secs?

Well the reason I'm asking about tick rate is because either;
1. I'm testing it wrong.
2. I've gone deaf.
3. Cleaning the LHM filters has improved the tick rate to well over 3 minutes!

If you haven't chucked out my old accu, keep it, it may be perfectly serviceable!
98 Xant 1.9TD fuelled on veg
93 Granny SORN
90 VFR750 Breaking

jeremy
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Post by jeremy » Sat Nov 17, 2007 7:21 pm

The regulator cycling is the interval between accumulator charges - which means if no LHM leaves the accumulator - there is no need to recharge it and the thing won't tick.

Various components leak a little and that leakage is replaced. On a late Xantia with the 6 x 2 pump the accumulator only handles the suspension and brakes. With the car at anything but full height the height correctors will shut when the car is at the correct (or no) height.

With the car fully raised the height corrector remains open and the thing basically tries to break the chassis by continuing to pump. In this position the suspension spheres are subjected to the full output and may function as accumulators and slow the ticking - when they have reached the accumulator pressure (which may take some time and is probably not advisable.)

Tick time should not be measured at maximum height as different results will be produced.

MikeT
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Post by MikeT » Mon Nov 19, 2007 1:19 pm

I'm pleased to report that I timed the tick interval today at normal height and the elapsed time is indeed a nice long 3.29 secs, the same as it was when set to highest after cleaning the LHM filters.

Therefore Jim, if your TD is giving 20secs, you might want to fit my old accu if you still have it? Remember we suspected it may not have failed as it didn't squirt LHM when released and that the tick time barely improved after fitting the new accu?

For anyone with low tick rates that are considering changing their accumulator, I would highly recommend cleaning their LHM filters first.
98 Xant 1.9TD fuelled on veg
93 Granny SORN
90 VFR750 Breaking

CitroXim
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Post by CitroXim » Mon Nov 19, 2007 3:24 pm

Mike, I hope you mean 3.29 MINUTES and not seconds :lol: :lol:
MikeT wrote: For anyone with low tick rates that are considering changing their accumulator, I would highly recommend cleaning their LHM filters first.
Good tip :wink: Often missed...
MikeT wrote:Therefore Jim, if your TD is giving 20secs, you might want to fit my old accu if you still have it? Remember we suspected it may not have failed as it didn't squirt LHM when released and that the tick time barely improved after fitting the new accu?
No, It's not the accumulator Mike, it's the pressure regulator ball needing reseating. It does not tick, it hisses! Everyone knows when I'm around in the TD as they can hear it hissing.. Robyn really made a point of it the other evening!!!

It has hissed all the time I've ever owned the car, never better or worse so I've yet to get round to sorting it. The pressure regularor is a bit weepy so when I do the clutch, I just may replace it.
Jim

'98 Xantia 1.9TD in Red - Gabriel the Bus...
'96 Xantia Activa in Red - My favourite toy...
'07 Pug 207 in Blue - The Deathtrap...
'15 Giant Defy Bike in Blue - Daily rider...
'16 Giant TCR Bike in Black/Lime Green - Fine weather only...