2.5td Brief Hydraulic History

Hi all,

I was pretty thorough in cleaning the hydractive blocks, I stripped them as far as I could, everything out except the pressed in ball bearing and the parts behind the rolled pin (I couldn't get them out!). All the parts were put into an ultrasonic cleaner for several cycles in white spirit, it was surprising how much gunk came out, I changed the white spirit several times. I did check the 'button' valves and they were clear, I also noticed they were marked with 2 and a 6, maybe 2.6 mm aperture?

I thought about the pipe size but the pipes from the hydractive block to the cylinders is much bigger than on non hydractive cars. So my theory is that the fluid in the sphere merely get shuttled from sphere back to the block and vice versa. If this only moves such a short distance then will the flow through the hydractive block be any better? The height corrector obviously has more fluid flow.

Keep the comments coming please.

Steve.

Wow that's high-tech stuff, I'm impressed, and it worked well from what you say!

Crossflow: my opinion is don't be cheated by the "smallness" of all characteristics; when the right wheel hits a bump, the few ml that the cylinder pushes will be absorbed by all 3 spheres on the axle -pressures are always equally distributed everywhere, from side to side-. If one sphere "feels" e.g. 87bar, then the other 2 also will necessarily "feel" the same, at the same time -LHM is incompressible so there shouldn't be any delay or absorption-. Remember e.g. the difference between a fully pressurised accumulator sphere (170 bar) and a "cut-in" pressurised one (145 bar) is about 17ml -tiny-! This suspension really operates with amounts of LHM that look insignificant.

Afaik the centre orifice for the "button" dampers on hdyractive block of the XM is 1.25mm.

cheers
George

I like the comparison. So where is the easiest and lowest part of the system to break into & drain?

It would have to be a pipe union somewhere that is easily accessible and not prone to damage by undoing it.

Any ideas?

Here's a photo of my bleeding system for the front struts.

http://www.flickr.com/photos/7328220@N02/2340013465/

It is surprising to see just how little flow you get from the end of the pipe but then again with a 6+2 pump it is a very small displacement, maybe that's another reason why flushing takes so long?

Following your comments George I think I'll take a different approach to the speed bumps our council loves so much. Normally I straddle them but in future I'll go for 1 wheel off and 1 wheel on. Thanks for the tip!

As for the button dampers I don't know then regarding the numbers, I did check with the shank of a small drill bit which was one of the smallest I had.

Those ultrasonic cleaners are great and don't cost much from Ebay either.

Steve.

This post has been edited by steelcityuk on March 17, 2008 04:05 pm

Great, that's what I was thinking also, but your execution is waaay neater!
G

NOOOOOOOOOOOOOOOO!!!! I cannot shout louder...

Don't do this with a not-soft suspension! Aren't you pitty of your strut tops?

Trust me, the slaloming worked and is not harmful to the car. Trust me, all you need is to put some discipline to your self. The moment I put hydraflush in I said "right, this is it, the ball is rolling, let's take max advantage of it"! It is ridiculous some times -shoppers at the supermarket car park look with curiosity-, other times your partner is dangerously bored (-"Come on, let's go!" -"No, I still have to do 9 more of those"), other times the neighbours may think "who is that stupid that is wasting his petrol seating and doing this silly up-downs, why doesn't he just go home, at 11pm?" But I don't care; I have an objective. As for the slaloms, I took the risk of doing them on empty motorways late at night but I'm sure you will know some car-park style area that's empty -again, no need for speed, just doing "8s" at 20mph will do the job.

cheers
G

This post has been edited by jorgy9 on March 17, 2008 06:55 pm

Steve, BTW, since you've dealt with the e-valves, have you checked if they are leaking at all? For the front one, just start engine, height normal, under car, pull the return pipe off the e-valve's body and look (shouldn't miss a drop). No reason looking further if the e-valve(s) leak therefore cannot send all the pressure towards opening the hydractive piston-valve. I had my front leaking very visibly and put a new one from Cit. And still this is a static test, could be well leaking when receiving back-pressure shocks from bumps -but that's impossible to test unless you brought the retun pipe in the cabin and looked while driving-.

cheers
George

My brother says an Indie in London advised the following to "shake up" the muck in the hydraulics of his Xanthia.

In a suitable space (eg empty car park) get up some speed in reverse then hard on the brakes emergency stop.

Does make some sense, not something one usually does so it might dislodge some of the contaminants.

I tried it once but don't really need any more whiplash!

I tuned my radio to 153 LW on the way to work today and it would appear the electrovalves are working. Boring station though!

Message recieved and understood!

I've already started the 'wiggling' when the road is empty, just hope I don't get seen and breathalised (spelling?).

I've not had chance to check for leak back yet but should over Easter when I add more hydroflush.

I've still got the LED rigged up so I can see what it's doing. Interestingly when I had the electrovalve in bits I metered the coil and it's the same resistance both ways so I guess the diode is fried, good job I added some extras in the ecu housing.

Steve.

Hmmm "breathalised" ? It's probably "breathalysed" I guess? Another new word to me! And another faulty neologism that some clever -but not well informed- person thought of...

This reminds me of the sadly now established in English confusion between the -athlon and -athon suffixes. Sad? Why?? Because language looses its inherent synthetic characteristic, that allows it to produce new meanings from old and, the other way round, explain various words by breaking them down into their components. This ability is one major benefit of "synthetic" languages -like Greek in this case- which, along with Latin, lend this power to English -an otherwise "isolating" language-. So:

Greek "-athlon" is a suffix from "athlos" whcih means "sport", "game". So, "Triathlon"> "a sport consisting of 3 games".

Greek "-athon" is not...Greek. In modern English, it's wrongly mistaken with the above "-athlon", because of a confusion with "Marathon". Marathon doens't denote any sport at all, and cannot be broken down further; it's just the name of an area out of Athens, simply given from the "Marathos" flower (Foeniculum Sativum). Here they are in white/yellow in a photo of Marathon today:



When, in 490BC, Greeks beat Persians in the plain of Marathon, legend has it that a greek soldier, Pheidippides, ran all the way to Athens to bring the news of victory, then collapsed to death on the spot. This event inspired the modern 42km run -distance from Marathon to Athens city center- that we call a "Marathon".

Marathon battle - the tactics:



Marathon, tomb of the 192 Athenians fallen in battle:




Unfortunately you see all kinds of -"athon" things like:

"Snor-athon" (!)
"Science-athon"
"Reward-athon"
"Web-program-athon"
"Urb-athon"
..and anything else imaginable when "a game of endurance" is what meant to be denoted. Wrong...."-athon" doesn't mean anything...

Ok, so what's the relation of all this with Steve's "breathaliser"???

Well, this would be composed from "breath" (obviously) and the suffix "-aliser". What's..."-aliser"? Well...nothing!!! Just another faulty neologism obviously inspired from "analysis" > Greek for, well...analysis!

"ana-" + "lysis" > to break down something into its components, to "diss-solve".

Problem is, as with..."Snoreathon", the way "breathaliser" has been constructed makes for totally missing the meaning of "analysis" or "lysis"; as a result, one is more prone to confuse it with the totally irrelevant "-iser" suffix (from Late Latin -izare> from Greek -izo) that just denotes an "action", as in

"revitaliser"
"womaniser"
"organiser"
etc.

Bottomline, if "breathalyser" had been rightly rendered as "breathanalyser" I suspect very very few people would have a dilema between "breathaliser" and breathalyser", that's just because they wouldn't have any doubt it is made out of "breath" and "analyser"!!

Result? More and more £,£££,£££,£££s are spent in the UK in trying to teach people how to write correctly, while the inherent logic in language that automatically minimises this, that took 1,000s of year of development to get to us, is being destroyed day-by-day by "breathalysers" and "Snorathons"...BTW, is there not in the UK such a thing as an "academy of English language" like I know they have in France, Spain, etc not to allow such stuff to go out and spread?

Hmm, sorry folks, but I really needed a break from oils and suspensions and hydractives... Hope Noz doens't mind too much...Demag, sorry to highjack your thread with battles and grammar....

cheers
George

hmm hydractive: "hydro-"> from Greek "hydor" = water + "active"...ooops, I'll shut up NOW!

This post has been edited by jorgy9 on March 18, 2008 12:36 pm

Great idea Tim, was already thinking of doing slaloms in reverse to work more the rear suspension that lags behind the front in improving, but had not thought of the hard braking element, much more effective indeed!

cheers
George

Ah...Er...

I'll check the dictionary next time. ;-)

Steve.

Please, boys boys! Settle down at the back! What's all this chatter?

Come on pay attention or you will end up doing lines!

I must listen in class
I must listen in class
I must listen.....................................