Hydraflush - what to bleed or remove

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charentejohn
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Hydraflush - what to bleed or remove

Post by charentejohn »

Just about to do this having recieved my 5L bottles of flusg and new LHM for later.
I have read the how to do the change sticky and am ok with emptying the reservoir and brake bleeding, but have a question on what else to remove fluid from.

Spheres and brakes are a 'dead end' ?
My question is, if I change the fluid in the reservoir for Hydraflush and then start the car to do the rest what happens ?
Some old LHM in the pump and pipes will be mixed with the hydraflush but not much.
The brake pipes will contain old LHM until I bleed them filling them with hydraflush.
What about the LHM in the Spheres though ? Hope there is no need to drain these.

Just trying to understand what happens as regards getting rid of the old LHM.
I assume verly little left when hydraflush fitted so very diluted.
Once it has done it's work and the new LHM is fitted the old LHM will be even more diluted, but how much hydraflush will always remain in the mew LHM. Not much I assume and no problem at that dilution ?

Just checking before I get the spanners out, also I may need to drive the car between fitting hydraflush in the reservoir, any problems if I do.
I guess no real problem as the rest is still trapped in 'dead ends' ?

Thanks John
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Re: Hydraflush - what to bleed or remove

Post by Hell Razor5543 »

The only "dead ends" (as far as I am aware) are the brakes. The rest circulates, especially if you do a series of Citrobics. Bleeding the brakes will get any air bubbles out (which can occur when you change the LHM fluid), and then get the hydraflush down to the brakes. I will always bleed the brakes if I do anything to the hydraulics, to make sure I haven't got bubbles in the lines.

I couldn't say how much hydraflush would remain after you drain it out, but if you bottom out the car, loosen the pressure bolt on the regulator, and turn the steering from lock to lock a couple of times most of the fluid should get back to the reservoir.

Hydraflush needs to remain in the system for a while to do its' job. IIRC 5,000KM, (My Xantia, Gracie, is currently on a hydraflush cycle), and I will replace the hydraflush with LHM when she hits 130,000 miles (she will have covered about 3,000 miles by then on the cycle).

Hope this helps.
James
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charentejohn
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Re: Hydraflush - what to bleed or remove

Post by charentejohn »

Thanks, that all makes sense.
I know a small amount of old fluid will always remain unless it is all dismantled and drained but sounds like the process you describe will move most back to the reservoir.
I will make sure I don't need the car for a couple of days and do the brakes at the same time.

Whatever little remains will be almost nothing by the time the new LHM goes in.
So id 10% remains and mixes with the hydraflush, when the new LHM is added later the old fluid will be 10% of that.
So at the end only 1% of the old fluid remains, and 9% hydraflush, obviously normal to have that after this process
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Re: Hydraflush - what to bleed or remove

Post by 6speedmanual »

I took soem lengths of leak return pipes from a scrapper last weekend.
On the transparent sections, there is a visible film of black sediment laying along what was the bottom of the tubes.
Presumably this is what Hydraurinceage helps to shift back into suspension so it can be removed wne the fluid is changed back to LHM.
charentejohn
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Re: Hydraflush - what to bleed or remove

Post by charentejohn »

I do believe that is what I am trying to get rid of, see this link http://www.forum-auto.com/marques/citroen/sujet2406.htm" onclick="window.open(this.href);return false; taken from this sites 'sticky' pages.
The photo of the filters at the end shows them covered in black stuff, scary.
So cleaned up then hydraflushed should see them covered again as they have only trapped the loose stuff so far, the flush should loosen the rest.
You must be the change you want to see in the world - Mahatma Gandhi
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Re: Hydraflush - what to bleed or remove

Post by 6speedmanual »

Nice link CJohn.
When I changed the LHM on my SX, I extracted the oil using a Sealey vacuum oil change pump.
Took out the tank and cleaned it and all the mesh filters. This was on a car with 163K miles. The LHM was a dark brown colour - yukk! Now runs bright green - nice!

On an old car, the wear rates almost certainly increase as tolerances open up and seals get weaker. Changing hydraulic oil more regularly cannot be a bad thing, so I intend to do it every 25k miles. (I drive about 35k per year by the way)
I obtained, from a scrap yard, spare mesh filters so the actual swap over is quicker. I can then clean the other ones to keep ready for the next service.

Incidentaly, with the convenience of a vacuum pump, it is also easy to suck out and refill PAS systems on "normal" cars.

The extracted power steering or LHM fluid can be conveniently disposed of into the fuel tank of my Peugeot 306 idi diesel!

Peter
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