Bleeding the brakes

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Road_Hog
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Bleeding the brakes

Post by Road_Hog »

Need to bleed the brakes tomorrow (actually today - Sunday) and have two questions.

Does anyone know what size pipe (clear plastic stuff) is best to connect to the nipple to bleed it into a bottle?

Secondly, I bought a bottle of Dot 4 brake fluid today and upon reading the details, it said not suitable for systems that use mineral oil and then had Citroen in brackets. The car is a C3 BTW.

Now, I'm not that knowledgeable on brake fluid, but with engine oil, I know you can't mix mineral with synthetic, but I always though you could use either or, as long as you didn't mix them. Is brake fluid not the same, or does the Citroen need some specific mineral oil?
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Re: Bleeding the brakes

Post by Xaccers »

What it means is proper Citroens with green blood (hydraulic systems running on LHM+ which is a mineral oil) not your weird steel sprung master cylinder brake contraption ;)
No idea what DOT number the C3 uses so can't say if DOT4 is right or not.


Addendum: a quick google suggest DOT4 is the right stuff.
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Re: Bleeding the brakes

Post by Road_Hog »

Xac wrote:What it means is proper Citroëns with green blood (hydraulic systems running on LHM+ which is a mineral oil) not your weird steel sprung master cylinder brake contraption ;)
No idea what DOT number the C3 uses so can't say if DOT4 is right or not.


Addendum: a quick google suggest DOT4 is the right stuff.
Okay. But I'm still not sure. Is the glycol based stuff I've got, okay or does it need to be the LHM mineral stuff?

"Because oils damage rubber seals and hoses in the braking system, brake fluids are not petroleum-based. Most brake fluids used today are glycol-ether based (what I have bought), but mineral oil (what the back of the bottle that I have bought is telling me what I need for Citroens) (Citroën liquide hydraulique minéral LHM)"

http://en.wikipedia.org/wiki/Brake_fluid" onclick="window.open(this.href);return false;
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Re: Bleeding the brakes

Post by Xaccers »

What you have got is correct for the C3.
LHM is for older Citroens with a combined hydraulic brake, steering and suspension system, such as the Xantia, BX, Xm, which gives them superior ride quality and braking.
Do not put LHM in your C3.
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Re: Bleeding the brakes

Post by myglaren »

Xac has it right. Any Citroen with a C in it's name will use DOT4.
As for the pipe, can't say as it was so long since I used any but your local DIY place should have some, or a aquarian supplier and your local motor spares place will have suitable stuff in (usually) but consider getting a one man kit. The one I had consisted solely of a length of rubber hose, blocked at one end and with a non return valve in it to prevent air being drawn back into the caliper, followed by a small slit to allow the fluid & air out.
Image

They are a bit on the short side and you will need to stand the receptacle on a brick for it to reach. The end does not need to be submerged in fluid as it would with just a tube with no none return valve. That also needs two people to do it.

Deadly simple to use. Clean and crack the bleed nipple, fit the tube, put the other end in a receptacle (jam jar or similar) pump the brakes, usually five times was sufficient, tighten the nipple, remove the tube, check the reservoir level and top up, move on to the next wheel.

Have a look here, scroll down to the 'Brake Bleed Tube' - £0.96.
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Re: Bleeding the brakes

Post by citronut »

DOT4 is what you require and does replace and mix with earlier ( DOT ) vegtable oil brake fluids,

conventional brake systems are veg oil ( what ever the DOT No. ) which will eat you paint also is water solubale (so you car rinse away any spilage with water), and proper hydraulic citroens are mineral oil this wint hurt your paint and you must not mix with veg oil brake fluids,

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Re: Bleeding the brakes

Post by HDI »

That is not correct. Brake fluid has never been vegetable oil based !
They are Glycol-Ether based fluids. The confusion is with seal compatiblity. Mineral oil fluids will attack seals intended for Glycol-Ether based fluids as these seals are natural rubber based rather than Nitrile or Neoprene for mineral oils. Hence the issue with Citroens, models with central hydraulic systems will have nitrile or neoprene seals to resist LHM, which is a mineral oil based fluid. Other Citroens use normal Glycol-Ether based brake fluid for which the seals are natural rubber.
Generally brake fluid does not now attack modern paint, that was a problem when Automotive paint was Cellulose. Glycol-Ether based fluid can be washed away with water, this is why these fluids need regualr changing as they absorb water, which will corrode brake systems from the inside.
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Re: Bleeding the brakes

Post by citronut »

conventional brake fuid has always been known as vegatable oil based in all the years i have bee in the garage trade, and will destroy hydraulic citroen seals, thats why you must not put brake fluid into an LHM system,

antifreeze is Glycol-Ether based

regards malcolm
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Re: Bleeding the brakes

Post by Xaccers »

Very early brake fluid was castor oil and alcohol.
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Re: Bleeding the brakes

Post by HDI »

If brake fluid was ever composed of veg or castor oil it was in the VERY distant past. I assure you it isn't now or hasn't been in at least 50 or more years. Anti-freeze is Ethylene-Glycol.
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Post by addo »

LHV, the precursor to LHS (NOT LDS :shock: ) may be what Malc remembers from his 'prenticeship.

You can also knock up an LHS workaround with DOT3 and 5% castor. Some add a bactericide.
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