brake bleeding

mattpc · Post by **mattpc** » 14 Aug 2005, 17:43

The new Xantia needs its brakes bleeding in my opinion. The LHM has recently been changed, as has the accumulator but it's pulseing like a good un under braking. I've looked at the method in the Haynes and it seems ok but they do not mention whether the hydraulics need to be depressurised or not first. I presume that they DO NOT. Is this correct?

Rostami · Post by **Rostami** » 14 Aug 2005, 17:59

You are correct.
Just run the engine, put the car on solid stands and bleed. You need assistance for pushing the break pedal...

harryb.48 · Post by **harryb.48** » 14 Aug 2005, 18:13

Just one other thing to remember- the rear suspension must be at the high position to keep the brake lines pressurised when bleeding the rears.
Also ,to avoid snapping of the bleed nipples,a ring spanner is a must as is pre-lubrication ,especially around the rear nipples and careful slackening of same.
If really stuck,some heat and shock around them will help.
If you want or must do the job single-handedly,then a piece of wood jammed between seat and brake pedal does the job nicely.

Post by **smashymike** » 14 Aug 2005, 18:41

I've wondered about this, do you bleed the brakes by constantly topping up LHM container? What happens to 'used' fluid? Are the bleed nipples likely to be mashed? I don't think my fluid has ever been changed, if it has then i very much doubt if the brake ends have been bled of air. Could this accountfor the 'on,off' stopping i'm experiencing. I just put it down to 'the abs'.

oilyspanner · Post by **oilyspanner** » 14 Aug 2005, 18:52

I went to the aquarium shop and bought a long piece of plastic pipe, it reaches from the rear bleed nipples all the way to the reservoir, i sat in the seat, brake pedal pressed and raised the rear of the car, it was quite a long time before the offending bubbles came past me, clearly visible through the clear pipe.
Stewart

paranoid · Post by **paranoid** » 14 Aug 2005, 19:37

When this problem occured on mine, I had to bleed at least 1-2 litres from either side before the bubbles appeard.

fastandfurryous · Post by **fastandfurryous** » 14 Aug 2005, 19:49

I've done the same as mr Oilyspanner above, using a long length of washer hose. It's far less wasteful of LHM to return it to the tank, and it also means that you can circulate LHM through the brake system for as long as you like to be utterly sure that all the air/nitrogen is out of the system.

mattpc · Post by **mattpc** » 14 Aug 2005, 20:51

hmm well I had a go. I got two different thicknesses of tubing of course one was far too wide and the other too narrow. I had to use the wide one in the end and most of the LHM ended up on the road.. Anyone know the opimal size in mm for the tubing? Also how long did you spend bleeding each side and how much fluid did you draw? I found it difficult to get much fluid out without actually almost removing the bleed nipple nut thing! Then of course when I slackened it right off LHM escaped from various different places. I've put it all back together since then and the car does brake a bit more smoothly but it's still not right. Perhaps I should have persevered or gone to another shop to find some better fitting tubing..

fastandfurryous · Post by **fastandfurryous** » 15 Aug 2005, 01:14

The car does have to be in "high" to get full pressure at the rear brakes for bleeding, and you have to stand on the brake pedal fairly hard.
The length of washer hose I used just needed softening a little in some hot water, and then went on perfectly.

mattpc · Post by **mattpc** » 15 Aug 2005, 04:30

Thanks for the tip. The braking does feel better now despite my pretty pitiful effort. I'm probably going to wait a bit before doing it again as I'm having new spheres all round soon so It should be again done once those are on I think.