Xantia rear brakes not working?

mrjohnson · Post by **mrjohnson** » 24 Oct 2006, 10:31

First a bit of background.

Checking over my '93 1.9 TD hatch before its MOT, I decided to change the rear pads. When I took them out they were wedge shaped. Took off the calipers to clean the rear faces (they corrode and push the caliper out of square). In doing this on the n/s, the brake pipe fractured at, and started leaking from, a rusty spot. A bugger, but better on the drive than on the motorway!!

I put a new pipe on the next day; about half a litre of LHM had leaked out. Before I topped it up, the STOP light only came on at the highest suspension setting.

Now the problem.

I tried to bleed the back brakes but got NO pressure when depressing the brake pedal - the LHM did not flow out. It did, however, creep up the bleed tube VERY slowly, and bubbles came out then stopped. Put the wheel back on, and it spun freely with the brake pedal down hard. Same story at the other side.

The car stops OK when driven (presumably on the front brakes).

So...some questions for the experts.

1. Since the rear brake pressure is based on the rear suspension pressure, when one rear wheel is jacked up would you expect ANY braking anyway on that side???

2. Could air have got up into the brake control valve (in the back of the engine bay). Is it possible to bleed this valve?

3. Do these brake control valves tend to fail? I guess it's possible it was already broken before I started this saga.

Any advice welcome.

Regards,

Martyn

jeremy · Post by **jeremy** » 24 Oct 2006, 11:32

The rear brakes are powered from the rear suspension - ie the pressure in the rear circuit is tapped for the brakes - and if you look you will see that pipes run from the rear suspension to the doeseur and back.

So - no load - no pressure! If you put the thing on full height the height corrector is open - and loads of pressure.

Bleeding: Citroebics (raising and lowering the car) will clear air from most of the circuit, leaving the one way limbs to the rear brakes to be cleared.

Basically I think if you set the suspension high you will have no further problems (need to run engine or have a working accumulator which only holds 1/2 litre max which is just before it fails)

mrjohnson · Post by **mrjohnson** » 24 Oct 2006, 14:10

Thanks Jeremy.

That did the trick.

Regards,

Martyn