Xantia MOT

[thorter]

On the BX and Xantia, which have LHM mineral oil hydraulics, it does no harm to apply oil to the brake parts. When I had these cars I would apply a drop of oil to the top rear brake pistons where they emerge from the cylinder. This is best done just after an MOT as the tester can confuse it with leakage. Wipe clean before the next MOT, and afterwards re-apply. This regime keeeps the rear brakes working properly more or less indefinitely.

So worth a try before replacing the caliper.

[myglaren]

Have you tried loading the boot and rear seats with lots of heavy stuff to increase the pressure on the rear brakes?
I learned this technique with the GS as the rear brakes could get 'tired' if the car was run with little or no weight on the rear suspension. Always gave it a session prior to MOTs that seemed to help get it through.

[CitroJim]

On the BX and Xantia, which have LHM mineral oil hydraulics, it does no harm to apply oil to the brake parts. When I had these cars I would apply a drop of oil to the top rear brake pistons where they emerge from the cylinder. This is best done just after an MOT as the tester can confuse it with leakage. Wipe clean before the next MOT, and afterwards re-apply. This regime keeeps the rear brakes working properly more or less indefinitely.

So worth a try before replacing the caliper.

That's a very, very good piece of advice, knowing how the caliper is constructed... Maybe before, have the pads out, retract the pistons fully and then give all around where the pistons emerge a very good cleanup...

[thorter]

Yes, a good idea to keep the area as clean as possible, given the absence of gaiters on the pistons. With the pads out, you can put the suspension on high, and use brake pressure to partially eject the pistons. However, be careful not to reach the point where the piston uncovers the sealing ring, so I used to put plywood buffers in place to limit the travel. O rings get pushed along by the pressure, and it can be surprising how they can head for the gap and be extruded and minced if the piston uncovers the seal. Unfortunately it is a long time ago, and I cannot now remember any more detail.

Incidentally, I think that when the height lever is correctly set up, the HIGH position overrides everything else and results in full hydraulic system pressure in the brakes. Therefore, it should not be necessary to load up the rear, though it will not do any harm. When doing citrobics, when at high, pressing the brake pedal should ensure the rear brakes are definitely operated.

[froggy]

Thanks for the great advice, going to do a clean up and pop some oil on the end of the piston. add some weight to the back of the car, cheers! Terry.

[CitroJim]

Fingers crossed Terry!