Leaking rear brake union

[valerie]

Hi,
I have just replaced the rear brake pipes with some I bought from another citroen enthusiast, about 10 years ago.

I have never had any problems with leaking unions until now.

The rear right brake pipe union leaks fluid, at the disc brake end.

I've taken it off, refitted it a few times, tried a different seal rubber, to no avail.

Fluid appears to be coming out from between the pipe and the union.

I had to remove the caliper, and apply some heat before using a pipe wrench to get the old union undone.

I used the same procedure on the other side. which is fine.

Any ideas, anyone?

[Kaapelimies]

Maybe the pipe is not deep enough in the caliper hole, so it does not seal right. Or you have the old pipe cut in deep in the hole? Check without the seal that the new pipe goes deep enough.

[white exec]

Good advice.
Important that the end of the steel pipe goes fully into the caliper (or hydraulic unit) drilling, so that the rubber seal can compress. If the pipe comes up against the shoulder of the drilling, the joint will tighten, but the seal will not be compressed.
.

Essential that the pipe is not inserted at any sort of angle.

[valerie]

Many thanks, i'll try removing a little bit off the end of the pipe, and see if that works.

[Kaapelimies]

Don't mess with it, then it will certainly leak! Find out why it's not deep enough. You need the brakes, don't destroy them.

[valerie]

ok, it seemed to be the threads. I re-threaded them using my tap and die set.
put everything back together, no leaks, voila!

[white exec]

Good result.
Those sleeved joints are extraordinarily good at handling exteremely high pressures, provided that everything lines up, and the pipe end enters the drilling in the fitting (to centralise it). When tightened, the rubber fills up the space, and actually improves its seal when under hydraulic pressure. Something Citroen got really right, and decades ago.
Glad yours is sorted.