xj brake bleeding

[kf4anm]

My neighbor gave me a call last night saying he was having trouble getting his brakes bled. I sold my xj1100 but he is still running his. He has a super nice ride and is always tinkering to keep it looking good. He had taken his calipers off to paint them. After re-installation he got the front to bleed fine but had trouble with the rear link system. I went over today to give him a hand. everything was torqued and in order. we could get the pressure to pump up and the line to bleed with no air, but as soon as the valve shut the pedal went back flat. After numerous attempts I am convinced he has a leak somewhere letting air back in. Which of the following sounds more reasonable.

a the copper crush washers on the line banjos have worn out.

b he blew a caliper piston seal when he pushed them back in to resinstall on the disk.

c. The master cylinder has a leak somehow.

Tuesday he is picking up new washers, and bleeder valves. The lines are new stainless. The only connection he messed with was the fittings on the calipers. everything worked perfectly before he dismantled it.

any idears or suggestions on where to look.

Regards
daryl

[John]

Try reverse bleeding the system. It has been discussed here earlier, so you should be able to find some info by using the search tab above.

[Ken Talbot]

I would bet money there is no "leak letting air back in". Rather, I would put money on the bet that there is still air trapped in the system. Keep at it, it has to come out.

[kf4anm]

I will research the reverse bleeding tip. I thought myself it was just air in the lines. we spent about 3 hours and a bottle of dot 4 pushing fluid through. Just when it started to feel good, it would go flat. Thats when I started to suspect a leak.

Thanks again for the response.

Best regards,
Dc