I had the same problem with my driver's side caliper. I rebuilt the originals, soaked them in simple green, brake cleaner and rust remover before painting with caliper paint. I thought for sure it would leak from the caliper piston as one was a little beat up but nooooooooooooo, it leaked from the bleeder screw. I tightened the bleeder as much as I could. It leaked. I took it out, cleaned it and re-installed it - still leaked. I replaced it and the replacement bleeder leaked. So, I went online and did some research and found out that grit and grime can accumulate under the bleeder screw port and prevent the bleeder from fully seating. Maybe it was gunk from the brake lines or I didn't clean out the passages in the caliper thoroughly. Well, I pulled the wheel and the bleeder and used a couple of a pipe cleaners and brake cleaner and cleaned out the bleeder screw port. Installed another new bleeder screw and so far it has stopped leaking. Hope this helps.
