Brake Master Cylinder Leak

I’m having a problem with leaks from the new brake master cylinder. Here's the sequence of events.

1. Installed the new master cylinder a while ago. Didn't fill it yet.

2. Took it off later to bench bleed, reinstalled and it leaked. I tried tightening the snot out of it (banjo bolts to master cylinder with crush washers) but it still leaked. I thought the problem was that I shouldn't have reused the crush washers.

3. Ordered new banjo bolts and crush washers. Reinstalled. Tightened to what seemed correct. I seated them down, gave a little extra, but didn't try to kill them.

4. Still leaked. Gave it another 1/4 turn. Still leaks.

I don’t know if I damaged the master cylinder threads when I tightened the snot out of it initially (but I never felt it strip) or haven't tightened it enough because I am worried about damaging it.

So, do I tighten it down a little more or remove the banjo bolts, but four more new crush washers, and use some oil resistant thread sealant. Or other suggestion? Thanks.

 

I had the exact same problem with one of my banjo bolts. Is yours leaking from one or both? Mine is Herm conversion I bought from a vendor. I pulled mine apart and cleaned the surface of the washers, bolts, and master cylinder with brake cleaner. Then I reassembled. I had to REALLY tighten one of them but it finally stopped. I think they can take more torque than you realize.

 

Possibly the copper washers need to be annealed to soften them? Heat to red heat, then quench in water.

 

Hate to say it,,,,,,,I had the exact same master cylinder (mine from Kaiser Willys) and the exact same leaking issue (both banjo bolts)! Went thru the exact same "logic process", asking myself the same questions, tightened the heck out of it to a point of concern snapped fasteners. Finally just gave up and moved on, since there was plenty of other repairs required on my jeep before it would ever see pavement. When I finally made it back around to the brake system, incredibly it had stopped leaking! Noticed a little rust around those fittings, but other than that it just "stopped leaking". Possibly that small amount of corrosion sealed it up? Have about 150 miles of back road driving on it now and so far so good!

 

Make sure there are no radial scratches on the MC, Washers, or Bolt. These will cause a leak path.
Cleanliness is important too. A hair under the Washer will cause a leak

 

This. Have had to do it tons of times.

 

This