Brake problem, suggestions wanted...

I've bled my brakes. Many, many times.

I've tied the lever back overnight.

I've tied the lever back overnight, *then* bled the brakes.

Tonight, I've replaced the master cylinder internals, bled the brakes,
and tied the lever back.

I just know that come tomorrow, it'll be the same story: they'll feel
fine to start with, but they'll feel like they're losing pressure by the
time I've got to work. When I leave work tomorrow afternoon, I'll
probably be able to pull the lever right back to the bar.

My guess is that air's getting in somewhere, but where?

Any suggestions for how to cure it? (Preferably not involving £90
deposit and 0% finance, thankyouverymuch.)

 

In yer nipples, son. They bain't be seating roight.

New nipples. Seriously. Don't overtighten 'em.

 

<fx: peers down t-shirt>

Oh, *those* nipples.

Anyway, what leads you to that conclusion? And, if that's the case, how
come the brake fluid doesn't seep out while the lever's tied back?

Gah. Worth a try, I guess. Should have ordered some when I got the
master cylinder rebuild kit.

 

Air is much thinner than oil.

Make sure the hole they are going into is clean.

 

New copper washers as well

 

Do you think I'm made of money?

Anyway, IIRC the ones that were used when the calipers were replaced
were new.