Hello all! I’ve recently replaced my master cylinder, booster, and pedal, and the “supply” line at the cylinder will not stop weeping. It’s not a severe weep, it doesn’t drip unless you pump the pedal. What could be wrong? I’ve already positioned, and repositioned the line, and it won’t cease. It seems to be weeping behind the nut (where the line enters, pointed at)

any help is grateful, thank you.

 

Today's replacement parts are mostly junk. Might have to try several lines before one seals properly.

 

I agree, but the line is OEM. It came out of a ‘95 2500 that was not leaking.

 

If you have enough line, you could cut off the end, and re-flare it.... or, try and tighten it a bit more, to see if it will stop leaking.

 

It was actually leaking at the threads. I used Teflon to seal it temporarily. I think it’s the master cylinder itself. When I got it it looked pretty sketchy like it was a return/reman despite being labeled as “new”

 

With a flare, the threads shouldn’t see any fluid.
The point of sealing is the inside face of the flare against the seat... the nut takes up on the outside of the flare.

 

Try tightening the flare nut some more until it stops leaking. I had the same issue when I replaced all of my brake lines with stainless steel brake lines.