New Master cylinder weeping in back around piston

[Tim Ayers]

Finished the brakes on my AV8 project. Bleeding went really well and took under an hour to get a really firm pedal. No real leaks and just a two fittings needed to be wrenched tighter to stop weeping.

Today, I noticed a small drop under the US made Wagner master cylinder. I pull the plunger boot back and I can see fluid in the boot and wetness around the back of the piston. Cleaned it off, pumped the brakes a few times and it seemed it stop. An hour later it is weeping again.

I know that brake fluid swells seals, so it is concerning me that its weeping a day after bleeding the brakes. At this point, I don't think it's going to stop on it's own.

I have a few options: I have M/C rebuild kits. I could bleed out the fluid, change the piston and plunger from the back side without breaking open the lines. Refill and bleed and see if that fixes it.

Or, I also have a Chinese made Wagner that seems like a newer design. I could put that one in, but I'd rather keep the US made if possible.

I'm using Dot 3 fluid.

Thoughts?

Thanks,

Tim