[TheBUC]

Replace the flex hose, they collapse inside not letting the brake fluid return.

 

[TheBUC]

"Replace the flex hose, they collapse inside not letting the brake fluid return"

+1 Seems pretty new to be this, but I've seen it more than once.

I've been replacing cheap Chinese transmission cooler lines on 2009 to 2011 GM trucks that are rotted to the point they leak, so flex lines don't surprise me anymore. I see a lot of this in my shop and you never use to.