I've been having some problems with my brakes, and I asked my mechanic if he would be willing to perform a "line-lock test" to help determine the problem. A line-lock test involves clamping off each brake line to keep brake fluid from flowing through. If all lines are clamped, the pedal should be high and hard.
Anyway, the mechanic said that he would never clamp brake lines because they have metal mesh inside of them and he would be worried he would crimp the metal, or at the very least create a weak spot in the line where a bulge or even burst could occur.
Can anyone else weigh in on this debate? I'm planning to take my car to him this afternoon - so quick response would be helpful! Thanks!