Brake Line Inspection
Inspect brake lines for kinks, rust, and just normal wear and tear. If the line is damaged, replace the entire line. Always use brake line that’s approved by the vehicle’s manufacturer (steel line) not copper or a compression fitting. Copper lines can rupture from pressure and fittings can leak. It should be replaced any time it's damaged or rusted to the point that it affects flow or pressure. Visual inspection typically reveals a kink in the line and pressure kits are available to detect internal restrictions.
When a restriction forms in a brake line, the master cylinder creates more than enough pressure to bypass the kink and apply the brake. The problem is the brake caliper or wheel cylinder is unable to create enough pressure to bypass the kink and return the fluid to the master cylinder. This keeps the brake applied at that wheel or wheels resulting in brake drag. If located at a front wheel, the vehicle will pull to the side with the restricted brake line. Take care when touching the parts though, this friction creates great heat and will be felt at the brake rotor or drum.