Brake hoses and lines – inspection and replacement
Inspection
1. Whenever the vehicle is raised and supported securely on jackstands, the rubber hoses which connect the steel brake lines with the front and rear brake assemblies should be inspected for cracks, chafing of the outer cover, leaks, blisters and other damage. These are important and vulnerable parts of the brake system and inspection should be thorough. A light and mirror will be helpful for a complete check. If a hose exhibits any of the above conditions, replace it immediately.
Flexible hose replacement
2. Clean all dirt away from the hose fittings.
3. Using a flare-nut wrench, disconnect the metal brake line from the hose fitting (see illustration). Be careful not to bend the frame bracket or line. If the threaded fitting is corroded, spray it with penetrating oil and allow it to soak in for about 10 minutes, then try again. If you try to break loose a fitting nut that’s frozen, you will kink the metal line, which will then have to be replaced.
8.3 Unscrew the line fitting with a flarenut wrench
4. Disconnect the brake hose bracket from the frame. Immediately plug the metal line to prevent excessive leakage and contamination.
5. Unscrew the banjo bolt at the caliper and remove the hose, discarding the sealing washers on either side of the fitting.
6. Attach the new brake hose to the caliper. Note: When connecting a brake hose to a caliper, always use new sealing washers. Tighten the banjo bolt to the torque listed this Chapter’s Specifications.
7. Connect the other end of the new hose, making sure the hose isn’t kinked or twisted. Fit the metal line to the hose (or hose fitting), then tighten the hose bracket and the brake tube fitting nut securely.
8. Carefully check to make sure the suspension or steering components don’t make contact with the hose. Have an assistant push down on the vehicle while you watch to see whether the hose interferes with suspension operation. If you’re replacing a front hose, have your assistant turn the steering wheel lock-to-lock while you make sure the hose doesn’t interfere with the steering linkage or the steering knuckle.
9. After installation, bleed the brakes (Brake hydraulic system – bleeding). Check the master cylinder fluid level and add fluid as necessary. Carefully test brake operation before returning the vehicle to normal service.
Metal brake lines
10. When replacing brake lines, be sure to use the correct parts. Do not use copper tubing for any brake system components. Purchase steel brake lines from a dealer parts department or auto parts store.
11. Prefabricated brake line, with the tube ends already flared and fittings installed, is available at auto parts stores and dealer parts departments. If it is necessary to bend a line, use a tubing bender to prevent kinking the line.
12. When installing the new line, make sure it’s well supported in the brackets and has plenty of clearance between moving or hot components. Make sure you tighten the fittings securely.
13. After installation, check the master cylinder fluid level and add fluid as necessary. Bleed the brakes (Brake hydraulic system – bleeding). Carefully test brake operation before resuming normal operation.