Here's a general outline; specifics may vary slightly depending on which lines you're replacing:
1. Preparation and Safety:
* Safety First: Wear safety glasses and gloves. Work in a well-ventilated area.
* Gather Tools: You'll need:
* Line wrench set (for various sizes of brake line nuts)
* Flare nut wrench (especially helpful for avoiding damage)
* Pipe wrench (for stubborn nuts)
* Tubing cutter (for clean cuts on new lines)
* Brake line flaring tool (if you're not using pre-flared lines)
* New brake lines (match the original lines in size and material)
* Double-flare tubing (unless you're using pre-flared lines)
* Brake fluid
* Drain pan
* Rags
* Jack and jack stands (securely support the vehicle)
* Wheel chocks
* Consult a Repair Manual: A Haynes or Chilton repair manual specific to your 1991 Buick LeSabre will provide detailed diagrams and instructions. This is highly recommended.
* Bleed the Brakes: After replacing the lines, you *must* bleed the brakes to remove air from the system.
2. Procedure:
* Disconnect the Battery: This is a standard safety precaution to prevent accidental shorts.
* Locate the Leaking or Damaged Line: Pinpoint the section needing replacement.
* Drain Brake Fluid: Partially drain the brake fluid reservoir to create space for any fluid displaced during the line replacement. This prevents overflow.
* Disconnect the Old Line: Carefully disconnect the old brake line from its fittings. This often involves using line wrenches or flare nut wrenches to avoid rounding off the nuts. Take note of how everything is connected for reassembly. Take pictures if it helps.
* Remove the Old Line: Once disconnected, remove the old brake line section. You may need to carefully loosen clamps or brackets holding it in place.
* Prepare the New Line: If using pre-flared lines, you are good to go. If using double-flare tubing, you will need to use the double-flare tool to create the necessary flares on the ends of the new tubing.
* Install the New Line: Carefully route the new line, following the path of the old line. Secure it with the original clamps or brackets.
* Connect the New Line: Connect the new line to the fittings, ensuring tight connections. Use a torque wrench if possible to avoid over-tightening.
* Reconnect the Battery: Reconnect the battery terminals.
* Bleed the Brakes: This is extremely important. Use a brake bleeder kit and follow the proper bleeding sequence (usually starting with the furthest wheel from the master cylinder and working your way closer). Have a helper pump the brake pedal while you open and close the bleeder valves. Continue until you get a steady stream of fluid without air bubbles.
* Check for Leaks: After bleeding the brakes, carefully check all connections for leaks.
Important Considerations:
* Rust: On older vehicles like a 1991 LeSabre, rust can make removing lines very difficult. Use penetrating oil to help loosen rusted nuts. Be prepared for potential breakage of lines or fittings.
* Proper Flare: A poorly flared line will leak. Ensure your flares are properly made if you're flaring tubing yourself.
* Correct Routing: Improper routing can lead to restricted movement, interference with other components, or damage to the lines.
* ABS System: If your LeSabre has an Anti-lock Braking System (ABS), working on the brake lines can be more complex. Consult a repair manual specifically for ABS systems.
Disclaimer: This information is for general guidance only. Improper repair of brake lines can result in serious injury or death. If you are not comfortable performing this repair, please take your vehicle to a qualified mechanic. Always consult a repair manual specific to your vehicle's year and model before starting any repair work.
