Here's a general outline of the process. Specific details will vary depending on your truck's configuration (single or dual rear wheels, etc.):
1. Preparation:
* Safety First: Disconnect the negative battery terminal. Wear safety glasses and gloves. Have a well-ventilated workspace.
* Gather Tools: You'll need:
* Wrench set (metric) – various sizes to fit the brake line nuts and fittings.
* Flare nut wrench set – essential for preventing damage to the brake lines.
* Pipe wrench (optional, but helpful for stubborn lines).
* Brake line tubing cutter – for cleanly cutting the new line.
* Double flaring tool – to create the proper flare on the ends of the new brake line.
* Brake fluid – DOT 3 or DOT 4, as specified for your truck.
* Shop rags or paper towels.
* Jack and jack stands – to safely lift the truck.
* Wheel chocks.
* New brake line – Make sure you get the correct length and type. A local auto parts store can help with this. They often have diagrams.
* Locate the Leaking/Damaged Line: Carefully inspect the entire rear brake line system to pinpoint the area needing replacement.
* Drain Brake Fluid: Before disconnecting any lines, open the bleeder valve on the caliper(s) to relieve pressure in the system. This helps prevent brake fluid from spraying out.
2. Removing the Old Line:
* Secure the Truck: Safely lift and support the truck using jack stands.
* Access the Line: You'll likely need to remove some components to access the section of brake line to be replaced. This could involve removing wheels, parts of the exhaust system, or other underbody components. Refer to a repair manual for your specific year and model.
* Disconnect Fittings: Carefully loosen and remove the nuts connecting the damaged line to the other components (e.g., the proportioning valve, flexible brake lines to the calipers). Use a flare nut wrench to avoid damaging the fittings.
* Remove the Old Line: Once disconnected, carefully remove the old brake line. It may be necessary to cut it in sections to maneuver it out.
3. Installing the New Line:
* Measure and Cut: Carefully measure the new brake line to ensure the correct length. Use the brake line tubing cutter to make a clean, square cut.
* Flare the Ends: Using the double flaring tool, create a proper flare on both ends of the new line. This is crucial for a leak-free connection. Improper flaring is a common cause of brake line failures.
* Connect the New Line: Carefully connect the new brake line to the fittings, tightening the nuts securely but without over-tightening. Again, use a flare nut wrench.
* Double Check Connections: Visually inspect all connections for leaks.
4. Bleeding the Brakes:
* Reconnect Battery: Reconnect the negative battery terminal.
* Bleed the Brakes: Once the lines are installed and inspected, bleed the brakes to remove any air that may have entered the system. This usually requires two people: one to pump the brake pedal and one to open and close the bleeder valves on each caliper. Refer to your repair manual for the correct bleeding sequence.
5. Final Checks:
* Inspect for Leaks: After bleeding the brakes, carefully inspect all connections again for any leaks.
* Test Drive: Take a short test drive to check the brakes. The pedal should feel firm and responsive.
Crucial Considerations:
* Repair Manual: A factory service manual for your 1991 Chevy Silverado is highly recommended. It will provide detailed diagrams and instructions specific to your truck.
* Professional Help: If you're not comfortable with any step of this process, take your truck to a qualified mechanic. Brake system failure can have serious consequences.
This is a simplified overview. Working with brake lines requires precision and expertise. Consult a repair manual and consider seeking professional assistance if needed. Improperly installed brake lines are extremely dangerous.
