Replace a single damaged or corroded brake line on the 2012-2018 Jeep Wrangler JK with 3.6L V6 engine, including proper flaring, routing, and complete brake system bleeding.

Warnings

Tools required

Parts

• Pre-formed brake line (specify front/rear and side) × 1 — Use OEM specification or pre-bent aftermarket line
• Brake line retaining clips × 2 — Replace any damaged clips
• Copper crush washers (if banjo fittings used) × 2 — Use OEM specification

Fluids

• Mopar DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level, stable ground and engage parking brake
2. Place wheel chocks behind wheels that will remain on ground
3. Turn off engine and remove key from ignition
4. Pump brake pedal 25-30 times to depressurize brake system and ABS accumulator
5. Raise and support vehicle with jack stands at appropriate frame lift points
6. Remove wheel(s) if brake line is located near wheel well or behind wheel
7. Locate damaged brake line and identify upstream/downstream connection points
8. Apply penetrating oil to line fittings and allow 10-15 minutes to soak if corrosion is present
9. Place catch pan under work area to collect brake fluid
10. Have new brake line ready - verify correct length, fittings, and routing before removal

Procedure

1. 1

   Remove damaged brake line from upstream fitting
   Using a line wrench (not open-end wrench), carefully loosen the upstream brake line fitting. Hold the component fitting stationary with a second wrench to prevent twisting the component. Brake fluid will drain from the line - direct into catch pan. Once loose, unthread by hand and remove line from fitting. Immediately plug the open port with a rubber cap or clean bolt to minimize fluid loss and prevent contamination.
2. 2

   Remove damaged brake line from downstream fitting
   Using line wrench, loosen the downstream fitting while holding the component stationary. Allow brake fluid to drain into catch pan. Remove line completely from vehicle. Note the routing path, bracket locations, and any clips securing the line - take photos if helpful for reference during installation.
3. 3

   Remove line retaining clips and brackets
   Remove any retaining clips, brackets, or fasteners that secured the old brake line to the frame or body. Inspect clips for damage or corrosion and replace as needed. Clean mounting surfaces with wire brush if rust is present.
4. 4

   Prepare new brake line
   If using pre-formed line, verify correct fitment by test-fitting to both connection points without tightening. If using bulk line, measure and cut to appropriate length allowing extra material for bends and flares. Use tubing cutter for clean, square cuts - do not use hacksaw unless absolutely necessary. Deburr cut ends inside and outside with deburring tool or file.
   ⚠Line must have sufficient slack to prevent stress on fittings during suspension travel, but not so much that it contacts moving components or sharp edges.
5. 5

   Create double flares on new line
   If fabricating line from bulk stock, install fittings/nuts onto line before flaring. Using double-flare tool, create SAE J1047 compliant double flares on both ends. Clamp line in flaring tool at correct height per tool instructions. Form the initial bubble, then complete the double flare. Inspect flare for cracks, splits, or incomplete formation - remake if any defects are visible. Flare surface must be smooth and concentric.
   ⚠️A defective flare will cause brake failure under pressure. Inspect carefully and remake any questionable flares.
6. 6

   Route and install new brake line
   Route new brake line along original path, ensuring it does not contact exhaust components, sharp edges, or moving suspension parts. Maintain minimum 1 inch clearance from exhaust and ensure line cannot contact tire or wheel during full suspension travel and steering lock. Install retaining clips loosely at bracket locations.
7. 7

   Connect upstream fitting
   Thread upstream fitting into component by hand, ensuring it starts easily without cross-threading. If fitting resists or feels tight, back out and restart - do not force. Once hand-tight, use line wrench to tighten to specification. Hold component fitting stationary with backup wrench to prevent component damage.
   ⚠Over-torquing will damage flare and cause leaks. Under-torquing will allow fitting to vibrate loose. Use torque wrench for all brake line fittings.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
8. 8

   Connect downstream fitting
   Thread downstream fitting into component by hand until seated, then torque to specification using line wrench and backup wrench. Verify line has proper routing with no kinks, sharp bends (minimum 3-inch radius), or contact points with vehicle components.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
9. 9

   Secure line with retaining clips
   Tighten all retaining clips and brackets to secure line in proper position. Ensure clips hold line firmly but do not deform or crimp the tubing. Verify adequate clearance from all moving parts, suspension travel limits, and heat sources.
10. 10

    Refill brake fluid reservoir
    Open brake fluid reservoir and fill to MAX line with fresh DOT 4 brake fluid from sealed container. Do not reuse old brake fluid. Keep reservoir filled above MIN line throughout bleeding process to prevent introducing air into system.
    ⚠Never allow brake fluid reservoir to run dry during bleeding - this will introduce air into ABS module requiring special scan tool to purge.
11. 11

    Bleed brake system
    Bleed brake system starting with wheel furthest from master cylinder (typically right rear), then left rear, right front, left front. For each wheel: attach clear tubing to bleeder screw and submerge other end in catch bottle with clean brake fluid. Have assistant pump brake pedal 5-6 times and hold pressure. Open bleeder screw with wrench - fluid and air will flow out. Close bleeder before pedal reaches floor. Repeat until fluid flows clear without bubbles. Torque bleeder screw to specification. Maintain fluid level in reservoir throughout process.
    ⚠️Incomplete bleeding will result in soft brake pedal and reduced braking ability. Continue bleeding each wheel until absolutely no air bubbles are visible in discharged fluid.
    Torque spec

    Bleeder Screw16 Nm (12 lb-ft)
12. 12

    Install wheel and torque lug nuts
    If wheel was removed, install wheel onto hub. Thread all lug nuts by hand, then torque in star pattern to specification. Lower vehicle from jack stands and perform final torque check with vehicle weight on ground.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)

Reassembly

1. Top off brake fluid reservoir to MAX line with fresh DOT 4 fluid
2. Verify all fittings are torqued correctly and all retaining clips are secured
3. Clean any spilled brake fluid from painted surfaces immediately with water
4. Dispose of used brake fluid according to local environmental regulations

Verification

• With engine off, pump brake pedal repeatedly - pedal should become firm and hold steady pressure without sinking
• Inspect all fittings for signs of brake fluid seepage or dripping - any wetness indicates leak requiring immediate correction
• Start engine and verify brake warning light extinguishes (ABS light may require brief driving to clear)
• Perform controlled brake test in safe area at low speed (15-20 mph) - verify firm pedal feel and straight-line stopping without pulling
• Perform final leak inspection at all fittings after brake test - check for wetness indicating leaks under pressure
• Test drive at progressively higher speeds in safe area, verifying normal brake operation and pedal feel
• After first 50-100 miles, re-inspect all fittings for leaks and verify brake pedal feel remains firm
• If pedal feels soft, spongy, or sinks under steady pressure, DO NOT DRIVE - repeat bleeding procedure or seek professional service

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