Jeep Wagoneer/Commando/Cherokee 1984-1998

Master Cylinder

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Removal & Installation



Non-ABS Equipped Models

See Figures 1, 2 and 3

  1. Disconnect and plug the brake lines.
  2.  
  3. Remove the combination valve (if necessary).
  4.  
  5. Remove all attaching bolts and nuts, and lift the assembly from the vehicle.
  6.  

To install:
  1. Remove the protective cover from the end of the primary piston (if necessary).
  2.  
  3. Clean the cylinder mounting surface on the booster.
  4.  
  5. Install the master cylinder onto the brake booster studs.
  6.  
  7. Install the nuts and tighten to 18 ft. lbs. (25 Nm).
  8.  
  9. Connect the brake lines, fill the reservoir and bleed the brake system.
  10.  



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Fig. Fig. 1: Loosening the brake lines using a backup wrench



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Fig. Fig. 2: Removing the master cylinder-to-booster retaining nuts



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Fig. Fig. 3: Removing the master cylinder from the vehicle

ABS Equipped Models

See Figures 4, 5, 6, 7, 8, 9, 10 and 11

This procedure applies to all models equipped with ABS except for 1989-91 Jeep models which are equipped with a Bendix anti-lock brake system. Refer to that removal procedure later in this section.



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Fig. Fig. 4: Disengage the wiring harness connector from the pedal travel sensor, located on the power booster



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Fig. Fig. 5: Before disconnecting any brake lines to the master cylinder, suck out as much of the brake fluid as possible from the reservoir



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Fig. Fig. 6: Loosen the hose clamps and disconnect the brake fluid reservoir-to-HCU hoses

  1. Disengage the pedal travel sensor wires and remove the air cleaner.
  2.  
  3. Before disconnecting any brake lines, suck out as much of the brake fluid as possible from the reservoir.
  4.  
  5. Remove the clamps that secure the reservoir hoses to the Hydraulic Control Unit (HCU) pipes.
  6.  
  7. Drain the fluid into a container and discard the fluid.
  8.  
  9. Pump the brake pedal to exhaust all vacuum from the booster.
  10.  



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Fig. Fig. 7: Using a flare nut wrench, loosen the brake line fittings at the master cylinder ...



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Fig. Fig. 8: ... then remove the fitting and disconnect the brake line



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Fig. Fig. 9: Remove the mounting bolt securing the combination valve bracket to the master cylinder

  1. Disengage the brake lines and the combination valve bracket bolt at the master cylinder.
  2.  
  3. Unfasten the master cylinder attaching bolts and remove the master cylinder from the vehicle.
  4.  



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Fig. Fig. 10: Using a box wrench, remove the master cylinder mounting nuts



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Fig. Fig. 11: Carefully pull the brake master cylinder assembly off of the power booster and out of the vehicle

To install:
  1. If installing a new master cylinder, bleed the cylinder on a bench before installation.
  2.  
  3. Install the master cylinder in position and engage the reservoir hoses to the HCU pipes.
  4.  
  5. Tighten the master cylinder retaining bolts to 25 ft. lbs. (34 Nm) and connect the brake lines.
  6.  
  7. Install the combination valve and bracket bolt (if removed).
  8.  
  9. Connect the sensor wires and fill the reservoir.
  10.  
  11. Bleed the brakes. Refer to the procedure outlined later in this section.
  12.  
  13. Install the air cleaner and test drive the vehicle to verify proper brake operation.
  14.  

 
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