Mitsubishi Car 1999-05

Power Brake Booster

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Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Siphon the brake fluid from the master cylinder reservoir.
  4.  


CAUTION
Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with the eyes and wash your hands thoroughly after handling brake fluid. If you do get brake fluid in your eyes, flush your eyes with clean, running water for 15 minutes. If eye irritation persists, or if you have taken brake fluid internally, IMMEDIATELY seek medical assistance.

  1. Remove and relocate the air conditioning relay box and the solenoid valve located at the power brake unit.
  2.  
  3. Disconnect the vacuum hose from the booster by pulling it straight off. Prying off the vacuum hose could damage the check valve installed in the brake booster vacuum hose.
  4.  
  5. Detach the electrical harness connector from the brake level sensor.
  6.  
  7. Remove the nuts attaching the master cylinder to the booster and remove the master cylinder and position aside. If necessary, disconnect and plug the brake fluid lines at the master cylinder.
  8.  
  9. From inside the passenger compartment, remove the cotter pin and clevis pin that secures the booster pushrod to the brake pedal.
  10.  
  11. From inside the vehicle, remove the nuts that attach the booster to the dash panel. Remove the brake booster from the engine compartment.
  12.  



Click image to see an enlarged view

Fig. Exploded view of the power brake booster and related components-most models

To install:

  1. Install the brake booster to the dash panel. From inside the vehicle, install the attaching nuts and tighten to 12 ft. lbs. (17 Nm).
  2.  
  3. Apply grease to the clevis pin and install with washers in place. Install new cotter pin and bend to secure in place.
  4.  
  5. Attach the vacuum hose to the booster fitting.
  6.  
  7. Install the master cylinder assembly to the mounting studs on the brake booster. Install the master cylinder mounting nuts and tighten to 9 ft. lbs. (12 Nm).
  8.  
  9. Reconnect the brake fluid reservoir to the master cylinder, if disconnected. Attach the electrical connector to the brake fluid level sensor.
  10.  
  11. Install the solenoid valve assembly and the relay box, if removed.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Add fluid to the brake fluid reservoir as required.
  16.  


WARNING
Clean, high quality brake fluid is essential to the safe and proper operation of the brake system. You should always buy the highest quality brake fluid that is available. If the brake fluid becomes contaminated, drain and flush the system, then refill the master cylinder with new fluid. Never reuse any brake fluid. Any brake fluid that is removed from the system should be discarded. Also, do not allow any brake fluid to come in contact with a painted surface; it will damage the paint.

  1. Bleed the master cylinder. If after bleeding the master cylinder the brake pedal feels soft, bleed the brake system at all wheels.
  2.  
  3. Check the brake system for proper operation.
  4.  

Testing



System Operation Test
  1. With the engine OFF , pump the brake pedal until the supply vacuum is entirely gone.
  2.  
  3. Put light, steady pressure on the brake pedal.
  4.  
  5. Start the engine and let it idle. If the system is operating correctly, the brake pedal should fall toward the floor if the constant pressure is maintained.
  6.  

Power brake systems may be tested for hydraulic leaks just as ordinary systems are tested.

Vacuum Leak Test
  1. Operate the engine at idle without touching the brake pedal for at least one minute.
  2.  
  3. Turn off the engine and wait one minute.
  4.  
  5. Test for the presence of assist vacuum by depressing the brake pedal and releasing it several times. If vacuum is present in the system, light application will produce less and less pedal travel. If there is no vacuum, air is leaking into the system.
  6.  

 
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