Chrysler Full-Size Trucks 1997-2000 Repair Guide

Vacuum Brake Booster

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Vacuum brake boosters are used on all models except those with diesel engines.

REMOVAL & INSTALLATION



  1. Remove the master cylinder.
  2.  
  3. Disconnect the vacuum lines at the booster.
  4.  
  5. Remove the steering column knee bolster for access to the booster mounting nuts, if necessary.
  6.  
  7. Remove the clip securing the booster push rod to the brake pedal.
  8.  
  9. Remove the nuts from the booster mounting studs.
  10.  
  11. Remove the booster, spacer and gaskets from the front cowl panel.
  12.  

To install:


NOTE
If the booster is being replaced, ensure that the replacement unit is identical to the original. Refer to identification code letters stamped on the forward face.

  1. Reverse the removal procedure.
  2.  
  3. Tighten the mounting nuts to 21 ft. lbs. (28 Nm).
  4.  
  5. The remainder of the procedure is the reverse of removal.
  6.  



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Fig. Disconnect the booster rod from the pedal



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Fig. Power brake vacuum booster mounting

TESTING



Vacuum boosters can be checked with a vacuum gauge.

  1. Connect the vacuum gauge to the booster check valve with a short length of hose and a T-fitting (see illustration).
  2.  
  3. Start the engine and allow it to idle for one minute.
  4.  
  5. Check for vacuum at the gauge. If there is no vacuum or the reading is very low, the problem is either the booster or the check valve.
  6.  
  7. Assuming vacuum reading is normal, clamp the hose shut between the vacuum source and the check valve.
  8.  
  9. Stop the engine and observe the gauge. If the vacuum drops more than 1 in. (25mm) Hg within 15 seconds, the booster or check valve is at fault.
  10.  
  11. To test the check valve, proceed as follows:
    1. Disconnect the vacuum hose from the check valve.
    2.  
    3. Remove the check valve and valve seal from the booster.
    4.  
    5. With a hand-operated vacuum pump, apply 15-20 in. (381-508mm) Hg at the large end of the check valve.
    6.  
    7. Vacuum should hold steady. If the gauge indicates vacuum loss, the check valve is faulty and should be replaced.
    8.  

  12.  



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Fig. Vacuum booster test connections



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Fig. Vacuum check valve and seal

 
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