GM Full-Size Trucks 1988-1998 Repair Information

Master Cylinder

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REMOVAL & INSTALLATION



See Figures 1 and 2


WARNING
Clean any master cylinder parts in alcohol or brake fluid. Never use mineral based cleaning solvents such as gasoline, kerosene, carbon tetrachloride, acetone, or paint thinner as these will destroy rubber parts. Do not allow brake fluid to spill on the vehicle's finish, it will remove the paint. Flush the area with water.

  1. Using a clean cloth, wipe the master cylinder and its lines to remove excess dirt and then place cloths under the unit to absorb any spilled fluid.
  2.  
  3. Remove the hydraulic lines from the master cylinder using a flare nut wrench and plug the outlets to prevent the entrance of foreign material. On trucks with ABS, disconnect the lines at the isolation/dump valve.
  4.  
  5. Remove the master cylinder attaching bolts or, on trucks with ABS, the attaching bolts from the isolation/dump valve, and remove the master cylinder from the brake booster, or, on trucks with manual brakes, the firewall.
  6.  


CAUTION
On trucks with ABS, never let brake fluid or your skin touch the ECU electrical connections! Also, never let the isolation/dump valve hang by its wiring!

To install:
  1. Position the master cylinder or, on trucks with ABS the master cylinder and isolation/dump valve, on the booster or firewall. Tighten the nuts to 20 ft. lbs. (27 Nm).
  2.  
  3. Connect the brake lines and tighten them to 13 ft. lbs. (17 Nm) on R/V series and 18 ft. lbs. (24 Nm) on C/K models. Fill the master cylinder reservoirs to the proper levels.
  4.  
  5. Bleed the brake system.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Remove the hydraulic lines from the master cylinder using a line wrench



Click image to see an enlarged view

Fig. Fig. 2: Unfasten the master cylinder attaching bolts and remove the master cylinder

 
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