GM Full-Size Trucks 1988-1998 Repair Information

Brake Master Cylinder

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FLUID RECOMMENDATIONS



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Master cylinder fluid level

Use only Heavy Duty Brake fluid meeting or exceeding DOT 3 standards.

FLUID LEVEL CHECK



See Figures 2 and 3

Chevrolet and GMC trucks are equipped with a dual braking system, allowing a vehicle to be brought to a safe stop in the event of failure in either front or rear brakes. The dual master cylinder has 2 entirely separate reservoirs, one connected to the front brakes and the other connected to the rear brakes. In the event of failure in either portion, the remaining part is not affected. Fluid level in the master cylinder should be checked on a regular basis.

The master cylinder is mounted to the left side of the firewall.

  1. Clean all of the dirt from around the cover of the master cylinder.
  2.  
  3. Be sure that the vehicle is resting on a level surface.
  4.  
  5. Carefully pry the clip from the top of the master cylinder to release the cover. On some later models, just pull up on the tabs.
  6.  
  7. The fluid level should be approximately 1 / 4 in. (6mm) from the top of the master cylinder or at least above the MIN mark. If not, add fluid until the level is correct. Replacement fluid should be Delco Supreme No. 11, DOT 3, or its equivalent. It is normal for the fluid level to fall as the disc brake pads wear. If the fluid level in the master cylinder is excessively low, check the brake system for leaks and wear.
  8.  


WARNING
Brake fluid dissolves paint! It also absorbs moisture from the air. Never leave a container or the master cylinder uncovered any longer than necessary!

  1. Install the cover of the master cylinder. On most models there is a rubber gasket under the cover, which fits into two slots on the cover. Be sure that this is seated properly.
  2.  
  3. Push the clip back into place and be sure that it seats in the groove on the top of the cover.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Remove the master cylinder cover



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Fig. Fig. 3: Add brake fluid until the level is correct

 
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