GM Astro/Safari 1985-1996 Repair Guide

Master Cylinder

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The clutch master cylinder is located in the engine compartment, on the left side of the firewall, above the steering column.

REMOVAL & INSTALLATION



See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the clutch master cylinder mounting



Click image to see an enlarged view

Fig. Fig. 2: Clutch hydraulic actuating system and component mounting

  1. Disconnect negative battery cable.
  2.  
  3. Remove hush panel from under the dash.
  4.  
  5. Disconnect pushrod from clutch pedal.
  6.  
  7. Disconnect hydraulic line from the clutch master cylinder using a flare nut wrench.
  8.  
  9. Remove the master cylinder-to-cowl brace nuts. Remove master cylinder and overhaul (if necessary).
  10.  
  11. Using a putty knife, clean the master cylinder and cowl mounting surfaces.
  12.  

To install:
  1. Install the master cylinder-to-cowl brace nuts and master cylinder.
  2.  
  3. Connect hydraulic line to the clutch master cylinder using a flare nut wrench.
  4.  
  5. Connect pushrod to clutch pedal.
  6.  
  7. Install hush panel to the dash.
  8.  
  9. Connect negative battery cable.
  10.  
  11. Tighten the master cylinder-to-cowl brace nuts to 10-15 ft. lbs. (14-20 Nm). Fill master cylinder with clean, fresh hydraulic fluid conforming to DOT 3 specifications.
  12.  
  13. Bleed the hydraulic clutch system and check for leaks.
  14.  

OVERHAUL



See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the clutch master cylinder assembly

  1. Remove the clutch master cylinder assembly from the vehicle.
  2.  
  3. Remove the filler cap and drain the fluid from the master cylinder.
  4.  
  5. Remove the reservoir and seal from the master cylinder. Pull back the dust cover and remove the snapring.
  6.  
  7. Remove the pushrod assembly. Using a block of wood, tap the master cylinder on it to eject the plunger assembly from the cylinder bore.
  8.  
  9. Remove the seal (carefully) from the front of the plunger assembly, ensuring no damage occurs to the plunger surfaces.
  10.  
  11. From the rear of the plunger assembly, remove the spring, the support, the seal and the shim.
  12.  
  13. Using clean brake fluid, clean all of the parts.
  14.  
  15. Inspect the cylinder bore and the plunger for ridges, pitting and/or scratches; the dust cover for wear and cracking; replace the parts if any of the conditions exist.
  16.  

To assemble:
  1. Use new seals, lubricate all of the parts in clean brake fluid, and fit the plunger seal to the plunger.
  2.  
  3. Insert the plunger assembly, valve end leading into the cylinder bore (easing the entrance of the plunger seal).
  4.  
  5. Position the pushrod assembly into the cylinder bore, then install a new snapring to retain the pushrod. Lubricate the inside of the dust cover with Girling® Rubber Grease or equivalent. Install dust cover onto the master cylinder.
  6.  

Be careful not to use any lubricant that will deteriorate rubber dust covers or seals.

  1. Install the master cylinder assembly to the vehicle.
  2.  

 
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