Mazda Trucks 1994-1998 Repair Guide

Master Cylinder

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REMOVAL & INSTALLATION



Navajo and B Series Pick-up Models

See Figures 1 through 8



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Fig. Fig. 1: Cutaway view of the master cylinder assembly


WARNING
Vehicles with 4-wheel anti-lock brakes require an Anti-lock Brake Adapter (T90P-50-ALA) and Jumper (T93T-50-ALA) in order to bleed the master cylinder and the Hydraulic Control Unit (HCU). Failure to do so will trap air in the HCU unit, eventually causing a spongy pedal.

Before performing this procedure, ensure that you have the tools necessary to bleed the master cylinder and the HCU unit. If the tools are not available, you can still perform the procedure. However, you will need to tow the vehicle to a professional garage capable of bleeding the ABS system.

  1. With the engine turned off, push the brake pedal down to expel vacuum from the brake booster system.
  2.  
  3. Disconnect the brake fluid level sensor wire from the reservoir.
  4.  
  5. Disconnect the hydraulic lines (use correct tool, a Line Wrench) from the brake master cylinder.
  6.  
  7. Remove the brake booster-to-master cylinder retaining nuts and lock washers. Remove the master cylinder from the brake booster.
  8.  



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Fig. Fig. 2: To remove the master cylinder, first disconnect the fluid level sensor wire



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Fig. Fig. 3: Next, loosen the fluid line fittings at the master cylinder with a flarenut wrench ...



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Fig. Fig. 4: ... then disconnect the lines



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Fig. Fig. 5: If equipped, remove any bracket retaining nuts ...



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Fig. Fig. 6: ... and pull the bracket from the mounting stud



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Fig. Fig. 7: Remove the master cylinder-to-power booster attaching bolts ...



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Fig. Fig. 8: ... then pull the master cylinder off of the mounting studs and remove it from the vehicle.

To install:
  1. Before installing the master cylinder, check the distance from the outer end of the booster assembly push rod to the front face of the brake booster assembly. Turn the push rod adjusting screw in or out as required to obtain the length shown. Refer to illustration in this Section.
  2.  
  3. Position the master cylinder assembly over the booster push rod and onto the 2 studs on the booster assembly. Install the attaching nuts and lockwashers and tighten to 13-25 ft. lbs. (18-34 Nm).
  4.  
  5. Connect the hydraulic brake system lines to the master cylinder.
  6.  
  7. Bleed the hydraulic brake system (refer to procedure in this Section). Centralize the differential valve. Then, fill the dual master cylinder reservoirs with DOT 3 brake fluid to within 1 / 4 in. (6mm) of the top. Install the gasket and reservoir cover. Roadtest the vehicle for proper operation.
  8.  

When replacing the master cylinder it is best to BENCH BLEED the master cylinder before installing it to the vehicle. Mount the master cylinder into a vise or suitable equivalent (do not damage the cylinder). Fill the cylinder to the correct level with the specified fluid. Block off all the outer brake line holes but one, then, using a long tool such as rod position it in the cylinder to actuate the brake master cylinder. Pump (push tool in and out) the brake master cylinder 3 or 4 times till brake fluid is release out and no air is in the brake fluid. Repeat this procedure until all brake fluid is released out of every hole and no air is expelled.

MPV Models

See Figures 9 and 10



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Fig. Fig. 9: Location of the master cylinder mounting nuts and fluid level sensor connector



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Fig. Fig. 10: Disconnect the brake lines from the master cylinder using a flare nut wrench and a box wrench

  1. Clean all dirt and grease from the master cylinder and lines. Disconnect and cap the brake lines from the master cylinder.
  2.  
  3. Disconnect the fluid level sensor connector.
  4.  
  5. Unbolt and remove the master cylinder from the power booster.
  6.  

To install:
  1. Place the master cylinder in position and loosely install the mounting nuts.
  2.  
  3. Connect the hydraulic lines to the master cylinder, but do not tighten fully at this time. Tighten the master cylinder mounting nuts to 7-12 ft. lbs. (10-16 Nm).
  4.  
  5. Tighten the brake lines.
  6.  
  7. Connect the sensor connector.
  8.  
  9. Fill and properly bleed the brake system. Check the system for proper operation.
  10.  

 
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