Mazda B-Series 1998-06

Master Cylinder

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Fluid Level Check



Brake fluid level and condition is a safety related item and it should be checked ANY TIME the hood is opened. Your vehicle should not use brake fluid rapidly (unless there is a leak in the system), but the level should drop slowly in relation to brake pad wear.



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Fig. Level of brake fluid as measured on the reservoir



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Fig. Be sure to wipe off the brake fluid reservoir cap and surrounding area before opening to ensure that no contaminants enter the hydraulic system

The master cylinder reservoir is located under the hood, on the left side firewall. The vehicle may be equipped with a see-through plastic reservoir. This makes checking the level easy and helps reduce the risk of fluid contamination (since you don't have to expose the fluid by opening the cap to check the level). Fluid should be kept near the FULL line or between the MIN and MAX lines, depending on how the reservoir is marked.



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Fig. Remove the brake fluid reservoir cap being careful not to allow any contaminants to enter the system



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Fig. Top off or fill the brake fluid reservoir to the MAX level

If it becomes necessary to add fluid to the system, take a moment to clean the area around the cap and reservoir. Use a clean rag to wipe away dust and dirt which could enter the reservoir after the cover is removed. If the level of the brake fluid is less than half the volume of the reservoir (and the brake pads are not approaching a replacement point), it is advised that you check the brake system for leaks. Leaks in the hydraulic system often occur at the wheel cylinders.

Fluid Recommendations & Fill




WARNING
BRAKE FLUID EATS PAINT. Take great care not to splash or spill brake fluid on painted surfaces. Should you spill a small amount on the car's finish, don't panic, just flush the area with plenty of water.

When adding fluid to the system ONLY use fresh DOT 3 brake fluid from a sealed container. DOT 3 brake fluid will absorb moisture when it is exposed to the atmosphere, which will lower its boiling point. A container that has been opened once, closed and placed on a shelf will allow enough moisture to enter over time to contaminate the fluid within. If your brake fluid is contaminated with water, you could boil the brake fluid under hard braking and loose all/some of the brake system. Don't take the risk, buy fresh brake fluid whenever you must add to the system.

Removal & Installation





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



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



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Fig. ... then disconnect the lines



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



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



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



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Fig. ... 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.

 
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