Ford Mustang/Capri 1979-1988 Repair Guide

Brake Master Cylinder



Use only Heavy Duty Brake Fluid meeting DOT 3 specifications. Never reuse old brake fluid.

Be careful to avoid spilling any brake fluid on painted surfaces, because the paint coat will become discolored or damaged.


The brake fluid in the master cylinder should be checked every 6 months/6,000 miles.

A slight drop in fluid level is normal as brake pads wear. However, if the level of the brake fluid is less than half the volume of the reservoir, it is advisable to check the brake system for leaks. Leaks in the hydraulic brake system most commonly occur at the wheel cylinders.

Cast Iron Reservoir

See Figures 1, 2 and 3

Click image to see an enlarged view

Fig. Fig. 1: Prying off the master cylinder retaining wire

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Fig. Fig. 2: After cleaning any dirt, remove the master cylinder cover and gasket. Note how the bellows expand to displace a low fluid level.

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Fig. Fig. 3: Add new, clean brake fluid, if necessary, to fill the reservoir to the proper level

  1. Park the vehicle on a level surface and open the hood.
  3. Pry the retaining spring bar holding the cover onto the master cylinder to one side.
  5. Clean any dirt from the sides and top of the cover before removal. Remove the master cylinder cover and gasket.
  7. Add fluid, if necessary, to within 1 / 4 in. of the top of the reservoir, or to the full level indicator (on models so equipped).
  9. Push the gasket bellows back into the cover. Reinstall the gasket and cover and reposition the retaining spring bar.

Plastic Reservoir

Check the fluid level on the side of the reservoir. If fluid is required, remove the filler cap and gasket from the master cylinder. Fill the reservoir to the full line in the reservoir. Install the filler cap, making sure the gasket is properly seated in the cap.