Mazda Trucks 1994-1998 Repair Guide

Brake Master Cylinder



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.


See Figures 1, 2, 3 and 4

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. Fig. 1: Level of brake fluid as measured on the reservoir

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Fig. Fig. 2: 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. All vehicles covered by this guide should 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. Fig. 3: Remove the brake fluid reservoir cap being careful not to allow any contaminants to enter the system

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Fig. Fig. 4: 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.