GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Brake Master Cylinder

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FLUID RECOMMENDATIONS AND LEVEL CHECK



See Figures 1, 2, 3, 4, 5 and 6

The brake master cylinder is located under the hood, in the left rear section of the engine compartment. It is divided into two sections (reservoirs) and the fluid must be kept within 1 / 4 in. of the top edge of both reservoirs. Some reservoirs will have minimum or maximum fluid level marks on an outer side wall in order to help determine if the fluid is at a proper level. The level should be checked at least every 6,000 miles for 1964-74 vehicles or every 7,500 miles for 1975 and later models.

Any sudden decrease in the level of fluid indicates a possible leak in the system and should be checked immediately.

To check the fluid level, simply pry off the retaining bar and then lift off the top cover of the master cylinder, taking care not to allow any fluid to drip on painted surfaces. When making additions of brake fluid, use only fresh, uncontaminated brake fluid which meets or exceeds DOT-3 standards. Be careful not to spill any brake fluid on painted surfaces, as it will quickly eat the paint. Do not allow the brake fluid container or the master cylinder reservoir to remain open any longer than necessary; brake fluid absorbs moisture from the air, reducing its effectiveness and causing corrosion in the lines.

The reservoir cover on some 1978 and later models may be without a retaining ball. If so, simply pry the cover off with your fingers.



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Fig. Fig. 1: If equipped with a metal cap, carefully pry the retaining bar from the top of the master cylinder reservoir cap



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Fig. Fig. 2: Some master cylinder reservoirs are equipped with a plastic cap



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Fig. Fig. 3: For plastic retaining caps, carefully unsnap the cap from the reservoir using the tabs



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Fig. Fig. 4: If equipped, remove the rubber diaphragm located under the cap



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Fig. Fig. 5: If necessary, add only FRESH, clean DOT-3 brake fluid to the master cylinder reservoir



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Fig. Fig. 6: Brake fluid level should be within 1/4 in. of the reservoir's top edge

 
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