GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Master Cylinder



When adding or replacing the brake fluid, always use a top quality fluid, such as Delco Supreme II or DOT-3. DO NOT allow the brake fluid container or master cylinder reservoir to remain open for long periods of time; brake fluid absorbs moisture from the air, reducing its effectiveness and causing corrosion in the lines. General Motors recommends that silicone brake fluid (DOT 5) should NOT be used in the brake system. Damage to the rubber parts may result.


See Figures 1 and 2

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Fig. Fig. 1: Use a cloth to clean the dirt and debris from the cover

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Fig. Fig. 2: Add brake fluid until the proper level is reached, according to the marks on the side of the reservoir. A turkey baster is helpful here

The master cylinder (located in the left rear section of the engine compartment) consists of an aluminum body and a translucent nylon reservoir with minimum fill indicators. The fluid level of the reservoirs should be kept near the top of the observation windows.

Avoid spilling brake fluid on any of the vehicles painted surfaces, wiring cables or electrical connectors. Brake fluid will damage paint and electrical connections. If any fluid is spilled on the vehicle, flush the area with water to lessen the damage.

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