Notice: Hydraulic brake systems use two distinct and incompatible fluids. Power steering fluid is used in the hydraulic brake booster system. Brake fluid is used in the master cylinder and brake pipes. Use extreme care when selecting brake system fluids, or seal damage can result. Refer to General Information to select the correct fluid.

Some models use a hydraulic power brake booster to provide assist. The hydraulic power brake booster uses fluid pressure from the power steering pump to provide power assist. The power brake booster is located on the left front cowl and serves as the mounting surface for the brake master cylinder.

The power steering pump supplies hydraulic pressure to operate the power brake booster. The pump is belt driven and mounts to the engine. The power steering pump provides continuous flow of fluid to the power brake booster any time the engine is running. For more information regarding the power steering pump, refer to Power Steering System.

Three flexible hoses route the power steering fluid through the hydraulic power brake booster system. One hose supplies pressurized fluid from the power steering pump. Another hose routed pressurized fluid from the power brake booster to the steering gear for the purpose of power assisted steering. The last hose returns fluid to the power steering pump. Refer to Power Steering Hose in Power Steering System.

The hydraulic brake booster system does not use special fluids. Care must be taken to use the correct fluids. The brake cylinder and brake system uses Delco Supreme 11® Brake Fluid GM P/N 12377967, or an equivalent DOT-3 motor vehicle brake fluid, while the hydraulic power brake booster used power steering fluid.

Do not reuse brake system fluids. Do not mix power steering fluid with hydraulic brake fluid. Fluid contamination can result in swelling and deterioration of rubber parts. This can lead to reduced brake performance and the eventual loss of braking capability. If the fluid is contaminated, flush the hydraulic brake booster system with clean power steering fluid. Refer to Flushing the Hydraulic Booster System. Booster component bench servicing should be done in a clean work area separate from the brake servicing area. Do not use the same containers for brake and power steering fluids.

Contamination of the fluid in the power steering and hydraulic power brake booster system requires flushing. Contaminated fluid in the power brake booster system can cause rubber deterioration. Flushing involves draining the old fluid and replacing the old fluid with clean fluid. Clean and flush the hydraulic power brake booster system when replacing the power steering pump. Metal shavings from a worn power steering pump often contaminate the booster system. Disassemble the power brake booster front housing. clean the power brake booster front housing. Replace all seals and O-ring seals. Remove the pipes and hoses. Blow clean the pipes and hoses of all metal shavings.