Hydraulic System

An inspection of the brake hydraulic system begins with a brake fluid level check. If the brake fluid level is below the line in the brake master cylinder reservoir, add the required amount of Ford High Performance DOT 3 Brake Fluid C6AZ-19542-AA or equivalent DOT 3 fluid meeting Ford specification ESA-M6C25-A.

Brake Master Cylinder

When in the brake master cylinder area, check the brake lines and brake master cylinder mounting. The brake lines and attaching nuts must be tight. The brake line fittings must not show any signs of leakage. Tighten the brake lines at the brake master cylinder (2140) to 14.8-20.2 Nm (11-14 lb-ft) for the fitting at the rear port and 21.2-28.8 Nm (16-21 lb-ft) for the front port.

The following conditions are considered normal and are not indications that the brake master cylinder reservoir is in need of service.

• Low brake fluid level detected without signs of leakage. This condition is caused by displacement of brake fluid from the brake master cylinder reservoir into the front disc brake calipers (2B120) to compensate for normal brake wear. Add brake fluid as needed.
• A momentary or slight squirt of brake fluid from the brake master cylinder reservoir upon application of the brake pedal (2455). This condition is caused by brake fluid displacement through the brake master cylinder reservoir compensating port as the brake master cylinder pistons move forward in the bore when the brakes are applied.
• Slight turbulence in the brake fluid when the brake pedal is released. Turbulence occurs as brake fluid returns to the brake master cylinder after releasing the brakes.
• A trace of brake fluid found on the outside of the power brake booster (2005) below the brake master cylinder mounting flange. This condition results from the lubricating action of the master cylinder wiping seal.

Brake Tubing

Inspect the brake tubes under the vehicle for damage and proper routing. Check the hoses connecting the brake tubes to the disc brake calipers and the rear wheel cylinders (2261) for any signs of damage, cracking or softening. The hose fittings must be tight without signs of leakage.

If signs of leakage are not present but the brake master cylinder is definitely low, evidence of brake fluid leakage may have been washed off by rain or snow because brake fluid is water soluble. To determine if a leak exists, perform the following:

1. Refill the system.

2. Bleed the system.

3. Apply the brakes several times.

4. Examine the system to verify that the brake master cylinder reservoir level is actually dropping.

5. Locate and correct the external leak.

Internal and external leaks are two problems that can affect a brake hydraulic system. The hydraulic brake system will not cause the vehicle to grab, squeal or allow the brake pedal to pulse (except during ABS operation).

In most cases the hydraulic system will not even cause the brakes to drag. The sources of these problems are found elsewhere in the brake system, but it is always a good policy to first check the entire hydraulic system for leaks before continuing to diagnose any other brake problems.