Spongy Pedal

NON-ABS SYSTEMS

NOTE: For ABS systems see Antilock Brake Systems/Testing and Inspection.

CAUSES
- Air is trapped in the hydraulic lines. The spongy feeling is a result of the air being compressed when the brakes are applied. Clean fresh brake fluid is non-compressible and will produce a firm brake pedal.
- Brake fluid is contaminated with water. During prolonged or severe braking, localized brake fluid temperatures can quickly exceed 220 degrees F. Any water in the brake fluid boils off into steam and creates a spongy pedal. As the brakes cool off the steam condenses back into water and the spongy feeling disappears.

WHAT TO CHECK FOR
- Verify that the master-cylinder reservoir is filled with clean fresh brake fluid.

NOTE: If at any time the master-cylinder reservoir has been emptied, the master-cylinder will need to be bled.

- Verify that the shoes/linings are properly adjusted, adjust if necessary.
- Bleed the brakes at all four wheels.

NOTE: Refill the master-cylinder after bleeding at each wheel.

- If the brake pedal is still soft or spongy, flush the hydraulics and replace with clean fresh brake fluid, then bleed the brakes at all four wheels again.