Brake Bleeding Tools & Hydraulic Diagnostics

Why does contaminated brake fluid with absorbed water cause spongy or failing brakes under heavy downhill braking?

Next

 Correct IncorrectBrake fluid is hygroscopic (absorbs water). Absorbed moisture drastically lowers the boiling point. Under heavy braking, the water turns to steam, which is compressible vapor, causing a soft or sinking pedal (vapor lock).

Why does contaminated brake fluid with absorbed water cause spongy or failing brakes under heavy downhill braking?

• Moisture boils into compressible steam vapor, destroying hydraulic line pressure (vapor lock)
• The water freezes into solid ice instantly
• Water turns the brake pads into slippery soap
• It makes the ABS computer think the car is parked