28-DEC-08
Sometimes (when changing the brake calipers on disk brakes, or changing wheel cylinders on drum brake systems) the mechanic will clamp a vise grip pliers on the rubber hose to prevent hydraulic fluid from dripping out. This can break the internal fiber lining in the rubber hose. Then the fluid flow can be blocked. When you press the brake pedal, fluid may not flow to the wheel or wheels. As you press harder, the fluid may suddenly flow through the line, causing the brakes to suddenly activate.
Or an even more likely problem, your brakes drag (stay on) and get hot, because the fluid cannot flow back to the master cylinder when you release the brake pedal. In other words, when you press the brake you force fluid through a partially blocked rubber hose. But the return of the fluid (backwards through the rubber hose) is caused not by pressure, but just by equilibrium, a balancing act. Well, if the line (rubber hose) is blocked, the fluid stays in the caliper or wheel cylinder, and the brake is still on, and the brake gets hot.
Ken
Camas, Washington
[email protected]
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