The brake system on your car
starts with the brake master cylinder it is were the brake fluid is pressurized
by the foot pedal. This pedal is actuated by the drivers foot when desired. This
brake master cylinder depend on brake fluid to push hydraulic pressure to be transferred
to the various front or rear wheel to provide
brake pad and shoe friction which in turn slows the wheels from turning. There
are several causes for this condition we have listed the most common below.
Troubleshooting
Check the Brake System Fluid Level - Check the level of
fluid in the brake master cylinder.
It is natural for fluid to be a low if the
front or rear
brake pads-shoes have worn down, but if they are in good condition and the brake
master cylinder reservoir is empty you might have a brake fluid leak somewhere in
the system. Inspect front
brake calipers, rear wheel
cylinders (drums) or
rear brake calipers
and flex hoses front
and rear of vehicle and look for any sign of fluid leakage.
Also check the rear of the brake master cylinder for fluid leaks, if brake fluid
is present the master cylinder seals have failed and the master cylinder needs to
be replaced. Replace any parts that are leaking or show signs of previous leakage.
Refill and bleed the brake system as needed. (Note: if brake fluid has contacted
the brake components i.e. brake pads or brake shoes the brake lining material is
contaminated and must be replaced) If the brake fluid in the reservoir is full proceed
to the next step.
Brake Master Cylinder
Brake Master
Cylinder is Full of Brake Fluid - If upon inspection the brake master
cylinder is full of fluid, the brake master cylinder may be bypassing internally.
This means the seals inside the master cylinder have failed allowing the fluid from
the front of the master cylinder plunger to slip through to the rear of the plunger
and back into the fluid reservoir. Allowing the brake pedal to go to the floor with
out pressurizing brake fluid into the system.
Replace master cylinder
with new unit and bleed system as needed.
Failing Axle Bearings
- The vehicle axle bearing holds the wheel true to the axle shaft while
allowing the wheel to rotate. If the bearing fails it will allow the rotor to move
back and forth, forcing the brake pads inward into the caliper. Then as you apply
the brake pedal it will go to the floor as the caliper fills with fluid. In this
case it may take one or two pumps to the brake pedal to regain normal operation.
Inspect and replace failed axle bearings as needed, finish by bleeding and adjusting
the system.
Air in Brake
System - When brake calipers or rear wheel cylinders fail they can
allow air into the system when the brake pedal is released. Bleed the brake system
by loosening the air bleeder, if air is observed from the bleeder replace the caliper
or wheel cylinder and re-bleed system. This condition is rare but it does happen.
If further technical assistance is needed, our certified car repair technicians
are ready to answer your car questions.
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