Brake Hydraulics Principles

A vehicle has a hydroboost power brake system. Poor brake performane can be caused by:

• A defective vacuum booster

• Low Engine Vacuum

• Low power steering fluid

• A faulty brake light switch

Which of the following is the most likely cause of a hard brake pedal?

• Low Brake Fluid

• Low Manifold Vacuum

• Worn Brake Pads

• Excessive Rotor Runout

True or False? If a vehicle has a seized caliper it will pull to the side of the seized caliper (ex: Seized left caliper--the vehicle will pull left)

• True

• False

A customer complains about a brake pulsation after the front rotors are replaced. This is most likely caused by which of the following?

• Low Brake Fluid

• Low Engine Vacuum

• Sticking Slide Pins

• Rust between the hub and rotor

A customer complains of a spongy brake pedal. Which of the following is the most likely cause?

• Torn Vacuum Booster Diaphragm

• Sticking Parking Brake Cables

• Air in the Hydraulic System

• Incorrect Brake Pedal Freeplay

A customer states they are experiencing a problem when the vehicle is stopped. The brake pedal slowly sinks all the way to the floor. What is the most likely cause?

• Air in the brake lines

• A torn diaphragm in the brake booster

• Failing master cylinder cup seals

• Seized wheel cylinder

A vehicle with front disc, rear drum brakes is having a problem when braking. The front of the vehicle dips when braking (nose dives) What component is the most likely the cause?

• Proportioning Valve

• Metering Valve

• Brake Booster

• Parking Brake Cable

A technician is replacing a brake line which of the following is NOT correct?

• Brake lines should be double walled steel

• Compression fittings are an acceptable means of repair

• Brake lines are flared using double flare or bubble flare methods

• Brake line fitting are available in standard and metric thread pitches.

Combination Valves contain all of the following except:

• Brake lamp switch

• Brake differential switch

• Proportioning valve

• Metering valve

True or False. Over heated brake fluid can boil and vaporize which will leave vapor pockets in the hydraulic system. This can result in a spongy brake pedal.

• True

• False