Automobile & Light Truck Certification Test A5 BrakesHydraulic System Diagnosis and RepairHard
A technician is performing a manual brake bleed on a vehicle. After bleeding the right rear, left rear, and right front calipers, they move to the left front. The pedal feels firm, but no fluid comes out when the left front bleeder screw is opened. Which of the following is the most likely cause?
- AAn internal master cylinder leak
- BA clogged bleeder screw
- CA seized caliper piston
- DA restricted brake line to the left front caliper
Show answer & explanationAnswer & explanation
Correct answer: D. A restricted brake line to the left front caliper
If the pedal feels firm but no fluid comes out, it indicates that pressure is being built up by the master cylinder, but it's not reaching the caliper. A restricted brake line would block fluid flow, preventing it from exiting the bleeder screw.
Why the other options are wrong
- A. An internal master cylinder leak would cause a sinking or spongy pedal, and fluid would still typically come out if the line was open.
- B. A clogged bleeder screw is possible, but less likely if the line leading to it is clear. It also doesn't explain the firm pedal with no fluid.
- C. A seized caliper piston would prevent the pad from moving, but fluid would still flow through the caliper and out the bleeder screw if the line was open.
Restricted Brake Line
A blockage or collapse within a brake line, preventing the proper flow of hydraulic fluid to the brake component it serves.
- Can be caused by corrosion or internal damage
- Prevents fluid from reaching caliper/wheel cylinder
- Leads to lack of braking at affected wheel or difficulty bleeding
Memory trick: Firm pedal, no fluid's flow, restricted line is the pathway's woe!