Automobile & Light Truck Certification Test A5 BrakesHydraulic System Diagnosis and RepairMedium
A technician is diagnosing a vehicle with a spongy brake pedal. After performing a thorough visual inspection, they notice that the flexible brake hose leading to the right front caliper appears swollen and bulging. When the brake pedal is depressed, the bulge becomes more pronounced. Which of the following is the MOST likely symptom this hose is causing?
- AA brake pull to the left during braking.
- BA brake pull to the right during braking.
- CA hard pedal requiring excessive force.
- DPremature rear wheel lock-up.
Show answer & explanationAnswer & explanation
Correct answer: A. A brake pull to the left during braking.
A swollen or bulging flexible brake hose indicates internal damage. When pressure is applied, the hose expands, absorbing some of the hydraulic pressure instead of transmitting it fully to the caliper. If the right front hose is compromised, the left front caliper will receive more effective pressure, causing the vehicle to pull to the left.
Why the other options are wrong
- B. A pull to the right would occur if the left front brake was weaker or the right front brake was stronger, which is the opposite of what a bulging right front hose would cause.
- C. A hard pedal is typically caused by a booster issue or a completely restricted line, not a bulging hose.
- D. Premature rear wheel lock-up is usually a sign of a faulty proportioning valve or excessive rear brake force.
Flexible Brake Hose Swelling
Internal deterioration of a flexible brake hose causing it to expand or bulge under hydraulic pressure, reducing effective pressure to the caliper.
- Caused by internal hose damage/age.
- Absorbs hydraulic pressure, weakening brake.
- Leads to uneven braking and pulling.
Memory trick: Bulging hose, pressure goes, pull it shows.