Automobile & Light Truck Certification Test A5 BrakesHydraulic System Diagnosis and RepairEasy
A technician is inspecting a vehicle's brake system and notices that the brake fluid in the reservoir is dark and has a burnt smell. What is the most likely cause for this condition?
- AContamination with power steering fluid
- BOver-pressurization of the hydraulic system
- CNormal wear and tear of internal components
- DExcessive heat generation and fluid degradation
Show answer & explanationAnswer & explanation
Correct answer: D. Excessive heat generation and fluid degradation
Dark and burnt-smelling brake fluid is a strong indicator of excessive heat exposure and degradation of the fluid's properties, which reduces its effectiveness and can damage components.
Why the other options are wrong
- A. Contamination with other fluids would change the fluid's properties and color, but a burnt smell specifically points to heat degradation.
- B. Over-pressurization might cause leaks or component failure, but not typically a burnt smell or dark fluid.
- C. While some discoloration can occur with age, a dark, burnt smell is beyond normal wear and tear and indicates a problem.
Brake Fluid Degradation
Brake fluid degrades over time and with excessive heat exposure, leading to reduced boiling point, loss of lubricating properties, and potential system damage.
- Heat is the primary cause of degradation.
- Degraded fluid can appear dark or burnt-smelling.
- Reduces braking efficiency and can cause component failure.
Memory trick: Hot fluid smells burnt, looks dark, and loses its spark.