The brakes on a vehicle work OK for a while, then the vehicle slows because the brakes self-applied. Technician A says that an overfilled master cylinder could be the cause. Technician B says that a blocked vent port (compensating port) could be the cause. Which technician is correct?

Question

Quizplus · Accepted Answer

Both technicians are correct. An overfilled master cylinder can cause hydraulic fluid to not have enough space to expand, leading to brake application. A blocked vent port prevents pressure from equalizing, also potentially causing brakes to self-apply.

The Brakes on a Vehicle Work OK for a While