The Acura Brake Master Cylinder is the force behind stopping your vehicle upon demand. The brake master cylinder takes the action from the brake pedal being pushed down and converts it to hydraulic pressure on your Acura vehicle. This pressure is then transferred to the different brake assemblies where it is used to force the pads and shoes out so friction can be created that actually stops your vehicle.
The brake master cylinder is located on the driver's side of the firewall in the engine compartment. It is mounted to the vacuum brake booster with two studs that hold it into place. When the brake pedal is pushed down, a rod forces the movement of the piston inside of the brake master cylinder that compresses the hydraulic fluid. This is how the pressure is built-up in the braking system.
On the piston are two polymer seals that hold the pressurized hydraulic fluid in the brake lines as the piston moves. It is these polymer seals that in time will rupture and cause the master cylinder not capable of pressurizing the hydraulic fluid on your Acura. The driver will realize this when the brake pedal has to travel farther and feels squishy when the brakes are being applied.
The rupture in the Acura brake master cylinder seals will not have any outward leaking of hydraulic fluid for an inspector to locate. The only indication that the brake master cylinder is failing is the lack of pressure when the brake pedal is being pushed down by the driver. If the Acura owner notices a reduction in braking potential of their vehicle but no brake fluid leaking, then the master cylinder should be suspected as the failing component.