If you suspect that your brake booster is not functioning properly, it is important to test it to ensure that your vehicle is safe to drive. To test the amplifier function, start the engine with moderate pressure on the brake pedal. If the amplifier works correctly, the pedal will drop slightly. Next, disconnect the vacuum supply hose from the amplifier and attach a vacuum gauge to the hose using a cone-shaped adapter.
Check for any kinks, cracks, or other damage in the hose and make sure that there is good suction. If there are no leaks, restrain the hose to reduce vacuum loss and reinsert the one-way valve into the vacuum amplifier. Turn off the engine and immediately remove the one-way valve from the amplifier. If the amplifier maintains the vacuum, you will hear a loud whistle.
If there is no noise or very little can be heard, check that the one-way valve is working properly by attaching it to the mouth and placing suction on one side and then on the other. If air can be drawn through the valve in one direction and not the other, it is functioning correctly. If air can be sucked in on both sides, it needs to be replaced. If the valve is OK, then the amplifier is in poor condition and needs to be replaced.
Observe the mounting surfaces on which the master cylinder is mounted on the amplifier for any brake fluid leakage. If there is any present, change both the master cylinder and amplifier as it will ruin the new one. If no problem is found right now, check for any issues with front disc brakes as they can harden the brake pedal. Remove the brake caliper and clean its slides thoroughly before smearing some grease on its pins. Other possible problems include a faulty brake booster or vacuum line (check valve) or problems with the master cylinder. To confirm your diagnosis if you think that a brake booster has failed, use a portable vacuum pump.
This simple guide explains how conventional electric brake vacuum amplifiers work (found in most gasoline-powered vehicles). The brake booster was developed to be placed between the master cylinder and driver's pedal to facilitate pedal movement. Press the brake pedal hard one last time and leave your foot on it when you start the engine. If you still think that your tests don't seem conclusive or that your amplifier comes with a different configuration, consult your vehicle's repair manual for more information. To understand how power brake boosters fit into modern braking systems, it is essential to explain how brakes work. Atmospheric pressure and vacuum help push a rod against a master cylinder which uses a hydraulic system to apply brakes without much effort from you. If you feel that your brake pedal is too strong while driving and that both vacuum hose and non-return valve are working properly, you will most likely need to replace your brake booster.
Using a piece of hose can help isolate noise from either brake booster (vacuum noise on line or inside) or master cylinder (internal or external leaks).If you have tension in brakes with car on but once car starts pedal goes to ground without any tension, driving vehicle to repair center is not recommended so visit mobile mechanic instead.
