so i was changing the brake filter thing today and i decided to see if the check valve on the brake booster worked? so i disconnected the hose and blew into it. i couldnt, it was like the valve was working and stopped the flow, so i figured i'd suck on it then (ha ha dirty minds) and still was not able to suck any air from it either, like the valve works both ways.

so how exactly does this little brake valve thing work or is mine bad?

think i answered my own question but if you dont like to read here are the cliff notes.

-the brake pedal pushes a rod that passes through the booster into the master cylinder, actuating the master-cylinder piston.

-The engine creates a partial vacuum inside the vacuum booster on both sides of the diaphragm. When you hit the brake pedal, the rod cracks open a valve, allowing air to enter the booster on one side of the diaphragm while sealing off the vacuum. This increases pressure on that side of the diaphragm so that it helps to push the rod, which in turn pushes the piston in the master cylinder.

As the brake pedal is released, the valve seals off the outside air supply while reopening the vacuum valve. This restores vacuum to both sides of the diaphragm, allowing everything to return to its original position.

 

Start the car. Turn off the car. Remove the check valve. Sucking sound=good. No sound=bad.