power booster check valve

[scamp1973]

how do you check it to make sure its working properly..i don't want to replace the booster if I don't have to

 

[67Dart273]

Start the engine and let it idle. Apply the brakes once or twice so you know what you are "feeling."

Stop the engine for ?? 10 seconds, and apply the brakes ONCE and pay attention to "how they feel." They should feel just like the engine is running

Apply them again

And a third time. Sometime in the second and third stroke, the pedal should change feel, become firmer, and "no boost."

What you are "feeling" is the depletion of the reserve vacuum stored in the booster

 

[RedFish]

Try to blow through it both directions. If its good air will pass only one way.