I am curious about how long residual vacuum should persist after shutting down engine. There is no vacuum left in my pedal after about 6 hours.

Is that a precursor to leaks? What is considered normal? when should one suspect a booster problem?

 

My vacuum lasts about 4 days. Anything longer than that and the pedal is hard. My 2005 must of had vacuum leaks because it only lasted a few minutes. I am going to buy a smoke machine to test my vacuum system.