Is the brake hosted suppose to hold vacuum after engine shut down? My pedal isn't hard to push, it stays down and doesn't try to push back up after you kill engine so it all seems to be working on as far as brake booster oPeration. When I went to pull check valve out it hissed like it was pulling air back in I'm assuming, is this normal?

My issue is I have. Vibration noise around 2200-2300rpm under load, then goes away around 2400 and up, I can't for the life of me find anything loose, so started thinking maybe booster was messed up inside making this noise, kinda sounds like snoring. Is this possible with my booster appearing to be working correctly?

 

Brake boosters dont vibrate, they do go bad over time especially if brake fluid has leaked inside.


Honestly its really hard to figure out a noise or vibration over the internet.