Hey guys so here's what I got going on. I just recently changed my brake pads. Shortly after this my brake booster began whining. It's not a high pitched hiss or anything so it's not an air leak. When I tap the brakes even super lightly the noise goes away then comes back 2 seconds later. I'm going to do a full flush just because my brake fluid is dirty anyways. Before I do though I was just wondering if anyone has heard of this and if air in the lines could even cause this whine. My brakes do feel squidhy so I figure there's air in the lines. I've just never heard of a brake booster doing this.

 

The booster may have a leak. It's filled with vacuum so what you hear is air getting sucked in.

 

From what I've researched Ive gotten the idea that if that was the case it would sound like more of an air leak type problem. It doesn't have any sort of hiss or anything. It's really more of a low pitched growl more than anything. I guess mostly what I'm asking is would air in the brake lines cause any sort of sound or would it just make my brakes squishy?

 

Just makes them spongy. Air in the lines will make no sounds what so ever.

 

Your booster is either leaking air past a seal, causing it to vibrate(not always a hiss, I've heard grumbling, squealing, and once, quacking...weird) Or, and this is a long shot, investigate the check valve, I've seen the diaphragm in them get hard and make strange sounds. One way to test the booster is to remove the vac line and plug it, then go drive, Remember, you will have no power brakes. Noise gone? Ok, it's definitely in the booster or check valve. Reinstall vac line without the check valve(once again, you may not have power brakes) Got noise? Booster. No noise? Valve.