I noticed after a week that my brake fluid was leaking. I'd have the brake light come on, checked fluid reservoir and it was low. It was also a bit harder to brake (more force required on the brake pedal). The first thing I did when I brought it in my garage was open the hood, put my hand under the brake booster and pulled my hand out with a lot of wetness and hard black stuff. Im thinking its leaking between the booster and the master cylinder. So that means just the brake booster is bad and replace it, right? Anything with the master cylinder that I should do?

 

The booster can only leak vacuum, it has no fluid, so it's definitely the master cylinder you need to replace.
The "hard black stuff" is probably paint from the booster, eaten off by the leak.

 

There's no brake fluid in the booster. That should clue you in on what's busted.

 

Alright well its the first time Ive ran into something like this so just making sure. But I have to press on the brake pedal harder to stop so could the leak affect the pressure applied from the booster? I dont wanna buy a new brake booster or master cylinder if just the o ring needs replacing where its leaking from. The leak is right at the cylinder where it meets the booster, right in between.

 

Have you checked the wear on your pads? If they're worn out that will also make breaking worse , especially with a failing master cylinder.

They're likely fine , but it wouldn't hurt to check.

 

If there is brake fluid between your master and booster then the master is leaking. Any seal between the master body and booster is just to keep dust/dirt out of the booster.

Brake fluid in the booster from a master leak, can be bad for the booster diaphragm and cause problems also depending on how long the master has been leaking.

 

I checked the brake pads while I was at it and theyre still good.

Im dont know exactly when it started leaking but Id say a few weeks ago more or less