I was driving and my brakes felt different, it had some vibration. By the time I made it home the petal was on the floor. I checked it and did not have any visible leaking and the break fluid was about half. When the car is running the brake petal goes to the floor after a few pumps but not running they are normal. I'm thinking its the brake boost or master cylinder. Any thoughts?

 

When you press the brake pedal with the car running, does the idle drop?

 

The idle stays the same.

 

Any brake work done recently?

 

Last brake job was done about a year ago.

 

I just checked it this morning when I Checked the brake boost check valve and the brakes work and the check valve works. I'm puzzled. I'm thinking master cylinder is going bad and I have air in the line. But I don't want to just start replacing parts spending money.

 

You have a leak in the brake system. in order for the master cylinder to lose fluid, there has to be a leak. check all the brake lines and calipers. after you find the leak and repair the leak. bleed your brake system. should go back to normal.

 

+1 that's what I was thinking. Master cylinder makes sense too though if your booster is good.

 

If the brake pedal is nice and firm when the car isn’t running, its unlikely that the master cylinder is your problem. I think you have a fluid leak somewhere. Check all the hard & flexible lines and their connections. Brake fluid doesn’t just disappear. Also check the flexible brake lines for rot, damage or bulging when you press the brake pedal. Rotten flexible brake lines will expand when you press the brake pedal and cause the same effect as having air in the lines.

Good luck...

 

Thank you all for the help. I checked the brake boost and replaced the master cylinder. I also did a complete inspection and changed the fluid as it looked like swamp water. I drove it for about a week now ad all seems good. Thanks again for the help.